Two steps forward, one step back: Mycophenolate mofetil treatment for myasthenia gravis in the united states

Mycophenolate mofetil reduces the risk of relapse in anti-leucine-rich glioma-inactivated protein 1 encephalitis: a prospective observational cohort study

BACKGROUND

Mycophenolate mofetil (MMF) is frequently used in the treatment of neurological autoimmune disorders. However, its effect on the relapse risk in anti-leucine-rich glioma-inactivated protein 1 (anti-LGI1) encephalitis is not well studied.

METHODS

In this prospective observational cohort study, anti-LGI1 encephalitis patients were grouped according to MMF treatment status (MMF and non-MMF groups). The primary outcome was relapse after disease onset.

RESULTS

A total of 83 patients were included, with a median onset age of 60 years. Fifty-four patients were men (65.1%). The MMF group comprised 28 patients and the non-MMF group comprised 55. Median follow-up from symptom onset was 26 months. Relapse occurred in 43 patients (51.8%). Median modified Rankin scale (mRS) score at enrollment was significantly higher in the MMF group than the non-MMF group (3 vs. 2; p = 0.001). Median mRS score at last follow-up was comparable between groups (1 vs. zero; p = 0.184). Both MMF treatment (HR 0.463; 95% CI, 0.231-0.929; p = 0.030) and cognitive impairment at enrollment (HR 3.391; 95% CI, 1.041-11.044; p = 0.043) were independent predictors of relapse. Starting immunotherapy before development of cognitive impairment trended towards reducing relapse risk. Outcome at last follow-up was good (mRS score 0-2) in all patients except for one in the non-MMF group. Adverse events associated with MMF treatment were mild and transient.

CONCLUSION

Although the outcome of anti-LGI1 encephalitis patients is generally favorable, relapse is common, especially in those with cognitive impairment. MMF treatment is well-tolerated and can significantly reduce the risk of relapse.

Current Treatment of Myasthenia Gravis

Myasthenia gravis (MG) is the most extensively studied antibody-mediated disease in humans. Substantial progress has been made in the treatment of MG in the last century, resulting in a change of its natural course from a disease with poor prognosis with a high mortality rate in the early 20th century to a treatable condition with a large proportion of patients attaining very good disease control. This review summarizes the current treatment options for MG, including non-immunosuppressive and immunosuppressive treatments, as well as thymectomy and targeted immunomodulatory drugs.

Progress in the therapy of myasthenia gravis: getting closer to effective targeted immunotherapies

PURPOSE OF REVIEW

To provide an update on immunomodulating and immunosuppressive therapies in myasthenia gravis and highlight newly approved, or pending approval, therapies with new biologics.

RECENT FINDINGS

Preoperative IVIg is not needed to prevent myasthenic crisis in stable myasthenia gravis patients scheduled for surgery under general anesthesia, based on controlled data. Rituximab, if initiated early in new-onset myasthenia gravis, can lead to faster and more sustained remission even without immunotherapies in 35% of patients at 2 years. Biomarkers determining the timing for follow-up infusions in Rituximab-responding AChR-positive patients are discussed. Most patients with MuSK-positive myasthenia gravis treated with Rituximab have sustained long-term remission with persistent reduction of IgG4 anti-MuSK antibodies. Eculizumb in the extension REGAIN study showed sustained long-term pharmacological remissions and reduced exacerbations. Three new biologic agents showed promising results in phase-II controlled myasthenia gravis trials: Zilucoplan, a subcutaneous macrocyclic peptide inhibiting complement C5; Efgartigimod, an IgG1-derived Fc fragment binding to neonatal FcRn receptor; and Rozanolixizumab, a high-affinity anti-FcRn monoclonal antibody. Finally, the safety of ongoing myasthenia gravis immunotherapies during COVID19 pandemic is discussed.

SUMMARY

New biologics against B cells, complement and FcRn receptor, are bringing us closer to successful targeted immunotherapies in the chronic management of myasthenia gravis promising an exciting future for antibody-mediated neurological diseases.

History of Myasthenia Gravis Revisited

The first description of myasthenia gravis (MG) was given by Thomas Willis in 1672. MG was the focus of attention after mid-nineteenth century and a great amount of information has been accumulated in a span of 150 years. The aim of this review is to convey this information according to a particular systematic and to briefly relate the experience of Istanbul University. MG history was examined in four periods: 1868-1930, 1930-1960, 1960-1990, and 1990-2020. In the first period (1868-1930), all the clinical characteristics of MG were defined. Physiological/pharmacological studies on the transmission at the neuromuscular junction were initiated, and the concept of repetitive nerve stimulation emerged. A toxic agent was believed to be the cause of MG which appeared to resemble curare intoxication. Association of MG with thymus was noticed. No noteworthy progress was made in its treatment. In the second period (1930-1960), acetylcholine was discovered to be the transmitter at the neuromuscular junction. Repetitive nerve stimulation was used as a diagnostic test. The autoimmune nature of MG was suspected and experiments to this end started to give results. The hallmark of this period was the use of anticholinesterases and thymectomy in the treatment of MG. The third period (1960-1990) can probably be considered a revolutionary era for MG. Important immunological mechanisms (acetylcholine receptor isolation, discovery of anti-acetylcholine receptor antibodies) were clarified and the autoimmune nature of MG was demonstrated. Treatment modalities which completely changed the prognosis of MG, including positive pressure mechanic ventilation and corticosteroids as well as plasma exchange/IVIg and azathioprine, were put to use. In the fourth period (1990-2020), more immunological progress, including the discovery of anti-MuSK antibodies, was achieved. Videothoracoscopic thymectomy reduced the morbidity and mortality rate associated with surgery. New drugs emerged and clinical trials were performed. Valuable guidelines were published. In the last part of the review, the experience in MG of Istanbul University, a pioneer in Turkey, is related.

From Traditional to Targeted Immunotherapy in Myasthenia Gravis: Prospects for Research

Treatment of Myasthenia Gravis (MG) is still based on non-specific immunosuppression. Long-term high dose corticosteroids is still a major cause of side effects, in young as well as in elderly patients in whom comorbidities further increase the burden of chronic immunosuppression. Moreover, awareness of the limits of traditional therapies has led to the concept of “refractory MG.” The therapeutic approach to MG is therefore progressively evolving from the classic combination of corticosteroids and immunosuppressive drugs to new biological compounds targeting different immunopathological steps. Killing of B cells with Rituximab has been proposed and tested with positive results, particularly in patients with MuSK-associated MG. Therapeutic monoclonals against B cells at different stages of their maturation, or against molecules involved in B cell activation and function, represent a new area for further investigation. A differently targeted approach involved Eculizumab, a monoclonal antibody preventing the formation of C59b-induced MAC causing destruction of the neuromuscular junction. Data from clinical trials led to the approval of Eculizumab in the United States and Europe for MG. Since Eculizumab is a complement-targeted therapy, its use is limited to anti-acetylcholine receptor-associated MG, since anti-MuSK antibodies belong to IgG4 subclass and do not fix complement. Several anti-complement compounds are under investigation. An even more recent approach is the interference with the neonatal Fc receptor leading to a rapid reduction of circulating IgGs and hence of specific autoantibodies, an approach suitable for both anti-acetylcholine- and MuSK-associated MG. The investigation of compounds that selectively target the immune system will stimulate the search for specific biomarkers of disease activity and response to treatment, setting the basis for personalized medicine in MG.

Immunotherapy in myasthenia gravis in the era of biologics

No consensus has been reached on the ideal therapeutic algorithm for myasthenia gravis (MG). Most patients with MG require induction therapy with high doses of corticosteroids and maintenance with an immunosuppressant. Severe cases and acute worsening require intravenous immunoglobulin or plasmapheresis before oral immunosuppressants start having an effect. However, biologics are emerging as important therapeutic tools that promise to provide better corticosteroid sparing effects than standard treatments and can even induce remission. In particular, eculizumab, a monoclonal antibody against complement C5, has been approved by the FDA for refractory MG on the basis of a phase III trial. Rituximab, an anti-CD20 monoclonal antibody that depletes peripheral B cells, has also been effective in many large uncontrolled series, although was not in a small phase III trial. Whether the newer anti-CD20 agents ocrelizumab, ofatumumab, obinutuzumab, ublituximab or inebilizumab will be more effective remains unclear. Belimumab, an antibody against the B cell trophic factor BAFF, was ineffective in phase III trials, and efgartigimod, which depletes antibodies, was effective in a phase II study. Some anti-cytokine agents relevant to MG immunopathogenesis also seem promising. Checkpoint inhibitors can trigger MG in some patients, necessitating early intervention. Increased availability of new biologics provides targeted immunotherapies and the opportunities to develop more specific therapies.

Pharmacological treatment other than corticosteroids, intravenous immunoglobulin and plasma exchange for Guillain-Barré syndrome

BACKGROUND

Plasma exchange and intravenous immunoglobulin, but not corticosteroids, are beneficial in Guillain-Barré syndrome (GBS). The efficacy of other pharmacological agents is unknown. This review was first published in 2011 and previously updated in 2013, and 2016.

OBJECTIVES

To assess the effects of pharmacological agents other than plasma exchange, intravenous immunoglobulin and corticosteroids for GBS.

SEARCH METHODS

On 28 October 2019, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, and Embase for treatments for GBS. We also searched clinical trials registries.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) or quasi-RCTs of acute GBS (within four weeks from onset) of all types and degrees of severity, and in individuals of all ages. We discarded trials that investigated only corticosteroids, intravenous immunoglobulin or plasma exchange. We included other pharmacological treatments or combinations of treatments compared with no treatment, placebo or another treatment.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

We found six trials of five different interventions eligible for inclusion in this review. The trials were conducted in hospitals in Canada, China, Germany, Japan and the UK, and included 151 participants in total. All trials randomised participants aged 16 years and older (mean or median age in the trials ranged from 36 to 57 years in the intervention groups and 34 to 60 years in the control groups) with severe GBS, defined by the inability to walk unaided. One trial also randomised patients with mild GBS who were still able to walk unaided. We identified two new trials at this update.The primary outcome measure for this review was improvement in disability grade four weeks after randomisation. Four of six trials had a high risk of bias in at least one respect. We assessed all evidence for the outcome mean improvement in disability grade as very low certainty, which means that we were unable to draw any conclusions from the data. One RCT with 19 participants compared interferon beta-1a (IFNb-1a) and placebo. It is uncertain whether IFNb-1a improves disability after four weeks (mean difference (MD) -0.1; 95% CI -1.58 to 1.38; very low-certainty evidence). A trial with 10 participants compared brain-derived neurotrophic factor (BNDF) and placebo. It is uncertain whether BDNF improves disability after four weeks (MD 0.75; 95% CI -1.14 to 2.64; very low-certainty evidence). A trial with 37 participants compared cerebrospinal fluid (CSF) filtration and plasma exchange. It is uncertain whether CSF filtration improves disability after four weeks (MD 0.02; 95% CI -0.62 to 0.66; very low-certainty evidence). One trial that compared the Chinese herbal medicine tripterygium polyglycoside with corticosteroids with 43 participants did not report the risk ratio (RR) for an improvement by one or more disability grade after four weeks, but did report improvement after eight weeks. It is uncertain whether tripterygium polyglycoside improves disability after eight weeks (RR 1.47; 95% CI 1.02 to 2.11; very low-certainty evidence). We performed a meta-analysis of two trials comparing eculizumab and placebo with 41 participants. It is uncertain whether eculizumab improves disability after four weeks (MD -0.23; 95% CI -1.79 to 1.34; very low-certainty evidence). Serious adverse events were uncommon in each of the trials and evidence was graded as either low or very low. It is uncertain whether serious adverse events were more common with IFNb-1a versus placebo (RR 0.92, 95% CI 0.23 to 3.72; 19 participants), BNDF versus placebo (RR 1.00, 95% CI 0.28 to 3.54; 10 participants) or CSF filtration versus plasma exchange (RR 0.13, 95% CI 0.01 to 2.25; 37 participants). The trial of tripterygium polyglycoside did not report serious adverse events. There may be no clear difference in the number of serious adverse events after eculizumab compared to placebo (RR 1.90, 0.34 to 10.50; 41 participants). We found no clinically important differences in any of the outcome measures selected for this review in any of the six trials. However, sample sizes were small and therefore clinically important benefit or harm cannot be excluded.

AUTHORS' CONCLUSIONS

All six RCTs were too small to exclude clinically important benefit or harm from the assessed interventions. The certainty of the evidence was low or very low for all interventions and outcomes.

[Myasthenia gravis]

Myasthenia gravis (MG) is an autoimmune disorder caused by antibodies against acetylcholine receptors (AChR) or other structural proteins of the neuromuscular junction. This diminishes cholinergic transmission, thus leading to exercise-induced fatigue and sometimes manifest muscle weakness, including the bulbar and ocular musculature. Whereas ocular MG is as a rule initially symptomatically treated with acetylcholine esterase inhibitors, generalized MG requires long-term immunosuppression. The thymus plays a particular role in the pathophysiology of AChR antibody-positive MG, which can also manifest as a paraneoplastic disorder in the context of a thymoma. This article reviews the basic and advanced treatment options of the different disease subtypes including plasma exchange and immunoglobulins for treatment in a myasthenic crisis. Recently, clinical approval of eculizumab, a complement inhibitor, enriched the pharmacological armamentarium for AChR antibody-positive MG patients not appropriately responding to immunosuppression alone.

Ocular myasthenia gravis: an update on diagnosis and treatment

PURPOSE OF REVIEW

Myasthenia gravis is an autoimmune disease that commonly affects the palpebral and extraocular muscles. Ocular myasthenia gravis (OMG) is a variant of the disease that is confined to the ocular muscles but frequently becomes generalized over time. The diagnosis of OMG is often challenging but both clinical and laboratory findings are helpful in confirming the clinical suspicion. This review provides an update on the diagnostic approach and therapeutic options for OMG.

RECENT FINDINGS

Antimuscle-specific tyrosine kinase and LDL-related receptor-related protein 4 are newly available serologic testing for myasthenia gravis that can help in increasing the diagnostic sensitivity of OMG. They should be included to the diagnostic algorithm of OMG in appropriate clinical situations.

SUMMARY

OMG remains a primarily clinical diagnosis, but recent advances in laboratory testing can improve the diagnostic accuracy and should be used in appropriate clinical settings. The mainstay of treatment for OMG has not significantly changed over the past years, but the increasing availability of steroid-sparing agents improved the disease control while minimizing steroid-induced complications.

Pharmacological treatment other than corticosteroids, intravenous immunoglobulin and plasma exchange for Guillain-Barré syndrome

BACKGROUND

Plasma exchange and intravenous immunoglobulin, but not corticosteroids, are beneficial in Guillain-Barré syndrome (GBS). The efficacy of other pharmacological agents is unknown. This review was first published in 2011 and updated in 2013 and 2016.

OBJECTIVES

To assess the effects of pharmacological agents other than plasma exchange, intravenous immunoglobulin and corticosteroids for GBS.

SEARCH METHODS

On 18 January 2016, we searched the Cochrane Neuromuscular Specialised Register, Cochrane Central Register of Controlled Trials, MEDLINE, and Embase for treatments for GBS. We also searched clinical trials registries.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) or quasi-RCTs of acute GBS (within four weeks from onset) of all types and degrees of severity, and in individuals of all ages. We discarded trials that investigated only corticosteroids, intravenous immunoglobulin or plasma exchange. We included other pharmacological treatments or combinations of treatments compared with no treatment, placebo or another treatment. We also identified a number of non-randomised studies during the search, the results of which we considered in the Discussion.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

We identified no new trials during this update of the review. In previous versions of this review we identified only very low quality evidence for four different interventions published in four studies. Each study had a high risk of bias in at least one respect. One RCT with 19 participants comparing interferon beta-1a and placebo showed no clinically important difference in any outcome between groups. Another with 10 participants comparing brain-derived neurotrophic factor and placebo showed no clinically important difference in any outcome between groups. A third with 37 participants comparing cerebrospinal fluid filtration and plasma exchange also showed no clinically important difference in any outcome between groups. In a fourth with 43 participants, the risk ratio for an improvement by one or more disability grade after eight weeks was greater with the Chinese herbal medicine tripterygium polyglycoside than with corticosteroids (risk ratio 1.47; 95% confidence interval 1.02 to 2.11); other outcomes in this trial showed no difference. Serious adverse events were uncommon with each of these treatments and in the control groups.

AUTHORS' CONCLUSIONS

The quality of the evidence was very low. Three small RCTs, comparing interferon beta-1a or brain-derived neurotrophic factor with placebo, and cerebrospinal fluid filtration with plasma exchange, showed no significant benefit or harm for any of the interventions. A fourth small trial showed that the Chinese herbal medicine, tripterygium polyglycoside, hastened recovery in people with GBS to a greater extent than corticosteroids, but this result needs confirmation. We were unable to draw any useful conclusions from the few observational studies we identified.

Overcoming challenges in the diagnosis and treatment of myasthenia gravis

In recent years, the discovery of new autoantigens and the use of sensitive assays have expanded the clinical spectrum of myasthenia gravis (MG). In particular, antibodies binding to clustered acetylcholine receptors and to the low-density lipoprotein receptor-related protein 4 have not only bridged a significant gap in diagnosis but also have relevant clinical implications. MG management includes different therapeutic options, from symptomatic agents as the only therapy in mildly affected cases to combined long-term immunosuppression and thymectomy in patients with severe disabling disease. MG biological diversity can influence the response to therapies and should be taken into account when planning treatment. Biologic agents are promising, though their use is currently limited to patients with refractory disease.