Generalized myasthenia gravis (gMG), a chronic autoimmune disease, has long relied on symptomatic and immunosuppressive treatments. However, a significant portion of patients still experience inadequate control, while prolonged corticosteroid use can lead to additional health issues. Complement inhibitors, FcRn antagonists, and B cell-directed therapies are now expanding treatment options, offering more targeted approaches.
Targeted Therapies Bring New Hope, but Safety Remains Key
These new therapies focus on specific components of the autoimmune response, aiming for faster and more sustained disease control. However, they require careful safety management. For instance, complement inhibitors like eculizumab and ravulizumab necessitate meningococcal vaccination due to increased infection risk, particularly from encapsulated bacteria. Similarly, B cell-depleting agents demand rigorous infection screening and monitoring, with contraindications for active infections like hepatitis B and tuberculosis.
The CHAMPION MG trial demonstrated ravulizumab’s significant improvement in MG Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) scores compared to placebo, with benefits observed as early as the first week. This progress highlights the potential of targeted therapies to enhance patient outcomes rapidly.
Balancing Efficacy and Safety in Treatment Decisions
The choice of therapy depends on various factors, including antibody status, disease characteristics, and patient needs. For example, AChR-Ab+ patients may benefit from complement inhibitors, which target the classical complement pathway, while MuSK-Ab+ patients might respond better to B cell-directed therapies that address autoantibody production.
The RAISE trial showed that zilucoplan, a complement inhibitor, provided a 4.39-point improvement in MG-ADL scores at week 12, compared to 2.30 with placebo. This self-administered, once-daily treatment offers a convenient alternative to intravenous options, though it carries additional warnings for pancreatitis and pancreatic cysts, requiring baseline pancreatic enzyme assessment.
As the treatment environment evolves, the focus shifts from broad immunosuppression to more tailored approaches. This shift not only aims to improve disease control but also to minimize treatment-related side effects, offering a better quality of life for gMG patients. Established therapies like pyridostigmine, corticosteroids, and immunosuppressants remain foundational, while intravenous immunoglobulin (IVIg) and plasma exchange (PLEX) continue to play critical roles in managing exacerbations and myasthenic crises.
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The PREVAIL trial for gefurulimab, an investigational C5-targeting nanobody, showed promising results with a 4.2-point improvement in MG-ADL scores at week 26, compared to 2.6 with placebo. This therapy is currently under regulatory review, with potential approval in Europe, and represents a once-weekly subcutaneous option that may further diversify treatment choices.
Expanding Treatment Options for gMG
The development of targeted therapies for generalized myasthenia gravis (gMG) has opened new avenues for treatment. FcRn antagonists, such as efgartigimod and rozanolixizumab, reduce pathogenic autoantibodies by accelerating their breakdown. These therapies have shown significant improvements in MG-ADL scores, with efgartigimod demonstrating a 68% response rate in AChR-Ab+ patients during the ADAPT trial compared to 30% with placebo. Rozanolixizumab also significantly improved MG-ADL scores in the MycarinG trial, while nipocalimab, approved in 2025, showed an average MG-ADL improvement of 4.70 over weeks 22 through 24 in the Vivacity-MG3 trial versus 3.25 with placebo.
B cell-directed therapies, including inebilizumab and rituximab, target the immune cells responsible for autoantibody production. Inebilizumab, approved in 2025, showed a 4.2-point improvement in MG-ADL scores at week 26 in the MINT trial, while also allowing for glucocorticoid tapering. Rituximab, used off-label, is particularly beneficial for MuSK-Ab+ patients with inadequate responses to initial treatments, though it carries significant safety warnings, including risks of severe infusion reactions and infections.
Emerging Therapies and Future Directions
Investigational therapies continue to expand treatment possibilities. Descartes-08, a BCMA-directed CAR T-cell therapy, showed promising results in a phase 2b trial, with 66.7% of patients achieving significant improvements in Myasthenia Gravis Composite scores, maintained through 12 months in many patients.
Other mechanisms, such as BTK inhibition, are also under investigation. The oral BTK inhibitor remibrutinib is being evaluated in the phase 3 RELIEVE trial. Additionally, imeroprubart (IMVT-1402), another FcRn-targeting monoclonal antibody, is in phase 3 trials, further broadening the FcRn antagonist class. As these therapies progress, long-term and comparative data will be key to determine their optimal use, sequencing, and potential to reduce reliance on broad immunosuppression.