Phase 3 Results for Eculizumab for Treatment of Patients with Myasthenia Gravis
At the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) in Washington, DC, October 10-12, results were presented from the phase 3 REGAIN trial (NCT01997229) and the REGAIN open-label extension (NCT02301624) for eculizumab (Alexion; Boston, MA) for treatment of patients with myasthenia gravis (MG).
For the REGAIN study, clinical improvement for patients with refractory generalized anti-acetylcholine receptor positive (AChR+) MG was measured with patient reported outcomes using the MG activities-of-daily-living (MG-ADL) and MG quality-of-life 15 (MGQOL15) questionnaires. Physician-reported quantitative myasthenia gravis (QMG) tests were also performed. Minimal symptom expression was defined as scores of 01 on the MG-ADL or an MG-QOL15 total score of 0-3.
After enrollment, 125 patients were randomly assigned to receive eculizumab (n = 63) or placebo (n = 62) for 26 weeks after which time patients could enroll in an open-label extension study and continue or begin receiving eculizumab. After 26 weeks of treatment, patients treated with eculizumab had improvements in bulbar (P = .0682), respiratory (P = .0682), gross motor (P = .0114), and ocular (P = .0017) domains compared to those treated with placebo; these differences were statistically significant for gross motor and ocular domains only. More patients treated with eculizumab achieved minimal symptom expression (21.4% MG-ADL, 16.1% MGQOL15) compared to those treated with placebo (1.7% MG-ADL, 1.7% MGQOL15) (95% CI: 8.5-31, 4.2-24.5, respectively). During a subsequent 26 weeks of open-label extension treatment, 23.6% of patients who switched to eculizumab had minimal symptoms on MG-ADL and 12.5% had minimal symptoms on MGQOL15. Similar proportions of patients who remained on eculizumab treatment for weeks 27-52 had minimal symptom expression.
Eculizumab treatment was associated with a 65% reduction in exacerbation rate (P = .0057), a 71% reduction in hospitalizations (P = .0316) and a 66% reduction in rescue therapy use (P = .0072) versus placebo. Compared with the pre-study year, eculizumab was associated with reductions of 74% in exacerbation rate and 83% in hospitalizations (both P < .0001).