- Email: [email protected]
Long-term efficacy and limitations of cyclophosphamide in myasthenia gravis
Journal of Clinical Neuroscience 21 (2014) 1909–1914
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Study
Long-term efficacy and limitations of cyclophosphamide in myasthenia gravis M. Nagappa a, M. Netravathi a, A.B. Taly a,⇑, S. Sinha a, P.S. Bindu a, A. Mahadevan b a b
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka 560 029, India Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
a r t i c l e
i n f o
Article history: Received 17 September 2013 Accepted 5 March 2014
Keywords: Cyclophosphamide Immune therapy Myasthenia gravis
a b s t r a c t Myasthenia gravis (MG) is a chronic autoimmune disorder with a fluctuating clinical course. The aim of immunotherapy is to bring about long-term remission. We evaluated the safety and efficacy of cyclophosphamide in generalized MG. We also highlight the limitations of cyclophosphamide therapy in inducing long-term remission. Data from 22 patients with generalized MG who received cyclophosphamide therapy were analyzed in terms of its safety and outcome. Twelve patients completed at least six pulses of intravenous cyclophosphamide therapy, and all improved symptomatically at 6 months. At 1 year, only seven patients reported sustained benefit and five had discontinued oral pyridostigmine. During a follow-up period of 56.67 months, all but one patient relapsed and required alternative immunomodulatory therapy. The average time to remission after the initiation of intravenous pulse cyclophosphamide (n = 12) was 3.6 months (standard deviation [SD] 1.6 months, range 1–6 months), while the mean duration of remission was 20.3 months (SD 8.8 months, range 12–39 months). Forty-six adverse events were documented in 11 patients over 127 cyclophosphamide pulses. Most of the adverse events were managed symptomatically. In four patients, cyclophosphamide had to be discontinued due to adverse events. Intravenous pulse cyclophosphamide is effective in the management of MG; however remission may be short, necessitating long-term follow-up and alternative immunomodulation. Careful monitoring for adverse events should be mandatory. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Cyclophosphamide is a cell-cycle non-specific anti-proliferative agent that, following hepatic biotransformation to active metabolites, exerts its cytotoxic action primarily by covalent cross-linking of nucleic acids, resulting in unpaired replication of DNA and damage to the DNA structure. Initially developed as a broad spectrum anti-neoplastic agent, cyclophosphamide also has established efficacy and tolerability in a variety of non-neoplastic immune mediated diseases such as systemic lupus erythematosus, rheumatoid arthritis, aplastic anemia, pemphigus, autoimmune neuropathies, and Wegener’s granulomatosis [1–4]. Myasthenia gravis (MG) is a prototype autoimmune disorder characterized by auto-antibody production against the neuromuscular junction. Apart from thymectomy and symptomatic treatment with cholinesterase inhibitors, the mainstay of MG treatment consists of immunosuppression. Steroids are the most commonly used immune-suppressive agents, but are sometimes ⇑ Corresponding author. Tel.: +91 80 2699 5150; fax: +91 80 2656 4830. E-mail address: [email protected] (A.B. Taly). http://dx.doi.org/10.1016/j.jocn.2014.03.019 0967-5868/Ó 2014 Elsevier Ltd. All rights reserved.
associated with significant side effects and poor therapeutic response. Various alternative agents in MG include azathioprine, methotrexate, mycophenolate mofetil, rituximab, tacrolimus and cyclosporine as well as cyclophosphamide. There is a limited range of therapeutic options for ‘‘difficult-to-treat’’ or ‘‘refractory’’ MG, and cyclophosphamide is one of the effective therapies that has been neglected in the literature. It is inexpensive compared to other immunosuppressive agents like rituximab and is widely available. Additionally, it has the advantage of a rapid onset of action compared to azathioprine and mycophenolate mofetil [5–7], and thus lends itself to use in elderly patients, and patients with severe MG or respiratory muscle weakness requiring mechanical ventilation. The efficacy of cyclophosphamide was initially demonstrated in animal models of experimental autoimmune MG [8]. Interestingly, cyclophosphamide has been also shown to induce tolerance to human immunoglobulin in passive transfer models of MG [9]. Subsequent studies have demonstrated that cyclophosphamide is safe and effective in inducing durable remission in MG [5,10–13]. However, to our knowledge only one study has systematically evaluated the long-term outcome of cyclophosphamide therapy in MG [12]. The aim of this study was
1910
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914
to evaluate the short and long-term efficacy and safety of cyclophosphamide in generalized MG.
2. Materials and methods Data from 22 patients with generalized MG who received cyclophosphamide therapy and were followed up at a single neurology unit from 1997 to 2012 at the National Institute of Mental Health and Neurosciences, Bangalore (a university teaching hospital and tertiary care referral centre for neurological and neuropsychiatric patients in south India) were retrospectively analysed. The diagnosis of MG was established by the presence of fluctuating and fatigable weakness of voluntary muscles particularly involving the oculomotor and bulbar muscles and confirmed by (i) electrophysiological testing demonstrating decremental response on supramaximal 3 Hz repetitive nerve stimulation, defined as more than 10% reduction in the amplitude of the negative peak of the compound muscle action potential from the first to the fourth response; (ii) pharmacological testing with neostigmine injection showing unequivocal improvement in muscle strength; or (iii) serological testing demonstrating the presence of antiacetylcholine receptor antibody (AChR Ab). Testing for antibodies to muscle specific tyrosine kinase was not available. The presence of active MG or lack of remission was defined as the presence of any of the following with or without oculomotor involvement in the form of diplopia and ptosis: (i) bulbar involvement (nasal twang, nasal regurgitation, choking or cough upon swallowing, necessitating tube feeding); (ii) respiratory difficulty necessitating mechanical ventilation; or (iii) fatigable limb weakness. The clinical status was assessed using the Myasthenia Gravis Foundation of America (MGFA) Task Force guidelines [14]. The parameters assessed at baseline prior to the initiation of cyclophosphamide therapy included demographic variables of age and sex, clinical features of MGFA grade, duration of MG, number of myasthenic crises, coexisting autoimmune disorders, AChR Ab status (binding antibodies to AChR were determined using the enzyme linked immunosorbent assay technique), CT scan of the thorax and histological diagnosis if thymectomized, and other immunomodulatory agents used, their nature, dosage and duration. The indications for initiating adjunctive treatment with cyclophosphamide were (i) lack of therapeutic response to steroids or other immunosuppressive agents such as azathioprine despite receiving weight appropriate doses for at least 6 months; (ii) presence of significant side effects to steroids; (iii) steroid dependence, defined as recurrence of myasthenic symptoms when the dosage of oral prednisolone was tapered to less than 10–15 mg/day; and/or (iv) inability to afford other steroid sparing agents such as mycophenolate mofetil, intravenous (IV) immunoglobulin, cyclosporine, or rituximab. Cyclophosphamide, 1.0–1.5 g/m2 body surface area, was mixed in 500 ml of normal saline and infused in divided IV doses over 4 to 5 days. The dose was based on our experience in treating other autoimmune diseases like polymyositis and dermatomyositis [15]. The calculated dose was given over 4 to 5 days in order to reduce the side effects and enhance patient tolerance. Co-prescriptions included IV ondansetron (8 mg thrice a day) to reduce the emetic side effects and IV sodium-2-mercaptoethane sulfonate (MESNA; 100 mg at 0, 1 and 8 hours after each dose of IV cyclophosphamide) to decrease the risk of hemorrhagic cystitis. Adequate fluid intake and frequent voiding was encouraged to minimize the risk of hemorrhagic cystitis. IV pulses of cyclophosphamide were thus given once a month for 6 months with subsequent pulses administered once every 3 months depending on the response, tolerability, and adherence to follow-up. The patients
were assessed regularly at the time of administration of each pulse cyclophosphamide for the presence of myasthenic symptoms and signs. The pulse was delayed in the event of cytopenia and/or presence of active infection until their resolution. The response to cyclophosphamide was assessed based on the following parameters: (i) change in clinical status based on the MGFA grade; (ii) change in the requirement of acetylcholinesterase inhibitors; and (iii) change in the doses of steroids or other immunomodulators. The outcome data of 12 patients who completed at least six pulses of IV cyclophosphamide were included for the analysis of cyclophosphamide efficacy. In addition, the adverse effects of cyclophosphamide on the bone marrow, liver, lung, bladder and heart, secondary malignancy, alopecia, and vomiting were also noted, wherever the information was available. These data was incorporated into a Microsoft Excel spreadsheet for analysis (Microsoft Corp., Redmond, WA, USA). 3. Results The clinical features at baseline at the time of initiating treatment with cyclophosphamide are depicted in Table 1. Fifteen episodes of myasthenic crisis necessitating mechanical ventilation were documented in nine patients; in addition, nine episodes of severe bulbar muscle weakness requiring acute symptomatic management with plasma exchange were noted in seven patients prior to cyclophosphamide therapy. Twelve patients completed at least six pulses of IV cyclophosphamide therapy (Table 2). The total number of pulses given ranged from six to 12. Of these, one patient received IV cyclo-
Table 1 Baseline demographic and clinical profile of patients with myasthenia gravis (n = 22) Parameters
Values
Male: Female Mean age at cyclophosphamide initiation Mean duration of MG at time of cyclophosphamide
17: 5 41.05 years (SD 14.7) 80.45 months (SD 99.1) (range 1–317 months)
AChR antibody status Positive Negative Not available
16 4 2
Treatment prior to cyclophosphamide Thymectomy Steroids Azathioprine Methotrexate Mycophenolate mofetil
15 18 9 2 1
MGFA grade prior to cyclophosphamide I II A II B III A III B IV A IV B V
0 5 2 1 4 1 4 5
Other co-existing autoimmune disorders MCTD Thyroid disorder
1 2
Thymus histology Thymoma Thymic carcinoma Thymolipoma Thymic hyperplasia Involuting thymus Normal thymus Data unavailable
3 2 1 3 4 1 1
AChR = anti-acetylcholine receptor, MCTD = mixed connective tissue disorder, MG = myasthenia gravis, MGFA = Myasthenia Gravis Foundation of America, SD = standard deviation.
1911
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914 Table 2 Patient response to intravenous pulse cyclophosphamide (n = 12) Duration AChR Thymectomy Immunomodulators MGFA Number of crisis pre Number of pulses Patient Age at tried grade at cyclophosphamide of Ab cyclophosphamide/ of MG, cyclophosphamide baseline (requiring months status Sex intubation)
Duration of Follow- Time to remission, remission, up months duration, months months
1 2 3 4 5
23/M 55/M 23/M 29/M 75/M
144 120 6 12 6
6 7 8 9 10 11
31/M 44/F 39/M 59/M 34/M 37/M
28 17 51 8 273 168
12
27/F
288
N Y Y Y N
P, Mtx P, A, Mtx P, A P, A None
II A II B III B III B III B
0 0 1 3 0
12 10 10 9 6
36 20 99 19 43
3 5 4 2 4
+ + + NA +
Y Y Y Y Y Y
P, A P, MMF P, A P None P, A
III A II B III B V IV A II A
1 1 0 1 0 0
8 8 6* 6 10 11
39 24 50 19 116 119
2 5 6 1 4 –
+
Y
P, A
II A
0
9
108
–
+ + + +
26 12 13 18 Sustained remission at 3 years 26 18 39 12 19 Did not attain complete remission Did not attain complete remission
A = azathioprine, AChR Ab = anti-acetylcholine receptor antibody, F = female, M = male, MG = myasthenia gravis, MGFA = Myasthenia Gravis Foundation of America, MMF = mycophenolate mofetil, Mtx = methotrexate, N = no, NA = data not available, P = prednisolone, Y = yes, + = positive, = negative. * Cyclophosphamide was given as a part of combination chemotherapy with cisplatin and adriamycin for thymoma.
phosphamide as a part of combination chemotherapy with cisplatin and doxorubicin for thymoma. All patients had a minimum followup period of 1 year (range 19–119 months; mean 57.67 months, standard deviation 40.5 months). Ten patients were taking concomitant immunomodulatory agents at the initiation of pulse cyclophosphamide, comprising prednisolone (n = 8), azathioprine (n = 4), methotrexate (n = 2) and mycophenolate mofetil (n = 1). All 12 patients improved symptomatically, with reduction in the requirement of oral pyridostigmine. At 6 months, 10 patients were asymptomatic, while two patients improved in MGFA grade and had persisting ocular symptoms only (MGFA grade I). Four patients were able to discontinue their current immunomodulating agents (methotrexate in two patients, azathioprine in one, mycophenolate mofetil in one), and in three patients the dosages could be reduced (oral prednisolone in all three). However at 1 year only seven patients maintained their asymptomatic status; of these seven patients five had discontinued pyridostigmine. At 2 years, only three out of 10 patients continued to be asymptomatic. As the duration of follow-up increased up to a maximum of 119 months, 11 out of 12 patients had relapsed necessitating the introduction of alternative immunomodulating agents (Fig. 1). The average time to remission after initiation of IV pulse cyclophosphamide was 3.6 ± 1.6 months (range 1–6 months), while the mean duration of remission was 20.3 ± 8.8 months (range 12–39 months; median 18 months). One patient received six pulses of cyclophosphamide and achieved ‘‘complete stable remission’’ as defined by the MGFA Task Force; unfortunately he developed carcinoma of the glottis 3 years after discontinuing cyclophosphamide (see side effects below). In nine patients, intravenous pulse cyclophosphamide therapy was given for less than 6 months. The reasons for discontinuation of therapy included (i) lost to follow-up after receiving one to three pulses (n = 3), (ii) significant adverse effects (n = 3), (iii) patient non-compliance and irregular follow-up (n = 2), and (iv) sudden unexplained death at home prior to the fourth pulse of cyclophosphamide (n = 1). Of the patients with irregular follow-up, one died 4 years after the interruption of cyclophosphamide therapy due to myasthenic crisis and pseudomonal sepsis. One patient received oral cyclophosphamide. This 35-year-old man presented with generalized MG of 10 years duration and lack
of remission with prednisolone (MGFA grade IVB). He received one pulse of IV cyclophosphamide followed by oral cyclophosphamide. His co-prescriptions included pyridostigmine (240 mg/day) and prednisolone (40 mg/day). He entered remission after 6 months of cyclophosphamide therapy, however his existing regime of pyridostigmine and prednisolone could not be discontinued. After 1 year of oral cyclophosphamide therapy, he suffered a relapse of his myasthenic symptoms (MGFA grade I). Cyclophosphamide was withdrawn and he underwent thymectomy followed by immunomodulation with azathioprine. 3.1. Adverse events Three patients had severe side effects necessitating premature interruption of cyclophosphamide therapy. They included severe vomiting and anemia (n = 1) following the first pulse; pancytopenia, sepsis and multiorgan dysfunction (n = 1) after the first pulse requiring a prolonged intensive care unit stay (this patient was subsequently lost to follow-up); and congestive cardiac failure (n = 1) after three cyclophosphamide pulses (further pulses were suspended). On three occasions, the development of significant side effects necessitated the adjournment of pulse cyclophosphamide therapy until their resolution. These side effects were bicytopenia, diarrhea and abdominal cramps (n = 1), respiratory tract infection (n = 1), and cutaneous abscess (n = 1). In some instances, the adverse reactions could not be conclusively attributed to cyclophosphamide, such as leucopenia (n = 1) which resolved spontaneously when the co-prescribed azathioprine was withdrawn; painful sensory neuropathy (n = 1) following combination chemotherapy with cisplatin and adriamycin; hepatitis (n = 1) 2 months following the ninth pulse of cyclophosphamide in a patient who received sodium valproate concomitantly; tuberculous lymphadenitis (n = 1) in a patient who underwent thymectomy 6 months after discontinuing cyclophosphamide and was found to have tuberculous lymphadenitis on histopathology, and who was receiving methotrexate and oral steroids concomitantly; and one patient, as mentioned earlier, who died of unknown causes prior to the fourth pulse of cyclophosphamide. In addition one patient each was noted to have delayed complications in the form of carcinoma of the glottis and
1912
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914
Fig. 1. Clinical course of patients who received six pulses of cyclophosphamide (x axis = duration of follow up, y axis = Myasthenia Gravis Foundation of America stage). All patients showed significant improvement within 6 months of treatment initiation. Only Patient 5 maintained sustained remission after 3 years. No remission was achieved in Patient 11 or 12. A = azathioprine, CP = cyclophosphamide, MMF = mycophenolate mofetil, dosages in mg, MP = monthly pulse methyl prednisolone, Mtx = methotrexate, P = prednisolone, Py = pyridostigmine.
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914 Table 3 Adverse events noted in 11 patients during intravenous pulse cyclophosphamide therapy Adverse event
Number
Hematological Anemia Pancytopenia Leucopenia Thrombocytopenia
1 2 2 1
Renal Azotemia Renal calculi
2 1
Infection Lower respiratory tract infection Mucocutaneous (including herpes, abscess, fungal infection) Tuberculous lymphadenitisa Knee effusion Acute cholecystitis with perforation Urinary tract infection Fever
5 5 1 1 1 1 1
Cardiac Congestive cardiac failure, hypokinetic anteroseptal wall Sudden unexplained death Left ventricle diastolic dysfunction
1 1 1
Gastrointestinal Emesis Hiatus hernia Abdominal cramps Diarrhea Reflux esophagitis Duodenal ulcers Hepatitis
4 1 2 2 1 1 1
Neurological Distal paraesthesia
1
Malignancy Carcinoma glottisb
1
Other Hair loss Amenorrhoea
2 1
a Detected during histopathological examination of thymectomized specimen. The patient had received cyclophosphamide before thymectomy. b No history of smoking or alcohol consumption.
left ventricular diastolic dysfunction; both complications were noted 2 years after the interruption of cyclophosphamide. Surprisingly, none of the subjects developed bladder-related adverse events in the form of hemorrhagic cystitis; this can be attributed to the routine use of MESNA combined with adequate hydration (Table 3).
4. Discussion MG is a well characterized autoimmune disorder of the neuromuscular junction. The treatment of myasthenia is based on the concepts of pathophysiology and immunology [16,17]. The aim of therapy is to nullify the autoimmune response, thereby providing long-term remission. The response to conventional immunosuppressive agents such as prednisolone, azathioprine, methotrexate, mycophenolate mofetil, plasmapheresis and IV immunoglobulin is not uniform. A proportion of patients may develop intolerable or dose-limiting side effects or have systemic co-morbidities that contraindicate their use. In this study, we retrospectively analyzed the efficacy and tolerability of cyclophosphamide in generalized MG. The clinical course of MG is rather protracted and is marked by fluctuations and intermittent remissions. In a resource-poor setting like India, the cost of long-term immunosuppressive treatment can be prohibitively high. Our center caters primarily to low and middle income patients. Being a state funded institute, it pro-
1913
vides several drugs such as pyridostigmine, azathioprine, oral and IV steroids, and thymectomy and intensive care unit facilities for patients in myasthenic crisis free of cost or at highly subsidized rates. IV cyclophosphamide pulse therapy was chosen for immune therapy in MG as it is inexpensive, has been shown to be safe and effective in inducing remission in refractory MG [5,12] and could be provided free of cost to a large number of poor patients at our center. All patients who completed 6 months of cyclophosphamide therapy improved with a variable duration of remission. In seven out of 12 patients, their pre-existing immunomodulating agents could be reduced or discontinued initially. The role of oral as well as IV pulse cyclophosphamide in the management of both seropositive and seronegative MG has been evaluated in a small number of studies and isolated case reports [3,5,11,13,16]. A randomized, double-blind trial compared the efficacy of IV pulse cyclophosphamide with placebo in seropositive severe generalized MG. Cyclophosphamide therapy was associated with statistically significant improvement in muscle strength, particularly the ocular, masticatory and bulbar muscles [5]. There is no uniformity in the dose and route of administration of cyclophosphamide in MG. As MG is an uncommon disorder with a heterogeneous and fluctuating clinical course, a head to head comparison of various treatment protocols is difficult to carry out. The treatment protocols used in MG have been extrapolated from studies conducted in other autoimmune disorders. Various dosage schedules have been used ranging from a low dose of 2–6 mg/kg to high dose of greater than 1600 mg/m2 body surface area [18,19]. In lupus nephritis, it has been demonstrated that IV low dose cyclophosphamide is as effective as high dose cyclophosphamide, with the former regimen having fewer associated side effects [4]. Likewise, remission rates have been shown to be identical with IV pulse cyclophosphamide as well as daily oral cyclophosphamide in anti-neutrophil cytoplasmic antibody associated vasculitis, with the cumulative dosage and consequent side effects being lower with IV cyclophosphamide [20–22]. Relapses were however more common in patients treated with IV cyclophosphamide [21]. The optimal dosage and duration of cyclophosphamide therapy in various autoimmune disorders remains unclear. In the current study, only one patient received oral cyclophosphamide, and 12 patients completed the initial six pulses of monthly cyclophosphamide therapy, of whom nine received additional maintenance pulses every 3 months (up to a maximum of 12 pulses). Due to the small number of patients it was not possible to derive conclusions regarding the optimal route and duration of cyclophosphamide therapy in the current study. A favourable response to high dose IV cyclophosphamide (50 mg/kg/day for 4 days) has been demonstrated in refractory MG [3,13]. High levels of aldehyde dehydrogenase expressed by the hematopoietic precursor stem cells confer an inherent resistance to cyclophosphamide, thus permitting their survival and repopulation of the immune system by autologous hematopoietic stem cells [23]. This was the basis of ‘‘rebooting’’ the immune system with high dose cyclophosphamide therapy. Besides this, the total cumulative dose with high dose cyclophosphamide is far less compared to long-term treatment with low dose cyclophosphamide, thus avoiding certain adverse effects of long-term cyclophosphamide therapy. In the current study, rebooting the immune system with high dose cyclophosphamide therapy was not attempted because of the lack of facilities in our institute for the care of neutropenic patients. The main strength of this study lies in the long duration of follow-up. Although a favourable response to cyclophosphamide therapy was noted in all patients in the current study within 6 months of initiation, the improvement was not sustained. Only one patient achieved complete stable remission as defined by the
1914
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914
MGFA post-intervention [14], while the rest relapsed after varying intervals and had to be treated with other immune-suppressive agents. Drachman et al. failed to demonstrate sustained or permanent remission after rebooting the immune system with high dose cyclophosphamide, reporting ‘‘the immune system is rebooted but not reformatted’’ [12]. This not only underscores the importance of long-term follow-up, but also the need for developing newer agents with a potential for permanent or long-term remission in MG. Until such time, it may be prudent to use a steroid sparing agent like azathioprine at the end of cyclophosphamide remission induction with the intent of maintaining remission. The adverse effects of cyclophosphamide on the hematopoietic, cardiopulmonary, gastrointestinal and urogenital systems as well as its propensity to cause secondary tumors have been recognized in various studies [19,24–27]. Administration of cyclophosphamide in MG and other autoimmune disorders is considered to be safe and well tolerated [5,12,13,28]. In particular, high dose cyclophosphamide, by virtue of its lower cumulative dose, is believed to be associated with fewer long-term side effects [12]. In the current study, cyclophosphamide had to be suspended or adjourned in nearly one-third (7/22) of the cohort due to adverse events. The risk of secondary malignancy following cyclophosphamide therapy is recognized, with leukemia, lymphoma and bladder cancer being the most common conditions [19,28]. In the present series, one patient developed carcinoma of the glottis, which is a rare site for secondary malignancy. Some of the patients were co-prescribed other immunosuppressants or developed co-morbid illnesses such as diabetes and hypertension, which might have contributed to the occurrence of adverse events. The limitations of this study include its retrospective nature, small cohort size, variable duration and number of cyclophosphamide pulses, non-uniform follow-up, and lack of randomization and blinding. IV pulse cyclophosphamide therapy is useful, cost-effective treatment for MG but the therapeutic benefits in terms of remission are not sustained and patients often develop adverse events. The risk-benefit ratio must be carefully considered before its use and monitoring for adverse events with prevention of anticipated adverse events wherever possible is strongly suggested.
[5]
[6]
[7]
[8]
[9]
[10]
[11] [12]
[13]
[14]
[15]
[16]
[17] [18]
[19]
[20] [21]
[22]
Conflicts of Interest/Disclosures [23]
The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
[24] [25]
References [1] Brodsky RA, Sensenbrenner LL, Jones RJ. Complete remission in severe aplastic anaemia after high-dose cyclophosphamide without bone marrow transplantation. Blood 1996;87:491–4. [2] Brodsky RA, Jones RJ. High-dose cyclophosphamide in aplastic anemia. Lancet 2001;357:1128–9. [3] Drachman DB, Jones RJ, Brodsky RA. Treatment of refractory myasthenia: ‘rebooting’ with a high-dose cyclophosphamide. Ann Neurol 2003;53:29–34. [4] Houssiau FA, Vasconcelos C, D’Cruz D, et al. Immunosuppressive therapy in lupus nephritis: the Euro-Lupus Nephritis Trial, a randomized trial of low-dose
[26]
[27]
[28]
versus high-dose intravenous cyclophosphamide. Arthritis Rheum 2002;46: 2121–31. De Feo LG, Schottlender J, Martelli NA, et al. Use of intravenous pulsed cyclophosphamide in severe, generalized myasthenia gravis. Muscle Nerve 2002;26:31–6. Palace J, Newsom-Davis J, Lecky B. A randomized double-blind trial of prednisolone alone or with azathioprine in myasthenia gravis. Myasthenia Gravis Study Group. Neurology 1998;50:1778–83. Hehir MK, Burns TM, Alpers J, et al. Mycophenolate mofetil in AChR-antibody positive myasthenia gravis: outcomes in 102 patients. Muscle Nerve 2010;41: 593–8. Pestronk A, Drachman DB, Adams RN. Treatment of ongoing experimental myasthenia gravis with short term high dose cyclophosphamide. Muscle Nerve 1982;5:79–84. Toyka KV, Drachman DB, Griffin DE, et al. Myasthenia gravis. Study of humoral immune mechanisms by passive transfer to mice. N Engl J Med 1977;296: 125–31. Flachenecker P, Taleghani BM, Gold R, et al. Treatment of severe myasthenia gravis with protein A immunoadsorption and cyclophosphamide. Transfus Sci 1998;19:43–6. Perez MC, Buot WL, Mercado-Danguilan C, et al. Stable remissions in myasthenia gravis. Neurology 1981;31:32–7. Drachman DB, Adams RN, Hu R, et al. Rebooting the immune system with high-dose cyclophosphamide for treatment of refractory myasthenia gravis. Ann N Y Acad Sci 2008;1132:305–14. Gladstone DE, Brannagan TH 3rd, Schwartzman RJ, et al. High dose cyclophosphamide for severe refractory myasthenia gravis. J Neurol Neurosurg Psychiatry 2004;75:789–91. Jaretzki A 3rd, Barohn RJ, Ernstoff RM, et al. Myasthenia gravis: recommendations for clinical research standards. Task Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of America. Neurology 2000;55:16–23. Nagappa M, Taly AB, Sinha S, et al. Efficacy and limitations of pulse cyclophosphamide therapy in polymyositis and dermatomyositis. J Clin Neuromuscul Dis 2013;14:161–8. Lindstrom JM, Seybold ME, Lennon VA, et al. Antibody to acetylcholine receptor in myasthenia gravis. Prevalence, clinical correlates and diagnostic value. Neurology 1976;26:1054–9. Vincent A. Unraveling the pathogenesis of myasthenia gravis. Nat Rev Immunol 2002;2:797–804. Lin PT, Martin BA, Weinacker AB, et al. High-dose cyclophosphamide in refractory myasthenia gravis with MuSK antibodies. Muscle Nerve 2006;33:433–5. Brodsky RA, Petri M, Smith BD, et al. Immunoablative high-dose cyclophosphamide without stem-cell rescue for refractory, severe autoimmune disease. Ann Intern Med 1998;129:1031–5. Langford CA. Complications of cyclophosphamide therapy. Eur Arch Otorhinolaryngol 1997;254:65–72. de Groot K, Harper L, Jayne DR, et al. Pulse versus daily oral cyclophosphamide for induction of remission in antineutrophil cytoplasmic antibody-associated vasculitis: a randomized trial. Ann Intern Med 2009;150: 670–80. Harper L, Morgan MD, Walsh M, et al. Pulse versus daily oral cyclophosphamide for induction of remission in ANCA-associated vasculitis: long-term follow-up. Ann Rheum Dis 2012; 71: 955–60. Jones RJ, Barber JP, Vala MS, et al. Assessment of aldehyde dehydrogenase in viable cells. Blood 1995;85:2742–6. Bradley JD, Brandt KD, Katz BP. Infectious complications of cyclophosphamide treatment for vasculitis. Arthritis Rheum 1989;32:45–53. Opastirakul S, Chartapisak W. Infection in children with lupus nephritis receiving pulse and oral cyclophosphamide therapy. Pediatr Nephrol 2005;20: 1750–5. Pryor BD, Bologna SG, Kahl LE. Risk factors for serious infection during treatment with cyclophosphamide and high-dose corticosteroids for systemic lupus erythematosus. Arthritis Rheum 1996;39:1475–82. Good JL, Chehrenama M, Mayer RF, et al. Pulse cyclophosphamide therapy in chronic inflammatory demyelinating polyneuropathy. Neurology 1998;51: 1735–8. Travis LB, Curtis RE, Glimelius B, et al. Bladder and kidney cancer following cyclophosphamide therapy for non-Hodgkin’s lymphoma. J Natl Cancer Inst 1995;87:524–30.
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Study
Long-term efficacy and limitations of cyclophosphamide in myasthenia gravis M. Nagappa a, M. Netravathi a, A.B. Taly a,⇑, S. Sinha a, P.S. Bindu a, A. Mahadevan b a b
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore, Karnataka 560 029, India Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
a r t i c l e
i n f o
Article history: Received 17 September 2013 Accepted 5 March 2014
Keywords: Cyclophosphamide Immune therapy Myasthenia gravis
a b s t r a c t Myasthenia gravis (MG) is a chronic autoimmune disorder with a fluctuating clinical course. The aim of immunotherapy is to bring about long-term remission. We evaluated the safety and efficacy of cyclophosphamide in generalized MG. We also highlight the limitations of cyclophosphamide therapy in inducing long-term remission. Data from 22 patients with generalized MG who received cyclophosphamide therapy were analyzed in terms of its safety and outcome. Twelve patients completed at least six pulses of intravenous cyclophosphamide therapy, and all improved symptomatically at 6 months. At 1 year, only seven patients reported sustained benefit and five had discontinued oral pyridostigmine. During a follow-up period of 56.67 months, all but one patient relapsed and required alternative immunomodulatory therapy. The average time to remission after the initiation of intravenous pulse cyclophosphamide (n = 12) was 3.6 months (standard deviation [SD] 1.6 months, range 1–6 months), while the mean duration of remission was 20.3 months (SD 8.8 months, range 12–39 months). Forty-six adverse events were documented in 11 patients over 127 cyclophosphamide pulses. Most of the adverse events were managed symptomatically. In four patients, cyclophosphamide had to be discontinued due to adverse events. Intravenous pulse cyclophosphamide is effective in the management of MG; however remission may be short, necessitating long-term follow-up and alternative immunomodulation. Careful monitoring for adverse events should be mandatory. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Cyclophosphamide is a cell-cycle non-specific anti-proliferative agent that, following hepatic biotransformation to active metabolites, exerts its cytotoxic action primarily by covalent cross-linking of nucleic acids, resulting in unpaired replication of DNA and damage to the DNA structure. Initially developed as a broad spectrum anti-neoplastic agent, cyclophosphamide also has established efficacy and tolerability in a variety of non-neoplastic immune mediated diseases such as systemic lupus erythematosus, rheumatoid arthritis, aplastic anemia, pemphigus, autoimmune neuropathies, and Wegener’s granulomatosis [1–4]. Myasthenia gravis (MG) is a prototype autoimmune disorder characterized by auto-antibody production against the neuromuscular junction. Apart from thymectomy and symptomatic treatment with cholinesterase inhibitors, the mainstay of MG treatment consists of immunosuppression. Steroids are the most commonly used immune-suppressive agents, but are sometimes ⇑ Corresponding author. Tel.: +91 80 2699 5150; fax: +91 80 2656 4830. E-mail address: [email protected] (A.B. Taly). http://dx.doi.org/10.1016/j.jocn.2014.03.019 0967-5868/Ó 2014 Elsevier Ltd. All rights reserved.
associated with significant side effects and poor therapeutic response. Various alternative agents in MG include azathioprine, methotrexate, mycophenolate mofetil, rituximab, tacrolimus and cyclosporine as well as cyclophosphamide. There is a limited range of therapeutic options for ‘‘difficult-to-treat’’ or ‘‘refractory’’ MG, and cyclophosphamide is one of the effective therapies that has been neglected in the literature. It is inexpensive compared to other immunosuppressive agents like rituximab and is widely available. Additionally, it has the advantage of a rapid onset of action compared to azathioprine and mycophenolate mofetil [5–7], and thus lends itself to use in elderly patients, and patients with severe MG or respiratory muscle weakness requiring mechanical ventilation. The efficacy of cyclophosphamide was initially demonstrated in animal models of experimental autoimmune MG [8]. Interestingly, cyclophosphamide has been also shown to induce tolerance to human immunoglobulin in passive transfer models of MG [9]. Subsequent studies have demonstrated that cyclophosphamide is safe and effective in inducing durable remission in MG [5,10–13]. However, to our knowledge only one study has systematically evaluated the long-term outcome of cyclophosphamide therapy in MG [12]. The aim of this study was
1910
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914
to evaluate the short and long-term efficacy and safety of cyclophosphamide in generalized MG.
2. Materials and methods Data from 22 patients with generalized MG who received cyclophosphamide therapy and were followed up at a single neurology unit from 1997 to 2012 at the National Institute of Mental Health and Neurosciences, Bangalore (a university teaching hospital and tertiary care referral centre for neurological and neuropsychiatric patients in south India) were retrospectively analysed. The diagnosis of MG was established by the presence of fluctuating and fatigable weakness of voluntary muscles particularly involving the oculomotor and bulbar muscles and confirmed by (i) electrophysiological testing demonstrating decremental response on supramaximal 3 Hz repetitive nerve stimulation, defined as more than 10% reduction in the amplitude of the negative peak of the compound muscle action potential from the first to the fourth response; (ii) pharmacological testing with neostigmine injection showing unequivocal improvement in muscle strength; or (iii) serological testing demonstrating the presence of antiacetylcholine receptor antibody (AChR Ab). Testing for antibodies to muscle specific tyrosine kinase was not available. The presence of active MG or lack of remission was defined as the presence of any of the following with or without oculomotor involvement in the form of diplopia and ptosis: (i) bulbar involvement (nasal twang, nasal regurgitation, choking or cough upon swallowing, necessitating tube feeding); (ii) respiratory difficulty necessitating mechanical ventilation; or (iii) fatigable limb weakness. The clinical status was assessed using the Myasthenia Gravis Foundation of America (MGFA) Task Force guidelines [14]. The parameters assessed at baseline prior to the initiation of cyclophosphamide therapy included demographic variables of age and sex, clinical features of MGFA grade, duration of MG, number of myasthenic crises, coexisting autoimmune disorders, AChR Ab status (binding antibodies to AChR were determined using the enzyme linked immunosorbent assay technique), CT scan of the thorax and histological diagnosis if thymectomized, and other immunomodulatory agents used, their nature, dosage and duration. The indications for initiating adjunctive treatment with cyclophosphamide were (i) lack of therapeutic response to steroids or other immunosuppressive agents such as azathioprine despite receiving weight appropriate doses for at least 6 months; (ii) presence of significant side effects to steroids; (iii) steroid dependence, defined as recurrence of myasthenic symptoms when the dosage of oral prednisolone was tapered to less than 10–15 mg/day; and/or (iv) inability to afford other steroid sparing agents such as mycophenolate mofetil, intravenous (IV) immunoglobulin, cyclosporine, or rituximab. Cyclophosphamide, 1.0–1.5 g/m2 body surface area, was mixed in 500 ml of normal saline and infused in divided IV doses over 4 to 5 days. The dose was based on our experience in treating other autoimmune diseases like polymyositis and dermatomyositis [15]. The calculated dose was given over 4 to 5 days in order to reduce the side effects and enhance patient tolerance. Co-prescriptions included IV ondansetron (8 mg thrice a day) to reduce the emetic side effects and IV sodium-2-mercaptoethane sulfonate (MESNA; 100 mg at 0, 1 and 8 hours after each dose of IV cyclophosphamide) to decrease the risk of hemorrhagic cystitis. Adequate fluid intake and frequent voiding was encouraged to minimize the risk of hemorrhagic cystitis. IV pulses of cyclophosphamide were thus given once a month for 6 months with subsequent pulses administered once every 3 months depending on the response, tolerability, and adherence to follow-up. The patients
were assessed regularly at the time of administration of each pulse cyclophosphamide for the presence of myasthenic symptoms and signs. The pulse was delayed in the event of cytopenia and/or presence of active infection until their resolution. The response to cyclophosphamide was assessed based on the following parameters: (i) change in clinical status based on the MGFA grade; (ii) change in the requirement of acetylcholinesterase inhibitors; and (iii) change in the doses of steroids or other immunomodulators. The outcome data of 12 patients who completed at least six pulses of IV cyclophosphamide were included for the analysis of cyclophosphamide efficacy. In addition, the adverse effects of cyclophosphamide on the bone marrow, liver, lung, bladder and heart, secondary malignancy, alopecia, and vomiting were also noted, wherever the information was available. These data was incorporated into a Microsoft Excel spreadsheet for analysis (Microsoft Corp., Redmond, WA, USA). 3. Results The clinical features at baseline at the time of initiating treatment with cyclophosphamide are depicted in Table 1. Fifteen episodes of myasthenic crisis necessitating mechanical ventilation were documented in nine patients; in addition, nine episodes of severe bulbar muscle weakness requiring acute symptomatic management with plasma exchange were noted in seven patients prior to cyclophosphamide therapy. Twelve patients completed at least six pulses of IV cyclophosphamide therapy (Table 2). The total number of pulses given ranged from six to 12. Of these, one patient received IV cyclo-
Table 1 Baseline demographic and clinical profile of patients with myasthenia gravis (n = 22) Parameters
Values
Male: Female Mean age at cyclophosphamide initiation Mean duration of MG at time of cyclophosphamide
17: 5 41.05 years (SD 14.7) 80.45 months (SD 99.1) (range 1–317 months)
AChR antibody status Positive Negative Not available
16 4 2
Treatment prior to cyclophosphamide Thymectomy Steroids Azathioprine Methotrexate Mycophenolate mofetil
15 18 9 2 1
MGFA grade prior to cyclophosphamide I II A II B III A III B IV A IV B V
0 5 2 1 4 1 4 5
Other co-existing autoimmune disorders MCTD Thyroid disorder
1 2
Thymus histology Thymoma Thymic carcinoma Thymolipoma Thymic hyperplasia Involuting thymus Normal thymus Data unavailable
3 2 1 3 4 1 1
AChR = anti-acetylcholine receptor, MCTD = mixed connective tissue disorder, MG = myasthenia gravis, MGFA = Myasthenia Gravis Foundation of America, SD = standard deviation.
1911
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914 Table 2 Patient response to intravenous pulse cyclophosphamide (n = 12) Duration AChR Thymectomy Immunomodulators MGFA Number of crisis pre Number of pulses Patient Age at tried grade at cyclophosphamide of Ab cyclophosphamide/ of MG, cyclophosphamide baseline (requiring months status Sex intubation)
Duration of Follow- Time to remission, remission, up months duration, months months
1 2 3 4 5
23/M 55/M 23/M 29/M 75/M
144 120 6 12 6
6 7 8 9 10 11
31/M 44/F 39/M 59/M 34/M 37/M
28 17 51 8 273 168
12
27/F
288
N Y Y Y N
P, Mtx P, A, Mtx P, A P, A None
II A II B III B III B III B
0 0 1 3 0
12 10 10 9 6
36 20 99 19 43
3 5 4 2 4
+ + + NA +
Y Y Y Y Y Y
P, A P, MMF P, A P None P, A
III A II B III B V IV A II A
1 1 0 1 0 0
8 8 6* 6 10 11
39 24 50 19 116 119
2 5 6 1 4 –
+
Y
P, A
II A
0
9
108
–
+ + + +
26 12 13 18 Sustained remission at 3 years 26 18 39 12 19 Did not attain complete remission Did not attain complete remission
A = azathioprine, AChR Ab = anti-acetylcholine receptor antibody, F = female, M = male, MG = myasthenia gravis, MGFA = Myasthenia Gravis Foundation of America, MMF = mycophenolate mofetil, Mtx = methotrexate, N = no, NA = data not available, P = prednisolone, Y = yes, + = positive, = negative. * Cyclophosphamide was given as a part of combination chemotherapy with cisplatin and adriamycin for thymoma.
phosphamide as a part of combination chemotherapy with cisplatin and doxorubicin for thymoma. All patients had a minimum followup period of 1 year (range 19–119 months; mean 57.67 months, standard deviation 40.5 months). Ten patients were taking concomitant immunomodulatory agents at the initiation of pulse cyclophosphamide, comprising prednisolone (n = 8), azathioprine (n = 4), methotrexate (n = 2) and mycophenolate mofetil (n = 1). All 12 patients improved symptomatically, with reduction in the requirement of oral pyridostigmine. At 6 months, 10 patients were asymptomatic, while two patients improved in MGFA grade and had persisting ocular symptoms only (MGFA grade I). Four patients were able to discontinue their current immunomodulating agents (methotrexate in two patients, azathioprine in one, mycophenolate mofetil in one), and in three patients the dosages could be reduced (oral prednisolone in all three). However at 1 year only seven patients maintained their asymptomatic status; of these seven patients five had discontinued pyridostigmine. At 2 years, only three out of 10 patients continued to be asymptomatic. As the duration of follow-up increased up to a maximum of 119 months, 11 out of 12 patients had relapsed necessitating the introduction of alternative immunomodulating agents (Fig. 1). The average time to remission after initiation of IV pulse cyclophosphamide was 3.6 ± 1.6 months (range 1–6 months), while the mean duration of remission was 20.3 ± 8.8 months (range 12–39 months; median 18 months). One patient received six pulses of cyclophosphamide and achieved ‘‘complete stable remission’’ as defined by the MGFA Task Force; unfortunately he developed carcinoma of the glottis 3 years after discontinuing cyclophosphamide (see side effects below). In nine patients, intravenous pulse cyclophosphamide therapy was given for less than 6 months. The reasons for discontinuation of therapy included (i) lost to follow-up after receiving one to three pulses (n = 3), (ii) significant adverse effects (n = 3), (iii) patient non-compliance and irregular follow-up (n = 2), and (iv) sudden unexplained death at home prior to the fourth pulse of cyclophosphamide (n = 1). Of the patients with irregular follow-up, one died 4 years after the interruption of cyclophosphamide therapy due to myasthenic crisis and pseudomonal sepsis. One patient received oral cyclophosphamide. This 35-year-old man presented with generalized MG of 10 years duration and lack
of remission with prednisolone (MGFA grade IVB). He received one pulse of IV cyclophosphamide followed by oral cyclophosphamide. His co-prescriptions included pyridostigmine (240 mg/day) and prednisolone (40 mg/day). He entered remission after 6 months of cyclophosphamide therapy, however his existing regime of pyridostigmine and prednisolone could not be discontinued. After 1 year of oral cyclophosphamide therapy, he suffered a relapse of his myasthenic symptoms (MGFA grade I). Cyclophosphamide was withdrawn and he underwent thymectomy followed by immunomodulation with azathioprine. 3.1. Adverse events Three patients had severe side effects necessitating premature interruption of cyclophosphamide therapy. They included severe vomiting and anemia (n = 1) following the first pulse; pancytopenia, sepsis and multiorgan dysfunction (n = 1) after the first pulse requiring a prolonged intensive care unit stay (this patient was subsequently lost to follow-up); and congestive cardiac failure (n = 1) after three cyclophosphamide pulses (further pulses were suspended). On three occasions, the development of significant side effects necessitated the adjournment of pulse cyclophosphamide therapy until their resolution. These side effects were bicytopenia, diarrhea and abdominal cramps (n = 1), respiratory tract infection (n = 1), and cutaneous abscess (n = 1). In some instances, the adverse reactions could not be conclusively attributed to cyclophosphamide, such as leucopenia (n = 1) which resolved spontaneously when the co-prescribed azathioprine was withdrawn; painful sensory neuropathy (n = 1) following combination chemotherapy with cisplatin and adriamycin; hepatitis (n = 1) 2 months following the ninth pulse of cyclophosphamide in a patient who received sodium valproate concomitantly; tuberculous lymphadenitis (n = 1) in a patient who underwent thymectomy 6 months after discontinuing cyclophosphamide and was found to have tuberculous lymphadenitis on histopathology, and who was receiving methotrexate and oral steroids concomitantly; and one patient, as mentioned earlier, who died of unknown causes prior to the fourth pulse of cyclophosphamide. In addition one patient each was noted to have delayed complications in the form of carcinoma of the glottis and
1912
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914
Fig. 1. Clinical course of patients who received six pulses of cyclophosphamide (x axis = duration of follow up, y axis = Myasthenia Gravis Foundation of America stage). All patients showed significant improvement within 6 months of treatment initiation. Only Patient 5 maintained sustained remission after 3 years. No remission was achieved in Patient 11 or 12. A = azathioprine, CP = cyclophosphamide, MMF = mycophenolate mofetil, dosages in mg, MP = monthly pulse methyl prednisolone, Mtx = methotrexate, P = prednisolone, Py = pyridostigmine.
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914 Table 3 Adverse events noted in 11 patients during intravenous pulse cyclophosphamide therapy Adverse event
Number
Hematological Anemia Pancytopenia Leucopenia Thrombocytopenia
1 2 2 1
Renal Azotemia Renal calculi
2 1
Infection Lower respiratory tract infection Mucocutaneous (including herpes, abscess, fungal infection) Tuberculous lymphadenitisa Knee effusion Acute cholecystitis with perforation Urinary tract infection Fever
5 5 1 1 1 1 1
Cardiac Congestive cardiac failure, hypokinetic anteroseptal wall Sudden unexplained death Left ventricle diastolic dysfunction
1 1 1
Gastrointestinal Emesis Hiatus hernia Abdominal cramps Diarrhea Reflux esophagitis Duodenal ulcers Hepatitis
4 1 2 2 1 1 1
Neurological Distal paraesthesia
1
Malignancy Carcinoma glottisb
1
Other Hair loss Amenorrhoea
2 1
a Detected during histopathological examination of thymectomized specimen. The patient had received cyclophosphamide before thymectomy. b No history of smoking or alcohol consumption.
left ventricular diastolic dysfunction; both complications were noted 2 years after the interruption of cyclophosphamide. Surprisingly, none of the subjects developed bladder-related adverse events in the form of hemorrhagic cystitis; this can be attributed to the routine use of MESNA combined with adequate hydration (Table 3).
4. Discussion MG is a well characterized autoimmune disorder of the neuromuscular junction. The treatment of myasthenia is based on the concepts of pathophysiology and immunology [16,17]. The aim of therapy is to nullify the autoimmune response, thereby providing long-term remission. The response to conventional immunosuppressive agents such as prednisolone, azathioprine, methotrexate, mycophenolate mofetil, plasmapheresis and IV immunoglobulin is not uniform. A proportion of patients may develop intolerable or dose-limiting side effects or have systemic co-morbidities that contraindicate their use. In this study, we retrospectively analyzed the efficacy and tolerability of cyclophosphamide in generalized MG. The clinical course of MG is rather protracted and is marked by fluctuations and intermittent remissions. In a resource-poor setting like India, the cost of long-term immunosuppressive treatment can be prohibitively high. Our center caters primarily to low and middle income patients. Being a state funded institute, it pro-
1913
vides several drugs such as pyridostigmine, azathioprine, oral and IV steroids, and thymectomy and intensive care unit facilities for patients in myasthenic crisis free of cost or at highly subsidized rates. IV cyclophosphamide pulse therapy was chosen for immune therapy in MG as it is inexpensive, has been shown to be safe and effective in inducing remission in refractory MG [5,12] and could be provided free of cost to a large number of poor patients at our center. All patients who completed 6 months of cyclophosphamide therapy improved with a variable duration of remission. In seven out of 12 patients, their pre-existing immunomodulating agents could be reduced or discontinued initially. The role of oral as well as IV pulse cyclophosphamide in the management of both seropositive and seronegative MG has been evaluated in a small number of studies and isolated case reports [3,5,11,13,16]. A randomized, double-blind trial compared the efficacy of IV pulse cyclophosphamide with placebo in seropositive severe generalized MG. Cyclophosphamide therapy was associated with statistically significant improvement in muscle strength, particularly the ocular, masticatory and bulbar muscles [5]. There is no uniformity in the dose and route of administration of cyclophosphamide in MG. As MG is an uncommon disorder with a heterogeneous and fluctuating clinical course, a head to head comparison of various treatment protocols is difficult to carry out. The treatment protocols used in MG have been extrapolated from studies conducted in other autoimmune disorders. Various dosage schedules have been used ranging from a low dose of 2–6 mg/kg to high dose of greater than 1600 mg/m2 body surface area [18,19]. In lupus nephritis, it has been demonstrated that IV low dose cyclophosphamide is as effective as high dose cyclophosphamide, with the former regimen having fewer associated side effects [4]. Likewise, remission rates have been shown to be identical with IV pulse cyclophosphamide as well as daily oral cyclophosphamide in anti-neutrophil cytoplasmic antibody associated vasculitis, with the cumulative dosage and consequent side effects being lower with IV cyclophosphamide [20–22]. Relapses were however more common in patients treated with IV cyclophosphamide [21]. The optimal dosage and duration of cyclophosphamide therapy in various autoimmune disorders remains unclear. In the current study, only one patient received oral cyclophosphamide, and 12 patients completed the initial six pulses of monthly cyclophosphamide therapy, of whom nine received additional maintenance pulses every 3 months (up to a maximum of 12 pulses). Due to the small number of patients it was not possible to derive conclusions regarding the optimal route and duration of cyclophosphamide therapy in the current study. A favourable response to high dose IV cyclophosphamide (50 mg/kg/day for 4 days) has been demonstrated in refractory MG [3,13]. High levels of aldehyde dehydrogenase expressed by the hematopoietic precursor stem cells confer an inherent resistance to cyclophosphamide, thus permitting their survival and repopulation of the immune system by autologous hematopoietic stem cells [23]. This was the basis of ‘‘rebooting’’ the immune system with high dose cyclophosphamide therapy. Besides this, the total cumulative dose with high dose cyclophosphamide is far less compared to long-term treatment with low dose cyclophosphamide, thus avoiding certain adverse effects of long-term cyclophosphamide therapy. In the current study, rebooting the immune system with high dose cyclophosphamide therapy was not attempted because of the lack of facilities in our institute for the care of neutropenic patients. The main strength of this study lies in the long duration of follow-up. Although a favourable response to cyclophosphamide therapy was noted in all patients in the current study within 6 months of initiation, the improvement was not sustained. Only one patient achieved complete stable remission as defined by the
1914
M. Nagappa et al. / Journal of Clinical Neuroscience 21 (2014) 1909–1914
MGFA post-intervention [14], while the rest relapsed after varying intervals and had to be treated with other immune-suppressive agents. Drachman et al. failed to demonstrate sustained or permanent remission after rebooting the immune system with high dose cyclophosphamide, reporting ‘‘the immune system is rebooted but not reformatted’’ [12]. This not only underscores the importance of long-term follow-up, but also the need for developing newer agents with a potential for permanent or long-term remission in MG. Until such time, it may be prudent to use a steroid sparing agent like azathioprine at the end of cyclophosphamide remission induction with the intent of maintaining remission. The adverse effects of cyclophosphamide on the hematopoietic, cardiopulmonary, gastrointestinal and urogenital systems as well as its propensity to cause secondary tumors have been recognized in various studies [19,24–27]. Administration of cyclophosphamide in MG and other autoimmune disorders is considered to be safe and well tolerated [5,12,13,28]. In particular, high dose cyclophosphamide, by virtue of its lower cumulative dose, is believed to be associated with fewer long-term side effects [12]. In the current study, cyclophosphamide had to be suspended or adjourned in nearly one-third (7/22) of the cohort due to adverse events. The risk of secondary malignancy following cyclophosphamide therapy is recognized, with leukemia, lymphoma and bladder cancer being the most common conditions [19,28]. In the present series, one patient developed carcinoma of the glottis, which is a rare site for secondary malignancy. Some of the patients were co-prescribed other immunosuppressants or developed co-morbid illnesses such as diabetes and hypertension, which might have contributed to the occurrence of adverse events. The limitations of this study include its retrospective nature, small cohort size, variable duration and number of cyclophosphamide pulses, non-uniform follow-up, and lack of randomization and blinding. IV pulse cyclophosphamide therapy is useful, cost-effective treatment for MG but the therapeutic benefits in terms of remission are not sustained and patients often develop adverse events. The risk-benefit ratio must be carefully considered before its use and monitoring for adverse events with prevention of anticipated adverse events wherever possible is strongly suggested.
[5]
[6]
[7]
[8]
[9]
[10]
[11] [12]
[13]
[14]
[15]
[16]
[17] [18]
[19]
[20] [21]
[22]
Conflicts of Interest/Disclosures [23]
The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
[24] [25]
References [1] Brodsky RA, Sensenbrenner LL, Jones RJ. Complete remission in severe aplastic anaemia after high-dose cyclophosphamide without bone marrow transplantation. Blood 1996;87:491–4. [2] Brodsky RA, Jones RJ. High-dose cyclophosphamide in aplastic anemia. Lancet 2001;357:1128–9. [3] Drachman DB, Jones RJ, Brodsky RA. Treatment of refractory myasthenia: ‘rebooting’ with a high-dose cyclophosphamide. Ann Neurol 2003;53:29–34. [4] Houssiau FA, Vasconcelos C, D’Cruz D, et al. Immunosuppressive therapy in lupus nephritis: the Euro-Lupus Nephritis Trial, a randomized trial of low-dose
[26]
[27]
[28]
versus high-dose intravenous cyclophosphamide. Arthritis Rheum 2002;46: 2121–31. De Feo LG, Schottlender J, Martelli NA, et al. Use of intravenous pulsed cyclophosphamide in severe, generalized myasthenia gravis. Muscle Nerve 2002;26:31–6. Palace J, Newsom-Davis J, Lecky B. A randomized double-blind trial of prednisolone alone or with azathioprine in myasthenia gravis. Myasthenia Gravis Study Group. Neurology 1998;50:1778–83. Hehir MK, Burns TM, Alpers J, et al. Mycophenolate mofetil in AChR-antibody positive myasthenia gravis: outcomes in 102 patients. Muscle Nerve 2010;41: 593–8. Pestronk A, Drachman DB, Adams RN. Treatment of ongoing experimental myasthenia gravis with short term high dose cyclophosphamide. Muscle Nerve 1982;5:79–84. Toyka KV, Drachman DB, Griffin DE, et al. Myasthenia gravis. Study of humoral immune mechanisms by passive transfer to mice. N Engl J Med 1977;296: 125–31. Flachenecker P, Taleghani BM, Gold R, et al. Treatment of severe myasthenia gravis with protein A immunoadsorption and cyclophosphamide. Transfus Sci 1998;19:43–6. Perez MC, Buot WL, Mercado-Danguilan C, et al. Stable remissions in myasthenia gravis. Neurology 1981;31:32–7. Drachman DB, Adams RN, Hu R, et al. Rebooting the immune system with high-dose cyclophosphamide for treatment of refractory myasthenia gravis. Ann N Y Acad Sci 2008;1132:305–14. Gladstone DE, Brannagan TH 3rd, Schwartzman RJ, et al. High dose cyclophosphamide for severe refractory myasthenia gravis. J Neurol Neurosurg Psychiatry 2004;75:789–91. Jaretzki A 3rd, Barohn RJ, Ernstoff RM, et al. Myasthenia gravis: recommendations for clinical research standards. Task Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of America. Neurology 2000;55:16–23. Nagappa M, Taly AB, Sinha S, et al. Efficacy and limitations of pulse cyclophosphamide therapy in polymyositis and dermatomyositis. J Clin Neuromuscul Dis 2013;14:161–8. Lindstrom JM, Seybold ME, Lennon VA, et al. Antibody to acetylcholine receptor in myasthenia gravis. Prevalence, clinical correlates and diagnostic value. Neurology 1976;26:1054–9. Vincent A. Unraveling the pathogenesis of myasthenia gravis. Nat Rev Immunol 2002;2:797–804. Lin PT, Martin BA, Weinacker AB, et al. High-dose cyclophosphamide in refractory myasthenia gravis with MuSK antibodies. Muscle Nerve 2006;33:433–5. Brodsky RA, Petri M, Smith BD, et al. Immunoablative high-dose cyclophosphamide without stem-cell rescue for refractory, severe autoimmune disease. Ann Intern Med 1998;129:1031–5. Langford CA. Complications of cyclophosphamide therapy. Eur Arch Otorhinolaryngol 1997;254:65–72. de Groot K, Harper L, Jayne DR, et al. Pulse versus daily oral cyclophosphamide for induction of remission in antineutrophil cytoplasmic antibody-associated vasculitis: a randomized trial. Ann Intern Med 2009;150: 670–80. Harper L, Morgan MD, Walsh M, et al. Pulse versus daily oral cyclophosphamide for induction of remission in ANCA-associated vasculitis: long-term follow-up. Ann Rheum Dis 2012; 71: 955–60. Jones RJ, Barber JP, Vala MS, et al. Assessment of aldehyde dehydrogenase in viable cells. Blood 1995;85:2742–6. Bradley JD, Brandt KD, Katz BP. Infectious complications of cyclophosphamide treatment for vasculitis. Arthritis Rheum 1989;32:45–53. Opastirakul S, Chartapisak W. Infection in children with lupus nephritis receiving pulse and oral cyclophosphamide therapy. Pediatr Nephrol 2005;20: 1750–5. Pryor BD, Bologna SG, Kahl LE. Risk factors for serious infection during treatment with cyclophosphamide and high-dose corticosteroids for systemic lupus erythematosus. Arthritis Rheum 1996;39:1475–82. Good JL, Chehrenama M, Mayer RF, et al. Pulse cyclophosphamide therapy in chronic inflammatory demyelinating polyneuropathy. Neurology 1998;51: 1735–8. Travis LB, Curtis RE, Glimelius B, et al. Bladder and kidney cancer following cyclophosphamide therapy for non-Hodgkin’s lymphoma. J Natl Cancer Inst 1995;87:524–30.