Medicinal Research Reviews 2012, 32(1), 166–215 ErbB family receptor inhibitors as therapeutic agents in breast cancer: Current status and future clinical perspective Ruchi Saxena and Anila Dwivedi* Division of Endocrinology Central Drug Research Institute, CSIR, Lucknow-26001, (U.P.), India *Corresponding author: A. Dwivedi, e-mail: [email protected]; Phone: 091- 0522- 2612411-18, Extn 4438 Fax: +91-091-(522)-2623405 / 2623938 / 2629504 ABSTRACT Breast cancer is the most common cancer diagnosed in women and the second most common cause of female cancer related deaths with more than one million new cases diagnosed per year throughout the world. With the recent advances in the knowledge of cellular processes and signaling pathways involved in the pathogenesis of breast cancer, the current focus of researchers and clinicians is to develop novel treatment strategies that can be included in the armamentarium against breast cancer. With the failure of endocrine- targeted therapy and the development of resistance to existing chemotherapy, the most explored pathway as next generation target for breast cancer therapy has been the EGFR (ErbB-1)/HER-2 (ErbB-2) pathway. The present review focuses on the rationale for targeting members of ErbB receptor family and numerous agents that are in use for inhibiting the pathway. The mechanism of action, preclinical and clinical trial data of the agents that are in use for targeting the EGFR/HER-2 pathway and the current status thereof have been discussed in detail. In addition, the future clinical promises these agents hold either as monotherapy or as combination therapy with conventional agents or with other antisignaling agents have been pondered, so as to provide better and more efficacious treatment strategies for breast cancer patients. KEYWORDS: ErbB; EGFR; HER-2; breast cancer; tyrosine kinase 1. INTRODUCTION Breast cancer is the most common female cancer and the second most common cause of female cancer related deaths with more than one million new cases diagnosed per year throughout the world.1 Despite advances in the early detection of breast cancer and the advent of novel targeted therapies, breast cancer still remains a significant public health problem due to the involvement of multiple aberrant and redundant signaling pathways in the tumorigenesis and the development of resistance to the existing therapeutic agents. Initially, various cytotoxic agents were employed for the treatment of breast cancer. These agents were non-selective and included alkylating agents, anthracyclines, anti-metabolites and tumor antibiotics that kill neoplastic cells by causing DNA damage, interference with DNA repair mechanisms and disturbance of metabolic pathways.2 Soon after combination strategy was formulated as the simultaneous 3-4 combination of two or more agents provided better results. In 1980s clinical trials in breast cancer patients gave many new agents including the taxanes – paclitaxel and docetaxel.5 Though these agents caused tumor regression but cellular toxicity caused by these agents was a serious problem. Subsequently, the endocrine therapy was introduced for early stage breast cancer as large number of tumors were found to be estrogen dependent 6. With the increasing understanding of cellular processes involved in breast cancer at molecular level and the signaling pathways involved, focus Medicinal Research Reviews 2012, 32(1), 166–215 was later, directed towards the development of targeted therapies for more efficacious treatment of breast cancer. Besides, for the formulation of correct therapy for an individual, it became essential to identify the class of the tumor based on the phenotypic markers 7 and a newer classification, was proposed: (i) Estrogen receptor (ER) - positive or luminal type: These low grade tumors are characterized by gene expression patterns similar to normal cells that line the breast ducts and glands and show positive immunohistochemical staining for luminal cytokeratins 8/18.These are further categorized into two types –(a) Luminal A type that express higher levels of estrogen receptor and have better prognosis, (b) Luminal B type that more often express EGFR or HER-2 and have poor prognosis.8,9 The arrival of estrogen antagonist tamoxifen and more recently aromatase inhibitors have significantly prolonged the survival of patients with ER positive luminal A type disease.6, 10-11 (ii) HER-2 type: These are characterized by extra copies of the HER-2 (ErbB-2) gene and are usually of high grade. These cancers grow faster and show poor patient outcome. However, targeted therapies such as trastuzumab and lapatinib are proving to be useful in the treatment of such cancers.12-13 (iii) Basal type: The gene expression pattern of such cancers is similar to those of basal cells that line the outer basal layer of mammary duct, including expression of keratin 5, keratin 6, keratin 17 and four kallikrein genes (klk5-klk8). There tumors show normal expression of HER-2 (ErbB-2) and lower expression of ER.13-14 The “triple negative subgroup” of the basal type lacks expression of estrogen receptor and progesterone receptors, have normal expression of HER-2 and are p53 mutated.15-16 These are high grade cancers, grow faster and have a lower ‘recurrence –free’ and overall survival, regardless of disease stage at diagnosis. This type of cancer is more common among women with BRCA1 mutations.17-18 These cancers do not respond to hormonal therapy and anti-HER-2 targeted therapy. The poly (ADP-ribose) polymerase (PARP) inhibitors appear to be among the most promising treatments under investigation for BRCA-associated cancers and sporadic triple-negative disease.19-22 However, recent findings report that most (>60 %) basal like tumors are EGFR-positive and EGFR-inhibitors are being evaluated in clinical trials in pre-selected patients with basal like tumors.23-24 This modern classification of breast cancer based on molecular features, has directed the efforts of scientists towards the identification and development of agents that would target specific cellular processes/ receptor type with a view to benefit a particular group of patients. In this review, the targeted therapies for breast cancer patients currently undergoing clinical trials have been discussed with special focus on ErbB family receptor inhibitors. 2. TARGETED THERAPIES FOR BREAST CANCER The first selective and targeted therapy came when it was found that majority of cases of breast cancer express higher levels of estrogen receptor-α (ERα).25-28 With the evolving understanding of the biology of ERα pathway, selective estrogen receptor modulators (SERMs) were developed that represented the first targeted endocrine therapy.29-30 Tamoxifen is currently the first line endocrine agent for the treatment of ERα-positive primary and advanced breast cancers.28,30-33 As an adjuvant therapy in early breast cancer, tamoxifen improves overall survival (OS) and its widespread use has led to a reduction of about 26% in breast cancer mortality for both pre- and post-menopausal patients.6,32-34 In previously untreated metastatic breast cancer, more than 50% of ERα- positive tumors achieve an objective response or tumor stabilization on tamoxifen treatment.35-39 Further, tamoxifen shows clinical application as a preventive agent for hormone dependent breast cancer and it also appears to maintain bone density.40-42 Despite the obvious advantages and benefits associated with the use of tamoxifen, there are some negative side-effects that include increased incidences of endometrial cancer in post menopausal women,43-44 increased occurrences of hot flashes and other menopausal symptoms,43 increased blood clots and increased cataracts.45 Another problem with the use of tamoxifen is that all patients with metastatic disease and about 40% patients on adjuvant Medicinal Research Reviews 2012, 32(1), 166–215 tamoxifen therapy eventually relapse and ultimately die from this disease and many ERα-positive patients do not respond to tamoxifen therapy at all.46-47 Several mechanisms of resistance to tamoxifen therapy have been proposed.48-52 These include: (1) decrease in or loss of expression of ERα;49 (2) increased expression of coactivator proteins like Amplified in breast and ovarian cancer-1 (AIB-1) gene amplification51 (AIB-1 associates with other coactivators and the ER transcription machinery to form large complexes capable of synergistically activating ER mediated transcription); (3) decreased expression of corepressors like Nuclear receptor Corepressor (NCoR)52 (NCoR associates with the transcription assembly and influence transcription by recruiting the histone deacetylase complex which leads to chromatin-condensation and decreased rates of transcription); (4) activated growth factor pathways that lead to phosphorylation of ER-α and ligand independent growth signals and cross-talk between ER-α and EGFR/HER-2 pathways which is discussed in detail in Section 3.2.53-55 Fig 1: Potential sites for therapeutic intervention in growth factor mediated pathway. Therapeutic agents specifically targeted at the inhibition of growth factor receptors and events within the signal transduction pathway include antireceptor antibodies, receptor tyrosine kinase inhibitor, farnesyl transferase inhibitor, bcl-2 antisense nucleotide, topoisomerase II inhibitors, and inhibitors of several other signaling intermediates like PKC inhibitor, Ras/Raf/MEK pathway and mTOR/PI3K/Akt pathway inhibitors. In many clinical cases, the lack of response to endocrine therapy together with increased metastasis was found to be associated with overexpression of EGFR/HER-2 and increased crosstalk of this pathway with ERα.56-58 Thus, targeting the growth factor - mediated signaling has become an important therapeutic option for breast cancer treatment. Modes of blocking growth factor signaling include (i) ligand antagonists, (ii) anti-receptor antibodies, (iii) small molecule tyrosine kinase inhibitors, (iv) farnesyl transferase inhibitors and (v) antisense oligonucleotides. These inhibitors can be employed at various steps to ultimately effect gene transcription via growth factor signaling (Fig.1). Therapeutic agents specifically targeted at the inhibition of growth factor receptors and several downstream targets including PKC, MAPK pathway, mTOR/PI3K/Akt pathway, inhibitors of bcl-2, topoisomerase II and ubiquitin proteasome pathway are being developed.59-65 These inhibitors have met various degrees of success and Medicinal Research Reviews 2012, 32(1), 166–215 are under different phases of clinical trials. A summary and overview of the targeted therapies for breast cancer is given in Table - I. Table-Ι: A bird’s eye view of targeted therapies for breast cancer S.No. Pathway targeted /type of therapy Agent Phase of clinical trial for breast cancer 1. Endocrine Therapy 1. Selective Estrogen Receptor Modulators (SERMs) Tamoxifen Raloxifene FDA approved FDA approved for BC risk reduction 2. Aromatase Inhibitors Anastrazole FDA approved for adjuvant therapy of ER+ve BC FDA approved for adjuvant therapy of ER+ve BC FDA approved for adjuvant therapy of ER+ve BC FDA approved for refractory ER+ve MBC Letrozole Exemestane 3. Pure antiestrogen 2. 3. 4. 5. 6. 7. ICI 182,780 Epidermal growth factor receptor 1. Monoclonal antibody Trastuzumab Pertuzumab Cetuximab Approved for HER2 overexpressing BC Phase II Phase II 2. Small molecule inhibitors Gefitinib Erlotinib Lapatinib Canertinib HKI-272 Phase II Phase II FDA approved for MBC Phase II Phase II 1. Monoclonal antibody Bevacizumab FDA approved for ER-ve BC 2. Small molecule inhibitors Pazopanib Sunitinib Axitinib Sorafenib Phase II Phase II Phase II Phase II 1. Farnesyl Transferase Inhibitor 2. Raf inhibitor Antisense oligonucleotide Small molecule inhibitor 3. MEK inhibitor Mammalian Target of Rapamycin and the PI3K/Akt pathway Topoisomerase II R115777 Phase II ISIS 5132 Bay 43-9006 CI-1040 CCI-779 RAD001 C1311 Phase II Phase I Phase II Phase II Phase II Phase II Hsp90 (ubiquitin proteasome pathway) Tanespimycin Phase II Vascular endothelial Growth factor receptor Ras/Raf/MEK/ERK pathway The following sections will briefly review the current status of ErbB receptor inhibitors particularly the EGFR/HER-2 receptor inhibitors developed / being developed so far, for breast cancer therapy and their future clinical implications will be discussed. Medicinal Research Reviews 2012, 32(1), 166–215 3. ErbB RECEPTORS AS A TARGET FOR BREAST CANCER THERAPY The epidermal growth factor receptor family i.e. ErbB family serves as an excellent candidate for therapeutic intervention based on studies of tumor formation, which is defined by aberrant cell proliferation.66-67 To date, four members of ErbB receptor family have been identified: (i) EGFR (HER1/ErbB-1), (ii) HER-2 (ErbB-2/neu), (iii) HER-3 (ErbB-3) and (iv) HER-4 (ErbB-4). These ErbB receptor family members promote tumor cell proliferation as well as survival in a variety of malignancies including breast, lung, prostate, head and neck, stomach, kidney, brain and pancreas.68-75 EGFR is overexpressed in 16-48% of the human breast cancers and an association has been reported between EGFR expression and poor prognosis.76-77 EGFR is also found to be overexpressed in ‘triple-negative’ breast cancers which are characterized by their unique molecular profile, aggressive behavior and distinct patterns of metastasis.1315 Hence EGFR could also serve as a target for therapeutic intervention in subgroup of triple negative breast cancer patients that overexpress EGFR. HER-2 is overexpressed in 25-30% of all human breast carcinomas and a significant correlation between overexpression and reduced survival of breast cancer patients has been found.73-78 Further, overexpression of these ErbB receptor family members may mediate endocrine resistance, due to crosstalk with the ER signal transduction pathways, 56-58,68 as already mentioned in the previous section . Fig 2: Structure of a typical ErbB family receptor showing (1) The extracellular domain containing cysteine rich ligand binding domains I, II, III and IV (2) Transmembrane domain and (3) The intracellular domains i.e. juxtamembrane domain; tyrosine kinase domain and regulatory region domain, including autophosphorylated tyrosine. 3.1. ErbB RECEPTOR SIGNALING ErbB family receptors are transmembrane receptor tyrosine kinases, composed of an extracellular ligandbinding domain;79-81 a trans-membrane domain that anchors the receptor to the membrane; a juxtamembrane domain which is believed to regulate various functional aspects of ErbB receptor including control of the tyrosine kinase activity (Fig. 2), receptor downregulation, ligand internalization, Medicinal Research Reviews 2012, 32(1), 166–215 and receptor sorting. The domain also has binding motifs that mediate its interaction with second messengers like calmodulin82-83; and an intracellular tyrosine kinase domain with enzymatic activity.84 The cytoplasmic domain also consists of a carboxy-terminal tail containing tyrosine autophosphorylation sites which link these receptors to proteins containing Src homology 2 (SH2) and phosphotyrosine-binding (PTB) domain motifs. In the absence of a ligand, the receptors exist as inactive monomers. When the ligands like epidermal growth factor (EGF) and transforming growth factor-α (TGF- α) bind to receptors causing some conformational changes, it results in homo- or hetero- dimerization of the receptors.85 Dimerization of receptor brings the intracellular C-terminal tyrosine kinase domains in close proximity to each other, leading to autophosphorylation. This in turn allows for docking of second messenger proteins like Src homology domain consensus protein (Shc) and growth factor receptor-bound protein (Grb-2) containing SH2 or PTB domains on these phosphorylated tyrosine residues on the receptor,86 activating multiple downstream pathways involved in tumor progression and metastatic disease. Major pathways associated with ErbB signaling include the Ras/mitogen activated protein kinase (MAPK) pathway, the phosphatidyl inositol 3-kinase (PI3K)/Akt pathway, the Janus kinase(JAK)/signal transducers and activators of transcription (STAT) pathway, and the phospholipase Cγ (PLCγ) pathway (Fig. 3). These signaling pathways ultimately affect cell proliferation, survival, motility, and adhesion.87-92 Fig 3: The ErbB signaling pathway. The ErbB family receptors are activated by binding to ligands, including EGF, TGF-heparin-binding EGF-like growth factor, amphiregulin, betacellulin, and epiregulin.Ligand binding induces formation of functionally active dimers (details given in Fig. 4). Dimerization induces the activation of the intracellular tyrosine kinase domain, which leads to autophosphorylation of the receptor on multiple tyrosine residues. This in turn leads to recruitment of adaptor proteins like Shc, Grb-2 and activates a series of intracellular signaling cascades to effect gene transcription resulting in cancer cell proliferation, invasion, metastasis and also stimulates tumor induced angiogenesis. The extracellular portion i.e. the N-terminus of ErbB receptors is the ligand binding domain and binds a variety of ligands.93 The ligands of ErbB family receptors can be divided into three groups based on their affinities for various receptors: (i) epidermal growth factor (EGF), transforming growth factor α (TGF- α), and amphiregulin bind to EGFR (HER-1 i.e. ErbB-1);94-96 (ii) betacellulin, heparin-binding growth factors, and epiregulin can interact with both EGFR (HER-1/ ErbB-1) and HER-4 (ErbB-4);97-100 and (iii) tomoregulins and heregulins/neuregulins (NRG-1, NRG-2, NRG-3, NRG-4) bind to HER-4 (ErbB-4). NRG-1 and NRG-2 also bind to HER-3 (ErbB-4).101-102 There is no known ligand for HER-2 Medicinal Research Reviews 2012, 32(1), 166–215 (ErbB-2), but it is the preferred hetero-dimerization partner for other members of the ErbB receptor family (Fig. 4).93 A List of ErbB family receptors and their cognate ligands is given in Table - II. Fig 4: ErbB family receptor dimerization and downstream signaling. Ligand binding to the receptor induces formation of homo- or hetero-dimers. Upon dimerization the intracellular tyrosine kinase domains of the receptors get phosphorylated and thus get activated. The active dimers subsequently initiate downstream signaling. (details given in Fig. 3). 1, EGFR (HER-1); 2,- HER-2; 3, HER-3; 4, HER-4. Table-ІІ: ErbB family receptors and their ligands Receptor Ligands EGFR (ErbB-1/HER-1) Epidermal growth factor (EGF) Transforming growth factor-α (TGFα) Epiregulin (EP) Amphiregulin (AR) Betacellulin (BTC) Heparin-binding EGF-like growth factor (HB-EGF) HER-2 (ErbB-2) Unknown HER-3 (ErbB-3) Neuregulin(NRG-1)/heregulin(HRG) isoforms NRG-2α and β HER-4 (ErbB-4) NRG-1/HRG isoforms NRG-2α and β NRG-3 NRG-4 Tomoregulin HB-EGF BTC EP The ErbB receptor family regulates cell proliferation, differentiation, apoptosis, invasion, and angiogenesis and thus plays an important role in normal organogenesis by mediating morphogenesis and Medicinal Research Reviews 2012, 32(1), 166–215 differentiation in normal conditions.103-105 In normal cells, the EGFR/HER-2 signaling pathway is under tight regulation by different regulatory mechanisms but this tight control is often lost in case of tumor cells due to which they gain the advantage to proliferate under adverse conditions, metastasize to surrounding tissues, and increase angiogenesis.66-67 Under normal conditions, when a ligand binds to ErbB family receptor, the receptor gets activated which triggers the downstream signaling but in tumor cells, ligand independent activation of the receptor can occur.85-90 Several mechanisms have been proposed for this ligand -independent activation : (i) Overexpression of the wild type EGFR/HER-2 in some cases like cancers of breast, lung, glioblastoma, head and neck cancer, bladder carcinoma, ovarian carcinoma, and prostate cancer, may lead to ligand independent receptor dimerization and subsequent up regulation of EGFR/HER-2 signalling.95,106-107 (ii) Gene amplification is not a commonly reported phenomenon in tumors, with the exception of glioblastoma108 and 20-25% of ER-positive breast cancers that overexpess HER-2.78 (iii) Presence of mutant EGFR causing it to be inappropriately activated. These mutations include point mutations or deletions in the tyrosine kinase activation domain,109-110 seen in about 81% non-small cell lung cancer (NSCLC), and deletion in the extracellular domain (EGFRviii variant), seen in about 2% NSCLC,109-111 25-50% cases of glioblastomas112-113 and in 42% of head and neck cancers.110 However, there are no known tyrosine kinase domain mutations in breast cancer. (iv) Dysregulation of the EGFR pathway in some cancers could be a result of overexpression of TGF-α, an EGFR ligand, leading to the development of an autocrine loop.114 3.2. ROLE OF EGFR/HER-2 IN ENDOCRINE RESISTANCE : CROSS TALK MECHANISM The ER-induced signaling mechanism coupled with the fact that over two thirds of breast cancers exhibit high expression of ER, have provided the rationale for preventing and treating breast cancer by estrogen antagonism, highlighted by the discovery of tamoxifen. However, a serious problem emerging with the use of tamoxifen is intrinsic or acquired resistance to endocrine agents.46-47 Cumulative clinical data suggest that patients with HER-2 and EGFR overexpressing tumors have a poorer outcome when treated with tamoxifen.115-117 Many patients present with primary (de novo) resistance to endocrine therapy, despite high tumor levels of ER, and all patients with advanced disease eventually acquire resistance.48-50 Although as mentioned in earlier Section 2, a number of probable explanations for the development of resistance to endocrine therapy have been given, the activation of ER and the cross-talk between ER-α and EGFR/HER-2 pathways appears to be one of the major players. For example, the membrane bound ERs play key role in the mechanism of cross-talk between ERs and growth factor receptors.118-120 In addition to the activation of gene transcription via the genomic pathway, ER regulates its nongenomic functions via the membrane estrogen receptor mediated signaling.121-123 The membrane estrogen receptors functionally mimic the growth factor ligands and increase the levels of second messengers such as cyclic-adenosine monophosphate (c-AMP) within minutes124-126 which in turn activate various tyrosine kinase receptors such as Insulin-like growth factor-1 receptor (IGF-1R) , EGFR, and HER-2.127-128 ER can also interact with the growth factor receptors either by associating with adaptor molecules or by direct phosphorylation of EGFR/HER-2. Finally, ER-induced signaling pathway also induce EGFR ligands such as TGF-and cause downregulation of EGFR and HER-2.129-131 The crosstalk between the ER and the growth factor signaling pathway is bidirectional. The ER can be phosphorylated at serine-118 within its activation function-1 (AF-1) domain by the MAPKs (Erk1/2) and Akt which are downstream components of EGFR/HER-2 pathway, leading to ligandindependent ER activation.132-133Also, serine-167 in AF-1 is phosphorylated by the ribosomal S6 kinase (RSK) which is itself activated by Erk1 and Erk2.134-136 In addition, phosphorylation of ER coregulatory 137-138 proteins by growth factor kinases modulate the ER signaling pathway. For example, phosphorylation of ER coactivator AIB1 by MAPK increases ER-dependent transcription,139-140 and overexpression of AIB1 converts tamoxifen-bound ER into an estrogen agonist rather than an Medicinal Research Reviews 2012, 32(1), 166–215 antagonist.124 These finding suggests that the crosstalk between the ER and EGFR/HER-2 signaling pathways has an important role in tamoxifen resistance. Delineation of the interplay between the estrogens, ER, and ER cross-talk with receptors like EGFR and HER-2 should be an important diagnostic and prognostic objective in anti-EGFR/ HER-2 therapy. 4. EGFR/HER-2 INHIBITORS IN BREAST CANCER THERAPY Overexpression of at least two of the members (EGFR and HER-2) of the ErbB receptor family has been associated with a more aggressive clinical behavior. Thus, ErbB receptor family was identified early as an important target for drug development. Till date, a number of therapeutic strategies have been developed which specifically target either intracellular or extracellular domains of the EGFR and its family members.74-76,129-130 The extracellular portion of the receptor can be targeted either by the use of ligand antagonists or by monoclonal antibodies against the receptor. Attempts to make small molecules that could compete with EGFR/HER-2 ligands for the ligand binding domain of the receptor have not met success and this strategy is discontinued.141 Monoclonal antibodies bind to the extracellular domain of the receptor preventing its activation by the ligand. A summary of monoclonal antibodies is given in TableIII. The intracellular portion of the receptor can be targeted by using the small molecule tyrosine kinase inhibitors that block the adenosine triphosphate (ATP) binding site of the tyrosine kinase domain as summarized in Table- IV. Table-ΙΙI: Summary of the anti-EGFR/HER-2 monoclonal antibodies for breast cancer treatment Agent Class of EGFR/HER-2 inhibitor Phase of clinical developm -ent FDA approved Adverse effects Clinical activity in Source breast cancer Refer ences Trastuzumab Anti HER-2 antibody Cardiac dysfunction, cardiotoxicity As monotherapy in HER2 overexpressing breast cancer, c/w TKIs and Tam Roche 155160 Pertuzumab Anti HER-2 antibody Phase II Diarrhea, pain, c/w Trastuzumab nausea, Vomiting, mucositis Roche 216221 Cetuximab Anti-EGFR antibody Phase II Rash, diarrhea, c/w carboplatin nausea, triple negative BC vomiting c/w Ironotecan 234237 Agent Gefitinib Erlotinib Lapatinib Canertinib Neratinib S.No. 1. 2. 3. 4. 5. Structure Irreversible pan-HER inhibitor Irreversible pan-HER inhibitor Irreversible Dual TKI for EGFR/ HER2 Reversible EGFR inhibitor Reversible EGFR inhibitor Class of EGFR inhibitor Phase I/II Phase II FDA approved for MBC Phase II Phase II Phase of clinical trial c/w trastuzumab; c/w paclitaxel monotherpy monotherapy in inflammatory BC; c/w trastuzumab; c/w bevacizumab c/w pertuzumab c/w anastrazole Clinical activity in breast cancer Pfizer Glaxo Smith Kline Genentech /Roche Astra Zeneca Source Covalently binds to a conserved cysteine residue located in the kinase domains of these proteins. covalently binds to the ATP binding site of the intracellular kinase domain inhibitor of the intracellular tyrosine kinase domains of both EGFR andHER2 receptors inhibits EGFR tyrosine kinase by binding to the ATPbinding site of the enzyme. inhibits EGFR tyrosine kinase by binding to the ATPbinding site of the enzyme. Mechanism of action Diarrhea, nausea Rash, nausea, vomiting, asthenia, diarrhea, mucosutis, hypersensitivity, thrombocytopenia Rash, diarrhea, nausea, vomiting Rash, diarrhea, nausea, fatigue, headache Rash, diarrhea, nausea, vomiting Adverse effects 302306 296297 269270, 288 264267 246247 Refer ences Medicinal Research Reviews 2012, 32(1), 166–215 Medicinal Research Reviews 2012, 32(1), 166–215 4.1. ANTI-EGFR/HER-2 MONOCLONAL ANTIBODIES 4.1.1. TRASTUZUMAB HER-2 overexpression is seen in 15-30% of breast cancers and is usually caused by gene amplification.142143 It is linked to higher grade and extensive forms of ductal carcinoma in situ144-145 and is also associated with adverse outcome in invasive lobular carcinoma.78,146 In order to select the patients that are likely to benefit from HER-2 targeted therapy, it is important to determine the status of HER-2 in breast cancer. Currently, two types of tests i.e. immunohistochemistry (IHC) that detects receptor overexpression and fluorescence in situ hybridization (FISH) that identifies HER-2 gene amplification, are used for the purpose.147-149 Though detection of HER-2 by FISH is more accurate but it requires special equipments that makes it more expensive. Recent reports indicate a considerable degree of concordance between the two methods of detection on same tumor specimens. While 100% concordance was observed in IHC 3+ readings when compared with FISH, cases with 2+ IHC score were not very reproducible.150 Thus, such patients must have a confirmatory FISH test before administration of trastuzumab therapy. When compared to IHC, FISH test is also found to be a better predictor of response to trastuzumab therapy and overall prognosis. Another test known as chromogenic in situ hybridization (CISH) uses small DNA probes to count the number of HER-2 genes in breast cancer cells.151-152 This has advantage over FISH of being less expensive as it measures color changes and doesn’t require a special microscope. Newer tests are being developed that could measure the amount of HER-2 protein in cancer cells more precisely and thus help in identification of patients who could respond to HER-2 targeted therapies such as trastuzumab. Trastuzumab is a humanized anti-HER-2 monoclonal antibody that has been approved for treatment of patients with breast cancers that overexpress HER-2 protein or that exhibit HER-2 gene amplification.153 It binds to the extracellular domain IV of HER-2, important in facilitating the overall conformational change induced by binding of the ligand to the receptor.154-155 In this way, trastuzumab exhibits its antitumor activity either by antibody-dependent cell mediated cytotoxicity, downregulation of signaling following antibody mediated receptor internalization, or inhibition of signaling through other 156-57 members of the ErbB receptor family by preventing the formation of heterodimer. This in turn will result in decreased angiogenesis, increased apoptosis and decreased proliferation. This antibody therapy was initially targeted specifically for patients with advanced relapsed breast cancer that overexpressed the HER-2 protein.158-159 Since its launch in 1998, trastuzumab has become an important therapeutic option for patients with HER-2/neu-positive breast cancer. It is widely used for its approved indication as a second line of treatment for advanced metastatic disease, and is also being studied in adjuvant treatment for earlier-stage disease and in neoadjuvant treatment protocols.160-163 220.127.116.11. TRASTUZUMAB AS FIRST/ SECOND LINE MONOTHERAPY IN MBC The efficacy and safety of trastuzumab as monotherapy has been assessed in various phase II trials. In one such trial, 164 trastuzumab was administered weekly to 46 patients with pretreated metastatic breast cancer whose tumors overexpressed HER-2. A loading dose of 250 mg trastuzumab was administered intravenously, followed by 10 weekly doses of 100 mg each. After 10 weeks, patients with no disease progression were given weekly maintenance dose of 100 mg. Toxicity was minimal, with no antibodies formed against trastuzumab. Objective responses were observed in 5 of the 43 evaluable patients, including 1 complete response (CR) and 4 partial responses (PR), for an overall response rate (ORR) of 11.6%. Responses were seen in mediastinum, lymph nodes, liver, and chest wall lesions. Minor responses (seen in 2 patients) and stable disease (14 patients) lasted for a median of 5.1 months. These results demonstrated that trastuzumab is well tolerated and Medicinal Research Reviews 2012, 32(1), 166–215 clinically active in patients with HER-2 overexpressing metastatic breast cancers (MBC) with extensive prior therapy. The efficacy of trastuzumab as a single agent was also assessed in a pivotal phase II study by Cobleigh et al. (1999), 165 on heavily pretreated patients whose tumor overexpressed HER-2 at the 2+ and 3+ levels by IHC. The ORR in this group was 15% with a median survival (MS) of 9.1 months in this population refractory to anthracyclines and taxoids treatment. Retrospective analysis of response rate (RR) and median survival (MS) restricted to the patients whose tumors overexpressed HER-2 at the highest levels (IHC 3+) showed a RR of 18% and MS of 16.4 months. Another Phase II study166 investigated the clinical efficacy and safety of trastuzumab monotherapy as first-line treatment given once every 3 weeks in woman with HER-2 positive MBC. In 105 patients receiving five cycles of therapy, the ORR was 19% and the clinical benefit rate (CBR) was 33%. Median time-to-progression (TTP) was 3.4 months. The monotherapy was well tolerated and no significant adverse events were reported. The most common treatment-related adverse events were only mild-tomoderate rigors, pyrexia, headaches, nausea, and fatigue. In a recently published study, 167 where trastuzumab was used as a single agent, the RR in 111 assessable patients with 3+ IHC staining was 35% and the RR for 2+ cases was 0%; the response rates in patients with and without HER-2 gene amplification detected by FISH were 34 and 7%, respectively. 103 It is now clear that 3+ expression by IHC method or gene amplification demonstrated by FISH is required for likely benefit from trastuzumab. The most common adverse effects of trastuzumab were mild to moderate infusion-related reactions, which are usually noted with the first infusion and decrease in frequency thereafter. The most clinically significant adverse event included symptomatic cardiac dysfunction, which occurred in 2% to 4.7% of patients on trastuzumab monotherapy. Thus trastuzumab was accepted to be effective and tolerable in first or second line treatment of HER-2 positive metastatic breast cancer as single agent. 18.104.22.168. TRASTUZUMAB IN COMBINATION THERAPY Many landmark phase II and phase III trials reported additive and synergistic activity of trastuzumab when used in combination with standard chemotherapy (either paclitaxel or anthracycline based). In the pivotal randomized phase III study by Slamon et al. 2001,168 patients were randomized to receive chemotherapy with or without trastuzumab. Patients were grouped according to whether or not adjuvant chemotherapy contained an anthracycline, such that the majority of patients who did not have adjuvant chemotherapy or adjuvant therapy not containing an anthracycline were randomized to doxorubicin and cyclophosphamide with or without trastuzumab. In the group, with adjuvant anthracycline, patients were randomized to paclitaxel with or without trastuzumab. TTP was significantly longer in each of the combination subgroups (cyclophosphamide vs. trastuzumab + cyclophosphamide, 6.1 months vs. 7.8 months; paclitaxel vs. trastuzumab + paclitaxel, 2.7 months vs.6.9 months). When both chemotherapy subsets were considered, a survival benefit attributable to trastuzumab with chemotherapy vs. chemotherapy alone was noted (MS, 25 months vs. 20 months). This observed survival difference was despite the fact that nearly three-quarters of patients treated initially with chemotherapy alone crossed over to trastuzumab as a single agent on progression of disease. The retrospective analysis showed that the difference was much greater in all the parameters in case of patients with HER-2 expression level of 3+ as determined by IHC. These two studies by Cobleigh et al.165 and Slamon et al.168 led to the licensing of trastuzumab as treatment for metastatic breast cancer. In the pivotal phase III trastuzumab combination trial, 169 trastuzumab was associated with class III or IV cardiac dysfunction in 27% of the anthracycline and cyclophosphamide plus trastuzumab-treated group compared with 8% of the group given an anthracycline and cyclophosphamide alone. Cardiac toxicity has remained a significant limiting factor for the use of trastuzumab since its FDA approval in late 1998. Trastuzumab trials since then have included cardiac eligibility criteria and prospective cardiac Medicinal Research Reviews 2012, 32(1), 166–215 monitoring. The incidence of congestive heart failure in a pooled analysis of six recent trials was 2.7%. Cardiotoxicity is usually reversible and manageable even with continued trastuzumab therapy. A randomized, multicenter trial, 170 compared first-line trastuzumab plus docetaxel vs. docetaxel alone in patients with HER-2 positive MBC. Trastuzumab plus docetaxel was significantly superior to docetaxel alone in terms of ORR (61% vs. 34%), Overall survival (OS) (median, 31.2 v 22.7 months; P < .0325), TTP (median, 11.7 vs. 6.1 months), time to treatment failure (median, 9.8 vs. 5.3 months), and duration of response (median, 11.7 v 5.7 months). There was little difference in the number and severity of adverse events between the arms. Another randomized Phase II study,171 evaluated the activity of weekly paclitaxel vs. its combination with trastuzumab for treatment of patients with advanced breast cancer overexpressing HER2. The combination group exhibited superior ORR (75% vs. 56.9%), particularly in the subset of IHC 3+ patients (84.5% vs. 47.5%). A statistically significant better median TTP was also seen in the subgroup with IHC 3+ (369 vs. 272 days) and visceral disease (301 vs. 183 days). Thus weekly paclitaxel plus trastuzumab was found to be highly active and safe and it is superior to paclitaxel alone in patients with IHC score of 3+. The combination of trastuzumab and navelbine has been tested in the phase II setting. 172 The ORR to the combination in patients with metastatic disease was 75%, and in patients whose tumors overexpressed HER-2 at the IHC 3+ level, it was 80%. The combination was well tolerated. Trastuzumab was also tested in combination with vinorelbine, 173 because vinorelbine therapy is not associated with cardiotoxicity, alopecia, or significant gastrointestinal side effects. In a phase II trial, 174 trastuzumab was administered weekly with vinorelbine on the same day. The ORR was 68%. Median time to treatment failure was 5.6 months; 38% of patients were progression free after one year. The data support the use of trastuzumab and vinorelbine as a safe, well-tolerated, and effective first-line treatment for women with HER-2 positive MBC. In a similar trial by Papaldo et al. (2006),175 that compared vinorelbine alone with vinorelbine plus weekly trastuzumab as combination therapy, the combination group showed higher ORR (51.4% vs.27.3%). The median duration of response was 8 months for women treated with vinorelbine and 10 months for those who received the combination. Patients in the combination arm also had a longer TTP (9 months vs. 6 months) and OS (27 months vs. 22 months) Toxicity was mild in both groups. Concerning cardiotoxicity in combination group, 20% patients had left ventricular systolic dysfunction. A study by De Maio et al. (2007), 176 tested the activity of the same combination, with trastuzumab given every 3 weeks. Activity of 3-weekly trastuzumab plus vinorelbine fell within the range of results reported with weekly schedules. Toxicity was prevalently manageable. This combination was found to be safe and active for metastatic breast cancer patients who received adjuvant taxanes with anthracyclines. Trastuzumab was also tested in combination with polychemotherpy. Burris et al. (2004),177 tested efficacy and toxicity of weekly paclitaxel/carboplatin with or without trastuzumab following initial treatment with trastuzumab. Patients were given trastuzumab (8 mg/kg followed by 4 mg/kg/wk) for 8 weeks. Out of 61 patients in the trial, 52 patients were assessable for response and all 61 patients were assessable for survival. Out of the 52 patients, 33% experienced a PR to trastuzumab monotherapy and given 8 additional weeks of trastuzumab, 29% had stable disease and proceeded to receive paclitaxel/carboplatin/trastuzumab. 31 patients with measurable disease were assessable for response after initial single-agent trastuzumab followed by paclitaxel/carboplatin/trastuzumab. An ORR of 84%, median TTP of 14.2 months, and median OS of 32.2 months was reported with the triplet combination. In the patients treated with paclitaxel/carboplatin alone after disease progression on initial trastuzumab, an ORR of 69%, median TTP of 8.3 months, and median OS of 22.2 months was reported. Median TTP for all 61 patients is 10 months and the median OS is 26.7 months. This trial confirmed the activity and tolerability of weekly paclitaxel/carboplatin alone or in combination with trastuzumab in women with HER-2 overexpressing MBC. Robert et al. (2006), 178 conducted a phase III multicenter trial to evaluate the safety and efficacy of trastuzumab and paclitaxel with or without carboplatin in HER-2 overexpresing MBC. Patients were randomized to recieve six cycles of either trastuzumab 4 mg/kg loading dose plus 2 mg/kg weekly thereafter with paclitaxel 175 mg/m2 every 3 weeks , or trastuzumab 4 mg/kg loading dose plus 2 Medicinal Research Reviews 2012, 32(1), 166–215 mg/kg weekly thereafter with paclitaxel 175 mg/m2 and carboplatin area under the time-concentration curve = 6 every 3 weeks followed by weekly trastuzumab alone. The ORR was 52% for the triplet combination versus 36% for combination of trastuzumab and paclitaxel, median progression free survival (PFS) was 10.7 months and 7.1 months respectively. The improved clinical response with triple combination was more evident in HER-2 3+ patients. Both regimens were well tolerated, and febrile neutropenia and neurotoxicity occurred infrequently; Grade 4 neutropenia occurred more frequently with triple combination. 22.214.171.124. TRASTUZUMAB AFTER DISEASE PROGRESSION Trastuzumab has clearly revolutionized treatment for HER-2 positive patients; however in majority of the cases disease progression occurs within 1 year of treatment. It is also uncertain whether further trastuzumab either as monotherapy or in combination with chemotherapy is of any benefit. It is also unknown if retreatment on relapse is useful for patients on adjuvant trastuzumab. Preclinical studies by Fujimoto-Ouchi et al. (2005)179 suggested that trastuzumab in combination with chemotherapy can slow down tumor growth in the presence of disease progression on trastuzumab monotherapy. Clinical evidences for the use of trasuzumab after disease progression are largely derived from the retrospective studies.180-183 The retrospective analyses suggest that continuation of trastuzumab beyond disease progression in patients with HER-2 overexpressing metastatic breast cancer appears to be of value, producing responses and clinical benefit, and is well tolerated without significant cardiac toxicity. The feasibility of this approach warranted examination in prospective trials. However a similar analysis by Montemurru et al.184 gave contrasting results. A phase II trial by Bartsch et al. 185 evaluated the efficacy and safety of gemcitabine and trastuzumab after earlier exposure to anthracyclines, docetaxel and/or vinorelbine, and trastuzumab. Patients received gemcitabine at a dose of 1,250 mg/m² on day one and eight, every 21 days. Trastuzumab was administered in three-week cycles. Earlier therapies consisted of trastuzumab (100%), anthracyclines (100%), vinorelbine (96.6%), docetaxel (72.4%), and capecitabine (72.4%). Nineteen point two percent patients experienced PR, and stable disease ≥ 6 months was observed in a further 26.9%, resulting in a clinical benefit rate of 46.2%. TTP was median 3 months, and OS 17 months. Neutropenia (20.7%), thrombocytopenia (13.8%), and nausea (3.4%) were the only treatment-related adverse effects that occurred with grade 3 or 4 intensity. Four patients (13.8%) developed brain metstasis (BM) while on therapy. Together with the favourable toxicity profile, this regimen appeared to be a safe and potentially effective salvage therapy option in a heavily pre-treated population. A phase III trial By O’Shaughnessy et al. 186 comparing trastuzumab and lapatinib with lapatinib alone did not give significant evidence in favor of using trastuzumab after disease progression. Another phase III randomized trial, 187 GBG26/TBP, investigated the efficacy of continuing trastuzumab plus capecitabine compared to capecitabine alone in patients progressing on any prior trastuzumab treatment. The study required 482 patients, with the first interim analysis to be done after 150 events. However, it was closed early on after recruiting 156 patients. The final analysis reported statistically significant advantage for the combination arm with increase in RR (48% vs. 27%) and mean TPP (8.2 vs. 5.6 months) with no significant increase in OS. In a recent trial, the effect of Ttrastuzumab on survival after BM was analyzed in 78 HER-2 positive breast cancer patients.188 Patients were grouped according to trastuzumab therapy; no treatment and treatment before and after BM were diagnosed. The OS after the diagnosis of BM as well as TTP of intracranial tumors was prolonged in patients who received trastuzumab after BM was diagnosed. Conversely, BM occurred much later in patients who received trastuzumab before BM. In the multivariate Cox regression model, age at BM <50 years, disease-free interval of about 24 months, TTP of intracranial tumor of about 4.8 months, and trastuzumab treatment after BM were signiﬁcantly associated with longer survival after the onset of BM. Thus trastuzumab therapy after the onset of BM in HER-2 positive breast Early-stage invasive BC, node positive or high-risk node negative Early-stage invasive BC, node positive or high-risk node negative Early stage, node positive, invasive BC Node positive or high risk node negative Early stage, node positive or node negative BC NCCTG N9831 NSABP B-31 BCIRG 006 FINHER Tumor characteristics HERA Study 232 3222 3969 3401 Patient no. 3 A: doxorubicin+cyclophosphamide→ docetaxel B: doxorubicin+cyclophosphamide→docetaxel+ trastuzumab A: docetaxel or vinorelbine→cyclophosphamide+ fluorouracil+epirubicin B: docetaxel or vinorelbine +trastuzumab→ cyclophosphamide +fluorouracil+epirubicin 3 3 A: doxorubicin+cyclophosphamide→paclitaxel B: doxorubicin+cyclophosphamide →paclitaxel+ trastuzumab C: docetaxel+carbopltin+trastuzumab 3 2 Median follow up A: doxorubicin+cyclophosphamide→paclitaxel B: doxorubicin+cyclophosphamide →paclitaxel+ trastuzumab C: doxorubicin+cyclophosphamide →paclitaxel →trastuzumab A: chemotherpy→observation B: chemotherapy→trastuzumab for 1 yr C: chemotherapy→trastuzumab for 2 yrs Arms Table V: Summary of the randomized phase III trials of Trastuzumab in adjuvant therapy 88% at 3 yrs 95% at 3 yrs 0.41(0.16-1.08) 89% at 3 yrs 0.42(0.21-0.83) 90% at 4 yrs 0.66(0.47-0.93) 86% at 4 yrs 92% at 4 yrs 0.59(0.40-0.85) 89% at yrs 93% at 4 yrs 0.63(0.49-0.81) 92% at 3 yrs 90% at 3 yrs 0.66 (0.47-0.91) OS HR(95%CI) 78% at 3 yrs 82% at 4 yrs 0.67(0.54-0.83) 77% at 4 yrs 83% at 4 yrs 0.61(0.37-0.65) 73% at 4 yrs 86% at 4 yrs 0.49(0.41-0.58) 4 % at 3 yrs 83% at 3 yrs 0.64(0.54-0.76) DFS HR(95%CI) Medicinal Research Reviews 2012, 32(1), 166–215 Medicinal Research Reviews 2012, 32(1), 166–215 cancer patients is associated with a signiﬁcant survival beneﬁt after BM diagnosis compared with patients who never received or completed trastuzumab before the BM diagnosis. Thus, trastuzumab appears be useful in preventing BM, but there are no definitive evidences to support the continuation of trastuzumab after disease progression. Also, because trastuzumab does not appear to cross the blood brain barrier efficiently, it seems to be of limited use in preventing metastasis. 126.96.36.199. TRASTUZUMAB IN ADJUVANT SETTING Some large international randomized clinical trial have been conducted to test the efficacy of trastuzumab in the adjuvant settings and have given encouraging outcomes except for the PACS04 trial.189, 277 Characteristics of the included trials for trastuzumab are summarized in Table-V. HER-2 positivity was assessed by IHC and FISH in the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-31, North Central Cancer Treatment Group (NCCTG) 9831, and Herceptin Adjuvant (HERA) trials, by IHC and CISH in the Finland Herceptin2 (FinHer) trial, and by FISH only in the Breast Cancer International Group (BCIRG) 006 trial. Patients at high risk for recurrence were enrolled in all studies, as demonstrated by the high prevalence of hormone receptor negative disease and node-positive disease in the populations accrued. Three trials (the NASBP B-31, NCCTG N9831, and BCIRG 006 trials) evaluated the combination of doxorubicin and cyclophosphamide followed by an anthracycline, with or without trastuzumab. The HERA, BCIRG 006, and NCCTG N9831 trials were three-arm studies, while the FinHer trial was a 2 x 2 study (randomizing all patients to vinorelbine or docetaxel and then randomizing the HER-2 positive subgroup to trastuzumab or observation).190-191 Similar sudy design of the (NSABP) B-31 and (NCCTG) 9831 led to the joint analysis of these trials192. Both these trials included treatment with the standard adjuvant chemotherapy regimen of doxorubicin plus cyclophosphamide followed by paclitaxel and 1 year with or without concurrent trastuzumab therapy in women with operable HER-2 positive breast cancer. The combined analysis of data from these two treatment arms was approved by the National Cancer Institute (NCI). A third arm included in the N9831 study, in which patients received sequential trastuzumab after administration of doxorubicin plus cyclophosphamide and paclitaxel, was not included in the combined analysis, but the interim analysis by Perez et al. (2006),193 compared this sequential arm with the control and concurrent trastuzumab–paclitaxel arms. The absolute difference in disease-free survival (DFS) between the trastuzumab group and the control group was 12% at three years. Trastuzumab therapy was associated with a 33% reduction in the risk of death. The three-year cumulative incidence of class III or IV congestive heart failure or death from cardiac causes in the trastuzumab group was 4.1% in trial B-31 and 2.9% in trial N9831. Both the studies suggest that trastuzumab combined with paclitaxel after doxorubicin and cyclophosphamide improves outcomes among women with surgically removed HER-2 positive breast cancer. The HERA trial,190,194 was a multicenter, randomized, three-arm trial in patients with HER-2 positive early stage invasive BC who have completed at least four cycles of (neo)adjuvant chemotherapy, with or without radiotherapy. Patients were randomized to observation only, 1 year of trastuzumab, or 2 years of trastuzumab, given on a 3-weekly schedule. Efficacy results for the standard approach and the 1year trastuzumab therapy treatment arms have been reported. At a 1-year median follow-up, patients treated with trastuzumab in the HERA trial experienced a 46% lower risk of a first event than patients under observation. This corresponded to an absolute benefit of 8.4% in DFS favoring trastuzumab at 2 years. Overall survival in the two groups was not significantly different (29 deaths with trastuzumab vs. 37 with observation). Severe cardiotoxicity developed in 0.5% of the women who were treated with trastuzumab. The HERA trial thus concluded that one year of treatment with trastuzumab after adjuvant chemotherapy significantly improves DFS among women with HER-2 positive breast cancer. The Breast Cancer International Research Group (BCIRG) 006 trial, 195 was designed to assess the role of trastuzumab in a docetaxel-containing chemotherapy regimen with or without doxorubicin. Patients were randomized to one of three regimens: doxorubicin plus cyclophosphamide followed by docetaxel, doxorubicin plus cyclophosphamide followed by docetaxel with concurrent trastuzumab, or combined Medicinal Research Reviews 2012, 32(1), 166–215 docetaxel, carboplatin, and trastuzumab that did not contain an anthracycline. In an interim analysis presented at the 2006 San Antonio Breast Cancer Symposium (SABCS), investigators confirmed that, at a median follow-up of 3 years, the addition of trastuzumab to chemotherapy resulted in a significantly longer survival time than with standard adjuvant chemotherapy alone for patients with HER-2 positive breast cancer. A 39% longer DFS duration for patients in the doxorubicin plus cyclophosphamide followed by docetaxel with concurrent trastuzumab arm and a 41% longer OS time were found compared with the doxorubicin plus cyclophosphamide followed by docetaxel control arm. Similarly, a 33% longer DFS time for combined docetaxel, carboplatin, and trastuzumab and a 34% longer OS time were found, compared with the the doxorubicin plus cyclophosphamide followed by docetaxel control arm. The difference in DFS between the two investigational arms was not considered to be statistically significant. The FinHer trial, 196 compared docetaxel with vinorelbine for the adjuvant treatment of early breast cancer. The patients were randomized to three cycles of docetaxel or vinorelbine followed by three cycles of fluorouracil, epirubicin, and cyclophosphamide. The patients of HER-2 positive subgroup were further randomized to either receive or not receive trastuzumab for 9 weeks along with the first three cycles of docetaxel or vinorelbine. DFS at three years with docetaxel was 91% vs. 86% with vinorelbine but OS did not differ between the groups. Within the subgroup of patients who had HER-2 positive cancer, those who received trastuzumab had a DFS of 89 % vs. 78 % for the subgroup without trastuzumab. The trial led to the conclusion that docetaxel was associated with more adverse events than vinorelbine. Trastuzumab was not associated with decreased left ventricular ejection fraction or cardiac failure. Adjuvant treatment with docetaxel, as compared with vinorelbine, improves DFS in women with early breast cancer. A short course of trastuzumab administered concomitantly with docetaxel or vinorelbine is effective in women with breast cancer who have an amplified HER-2 gene. Though trastuzumab seems to be promising in the adjuvant settings, the question that remains unanswered is the treatment duration and regimen and if it should be given simultaneously or sequentially after chemotherapy. Comparison of trials B-31 and N9831 and the HERA trial suggests that cardiotoxicity is lower after sequential administration. However, we cannot rule out the possibility that simultaneous administration of chemotherapy and trastuzumab is more effective than sequential administration. Simutaneous administration gives cytotoxic effects while sequential administration is cytostatic. Another problem associated with the combination of chemotherapy with adjuvant trastuzumab is cardiotoxicity which limits the benefits of the therapy. Further follow-up of the adjuvant trials will add to the knowledge of the nature and reversibility of cardiac events associated with trastuzumab use and will help in formulating an optimal combination for an individual patient. Presently, trastuzumab appears to be the best treatment available for HER-2 positive breast cancer patients, but there are some issues associated with its use. Firstly, selection of patients who could benefit from trastuzumab therapy should be more accurate. The cardiotoxicity associated with trastuzumab is another serious problem which could be combated with the formulation of optimum treatment strategy in relation to dose, duration and combination with other agents. The emerging problem with trastuzumab therapy is development of resistance to the agent. The majority of HER-2 overexpressing tumors demonstrated primary (de novo or intrinsic) resistance to single-agent trastuzumab. In fact, the rate of primary resistance to single-agent trastuzumab for HER-2 overexpressing MBC is 66% to 88%.165-168 The majority of patients who achieve an initial response to trastuzumab in combination with chemotherapy develop resistance within one year.169-171 In the adjuvant setting, administration of trastuzumab in combination with or following chemotherapy improves the DFS and OS rates in patients with early stage breast cancer.192-195 However, approximately 15% of these women still develop metastatic disease despite trastuzumab-based adjuvant chemotherapy. 188.8.131.52. MECHANISM OF DEVELOPMENT OF TRASTUZUMAB RESISTANCE The majority of HER-2 overexpressing breast cancers either develops resistance or do not respond to trastuzumab therapy alone. This could be due to the one of the following reasons: Medicinal Research Reviews 2012, 32(1), 166–215 (1) Overexpression of MUC4 sterically hinders trastuzumab from binding HER-2 surface receptor and may mediate cross-talk to activate HER-2 leading to disrupted interaction between HER-2 and trastuzumab.197-198 (2) Expression of redundant survival signaling pathways like the insulin-like growth factor (IGF) receptor; growth factor ligands of EGFR, HER-3, or HER-4 (EGF, betacellulin, heregulin) reduce growth inhibitory effect of trastuzumab by 57, 84, and 90 percent, respectively.199-200,202 (3) Deficient expression of the PTEN tumor suppressor gene and enhanced PI3K signaling.203 (4) Expression of p95 truncated form of HER-2 that lacks the extracellular domain, which is the recognition site for trastuzumab.204 In HER-2 overexpressing cancer cells, the extracellular domain (ECD) of HER-2 is cleaved by the sheddases like ADAM (a disintegrin and metalloproteinase) family of zincdependent, membrane-associated metalloprotease.204-205 The ectodomain shed of HER-2 renders its remaining transmembrane portion, p95, a constitutively active, phosphorylated tyrosine kinase. 206-208 In vitro studies indicate that the p95 fragment of HER-2 is 10–100 times more oncogenic than the full length receptor.195 In the clinic, the presence of the ECD in the serum of cancer patients has been linked to a poor prognosis,208-211 with decreases in serum ECD levels during treatment being a predictor of response to trastuzumab therapy.212-214 Accordingly, inhibition of the sheddases responsible for ECD shedding and p95 production may have potential therapeutic benefit in HER-2 positive patients. (5) Downregulation of the cyclin-dependent kinase inhibitor p27kip1.215-217 However, these mechanisms of trastuzumab resistance do not appear to preclude the antitumor activity of small molecule inhibitors of ErbB family receptors. 4.1.2. PERTUZUMAB / 2C4 Pertuzumab is a recombinant humanized monoclonal antibody (2C4) that binds to the extracellular domain II of the HER-2 receptor.218-219 Through its binding, it blocks the ability of dimerization between HER-2 receptor with other ErbB family receptors. Pertuzumab is referred to as a HER dimerization inhibitor, or HDI. Pertuzumab binds at different positions on the receptor from trastuzumab, blocking the pathway through different mechanisms and inhibiting cellular proliferation.201,220 Phase I clinical trial221-222 with pertuzumab as monotherapy has given promising results. Initial phase II studies223 of pertuzumab in MBC patients showed that pertuzumab was safe and well tolerated but had limited efficacy in this group of patients. Phase I and II trials have both demonstrated synergy between pertuzumab and trastuzumab, with the addition of pertuzumab to trastuzumab providing responses among women refractory to trastuzumab therapy. The first Phase II study224 evaluating pertuzumab plus trastuzumab included 66 patients with HER-2 positive, metastatic breast cancer who had progressed on trastuzumab therapy. Overall responses were achieved in 24% of patients with 7.6% CR and 16.7% partial response PR. Disease stabilization for at least six months was achieved in nearly 26% of patients. The adverse effects of this combination included diarrhea, pain, nausea, vomiting and mucositis. There is a hope that the combination of trastuzumab and pertuzumab used with chemotherapy will be even more effective if used to treat women newly diagnosed with advanced cancer. The combination is being evaluated in first-line MBC patients in another study; CLEOPATRA (CLinical Evaluation Of Pertuzumab and TRAstuzumab) conducted by Roche.225 This phase III study began recruiting patients in January 2008 and is underway in 18 countries worldwide. If this study is successful, this combination of trastuzumab plus pertuzumab and chemotherapy has the potential to become a new standard of care in HER-2 positive MBC patients. 4.1.3. CETUXIMAB / C225 Cetuximab is a human-mouse chimeric monoclonal antibody derived from the murine anti-EGFR monoclonal antibody M225.226-227 It has shown growth inhibitory effects in EGFR overexpressing cell lines and tumor xenografts 226,228 and so was considered for the treatment of EGFR overexpressing breast cancer patients including the triple negative cases that overexpress EGFR.15,22-23 It competitively binds to the accessible extracellular domain III of EGFR with high affinity preventing EGFR ligand binding and Medicinal Research Reviews 2012, 32(1), 166–215 inhibiting receptor dimerization.229-230 Irreversible binding of EGFR by Cetuximab facilitates receptor internalization and subsequent degradation. Receptor downmodulation induces cell-cycle arrest, upregulation of p27Kip1 and subsequently inhibits tumor growth and metastasis.228, 231 Cetuximab may also work by mediating complement fixation and ADCC (antibody dependent- cell mediated cytotoxicity). More importantly, this antibody is able to block the activation of the tyrosine kinase domain of the EGFR following stimulation with a specific ligand.232-233 In addition, blockade of the EGFR with monoclonal antibodies results in a significant inhibition of neoangiogenesis. This phenomenon seems to be related to the reduction in the synthesis of angiogenic factors such as interleukin-8 (IL-8), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in tumor cells following treatment with anti-EGFR monoclonal antibodies.234-235 Although cell lines treated with cetuximab show only a 20–40% antitumor response in vitro, tumors in athymic mice are growth inhibited by more than 75% on cetuximab treatment. Improved antitumor responses in vivo could be due to downmodulation of angiogenic factors.236-237 A supra-additive antitumor effect was observed in preclinical studies when cetuximab was combined with paclitaxel in breast cancer models. However, this combination was not found to be promising in a phase I trial due to disappointing preliminary efficacy.238 A phase II study on 163 MBC patients was done to evaluate the combination of cetuximab with irinotecan and carboplatin, the standard chemotherapeutic agents used for breast cancer therapy.239 The patients were randomized to receive either irinotecan (90 mg/m2) followed by carboplatin on days 1 and 8 of each 21-day cycle or the same treatment except with cetuximab at a dose of 400 mg/m2 i.v. for dose 1 then 250 mg/m2 weekly thereafter. The ORR was significantly improved with the addition of cetuximab than with irinotecan and carboplatin alone (39% vs. 19%) but it is associated with greater toxicity. In another phase II multi-center randomized clinical trial240 on 102 patients with metastatic triple negative (basal like) breast cancer, patients were randomly given either carboplatin in combination with weekly 2 cetuximab (250 mg/m ) or carboplatin alone. In the carboplatin monotherapy cohort 6% achieved a PR, 4% achieved stable disease, and the CBR was 10%. In the combination arm, the ORR was 18%, 9% of patients had stable disease and the CBR was 27%. Although, due to the progressive nature of the disease, most patients progressed rapidly, the combination of carboplatin and cetuximab show significantly improved anti-tumor activity in comparison to carboplatin alone. In another phase II trial cetuximab was combined with Irinotecan in patients with MBC pre-treated with an anthracycline or a taxane-based therapy but the results were not very promising in pretreated patients.241 In this study, 19 patients were treated with cetuximab 250 mg/m2 weekly and Irinotecan 80 mg/m2, the ORR was 11% with one patient achieving a PR and 1 patient achieving a CR. One patient had stable disease for 11 cycles. The combination was well tolerated with dermatologic toxicities in some cases. Thus cetuximab seems to a promising agent and requires further clinical trials to be used for the treatment of breast cancer. As it targets specifically EGFR, it also holds promise for the subgroup of patients with aggressive triple negative phenotype that overexpress EGFR. But for this patient selection is an important criterion. The majority of the studies with anti- EGFR agents merely required EGFR to be present in the tumor or have not preselected at all for patient selection. Currently, there are no accurate diagnostic methods of determining the level of EGFR expression of a tumor and hence, the clinical benefits from anti EGFR therapies are limited. More work is required to be done for the precise indication of EGFR status and predictive value of currently used preclinical models should a lso be reassessed so as to improve the clinical outcome of EGFR targeting agents. 4.2. SMALL MOLECULE TYROSINE KINASE INHIBITORS Numerous ErbB family receptor inhibitors are in clinical development but only lapatinib has received US Food and Drug Administration (FDA) approval for the treatment of breast cancer for MBC.280 These small molecules compete with ATP for binding to the kinase domain of the receptor.242 Tyrosine kinase inhibitors have several potential advantages over monoclonal antibodies. First, they are orally bioavailable Medicinal Research Reviews 2012, 32(1), 166–215 and generally well tolerated. Second, they appear active against truncated forms of HER2 receptors (p95) in vitro.243-244 Third, their small size may allow them to penetrate sanctuary sites, such as the central nervous system. Finally, by taking advantage of the homology between kinase domains of ErbB family receptors, tyrosine kinase inhibitors can be developed to target more than one member of the receptor family simultaneously.112 4.2.1. GEFITINIB Gefitinib a synthetic anilinoquinazoline is an oral, selective and reversible inhibitor of EGFR tyrosine kinase. It competes with ATP for EGFR ATP binding site within the tyrosine kinase domain of the receptor that ultimately blocks signal transduction pathway implicated in proliferation and survival of cancer cells.245 In vitro, gefitinib can bind to the related ErbB receptor family member , however, its affinity for HER-2 is 200-fold lower than that for EGFR.246 The efficacy of treatment with gefitinib improves with increasing levels of EGFR in the tumor.247 HER-2 overexpressing tumors are also susceptible to gefitinib treatment, theoretically by virtue of their heterodimerization with EGFR.248-250 While at low doses gefitinib is cytostatic in vitro, at higher doses it inhibits cellular proliferation, induces apoptosis and decreases in vitro colony formation. Several studies have demonstrated that gefitinib treatment results in a dose and time-dependent growth inhibition in solid tumors.249-251 Gefitinib treatment downmodulates levels of angiogenic factors including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) secreted by tumors in vivo, thereby lowering the degree of neoangiogenesis and microvessel production.252-253 In order to improve the antitumor efficacy of gefitinib it has been combined with chemotherapy or radiotherapy. Gefitinib administered with chemotherapeutic agents is reported to demonstrate supra additive tumor inhibition compared to either treatment alone. 253-254 Its use as monotherapy in advanced and refractory MBC has proven to be disappointing. A phase II multicenter trial was done to evaluate the antitumor activity and pharmacodynamic/biologic effect of geﬁtinib 500 mg/day monotherapy in patients with pre-treated, advanced breast cancer.255 The study showed clinically significant activity of gefitinib when used as monotherapy. However, a phase II trial by Von Minckwitz et al. (2005) evaluating gefitinib as monotherpy on patients with taxane and anthracycline 256 pretreated metastatic breast cancer did not gave encouraging results. Gefitinb monotherapy was found to be well tolerated and the side-eﬀect proﬁle was as expected from current knowledge of the drug. There was no correlation between EGFR expression and response in this study. However, its activity in combination therapy has shown more potential. Gefitinib has also been evaluated in combination therapy in two phase II studies for which it was combined with docetaxel as first line therapy. In one of these studies,257 41 patients were given oral gefitinib 250 mg per day along with docetaxel ( 75 mg/m2 or 100 mg/m2). The ORR was 54% with a CR and PR in 22 out of 41 patients. Toxicities included neutropenia, diarrhea, rash and anemia. The second study was a phase II multi-institutional trial258 to determine the efficacy and tolerability of gefitinib and docetaxel as first-line treatment in 33 patients with MBC.115 Patients received gefitinib 250 mg once daily and docetaxel 75 mg/m2 every 3 weeks, until tumor progression, toxicity or other reasons for discontinuation. The clinical benefit rate was 51.5% and the overall objective response rate was 39.4%. . The median duration of clinical benefit was 10.9 months. The most common reason for study discontinuation was disease progression (16 patients), followed by toxicity (10 patients). Toxicities were mainly attributable to docetaxel, including ≥ grade 3 neutropenia in 43% of patients rather than gefitinib. It was concluded that the combination of docetaxel and gefitinib was an active regimen in MBC, and the toxicities and efficacy were similar to those of docetaxel alone. Unfortunately, gefitinib's activity in MBC could not be elucidated in these two phase II studies as the trials did not include a docetaxel alone group for comparison. Gefitinib was also tested in combination with hormonal therapy that included anastrazole, an aromatase inhibitor approved for adjuvant therapy in the treatment of ER-positive breast cancer.259-260 In a double-blind, placebo-controlled randomized trial261 of 56 postmenopausal patients with ER-positive and EGFR-positive primary breast cancer, patients were randomly assigned to geﬁtinib (250 mg given orally Medicinal Research Reviews 2012, 32(1), 166–215 once a day) and the aromatase inhibitor, anastrazole (1 mg given orally once a day), and to geﬁtinib (250 mg given orally once a day) and placebo of identical appearance to anastrazole given orally once a day, all given for 4–6 weeks before surgery. The combination arm showed a significantly greater reduction of proliferation. Tumor size reduction of ≥30% was achieved in 14 out of 28 patients with the combination treatment and in 12 of 22 patients receiving gefitinib alone.Gefitinib was also evaluated in combination with anastrazole in a phase II multicenter, double blind, randomized trial to investigate its efficacy on reversing resistance to hormonal therapy in women with newly diagnosed hormone receptor positive MBC.262 The patients were randomized to receive anastrazole in combination with either gefitinib or placebo. The gefitinib group showed a superior PFS (14.5 months vs. 8.2 months) and CBR (49% vs. 34%) when compared with placebo. The treatment was well tolerated but adverse events were seen twice as often in the gefitinib arm when compared with the placebo arm. The results suggested that the combination of anastrazole plus gefitinib is well tolerated and shows increased anti-tumor activity when compared to anastrazole alone in MBC patients and further studies are required to evaluate its efficacy. 4.2.2. ERLOTINIB/ OSI-774 Erlotinib selectively, potently and reversibly inhibits EGFR tyrosine kinase activity of wild-type EGFR and also of the constitutively active mutant EGFRvIII.241, 263 Studies in human cancer cells found that it inhibits epidermal growth factor-dependent cell proliferation at nanomolar concentrations. It binds in a reversible fashion to the ATP binding site of the receptor, blocking the downstream pathway that leads to cellular proliferation. 132 Like gefitinib, erlotinib does not decrease the level of EGFR protein.264 Erlotinib shows activity against multiple breast cancer cell lines in vitro and in xenograft models.265 In a phase II dose escalation study of erlotinib in combination with the standard dose of trastuzumab, evidences of antineoplastic activity were observed with the recommended dose of 150 mg/day.265 In a phase II clinical trial erlotinib was given in combination with bevacizumab (a monoclonal antibody that inhibits VEGF pathway) to 13 pre-treated breast cancer patients, the response to therapy was observed in 1 out of 9 evaluable patients.266 The most commonly reported adverse events with erlotinib treatment are grade 1 or 2 rash, diarrhea, asthenia, nausea and vomiting. Erlotinib was also tried in combination with weekly docetaxel treatment as first line therapy; a RR of 55% was obtained in this trial.267 Both gefitinib and erlotinib did not show success in the treatment of breast cancer. One probable reason seems be the lack of tyrosine kinase domain mutations in cases of breast cancer. Another reason for the failure of these agents as breast cancer therapy could be inaccurate selection of patients. So there is need to develop techniques to assess the level of EGFR in tumors before the formulation of therapy for a patient. 4.2.3. LAPATINIB Lapatinib (lapatinib ditosylate), is an orally active dual inhibitor of the tyrosine kinase domain of both EGFR and HER-2. It binds to the ATP binding pocket of the tyrosine kinase domain of the receptor preventing autophosphorylation and thus inhibiting the growth signals.268 Lapatinib has shown activity in a number of diﬀerent metastatic and advanced tumor cell lines including breast cancer cell lines overexpressing either EGFR or HER-2,269-270 and has recently shown positive results in clinical testing as well. Lapatinib also binds with p95 (the truncated form of HER-2) and thus might be effective in trastuzumab resistant cases.271 This novel investigational agent has given enthusiastic results in patients with metastatic, treatment-refractory disease. It is the most clinically advanced of kinase inhibitors in breast cancer and has been approved in March 2007 for use in combination with capecitabine in patients with advanced, refractory MBC.285 Medicinal Research Reviews 2012, 32(1), 166–215 184.108.40.206. LAPATINIB AS MONOTHERAPY The efficacy of lapatinib as single agent second-line therapy in advanced/metastatic breast cancer has been studied in a number of trials. Initial suggestions of the clinical activity of lapatinib came from several phase I trials testing its safety, tolerability and pharmacokinetics. A phase I trial273 on 39 enrolled patients with solid tumors was conducted with dose-escalation from 175 to 1800 mg/day. Adverse events reported include grade 3 diarrhea (2 of 6 patients administered 900 mg lapatinib twice a day) and grade 1–2 skin rash, diarrhea, vomiting, constipation, fatigue and anorexia. Evidences of antitumor activity were observed in patients treated with 1200 mg/day of lapatinib. In another phase Ib dose ranging study by Dees et al (2004),274 in which 30 heavily pretreated breast cancer patients received lapatinib as monotherapy, 4 patients showed confirmed PR and 10 others had prolonged stable disease. All 10 had EGFR expression by IHC, and 8 of these 10 overexpressed HER-2.274 An open-label multicenter phase II study275 was done on 80 HER-2 positive MBC patients refractory to trastuzumab therapy, with an oral dose of 1500 mg daily of lapatinib. The ORR was 8%, 14% of patients achieved stable disease and 22% of patients achieved PFS. Adverse events with lapatinib were tolerable with anorexia, nausea, rash, vomiting, diarrhea, and weight loss being the most common. Cardiotoxicity was not significantly observed. Another phase II study by Gomez et al. (2005),276 assessed the efficacy of lapatinib as first line therapy in HER-2 positive MBC. The patients were randomized to receive either 1500 mg daily or 500 mg daily of lapatinib. The ORR achieved was about 24% with no significant difference between the two groups. These two phase II studies led the way for lapatinib to be investigated in further clinical trials. A phase II study (EGF20008) by Burstein et al. (2008),272 examined the safety and efficacy of lapatinib monotherapy in chemotherapy-refractory tumors. This study included 2 cohorts of patients, cohort A with HER-2 positive and cohort B with HER-2 negative patients. More than 95% of patients had stage IV disease, and nearly all patients had received 3 or more lines of anti-cancer therapy previously. 97% of HER-2 positive patients had received at least 12 weeks of prior trastuzumab therapy. Lapatinib 1500 mg daily was administered, with dose reduction to 1250 mg in the event of grade 3/4 toxicity. HER2 positive cohort showed an ORR of 1.4% versus 0.0% in the HER-2 negative cohort. The independent review reported that 5.7% of HER-2 positive patients received a clinical benefit, but there was no clinical benefit in the HER-2 negative group. Median OS was 29.4 weeks (cohort A) vs. 18.6 weeks (cohort B). These responses were modest, but this was a heavily pretreated cohort. Patients with HER-2 overexpressing breast cancer have been found to have a significantly higher risk of developing BM. Lapatinib is capable of penetrating the blood brain barrier and have been used in clinical trials for the treatment of BM. A phase II study (EGF20009)278 assessed the clinical activity and safety of lapatinib as a first line treatment in locally advanced or metastatic HER-2 positive breast cancer without prior targeted therapy. The ORR was 24% and did not differ significantly between the two dosage groups (1500 mg daily or 500 mg twice daily). The median duration of response was 28.4 weeks, and PFS was 63% at 4 months, and 43% at 6 months. This trial suggested a role for first-line lapatinib therapy in locally advanced or metastatic HER-2 positive breast cancer. Another phase II study (EGF105084) was done by Lin et al. 279 on 39 HER-2 positive patients with progressive BM. The primary end point was objective response in the CNS by Response Evaluation Criteria in Solid Tumors (RECIST). Secondary end points included objective response in non-CNS sites, time to progression, overall survival, and toxicity. One patient achieved a PR in the brain by RECIST (ORR 2.6%). 7 patients (18%) were progression free in both CNS and non-CNS sites at 16 weeks. Exploratory analyses identified additional patients with some degree of volumetric reduction in brain tumor burden. The most common AEs were grade 3 diarrheas and fatigue. Medicinal Research Reviews 2012, 32(1), 166–215 Table VI: Summary of phase II trials of lapatinib as monotherapy Study (reference) Blackwell et al. 275 Johnston et al. 280 Burstein et al. 272 Gomez et al. 276 Lin et al. 279 Kaufman et al. 281 Tumor characteristics Patient no. Lapatinib dose Response rate HER-2+, T- refractory MBC 80 1500 mg od 8% Relapsed/refractory IBC;HER-2+(n=24), EGFR+/HER2-(n=12) 36 1500 mg od 62%(PR) HER2+ 8.3%(PR) EGFR-/ HER2+ Chemo-refractory ABC/MBC 229 1500 mg od 1.4% HER2+ 0.0% HER2- First-line HER-2+ LABC/MBC 138 Arm A:1500 mg od Arm B: 500 mg bid 24% 750 mg bid 2.6% 1500 mg bid 40%-HER2+ 1PR-EGFR+/ HER-2- ve T-refractory/relapsed HER-2+ with BM Chemo-/T-refractory/ relapsed IBC, HER-2+(n=126), EGFR+/HER2-(n=15) 39 141 Lapatinib monotherapy was evaluated in patients with HER-2 positive relapsed/refractory inflammatory breast cancer. In a phase II trial (EGF103009) by Spector et al. (2006), 280 of the 24 patients with HER-2 positive tumors, 62% achieved a PR, with additional 21% experiencing stabilization of the disease. In contrast, in EGFR positive/ HER-2 negative subgroup only 8.3% of the 12 patients achieved a PR. In another study, HER-2 positive patients with inflammatory breast cancer refractory to anthracyclines, taxanes, and trastuzumab were treated with continuous lapatinib monotherapy at 1500 mg daily.281 Preliminary data demonstrated an estimated ORR of 40%. The most frequent toxicities were diarrhea and skin rash. It was concluded that lapatinib monotherapy is active in the treatment of relapsed/refractory HER-2 positive inflammatory breast cancer where currently only a few effective therapies are available. 1 A summary of phase II trials of lapatinib monotherapy is given in Table-VI. 220.127.116.11. LAPATINIB IN COMBINATION WITH OTHER TARGETED THERAPIES Lapatinib is also giving promising results in combination with other targeted agents like inhibitors of the VEGFR signaling pathway that is involved in angigiogenesis and is believed to play an important role in metastsis of breast cancer. Lapatinib in combination with pazopanib, an investigational tyrosine kinase inhibitor and angiogenesis inhibitor,282 is in phase II trial (VEG20007) in patients who have not been treated for their progressive disease. Preliminary reports show a 44% versus 30% RR for the combination arm, with a 73% versus 43% reduction in target lesions at 12 weeks.283 Another phase II trial investigated the effects of combining lapatinib with the angiogenesis inhibitor bevacizumab.284 Bevacizumab is a monoclonal antibody that specifically inhibits VEGFR mediated signaling and has been approved by FDA for the treatment of ER-negative breast cancer.285-286 The combination therapy gave promising results in heavily pretreated patients conferring a 34.4% clinical benefit at Week 24 (CR/PR/ stable disease), while 62.5% of patients had PFS at Week 12 and the combination was well tolerated. A phase III trial (EGF104900) was conducted to assess the advantage of combining lapatinib with trastuzumab in heavily pretreated HER-2 positive MBC patients refractory to trastuzumab therapy.287 In the study, 296 patients heavily pretreated with trastuzumab, were randomized to either lapatinib 1000 mg Medicinal Research Reviews 2012, 32(1), 166–215 daily plus trastuzumab 2 mg/kg weekly or lapatinib 1500 mg daily alone. The combination group demonstrated signiﬁcantly improved PFS (3 months vs. 2.1 months), and CBR (25.2% vs. 13.2%). However the differences in OS and ORR were not statistically significant. Both treatments were well tolerated with similar side-effect profile and an asymptomatic decline in left ventricular ejection fraction occurring in 5% of the patients in the combination arm and in 2% of the patients in the lapatinib only arm. The data showed that combined targeting gave better clinical outcomes in comparison with lapatinib alone in the pretreated metastatic setting. Ongoing trials involving lapatinib and trastuzumab include a phase III trial comparing paclitaxel and trastuzumab with lapatinib or placebo in HER-2 positive metastatic breast cancer (EGF104383), and a phase I study combining lapatinib, trastuzumab, carboplatin and paclitaxel (EGF103892). 18.104.22.168. LAPATINIB IN COMBINATION WITH CHEMOTHERAPY Lapatinib has also been successfully combined with chemotherapy in breast cancer patients.The standard chemotherapeutic agents with which lapatinib was tested include capecitabine and taxanes and the combination groups exhibited better prognosis in comparison to chemotherapy alone. A randomized phase III trial (EGF100151) was conducted to compare lapatinib plus capecitabine with capecitabine alone in women with advanced, progressive HER-2 positive breast cancer who experienced disease progression after treatment with regimens that included an anthracycline, a taxane, and trastuzumab.288-289 The patients were randomly allocated to receive either combination of lapatinib 1250 mg daily plus capecitabine 2000 mg daily or capecitabine 2500 mg daily alone. The interim analysis showed that the addition of lapatinib to capecitabine was associated with a 51% reduction in the risk of disease progression. The median TTP was 8.4 months in the combination group as compared with 4.4 months in the capecitabine monotherapy group. The ORR was 22% vs. 14% in favor of combination group. This improvement was achieved without an increase in serious grade 3/4 events. Again, cardiotoxicity was not a significant event. This trial led to its first approval for use in MBC patients. Lapatinib was further tested in combination therapy when it was evaluated in conjunction with taxanes. A phase III randomized double-blind study (EGF3001),290 was carried out on 579 MBC patients which were either HER-2 negative or have never been tested, The patients were randomized to receive either lapatinib 1500 mg daily combined with paclitaxel 175 mg/m2 or with paclitaxel 175 mg/m2 alone as first-line treatment. The ORR was 35% vs. 25% in favor of the combination group. However, TTP and OS were not significantly different between the two arms except in a subgroup of patients with HER-2 positive advanced breast cancer. As expected, there was a significantly greater toxicity profile in the combination group over the paclitaxel monotherapy group with alopecia, nausea, vomiting, rash and diarrhea being the most common adverse events. 22.214.171.124. LAPATINIB IN COMBINATION WITH HORMONAL THERAPY The evidences of molecular crosstalk between ER- and EGFR/HER-2 pathway, and its association with the development of resistance to hormonal therapy provides the rationale for combining treatments targeting both the pathways. Lapatinib has been tested in preclinical and clinical studies in combination with anti-estrogens like letrozole (an aromatase inhibitor) and tamoxifen (a selective estrogen receptor modulator) that are already approved for the treatment of breast cancer. Preclinical studies by Xia et al. (2006),291 provided evidence that the combining lapatinib with antiestrogen might delay or prevent the development of resistance to lapatinib in HER-2 overexpressing, ER-positive cells. There is also evidence that lapatinib can overcome hormone resistance, caused by cross-talk between HER-2 and ER, in preclinical models.292 A phase III study by Chowdhary et al. (2007),293 to compare lapatinib in combination with letrozole versus letrozole alone in post-menopausal women with ER positive MBC is currently ongoing. Patients are randomized to letrozole with or without lapatinib regardless of HER-2 status to test if lapatinib treatment prevents the conversion of ER positive/ HER-2 negative to ER positive/ Medicinal Research Reviews 2012, 32(1), 166–215 HER-2 positive breast cancer, thus blocking the development of resistance to endocrine therapy. Two phase II trials in hormone resistant, ER positive MBC are currently examining lapatinib as single agent (NCT00225758) or in combination with tamoxifen (NCT00118157). 20 5.3 25 22.8 6.7 35 A: paclitaxel +laptinib B: paclitaxel +placebo 579 HER2-ve or untested MBC Di Leo et al. 2007 response not reached 8.4 4.4 22 14 A: Capecitabine B: Capecitabine +lapatinib Chemo-/Trastuzumab -refractory HER2+ MBC Geyer et al. 2006 324 12.9 9.7 3(PFS) 2.1(PFS) 10.3 6.9 A: lapatinib B: lapatinib +trastuzumab 296 T-refractory, HER2+ MBC O’Shoughnessy et al. 2008 TTP (months) RR (%) Arms Patient no. Tumor characteristics Study (reference) Table VII: Summary of the phase III trials of Lapatinib in combination therapy OS (months) Major phase III clinical trials of lapatinib have been summarized in table -VII. Based on the available data, lapatinib was found to be an active and well-tolerated oral dual tyrosine kinase inhibitor for the treatment of HER-2 overexpressing breast cancer. Lapatinib is also active in trastuzumab refractory MBC patients. Due to its small size it can efficiently cross blood brain barrier and hence has potential benefits in patients with BM. Lapatinib is also found to be useful in inflammatory Medicinal Research Reviews 2012, 32(1), 166–215 breast cancer patients. Lapatinib is associated with either a very low incidence of or no cardiotoxicity and also does not increase toxicity when combined with trastuzumab. Recently, lapatinib treatment in a neo-adjuvant setting has shown to decrease the number of breast cancer stem cells and in tumor biopsies as opposed to chemotherapy which led to an increase.294-295 Therefore, the agents like lapatinib which are less toxic and more efficacious could be of significant importance in the treatment of breast cancer. Hence, lapatinib holds the potential to become the mainstay of HER-2 positive breast cancer therapy in future. 4.2.4. CANERTINIB / CI-1033 Canertinib/CI-1033 is an irreversible pan-erbB inhibitor. It covalently binds to the ATP binding site of the intracellular kinase domain of the receptor thus blocking the downstream signaling pathway.1, 296-297 Canertinib is a non-selective inhibitor of the members of ErbB receptor family, and thus it has a broader range of antitumor activity. As it is irreversible it has prolonged clinical effect and needs less frequent dosing. It inhibits EGFR kinase activity at low nanomolar range and has antitumor activity in EGFR and HER-2 dependent preclinical models.299 It is also active against HER-3 and HER-4 but has no effect on other tyrosine kinases. Canertinib has been shown to be active in both in vitro and in vivo tumor xenograft models of breast cancer.296 In a phase I trials of 10 heavily pretreated patients, one patient achieved stable disease for more than 25 weeks, but objective responses have not yet been reported.299-301 The adverse events associated with canertinib include grade 1–2 diarrhea, rash, nausea, and vomiting.201 At higher doses hypersensitivity reactions have also been observed. In addition to the typical EGFR-related toxicity, there is a 28% incidence of thrombocytopenia associated with canertinib, which might complicate its combination with myelosuppressive cytotoxic agents. It is presently being evaluated in phase II clinical trials. Canertinib could be a potential therapeutic agent in breast cancer patients as it is a non-specific inhibitor of ErbB receptor family but does not inhibit other receptor tyrosine kinases. Hence it has broader range of action and needs further clinical evaluation before it can be used as a therapy for breast cancer. 4.2.5. NERATINIB/HKI-272 HKI-272 is an irreversible orally active pan-HER receptor tyrosine kinase inhibitor with potential antineoplastic activity. It is a dual EGFR and HER-2 inhibitor that is in phase II clinical trial for breast cancer.1 It forms a covalent bond with the conserved cysteine residue of the ATP-binding pocket within the kinase domain of the receptor which thus prevents autophosphorylation of the receptor. HKI-272 treatment of cells results in inhibition of downstream signal transduction events and cell cycle regulatory pathways that ultimately decreases tumor cell proliferation. 302-303 It is highly active against HER-2 overexpressing human breast cancer cell lines, inhibits the EGFR kinase and proliferation of EGFRdependent cells in culture and also in xenograft models. HKI-272 also inhibits the growth of cultured cells that contain sensitizing and resistance-associated EGFR mutations.304 HKI-272 has the particular advantage of having inhibitory activity in tumors that have mutated and become resistant to reversible inhibitors like erlotinib and gefitinib.285 In a preliminary phase I trial on 51 patients, 23 with advanced stage breast cancer, resulted in two confirmed and two unconfirmed PR in breast cancer.305 The encouraging response rate in this phase I trial, led to the initiation of a phase II clinical trial of HKI-272 in patients with advanced stage breast cancer. A phase II study was carried out involving 49 advanced HER-2 positive breast cancer patients who were divided into two treatment arms. The first arm included HER-2 positive breast cancer patients pre-treated with trastuzumab and the second arm included HER-2 patients with no prior trastuzumab treatment. Tumor response and PFS data continues to be gathered, but out of 32 evaluable patients, 6 patients achieved a confirmed PR with additional patients achieving an unconfirmed PR. Diarrhea and nausea were the major adverse effects noted in the study. In another Phase II open label study306 on 102 patients with stage IIIB, IIIC, or IV breast cancer, daily oral doses of 240 mg HKI-272 were generally well tolerated Medicinal Research Reviews 2012, 32(1), 166–215 with diarrhea as the predominant adverse event.1 The primary end point was the rate of PFS defined at 16 weeks. Patients not pretreated with trastuzumab had a PFS rate of 75% while patients with prior trastuzumab treatment had a 16-week PFS of 51%. These data show HKI-272 to be useful in HER-2 positive advanced breast cancer. It is also being evaluated in combination therapy with paclitaxel and with vinorelbine in patients with advanced breast cancer.1 These clinical investigations appear promising and may lead to further treatment options for patients with advanced HER-2 positive breast cancers and also for patients refractory to agents like erlotinib and gefitinib. 5. SUMMARY AND FUTURE IMPLICATIONS In recent years, there has been significant advancement in the treatment of breast cancer, and the number of mortalities due to the disease has substantially reduced for the past few years. These accomplishments have been led by the emergence of targeted therapies that include hormonal inhibitors, growth factor receptor tyrosine kinase inhibitors,59 the farnesyl transferase inhibitors,60 the bcl-2 antisense oligonucleotides61-62 and several other signaling intermediates like mTOR/PI3K/Akt pathway inhibitors63 and inhibitors of ubiquitin proteasome pathway.64-65 Many of these agents are now integrated in the first line therapy for several groups of MBC patients and continue to be the basis of successful treatment. With increasing incidence of tumor resistance to chemotherapy in breast cancer, it is of crucial importance to apply novel therapeutic agents alongwith current treatment standards and to explore newer agents that are under investigation in clinic. The epidermal growth factor receptor family i.e. ErbB family serves as an excellent example for therapeutic intervention based on studies of tumor formation, which is defined by aberrant cell proliferation. The ErbB receptor family consists of four members viz. EGFR, HER-2, HER-3 and HER-4 and promotes tumor cell proliferation in a variety of malignancies including breast cancer Two members of the family EGFR and HER-2 are frequently overexpressed in breast cancer. EGFR is overexpressed in 16-48% of the human breast cancers and an association has been reported between EGFR expression and poor prognosis. HER-2 is over expressed in 25-30% of all human breast carcinomas and a significant correlation between overexpression and reduced survival of breast cancer patients has been found. Trastuzumab has revolutionized the HER-2 overexpressing breast cancer treatment by improving survival in metastatic breast cancers when endocrine therapy failed. However, the majority of HER-2 overexpressing breast cancers do not respond to trastuzumab therapy alone. Several reasons have been proposed for this resistance including expression of redundant survival signaling pathways like IGFR, deficient expression of tumor suppressor gene PTEN, expression of p95HER2, a truncated form of HER-2 lacking extracellular domain recognized by trastuzumab; and downregulation of cyclin dependent kinase inhibitor p27kip. Cetuximab is another monoclonal antibody that is being evaluated in clinical trials and giving promising results. Since it targets EGFR, it also holds promise for subgroup of breast cancer patients with triple negative phenotype that overexpress EGFR. Small molecule tyrosine kinase inhibitors (TKIs) have shown promise in cases that are resistant to trastuzumab therapy as these compounds compete with ATP for binding to the EGFR/HER-2 catalytic kinase domain of the receptor to block the signaling pathway. These agents are also associated with lower risk of cardio-toxicity. Though research in this field has been going on for a long time and numerous EGFR inhibitors are under development, but to date only lapatinib has been approved by FDA for MBC. Lapatinib when combined with capecitabine has shown clinical efficacy in heavily pre-treated HER-2 overexpressing breast cancer patients. A number of other small molecule inhibitors like canertinib and HKI-272 are under development and numerous clinical trials are being conducted to assess the efficiency of these agents but unfortunately only limited gains have been achieved when these agents are used as monotherapy. Among the available therapies, TKIs appear to be better as compared to antibodies targeting EGFRs, in terms of side effects, cost-effectiveness and efficient delivery to tumor sites. However, a big challenge still lies ahead for medicinal chemists and pharmacologists for want of improved strategies, synthesis and identification of novel chemical entities targeting EGFR/HER-2. Medicinal Research Reviews 2012, 32(1), 166–215 The major obstacles in development of successful ErbB targeted therapy include the redundancy of cellular pathways, the concomitant aberrations and involvement of multiple cross talk mechanisms in cancer cells which eventually lead to the development of resistance. Therefore, it is likely that multiple targets need to be addressed for maximal clinical effects and to minimize development of resistance. There are evidences to show that EGFR/HER-2 inhibitors hold greater promise when used in combination with radiation or chemotherapy compared to either treatment alone. So the combination therapy may involve use of EGFR inhibitors with HER-2 inhibitors like trastuzumab with lapatinib that has shown promising results in clinic. The crosstalk between estrogen receptor α and EGFR/HER-2 provides a rationale for combining antiestrogens with HER-2 targeting therapies. Till date only tamoxifen and fulvestrant have been used for ER positive tumors.307 There is also a need for introducing newer antiestrogens with improved profile e.g. toremefine, raloxifene, into combination therapy. Similarly, IGFR1 inhibitors can also be used in combination with EGFR/HER-2 inhibitors.308 Crosstalk between VEGFR and EGFR/HER-2 pathways provides rationale for combining anti-VEGF antibodies or VEGFR tyrosine kinase inhibitors with ErbB inhibitors. Clinical trials are underway to investigate the efficacy of these combination therapies in breast cancer. EGFR/HER-2 inhibitors can also be used with hsp90 antagonists that leads to proteolysis of EGFR/HER-2 or with the inhibitors of PI3K/Akt/mTOR pathway.64-65 Future strategies may also be designed towards the combination of ErbB inhibitors with integrin antagonists to be utilized for enhanced outcome in MBC patients.309 In case of triple negative cancers having EGFR positive status, the PARP inhibitors combined with EGFR inhibitors, may be another ray of hope. Currently, the challenge remains ahead to formulate an appropriate combination strategy to maximize the treatment outcome. On the other hand, it is highly desirable to explore various resistance mechanisms as well. Another recent approach to combat development of resistance involves targeting the breast cancer stem cells.310 This subset of breast cancer cells has the unique property to proliferate and develop new tumors that might be resistant to the ongoing therapy. So it would be advantageous to target these stem cells in contrast to merely treating the symptoms of the disease. Lapatinib treatment in a neo-adjuvant setting has shown to decrease the number of breast cancer stem cells and in tumor biopsies as opposed to chemotherapy which led to an increase.294-295 Therefore, the agents like lapatinib which are less toxic and more efficacious could be of significant importance in the treatment of breast cancer. It is also important to identify the genes that trigger molecular pathways involved in chemoresistance, tumor formation and malignant cell self - renewal associated with the cancer stem cells. New therapies to inhibit breast cancer stem cells would be of vital importance and if these are not targeted, any targeted therapy would be of limited efficacy. Important work also needs to be done to identify patients who will benefit from targeting the ErbB family receptors. This requires the molecular characterization of the tumor of every individual patient and also the identification of biological markers predictive of response or development of resistance to the targeted agents. Development of more precise and accurate methods for the evaluation of expression levels of EGFR/HER-2 is highly mandatory. The selection of appropriate dose and schedule with new agents entering the clinic and implementation of the appropriate combination therapy with conventional therapies as well as with other anti-signaling agents, will aid to the success of upcoming candidate drugs. With the advancement of techniques in genomics and proteomics analysis, it is hoped that future research will also be directed towards the identification of signature genes associated with activation of specific signaling pathway.295 This would help in the identification of the major pathway involved in the tumorigenesis in any case which would lead to the formulation of more specific and appropriate individualized targeted therapy. ACKNOWLODGEMENT CDRI Communication No. 7932 Medicinal Research Reviews 2012, 32(1), 166–215 ABBREVIATIONS AIB1 amplified in breast and ovarian cancer-1 BM brain metastasis CISH chromogenic in situ hybridisation CR complete response c/w combination with DFS disease-free survival EGF epidermal growth factor EGFR epidermal growth factor receptor ERα estrogen receptor α FasL fas ligand FISH fluorescent in situ hybridization FKHR forkhead in rhabdomyosarcoma Grb growth factor receptor-bound protein GSK glycogen synthase kinase HER-2 herceptin-2 IGFR insulin –like growth factor receptor IHC immunohistochemistry JAK janus kinase LBD ligand binding domain MAPK mitogen activated protein kinase MBC metastatic breast cancer MS median survival mTOR mammalian target of rapamycin NRG neuregulin NFκB nuclear factor kappa B ORR overall response rate OS overall survival PFS progression free survival PI3K phosphotidyl inositol 3 kinase PKC Protein Kinase C PLCγ phospho lipase C γ PR partial response PTEN phosphatase and tensin homolog deleted on chromosome 10 RR response rate SOS sf sevenless guanine nucleotide exchange factor STAT signal transducers and activators of transcription TTP time to progression VEGFR vascular endothelial growth factor receptor REFERENCES 1. 2. 3. Chu D, Lu J. Novel Therapies in Breast Cancer: What is New from ASCO 2008. J Hematol Oncol 2008; 1:16. Bange J, Zwick E, Ullrich A. Molecular targets for breast cancer therapy and prevention. Nat Med 2001; 7(5):548-552. Carter SK. Single and combination nonhormonal chemotherapy in breast cancer. Cancer 1972; 30(6):1543–1555. Medicinal Research Reviews 2012, 32(1), 166–215 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. Fossati R, Confalonieri C, Torri V, Ghislandi E, Penna A, Pistotti V, Tinazzi A, Liberati A. Cytotoxic and hormonal treatment for metastatic breast cancer: a systematic review of published randomized trials involving 31,510 women. J Clin Oncol 1998; 16(10):3439–3460. Lanni JS, Lowe SW, Licitra EJ, Liu JO, Jacks T. p53-independent apoptosis induced by paclitaxel through an indirect mechanism. Proc Natl Acad Sci U S A 1997; 94(18):9679–9683. Tamoxifen for early breast cancer: an overview of the randomised trials. Early Breast Cancer Trialists' Collaborative Group. Lancet 1998; 351(9114):1451-1467. Perou CM, Sorlie T, Eisen MB, van de Rijn M, Jeffrey SS, Rees CA, Pollack JR, Ross DT, Johnsen H, Akslen LA, Fluge O, Pergamenschikov A, Williams C, Zhu SX, Lonning PE, Borresen-Dale AL, Brown PO, Botstein D. Molecular portraits of human breast tumours. Nature 2000;406(6797):747752. Sotiriou C, Neo SY, McShane LM, Korn EL, Long PM, Jazaeri A, Martiat P, Fox SB, Harris AL, Liu ET. Breast cancer classification and prognosis based on gene expression profiles from a populationbased study. Proc Natl Acad Sci U S A 2003;100(18):10393-10398. Sorlie T, Tibshirani R, Parker J, Hastie T, Marron JS, Nobel A, Deng S, Johnsen H, Pesich R, Geisler S, Demeter J, Perou CM, Lonning PE, Brown PO, Borresen-Dale AL, Botstein D. Repeated observation of breast tumor subtypes in independent gene expression data sets. Proc Natl Acad Sci U S A 2003;100(14):8418-8423. Santen RJ. Inhibition of aromatase: insights from recent studies. Steroids 2003;68: 559–567. Johnston SR, Dowsett M. Aromatase inhibitors for breast cancer: lessons from the laboratory. Nat Rev Cancer 2003;3(11):821-831. Sorlie T, Perou CM, Tibshirani R, Aas T, Geisler S, Johnsen H, Hastie T, Eisen MB, van de Rijn M, Jeffrey SS, Thorsen T, Quist H, Matese JC, Brown PO, Botstein D, Eystein Lonning P, BorresenDale AL. Gene expression patterns of breast carcinomas distinguish tumor subclasses with clinical implications. Proc Natl Acad Sci U S A 2001;98(19):10869-10874. Nielsen TO, Hsu FD, Jensen K, Cheang M, Karaca G, Hu Z, Hernandez-Boussard T, Livasy C, Cowan D, Dressler L, Akslen LA, Ragaz J, Gown AM, Gilks CB, van de Rijn M, Perou CM. Immunohistochemical and clinical characterization of the basal-like subtype of invasive breast carcinoma. Clin Cancer Res 2004;10(16):5367-5374. Diaz LK, Cryns VL, Symmans F, Sneige N. Triple negative breast carcinoma and the basal phenotype: from expression profiling to clinical practice. Adv Anat Pathol 2007; 14: 419–430. Anders C, Carey LA. Understanding and treating triple-negative breast cancer. Oncology (Williston Park) 2008; 22(11):1233-1239; discussion 1239-1240, 1243. Reis-Filho JS, Tutt AN. Triple negative tumours: a critical review. Histopathology 2008;52(1):108118. Breur A, Kandel M, Fisseler-Eckhoff A, Sutter C, Schawaab E, Luck HJ, duBois A. BRCA1 germline mutation in a woman with metaplastic squamous cell breast cancer. Onkologie 2007;30:316-318. Young SR, Pilarski RT, Donenberg T, Shapiro C, Hammond LS, Miller J, Brooks KA, Cohen S, Tenenholz B, Desai D, Zandvakili I, Royer R, Li S, Narod SA. The prevalence of BRCA1 mutations among young women with triple-negative breast cancer. BMC Cancer 2009;9:86. Drew Y, Plummer R. The emerging potential of poly(ADP-ribose) polymerase inhibitors in the treatment of breast cancer. Curr Opin Obstet Gynecol 2010;22(1):66-71. Pal SK, Mortimer J. Triple-negative breast cancer: novel therapies and new directions. Maturitas 2009;63(4):269-274. Drew Y, Calvert H. The potential of PARP inhibitors in genetic breast and ovarian cancers. Ann N Y Acad Sci 2008;1138:136-145. Fong PC, Boss DS, Yap TA, Tutt A, Wu P, Mergui-Roelvink M, Mortimer P, Swaisland H, Lau A, O'Connor MJ, Ashworth A, Carmichael J, Kaye SB, Schellens JH, de Bono JS. Inhibition of Medicinal Research Reviews 2012, 32(1), 166–215 23. 24. 25. 26. 27. 28. 29. 30. 31. poly(ADP-ribose) polymerase in tumors from BRCA mutation carriers. N Engl J Med 2009;361(2):123-134. Siziopikou KP, Cobleigh M. The basal subtype of breast carcinomas may represent the group of breast tumors that could benefit from EGFR-targeted therapies. Breast 2007;16(1):104-107. Siziopikou KP, Ariga R, Proussaloglou KE, Gattuso P, Cobleigh M. The challenging estrogen receptor-negative/ progesterone receptor-negative/HER-2-negative patient: a promising candidate for epidermal growth factor receptor-targeted therapy? Breast J 2006;12(4):360-362. McGuire W, Clark G. Prognostic factors and treatment decisions in axillary-node-negative breast cancer. N. Engl. J. Med.1992; 326:1756–1762. Miyoshi Y, Akazawa K, Kamigaki S, Ueda S, Yanagisawa S, Inoue T, Yamamura J, Taguchi T, Tamaki Y, Noguchi S. Prognostic significance of intra-tumoral estradiol level in breast cancer patients. Cancer Lett 2004; 216:115–121. Fuqua SA, Cui Y. Estrogen and progesterone receptor isoforms:clinical significance in breast cancer. Breast Cancer Res. Treat. 2004; 87:3–S10. Clarke R, Skaar TC, Bouker KB, Davis N, Lee YR, Welch JN, Leonessa F. Molecular and pharmacological aspects of antiestrogen resistance. J. Steroid Biochem. Mol. Biol. 2001; 76:71–84. Riggs BL, Hartmann LC. Selective Estrogen-Receptor Modulators — Mechanisms of Action and Application to Clinical Practice. N Engl J Med 2003; 348(7):618-629. Lee WL, Cheng MH, Chao HT, Wang PH. The role of selective estrogen receptor modulators on breast cancer: from tamoxifen to raloxifene. Taiwan J Obstet Gynecol 2008;47(1):24-31. Cole MP, Jones CT, Todd ID. A new anti-oestrogenic agent in late breast cancer. An early clinical appraisal of ICI46474. Br J Cancer 1971; 25:270–275. 32. Peto R, Boreham J, Clarke M, Davies C, Beral V. UK and USA breast cancer deaths down 25% in year 2000 at ages 20–69 years. Lancet 2000; 355(1822):592-593. 33. Gradishar WJ. Tamoxifen- what next? Oncologist 2004; 9:378-384. 34. Tamoxifen for early breast cancer. Early Breast Cancer Trialists’ Collaborative Group. Cochrane Database Syst. 2004; Rev1: CD000486. 35. Paridaens R, Sylvester RJ, Ferrazzi E, Legros N, Leclercq G, Heuson JC. Clinical signiﬁcance of the 36. 37. 38. 39. 40. 41. quantitative assessment of estrogen receptors in advanced breast cancer. Cancer 1980; 46(12 Suppl):2889–2895. Lippman ME, Allegra JC. Quantitative estrogen receptor analyses: the response to endocrine and cytotoxic chemotherapy in human breast cancer and the disease-free interval. Cancer 1980; 46(12 Suppl):2829–2834. Campbell FC, Blamey RW, Elston CW, Morris AH, Nicholson RI, Grifﬁths K, Haybittle JL.Quantitative oestradiol receptor values in primary breast cancer and response of metastases to endocrine therapy. Lancet 1981; 2(8259):1317–1319. Stewart J, King R, Hayward J, Rubens R. Estrogen and progesterone receptors: correlation of response rates, site and timing of receptor analysis. Breast Cancer Res Treat 1982; 2(3):243–250. Ingle JN, Twito DI, Schaid DJ, Cullinan SA, Krook JE, Mailliard JA, Marschke RF, Long HJ, Gerstner JG, Windschitl HE. Randomized clinical trial of tamoxifen alone or combined with fluoxymesterone in postmenopausal women with metastatic breast cancer. J Clin Oncol 1988; 6(5):825-831. Veronesi U, Maisonneuve P, Costa A, Saccini V, Maltoni C, Robertson C. Prevention of breast cancer with Tamoxifen: preliminary findings from Italian randomized trial among hysterectomised women. Lancet 1998; 352:, 93–97. Fisher B, Constantino JP, Wickerham DL, Redmond CK, Kavanah M, Cronin WM, Vogel V, Robidoux A, Dimitrov J, Atkins J, Daly M, Wieand S, Tan-Chiu E, Ford L, Woolmark H. Tamoxifen for prevention of breast cancer: report of the national surgical adjuvant breast and bowel project P-1 study. J. Natl. Cancer Inst. 1998; 90:1371–1388. Medicinal Research Reviews 2012, 32(1), 166–215 42. Cuzick J, Powles T, Veronesi U, Forbes J, Edwards R, Ashley S, Boyle P. Overview of the main 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. outcomes in breast cancer prevention trials. Lancet 2003;3 61(9354):296–300. Fisher B, Constantino JP, Wickerham DL, Redmond CK, Kavanah M, Cronin WM, Vogel V, Robidoux A, Dimitrov J, Atkins J, Daly M, Wieand S, Tan-Chiu E, Ford L, Woolmark H. Tamoxifen for prevention of breast cancer: report of the national surgical adjuvant breast and bowel project P-1 study. J Natl Cancer Inst 1998; 90:1371–1388. MacGregor JI, Jordan VC. Basic guide to the mechanism of antiestrogen action. Pharmacol Rev 1998; 50:151–196. Vogel VG, Costantino JP, Wickerham DL, Cronin WM, Cecchini RS, Atkins JN,Bevers TB, Fehrenbacher L, Pajon ER, Jr., Wade JL, 3rd, Robidoux A, Margolese RG, James J, Lippman SM, Runowicz CD, Ganz PA, Reis SE, McCaskill-Stevens W, Ford LG, Jordan VC, Wolmark N. Effects of tamoxifen vs raloxifene on the risk of developing invasive breast cancer and other disease outcomes: the NSABP Study of Tamoxifen and Raloxifene (STAR) P-2 trial. Jama 2006; 295(23):2727-2741. Howell A, Defriend D, Anderson E. Mechanism of response and resistance to endocrine therapy for breast cancer and the development of new treatments. Rev Endocr-Related Cancer 1993; 43:5-21. Ring A, Dowsett M. Mechanisms of tamoxifen resistance. Endocr Relat Cancer 2004; 11(4):643-658. Frasor J, Danes JM, Komm B, Chang KC, Lyttle CR, Katzenellenbogen BS. Profiling of estrogenup- and down-regulated gene expression in human breast cancer cells: Insights into gene networks and pathways underlying estrogenic control of proliferation and cell phenotype. Endocrinology 2003; 144:4562–4574. Nicholson RI, Staka C, Boyns F, Hutcheson IR, Gee JMW. Growth factor-driven mechanisms associated with resistance to estrogen deprivation in breast cancer: new opportunities for therapy. Endocr Relat Cancer 2004; 11(4):623–641. McClelland RA, Barrow D, Madden TA, Dutkowski CM, Pamment J, Knowlden JM, Gee JM, Nicholson RI. Enhanced epidermal growth factor receptor signaling in MCF7 breast cancer cells after long-term culture in the presence of the pure antiestrogen ICI 182,780 (Faslodex). Endocrinology 2001; 142(7):2776-2788. Anzick SL, Kononen J, Walker RL, Azorsa DO, Tanner MM, Guan XY, Sauter G, Kallioniemi OP, Trent JM, Meltzer PS. AIB1, a steroid receptor coactivator amplified in breast and ovarian cancer. Science 1997; 277(5328):965-968. Lavinsky RM, Jepsen K, Heinzel T, Torchia J, Mullen TM, Schiff R, Del-Rio AL, Ricote M, Ngo S, Gemsch J, Hilsenbeck SG, Osborne CK, Glass CK, Rosenfeld MG, Rose DW. Diverse signaling pathways modulate nuclear receptor recruitment of N-CoR and SMRT complexes. Proc Natl Acad Sci U S A 1998; 95(6):2920-2925. Dickson RB, Lippman ME. Growth factors in breast cancer. Endocr Rev 1995; 16(5):559-589. Paik S, Hartmann DP, Dickson RB, Lippman ME. Antiestrogen resistance in ER positive breast cancer cells. Breast Cancer Res Treat 1994; 31(2-3):301-307. Osborne CK, Shou J, Massarweh S, Schiff R. Crosstalk between estrogen receptor and growth factor receptor pathways as a cause for endocrine therapy resistance in breast cancer. Clin Cancer Res 2005; 11(2 Pt 2):865s-870s. Knowlden JM, Hutcheson IR, Jones HE, Madden T, Gee JM, Harper ME, Barrow D, Wakeling AE, Nicholson RI. Elevated levels of epidermal growth factor receptor/c-erbB2 heterodimers mediate an autocrine growth regulatory pathway in tamoxifen-resistant MCF-7 cells. Endocrinology 2003;144(3):1032-1044. Shou J, Massarweh S, Osborne CK, Wakeling AE, Ali S, Weiss H, Schiff R. Mechanisms of tamoxifen resistance: increased estrogen receptor-HER2/neu cross-talk in ER/HER2-positive breast cancer. J Natl Cancer Inst 2004; 96(12):926-935. Medicinal Research Reviews 2012, 32(1), 166–215 58. Britton DJ, Hutcheson IR, Knowlden JM, Barrow D, Giles M, McClelland RA, Gee JM, Nicholson 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. RI. Bidirectional cross talk between ERalpha and EGFR signalling pathways regulates tamoxifenresistant growth. Breast Cancer Res Treat 2006; 96(2):131-146. Gswind A, Fischer OM, Ullrich A. The discovery of receptors tyrosine kinases: targets for cancer therapy. Nat Rev Cancer 2004; 4:361-370. Prendergast GC. Farnesyl transferase inhibitors: antineoplastic mechanism and clinical prospects. Curr Opin Cell Biol 2000; 12:166-173. Faria M, Spiller DG, Dubertret C, Nelson JS, White MR, Scherman D, Helene C, Giovannangeli C. Phosphoramidate oligonucleotides as potent antisense molecules in cells and in vivo. Nat Biotechnol 2001; 19(1):40-44. Lavelle F. [New anticancer molecules: drugs for tomorrow?]. Bull Cancer 1999; 86(1):91-95. Carraway H, Hidalgo M. New Targets for therapy of breast cancer: mammalian target of rapamycin (mTOR) antagonists. Breast Cancer Res 2004; 6(5):219-224. Adams J. Proteasome Inhibitors as anticancer drugs. Curr Opin Oncol 2002; 14(6):628-634. Brown J, Von Roenn J, O’Regan R, Bergan R, Badve S, Rademaker A, Feehan S, Petersen J, Patton M, Gradishar W. A phase II study of the proteasome inhibitor PS-341 in patients(pts) with metastatic breast cancer (MBC). J Clin Oncol (ASCO Meeting abstract) 2004; 22 Suppl 14;546. Mendelsohn J, Baselga J. The EGF receptor family as targets for cancer therapy. Oncogene 2000;19(56):6550-6565. Jezdic S, Popov I. EGF receptor as a therapeutic target in oncology Archive of Oncology 2005; 13 Suppl 1:53-55. Lewis S, Locker A, Todd JH, Bell JA, Nicholson R, Elston CW, Blamey RW, Ellis IO. Expression of epidermal growth factor receptor in breast carcinoma. J Clin Pathol 1990; 43(5):385-389. Chrysogelos SA, Yarden RI, Lauber AH, Murphy JM. Mechanisms of EGF receptor regulation in breast cancer cells. Breast Cancer Res Treat 1994;31(2-3):227-236. Gershtein ES, Ermilova VD, Kuz'mina ZV, Kuzlinskii NE, Letiagin VP. [Expression of epidermal growth factor receptors and their ligands in malignant tumors of the breast]. Vestn Ross Akad Med Nauk 1996(3):15-19. Biswas DK, Cruz AP, Gansberger E, Pardee AB. Epidermal growth factor-induced nuclear factor kappa B activation: A major pathway of cell-cycle progression in estrogen-receptor negative breast cancer cells. Proc Natl Acad Sci U S A 2000; 97(15):8542-8547. Bolufer P, Lluch A, Molina R, Alberola V, Vazquez C, Padilla J, Garcia-Conde J, Llopis F, Guillem V. Epidermal growth factor in human breast cancer, endometrial carcinoma and lung cancer. Its relationship to epidermal growth factor receptor, estradiol receptor and tumor TNM. Clin Chim Acta 1993;215(1):51-61. Harari D, Yarden Y. Molecular mechanisms underlying ErbB2/HER2 action in breast cancer. Oncogene 2000; 19(53):6102-6114. Jardines L, Weiss M, Fowble B, Greene M. neu(c-erbB-2/HER2) and the epidermal growth factor receptor (EGFR) in breast cancer. Pathobiology 1993;61(5-6):268-282. Bates SE, Fojo T. Epidermal Growth Factor Receptor Inhibitors: A Moving Target? Clin Cancer Res 2005; 11(20):7203-7205. Klijn JG, Berns PM, Schmitz PI, Foekens JA. The clinical significance of epidermal growth factor receptor (EGF-R) in human breast cancer: a review on 5232 patients. Endocr Rev 1992; 13:3-17. Tsutsui S, Ohno S, Murakami S, Hachitanda Y, Oda S: Prognostic value of epidermal growth factor receptor (EGFR) and its relationship to the estrogen receptor status in 1029 patients with breast cancer. Breast Cancer Res Treat 2002; 71:67-75. Slamon DJ, Clark GM, Wong SG, Levin WJ, Ullrich A, McGuire WL. Human breast cancer: correlation of relapse and survival with amplification of the HER-2/neu oncogene. Science 1987; 235:177-182. Medicinal Research Reviews 2012, 32(1), 166–215 79. Garrett TP, McKern NM, Lou M, Frenkel MJ, Bentley JD, Lovrecz GO, Elleman TC, Cosgrove LJ, 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. Ward CW. Crystal structure of the first three domains of the type-1 insulin-like growth factor receptor. Nature 1998; 394(6691):395-399. Garrett TP, McKern NM, Lou M, Elleman TC, Adams TE, Lovrecz GO, Zhu HJ, Walker F, Frenkel MJ, Hoyne PA, Jorissen RN, Nice EC, Burgess AW, Ward CW. Crystal structure of a truncated epidermal growth factor receptor extracellular domain bound to transforming growth factor alpha. Cell 2002;110(6):763-773. Ogiso H, Ishitani R, Nureki O, Fukai S, Yamanaka M, Kim JH, Saito K, Sakamoto A, Inoue M, Shirouzu M, Yokoyama S. Crystal structure of the complex of human epidermal growth factor and receptor extracellular domains. Cell 2002;110(6):775-787. Aifa S, Aydin J, Nordvall G, Lundstrom I, Svensson SP, Hermanson O. A basic peptide within the juxtamembrane region is required for EGF receptor dimerization. Exp Cell Res 2005; 302(1):108114. Mineo C, Gill GN, Anderson RG. Regulated migration of epidermal growth factor receptor from caveolae. J Biol Chem 1999; 274(43):30636-30643. Gotoh N, Tojo A, Hino M, Yazaki Y, Shibuya M. A highly conserved tyrosine residue at codon 845 within the kinase domain is not required for the transforming activity of human epidermal growth factor receptor. Biochem Biophys Res Commun 1992;186(2):768-774. Salomon DS, Brandt R, Ciardiello F, Normanno N. Epidermal growth factor-related peptides and their receptors in human malignancies. Crit Rev Oncol/Hematol 1995; 19:183–232. Pawson T. Protein modules and signalling networks. Nature 1995; 373:573–580. Carpenter G. The EGF receptor: A nexus for trafficking and signaling. Bioassays 2000; 22:697–707. Maruta H, Burgess AW. Regulation of the Ras signalling network. Bioessays 1994; 16:489–496. Luo J, Manning B, Cantley L. Targeting the PI3K-Akt pathway in human cancer: Rationale and promise. Cancer Cell 2003; 4:257–262. Vivanco I, Sawyers CL. The phosphatidyl inositol 3-kinase Akt pathway in human cancer. Nat Rev Cancer 2002; 2:489–501. Cantley LC, Neel BG. New insights into tumor suppression: PTEN suppresses tumor formation by restraining the phosphoinositide 3-kinase/akt pathway. Proc Natl Acad Sci U S A 1999; 96:4240– 4245. Falasca M, Logan SK, Lehto VP, Baccante G, Lemmon MA, Schlessinger J. Activation of phospholipase C gamma by PI 3-kinase-induced PH domain-mediated membrane targeting. Embo J 1998; 17(2):414–422. Normanno N, Bianco C, De Luca A, Salomon DS. The role of EGF-related peptides in tumor growth. Front Biosci 2001; 6:D685–707. Olayioye MA, Neve RM, Lane HA, Hynes NE. The ErbB signalling network: receptor dimerisation in development and cancer. EMBO Journal 2000;19: 3159–3167.Shoyab M, Plowman GD, McDonald VL, Bradley JG , Todaro GJ. Structure and function of human amphiregulin: a member of the epidermal growth factor family. Science 1989; 243:1074–1076. Shoyab M, Plowman GD, McDonald VL, Bradley JG, Todaro GJ. Structure and function of human amphiregulin: a member of the epidermal growth factor family. Science 1989; 243:1074–1076. Carpenter G & Cohen S 1990 Epidermal growth factor. J Biol Chem 1990; 265:7709–7712. Riese DJ, Kim ED, Elenius K, Buckley S, Klagsbrun M, Plowman GD, Stem DF. The epidermal growth factor receptor couples transforming growth factor-alpha, heparin-binding epidermal growth factor like factor, and amphiregulin to neu, ErbB-3, and ErbB-4. J Biol Chem 1996; 271(33):20047– 20052. Elenius K, Paul S, Allison G, Sun J, Klagsbrun M. Activation of HER4 by heparin-binding EGF-like growth factor stimulates chemotaxis but not proliferation. EMBO Journal 1997; 16:1268–1278. Medicinal Research Reviews 2012, 32(1), 166–215 99. Shelly M, Pinkas-Kramarski R, Guarino BC, Waterman H, Wang LM, Lyass L, Alimandi M, Kuo A, Bacus SS, Pierce JH, Andrews GC, Yarden Y. Epiregulin is a potent pan-ErbB ligand that preferentially activates heterodimeric receptor complexes. J Biol Chem 1998; 273:10496–10505. 100. Zhang D, Sliwkowski MX, Mark M, Frantz G, Akita R, Sun Y, Hillan K, Crowley C, Bush J, Godowski PJ. Neuregulin 3 (NRG3): a novel neural tissue-enriched protein that binds and activated ErbB4. Proc Natl Acad Sci U S A 1997; 94: 9562–9567. 101. Harari D, Tzahar E, Romano J, Shelly M, Pierce JH, Andrews GC, Yarden Y. Neuregulin-4: a novel growth factor that acts through the ErbB-4 receptor tyrosine kinase. Oncogene 1999; 18:2681–2689. 102. Normanno N, De Luca A, Bianco C, Strizzi L, Mancino M, Maiello MR, Carotenuto A, De Feo G, Caponigro F, Salomon DS. Epidermal growth factor receptor (EGFR) signaling in cancer. Gene 2006; 366(1):2-16. 103. Sato JD, Kawamoto T, Le AD. Biological effect in vitro of monoclonal antibodies to human EGF receptors. Mol Biol Med 1983; 1:511-529. 104. Masui H, Kawamoto T, Sato JD. Growth inhibition of human tumor cells in athymic mice by antiepidermal growth factor receptor monoclonal antibodies. Cancer Res 1984; 44:1002-1007. 105. Mendelsohn J. Targeting the epidermal growth factor receptor for cancer therapy. J Clin Oncol 2002;20(18 Suppl):1s-13s. 106. Lynch TJ, Bell DW, Sordella R, Gurubhagavatula S, Okimoto RA, Brannigan BW, Harris PL, Haserlat SM, Supko JG, Haluska FG, Louis DN, Christiani DC, Settleman J, Haber DA. Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to Gefitinib. N Engl J Med 2004; 350(21):2129-2139. 107. Nishikawa R, Ji XD, Harmon RC, Lazar CS, Gill GN, Cavenee WK, Huang HJ. A mutant epidermal growth factor receptor common in human glioma confers enhanced tumorigenicity. Proc Natl Acad Sci U S A 1994; 91(16):7727–7731. 108. Kuan CT, Wikstrand CJ, Bigner DD: EGF mutant receptor vIII as a molecular target in cancer therapy. Endocr Relat Cancer 2001; 8:83-96. 109. Moscatello DK. Frequent expression of a mutant epidermal growth factor receptor in multiple human tumors. Cancer Res 1995; 55:5536-5539. 110. Paez JG, Janne PA, Lee JC, Tracy S, Greulich H, Gabriel S, Herman P, Kaye FJ, Lindeman N, Boggon TJ, Naoki K, Sasaki H, Fujii Y, Eck MJ, Sellers WR, Johnson BE, Meyerson M. EGFR mutations in lung cancer: correlation with clinical response to Gefitinib therapy. Science 2004; 304(5676):1497-1500. 111. Wong AJ, Ruppert JM, Bigner SH, Grzeschik CH, Humphrey PA, Bigner DS, Vogelstein B. Structural alterations of the epidermal growth factor receptor gene in human gliomas. Proc Natl Acad Sci 1992; 89(7):2965–2969. 112. Ekstrand AJ, Longo N, Hamid ML, Olson JJ, Liu L, Collins VP, James CD. Functional characterization of an EGF receptor with a truncated extracellular domain expressed in glioblastomas with EGFR gene amplification. Oncogene 1994; 9(8):2313–2320 113. Grandis JR, Tweardy DJ. Elevated levels of transforming growth factor alpha and epidermal growth factor receptor messenger RNA are early markers of carcinogenesis in head and neck cancer. Cancer Res 1993; 53(15):3579–3584. 114. De Laurentiis M, Arpino G, Massarelli E, Ruggiero A, Carlomagno C, Ciardiello F, Tortora G, D’Agostino D, Caputo F, Cancello G, Montagna E, Malorni L, Zinno L, Lauria R, Bianco AR, De Placido S. A meta-analysis on the interaction between expression and response to endocrine treatment in advanced breast cancer. Clin Cancer Res 2005; 11:4741–4748. 115. Arpino G, Green SJ, Allred DC, Lew D, Martino S, Osborne CK, Elledge RM. HER-2 amplification, HER-1 expression, and tamoxifen response in estrogen receptor-positive metastatic breast cancer: a southwest oncology group study. Clin Cancer Res 2004; 10:5670–5676. 116. Ellis M. Overcoming endocrine therapy resistance by signal transduction inhibition. Oncologist 2004; 9(Suppl 3):20–26. Medicinal Research Reviews 2012, 32(1), 166–215 117. Levin ER, Pietras RJ. Estrogen receptors outside the nucleus in breast cancer. Breast Cancer Res Treat 2008;108(3):351-361. 118. Lin NU, Winer EP. New targets for therapy in breast cancer Small molecule tyrosine kinase inhibitors Breast Cancer Res 2004; 6(5):204-210. 119. Osborne CK, Schiff R. Estrogen-receptor biology: continuing progress and therapeutic implications. J Clin Oncol 2005; 23(8):1616–1622. 120. Osborne CK, Bardou V, Hopp TA, Chamness GC, Hilsenbeck SG, Fuqua SA, Wong J, Allred DC, Clark GM, Schiff R. Role of the estrogen receptor coactivator AIB1 (SRC-3) and HER-2/neu in tamoxifen resistance in breast cancer. J Natl Cancer Inst 2003;95(5):353-361. 121. Razandi M, Oh P, Pedram A, Schnitzer J, Levin ER. ERs associate with and regulate the production of caveolin: implications for signaling and cellular actions. Mol Endocrinol 2002; 16:100–115. 122. Pedram A, Razandi M, Sainson RC, Kim JK, Hughes CC, Levin ER. A conserved mechanism for steroid receptor translocation to the plasma membrane. J Biol Chem 2007;282:22278–22288. 123. Marquez DC, Chen HW, Curran EM, Welshons WV, Pietras RJ. Estrogen receptors in membrane lipid rafts and signal transduction in breast cancer. Mol Cell Endocrinol 2006; 246:91–100. 124. Aronica SM, Kraus WL, Katzenellenbogen BS. Estrogen action via the cAMP signaling pathway: stimulation of adenylate cyclase and cAMP-regulated gene transcription. Proc Natl Acad Sci U S A 1994;91(18):8517-8521. 125. Kahlert S, Nuedling S, van Eickels M, Vetter H, Meyer R, Grohe C. Estrogen receptor alpha rapidly activates the IGF-1 receptor pathway. J Biol Chem 2000;275(24):18447-18453. 126. Simoncini T, Hafezi-Moghadam A, Brazil DP, Ley K, Chin WW, Liao JK. Interaction of oestrogen receptor with the regulatory subunit of phosphatidylinositol-3-OH kinase. Nature 2000;407(6803):538-541. 127. Song RX, McPherson RA, Adam L, Bao Y, Shupnik M, Kumar R, Santen RJ. Linkage of rapid estrogen action to MAPK activation by ERalpha-Shc association and Shc pathway activation. Mol Endocrinol 2002;16(1):116-127. 128. MacGregor Schafer J, Liu H, Levenson AS, Horiguchi J, Chen Z, Jordan VC. Estrogen receptor alpha mediated induction of the transforming growth factor alpha gene by estradiol and 4hydroxytamoxifen in MDA-MB-231 breast cancer cells. J Steroid Biochem Mol Biol 2001;78(1):4150. 129. Wilson MA, Chrysogelos SA. Identification and characterization of a negative regulatory element within the epidermal growth factor receptor gene first intron in hormone-dependent breast cancer cells. J Cell Biochem 2002;85(3):601-614. 130. Russell KS, Hung MC. Transcriptional repression of the neu protooncogene by estrogen stimulated estrogen receptor. Cancer Res 1992;52(23):6624-6629. 131. Kato S, Endoh H, Masuhiro Y, Kitamoto T, Uchiyama S, Sasaki H, Masushige S, Gotoh Y, Nishida E, Kawashima H. Activation of the estrogen receptor through phosphorylation by mitogen-activated protein kinase. Science 1995; 270:1491–1494. 132. Bunone G, Briand PA, Miksicek RJ, Picard D. Activation of the unliganded estrogen receptor by EGF involves the MAP kinase pathway and direct phosphorylation. Embo J 1996; 15:2174–2183. 133. Joel PB, Smith J, Sturgill TW, Fisher TL, Blenis J, Lannigan DA. pp90rsk1 regulates estrogen receptor-mediated transcription through phosphorylation of Ser-167. Mol Cell Biol 1998; 18:1978– 1984. 134. Coutts AS, Murphy LC. Elevated mitogen-activated protein kinase activity in estrogennonresponsive human breast cancer cells. Cancer Res 1998; 58(18): 4071–4074. 135. Shim WS, Conaway M, Masamura S, Yue W, Wang JP, Kmar R, Santen RJ. Estradiol hypersensitivity and mitogen activated protein kinase expression in long-term estrogen deprived human breast cancer cells in vivo. Endocrinology 2000; 141: 396–405. Medicinal Research Reviews 2012, 32(1), 166–215 136. Lavinsky RM, Jepsen K, Heinzel T, Torchia J, Mullen TM, Schiff R, Del-Rio AL, Ricote M, Ngo S, Gemsch J, Hilsenbeck SG, Osborne CK, Glass CK, Rosenfeld MG, Rose DW. Diverse signaling pathways modulate nuclear receptor recruitment of N-CoR and SMRT complexes. Proc Natl Acad Sci U S A 1998; 95(6): 2920–2925. 137. Font de Mora J, Brown M. AIB1 is a conduit for kinase mediated growth factor signaling to the estrogen receptor. Mol Cell Biol 2000; 20:5041–5047. 138. Hong SH, Privalsky ML. The SMRT corepressor is regulated by a MEK-1 kinase pathway: inhibition of corepressor function is associated with SMRT phosphorylation and nuclear export. Mol Cell Biol 2000; 20:6612–6625. 139. Wu RC, Qin J, Hashimoto Y, Wong J, Xu J, Tsai SY, Tsai MJ, O’Malley BW. Regulation of SRC-3 (pCIP/ACTR/AIB-1/RAC-3/TRAM-1) Coactivator activity by I kappa B kinase. Mol Cell Biol 2002; 22:3549–3561. 140. Ross JS, Fletcher JA, Bloom KJ, Linette GP, Stec J, Symmans WF, Pusztai L, Hortobagyi GN. Targeted Therapy in Breast Cancer :the HER-2/neu gene and protein. Mol Cell Proteomics 2004; 3(4):379-398. 141. Levitzki A. EGF receptor as a therapeutic target. Lung Cancer 2003; 41:S9-S14. 142. Pauletti G, Godolphin W, Press MF, Slamon DJ. Detection and quantifation of HER-2/neu gene amplification in human breast cancer archival material using fluorescence in situ hybridization. Oncogene 1996; 13(1):63–72. 143. Hynes NE, Gerber HA, Saurer S, Groner B. Overexpression of the c-erbB-2 protein in human breast tumor cell lines. J Cell Biochem 1989;39(2):167–73. 144. Bose S, Lesser ML, Norton L, Rosen PP. Immunophenotype of intraductal carcinoma. Arch Pathol Lab Med 1996;120(1):81-85. 145. Moreno A, Lloveras B, Figueras A, Escobedo A, Ramon JM, Sierra A, Fabra A. Ductal carcinoma in situ of the breast: correlation between histologic classifications and biologic markers. Mod Pathol 1997; 10(11):1088-1092. 146. Slamon DJ, Godolphin W, Jones LA. Studies of the HER2/neu proto-oncogene in human breast and ovarian cancer.Science 1989; 244(4905):707–712. 147. Mack L, Kerkvliet N, Doig G, O'Malley FP. Relationship of a new histological categorization of ductal carcinoma in situ of the breast with size and the immunohistochemical expression of p53, cerb B2, bcl-2, and ki-67. Hum Pathol 1997; 28(8):974-979. 148. Rosenthal SI, Depowski PL, Sheehan CE, Ross JS. Comparison of HER-2/neu oncogene amplification detected by fluorescence in situ hybridization in lobular and ductal breast cancer. Appl Immunohistochem Mol Morphol 2002; 10:40–46. 149. Barron JJ, Cziraky MJ, Weisman T, Hicks DG. HER-2 testing and subsequent trastuzumab treatment for breast cancer in a managed care environment. Oncologist 2009; 14(8):760-768. 150. Cuadros M, Villegas R. Systematic review of HER-2 breast cancer testing. Appl Immunohistochem Mol Morphol 2009;17(1):1-7. 151. Gong Y, Sweet W, Duh YJ, Greenfield L, Fang Y, Zhao J, Tarco E, Symmans WF, Isola J, Sneige N. Chromogenic in situ hybridization is a reliable method for detecting HER2 gene status in breast cancer: a multicenter study using conventional scoring criteria and the new ASCO/CAP recommendations. Am J Clin Pathol 2009;131(4):490-497. 152. Gong Y, Sweet W, Duh YJ, Greenfield L, Tarco E, Trivedi S, Symmans WF, Isola J, Sneige N. Performance of chromogenic in situ hybridization on testing HER2 Status in breast carcinomas with chromosome 17 polysomy and equivocal (2+) herceptest results: a study of two institutions using the conventional and new ASCO/CAP scoring criteria. Am J Clin Pathol 2009; 132(2):228-236. 153. Huston JS, George AJ. Engineered antibodies take center stage. Hum Antibodies 2001;10:127–142. 154. Clynes RA, Towers TL, Presta LG, Ravetch JV. Inhibitory Fc receptors modulates in vivo cytotoxicity against tumor targets. Nat Med 2000, 6:443-446. Medicinal Research Reviews 2012, 32(1), 166–215 155. Hudziak RM, Lewis GD, Winget M, Fendly BM, Shepard HM, Ullrich A: p185HER2 monoclonal antibody has antiproliferative effects in vitro and sensitizes human breast tumor cells to tumor necrosis factor. Mol Cell Biol 1989;9:1165-1172. 156. Nahta R, Esteva FJ: Herceptin: mechanisms of action and resistance. Cancer Lett 2006;232(2):123138. 157. Karamouzis MV, Konstantinopoulos PA, Papavassiliou AG. Trastuzumab--mechanism of action and use. N Engl J Med 2007;357(16):1664; author reply 1665-1666. 158. Barok M, Isola J, Palyi-Krekk Z, Nagy P, Juhasz I, Vereb G, Kauraniemi P, Kapanen A, Tanner M, Vereb G, Szollosi J. Trastuzumab causes antibody-dependent cellular cytotoxicity-mediated growth inhibition of submacroscopic JIMT-1 breast cancer xenografts despite intrinsic drug resistance. Mol Cancer Ther 2007;6(7):2065-2072. 159. Sliwkowski MX, Lofgren JA, Lewis GD, Hotaling TE, Fendly BM, Fox JA. Nonclinical studies addressing the mechanism of action of trastuzumab (Herceptin). Semin Oncol 1999;26(4) Suppl 12:60-70. 160. Emens LA, Davidson NE. Trastuzumab in breast cancer. Oncology (Williston Park) 2004; 18(9):1117-1128; discussion 1131-1112, 1137-1118. 161. Bartsch R, Wenzel C, Steger GG. Trastuzumab in the management of early and advanced stage breast cancer. Biologics 2007;1(1):19-31. 162. Hudis CA. Trastuzumab--mechanism of action and use in clinical practice. N Engl J Med 2007;357(1):39-51. 163. Mir O, Berveiller P, Pons G. Trastuzumab--mechanism of action and use. N Engl J Med 2007; 357(16):1664-1665; author reply 1665-1666. 164. Baselga J, Tripathy D, Mendelsohn J, Baughman S, Benz CC, Dantis L, Sklarin NT, Seidman AD, Hudis CA, Moore J. Phase II study of weekly intravenous trastuzumab (Herceptin) in patients with HER2/neu-overexpressing metastatic breast cancer. Semin Oncol 1999; 26:78-83. 165. Cobleigh MA, Vogel CL, Tripathy D, Robert NJ, Scholl S, Fehrenbacher L, Wolter JM, Paton V, Shak S, Lieberman G, Slamon DJ. Multinational study of the efficacy and safety of humanized antiHER2 monoclonal antibody in women who have HER2-overexpressing metastatic breast cancer that has progressed after chemotherapy for metastatic disease. J Clin Oncol 1999; 17(9):2639-2648. 166. Baselga J, Carbonell X, Casta˜neda-Soto NJ. Phase II study of efficacy, safety, and pharmacokinetics of trastuzumab monotherapy administered on a 3-weekly schedule.J Clin Oncol 2005; 23(10):2162–2171. 167. Vogel CL, Cobleigh MA, Tripathy D, Gutheil JC, Harris LN, Fehrenbacher L, Slamon DJ, Murphy M, Novotny WF, Burchmore M, Shak S, Stewart SJ, Press M. Efficacy and safety of trastuzumab as a single agent in first-line treatment of HER2-overexpressing metastatic breast cancer. J Clin Oncol 2002; 20(3):719-726. 168. Slamon DJ, Leyland-Jones B, Shak S, Fuchs H, Paton V, Bejamonde A, Fleming T, Eiermann W, Wolter J, Pegram M, Beselga J, Norton L. Use of chemotherapy plus a monoclonal antibody against HER2 for metastatic breast cancer that overexpress HER2. N Engl J Med 2001; 344(11):783-792. 169. Burstein HJ, Kuter I, Campos SM, Gelman RS, Tribou L, Parker LM, Manola J, Younger J, Matulouis U, Bunnell CA, Partridge AH, Richardson PG, Clarke K, Shulman LN, Winer EP. Clinical activity of trastuzumab and vinorelbine in women with HER2-overexpressing metastatic breast cancer. J Clin Oncol 2001; 19(10):2722-2730. 170. Marty M, Cognetti F, Maraninchi D, Snyder R, Mauriac L, Tubiana-Hulin M, Chan S, Grimes D, Anton A, Lluch A. Randomized phase II trial of the efficacy and safety of trastuzumab combined with docetaxel in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer administered as first-line treatment: the M77001 study group. J Clin Oncol 2005; 23:42654274. 171. Gasparini G, Gion M, Mariani L, Papaldo P, Crivellari D, Filippelli G, Morabito A, Silingardi V, Torino F, Spada A. Randomized Phase II Trial of weekly paclitaxel alone versus trastuzumab plus Medicinal Research Reviews 2012, 32(1), 166–215 weekly paclitaxel as first-line therapy of patients with positive advanced breast cancer. Breast Cancer Res Treat 2007; 101:355-365. 172. Petrelli F, Cabiddu M, Cazzaniga ME, Cremonesi M, Barni S. Targeted therapies for the treatment of breast cancer in the post-trastuzumab era. Oncologist 2008; 13(4):373-381. 173. Burstein HJ, Kuter I, Campos SM, Gelman RS, Tribou L, Parker LM, Manola J, Younger J, Matulonis U, Bunnell CA. Clinical activity of trastuzumab and vinorelbine in women with HER2overexpressing metastatic breast cancer. J Clin Oncol 2001; 19:2722-2730. 174. Burstein HJ, Harris LN, Marcom PK, Lambert-Falls R, Havlin K, Overmoyer B, Friedlander RJ, Jr., Gargiulo J, Strenger R, Vogel CL, Ryan PD, Ellis MJ, Nunes RA, Bunnell CA, Campos SM, Hallor M, Gelman R, Winer EP. Trastuzumab and vinorelbine as first-line therapy for HER2-overexpressing metastatic breast cancer: multicenter phase II trial with clinical outcomes, analysis of serum tumor markers as predictive factors, and cardiac surveillance algorithm. J Clin Oncol 2003; 21(15):28892895. 175. Papaldo P, Fabi A, Ferretti G, Mottolese M, Cianciulli AM, Di Cocco B, Pino MS, Carlini P, Di Cosimo S, Sacchi I. A phase II study on metastatic breast cancer patients treated with weekly vinorelbine with or without trastuzumab according to HER2 expression: changing the natural history of HER2-positive disease. Ann Oncol 2006; 17:630-636. 176. De Maio E, Pacilio C, Gravina A, Morabito A, Di Rella F, Labonia V, Landi G, Nuzzo F, Rossi E, Silvestro P. Vinorelbine plus 3-weekly trastuzumab in metastatic breast cancer: a singlecentre phase 2 trial. BMC Cancer 2007; 7 :50. 177. Burris H, 3rd, Yardley D, Jones S, Houston G, Broome C, Thompson D, Greco FA, White M, Hainsworth J. Phase II trial of trastuzumab followed by weekly paclitaxel/carboplatin as firstline treatment for patients with metastatic breast cancer. J Clin Oncol 2004; 22:1621-1629. 178. Robert N, Leyland-Jones B, Asmar L, Belt R, Ilegbodu D, Loesch D, Raju R, Valentine E, Sayre R, Cobleigh M. Randomized phase III study of trastuzumab, paclitaxel, and carboplatin compared with trastuzumab and paclitaxel in women with -overexpressing metastatic breast cancer. J Clin Oncol 2006; 24:2786-2792. 179. Fujimoto-Ouchi K, Sekiguchi F, Kazushige M. Preclinical study of continuous administration of trastuzumab as combination therapy after disease progression with trastuzumab monotherapy. Proc Am Assoc Cancer Res 2005; 46:[Abstr 5062]. 180. Fountzilas G, Razis E, Tsavdaridis D, Karina M, Labropoulos S, Christodoulou C, Mavroudis D, Gogas H, Georgoulias V, Skarlos D. Continuation of trastuzumab beyond disease progression is feasible and safe in patients with metastatic breast cancer: a retrospective analysis of 80 cases by the hellenic cooperative oncology group. Clin Breast Cancer 2003; 4:120-125. 181. Gelmon KA, Mackey J, Verma S, Gertler SZ, Bangemann N, Klimo P, Schneeweiss A, Bremer Soulieres D, Tonkin K. Use of trastuzumab beyond disease progression: observations from a retrospective review of case histories. Clin Breast Cancer 2004; 5:52-58. 182. Tripathy D, Slamon DJ, Cobleigh M, Arnold A, Saleh M, Mortimer JE, Murphy M, Stewart SJ. Safety of treatment of metastatic breast cancer with trastuzumab beyond disease progression. J Clin Oncol 2005; 22:1063-1070. 183. Bartsch R, Wenzel C, Hussian D, Pluschnig U, Sevelda U, Koestler W, Altorjai G, Locker GJ, Mader R, Zielinski CC. Analysis of trastuzumab and chemotherapy in advanced breast cancer after the failure of at least one earlier combination: an observational study. BMC Cancer 2006; 6:63. 184. Montemurro F, Donadio M, Clavarezza M, Redana S, Jacomuzzi ME, Valabrega G, Danese S, Vietti-Ramus G, Durando A, Venturini M. Outcome of patients with HER2-positive advanced breast cancer progressing during trastuzumab-based therapy. Oncologist 2006; 11:318-324. 185. Bartsch R, Wenzel C, Gampenrieder SP, Pluschnig U, Altorjai G, Rudas M, Mader RM, Dubsky P, Rottenfusser A, Gnant M, Zielinski, CC, Steger, GG. Trastuzumab and gemcitabine as salvage therapy in heavily pre-treated patients with metastatic breast cancer. Cancer Chemother Pharmacol. 2008;62(5):903-910. Medicinal Research Reviews 2012, 32(1), 166–215 186. O'Shaughnessy J, Blackwell KL, Burstein H, Storniolo AM, Sledge G, Baselga J, Koehler M, Laabs S, Florance A, Roychowdhury D. A randomized study of lapatinib alone or in combination with trastuzumab in heavily pretreated HER2+ metastatic breast cancer progressing on trastuzumab therapy. J Clin Oncol (Meeting Abstract) 2008; 26:1015. 187. von Minckwitz G, du Bois A, Schmidt M, Maass N, Cufer T, de Jongh FE, Maartense E, Zielinski C, Kaufmann M, Bauer W. Trastuzumab beyond progression in human epidermal growth factor receptor 2-positive advanced breast cancer: a german breast group 26/breast international group 0305 study. J Clin Oncol 2009; 27:1999-2006. 188. Park IH, Ro J, Lee KS, Nam BH, Kwon Y, Shin KH. Trastuzumab treatment beyond brain progression in HER2-positive metastatic breast cancer. Ann Oncol 2009; 20(1):56-62. 189. Spielmann M, Roché H, Humblet Y, Delozier T, Bourgeois H, Serin D, Romieu G, Canon JL, Monnier A, Piot G. 3-year follow-up of trastuzumab following adjuvant chemotherapy in node positive HER2-positive breast cancer patients: results of the PACS-04 trial. San Antonio Breast Cancer Symposium 2007;[abstr 72]. 190. Baselga J, Perez EA, Pienkowski T, Bell R. Adjuvant Trastuzumab: A Milestone in the Treatment of -Positive Early Breast Cancer. The Oncologist 2006;11(suppl 1):4–12 191. Dahabreh IJ, Linardou H, Siannis F, Fountzilas G, Murray S. Trastuzumab in the adjuvant treatment of early-stage breast cancer: a systematic review and meta-analysis of randomized controlled trials. Oncologist 2008; 13(6):620-630. 192. Romond EH, Perez EA, Bryant J, Suman VJ, Geyer CE, Jr., Davidson NE, Tan-Chiu E, Martino S, Paik S, Kaufman PA. Trastuzumab plus adjuvant chemotherapy for operable HER2-positive breast cancer. N Engl J Med 2005; 353:1673-1684. 193. Perez EA, Suman VJ, Davidson N. NCCTG N9831. May 2005 update. Slide presentation at the 41st American Society of Clinical Oncology Annual Meeting, Orlando, Florida, May 13–17, 2005. Available at http://www.asco.org/ac/1,1003,_12-002511-00_18-0034-00_19-005815-00_21001,00.asp. Accessed June 7, 2006. 194. Piccart-Gebhart MJ, Procter M, Leyland-Jones B, Goldhirsch A, Untch M, Smith I, Gianni L, Baselga J, Bell R, Jackisch C. Trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer. N Engl J Med 2005; 353:1659–72. 195. Slamon D, Eiermann W, Robert N, Pienkowski T, Martin M, Pawlicki M, Chan A, Smylie M, Liu M, Falkson C. BCIRG 006: 2nd interim analysis phase III randomized trial comparing doxorubicin and cyclophosphamide followed by docetaxel (AC→T) with doxorubicin and cyclophosphamide followed by docetaxel and trastuzumab (AC→TH) with docetaxel, carboplatin and trastuzumab (TCH) in Her2neu positive early breast cancer patients. San Antonio Breast Cancer Symposium 2006; [Abstr 52]. 196. Joensuu H, Kellokumpu-Lehtinen PL, Bono P, Alanko T, Kataja V, Asola R, Utriainen T, Kokko R, Hemminki A, Tarkkanen M. Adjuvant docetaxel or vinorelbine with or without trastuzumab for breast cancer. N Engl J Med 2006; 354:809-820. 197. Price-Schiavi SA, Jepson S, Li P, Arango M, Rudland PS, Yee L,Carraway KL. Rat Muc4 (sialomucin complex) reduces binding of anti-ErbB2 antibodies to tumor cell surfaces, a potential mechanism for herceptin resistance. Int J Cancer 2002, 99:783-791. 198. Nagy P, Friedlander E, Tanner M, Kapanen AI, Carraway KL, Isola J, Jovin TM. Decreased accessibility and lack of activation of ErbB2 in JIMT-1, a herceptin-resistant, MUC4-expressing breast cancer cell line. Cancer Res 2005, 65:473-482. 199. Lu Y, Zi X, Zhao Y, Mascarenhas D, Pollak M. Insulin-like growth factor-I receptor signaling and resistance to trastuzumab (Herceptin). J Natl Cancer Inst 2001; 93:1852-1857. 200. Nahta R, Yuan LX, Zhang B, Kobayashi R, Esteva FJ. Insulin-like growth factor-I receptor/human epidermal growth factor receptor 2 heterodimerization contributes to trastuzumab resistance of breast cancer cells. Cancer Res 2005; 65:11118-11128. Medicinal Research Reviews 2012, 32(1), 166–215 201. Agus DB, Akita RW, Fox WD, Lewis GD, Higgins B, Pisacane PI, Lofgren JA, Tindell C, Evans DP, Maiese K. Targeting ligand-activated ErbB2 signaling inhibits breast and prostate tumor growth. Cancer Cell 2002; 2:127-137. 202. Motoyama AB, Hynes NE, Lane HA: The efficacy of ErbB receptor- targeted anticancer therapeutics is influenced by the availability of epidermal growth factor-related peptides. Cancer Res 2002; 62:3151-3158. 203. Nagata Y, Lan KH, Zhou X, Tan M, Esteva FJ, Sahin AA, Klos KS, Li P, Monia BP, Nguyen NT, Hortobagyi GN, Hung MC, Yu D. PTEN activation contributes to tumor inhibition by trastuzumab, and loss of PTEN predicts trastuzumab resistance in patients. Cancer Cell 2004;6(2):117-127. 204. Saez R, Molina MA, Ramsey EE, Rojo F, Keenan EJ, Albanell J, Lluch A, Garcia-Conde J, Baselga J, Clinton GM. p95 predicts worse outcome in patients with HER-2-positive breast cancer. Clin Cancer Res 2006; 12(2):424-431. 205. Colomer R, Montero S, Lluch A, Ojeda B, Barnadas A, Casado A, Massuti B, Cortes-Funes H, Lloveras B. Circulating HER-2 extracellular domain and resistance to chemotherapy in advanced breast cancer. Clin Cancer Res 2000; 6:2356-2362. 206. Leitzel K, Teramoto Y, Konrad K, Chinchilli VM, Volas G, Grossberg H, Harvey H, Demers L, Lipton A. Elevated serum c-erbB-2 antigen levels and decreased response to hormone therapy of breast cancer. J Clin Oncol 1995; 13:1129-1135. 207. Yamauchi H, O’Neill A, Gelman R, Carney W, Tenney DY, Hosch S, Hayes DF. Prediction of response to antiestrogen therapy in advanced breast cancer patients by pretreatment circulating levels of extracellular domain of the HER-2/c-neu protein. J Clin Oncol 1997; 15:2518-2525. 208. Hayes DF, Yamauchi H, Broadwater G, Cirrincione CT, Rodrigue SP, Berry DA, Younger J, Panasci LL, Millard F, Duggan DB. Cancer and Leukemia Group B: Circulating HER-2/erbB-2/c-neu (HER2) extracellular domain as a prognostic factor in patients with metastatic breast cancer: Cancer and Leukemia Group B Study 8662. Clin Cancer Res 2001; 7:2703-2711. 209. Christianson TA, Doherty JK, Lin YJ, Ramsey EE, Holmes R, Keenan EJ, Clinton GM. NH2terminally truncated HER-2/neu protein: relationship with shedding of the extracellular domain and with prognostic factors in breast cancer. Cancer Res 1998; 58:5123-5129. 210. Molina MA, Saez R, Ramsey EE, Garcia-Barchino MJ, Rojo F, Evans AJ, Albanell J, Keenan EJ, Lluch A, Garcia-Conde J. NH2-terminal truncated HER-2 protein but not full-length receptor is associated with nodal metastasis in human breast cancer. Clin Cancer Res 2002; 8:347-353. 211. Molina MA, Codony-Servat J, Albanell J, Rojo F, Arribas J, Baselga J. Trastuzumab (Herceptin), a humanized anti-HER2 receptor monoclonal antibody, inhibits basal and activated HER2 ectodomain cleavage in breast cancer cells. Cancer Res 2001; 61:4744-4749. 212. Esteva FJ, Cheli C, Fritsche HA, Fornier M, Slamon DJ, Thiel RP, Luftner D, Ghani F. Clinical utility of circulating HER-2/neu in monitoring and prediction of progression-free survival in metastatic breast cancer patients undergoing trastuzumabbased therapy. Breast Can Res Treat 2004; 88:6001. 213. Kostler WJ, Schwab B, Singer CF, Neumann R, Rucklinger E, Brodowicz T, Tomek S, Niedermayr M, Hejna M, Steger GG. Monitoring of serum HER-2/neu predicts response and progression-free survival to trastuzumab-based treatment in patients with metastatic breast cancer. Clin Cancer Res 2004; 10:1618-1624. 214. Fornier MN, Seidman AD, Schwartz MK, Ghani F, Thiel R, Norton L, Hudis C: Serum HER-2 extracellular domain in metastatic breast cancer patients treated with weekly trastuzumab and paclitaxel: association with HER2 status by immunohistochemistry and fluorescence in situ hybridization and with response rate. Ann Oncol 2005; 16:234-239. 215. Nahta R, Esteva FJ. HER-2 therapy: molecular mechanisms of trastuzumab resistance. Breast Cancer Res 2006; 8(6):215. Medicinal Research Reviews 2012, 32(1), 166–215 216. Le XF, Claret FX, Lammayot A, Tian L, Deshpande D, LaPushin R, Tari AM, Bast RC Jr. The role of cyclin-dependent kinase inhibitor p27Kip1 in anti-HER2 antibody-induced G1 cell cycle arrest and tumor growth inhibition. J Biol Chem 2003; 278:23441-23450. 217. Nahta R, Takahashi T, Ueno NT, Hung MC, Esteva FJ: P27 (kip1) down-regulation is associated with trastuzumab resistance in breast cancer cells. Cancer Res 2004, 64:3981-3986. 218. Adams CW, Allison DE, Flagella K, Presta L, Clarke J, Dybdal N, McKeever K, Sliwkowski MX. Humanization of a recombinant monoclonal antibody to produce a therapeutic HER dimerization inhibitor, pertuzumab. Cancer Immunol Immunother 2006; 55(6):717-727. 219. Franklin MC, Carey KD, Vajdos FF, Leahy DJ, de Vos AM, Sliwkowski MX. Insights into ErbB signaling from the structure of the ErbB2-pertuzumab complex. Cancer Cell 2004; 5:317–28. 220. Fendly BM, Winget M, Hudziak RM, Lipari MT, Napier MA, Ullrich A. Characterization of murine monoclonal antibodies reactive to either the human epidermal growth factor receptor or HER-2/neu gene product. Cancer Res 1990; 50:1550–8. 221. Agus DB, Gordon MS, Taylor C, Natale RB, Karlan B, Mendelson DS, Press MF, Allison DE, Sliwkowski MX, Lieberman G, Kelsey SM, Fyfe G. Phase I clinical study of pertuzumab, a novel HER dimerization inhibitor, in patients with advanced cancer. J Clin Oncol 2005; 23(11):2534-2543. 222. Yamamoto N, Yamada Y, Fujiwara Y, Yamada K, Fujisaka Y, Shimizu T, Tamura T. Phase I and Pharmacokinetic Study of HER2-targeted rhuMAb 2C4 (Pertuzumab, RO4368451) in Japanese Patients with Solid Tumors. Jpn J Clin Oncol 2009; 39(4)260–266. 223. Cortes L, Baselga J, Kellokumpu-Lehtinen P, Bianchi G, Cameron D, Miles D, Salvagni S, Wardley A, Goeminne JC, Gianni L. Open label, randomized, phase II study of pertuzumab in patients with metastatic breast cancer with low expression of HER-2. J Clin Oncol 2005; 23 suppl 16:[abstract 3068]. 224. Gelmon KA, Fumoleau P, Verma S, Wardley AM, Conte PF, Miles d, Giani L, McNally VA, Ross G, Baselga J. Results of a phase II trial of trastuzumab (H) and pertuzumab (P) in patients (pts) with HER2-positive metastatic breast cancer (MBC) who had progressed during trastuzumab therapy. J Clin Oncol 2008; 26 suppl 15:[abstract 1026]. 225. A Study to evaluate Pertuzumab + Trastuzumab + Docetaxel Vs. Placebo + Trastuzumab + Docetaxel in previously untreated Her2-positive Metastatic Breast Cancer (CLEOPATRA)NCT00567190 [Roche]. www.pressportal.de. 226. Mendelsohn J. Epidermal growth factor receptor inhibition by a monoclonal antibody as anticancer therapy. Clin Cancer Res 1997; 3(12 pt 2):2703–2707. 227. Thomas SM, Grandis JR. Pharmacokinetic and pharmacodynamic properties of EGFR inhibitors under clinical investigation. Cancer Treat Rev 2004; 30(3):255-268. 228. Masui H, Kawamoto T, Sato JD, Wolf B, Sato G, Mendelsohn J. Growth inhibition of human tumor cells in athymic mice by anti-epidermal growth factor receptor monoclonal antibodies. Cancer Res 1984; 44:1002–1007. 229. Ciardiello F, Tortora G. EGFR antagonists in cancer treatment. N Engl J Med 2008; 358:1160-1174. 230. Fan Z, Lu Y, Wu X, Mendelsohn J. Antibody-induced epidermal growth factor receptor dimerization mediates inhibition of autocrine proliferation of A431 squamous carcinoma cells. J Biol Chem 1994;269:27595–27602. 231. Wu X, Rubin M, Fan Z, DeBlasio T, Soos T, Koff A, Mendelsohn J. Involvement of p27 KIP1 in G1 arrest mediated by an anti-epidermal growth factor receptor monoclonal antibody. Oncogene 1996;12:1397–1403. 232. Kawamoto T, Sato JD, Le A, Polikoff J, Sato GH, Mendelsohn J. Growth stimulation of A431 cells by EGF: identification of high affinity receptors for epidermal growth factor by an anti-receptor monoclonal antibody. Proc Natl Acad Sci U S A 1983; 80(5):1337–1341. 233. Gill GN, Kawamoto T, Cochet C, Le A, Sato JD, Masui H, MacLeod C, Mendelsohn J. Monoclonal anti-epidermal growth factor receptor antibodies which are inhibitors of epidermal growth factor Medicinal Research Reviews 2012, 32(1), 166–215 binding and antagonists of epidermal growth factor-stimulated tyrosine protein kinase activity. J Biol Chem 1984; 259:7755–7760. 234. Goldstein NI, Prewett M, Zuklys K, Rockwell P, Mendelsohn J. Biological efficacy of a chimeric antibody to the epidermal growth factor receptor in a human tumor xenograft model. Clin Can Res 1995; 1:1311–1318. 235. Petit AM, Rak J, Hung MC, Rockwell P, Goldstein N, Fendly B, Kerbel RS. Neutralizing antibodies against epidermal growth factor and ErbB-2/neu receptor tyrosine kinases down-regulate vascular endothelial growth factor production by tumor cells in vitro and in vivo: angiogenic implications for signal transduction therapy of solid tumors. Am J Pathol 1997;151(6):1523–1530 236. Perrotte P, Matsumoto T, Inoue K, Kuniyasu H, Eve BY, Hicklin DJ, Radinsky R, Dinney CP. 1999 Anti-epidermal growth factor receptor antibody C225 inhibits angiogenesis in human transitional cell carcinoma growing orthotopically in nude mice. Clin Cancer Res 1999; 5(2):257–265. 237. Normanno N, Bianco C, De Luca A, Maiello MR, Salomon DS. Target-based agents against ErbB receptors and their ligands: a novel approach to cancer treatment. Endo Rel Can 2003; 10: 1-21. 238. Modi S, D'Andrea G, Norton L, Yao TJ, Caravelli J, Rosen PP, Hudis C, Seidman AD. A phase I study of cetuximab/paclitaxel in patients with advanced-stage breast cancer. Clin Breast Cancer 2006; 7(3):270-277. 239. O’Shaughnessy J, Weckstein DJ, Vukelja SJ, Melyntyre K, Krebow L, Holmes FA Preliminary results of rarandomized phase II study of weekly irinotecan/carboplatin with or without cetuximab in patients with metastatic breast cancer. Breast Cancer Res Treat 2007;106(suppl 1):[abstract S32]. 240. Carey L, Rugo HS, Marcom P, Irvin W, Ferraro M, Burrows E, He X, Perou CM, Winer EP. TBCRC 001: EGFR inhibition with cetuximab added to carboplatin in metastatic triple negative (basal-like) breast cancer. J Clin Oncol 2008; 26 suppl 15:[abstract 1009]. 241. Hobday T, Stella P, Fitch T, Jaslowski A, LaPlant B, Ames MM, Goetz MP, Perez EA. N0436: A phase II trial of irinotecan plus cetuximab in patients with metastatic breast cancer and prior anthracycline and/or taxane-containing therapy. J Clin Oncol 2008; 26 suppl 15:[abstract 1081]. 242. Spector N, Xia W, El-Hariry I, Yarden Y, Bacus S. Small molecule tyrosine kinase inhibitors. Breast Cancer Res 2007; 9(2):204-210. 243. Allen LF, Lenehan PF, Eiseman IA, Elliott WL, Fry DW. Potential benefits of the irreversible panerbB inhibitor, CI-1033, in the treatment of breast cancer. Semin Oncol 2002; 11:11-21. 244. Xia W, Liu L-H, Ho P, Spector NL. Truncated ErbB2 receptor (p95ErbB2) is regulated by heregulin through heterodimer formation with ErbB3 yet remains sensitive to the dual EGFR/ErbB2 kinase inhibitor GW572016. Oncogene 2004, 23:646-653. 245. Walter HJ Ward, PNC, Slater AM, Huw Davies D, Holdgate GA, Leslie R. Epidermal growth factor receptor tyrosine kinase investigation of catalytic mechanism, structure based searching and discovery of a potent inhibitor Biochem Pharmacol 1994; 48:659–666. 246. Wakeling AE, Guy SP, Woodburn JR, Ashton SE, Curry BJ, Barker AJ, Gibson KH. ZD1839 (Iressa): an orally active inhibitor of epidermal growth factor signaling with potential for cancer therapy. Cancer Res 2002; 62(20):5749–54. 247. Sirotnak FM, Zakowski MF, Miller VA, Scher HI, Kris MG. Efficacy of cytotoxic agents against human tumour xenografts is markedly enhanced by coadministration of ZD1839 (Iressa), an inhibitor of EGFR tyrosine kinase. Clin Cancer Res 2000; 6:4885–92. 248. Moasser MM, Basso A, Averbuch SD, Rosen N. The tyrosine kinase inhibitor ZD1839 (Iressa) inhibits HER2-driven signaling and suppresses the growth of HER2-overexpressingtumour cells. Cancer Res 2001; 61:7184–8. 249. Moulder SL, Yakes Fm, Muthuswamy SK, Bianco R, Sampson JF, Arteaga CL. Epidermal growth factor receptor (HER-1) tyrosine kinase inhibitor ZD1839 (Iressa) inhibits HER2/Neu (ErbB2) overexpressing breast cancer cells invitro and invivo. Cancer Res 2001;61:8887-8895. Medicinal Research Reviews 2012, 32(1), 166–215 250. Basso A, Averbach SD, Rosen N, Moasser MM. Inhibition of PI3 kinase/ Akt pathway mediates antitumour effects of ZD1839 (Iressa) in HER2-overexpressing tumours. Proc Am Soc Clin Oncol, Abstract #1662; 2002. 251. Ciardiello F, Caputo R, Bianco R, Damiano V, Pomatico G, De Placido S, Bianco AR, Tortora G. Antitumour effect and potentiation of cytotoxic drugs activity in human cancer cells by ZD-1839 (Iressa), an epidermal growth factor receptor-selective tyrosine kinase inhibitor. Clin Cancer Res 2000; 6:2053–63. 252. Huang SM, Li J, Harari PM. Modulation of radiation response and tumour-induced angiogenesis following EGFR blockade by ZD1839 (Iressa) in human squamous cell carcinoma. Proc Am Soc Clin Oncol 2001;[abstr #259] 253. Ciardiello F, Caputo R, Bianco R, Damiano V, Fontanini G, Cuccato S, De Placido S, Bianco AR, Tortora G. Inhibition of growth factor production and angiogenesis in human cancer cells by ZD1839 (Iressa), a selective epidermal growth factor receptor tyrosine kinase inhibitor. Clin Cancer Res 2001; 7:1459–65. 254. Miller VA, DJ, Heelan RT, Pizzo BA, Perez WJ, Bass A, Kris MG, Ochs J, Averbuch S, Pilot A. Trial demonstrates the safety of ZD1839 (‘Iressa’, an oral epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), in combination with carboplatin (C) and paclitaxel (P) in previously untreated advanced non-small cell lung cancer (NSCLC). Proc Am Soc Clin Oncol 2001;abstr . 255. Baselga J, Albanell J, Ruiz A, Lluch A, Gascon P, Guillem V, Gonzalez S, Sauleda S, Marimon I, Tabernero JM, Koehler MT, Rojo F. Phase II and tumor pharmacodynamic study of Gefitinib in patients with advanced breast cancer. J Clin Oncol 2005; 23(23):5323-5333. 256. Von Minckwitz G, Jonat W, Fasching P, du Bois A, Kleeberg U, Luck HJ, Kettner E, Hilfrich J, Eiermann W, Torode J, Schneeweiss A. A multicentre phase II study on Gefitinib in taxane- and anthracycline-pretreated metastatic breast cancer. Breast Cancer Res Treat 2005; 89(2):165-172 257. Ciardiello F, Troiani T, Caputo F, De Laurentiis M, Tortora G, Palmieri G, De Vita F, Diadema MR, Orditura M, Colantuoni G, Gridelli C, Catalano G, De Placido S, Bianco AR. Phase II study of Gefitinib in combination with docetaxel as first-line therapy in metastatic breast cancer. Br J Cancer 2006; 94(11):1604-1609. 258. Dennison SK, Jacobs SA, Wilson JW, Seeger J, Cescon TP, Raymond JM, Geyer CE, Wolmark N, Swain SM. A phase II clinical trial of ZD1839 (Iressa) in combination with docetaxel as first-line treatment in patients with advanced breast cancer. Invest New Drugs 2007; 25(6):545-551. 259. Buzdar A. Anastrozole as adjuvant therapy for early-stage breast cancer: implications of the ATAC trial. Clin Breast Cancer 2003;4 Suppl 1:S42-48. 260. Buzdar AU. 'Arimidex' (anastrozole) versus tamoxifen as adjuvant therapy in postmenopausal women with early breast cancer--efficacy overview. J Steroid Biochem Mol Biol 2003;86(3-5):399403. 261. Polychronis A, Sinnett HD, Hadjiminas D, Singhal H, Mansi JL, Shivapatham D, Shousha S, Jiang J, Peston D, Barrett N, Vigushin D, Morrison K, Beresford E, Ali S, Slade MJ, Coombes RC. Preoperative Gefitinib versus Gefitinib and anastrozole in postmenopausal patients with oestrogenreceptor positive and epidermal-growth-factor-receptor-positive primary breast cancer: a doubleblind placebo-controlled phase II randomised trial. Lancet Oncol 2005; 6(6):383-391. 262. Cristofanilli M, Valero V, Mangalik A, Rabinowitz I, Arena FP, Kroener JF, Curcio E, Watkins C, Magill P. A phase II multicenter, double blind, randomized trial to compare anastrozole plus Gefitinib with anastrazole plus placebo in postmenopausal women with hormone receptor positive metastatic breast cancer. J Clin Oncol 2008;26 suppl 15:[abstract 1012]. 263. Raymond E, Faivre S, Armand JP. Epidermal growth factor receptor tyrosine kinase as a target for anticancer therapy. Drugs 2000; 60 Suppl 1:15-23; discussion 41-12. 264. Bulgaru AM, Mani S, Goel S, Perez-Soler R. Erlotinib (Tarceva): a promising drug targeting epidermal growth factor receptor tyrosine kinase. Expert Rev Anticancer Ther 2003; 3(3):269-279. Medicinal Research Reviews 2012, 32(1), 166–215 265. Britten CD. Targeting ErbB receptor signaling: a pan-ErbB approach to cancer. Mol Cancer Ther 2004; 3 10):1335-1342 266. Dickler MN, Rugo HS, Eberle CA, Brogi E, Caravelli JF, Panageas KS, Boyd J, Yeh B, Lake DE, Dang CT, Gilewski TA, Bromberg JF, Seidman AD, D'Andrea GM, Moasser MM, Melisko M, Park JW, Dancey J, Norton L, Hudis CA. A phase II trial of Erlotinib in combination with bevacizumab in patients with metastatic breast cancer. Clin Cancer Res 2008; 14 (23):7878-7883. 267. Kaur H, Silverman P, Singh D, Cooper BW, Fu P, Krishnamurthi S, Remick S, Overmoyer B.Toxicity and outcome data in a phase II study of weekly docetaxel in combination with Erlotinib in recurrent and/or metastatic breast cancer (MBC). J Clin Oncol 2006; 24 suppl 18:10623. 268. Gaul MD, Guo Y, Affleck K, Cockerill GS, Gilmer TM, Griffin RJ, Guntrip S, Keith BR, Knight WB, Mullin RJ, Murray DM, Rusnak DW, Smith K, Tadepalli S, Wood ER, Lackey K. Discovery and biological evaluation of potent dual ErbB-2/EGFR tyrosine kinase inhibitors: 6thiazolylquinazolines. Bioorg Med Chem Lett 2003; 13 (4):637-640. 269. Rusnak DW, Affleck K, Cockerill SG, Stubberfield C, Harris R, Page M, Smith KJ, Guntrip SB,Carter MC, Shaw RJ. The characterization of novel, dual ErbB-2/EGFR, tyrosine kinase inhibitors: potential therapy for cancer. Cancer Res 2001; 61:7196-7203. 270. Rusnak DW, Lackey K, Affleck K, Wood ER, Alligood KJ, Rhodes N, Keith BR, Murray DM, Glennon K, Knight WB, Mullin RJ, Gilmer TM. The Effects of the Novel, Reversible Epidermal Growth Factor Receptor/ErbB-2 Tyrosine Kinase Inhibitor, GW2016, on the Growth of Human Normal and Tumor-derived Cell Lines in Vitro and in Vivo. Mol Cancer Ther 2001;1(2):85-94. 271. Scaltriti M, Rojo F, Ocana A, Anido J, Guzman M, Cortes J, Di Cosimo S, Matias-Guiu X, Ramony Cajal S, Arribas J. Expression of p95HER2, a truncated form of the HER2 receptor,and response to anti-HER2 therapies in breast cancer. J Natl Cancer Inst 2007; 99 :628-638. 272. Burstein HJ, Storniolo AM, Franco S, Forster J, Stein S, Rubin S, Salazar VM, Blackwell KL. A phase II study of lapatinib monotherapy in chemotherapy-refractory HER2-positive and HER2negative advanced or metastatic breast cancer. Ann Oncol 2008; 19(6):1068-1074. 273. Burris HA, 3rd, Hurwitz HI, Dees EC, Dowlati A, Blackwell KL, O'Neil B, Marcom PK, Ellis MJ, Overmoyer B, Jones SF, Harris JL, Smith DA, Koch KM, Stead A, Mangum S, Spector NL. Phase I safety, pharmacokinetics, and clinical activity study of lapatinib (GW572016), a reversible dual inhibitor of epidermal growth factor receptor tyrosine kinases, in heavily pretreated patients with metastatic carcinomas. J Clin Oncol 2005; 23(23):5305-5313. 274. Dees EC, Burris H, Hurwitz H, Dowlaty A, Smith D, Koch K, Stead A, Mangum S, Harris J, Spector N. Clinical Summary of 67 heavily pretreated patients with metastatic breast carcinomas treated with GW572016 in a phase Ib study. Proc Am Soc Clin Oncol 2004;23:241. 275. Blackwell K, Pegram MD, Tan-Chiu E, Schwartzberg LS, Arbushites MC, Maltzman JD, Forster JK, Rubin SD, Stein SH, Burstein HJ. Single- agent lapatinib for HER 2 overexpressing advanced or metstatic breast cancer that progressed on first- or second- line trastuzumab- containing regimens. Ann Oncol 2009; 20(6): 1026-1031. 276. Gomez H, Doval DC, Chavez MA, Ang PC, Aziz Z, Nag S, Ng C, Franco SX, Chow LW, Arbushites MC, Casey MA, Berger MS, Stein SH, Sledge GW,. Efficacy and safety of lapatinib as first line therapy for ErbB2-amplified locally advanced or metastatic breast cancer. J Clin Oncol 2008; 26(18): 2999-3005. 277. Spielmann M, Roche H, Delozier T, Canon JL, Romieu G, Burgeois H, Extra JM, Serin D, Kerbrat P, Mechiels JP, Lortholary A, Orfeuvre H, Campone M, Hardy-Bessarcl AC, Coudert B, Maerevoet M, Piot G, Karaman A, Martyn AL, Penault-Llorea F. Trastuzumab for patients with axillary-nodepositive breast cancer: results of FNCLCC- PACS 04 trial. J Clin Oncol 2009;27(36):6129-6134. 278. Gomez HL, Doval DC, Chavez MA. Efficacy and safety of lapatinib as first-line therapy for ErbB2amplified locally advanced or metastatic breast cancer. J Clin Oncol 2008; 26:2940–42. 279. Lin NU, Carey LA, Liu MC, Younger J, Come SE, Ewend M, Harris GJ, Bullitt E, Abbeele ADV, Henson JW, Li X, Gelman R, Burstein HJ, Kasparian E, Kirsch DG, Crawford A, Hochberg F, Winer Medicinal Research Reviews 2012, 32(1), 166–215 EP. Phase II Trial of Lapatinib for Brain Metastases in Patients With Human Epidermal Growth Factor Receptor 2–Positive. Breast Can Jr Clin Oncol 2008; 28(12):1993-1999 280. Johnston S, Trudeau M, Kaufman B, Boussen H, Blackwell K, Lo Russo P, Lombardi DP, Ben Ahmed S, Citri DL, De Silvio ML, Harris J, Westlund RE, Salazar V, Zaks TZ, Spector NL. Phase II study of predictive biomarker profiles for response targeting human epidermal growth factor receptor 2 (HER-2) in advanced inflammatory breast cancer with lapatinib monotherapy. J Clin Oncol 2008; 26(7): 1066-1072. 281. Kaufman B, Trudeau M, Awada A, Blackwell K, Bachelot T, Salazar V, DeSilvio M, Westlund R, Zaks T, Spector N, Johnston S. Lapatinib monotherapy in patients with HER2-overexpressing relapsed or refractory inflammatory breast cancer: final results and survival of the expanded HER2+ cohort in EGF103009, a phase II study. Lancet Oncol 2009; 10(6):581-588. 282. Kumar R, Knick VB, Rudolph SK, Johnson JH, Crosby RM, Crouthamel MC, Hopper TM, Miller CG, Harrington LE, Onori JA, Mullin RJ, Gilmer TM, Truesdale AT, Epperly AH, Boloor A, Stafford JA, Luttrell DK, Cheung M. Pharmacokinetic-pharmacodynamic correlation from mouse to human with pazopanib, a multikinase angiogenesis inhibitor with potent antitumor and antiangiogenic activity. Mol Cancer Ther 2007;6(7):2012-2021. 283. Slamon D, Gomez HL, Kabbinavar FF, Amit O, Richie M, Pandite L, Goodman V. Randomised study of pazopanib + lapatinib vs. lapatinib alone in patients with HER2-positive advanced or metastatic breast cancer . J Clin Oncol 2008; 26 Suppl 15:[abstact 1016]. 284. Rugo HS, Franco S, Munster P, Stopeck A, Ma W, Lyandres J, Lahiri S, Arbushites M, Koehler M, Dickler MN. A phase II evaluation of lapatinib (L) and bevacizumab (B) in HER2+ metastatic breast cancer (MBC). J Clin Oncol 2008; 26 Suppl 15:[abstract 1042]. 285. Miller K, Wang M, Gralow J, Dickler M, Cobleigh M, Perez EA, Shenkier T, Cella D, Davidson NE. Paclitaxel plus bevacizumab versus paclitaxel alone for metastatic breast cancer. N Engl J Med 2007; 357:2666-2676. 286. Miles D, Chan A, Romieu G, Dirix LY, Cortes J, Pivot X, Tomczak P, Taran T, Harbeck N, Steger GG. Randomized, double-blind, placebo-controlled, phase III study of bevacizumab with docetaxel or docetaxel with placebo as first-line therapy for patients with locally recurrent or metastatic breast cancer (MBC): AVADO. J Clin Oncol 2008;26: abstr LBA1011. 287. Blackwell KL, Burstein HJ, Storlinio Am, Rugo H, Sledge G, Kochler M, Ellis C, Casey m, Vukelja S, Bischoff J, Baselga J, O’Shaughnessy J. Randomised Study of Lapatinib alone or in Combination with Trastuzumab in Women with ErbB2 positive, Trastuzumab-Refractory Metastatic Breast Cancer. J Clin Oncol 2010 [In Press]. 288. Geyer CE, Forster J, Lindquist D, Chan S, Romieu CG, Pienkowski T, Jagiello-Gruszfeld A, Crown J, Chan A, Kaufman B, Skarlos D, Campone M, Davidson N, Berger M, Oliva C, Rubin SD, Stein S, Cameron D. Lapatinib plus capecitabine for HER2-positive advanced breast cancer. N Engl J Med 2006; 355(26):2733-2743. 289. Cameron D, Casey M, Press M, Lindquist D, Pienkowski T, Romieu CG, Chan S, Jagiello-Gruszfeld A, Kaufman B, Crown J, Chan A, Campone M, Viens P, Davidson N, Gorbounova V, Raats JI, Skarlos D, Newstat B, Roychowdhury D, Paoletti P, Oliva C, Rubin S, Stein S, Geyer CE. A phase III randomized comparison of lapatinib plus capecitabine versus capecitabine alone in women with advanced breast cancer that has progressed on trastuzumab: updated efficacy and biomarker analyses. Breast Cancer Res Treat 2008;112(3):533-543. 290. Di Leo A, Gomez HL, Aziz Z, Zvirbule Z, Bines J, Arbushites MC, Guerrera SF, Koehler M, Oliva C, Stein SH, Williams LS, Dering J, Finn RS, Press MF. Phase III, double-blind, randomized study comparing lapatinib plus paclitaxel with placebo plus paclitaxel as first-line treatment for metastatic breast cancer. J Clin Oncol 2008;26(34):5544-5552. 291. Xia W, Bacus S, Hegde P. A model of acquired autoresistance to a potent ErbB2 tyrosine kinase inhibitor and a therapeutic strategy to prevent its onset in breast cancer. Proc Natl Acad Sci U S A 2006; 103:7795–800. Medicinal Research Reviews 2012, 32(1), 166–215 292. Chu I, Blackwell K, Chen S, Slingerland J. The dual ErbB1/ErbB2 inhibitor, lapatinib (GW572016), cooperates with tamoxifen to inhibit both cell proliferation- and estrogen-dependent gene expression in antiestrogen-resistant breast cancer. Cancer Res 2005; 65:18–25. 293. Chowdhury S, Pickering LM, Ellis PA. Lapatinib: a novel dual tyrosine kinase inihibitor. Targ Oncol 2007; 2:107–12. 294. Li X, Lewis MT, Huang J, Gutierrez C, Osborne CK, Wu MF, Hilsenbeck SG, Pavlick A, Zhang X, Chamness GC. Intrinsic resistance of tumorigenic breast cancer cells to chemotherapy. J Natl Cancer Inst 2008; 100:672-679. 295. Gray JW, Das D, Wang N, Kuo W, Press MF, Di Leo A, Ellis C, Arbushites M, Williams L, Koehler M. Identification of a 6 gene molecular predictor of lapatinib related benefit: from breast cancer cell lines to a phase III trial. J Clin Oncol 2008; 26: 1043. 296. Allen LF, Lenehan PF, Eiseman IA, Elliott WL, Fry DW. Potential benefits of the irreversible panerbB inhibitor, CI-1033, in the treatment of breast cancer. Semin Oncol 2002;29(3) Suppl 11:11-21. 297. Slichenmyer WJ, Elliott WL, Fry DW. CI-1033, a pan-erbB tyrosine kinase inhibitor. Semin Oncol 2001;28(5) Suppl 16:80-85. 298. Nemunaitis J, Eiseman I, Cunningham C, Senzer N, Williams A, Lenehan PF, Olson SC, Bycott P, Schlicht M, Zentgraff R, Shin DM, Zinner RG. Phase 1 clinical and pharmacokinetics evaluation of oral CI-1033 in patients with refractory cancer. Clin Cancer Res 2005; 11(10):3846-3853 299. Zinner RG, Nemunaitis J, Eiseman I, Shin HJ, Olson SC, Christensen J, Huang X, Lenehan PF, Donato NJ, Shin DM. Phase I clinical and pharmacodynamic evaluation of oral CI-1033 in patients with refractory cancer. Clin Cancer Res 2007; 13(10):3006-3014. 300. Dewji MR. Early phase I data on an irreversible pan-erb inhibitor: CI-1033. What did we learn? J Chemother 2004; 16 Suppl 4:44-48. 301. Calvo E, Tolcher AW, Hammond LA, Patnaik A, de Bono JS, Eiseman IA, Olson SC, Lenehan PF, McCreery H, Lorusso P, Rowinsky EK. Administration of CI-1033, an irreversible pan-erbB tyrosine kinase inhibitor, is feasible on a 7-day on, 7-day off schedule: a phase I pharmacokinetic and food effect study. Clin Cancer Res 2004; 10(21):7112-7120 302. Rabindran SK, Discafani CM, Rosfjord EC, Baxter M, Floyd MB, Golas J, Hallett WA, Johnson BD, Nilakantan R, Overbeek E, Reich MF, Shen R, Shi X, Tsou HR, Wang YF, Wissner A. Antitumor activity of HKI-272, an orally active, irreversible inhibitor of the tyrosine kinase. Cancer Res 2004; 64(11):3958-3965. 303. Kwak EL, Sordella R, Bell DW, Godin-Heymann N, Okimoto RA, Brannigan BW, Harris PL, Driscoll DR, Fidias P, Lynch TJ, Rabindran SK, McGinnis JP, Wissner A, Sharma SV, Isselbacher KJ, Settleman J, Haber DA. Irreversible inhibitors of the EGF receptor may circumvent acquired resistance to Gefitinib. Proc Natl Acad Sci U S A 2005; 102(21):7665-7670. 304. Wissner A, Mansour TS. The development of HKI-272 and related compounds for the treatment of cancer. Arch Pharm (Weinheim) 2008; 341(8):465-477. 305. Wong KK, Fracasso PM, Bukowski RM, Lynch TJ, Munster PN, Shapiro GI, Janne PA, Eder JP, Naughton MJ, Ellis MJ, Jones SF, Mekhail T, Zacharchuk C, Vermette J, Abbas R, Quinn S, Powell C, Burris HA. A Phase I Study with Neratinib (HKI-272), an Irreversible Pan ErbB Receptor Tyrosine Kinase Inhibitor, in Patients with Solid Tumors. Clin Cancer Res 2009; 15(7):2552-2558. 306. Burstein HJ, sun Y, Dirix LY, Jiang Z, Paridaens R, Tan AR, Awada A, Ranade A, Jiao S, Schwartz G, Abbas R, Powell C, Turnbull K, Vermetti J, Zacharchuk C, Badwe R. Neratinib, an ireeversible ErbB receptor tyrosine kinase inhibitopr in patients with advanced ErbB2 positive breast cancer. J Clin Oncol 2010 [In Press]. 307. Fan M, Yan PS, Hartman-Frey C, Chen L, Paik H, Oyer SL, Salisbury JD, Cheng ASL, Li L, Abbosh PH. Diverse gene expression and DNA methylation profiles correlate with differential adaptation of breast cancer cells to the antiestrogens tamoxifen and fulvestrant. Canc Res 2006; 66:11954–11966. 308. Jones HE, Goddard L, Gee JM, Hiscox S, Rubini M, Barrow D, Knowlden JM, Williams S, Wakeling AE, Nicholson RI. Insulin-like growth factor-I receptor signalling and acquired resistance Medicinal Research Reviews 2012, 32(1), 166–215 to gefitinib (ZD1839; Iressa) in human breast and prostate cancer cells. Endocr Relat Cancer 2004; 11(4):793–814. 309. Silverman AP, Levin AM, Lahti JL and Cochran JR. Engineered Cystine-Knot Peptides that Bind αvβ3 Integrin with Antibody-Like Affinities. J Mol Biol 2009; 385:1064–1075. 310. Zhang M, Rosen JM. Stem cells in the etiology and treatment of cancer. Curr Opin Genet Dev 2006;16(1):60-64. Ms. Ruchi Saxena has done Masters in Biochemistry from the Department of Biochemistry, University of Lucknow, India and is presently pursuing Ph.D. under the supervision of Dr. Anila Dwivedi at the Division of Endocrinology at Central Drug Research Institute. She has qualified national level Entrance and Fellowship exams of Council of Scientific and Industrial Research and Indian Council of Medical Research. She is working as a Junior Research Fellow in a project on identification and development of novel therapeutic agent(s) for breast cancer. Dr Anila Dwivedi is a senior research scientist in the Division of Endocrinology at Central Drug Research Institute, Lucknow. She did her Masters in Biochemistry from Lucknow University and obtained Ph.D. in the area of Reproductive Biochemistry and Endocrinology from CDRI in 1986. Currently, she is pursuing research projects on Endocrine Related Cancers and Reproductive Biology. Her research projects are supported by Ministry of Health and Family Welfare, Govt of India and Indian Council of Medical Research, New Delhi, India. She has more than 50 peer- reviewed publications and three national / international patents.
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