In patients with refractory generalized myasthenia gravis (MG) with anti-acetylcholine receptor positive (AChR +), treatment with eculizumab, a humanized monoclonal antibody that binds to human C5 complement protein, was associated with rapid and sustained clinical response, according to study results published in Neurology.
While immunosuppressive therapies are effective for most patients with MG, up to 15% show an inadequate response and are considered refractory MG. An interim analysis of the REGAIN study (ClinicalTrials.gov Identifier: NCT01997229) showed that the benefits of eculizumab were retained for 3 years in patients with refractory generalized AChR + MG.
The aim of the current study was to publish the final efficacy data of eculizumab in patients with refractory generalized MG during REGAIN and through open week 130 using the Myasthenia Gravis Foundation of America (MGFA). Post-intervention MGFA status can be used to assess changes in a patient’s condition after treatment. This includes improvement, deterioration, or no change in clinical manifestations prior to treatment.
The analysis included 117 patients who had completed the REGAIN study and continued the open extension (ClinicalTrials.gov Identifier: NCT02301624). Of these, 56 participants in the REGAIN study were treated with eculizumab and continued the active medication in the open label extension. 61 participants received a placebo during the REGAIN study and switched to eculizumab in the open label study.
At week 26, improved status was more common with eculizumab compared with placebo (60.7% versus 41.7%), while 1 eculizumab-treated patient and 5 placebo-treated patients reported worsening. A larger proportion of eculizumab-treated patients than placebo achieved MGFA status with minimal manifestations after the intervention (25.0% versus 13.3%; common odds ratio 2.3; 95% CI: 1.1-4.5 ).
At week 130 of the open-label study, the results showed an improved status in most patients in both groups: 80 percent of patients treated with eculizumab and continued in the open-label extension, compared with 94.3% of patients who switched from placebo to eculizumab. At this point, 57.1% of patients achieved post-intervention MGFA status with minimal manifestations.
The safety profile of eculizumab was consistent with the known profile. Study researchers reported no new safety signals. The most common adverse events with eculizumab were headache (44.4%) and nasopharyngitis (38.5%). MG and MG crisis worsening reported in 15.4% and 3.4% of patients, respectively, was the most common serious adverse event.
The open design of the extension study was the main limitation of this analysis.
“These results support the long-term effectiveness of eculizumab in patients with AChR + [anti-acetylcholine receptor-positive] fireproof GMG [generalized MG]”Concluded the study researchers.
Disclosure: This clinical study was supported by Alexion Pharmaceuticals. For a full list of the authors’ information, see the original reference.
Mantegazza R., Wolfe GI, Muppidi S. et al. Post-intervention status in patients with refractory myasthenia gravis treated with eculizumab during REGAIN and its open-label extension. Neurology. Published online on November 23, 2020. doi: 10.1212 / WNL.0000000000011207