Cyclophosphamide in refractory MG, page1
Induction IV cyclophosphamide followed by maintenance oral immunosuppression in refractory myasthenia gravis Katherine A. Buzzard1, MBBS PhD, Nicholas J. Meyer2, BSc, Todd A. Hardy1, MBBS PhD, D. Sean Riminton2, MBBS PhD, Stephen W. Reddel1, MBBS PhD. 1
Department of Neurology, Concord Repatriation General Hospital, Concord West, New
South Wales, Australia 2
Department of Immunology, Concord Repatriation General Hospital, Concord West, New
South Wales, Australia
Corresponding Author: Stephen W. Reddel, Department of Neurology, Concord Repatriation General Hospital, 2139, New South Wales, Australia; Ph: +61297676129, Fax: +61292100533, email: [email protected]
Running Title: Cyclophosphamide in refractory MG
th
This paper was presented at the 4 International Conference, Advances in Clinical Neuroimmunology, Krakow, Poland, 27-28 June 2014.
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as an ‘Accepted Article’, doi: 10.1002/mus.24536 This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Induction IV cyclophosphamide followed by maintenance oral immunosuppression in refractory myasthenia gravis Introduction: Myasthenia gravis (MG) can be refractory to conventional immunotherapy. We report on the efficacy and durability of intravenous remission-induction cyclophosphamide (CYC) followed by oral immunosuppression in refractory MG. Methods: We identified 8 patients from our medical records with moderate or severe refractory MG who were treated with 6 cycles of 4-weekly IV-CYC (0.75 g/m2) followed by oral immunosuppression. Results: Six patients improved within 3 months of treatment. Four patients remained in clinical remission (mean follow-up 31 months). Two patients responded partially, and 1 patient relapsed after 11 months. Two patients were non-responders. CYC was well tolerated. Acetylcholine receptor antibody levels remained below pre-treatment levels in patients in clinical remission. The leukocyte nadir was lower in CYC responders. Conclusions: Remission-induction IV-CYC followed by oral immunosuppression is a rapid, effective, and durable treatment for refractory MG. Adding a post-CYC immunosuppressant may account for low relapse rates compared to other published series.
Keywords Myasthenia gravis, refractory, cyclophosphamide, immunosuppression, treatment
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 2 of 25
Page 3 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Introduction Myasthenia gravis (MG) is a chronic autoimmune disease of the neuromuscular junction characterized by fluctuating weakness. In most cases, MG can be treated effectively with symptomatic and immunomodulatory treatments such as pyridostigmine, corticosteroids, azathioprine, mycophenolate, cyclosporine, and methotrexate. A subset of MG patients however, experience progressive, relapsing, and disabling disease despite conventional immune therapies. The disease course in these treatment-refractory patients is often characterized by frequent hospitalization due to severe respiratory or bulbar symptoms requiring “rescue” therapy with plasma exchange (PLEX) and intravenous (IV) immunoglobulin (IVIG). These patients frequently bear the consequences of long-term highdose corticosteroid therapy, including osteoporosis, obesity, and diabetes mellitus, among others. Cyclophosphamide (CYC) has generated interest as an effective second-line agent for treatment of refractory MG. Several groups have shown that high-dose CYC can induce at least short-term disease remission in patients with severe, refractory MG1-5. A limitation of CYC treatment appears to be the duration of benefit; most studies have reported that patients relapse and require further escalation of immunomodulatory therapy. An additional concern is the potential for short- and long-term toxicity with high-dose CYC regimens. The cumulative dose of CYC can be reduced by using protocols based on induction CYC followed by maintenance with a less toxic immunosuppressive agent. These protocols have been used successfully in clinical trials of patients with lupus nephritis, granulomatosis with polyangiitis, and microscopic polyangiitis and have been shown to result in reduced toxicity without compromising efficacy 6,7. We report on the efficacy, durability, and safety of remission-induction pulsed IV CYC followed by maintenance oral immunosuppression in 8 patients with moderate or severe, refractory myasthenia gravis followed for 8-58 months. We demonstrate that this reduced
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
intensity regimen shows efficacy in inducing disease remission and avoids the complication of severe cytopenias. We also suggest that routine administration of maintenance oral immunosuppression may reduce the risk of subsequent relapse. Methods: Eighty-two patients with a diagnosis of MG were identified from a database of patients followed in the Neuroimmunology clinic at Concord Hospital. This clinic focuses on the treatment of patients with moderate to severe neuroimmunological disorders requiring complex therapy. Treatment-refractory MG patients were identified based on resistance, toxicities, or contraindications to conventional immunosuppressive treatments, and/or dependence on PLEX or IVIG according to previous studies 4. Eight patients with treatmentrefractory MG were treated with CYC during the course of their disease. Clinical and demographic data were extracted from the medical records of each patient. Each patient’s worst disease status was rated according to the Myasthenia Gravis Foundation of America (MGFA) classification (Grade I=ocular disease only, Grade II= mild weakness, Grade III=moderate weakness, Grade IV=severe weakness, Grade V = assisted ventilation; the “a” subtype denotes predominantly limb/axial muscles, and the “b” subtype denotes predominantly bulbar/respiratory muscles) 8. Clinical disease severity was also calculated according to the Myasthenia Gravis Composite (MGC) scale, which uses data routinely collected at consultation 9. When the MGC was derived retrospectively from clinical symptoms and examination findings documented in the medical record, the term “estimated MGC” is used to reflect the minimum calculated MGC. Patients gave informed consent for CYC after discussion of the risks and benefits of treatment. Patients underwent an immunosuppression risk management assessment prior to starting treatment (www.immunosuppressionscreen.net, accession date 18th July 2014)10,11. Infusions were given in the outpatient setting unless the MG severity required hospital admission. Each infusion was subject to a satisfactory neutrophil count (>1.5 x109/L) in the 2
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 4 of 25
Page 5 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
weeks prior to each cycle. CYC (0.75 g/m2) was infused via peripheral IV access every 4 weeks for 6 cycles. The maximum dose of CYC was set at 1500 mg per cycle. The dose was reduced to 0.5 g/m2 if the glomerular filtration rate was less than 30% of normal. Smaller individual dose reductions were made if the neutrophil count fell below 1.5 x109/L at the 1014 day nadir. Patients received prophylactic anti-emetics concurrently with granisetron and dexamethasone with each cycle of CYC. Pneumocystis jiroveci pneumonia prophylaxis with Cotrimoxazole was given to all patients during the treatment period and for 1 month after the last course of CYC. One month after completing the 6th cycle of CYC, patients were started on maintenance immunotherapy with mycophenolate, azathioprine, or methotrexate. Acetylcholine receptor (AChR) and muscle-specific tyrosine kinase (MuSK) antibodies were measured by radioimmunoassays following the manufacturer’s instructions (RSR, UK). This study was conducted in accordance with the Declaration of Helsinki with approval by the human research ethics committee of Concord Hospital. Results: Patient characteristics Eight patients received treatment with 6 cycles of 4-weekly IV pulsed CYC (0.75 g/m2) between October 2008 and October 2013 (Table 1). Each patient had a definite diagnosis of MG based on typical clinical symptoms and examination findings, together with confirmatory electrophysiological studies and/or antibodies to AChR (n=6) or MuSK (n=1). One patient was seronegative for AChR, MuSK, and low-density lipoprotein receptor-related protein 4 (Lrp4) antibodies. There were 6 male and 2 women with a mean age of 57 years (range 2976 years). Disease duration at the time of CYC treatment ranged from 4-172 months (median 63 months). Six patients (patients 1, 3, 4, 6, 7, and 8) received CYC in the context of moderate or severe MG (MGFA grade III-IV) despite PLEX and moderate to high-dose prednisone (equivalent to 12.5-50 mg daily) in conjunction with other immunomodulatory therapy (Table 1). Treatment with CYC was initiated during a respiratory crisis in 1 patient
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
(patient 5) who had only a limited response to frequent PLEX and IVIG. The decision to treat one patient (patient 2) with CYC was made based on moderate MG symptoms (MGFA grade IIIb) requiring high dose prednisone, together with extensive medical co-morbidities limiting the use of alternative immunomodulatory therapy. Each patient had experienced MG treatment side effects prior to the initiation of CYC (Table 1). All patients had documented osteopenia or osteoporosis as a likely consequence of prolonged corticosteroid therapy. Clinical response Six patients had dramatic improvement in clinical symptoms and estimated MGC during the 6-month treatment period (Figure 1). The mean time to onset of clinical improvement was 2 months (range 1-3 months) (Table 2). Clinical improvement allowed reduction in prednisone dose during the treatment period in all 6 patients. At last follow-up, 4 patients remained in clinical remission (MGC 0) on maintenance therapy. Three of these patients (patients 1, 2, and 4) were stable on either azathioprine or mycophenolate, having ceased prednisone at month 15, 22, and 9, respectively (Table 2). Patient 1 was temporarily restarted on low dose prednisone (5 mg daily) at 17 months after developing mild proximal weakness, however this was subsequently weaned over 12 months. The fourth patient in clinical remission (patient 5) remains on low dose prednisone (equivalent to 2.5 mg daily) and methotrexate at last followup (15 months). Two patients responded partially to CYC. Patient 3 improved clinically during the treatment period and was able to halve his prednisone dose and cease PLEX. However, he relapsed 11 months after starting CYC, requiring re-escalation of prednisone and short-term PLEX. Patient 7 improved dramatically following CYC treatment, which allowed his prednisone dose to be weaned substantially and PLEX to be withdrawn. He continues to have mild bulbar symptoms and remains on a moderate dose of prednisone, regular pyridostigmine, and mycophenolate. Two patients were considered non-responders to CYC. Prior to CYC, patient 6 (MuSK antibody positive) was PLEX-dependent despite prednisone, azathioprine, and rituximab
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 6 of 25
Page 7 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page7
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
treatment (2x 500 mg given 4 weeks apart) completed 5 months prior to CYC and resulting in transient B-cell depletion (lasting less than 5 months). He deteriorated during the CYC treatment (Figure 1). Later treatment with high dose rituximab (1000mg weekly for 4 weeks) resulted in marked clinical improvement and prolonged peripheral blood B-cell depletion. Patient 8 had transient reduction in his MGC at 3 months, however his symptoms worsened toward the end of the CYC treatment period (Figure 1). He continued to require intensive immunomodulatory therapy with weekly PLEX, moderate doses of prednisone, and regular pyridostigmine and was considered to be a CYC non-responder. Treatment tolerability Treatment with CYC was tolerated well in all patients. Mild subclinical neutropenia was observed in 2 patients prompting a slight dose reduction at the subsequent treatment cycle. Any cytopenias were mild, and no patients required support with blood products or granulocyte colony-stimulating factor (G-CSF). Patient 7 underwent an emergency laparotomy for a bowel perforation secondary to pneumatosis coli after CYC cycle 2. This was felt to be related to high-dose IV methylprednisolone administered shortly beforehand, rather than a complication of CYC. Two patients (patients 5 and 4) were diagnosed with infections during the CYC treatment period; patient 5 was treated for ventilator-acquired pneumonia during the acute myasthenia crisis, while patient 4 developed a minor urinary tract infection. Both patients made a full recovery with no long-term sequelae. There have been no reports of malignancies in the follow-up period to date. Laboratory investigations AChR antibody levels pre- and post-CYC for the 6 seropositive patients showed partial concordance with clinical outcome (supplementary Figure S1, available online). Antibody levels fell initially in 4 patients. At last follow-up, AChR antibody levels remained below pretreatment levels in 3 patients with sustained clinical remission, whereas the antibody level had returned to pre-treatment level within 12 months of CYC in a partial responder. AChR
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
antibody levels remained unchanged or increased in 2 patients; 1 patient was a clinical nonresponder to CYC and the other had initial improvement following CYC but subsequently relapsed. All patients underwent frequent full blood examination to monitor for cytopenias during their CYC treatment period. Four patients developed a peripheral blood leukocyte count nadir below the normal range (supplementary Figure S2, available online). These patients all had at least a partial response to CYC. The 2 patients who were clinical non-responders had the highest leukocyte count nadir, remaining well within the normal range (5.5 x109/L and 6.1 x109/L, normal 4.0-10.0 x109/L). Discussion In this retrospective case series of highly selected patients with moderate or severe refractory MG, we have shown that pulsed IV CYC administered every 4 weeks for 6 cycles followed by conventional oral immunotherapy was associated with marked clinical improvement in 6 of 8 patients (75%). Improvement allowed oral corticosteroids to be tapered during the treatment period in all 6 patients. Corticosteroid reduction was of particular relevance in this patient cohort, since all 8 patients had experienced complications from long-term steroid therapy. Four patients (50%) achieved clinical remission while on maintenance therapy, 3 of whom were also able to completely withdraw prednisone. Our results support the findings of other published studies that have shown the efficacy of CYC in patients with severe, refractory MG 1,2,3,4,5,12. Disappointingly, many of these studies have shown that the benefits of CYC are often short-lived, and the majority of patients have relapsed. One of the largest published series by Drachman et al (2008) reported 11 of 12 patients with severe, refractory MG improved after high-dose CYC, however only 2 patients had a durable response without the need for subsequent treatment escalation 4.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 8 of 25
Page 9 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page9
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The precise mechanism of action of CYC in the treatment of MG remains unclear. At least some of its therapeutic action may relate to the capacity of CYC to induce lymphocyte apoptosis, resulting in a quantitative reduction in the activated lymphocyte populations that are responsible for driving new plasmablast and plasma cell formation. In turn, this would reduce the production of pathogenic autoantibodies. We hypothesized that introducing a maintenance anti-proliferative immunosuppressant following remission-induction CYC could prevent re-emergence of the pathogenic activated lymphocytes, thereby prolonging clinical remission. We routinely treated patients with a conventional oral immunosuppressant after completion of 6 cycles of CYC. Of the 6 patients who responded clinically to CYC, only 1 had subsequently relapsed at last follow-up. Although the patient numbers are small, the low relapse rate to date supports the hypothesis that routine addition of maintenance oral immunosuppression may prolong the clinical response to CYC. Many of the published studies showing the benefit of CYC in the treatment of severe, refractory MG have employed high dose regimens or prolonged treatment courses, resulting in higher cumulative doses of CYC 1,4,5. CYC carries a risk of serious adverse effects. In the short-term, bone marrow suppression and severe leukopenia put patients at risk of septicemia and life-threatening infections. High-dose regimens typically result in severe cytopenias requiring blood products and G-CSF. In the study by Drachman et al (2008) which utilized high-dose CYC (200 mg/kg) administered over 4 days, 7 of 12 patients were readmitted to hospital with neutropenic fever 4. Of particular importance to patients of childbearing age, CYC is recognized to have gonadal toxicity with a risk of permanent infertility 13. Hemorrhagic cystitis and late bladder cancers can occur as a consequence of the excretion of the toxic metabolite, acrolein, however this risk is much reduced with periodic IV dosing 14. Perhaps most feared is the increased risk of malignancy such as leukemia, lymphoma, skin cancer, and solid malignancies 15,16. It is worth noting however, that all patients on long-term immunosuppression, including our treatment-refractory MG cohort, are likely at increased risk of malignancy independent of CYC treatment (reviewed in
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
17,18
). The risk of CYC toxicity is related to the cumulative dose, duration of therapy, and
route of delivery. In an effort to reduce the short-term treatment side effects, our protocol used lower doses of pulsed IV CYC that could be administered safely in an outpatient setting. The maximum total treatment dose of CYC in our study was 9 g. Two patients developed mild neutropenia and 1 patient additionally had mild anemia, however no patients required hematological support. Furthermore, no patient required readmission for acute treatment side effects. Overall, CYC treatment was well tolerated. Since our lower dose regimen avoided much of the acute toxicity seen with higher dose protocols, this protocol may be tolerated better in older patients or patients with significant medical comorbidities. Most importantly, the reduced intensity protocol reduced the risk of potentially serious side effects without appearing to compromise efficacy. The management of treatment-refractory MG is challenging. Many of the long-term immunosuppressant treatments tested in patients with MG have a delayed onset of therapeutic action. A study by Palace et al (1998) showed that the benefits of azathioprine typically begin after 15 months of treatment 19. A number of case reports, case series, and an open-label pilot study have described a treatment benefit of mycophenolate in MG after 6 months or more of treatment (reviewed in 20). The delayed onset of any therapeutic benefit of mycophenolate in MG is further illustrated by the negative results of 2 phase III randomized controlled trials, both of which have been criticized for their short duration (12 weeks and 36 weeks, respectively, 21,22). Furthermore, methotrexate has been suggested to be comparable to azathioprine in generalized MG after 10 months of treatment 23. Unfortunately, these long treatment latencies can result in patients remaining severely impaired from MG and at risk of a myasthenic crisis for many months or years. Some patients may not achieve disease control despite prolonged trials of these antiproliferative medications. A prompt onset, effective, safe treatment with the potential to induce long-term clinical remission remains the goal of MG therapy. We and others have shown that the clinical
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 10 of 25
Page 11 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page11
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
improvement observed following CYC administration in MG is relatively rapid 4. Of the patients who responded to CYC in our study, all showed a reduction in MGC within 3 months of treatment onset, and 2 of 6 patients had substantial clinical improvement within 1 month. The rapid therapeutic benefit of CYC is not only beneficial for patients with disabling weakness; it also allows reduction of corticosteroids, thus reducing the associated adverse effects. Furthermore, clinical improvement following CYC reduces the need for intermittent PLEX and IVIG; treatments associated with substantial cost and some risk. Rituximab is used increasingly in treatment of many autoimmune conditions, particularly those with a proposed B cell-related pathogenic mechanism. Case reports and case series have suggested that rituximab can produce rapid clinical improvement and long-term clinical remission in patients with severe, refractory MG 24-27. Diaz-Manera (2012) compared the clinical response to rituximab in MuSK and AChR antibody positive MG 25. All 6 MuSK antibody positive patients had a sustained clinical improvement following a single course of rituximab. In comparison, while 10 of 11 AChR antibody positive patients improved after rituximab, 6 patients required multiple courses of rituximab for ongoing clinical benefit. Rituximab clearly has a role in the treatment of refractory MG, however its use has a number of key limitations: (1) it remains unlicensed and unfunded for the treatment of MG and is expensive compared to CYC; (2) emerging clinical evidence suggests it may be less effective in AChR compared to MuSK antibody positive MG; and (3) there are practical difficulties using rituximab with concurrent PLEX. Randomized controlled trials comparing CYC and rituximab in the treatment of refractory MG are strongly recommended. We sought to identify biomarkers associated with clinical response to CYC within our cohort. Results from animal and human studies have shown that high dose CYC treatment reduces circulating AChR antibody levels 4 28. It has been suggested that rising AChR antibody levels following CYC treatment may be a predictor of impending relapse 4. We found that AChR antibodies were consistently below pre-treatment levels in 3 patients with a sustained clinical
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
response following CYC. In contrast, AChR antibody levels either remained elevated or increased in patients who responded partially or failed to respond to CYC. These findings suggest that a sustained reduction in AChR antibodies following CYC may predict patients who are more likely to remain in clinical remission. In addition, a lower leukocyte nadir during high-dose CYC treatment has been suggested to correlate with a more favorable clinical course 4. Our results support this hypothesis; the patients who had the highest leukocyte nadir during the treatment period had the least favorable clinical outcome. As well as being a predictor of poor response, it is possible that higher leukocyte nadirs reflect inadequate CYC dosing. It may be appropriate to titrate the CYC dose, aiming for a sub-normal, but not dangerously low, leukocyte count in an effort to maximize clinical response as has been utilized previously 12. Protocols using remission-induction CYC followed by maintenance with a less toxic immunosuppressive agent have been used successfully in other autoimmune diseases. These regimens have been shown to reduce toxicity without compromising efficacy 6,7. We show here that this approach can also effectively treat moderate or severe, refractory MG and produce sustained clinical remission in a significant proportion of patients. The capacity to induce rapid clinical improvement and long-term remission may be particularly appealing to older patients with refractory MG, where maintenance of fertility is less important and where adverse effects of corticosteroids may have greater consequences. Overall, our regimen of remission-inducing pulsed IV CYC following by maintenance oral immunosuppression provides patients with refractory MG a rapid, inexpensive, efficacious, durable, and well-tolerated treatment option. Finally, in the absence of randomized clinical trials, we advocate combining multicenter treatment and outcome data into observational longitudinal patient registries to generate robust outcome data on which to base future clinical decisions.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 12 of 25
Page 13 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page13
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Abbreviations Acetylcholine receptor, AChR; azathioprine, Aza; cyclophophosphamide, CYC; gastrointestinal tract, GIT; granulocyte colony-stimulating factor, G-CSF; hypogammaglobulinemia, hypogamm; intravenous, IV; intravenous immunoglobulin, IVIG; low density lipoprotein receptor-related protein 4, Lrp4; max, maximum; methotrexate, MTX; muscle-specific tyrosine kinase, MuSK; myasthenia gravis, MG; myasthenia gravis composite, MGC; Myasthenia Gravis Foundation of America, MGFA; mycophenolate, MMF; not applicable, n/a; osteopenia, OPE; osteoporosis, OPO; plasma exchange, PLEX; prednisone, pred; pyridostigmine, pyrid; rituximab, Ritux; thym, thymectomy; urinary tract infection, UTI; ventilator acquired pneumonia, VAP
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
References 1.
Perez MC, Buot WL, Mercado-Danguilan C, Bagabaldo ZG, Renales LD. Stable
remissions in myasthenia gravis. Neurology 1981;31(1):32-37. 2.
Gladstone DE, Brannagan TH, 3rd, Schwartzman RJ, Prestrud AA, Brodsky I. High
dose cyclophosphamide for severe refractory myasthenia gravis. J Neurol Neurosurg Psychiatry 2004;75(5):789-791. 3.
Lin PT, Martin BA, Weinacker AB, So YT. High-dose cyclophosphamide in refractory
myasthenia gravis with MuSK antibodies. Muscle Nerve 2006;33(3):433-435. 4.
Drachman DB, Adams RN, Hu R, Jones RJ, Brodsky RA. Rebooting the immune
system with high-dose cyclophosphamide for treatment of refractory myasthenia gravis. Ann NY Acad Sci 2008;1132:305-314. 5.
DeZern AE, Petri M, Drachman DB, Kerr D, Hammond ER, Kowalski J, Tsai HL,
Loeb DM, Anhalt G, Wigley F, Jones RJ, Brodsky RA. High-dose cyclophosphamide without stem cell rescue in 207 patients with aplastic anemia and other autoimmune diseases. Medicine 2011;90(2):89-98. 6.
Jayne D, Rasmussen N, Andrassy K, Bacon P, Tervaert JW, Dadoniene J, Ekstrand
A, Gaskin G, Gregorini G, de Groot K, Gross W, Hagen EC, Mirapeix E, Pettersson E, Siegert C, Sinico A, Tesar V, Westman K, Pusey C. A randomized trial of maintenance therapy for vasculitis associated with antineutrophil cytoplasmic autoantibodies. N Engl J Med 2004 2003;349(1):36-44. 7.
Contreras G, Pardo V, Leclercq B, Lenz O, Tozman E, O'Nan P, Roth D. Sequential
therapies for proliferative lupus nephritis. N Engl J Med 2004;350(10):971-980. 8.
Jaretzki A, 3rd, Barohn RJ, Ernstoff RM, Kaminski HJ, Keesey JC, Penn AS,
Sanders DB. Myasthenia gravis: recommendations for clinical research standards. Task
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 14 of 25
Page 15 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of America. Ann Thorac Surg 2000;70(1):327-334. 9.
Burns TM, Conaway M, Sanders DB. The MG Composite: A valid and reliable
outcome measure for myasthenia gravis. Neurology 2010;74(18):1434-1440. 10.
Riminton DS, Hartung HP, Reddel SW. Managing the risks of immunosuppression.
Curr Opin Neurol 2011;24(3):217-223. 11.
Riminton DS, Reddel S, Marshall R. Immunosuppression Screen homepage. 2011.
Available at http://immunosuppressionscreen.net.au/2011/Home.htm. Accessed 2014 Aug 29. 12.
De Feo LG, Schottlender J, Martelli NA, Molfino NA. Use of intravenous pulsed
cyclophosphamide in severe, generalized myasthenia gravis. Muscle Nerve 2002;26(1):3136. 13.
Wang CL, Wang F, Bosco JJ. Ovarian failure in oral cyclophosphamide treatment for
systemic lupus erythematosus. Lupus 1995;4(1):11-14. 14.
Monach PA, Arnold LM, Merkel PA. Incidence and prevention of bladder toxicity from
cyclophosphamide in the treatment of rheumatic diseases: a data-driven review. Arthritis Rheum 2010;62(1):9-21. 15.
Radis CD, Kahl LE, Baker GL, Wasko MC, Cash JM, Gallatin A, Stolzer BL, Agarwal
AK, Medsger TA, Jr., Kwoh CK. Effects of cyclophosphamide on the development of malignancy and on long-term survival of patients with rheumatoid arthritis. A 20-year followup study. Arthritis Rheum 1995;38(8):1120-1127. 16.
Bernatsky S, Clarke AE, Suissa S. Hematologic malignant neoplasms after drug
exposure in rheumatoid arthritis. Arch Intern Med 2008;168(4):378-381.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
17.
Weaver JL. Establishing the carcinogenic risk of immunomodulatory drugs. Toxicol
Pathol 2012;40(2):267-271. 18.
Grulich AE, van Leeuwen MT, Falster MO, Vajdic CM. Incidence of cancers in people
with HIV/AIDS compared with immunosuppressed transplant recipients: a meta-analysis. Lancet 2007;370(9581):59-67. 19.
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(6):1778-1783. 20.
Heatwole C, Ciafaloni E. Mycophenolate mofetil for myasthenia gravis: a clear and
present controversy. Neuropsychiatric Disease and Treatment 2008;4(6):1203-1209. 21.
Muscle Study Group. A trial of mycophenolate mofetil with prednisone as initial
immunotherapy in myasthenia gravis. Neurology 2008;71(6):394-399. 22.
Sanders DB, Hart IK, Mantegazza R, Shukla SS, Siddiqi ZA, De Baets MH, Melms A,
Nicolle MW, Solomons N, Richman DP. An international, phase III, randomized trial of mycophenolate mofetil in myasthenia gravis. Neurology 2008;71(6):400-406. 23.
Heckmann JM, Rawoot A, Bateman K, Renison R, Badri M. A single-blinded trial of
methotrexate versus azathioprine as steroid-sparing agents in generalized myasthenia gravis. BMC Neurol 2011;11:97. 24.
Blum S, Gillis D, Brown H, Boyle R, Henderson R, Heyworth-Smith D, Hogan P,
Kubler P, Lander C, Limberg N, Pillans P, Prain K, Staples C, Walsh M, McCombe P, Wong R. Use and monitoring of low dose rituximab in myasthenia gravis. J Neurol Neurosurg Psychiatry 2011;82(6):659-663. 25.
Diaz-Manera J, Martinez-Hernandez E, Querol L, Klooster R, Rojas-Garcia R,
Suarez-Calvet X, Munoz-Blanco JL, Mazia C, Straasheijm KR, Gallardo E, Juarez C,
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 16 of 25
Page 17 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page17
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Verschuuren JJ, Illa I. Long-lasting treatment effect of rituximab in MuSK myasthenia. Neurology 2012;78(3):189-193. 26.
Keung B, Robeson KR, DiCapua DB, Rosen JB, O'Connor KC, Goldstein JM, Nowak
RJ. Long-term benefit of rituximab in MuSK autoantibody myasthenia gravis patients. J Neurol Neurosurg Psychiatry 2013;84(12):1407-1409. 27.
Nowak RJ, Dicapua DB, Zebardast N, Goldstein JM. Response of patients with
refractory myasthenia gravis to rituximab: a retrospective study. Therapeutic advances in neurological disorders 2011;4(5):259-266. 28.
Pestronk A, Drachman DB, Teoh R, Adams RN. Combined short-term
immunotherapy for experimental autoimmune myasthenia gravis. Ann Neurol 1983;14(2):235-241.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page18
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Disclosures: KA Buzzard has full access to all the data in the study and takes responsibility for its accuracy. KA Buzzard has received fellowship support from pharmaceutical companies including Baxter (IVIG) and CSL biological (IVIG). NJ Meyer reports no relevant disclosures. TA Hardy reports no relevant disclosures. DS Riminton reports no relevant disclosures. SW Reddel has received travel support from CSL (IVIG) and unrestricted research support from pharmaceutical companies including Baxter (IVIG) and CSL (IVIG).
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 18 of 25
Page 19 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page19
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Authorship: KA Buzzard contributed to the design and study conceptualization and collected the data. She assisted with data interpretation and drafted the manuscript. NJ Meyer assisted with data collection. He assisted with drafting and revision of the manuscript. TA Hardy contributed to the data interpretation and assisted with drafting and revision of the manuscript. DS Riminton contributed to the data interpretation and assisted with drafting and revision of the manuscript. SW Reddel contributed to the design and study conceptualization. He assisted with data interpretation and with drafting and revision of the manuscript.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Figure 1: MGC and prednisolone dose following CYC * MGC and prednisolone dose at last follow-up were only achieved after retreatment with high dose rituximab.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 20 of 25
Page 21 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page21
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Table 1: Patient characteristics prior to CYC
Age
Patient 1
Patient 2
Patient 3
Patient 4
Patient 5
Patient 6
Patient 7
Patient 8
58/ M
65/ M
76/ M
54/ W
73/ W
29/ M
60/ M
44/ M
AChR
Sero-
AChR
AChR
AChR
MuSK
AChR
AChR
(years)/ gender
Antibody status
Duration of
negative
11
7
172
4
45
7
5
79
19
12
25
34
31
25
17
13
IVb
IIIa
IVb
IVb
V
IVb
IVb
IIIa
Previous
Pred 20
Pred 50
Pred 20
Pred 25
Pred 40
Pred 25
Pred 50
Pred 12.5
therapy
mg, PLEX,
mg, Pyr,
mg, PLEX,
mg, IVIG,
mg, IVIG,
mg, PLEX,
mg, PLEX,
mg, MMF,
(most
Pyr, Thym
IVIG
MMF, Pyr,
PLEX, Pyr
PLEX, Pyr,
Aza, IVIG,
Aza, Pyr,
PLEX, Pyr,
Aza, Thym
Ritux, Pyr
IVIG, Thym
Ritux, Aza,
MG (months)
Estimated MGC nadir pre-CYC (max 50)
MGFA nadir preCYC
recent
Aza
shown in
IVIG, Thym
italics)
Side-
OPE, liver
OPO,
OPE, deep
OPO,
OPE,
toxicity
impaired
vein
pulmonary
obesity,
obesity,
from
glucose
thrombosis
embolus,
sepsis,
Dressler’s
previous
tolerance
sepsis, GIT
aseptic
syndrome
upset,
meningitis
effects
treatment
OPO, rash
hypogamm.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
OPE
OPE,
Muscle & Nerve Cyclophosphamide in refractory MG, page22
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Max, maximum; OPO, osteoporosis; OPE, osteopenia; Pred, prednisolone; PLEX, plasma exchange; Pyr, pyridostigmine; Thym, thymectomy; IVIG, intravenous immunoglobulin; MMF, mycophenolate mofetil; Aza, azathioprine; Ritux, rituximab; GIT, gastrointestinal; hypogamm; hypogammablobulinemia
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 22 of 25
Page 23 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Table 2: Patient response to CYC
Time to
Patient 1
Patient 2
Patient 3
Patient 4
Patient 5
Patient 6
Patient 7
Patient 8
2
2
2
1
3
n/a
1
n/a
0
0
2
0
0
3 Ϯ (17)
3
5
38
49
58
29
15
19
34
8
>38*
>49
11
>29
>15
n/a
>34
n/a
MMF
MMF
Pred 12.5
Aza
Pred 2.5
Pred 12.5
Pred 12.5
Pred 12.5
mg, MTX
mg, Aza,
mg, MMF,
mg, PLEX,
Ritux
Pyr
MMF, Pyr
Mild
Mild
Mild
Nil
neutro-
nausea
neutro-
improvement (months)
Best MGC post-CYC (max 50)
Duration of followup postCYC (months)
Duration of benefit (months)
Treatment at last
mg, PLEX,
follow-up
MMF, Pyr
Side-
Mild
effects of
nausea
CYC
Nil
Nil
UTI
penia,
penia
anemia, VAP
Max, maximum; Pred, prednisolone; PLEX, plasma exchange; MMF, mycophenolate mofetil; Pyr, pyridostigmine; Aza, azathioprine; MTX, methotrexate; Ritux, rituximab; UTI, urinary tract infection; VAP, ventilator acquired pneumonia; n/a, not applicable
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page24
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
*Mild weakness at month-17 requiring re-initiation of prednisolone 5 mg, successfully tapered over 12 months. Ϯ MGC=3 achieved only after further rituximab treatment post-CYC. Prior to rituximab, best MGC=17
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 24 of 25
Page 25 of 25
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Muscle & Nerve
152x191mm (300 x 300 DPI)
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Supplementary Figure S1: AChR antibody levels in seropositive patients following CYC Clinical remission, CR; partial responder, PR; non-responder, NR
This article is protected by copyright. All rights reserved.
Supplementary Figure S2: Leukocyte nadir during CYC treatment Clinical remission, CR; partial responder, PR; non-responder, NR
This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Induction IV cyclophosphamide followed by maintenance oral immunosuppression in refractory myasthenia gravis Katherine A. Buzzard1, MBBS PhD, Nicholas J. Meyer2, BSc, Todd A. Hardy1, MBBS PhD, D. Sean Riminton2, MBBS PhD, Stephen W. Reddel1, MBBS PhD. 1
Department of Neurology, Concord Repatriation General Hospital, Concord West, New
South Wales, Australia 2
Department of Immunology, Concord Repatriation General Hospital, Concord West, New
South Wales, Australia
Corresponding Author: Stephen W. Reddel, Department of Neurology, Concord Repatriation General Hospital, 2139, New South Wales, Australia; Ph: +61297676129, Fax: +61292100533, email: [email protected]
Running Title: Cyclophosphamide in refractory MG
th
This paper was presented at the 4 International Conference, Advances in Clinical Neuroimmunology, Krakow, Poland, 27-28 June 2014.
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as an ‘Accepted Article’, doi: 10.1002/mus.24536 This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Induction IV cyclophosphamide followed by maintenance oral immunosuppression in refractory myasthenia gravis Introduction: Myasthenia gravis (MG) can be refractory to conventional immunotherapy. We report on the efficacy and durability of intravenous remission-induction cyclophosphamide (CYC) followed by oral immunosuppression in refractory MG. Methods: We identified 8 patients from our medical records with moderate or severe refractory MG who were treated with 6 cycles of 4-weekly IV-CYC (0.75 g/m2) followed by oral immunosuppression. Results: Six patients improved within 3 months of treatment. Four patients remained in clinical remission (mean follow-up 31 months). Two patients responded partially, and 1 patient relapsed after 11 months. Two patients were non-responders. CYC was well tolerated. Acetylcholine receptor antibody levels remained below pre-treatment levels in patients in clinical remission. The leukocyte nadir was lower in CYC responders. Conclusions: Remission-induction IV-CYC followed by oral immunosuppression is a rapid, effective, and durable treatment for refractory MG. Adding a post-CYC immunosuppressant may account for low relapse rates compared to other published series.
Keywords Myasthenia gravis, refractory, cyclophosphamide, immunosuppression, treatment
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 2 of 25
Page 3 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Introduction Myasthenia gravis (MG) is a chronic autoimmune disease of the neuromuscular junction characterized by fluctuating weakness. In most cases, MG can be treated effectively with symptomatic and immunomodulatory treatments such as pyridostigmine, corticosteroids, azathioprine, mycophenolate, cyclosporine, and methotrexate. A subset of MG patients however, experience progressive, relapsing, and disabling disease despite conventional immune therapies. The disease course in these treatment-refractory patients is often characterized by frequent hospitalization due to severe respiratory or bulbar symptoms requiring “rescue” therapy with plasma exchange (PLEX) and intravenous (IV) immunoglobulin (IVIG). These patients frequently bear the consequences of long-term highdose corticosteroid therapy, including osteoporosis, obesity, and diabetes mellitus, among others. Cyclophosphamide (CYC) has generated interest as an effective second-line agent for treatment of refractory MG. Several groups have shown that high-dose CYC can induce at least short-term disease remission in patients with severe, refractory MG1-5. A limitation of CYC treatment appears to be the duration of benefit; most studies have reported that patients relapse and require further escalation of immunomodulatory therapy. An additional concern is the potential for short- and long-term toxicity with high-dose CYC regimens. The cumulative dose of CYC can be reduced by using protocols based on induction CYC followed by maintenance with a less toxic immunosuppressive agent. These protocols have been used successfully in clinical trials of patients with lupus nephritis, granulomatosis with polyangiitis, and microscopic polyangiitis and have been shown to result in reduced toxicity without compromising efficacy 6,7. We report on the efficacy, durability, and safety of remission-induction pulsed IV CYC followed by maintenance oral immunosuppression in 8 patients with moderate or severe, refractory myasthenia gravis followed for 8-58 months. We demonstrate that this reduced
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
intensity regimen shows efficacy in inducing disease remission and avoids the complication of severe cytopenias. We also suggest that routine administration of maintenance oral immunosuppression may reduce the risk of subsequent relapse. Methods: Eighty-two patients with a diagnosis of MG were identified from a database of patients followed in the Neuroimmunology clinic at Concord Hospital. This clinic focuses on the treatment of patients with moderate to severe neuroimmunological disorders requiring complex therapy. Treatment-refractory MG patients were identified based on resistance, toxicities, or contraindications to conventional immunosuppressive treatments, and/or dependence on PLEX or IVIG according to previous studies 4. Eight patients with treatmentrefractory MG were treated with CYC during the course of their disease. Clinical and demographic data were extracted from the medical records of each patient. Each patient’s worst disease status was rated according to the Myasthenia Gravis Foundation of America (MGFA) classification (Grade I=ocular disease only, Grade II= mild weakness, Grade III=moderate weakness, Grade IV=severe weakness, Grade V = assisted ventilation; the “a” subtype denotes predominantly limb/axial muscles, and the “b” subtype denotes predominantly bulbar/respiratory muscles) 8. Clinical disease severity was also calculated according to the Myasthenia Gravis Composite (MGC) scale, which uses data routinely collected at consultation 9. When the MGC was derived retrospectively from clinical symptoms and examination findings documented in the medical record, the term “estimated MGC” is used to reflect the minimum calculated MGC. Patients gave informed consent for CYC after discussion of the risks and benefits of treatment. Patients underwent an immunosuppression risk management assessment prior to starting treatment (www.immunosuppressionscreen.net, accession date 18th July 2014)10,11. Infusions were given in the outpatient setting unless the MG severity required hospital admission. Each infusion was subject to a satisfactory neutrophil count (>1.5 x109/L) in the 2
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 4 of 25
Page 5 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
weeks prior to each cycle. CYC (0.75 g/m2) was infused via peripheral IV access every 4 weeks for 6 cycles. The maximum dose of CYC was set at 1500 mg per cycle. The dose was reduced to 0.5 g/m2 if the glomerular filtration rate was less than 30% of normal. Smaller individual dose reductions were made if the neutrophil count fell below 1.5 x109/L at the 1014 day nadir. Patients received prophylactic anti-emetics concurrently with granisetron and dexamethasone with each cycle of CYC. Pneumocystis jiroveci pneumonia prophylaxis with Cotrimoxazole was given to all patients during the treatment period and for 1 month after the last course of CYC. One month after completing the 6th cycle of CYC, patients were started on maintenance immunotherapy with mycophenolate, azathioprine, or methotrexate. Acetylcholine receptor (AChR) and muscle-specific tyrosine kinase (MuSK) antibodies were measured by radioimmunoassays following the manufacturer’s instructions (RSR, UK). This study was conducted in accordance with the Declaration of Helsinki with approval by the human research ethics committee of Concord Hospital. Results: Patient characteristics Eight patients received treatment with 6 cycles of 4-weekly IV pulsed CYC (0.75 g/m2) between October 2008 and October 2013 (Table 1). Each patient had a definite diagnosis of MG based on typical clinical symptoms and examination findings, together with confirmatory electrophysiological studies and/or antibodies to AChR (n=6) or MuSK (n=1). One patient was seronegative for AChR, MuSK, and low-density lipoprotein receptor-related protein 4 (Lrp4) antibodies. There were 6 male and 2 women with a mean age of 57 years (range 2976 years). Disease duration at the time of CYC treatment ranged from 4-172 months (median 63 months). Six patients (patients 1, 3, 4, 6, 7, and 8) received CYC in the context of moderate or severe MG (MGFA grade III-IV) despite PLEX and moderate to high-dose prednisone (equivalent to 12.5-50 mg daily) in conjunction with other immunomodulatory therapy (Table 1). Treatment with CYC was initiated during a respiratory crisis in 1 patient
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
(patient 5) who had only a limited response to frequent PLEX and IVIG. The decision to treat one patient (patient 2) with CYC was made based on moderate MG symptoms (MGFA grade IIIb) requiring high dose prednisone, together with extensive medical co-morbidities limiting the use of alternative immunomodulatory therapy. Each patient had experienced MG treatment side effects prior to the initiation of CYC (Table 1). All patients had documented osteopenia or osteoporosis as a likely consequence of prolonged corticosteroid therapy. Clinical response Six patients had dramatic improvement in clinical symptoms and estimated MGC during the 6-month treatment period (Figure 1). The mean time to onset of clinical improvement was 2 months (range 1-3 months) (Table 2). Clinical improvement allowed reduction in prednisone dose during the treatment period in all 6 patients. At last follow-up, 4 patients remained in clinical remission (MGC 0) on maintenance therapy. Three of these patients (patients 1, 2, and 4) were stable on either azathioprine or mycophenolate, having ceased prednisone at month 15, 22, and 9, respectively (Table 2). Patient 1 was temporarily restarted on low dose prednisone (5 mg daily) at 17 months after developing mild proximal weakness, however this was subsequently weaned over 12 months. The fourth patient in clinical remission (patient 5) remains on low dose prednisone (equivalent to 2.5 mg daily) and methotrexate at last followup (15 months). Two patients responded partially to CYC. Patient 3 improved clinically during the treatment period and was able to halve his prednisone dose and cease PLEX. However, he relapsed 11 months after starting CYC, requiring re-escalation of prednisone and short-term PLEX. Patient 7 improved dramatically following CYC treatment, which allowed his prednisone dose to be weaned substantially and PLEX to be withdrawn. He continues to have mild bulbar symptoms and remains on a moderate dose of prednisone, regular pyridostigmine, and mycophenolate. Two patients were considered non-responders to CYC. Prior to CYC, patient 6 (MuSK antibody positive) was PLEX-dependent despite prednisone, azathioprine, and rituximab
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 6 of 25
Page 7 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page7
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
treatment (2x 500 mg given 4 weeks apart) completed 5 months prior to CYC and resulting in transient B-cell depletion (lasting less than 5 months). He deteriorated during the CYC treatment (Figure 1). Later treatment with high dose rituximab (1000mg weekly for 4 weeks) resulted in marked clinical improvement and prolonged peripheral blood B-cell depletion. Patient 8 had transient reduction in his MGC at 3 months, however his symptoms worsened toward the end of the CYC treatment period (Figure 1). He continued to require intensive immunomodulatory therapy with weekly PLEX, moderate doses of prednisone, and regular pyridostigmine and was considered to be a CYC non-responder. Treatment tolerability Treatment with CYC was tolerated well in all patients. Mild subclinical neutropenia was observed in 2 patients prompting a slight dose reduction at the subsequent treatment cycle. Any cytopenias were mild, and no patients required support with blood products or granulocyte colony-stimulating factor (G-CSF). Patient 7 underwent an emergency laparotomy for a bowel perforation secondary to pneumatosis coli after CYC cycle 2. This was felt to be related to high-dose IV methylprednisolone administered shortly beforehand, rather than a complication of CYC. Two patients (patients 5 and 4) were diagnosed with infections during the CYC treatment period; patient 5 was treated for ventilator-acquired pneumonia during the acute myasthenia crisis, while patient 4 developed a minor urinary tract infection. Both patients made a full recovery with no long-term sequelae. There have been no reports of malignancies in the follow-up period to date. Laboratory investigations AChR antibody levels pre- and post-CYC for the 6 seropositive patients showed partial concordance with clinical outcome (supplementary Figure S1, available online). Antibody levels fell initially in 4 patients. At last follow-up, AChR antibody levels remained below pretreatment levels in 3 patients with sustained clinical remission, whereas the antibody level had returned to pre-treatment level within 12 months of CYC in a partial responder. AChR
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
antibody levels remained unchanged or increased in 2 patients; 1 patient was a clinical nonresponder to CYC and the other had initial improvement following CYC but subsequently relapsed. All patients underwent frequent full blood examination to monitor for cytopenias during their CYC treatment period. Four patients developed a peripheral blood leukocyte count nadir below the normal range (supplementary Figure S2, available online). These patients all had at least a partial response to CYC. The 2 patients who were clinical non-responders had the highest leukocyte count nadir, remaining well within the normal range (5.5 x109/L and 6.1 x109/L, normal 4.0-10.0 x109/L). Discussion In this retrospective case series of highly selected patients with moderate or severe refractory MG, we have shown that pulsed IV CYC administered every 4 weeks for 6 cycles followed by conventional oral immunotherapy was associated with marked clinical improvement in 6 of 8 patients (75%). Improvement allowed oral corticosteroids to be tapered during the treatment period in all 6 patients. Corticosteroid reduction was of particular relevance in this patient cohort, since all 8 patients had experienced complications from long-term steroid therapy. Four patients (50%) achieved clinical remission while on maintenance therapy, 3 of whom were also able to completely withdraw prednisone. Our results support the findings of other published studies that have shown the efficacy of CYC in patients with severe, refractory MG 1,2,3,4,5,12. Disappointingly, many of these studies have shown that the benefits of CYC are often short-lived, and the majority of patients have relapsed. One of the largest published series by Drachman et al (2008) reported 11 of 12 patients with severe, refractory MG improved after high-dose CYC, however only 2 patients had a durable response without the need for subsequent treatment escalation 4.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 8 of 25
Page 9 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page9
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The precise mechanism of action of CYC in the treatment of MG remains unclear. At least some of its therapeutic action may relate to the capacity of CYC to induce lymphocyte apoptosis, resulting in a quantitative reduction in the activated lymphocyte populations that are responsible for driving new plasmablast and plasma cell formation. In turn, this would reduce the production of pathogenic autoantibodies. We hypothesized that introducing a maintenance anti-proliferative immunosuppressant following remission-induction CYC could prevent re-emergence of the pathogenic activated lymphocytes, thereby prolonging clinical remission. We routinely treated patients with a conventional oral immunosuppressant after completion of 6 cycles of CYC. Of the 6 patients who responded clinically to CYC, only 1 had subsequently relapsed at last follow-up. Although the patient numbers are small, the low relapse rate to date supports the hypothesis that routine addition of maintenance oral immunosuppression may prolong the clinical response to CYC. Many of the published studies showing the benefit of CYC in the treatment of severe, refractory MG have employed high dose regimens or prolonged treatment courses, resulting in higher cumulative doses of CYC 1,4,5. CYC carries a risk of serious adverse effects. In the short-term, bone marrow suppression and severe leukopenia put patients at risk of septicemia and life-threatening infections. High-dose regimens typically result in severe cytopenias requiring blood products and G-CSF. In the study by Drachman et al (2008) which utilized high-dose CYC (200 mg/kg) administered over 4 days, 7 of 12 patients were readmitted to hospital with neutropenic fever 4. Of particular importance to patients of childbearing age, CYC is recognized to have gonadal toxicity with a risk of permanent infertility 13. Hemorrhagic cystitis and late bladder cancers can occur as a consequence of the excretion of the toxic metabolite, acrolein, however this risk is much reduced with periodic IV dosing 14. Perhaps most feared is the increased risk of malignancy such as leukemia, lymphoma, skin cancer, and solid malignancies 15,16. It is worth noting however, that all patients on long-term immunosuppression, including our treatment-refractory MG cohort, are likely at increased risk of malignancy independent of CYC treatment (reviewed in
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
17,18
). The risk of CYC toxicity is related to the cumulative dose, duration of therapy, and
route of delivery. In an effort to reduce the short-term treatment side effects, our protocol used lower doses of pulsed IV CYC that could be administered safely in an outpatient setting. The maximum total treatment dose of CYC in our study was 9 g. Two patients developed mild neutropenia and 1 patient additionally had mild anemia, however no patients required hematological support. Furthermore, no patient required readmission for acute treatment side effects. Overall, CYC treatment was well tolerated. Since our lower dose regimen avoided much of the acute toxicity seen with higher dose protocols, this protocol may be tolerated better in older patients or patients with significant medical comorbidities. Most importantly, the reduced intensity protocol reduced the risk of potentially serious side effects without appearing to compromise efficacy. The management of treatment-refractory MG is challenging. Many of the long-term immunosuppressant treatments tested in patients with MG have a delayed onset of therapeutic action. A study by Palace et al (1998) showed that the benefits of azathioprine typically begin after 15 months of treatment 19. A number of case reports, case series, and an open-label pilot study have described a treatment benefit of mycophenolate in MG after 6 months or more of treatment (reviewed in 20). The delayed onset of any therapeutic benefit of mycophenolate in MG is further illustrated by the negative results of 2 phase III randomized controlled trials, both of which have been criticized for their short duration (12 weeks and 36 weeks, respectively, 21,22). Furthermore, methotrexate has been suggested to be comparable to azathioprine in generalized MG after 10 months of treatment 23. Unfortunately, these long treatment latencies can result in patients remaining severely impaired from MG and at risk of a myasthenic crisis for many months or years. Some patients may not achieve disease control despite prolonged trials of these antiproliferative medications. A prompt onset, effective, safe treatment with the potential to induce long-term clinical remission remains the goal of MG therapy. We and others have shown that the clinical
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 10 of 25
Page 11 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page11
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
improvement observed following CYC administration in MG is relatively rapid 4. Of the patients who responded to CYC in our study, all showed a reduction in MGC within 3 months of treatment onset, and 2 of 6 patients had substantial clinical improvement within 1 month. The rapid therapeutic benefit of CYC is not only beneficial for patients with disabling weakness; it also allows reduction of corticosteroids, thus reducing the associated adverse effects. Furthermore, clinical improvement following CYC reduces the need for intermittent PLEX and IVIG; treatments associated with substantial cost and some risk. Rituximab is used increasingly in treatment of many autoimmune conditions, particularly those with a proposed B cell-related pathogenic mechanism. Case reports and case series have suggested that rituximab can produce rapid clinical improvement and long-term clinical remission in patients with severe, refractory MG 24-27. Diaz-Manera (2012) compared the clinical response to rituximab in MuSK and AChR antibody positive MG 25. All 6 MuSK antibody positive patients had a sustained clinical improvement following a single course of rituximab. In comparison, while 10 of 11 AChR antibody positive patients improved after rituximab, 6 patients required multiple courses of rituximab for ongoing clinical benefit. Rituximab clearly has a role in the treatment of refractory MG, however its use has a number of key limitations: (1) it remains unlicensed and unfunded for the treatment of MG and is expensive compared to CYC; (2) emerging clinical evidence suggests it may be less effective in AChR compared to MuSK antibody positive MG; and (3) there are practical difficulties using rituximab with concurrent PLEX. Randomized controlled trials comparing CYC and rituximab in the treatment of refractory MG are strongly recommended. We sought to identify biomarkers associated with clinical response to CYC within our cohort. Results from animal and human studies have shown that high dose CYC treatment reduces circulating AChR antibody levels 4 28. It has been suggested that rising AChR antibody levels following CYC treatment may be a predictor of impending relapse 4. We found that AChR antibodies were consistently below pre-treatment levels in 3 patients with a sustained clinical
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
response following CYC. In contrast, AChR antibody levels either remained elevated or increased in patients who responded partially or failed to respond to CYC. These findings suggest that a sustained reduction in AChR antibodies following CYC may predict patients who are more likely to remain in clinical remission. In addition, a lower leukocyte nadir during high-dose CYC treatment has been suggested to correlate with a more favorable clinical course 4. Our results support this hypothesis; the patients who had the highest leukocyte nadir during the treatment period had the least favorable clinical outcome. As well as being a predictor of poor response, it is possible that higher leukocyte nadirs reflect inadequate CYC dosing. It may be appropriate to titrate the CYC dose, aiming for a sub-normal, but not dangerously low, leukocyte count in an effort to maximize clinical response as has been utilized previously 12. Protocols using remission-induction CYC followed by maintenance with a less toxic immunosuppressive agent have been used successfully in other autoimmune diseases. These regimens have been shown to reduce toxicity without compromising efficacy 6,7. We show here that this approach can also effectively treat moderate or severe, refractory MG and produce sustained clinical remission in a significant proportion of patients. The capacity to induce rapid clinical improvement and long-term remission may be particularly appealing to older patients with refractory MG, where maintenance of fertility is less important and where adverse effects of corticosteroids may have greater consequences. Overall, our regimen of remission-inducing pulsed IV CYC following by maintenance oral immunosuppression provides patients with refractory MG a rapid, inexpensive, efficacious, durable, and well-tolerated treatment option. Finally, in the absence of randomized clinical trials, we advocate combining multicenter treatment and outcome data into observational longitudinal patient registries to generate robust outcome data on which to base future clinical decisions.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 12 of 25
Page 13 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page13
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Abbreviations Acetylcholine receptor, AChR; azathioprine, Aza; cyclophophosphamide, CYC; gastrointestinal tract, GIT; granulocyte colony-stimulating factor, G-CSF; hypogammaglobulinemia, hypogamm; intravenous, IV; intravenous immunoglobulin, IVIG; low density lipoprotein receptor-related protein 4, Lrp4; max, maximum; methotrexate, MTX; muscle-specific tyrosine kinase, MuSK; myasthenia gravis, MG; myasthenia gravis composite, MGC; Myasthenia Gravis Foundation of America, MGFA; mycophenolate, MMF; not applicable, n/a; osteopenia, OPE; osteoporosis, OPO; plasma exchange, PLEX; prednisone, pred; pyridostigmine, pyrid; rituximab, Ritux; thym, thymectomy; urinary tract infection, UTI; ventilator acquired pneumonia, VAP
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
References 1.
Perez MC, Buot WL, Mercado-Danguilan C, Bagabaldo ZG, Renales LD. Stable
remissions in myasthenia gravis. Neurology 1981;31(1):32-37. 2.
Gladstone DE, Brannagan TH, 3rd, Schwartzman RJ, Prestrud AA, Brodsky I. High
dose cyclophosphamide for severe refractory myasthenia gravis. J Neurol Neurosurg Psychiatry 2004;75(5):789-791. 3.
Lin PT, Martin BA, Weinacker AB, So YT. High-dose cyclophosphamide in refractory
myasthenia gravis with MuSK antibodies. Muscle Nerve 2006;33(3):433-435. 4.
Drachman DB, Adams RN, Hu R, Jones RJ, Brodsky RA. Rebooting the immune
system with high-dose cyclophosphamide for treatment of refractory myasthenia gravis. Ann NY Acad Sci 2008;1132:305-314. 5.
DeZern AE, Petri M, Drachman DB, Kerr D, Hammond ER, Kowalski J, Tsai HL,
Loeb DM, Anhalt G, Wigley F, Jones RJ, Brodsky RA. High-dose cyclophosphamide without stem cell rescue in 207 patients with aplastic anemia and other autoimmune diseases. Medicine 2011;90(2):89-98. 6.
Jayne D, Rasmussen N, Andrassy K, Bacon P, Tervaert JW, Dadoniene J, Ekstrand
A, Gaskin G, Gregorini G, de Groot K, Gross W, Hagen EC, Mirapeix E, Pettersson E, Siegert C, Sinico A, Tesar V, Westman K, Pusey C. A randomized trial of maintenance therapy for vasculitis associated with antineutrophil cytoplasmic autoantibodies. N Engl J Med 2004 2003;349(1):36-44. 7.
Contreras G, Pardo V, Leclercq B, Lenz O, Tozman E, O'Nan P, Roth D. Sequential
therapies for proliferative lupus nephritis. N Engl J Med 2004;350(10):971-980. 8.
Jaretzki A, 3rd, Barohn RJ, Ernstoff RM, Kaminski HJ, Keesey JC, Penn AS,
Sanders DB. Myasthenia gravis: recommendations for clinical research standards. Task
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 14 of 25
Page 15 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of America. Ann Thorac Surg 2000;70(1):327-334. 9.
Burns TM, Conaway M, Sanders DB. The MG Composite: A valid and reliable
outcome measure for myasthenia gravis. Neurology 2010;74(18):1434-1440. 10.
Riminton DS, Hartung HP, Reddel SW. Managing the risks of immunosuppression.
Curr Opin Neurol 2011;24(3):217-223. 11.
Riminton DS, Reddel S, Marshall R. Immunosuppression Screen homepage. 2011.
Available at http://immunosuppressionscreen.net.au/2011/Home.htm. Accessed 2014 Aug 29. 12.
De Feo LG, Schottlender J, Martelli NA, Molfino NA. Use of intravenous pulsed
cyclophosphamide in severe, generalized myasthenia gravis. Muscle Nerve 2002;26(1):3136. 13.
Wang CL, Wang F, Bosco JJ. Ovarian failure in oral cyclophosphamide treatment for
systemic lupus erythematosus. Lupus 1995;4(1):11-14. 14.
Monach PA, Arnold LM, Merkel PA. Incidence and prevention of bladder toxicity from
cyclophosphamide in the treatment of rheumatic diseases: a data-driven review. Arthritis Rheum 2010;62(1):9-21. 15.
Radis CD, Kahl LE, Baker GL, Wasko MC, Cash JM, Gallatin A, Stolzer BL, Agarwal
AK, Medsger TA, Jr., Kwoh CK. Effects of cyclophosphamide on the development of malignancy and on long-term survival of patients with rheumatoid arthritis. A 20-year followup study. Arthritis Rheum 1995;38(8):1120-1127. 16.
Bernatsky S, Clarke AE, Suissa S. Hematologic malignant neoplasms after drug
exposure in rheumatoid arthritis. Arch Intern Med 2008;168(4):378-381.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
17.
Weaver JL. Establishing the carcinogenic risk of immunomodulatory drugs. Toxicol
Pathol 2012;40(2):267-271. 18.
Grulich AE, van Leeuwen MT, Falster MO, Vajdic CM. Incidence of cancers in people
with HIV/AIDS compared with immunosuppressed transplant recipients: a meta-analysis. Lancet 2007;370(9581):59-67. 19.
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(6):1778-1783. 20.
Heatwole C, Ciafaloni E. Mycophenolate mofetil for myasthenia gravis: a clear and
present controversy. Neuropsychiatric Disease and Treatment 2008;4(6):1203-1209. 21.
Muscle Study Group. A trial of mycophenolate mofetil with prednisone as initial
immunotherapy in myasthenia gravis. Neurology 2008;71(6):394-399. 22.
Sanders DB, Hart IK, Mantegazza R, Shukla SS, Siddiqi ZA, De Baets MH, Melms A,
Nicolle MW, Solomons N, Richman DP. An international, phase III, randomized trial of mycophenolate mofetil in myasthenia gravis. Neurology 2008;71(6):400-406. 23.
Heckmann JM, Rawoot A, Bateman K, Renison R, Badri M. A single-blinded trial of
methotrexate versus azathioprine as steroid-sparing agents in generalized myasthenia gravis. BMC Neurol 2011;11:97. 24.
Blum S, Gillis D, Brown H, Boyle R, Henderson R, Heyworth-Smith D, Hogan P,
Kubler P, Lander C, Limberg N, Pillans P, Prain K, Staples C, Walsh M, McCombe P, Wong R. Use and monitoring of low dose rituximab in myasthenia gravis. J Neurol Neurosurg Psychiatry 2011;82(6):659-663. 25.
Diaz-Manera J, Martinez-Hernandez E, Querol L, Klooster R, Rojas-Garcia R,
Suarez-Calvet X, Munoz-Blanco JL, Mazia C, Straasheijm KR, Gallardo E, Juarez C,
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 16 of 25
Page 17 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page17
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Verschuuren JJ, Illa I. Long-lasting treatment effect of rituximab in MuSK myasthenia. Neurology 2012;78(3):189-193. 26.
Keung B, Robeson KR, DiCapua DB, Rosen JB, O'Connor KC, Goldstein JM, Nowak
RJ. Long-term benefit of rituximab in MuSK autoantibody myasthenia gravis patients. J Neurol Neurosurg Psychiatry 2013;84(12):1407-1409. 27.
Nowak RJ, Dicapua DB, Zebardast N, Goldstein JM. Response of patients with
refractory myasthenia gravis to rituximab: a retrospective study. Therapeutic advances in neurological disorders 2011;4(5):259-266. 28.
Pestronk A, Drachman DB, Teoh R, Adams RN. Combined short-term
immunotherapy for experimental autoimmune myasthenia gravis. Ann Neurol 1983;14(2):235-241.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page18
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Disclosures: KA Buzzard has full access to all the data in the study and takes responsibility for its accuracy. KA Buzzard has received fellowship support from pharmaceutical companies including Baxter (IVIG) and CSL biological (IVIG). NJ Meyer reports no relevant disclosures. TA Hardy reports no relevant disclosures. DS Riminton reports no relevant disclosures. SW Reddel has received travel support from CSL (IVIG) and unrestricted research support from pharmaceutical companies including Baxter (IVIG) and CSL (IVIG).
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 18 of 25
Page 19 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page19
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Authorship: KA Buzzard contributed to the design and study conceptualization and collected the data. She assisted with data interpretation and drafted the manuscript. NJ Meyer assisted with data collection. He assisted with drafting and revision of the manuscript. TA Hardy contributed to the data interpretation and assisted with drafting and revision of the manuscript. DS Riminton contributed to the data interpretation and assisted with drafting and revision of the manuscript. SW Reddel contributed to the design and study conceptualization. He assisted with data interpretation and with drafting and revision of the manuscript.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Figure 1: MGC and prednisolone dose following CYC * MGC and prednisolone dose at last follow-up were only achieved after retreatment with high dose rituximab.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 20 of 25
Page 21 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page21
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Table 1: Patient characteristics prior to CYC
Age
Patient 1
Patient 2
Patient 3
Patient 4
Patient 5
Patient 6
Patient 7
Patient 8
58/ M
65/ M
76/ M
54/ W
73/ W
29/ M
60/ M
44/ M
AChR
Sero-
AChR
AChR
AChR
MuSK
AChR
AChR
(years)/ gender
Antibody status
Duration of
negative
11
7
172
4
45
7
5
79
19
12
25
34
31
25
17
13
IVb
IIIa
IVb
IVb
V
IVb
IVb
IIIa
Previous
Pred 20
Pred 50
Pred 20
Pred 25
Pred 40
Pred 25
Pred 50
Pred 12.5
therapy
mg, PLEX,
mg, Pyr,
mg, PLEX,
mg, IVIG,
mg, IVIG,
mg, PLEX,
mg, PLEX,
mg, MMF,
(most
Pyr, Thym
IVIG
MMF, Pyr,
PLEX, Pyr
PLEX, Pyr,
Aza, IVIG,
Aza, Pyr,
PLEX, Pyr,
Aza, Thym
Ritux, Pyr
IVIG, Thym
Ritux, Aza,
MG (months)
Estimated MGC nadir pre-CYC (max 50)
MGFA nadir preCYC
recent
Aza
shown in
IVIG, Thym
italics)
Side-
OPE, liver
OPO,
OPE, deep
OPO,
OPE,
toxicity
impaired
vein
pulmonary
obesity,
obesity,
from
glucose
thrombosis
embolus,
sepsis,
Dressler’s
previous
tolerance
sepsis, GIT
aseptic
syndrome
upset,
meningitis
effects
treatment
OPO, rash
hypogamm.
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
OPE
OPE,
Muscle & Nerve Cyclophosphamide in refractory MG, page22
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Max, maximum; OPO, osteoporosis; OPE, osteopenia; Pred, prednisolone; PLEX, plasma exchange; Pyr, pyridostigmine; Thym, thymectomy; IVIG, intravenous immunoglobulin; MMF, mycophenolate mofetil; Aza, azathioprine; Ritux, rituximab; GIT, gastrointestinal; hypogamm; hypogammablobulinemia
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 22 of 25
Page 23 of 25
Muscle & Nerve Cyclophosphamide in refractory MG, page23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Table 2: Patient response to CYC
Time to
Patient 1
Patient 2
Patient 3
Patient 4
Patient 5
Patient 6
Patient 7
Patient 8
2
2
2
1
3
n/a
1
n/a
0
0
2
0
0
3 Ϯ (17)
3
5
38
49
58
29
15
19
34
8
>38*
>49
11
>29
>15
n/a
>34
n/a
MMF
MMF
Pred 12.5
Aza
Pred 2.5
Pred 12.5
Pred 12.5
Pred 12.5
mg, MTX
mg, Aza,
mg, MMF,
mg, PLEX,
Ritux
Pyr
MMF, Pyr
Mild
Mild
Mild
Nil
neutro-
nausea
neutro-
improvement (months)
Best MGC post-CYC (max 50)
Duration of followup postCYC (months)
Duration of benefit (months)
Treatment at last
mg, PLEX,
follow-up
MMF, Pyr
Side-
Mild
effects of
nausea
CYC
Nil
Nil
UTI
penia,
penia
anemia, VAP
Max, maximum; Pred, prednisolone; PLEX, plasma exchange; MMF, mycophenolate mofetil; Pyr, pyridostigmine; Aza, azathioprine; MTX, methotrexate; Ritux, rituximab; UTI, urinary tract infection; VAP, ventilator acquired pneumonia; n/a, not applicable
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Muscle & Nerve Cyclophosphamide in refractory MG, page24
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
*Mild weakness at month-17 requiring re-initiation of prednisolone 5 mg, successfully tapered over 12 months. Ϯ MGC=3 achieved only after further rituximab treatment post-CYC. Prior to rituximab, best MGC=17
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Page 24 of 25
Page 25 of 25
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Muscle & Nerve
152x191mm (300 x 300 DPI)
John Wiley & Sons, Inc. This article is protected by copyright. All rights reserved.
Supplementary Figure S1: AChR antibody levels in seropositive patients following CYC Clinical remission, CR; partial responder, PR; non-responder, NR
This article is protected by copyright. All rights reserved.
Supplementary Figure S2: Leukocyte nadir during CYC treatment Clinical remission, CR; partial responder, PR; non-responder, NR
This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
