1. No category

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Pulse Cyclophosphamide Therapy for Refractory Autoimmune
Thrombocytopenic Purpura
By Alex Reiner, Terry Gernsheimer, and Sherrill J. Slichter
Autoimmune thrombocytopenic purpura (AITP) is generally
a chronic disorder in affected adults. Twenty-five percent
of these patients will become refractory t o routine therapy
(corticosteroids and splenectomy), as well as most other
available agents. Intravenous pulsecyclophosphamide therapy was used t o treat 20 patients with severe refractory
AITP who hadpreviously failedt o achieve a sustained remission with a mean of 4.8 agents (range 2 t o 8). Patients received 1 t o 4 doses (mean 2.0) of 1.0 t o 1.5 g/m2 intravenous
cyclophosphamide per course. Of the 20 patients treated
with pulse cyclophosphamide therapy, 13 patients (65v0)
achieved a complete response (CR),four (20%) a partial response (PR), and three patients (15%) failed t o respond. Of
the 13 complete responders, eight have remained in remission with stable platelet counts during followup intervals
of 7 months t o 7 years (median 2.5 years). Five patients
developed recurrent AITP 4 months t o 3 years following a
CR.Of these, two patients responded t o subsequent courses
of pulse cyclophosphamide therapy with current remissions
of 1 and 4 years. Of the four patients who obtained a PR,
two remain in partial remission after 10 months and 4 years;
one relapsed after 18 months and, after retreatment, is still
in remission at 6 months. Of the patient characteristics examined, duration of disease was most strongly associated
with response t o pulse cyclophosphamide. Side-effects of
treatment included neutropenia (three patients, one of
whom developed staphylococcal sepsis), acute deep venous
thrombosis (two patients), and psoas abscess (one patient).
Intravenous pulse cyclophosphamide should be strongly
considered in the treatmentof patients with refractory AITP.
There is a relatively low incidence of side-effects, and it can
be administered easily on an out-patient basis.
0 7995 by The American Societyof Hematology.
A
lier study by Weinerman, et alZ6indicated a beneficial effect
of pulse cyclophosphamide in eight of 14 patients with AITP.
Seven years ago, we treated our first patient-a 15 year old
girl with severe refractory AITP who suffered an intracranial
hemorrhage-with pulse cyclophosphamide, and she remains
in long-term remission. We now report our experience using
pulse cyclophosphamide to treat 19 additional severely-affected, highly-refractory AITP patients.
UTOIMMUNE thrombocytopenic purpura (AITP) is a
disorder characterized by thrombocytopenia with
shortened platelet survival, normal to increased numbers of
bone marrow megakaryocytes, and elevated levels of platelet-associated immunoglobulin G (IgG).”’ Women are more
commonly affected than men. Bleeding manifestations are
variable, but are more likely to occur in older patients and
those with severe thromb~cytopenia.~.’
AITP is caused by
autoantibodies directed against platelet membrane glycoproteins (eg, GPIIb-IIIa, GPIb)*s9 that result in both removal
of the antibody-coated platelets from the circulation by the
reticuloendothelial system’0,” and defective platelet production and/or release of platelets from the bone ~ Z U T O W . ’ ~ - ’ ~
Initial therapy of AITP consists of corticosteroids, often
combined with intravenous gammaglobulin (W IgG) in severe episodes. There is a great predominance of the chronic
form of the disease in the adult patient’’ and most will ultimately require other forms of therapy, most commonly splenectomy. Together, corticosteroids and splenectomy induce
long-term responses in about 75% of chronic AITP patients.I6 The remaining 25% of patients who are refractory
to standard therapy constitute a subgroup with a significantly
higher mortality rate compared with those who respond to
corticosteroids and/or splenectomy.’6 Other treatment options are available for patients with refractory AITP,but
response rates 2re generally low and unpredictable. The initial response rates for other agents such as vinca alkaloids,
danazol, low-dose oral cyclophosphamide, azathioprine, and
colchicine are less than 50%, with long-term response rates
much lower.I6 More recently, other agents such as a-interferon,” cyclosporine,’*IV IgG,” ascorbic acid:” staph protein A immunoadsorption:’ anti-Fc receptor monoclonal antibody:‘ and combination chemotherapyz3have been used
in the treatment of refractory AITP, but the utility of these
agents either has been unsatisfactory or remains to be confirmed in larger clinical trials.
Intermittent intravenous cyclophosphamide (pulse therapy) has been reported as an effective treatment for various
autoimmune diseases including nephritis associated with
systemic lupus erythematosis (SLE).”.25In addition, an earBlood, Vol85, No 2 (January 151,1995: pp 351-358
MATERIALS AND METHODS
Patient selection. Because of our interest in the care and management of patients with AITP, we are often consulted by community
physicians to discuss treatment options for their patients with refractory disease. Based on our success with the initial patient (patient
no. 1) treated with pulse cyclophosphamide, subsequent referrals
were routinely advised to initiate a similar therapeutic regimen. The
diagnosis of AITP in the study patients was made on the basis of
thrombocytopenia unrelated to any underlying viral infection, collagen vascular disease, malignancy or medication, morphologically
normal bone marrow aspirate with normal to increased numbers of
megakaryocytes, and absence of splenomegaly. Patients were considered for therapy if either: (1) during an acute initial or recurrent
episode of AITP, platelet counts could not be increased to a safe
level despite treatment with multiple modalities; or (2) if chronic
AITP could not be managed with acceptable doses of corticosteroids
or other agents.
From Puget Sound Blood Center: and theDivision of Hematology,
University of Washington School of Medicine, Seattle, WA.
Submitted May 2, 1994: accepted September 15, 1994.
Supported by Grant No. HL 47227 fromthe National Heart, Lung,
and Blood Institute, National Institutes of Health.
Address reprint requests to Sherrill J. Slichter, MD, Director,
Medical & Research Division, Puget Sound Blood Center, 921 Terry
Ave. Seattle, WA 98104-1256.
The publication costs of this article were defrayed in part by page
charge payment. This article must therefore be hereby marked
“advertisement” in accordance with 18 U.S.C. section 1734 solely to
indicate this fact.
0 1995 by The American Society of Hematology.
oooS-497I/s5/8502-0014$3.00/0
35 1
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352
Pulse cyclophosphamide
therapy.
Each treatment course of
high-dose cyclophosphamide therapy consisted of 1.0 to I .5 g/m' of
cyclophosphamide given by rapid intravenous infusion and repeated
at four-week intervals. The number of doses administered per treatment course ranged from one to four, with a meanof 2.0. At the
time of initiation of cyclophosphamide therapy, all patients were
simultaneously receiving corticosteroids, and several were receiving
other agents as well.
Treatment response criteria Clinical response to cyclophosphamide wasdefined as follows: complete response (CR) = platelet
X IO9& partial response (PR) = increase in platelet
count ,150
count to 2 5 0 X 109/L;or no response (NR).
Platelet antibody assays. Platelet-associated and free circulating
platelet antibodies were detected using both '2sI-radiolabeled(RIA)
and enzyme-linked (ELISA) platelet antiglobulin assays. The direct
assay was performed using the patient's autologous platelets if the
platelet count was above 10 to 20 X 109/L. In the indirect assays,
patient serum was tested against platelets from one or more random
normal group 0 blood donors. Data is not reported for the indirect
assays unless the patient had never beenpreviously pregnant or
transfused so that an alloantibody reacting with donor platelets could
be excluded as the basis for a positive test result.
Peripheral whole blood collected in 10% potassium-EDTA was
centrifuged at 350s for 10 minutes to obtain platelet-rich plasma
from patients or random donors. For the ELISA platelet antiglobulin
assays, the platelets were washed three times with 0.01 mol/L Tris
pH 7.5 containing 0.145 mol/L NaCl and 1 mmol/L EDTA, and the
platelet concentration was adjusted to 100 X IOY/L. Five X 10'
platelets were added to wells of a 96-well microtiter plate (NUNC,
Roskilde, Denmark). The platelets were bound to the wells by centrifugation at 1 0 0 0 ~
for 10 minutes. Plates were washed three times
with phosphate buffered saline (PBS), then blocked with 100 pL of
5% human albumin (New York Blood Center, Melville, N Y ) for 30
minutes at room temperature. Fifty pL of fresh (less than 24 hours
old) patient or pooled normal serum diluted 1:2and 1:4 in5% human
albumin was added to the microtiter wells of each platelet sample
and incubated at 37°C for 60 minutes. Plates were then washed six
times with PBS, and 50 pL of one of four different alkaline phosphatase-conjugated antiglobulin reagents diluted in 5% human albumin
were added and incubated at room temperature for 30 minutes. The
four detecting reagents were: (1) monoclonal antihuman IgG (ICN
Biomedicals, Costa Mesa, CA) diluted 1 :800; (2) monoclonal antihuman IgG, (The Binding Site, Birmingham, UK) diluted 1:400; (3)
goat antihuman IgM (Sigma, St Louis, MO) diluted 1:500; and (4)
Staph Protein A (Boehringer, Mannheim, Germany) diluted 1:800.
After washing six times with PBS, 50 pL of substrate (3.4 mg/mL
p-nitrophenylphosphate in 0.05 m o l n carbonate 1 mmol/LMgCl,
pH 9.8) was added to each well; the platelets were sealed with plastic
sealing tape and incubated at 37°C for 50 minutes. The reaction was
stopped by the addition of 50 pL of I mol/L NaOH. Absorbance
was measured using a Bio-Tek microtiter plate reader (Winooski,
VT). A positive platelet antibody result is indicated if the OD is
over two standard deviations above that of the pooled normal serum
for any of the four detecting reagents. Serum pools were obtained
from 20 to 30 previously untransfused male donors who were type
A or AB. In our laboratory, the coefficient of variation of the OD
for pooled normal serum is approximately 30%. Reference alloantisera wereused for standardization of the ELISA and as positive
controls.
The platelet antiglobulin radioimmunoassay was performed using
'251-labeled anti-IgG and anti-C, asthe detecting reagents as described previously." An elevated level of platelet antibody detected
using any one (or more) of thesix total antiglobulin reagents in
either the ELISA or theRIAwas
considered a positive platelet
antibody test.
REINER,GERNSHEIMER,
AND SLICHTER
RESULTS
Patient characteristics. The clinicalcharacteristics
of
the 20 patientswith refractory AITP treated with pulse cyclophosphamide are shown in Table 1. Fourteen patients were
women, and sixwere men. Patient ages ranged from 15 to 79
years with a mean of 50 years. Concurrent diseases included
diabetes mellitus in three patients (no.8, 13, and 20), autoimmune hemolytic anemia in two patients(no. 14 and 16),
hypothyroidism in two patients (no. 6 and 14), and multiple
sclerosis in one patient (no. 2). One of nine patients tested
had a positive antinuclear antibody (ANA; patient no. 10).
The median duration of AITP before pulse cyclophosphamide therapy was six months and ranged from one month
to 28 years. Bleeding manifestations were present in 16 patients. These mainly consisted of skin and mucosal bleeding,
except for patient no. 1 who suffered an intracranial hemorrhage. Of the 20 patients, nine received pulse cyclophosphamide during theirinitial episode of AITP (patients no. I
through g), while 11 weretreated during an AITP relapse
(patients no. 10 through 20). Of the latter patients, four were
in first relapse (no. I I through 14), one was in third relapse
(no. lo), and six patients had long-standing recurrent AITP
with fouror morerelapses (no. 15 through 20).The20
patients had beentreatedpreviously
with a mean of 4.8
different agents (range,2 to8)before cyclophosphamide
therapy. All 20 patients had received corticosteroids, and 19
had undergone splenectomy. Two patients had also undergone an accessory splenectomy (no. I8 and 20). Other previous therapies included vinca alkaloids ( 1 5 patients), IV IgG
(IS patients),danazol (8patients), plasmapheresis (4 patients), anti-D IgG (3 patients), low-dose oral cyclophosphamide (3 patients),azathioprine (3 patients), colchicine(2
patients), and ascorbic acid,ProteinAimmunoadsorption,
and vinca-loaded platelets ( I patient each).
In addition to corticosteroid therapy, I3 courses of cyclophosphamide were administered concurrently with IV IgG,
three courses with danazol, and one course with vincristine.
In patients no. 10, 1 I, and 16, danazol had been administered
for 3 weeks, 10 weeks, and10 days before initiation of pulse
cyclophosphamide therapy,respectively,without
evidence
of an increase in platelet count. Although patient no. 10 had
transiently responded to vincristine, he had been receiving
this agent for 1 month before initiation of pulse cyclophosphamide without effect.
The mean nadir platelet count precyclophosphamide for
the 20 patients was 7 X I O 9 L (range, I to20 X l0'L)
(Table 2). At the time of initiation of cyclophosphamide
therapy,themeanplatelet
count was 68 X I O ' L (range, I
to 534 X IOq/L). This elevation from baseline was due to
the acute effect of IV IgG or high-dose corticosteroids in
six of the patients.
Response to pulse
cyclophosphamide
therapy.
Responses of the 20 refractory AITP patients to pulse cyclophosphamideare illustrated in Fig 1 andsummarized in
Table 2. The meanpeakplatelet
count followingthe27
treatment courses of pulsecyclophosphamidewas261
X
1 0 " L (range, 6 to 745 X lo9&). Based onour response
CR. four(20%)
criteria, 13 patients (65%) achieveda
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PULSE
FOR AITP
353
Table 1. Patient Characteristics and Previous and Concurrent Therapy
Patient No.
5
F166
F165
F11
1
2
3
4
SexIAge
FP7
M128
5
MI24
6
7
8
9
10
F141
F115
F159
M164
Duration
of AITP
Bleeding Manifestations*
Previous Therapy
4 m0
Epistaxis, GU, intracerebral
GU
Skin, epistaxis
Epistaxis, gingival, GU
Skin, epistaxis
Skin, gingival
GI
Epistaxis, GU
None
None
6 m0
6 m0
8 mo
Skin
Skin
Skin, gingival
CS,
1 m0
1 mo
1 mo
1 mo
2 mo
2 mo
4 m0
6 m0
8 mo
CS,
CS,
CS,
CS,
CS,
CS,
CS,
CS,
CS,
CS,
splen, va, vlp, IV IgG. pher
splen, va, IV IgG, anti-D, pher
splen, IV IgG
splen, IV IgG
splen, va, IV IgG
IV IgG, pher
splen, va, dz, IV IgG, colch, aa
splen, va, IV IgG
splen
splen, va, IV IgG
splen, va, dz, IV IgG, aza
splen, va, dz, Id cy
splen, dz
11
12
13
W42
14
15
F136
F140
2 yr
Epistaxis
None
CS,
3 vr
CS,
splen, va, IV IgG
splen, va, dz, IV IgG, aza, pher, prot A
16
F138
5 vr
Skin, gingival, GU
CS.
splen,
dz,
va,
17
M179
6 yr
GU
Epistaxis,
va
CS, splen,
18
19
F151
Mi7 1
10 yr
15 yr
CS.
20
FP2
28 yr
None
Skin, epistaxis,
conjunctival
GU
Mi75
F134
CS,
CS,
IV IgG, colch
Current Therapy
CS
CS,
IV IgG
CS
CS,
CS,
IV IgG
IV IgG
CS
CS
CS
IV IgG
a) CS, va, IV IgG
b) CS, dz
c) IV IgG
CS, IV IgG, dz
CS, IV IgG
a) CS
b) None
CS,
CS
a) CS
b) CS,
a) CS,
b) CS,
c) CS,
a) CS,
IV IgG
dz
IV IgG
IV IgG
IV IgG
b) CS
CS,
CS.
splen, va, dz, IV IgG, aza, anti-D
splen, va, Id cy, IV IgG, anti-D
CS,
splen, va, dz, Id cy
CS
IV IgG
CS
Concurrent therapy is listed foreach treatment course of pulse cyclophosphamide received by each patient. a, b. and c represent sequential
treatment programs in the same patient.
Abbreviations: CS, corticosteroids: splen, splenectomy; va, vinca alkaloids; dz, danazol; Id cy, low dose cyclophosphamide; aza, azathioprine;
anti-D, anti-RhD; colch, colchicine; aa, ascorbic acid; vlp, vinca-loaded platelets; protA, protein A immunoadsorption: pher, plasmapheresis; !V
IgG, intravenous immune globulin; GU, genitourinary; GI, gastrointestinal.
* Bleeding manifestations at the time of initiationof pulse cyclophosphamide.
achieved a PR, and three (15%) had NR; thus, the overall
response rate to the first treatment course with pulse cyclophosphamide was 85%. The mean time to response was 7
weeks and ranged from 1 to 16 weeks.
Of the 13 complete responders, eight have remained in
remission with stable platelet counts during followup intervals of 6 months to 7 years (median, 2.5 years). This includes
the index patient (no. l), who fully recovered from an intracranial hemorrhage and has been well for 7 years. Five patients developed recurrent AITP 4 months to 3 years following a CR. Of these, two patients (no. 13 and 16) responded
to subsequent courses of pulse cyclophosphamide. Patient
no. 13 relapsed after 9 months, then achieved a second CR
with pulse cyclophosphamide that has persisted for 4 years.
Patient no. 16 relapsed 3 years after her first CR with pulse
cyclophosphamide, then achieved a second CR with pulse
cyclophosphamide that lasted 10 months and finally a third
CR, which has persisted for 1 year. Adding these two patients
to the eight who remain in CR after their first treatment
course with pulse cyclophosphamide gives a long-term CR
rate of 10120 or 50% with a median followup of 2.5 years.
Five of these patients responded during their initial episode
of AITP, and five of these were patients with a history of
relapsed AITP.
The three other patients who relapsed after a first CR to
pulse cyclophosphamide also received additional courses of
pulse cyclophosphamide. Patient no. 15 relapsed 9 months
after her CR, then responded very briefly to a second treatment course with pulse cyclophosphamide. She subsequently
failed trials of methotrexate, a-interferon, 2-chlorodeoxyadenosine, and Protein A immunoadsorption. Currently, her
platelet count is maintained above 50 X 109Lon a single
dose of IV IgG repeated every three weeks. Patient no. 10
relapsed 4 months after his first CR, achieved a second CR
with pulse cyclophosphamide that lasted 5 months, then received a third treatment course with pulse cyclophosphamide
without response. He subsequently failed a trial of anti-D
and, over the past several years, has had several more recurrences of AITP that respond variably to a combination of
corticosteroids, IV IgG, low-dose cyclophosphamide, and
danazol. Patient no. 2 relapsed 1 year after her CR. Because
her first treatment course of pulse cyclophosphamide was
complicated by severe neutropenia and staph sepsis, she was
begun on intravenous cyclophosphamide at a lower dose of
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354
GERNSHEIMER,
REINER,
AND SLlCHTER
Table 2. Response to Pulse Cyclophosphamide Therapy
No. of Doses/
Patient No.
1
2
3
4
5
6
7
8
9
10a
10b
1oc
11
12
13a
13b
14
15a
15b
16a
16b
16c
17a
17b
18
19
20
Treatment
Pre*
Count
Program
Time to
X
1091~
l
<l
1
2
1
2
3
3
4
2
2
2
1
3
2
1
2
2
2
3
2
1
1
2
2
4
2
3
1
4
4
6
6
9
5
6
9
14
2
9
8
20
16
6
3
12
10
9
5
10
20
10
6
5
Postt Count
x 109/L
Response
530
215
56
198
369
180
79
67
457
315
377
10
260
10
146
400
440
373
176
547
745
279
124
63
390$
6
234
CR
CR
PR
CR
CR
CR
PR
PR
CR
CR
CR
NR
CR
NR
CR
CR
CR
CR
CR
CR
CR
CR
PR
PR
NR
NR
CR
Response
(wk)
4
8
10
1
10
9
6
16
8
Response
7 vr
1 vr
4 vr
8 mo
7 vr
6 mo
10 mo
5 mo
2
2 vr
4 mo
5 mo
16
3 vr
2
8
6
8
6
4
2
2
10
10
9 mo
8
8
Status
Current
Duration
4 vr
1 vr
9 mo
2 mo
CR
Deceased (unknown cause)
PR
CR
CR
CR
PR
Deceased (complications of diabetes)
CR
PR t o dz, Id cy, CS, IV IgG
CR
Deceased (bleeding; refused additional therapy)
CR
CR
PR t o IV IgG
3 Yr
10 mo
1 vr
18 mo
6 m0
5 yr
CR
PR
CR to prot A
Deceased (complications of another therapy)
CR
a, b, c, represent sequential treatment programs in the same patient.
Abbreviations: CR. complete response; PR, partial response; NR, no response; dz, danazol; Id cy, low dose cytoxan;
IgG, intravenous immunoglobulin; prot A, protein A immunoadsorption.
* Nadir platelet count precyclophosphamide.
t Peak platelet count postcyclophosphamide.
Represents transient response to IV IgG.
CS,
corticosteroids; IV
*
500 to 750 mg weekly. The patient died two months later
of unknown causes while in a nursing home with a platelet
count of 32 X 109/L.
Four of the 20 patients achieved a PR following their first
treatment course of pulse cyclophosphamide. Two of these
patients (no. 3 and 7) remain stable off all medications after
4 years and 10 months, respectively. Patient no. 3 presented
with a platelet count of <S X 109/Lassociated with intermittent epistaxis and bruising. She initially responded to pulse
cyclophosphamide with a platelet count of 50 X 109/Lthat
persisted for 6 months. Her platelet count subsequently decreased to 20 X lo9& but she has maintained a platelet
count in this range off all medications with resolution of
bleeding symptoms for the past 4 years. Patient no. 8 relapsed 5 months after a PRto cyclophosphamide therapy
and died 1 month later of complications of diabetes mellitus.
Patient no. 17 relapsed 18 months after a first PR, then
achieved a subsequent PR that has been stable for 6 months
off all therapy following a second treatment course of pulse
cyclophosphamide therapy.
Three patients with chronic recurrent AITP failed to respondto pulse cyclophosphamide therapy. All were previously refractory to corticosteroids, splenectomy, danazol,
and vincristine therapy. Two patients had failed to respond
to anti-D. Two had previously failed therapy with low-dose
oral cyclophosphamide. Patient no. 18 has since achieved a
CR with Protein A immunoadsorption that has persisted for
two months. Patient no. 12 was refractory to corticosteroids,
splenectomy, and IV IgG, then responded transiently to vincristine and danazol. He failed to respond to either low-dose
oral or intravenous pulse cyclophosphamide therapy and died
3 months later with a platelet count of < l 0 X 109/L of
uncontrolled hemorrhage and anemia after refusing further
supportive transfusion therapy. Patient no. 19 died of complications following treatment with an anti-Fc receptor monoclonal antibody.
Plateletantibody data. Platelet antibody studies were
performed for 12 of the 20 patients before pulse cyclophosphamide treatment. Platelet-associated antibodies were detected in l l of these 12 patients. Ten of the patients had
free, circulating platelet antibodies. Interestingly, the one
patient who was negative for both platelet-bound and free
antibody (no. 19) did not respond to pulse cyclophosphamide
therapy.
Response versus patient characteristics. The relationship of several patient variables to their initial treatment
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355
PULSE CYCLOPHOSPHAMIDE FOR AITP
800
l
600
/I
400
200
Pre
Post
Fig 1. Platelet responses to pulsecyclophosphamide.Thenadir
precyclophosphamide platelet countandpeakpostcyclophosphamMe platelet count is plotted for each patient. For patients treated
with more than one course, the resutts of each treatment is represented.
response to pulse cyclophosphamide is summarized in Table
3. Because of the small number of patients (particularly in
the NR category), firm conclusions cannot be drawn. The
duration of AITP appears to be the strongest determinant of
patient response to pulse cyclophosphamide. The median
duration of AITP in responders (CR + PR) versus nonresponders is 6 months versus 10 years ( P value = .l0 by
Mann-Whitney rank sum test). While nine patients treated
during their initial episode of (primary) AITP as well as
eight patients with recurrent AITP responded to pulse cyclophosphamide, the three non-responders all had recurrent
AITP ( P value = .22 by Fisher exact test). From the data in
Table 3, there is also a suggestion that women and younger
patients respond better to pulse cyclophosphamide ( P values
= .20 and .15, respectively). Finally, when the 27 treatment
courses of pulse cyclophosphamide are analyzed individually, there is no correlation between number of doses and
treatment outcome.
Complications of pulse cyclophosphamide therapy.
Side-effects occurred during six of the 27 treatment courses
(22%). Neutropenia was the most frequent complication of
pulse cyclophosphamide therapy and occurred during three
of the 27 treatment courses (11%). In two patients (no. 3
and 15), the neutropenia was mild (nadir neutrophil count
1.0 and 1.5 X lo9&, respectively). Patient no. 2, however,
developed severe neutropenia (neutrophil count = 0.1 X lo9/
L) complicated by an episode of staphylococcal sepsis. This
patient eventually recovered and maintained a CR for one
year, but subsequently died shortly after a second course of
cyclophosphamide given at a lower dose (500 to 750 mg
weekly). The cause of death is unknown.
Two patients (no. 10 and 16) developed acute deep venous
thrombosis coincident with a rapid CR to therapy (platelet
counts of 298 X 109/Land 745 X lo9&, respectively, at the
time of the thrombosis). No known risk factors for venous
thrombotic disease were present in either patient.
Finally, patient no. 17 developed a psoas abscess following the first dose of pulse cyclophosphamide, necessitating
a delay of the second dose by 6 weeks. The psoas abscess
was not accompanied by neutropenia in this patient, but he
had been receiving prolonged therapy with corticosteroids.
Following a relapse 1 year later, the patient received another
two doses of pulse cyclophosphamide therapy without complications and again attained a PR.
Although 12 of the 27 cyclophosphamide treatment
courses were initiated while patients were hospitalized because of their bleeding manifestations and low platelet
counts, patients who were more stable could be treated as
outpatients because of the low incidence of side-effects.
No long-term side-effects of pulse cyclophosphamide
have been noted in any of our patients to date. In particular,
none of the 20 patients have developed a secondary malignancy (median followup since first cyclophosphamide dose
is 2 years, range 3 months to 7 years).
DISCUSSION
We report the responses of 20 clinically-severe and
highly-refractory AITP patients to pulse cyclophosphamide.
Bleeding symptoms were present at the time of treatment in
16 patients, including intracranial bleeding in the initial patient. More than halfof the patients had recurrent A m ,
including six patients with chronic, long-standing AITP
marked by four or more relapses. Furthermore, all the patients had been heavily treated before receiving pulse cyclophosphamide. Each patient had failed to respond to an aver-
Table 3. Patient Characteristics Based on Response to Treatmant
CR
Sex (WM)
112
311
Mean age (yr)
AITP median duration
Priman//Recurrent
Mean no. doses cyclophosphamide
Presence of antibody
(n = 13)
PR
(n = 4)
1013
46
6mo
617
1.9
7/7
50
5mo
311
2.6
3/3
NR
(n = 3)
66
10yr
OB
2.3
1/2
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356
age of 4.8 different agents, including corticosteroids in all
20, and splenectomy in 19.
The evaluation of patient responses to pulse cyclophosphamide may be complicated by two factors. First, approximately five toten percent of patients with AITP recover
spontaneously.’h~’7~28
However, the fairly short and predictable time interval between pulse cyclophosphamide treatmentand rise in platelet count (mean 8 weeks after first
dose) in most of our patients is consistent with a therapeutic
effect. Second, in a few of our patients, evaluation of response to cyclophosphamide may be complicated by a short
time interval between previous therapies and administration
of cyclophosphamide, or by concurrent treatment with other
agents. In three patients treated during an initial episode of
AITP (no. 1, 2 and 5), the interval between vinca alkaloid
treatment and initiation of pulse cyclophosphamide was relatively short, but vinca alkaloids rarely induce a long-term
response. Almost half of the 27 treatment courses were administered concurrently with intravenous IgG, butnotin
doses reported to induce a long-term response.” Four cyclophosphamide responses were associated with concurrent danazol (patients no. 10, 11, and 16) or vinca alkaloid therapy
(no. lo), but the interval toand duration of response are
more consistent with a response to pulse cyclophosphamide
therapy.
In this series of 20 highly refractory patients, 17 patients
had either a CR or PR to their initial course of pulse cyclophosphamide (one to four doses of 1 to 1.5 g/m2) for an
overall response rate of 85%. Furthermore, 10 patients (50%)
in the series have had a sustained response to their initial
treatment. In addition, three of the initially-responsive patients who relapsed responded to a second and/or third treatment course of pulse cyclophosphamide and are currently
stable. Thus, the cumulative long-term response rate is 13
of 20 (65%) with a mean followup of 2.9 years. These results
are superior to those of standard secondary AITP agents
such as vinca alkaloids, danazol, oral cyclophosphamide,
and azathioprine. At best, these agents have response rates
of approximately 50%, but sustained response rates are in
the range of only 5 to 25%.16
Our favorable results with pulse cyclophosphamide are
comparable to three other studies. Figueroa, et al’’ recently
reported responses in eight (six complete, two partial) of
10 severely-affected, highly-refractory AITP patients treated
with cyclophosphamide-based combination chemotherapy.
Five of the responses (four complete and one partial) were
sustained. These patients received between 3 and 8 monthly
cycles of a chemotherapy regimen that included cyclophosphamide at total doses approximately the same asusedin
our study (-0.5 g/m’ given every 2 weeks) and corticosteroids along with either vincristine, procarbazine, and/or etoposide. Our data suggest that the most important component
of these combined treatment regimens was cyclophosphamide, and that the other agents maynot be required to
achieve the desired result. Single-agent therapy would
clearly reduce costs, and possible complications, of therapy.
Secondly, Boumpas et alZ9reported complete responses in
each of seven refractory patients with SLE-associated immune thrombocytopenia treated with one to four doses of
REINER, GERNSHEIMER, AND SLICHTER
cyclophosphamide at 0.75 to 1.0 g/m2.Four of these patients
had sustained responses with a mean followup of 5.6 years.
Thus, single-agent pulse cyclophosphamide appears tobe
beneficial in bothprimary and SLE-associated AITP. Finally,
Weinerman et alZhreported responses in eight of 14 patients
with immune thrombocytopenia treated with varying schedules of intermittent cyclophosphamide in doses ranging from
300 to 600 mg/m’. These patients had previously failed corticosteroids and, in some cases, splenectomy. Four of the responders had disseminated SLE. Six of the responses were
sustained with followup ranging between 15 and 20 months.
The slightly lower response rate in this earlier report may
be due to the lower dose of pulse cyclophosphamide compared with our study andthose of Figueroa et a]’’ and Boumpas et a12’
The mechanism of action of pulse cyclophosphamide in
autoimmune disorders appears to be suppression of both T
and B lymphocyte numbers and function,” which leads to
diminished autoantibody p r ~ d u c t i o n .In
~ ~previous
,~~
studies
of AITP patients treated with cyclophosphamide or cyclophosphamide-based combination chemotherapy, clinical response was associated with reduction of platelet antibody
level~.~’~’’
In our series, postcyclophosphamide platelet antibody studies were performed in only three patients; two of
the three patients showed disappearance of platelet autoantibody following a complete, persistent response to pulse cyclophosphamide. In one patient (no. l ) , platelet autoantibody
disappeared within 4 weeks of treatment. The other (no. 5)
had a more gradual decline in antibody level over a period
of several years. The third patient (no. 16) had persistent
platelet autoantibody 2 months after treatment that resulted
in a transient CR, but followup platelet antibody testing was
not performed.
Several patient characteristics were examined for an association with pulsecyclophosphamide treatment outcome. Because of the small number of patients studied, none of the
associations reached statistical significance. Of those examined, shorter disease duration was most strongly associated
with response to pulse cyclophosphamide (P value = .IO),
and patient age, sex, and phase of disease were all marginally
significant as well. The association of shorter disease duration has beennoted for AITP response to oral low-dose
cyclophosphamide as
Splenectomized patients have
also been reported to have a better response rate to oral
cyclophosphamide,33but we are unable to confirm this association with pulse cyclophosphamide because ail but one of
our patients had undergone splenectomy.
Acute side-effects occurred during six of 27 (22%) of
the pulse cyclophosphamide treatment courses. Neutropenia
occurred in three patients, but was severe in only one patient
in whom staphylococcal sepsis developed. The occurrence
of deep venous thrombosis in two patients was associated
with a rapid and complete response to pulse cyclophosphamide.Although cyclophosphamide itself is not associated
with hypercoaguability, it is possible that the rapid increase
in platelet count may have induced a transient hypercoaguable state due to the presence of circulating, immature hyperfunctional platelets that are thought to circulate in AITP
patients.34 However, the acute increase in platelet count
From www.bloodjournal.org by guest on December 29, 2014. For personal use only.
PULSE CYCLOPHOSPHAMIDE FOR AITP
sometimes seen postsplenectomy for this and other disorders
is not commonly associated with deep venous thrombosis
unless other intrinsic abnormalities of the blood are present
and associated with abnormal platelet function such as myeloproliferative disorders.35336
Other known side-effects of cyclophosphamide such as nausea, vomiting, alopecia, and
hemorrhagic cystitis were not noted in this series.
Although no long-term side-effects of pulse cyclophosphamide were noted in our patients, an association between
cyclophosphamide and secondary cancers has been wellestablished. In patients with rheumatologic disorders treated
with oral cyclophosphamide, the risk appears to be related
to cumulative cyclophosphamide dose and duration of thera ~ y . Krause3*
~’
reported three patients with AITP who developed acute myeloid leukemia 2 to 4 years after receiving
low-dose oral cyclophosphamide. An increased risk of secondary malignancy has also been noted in patients treated
with pulse cyclophosphamide for primary neoplasms3’ and
as a conditioning regimen preceding bone marrow transplantation for aplastic anemia.@The incidence of secondary
cancers in patients with autoimmune disease treatedwith
pulse cyclophosphamide is unknown, but appears to be lower
than with continuous oral cycloph~sphamide.~~
To date, there
have been five cases reported of malignancy complicating
pulse cyclophosphamide in SLE patient^.^'^^'.^'
Another potential complication of pulse cyclophosphamide is sterility, although this side-effect is also less common
than with continuous low-dose cyclophosphamide therapy.
Nevertheless, infertility has been reported in over half of the
women receiving pulse cycloph~sphamide.~~
The role of pulse cyclophosphamide in the treatment of
refractory AITP requires careful consideration of the relative
benefits and risks. Our data suggest that pulse cyclophosphamide is an effective treatment for refractory AITP and should
be strongly considered in severely-affected patients who do
not respond to standard therapy. It may be particularly efficacious in elderly patients in whom the long-term risks of
malignancy and sterility are less of a concern than in younger
patients, as well as in patients for whom splenectomy is a
high-risk procedure. Nevertheless, given the relatively high
mortality rate of refractory AITP, treatment at any age may
be justified. The optimum dose and treatment schedule of
pulse cyclophosphamide remain to be determined.
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1995 85: 351-358
Pulse cyclophosphamide therapy for refractory autoimmune
thrombocytopenic purpura [see comments]
A Reiner, T Gernsheimer and SJ Slichter
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