Intravenous immunoglobulin monotherapy in long-term treatment of myasthenia gravis

Real-world utilization patterns of intravenous immunoglobulin in adults with generalized myasthenia gravis in the United States

OBJECTIVE

To evaluate real-world utilization patterns of intravenous immunoglobulin (IVIg) among patients with generalized myasthenia gravis (gMG) over 3 years post-IVIg initiation.

METHODS

Patients with gMG who initiated IVIg treatment were identified from a United States claims database (Symphony Health's Integrated Dataverse [IDV]®, January 1, 2014 - December 31, 2019). The frequency of subsequent IVIg treatment and associated cost during the year post-IVIg initiation were analyzed. Usage patterns of IVIg and concomitant gMG treatments during the year preceding and 3 years post-IVIg initiation were compared.

RESULTS

Among 1225 patients with gMG who initiated IVIg treatment, 706 patients (57.6%) received 1 to 5 IVIg treatment courses (intermittent IVIg users), and 519 patients (42.4%) received ≥6 IVIg treatment courses (chronic IVIg users) within the subsequent year. Mean annual medical cost per patient was nearly 2.5-fold higher for chronic vs. intermittent IVIg users ($161,478 vs. $64,888, p < 0.001). The proportion of patients using corticosteroids and nonsteroidal immunosuppressive treatments (NSISTs) was not reduced over the 3-year follow-up period following IVIg initiation, even for patients who continued annual chronic IVIg for 3 consecutive years post-initiation.

CONCLUSIONS

Nearly half of patients with gMG received chronic and multiple IVIg treatment courses within the first year once initiating IVIg treatment, indicating higher usage than expected. For all IVIg initiators, the proportion of patients using corticosteroids and NSISTs did not decrease over 3 years despite IVIg initiation.

A systematic review of population pharmacokinetic analyses of polyclonal immunoglobulin G therapy

BACKGROUND

Population pharmacokinetics (popPK) using the nonlinear mixed-effect (NLME) modeling approach is an essential tool for guiding dose individualization. Several popPK analyses using the NLME have been conducted to characterize the pharmacokinetics of immunoglobulin G (IgG).

OBJECTIVE

To summarize the current information on popPK of polyclonal IgG therapy.

METHOD

A systematic search was conducted in the PubMed and Web of Science databases from inception to December 2020. Additional relevant studies were also included by reviewing the reference list of the reviewed articles. All popPK studies that employed the NLME modeling approach were included and data were synthesized descriptively.

RESULTS

This review included seven studies. Most of the popPK models were developed in patients with primary immunodeficiency (PID). IgG pharmacokinetics was described as a two-compartment model in five studies, while it was described as a one-compartment model in two other studies. Among all tested covariates, weight was consistently identified as a significant predictor for clearance (CL) of IgG. Whereas, weight and disease type were found to be significant predictors for the volume of distribution in central compartment (Vc). In a typical 70 kg adult, the median estimated values of Vc and CL were 4.04 L and 0.144 L/day, respectively. The between subject variability of Vc was considered large. Only two studies evaluated their models using external data.

CONCLUSIONS

Seven popPK studies of IgG were found and discussed, with only weight being a significant covariate across all studies. Future studies linking pharmacokinetics with pharmacodynamics in PID and other patient populations are required.

Chronic immunoglobulin maintenance therapy in myasthenia gravis

BACKGROUND AND PURPOSE

Long-term treatment of myasthenia gravis (MG) includes symptomatic and course-modifying therapies that target the immune system. Recently, both intravenous immunoglobulin (IVIG) and subcutaneous immunoglobulin (SCIG) have emerged as viable options for chronic therapy, considering the favourable safety-efficacy profile and possible immunosuppressant sparing properties. The aim was to investigate the outcomes of the long-term care of generalized MG with immunoglobulin (Ig).

METHODS

This is a retrospective, repeated-measures design study. Charts of generalized MG patients, treated with IVIG/SCIG for at least 6 months, from January 2015 to January 2020, were analysed. The primary outcome was the mean change in Myasthenia Gravis Impairment Index (MGII) after treatment with Ig, comparing baseline to IVIG and SCIG treatment periods. Secondary outcomes included the changes in pyridostigmine, immunosuppressive medications and patient-reported outcome 'percentage of normal' (0%-100%).

RESULTS

Thirty-four patients were treated with chronic Ig therapy (30 IVIG/SCIG, three SCIG, one IVIG). The mean durations of IVIG and SCIG periods were 21.8 ± 19.4 (range 3-64) months and 19.5 ± 11.3 (range 5-45) months respectively. There was a significant reduction in MGII scores (27.7 ± 15.7 baseline; 22.0 ± 17.4 IVIG period; 19.5 ± 18.1 SCIG period; F = 17.9; d.f. = 1.7; P < 0.01), pyridostigmine and immunosuppressant use (P = 0.00). The outcome 'percentage of normal' had a significant positive association with both treatments (P = 0.00).

CONCLUSION

Our study results suggest that patients can be successfully transitioned to IVIG and from IVIG to SCIG in the chronic treatment of generalized MG with reductions in impairments and use of other medications and improvement in overall status with Ig therapy. Prospective, randomized studies are needed to clarify costs and comparative effectiveness.

Maintenance immunosuppression in myasthenia gravis, an update

Therapies for myasthenia gravis (MG) include symptomatic and immunosuppressive/immunomodulatory treatment. Options for immunosuppression include corticosteroids, azathioprine, mycophenolate mofetil, cyclosporine, tacrolimus, methotrexate, rituximab, cyclophosphamide, eculizumab, intravenous immunoglobulin, subcutaneous immunoglobulin, plasmapheresis, and thymectomy. The practical aspects of long-term immunosuppressive therapy in MG are critically reviewed in this article. Application of one or more of these specific therapies is guided based on known efficacy, adverse effect profile, particular disease subtype and severity, and patient co-morbidities.

Intravenous immunoglobulin as monotherapy for myasthenia gravis during pregnancy

INTRODUCTION

Pregnant women with myasthenia gravis (MG) are at increased risk of complications and adverse outcomes, including the teratogenic effects of many drugs used to treat MG women of childbearing age. The effectiveness of intravenous immunoglobulins (IVIg) on other autoimmune mediated diseases has been extensively reported in recent years, although little is known about the role of IVIg in the treatment of MG during pregnancy. We designed this study to determine the effectiveness of IVIg as monotherapy during pregnancy for women with MG.

MATERIAL AND METHODS

Five pregnant MG patients (mean age at delivery 36.4years, SD 5.8, range 29.4-45.2) were studied in 2013-14. Their treatment was switched to monthly IVIg cycles 2months before the pregnancy. Follow-up included monthly neurological QMG throughout the pregnancy and postpartum, obstetrical monitoring during monthly visits in the first two trimesters of the pregnancy, fortnightly visits between week 32 and week 36, and weekly visits after 36weeks, and neonatal follow-up after delivery.

RESULTS

We observed no exacerbations during pregnancy, delivery or post-partum. The mean QMG score at baseline (before pregnancy) was 7.4 points in five women with generalized forms of MG. The maximum mean value reached during pregnancy was 8.6 points. The mean pregnancy duration was 38 w+5 d. No infant with transient neonatal myasthenia gravis.

CONCLUSIONS

These results suggest that monotherapy with IVIg during pregnancy in MG patients could be promising, although confirmation is required in studies with larger populations.

Treatment of myasthenia gravis based on its immunopathogenesis

The prognosis of myasthenia gravis (MG) has improved dramatically due to advances in critical-care medicine and symptomatic treatments. Its immunopathogenesis is fundamentally a T-cell-dependent autoimmune process resulting from loss of tolerance toward self-antigens in the thymus. Thymectomy is based on this immunological background. For MG patients who are inadequately controlled with sufficient symptomatic treatment or fail to achieve remission after thymectomy, remission is usually achieved through the addition of other immunotherapies. These immunotherapies can be classified into two groups: rapid induction and long-term maintenance. Rapid induction therapy includes intravenous immunoglobulin (IVIg) and plasma exchange (PE). These produce improvement within a few days after initiation, and so are useful for acute exacerbation including myasthenic crisis or in the perioperative period. High-dose prednisone has been more universally preferred for remission induction, but it acts more slowly than IVIg and PE, commonly only after a delay of several weeks. Slow tapering of steroids after a high-dose pulse offers a method of maintaining the state of remission. However, because of significant side effects, other immunosuppressants (ISs) are frequently added as "steroid-sparing agents". The currently available ISs exert their immunosuppressive effects by three mechanisms: 1) blocking the synthesis of DNA and RNA, 2) inhibiting T-cell activation and 3) depleting the B-cell population. In addition, newer drugs including antisense molecule, tumor necrosis factor alpha receptor blocker and complement inhibitors are currently under investigation to confirm their effectiveness. Until now, the treatment of MG has been based primarily on experience rather than gold-standard evidence from randomized controlled trials. It is hoped that well-organized studies and newer experimental trials will lead to improved treatments.

Suppression of Experimental Autoimmune Myasthenia Gravis by Intravenous Immunoglobulin and Isolation of a Disease-Specific IgG Fraction

Intravenous immunoglobulin (IVIG) administration has been beneficially used for the treatment of a variety of autoimmune diseases including myasthenia gravis (MG). We have demonstrated that IVIG administration in experimental autoimmune MG (EAMG) results in suppression of disease that is accompanied by decreased Th1 cell and B cell proliferation. Chromatography of pooled human immunoglobulins (IVIGs) on immobilized IgG, isolated from rats with EAMG, results in a complete depletion of the suppressive activity of the IVIG. Moreover, the eluate from this EAMG-specific antibody column retains the immunosuppressive activity of IVIG. This study supports the notion that the therapeutic effect of IVIGs is mediated by an antigen-specific anti-immunoglobulin (anti-idiotypic) activity that is essential for its suppressive activity.

Intravenous immunoglobulin therapy in neurological diseases during pregnancy

Immunological changes during pregnancy influence the course of neurological autoimmune diseases in different ways. In case of pregnancy immunomodulatory standard therapies such as interferon-beta, glatiramer acetate,monoclonal antibodies and cytostatics mostly should be discontinued. In those cases intravenous immunoglobulin (IVIg) therapy might be an alternative. In some diseases, contemporary publications describe positive therapeutic effects on the course of disease during or after pregnancy.

Guidelines on the use of intravenous immune globulin for neurologic conditions

Canada's per capita use of intravenous immune globulin (IVIG) grew by approximately 115% between 1998 and 2006, making Canada one of the world's highest per capita users of IVIG. It is believed that most of this growth is attributable to off-label usage. To help ensure IVIG use is in keeping with an evidence-based approach to the practice of medicine, the National Advisory Committee on Blood and Blood Products (NAC) and Canadian Blood Services convened a panel of national experts to develop an evidence-based practice guideline on the use of IVIG for neurologic conditions. The mandate of the expert panel was to review evidence regarding use of IVIG for 22 neurologic conditions and formulate recommendations on IVIG use for each. A panel of 6 clinical experts, one expert in practice guideline development and 4 representatives from the NAC met to review the evidence and reach consensus on the recommendations for the use of IVIG. The primary sources used by the panel were 2 recent evidence-based reviews. Recommendations were based on interpretation of the available evidence and, where evidence was lacking, consensus of expert clinical opinion. A draft of the practice guideline was circulated to neurologists in Canada for feedback. The results of this process were reviewed by the expert panel, and modifications to the draft guideline were made where appropriate. This practice guideline will provide the NAC with a basis for making recommendations to provincial and territorial health ministries regarding IVIG use management. Recommendations for use of IVIG were made for 14 conditions, including acute disseminated encephalomyelitis, chronic inflammatory demyelinating polyneuropathy, dermatomyositis, diabetic neuropathy, Guillain-Barré syndrome, Lambert-Eaton myasthenic syndrome, multifocal motor neuropathy, multiple sclerosis, myasthenia gravis, opsoclonus-myoclonus, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections, polymyositis, Rasmussen's encephalitis, and stiff person syndrome; IVIG was not recommended for 8 conditions including adrenoleukodystrophy, amyotropic lateral sclerosis, autism, critical illness polyneuropathy, inclusion body, myositis, intractable childhood epilepsy, paraproteinemic neuropathy (IgM variant), and POEMS syndrome. Development and dissemination of evidence-based clinical practice guidelines may help to facilitate appropriate use of IVIG.

Intravenous immunoglobulin suppresses experimental myasthenia gravis: Immunological mechanisms

Intravenous immunoglobulin (IVIG) administration has been beneficially used in the treatment of several autoimmune disorders including myasthenia gravis (MG), although its mechanism of action is still not clear. To study the optimal conditions of IVIG treatment and delineate its mechanism of action we established a suitable model in rat experimental autoimmune MG (EAMG). We show that IVIG has a suppressive effect on the clinical symptoms of ongoing EAMG that is associated with decreased AChR-specific cellular and humoral immune reactivity. Costimulatory factors and cytokine profile analyses suggest that IVIG immunomodulation in EAMG involves suppression of B and Th1-type T cell responses with no generation of T-regulatory cells. Our data contribute to the understanding of the immunological mechanisms underlying IVIG treatment in MG and in other autoimmune disorders.

Immunomodulatory Effects of Intravenous Immunoglobulins as a Treatment for Autoimmune Diseases, Cancer, and Recurrent Pregnancy Loss

Intravenous immunoglobulin (IVIG) is a safe preparation, made of human plasma of thousands of healthy donors. The fascinating history of gamma globulin therapy begins in 1930 when Finland treated pneumococcal pneumonia patients with equine serum, which prolonged their survival from pneumonia. Since then, significant breakthroughs were achieved by Cohn, Bruton, Imbach, and others, whose clinical contribution to the world of medicine was of great importance. Originally IVIG was used to treat immunodeficiencies. Later on the use of IVIG extended to autoimmune diseases as well. The efficacy of IVIG has been established only in several autoimmune diseases; clinical reports of trials, series, and case reports indicate significant improvement in many more autoimmune diseases. IVIG have also showed antimetastatic effects in a variety of cancer cell lines, as well as in a few case reports. The efficiency of IVIG has also been observed in recurrent pregnancy loss (RPL), either as a result of an autoimmune disease or spontaneous. Several attempts were made to discover the immunomodulatory effects of IVIG, but it is still not fully understood. Clearly IVIG has multiple mechanisms of actions, which are thought to cooperate synergistically. One of the main mechanisms of actions of IVIG is its ability to neutralize pathogenic autoantibodies via anti-idiotypic antibodies within IVIG preparation. The ability of IVIG to neutralize pathogenic autoantibodies is of great importance in many autoimmune diseases, as well as in RPL. In cancer cell lines, IVIG modulates the immune system in a few ways, including the induction of IL-12 secretion, which consequently activates natural killer cells, and the induction of expression of proapoptotic genes only in cancer cells. Side effects from IVIG are rare and mostly mild and transient. More importantly adverse effects can be minimized by administration to a selective patient population in a proper way: slow infusion rate of 0.4 g/Kg body weight IVIG for 5 consecutive days, given in monthly cycles. The only downside of IVIG therapy is its high price. Therefore, clinicians should balance efficiency versus cost in deciding whether or not to treat certain conditions with IVIG.

Update on myasthenia gravis

Myasthenia gravis is an autoimmune disorder caused by autoantibodies against the nicotinic acetylcholine receptor on the postsynaptic membrane at the neuromuscular junction and characterised by weakness and fatigability of the voluntary muscles. It has a bimodal peak of incidence with first peak in the third decade and the second peak in the sixth decade. It is probably underdiagnosed in the very old population. Our understanding of the pathogenesis, immunology, and molecular biology of myasthenia gravis has greatly improved in last three decades. It is almost always possible to establish the diagnosis of myasthenia gravis with the current tests. The modern treatment is highly successful and the mortality of treated myasthenia gravis is practically zero. However, there are still important gaps in our knowledge of the origin of myasthenia gravis, the factors that contribute to chronic disease, and the way to cure the disease. In this article the current knowledge of the various aspects of myasthenia gravis are outlined.