From the Guidelines
Rituximab is generally considered more efficient than eculizumab for the treatment of myasthenia gravis (MG) due to its broader effectiveness across MG subtypes, established safety profile, and lower cost. Rituximab, typically administered at 375 mg/m² weekly for 4 weeks or 1000 mg given twice two weeks apart, targets B cells and has shown effectiveness particularly in MuSK-positive MG, with benefits often seen within 1-3 months and lasting 6-12 months or longer 1. In contrast, eculizumab, given as 900 mg weekly for 4 weeks followed by 1200 mg every 2 weeks, inhibits complement activation and is FDA-approved specifically for acetylcholine receptor antibody-positive generalized MG patients who are refractory to conventional therapies. While eculizumab is being studied for its potential use in other conditions, such as Guillain-Barré syndrome, its use in MG is more limited compared to rituximab 1. Treatment choice should be individualized based on MG subtype, antibody status, disease severity, and patient-specific factors. Both medications require careful monitoring for infusion reactions and increased infection risk, and patients should receive appropriate vaccinations before starting therapy.
Some key points to consider when choosing between rituximab and eculizumab for MG treatment include:
- MG subtype: Rituximab has shown effectiveness in MuSK-positive MG, while eculizumab is FDA-approved for acetylcholine receptor antibody-positive generalized MG
- Antibody status: Patients with certain antibody profiles may respond better to one medication over the other
- Disease severity: Patients with more severe disease may require more aggressive treatment, such as rituximab
- Patient-specific factors: Patients with certain comorbidities or contraindications may be more suitable for one medication over the other
Overall, while both medications have their place in the treatment of MG, rituximab is generally the preferred choice due to its broader effectiveness and established safety profile 1.
From the Research
Comparison of Rituximab and Eculizumab for Myasthenia Gravis (MG)
- The efficacy of rituximab and eculizumab in treating MG has been compared in several studies 2, 3, 4, 5, 6.
- A retrospective observational study found that eculizumab was associated with a better outcome compared to rituximab in patients with generalized, therapy-refractory anti-acetylcholine receptor antibody (anti-AChR-ab)-mediated MG 2.
- The study measured the change in the quantitative myasthenia gravis (QMG) score at 12 and 24 months of treatment and found that eculizumab-treated patients had a better outcome than rituximab-treated patients.
Eculizumab Efficacy in Refractory MG
- Eculizumab has been shown to be effective in treating refractory generalized myasthenia gravis (gMG) with anti-AChR antibodies 3, 4, 5, 6.
- A phase 3, randomized, double-blind, placebo-controlled, multicenter study (REGAIN) found that eculizumab was well tolerated, but the primary analysis showed no significant difference between eculizumab and placebo in terms of change in MG-ADL total score 3.
- However, a subgroup analysis of the REGAIN study and its extension study found that eculizumab was effective in patients with refractory anti-AChR+ gMG previously treated with rituximab 6.
Safety and Tolerability
- Eculizumab has been shown to be well tolerated in patients with refractory gMG, with a safety profile consistent with its established profile 3, 6.
- The most common adverse events reported in clinical trials were headache and upper respiratory tract infection 3.
- Myasthenia gravis exacerbations were reported in some patients, but the risk of myasthenic crisis was not ameliorated in either group 2, 3.