Interim analysis of REGAIN study of Soliris (eculizumab) for the treatment of patients with refractory generalized myasthenia gravis .- Alexion Pharmaceuticals.

Alexion Pharmaceuticals, Inc. announced results from an interim analysis of an ongoing Phase III open-label extension study of the pivotal, placebo-controlled REGAIN study of Soliris (eculizumab) for the treatment of patients with refractory generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody-positive. The new results show sustained treatment benefits across a range of MG-specific assessment scales through an additional 52 weeks for patients who continued to receive Soliris, and also demonstrate rapid, significant and sustained improvements through 52 weeks for patients who had crossed over from placebo in REGAIN to Soliris treatment in the extension study.

The safety profile of Soliris was consistent with that observed in the REGAIN study. The results are presented at the annual meeting of the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) in Phoenix, Arizona. Results presented show that the benefits for patients treated with Soliris in REGAIN through 26 weeks were maintained in the extension study across all four assessment scales for an additional 52 weeks (78 weeks in total). For patients who received placebo in REGAIN and then were treated with Soliris in the extension study, significant treatment benefits occurred within 1 to 4 weeks and were sustained through 52 weeks across all four assessment scales.

About REGAIN (MG-301); This was a randomized, double-blind, placebo-controlled, multicenter Phase III clinical study that evaluated the efficacy and safety of Soliris over 26 weeks in 125 patients with refractory gMG who had a confirmed diagnosis of MG with positive serologic test for antibodies against AChR. Patients initially received 900 mg of Soliris or placebo weekly for 4 weeks followed by 1,200 mg of Soliris or placebo 1 week later, and then 1,200 mg of Soliris or placebo every 2 weeks. The primary efficacy endpoint of change from baseline in MG-ADL total score at week 26, as well as the three secondary endpoints —changes from baseline in QMG, MGC, and MG-QoL 15—were assessed using a worst-rank analysis. The study narrowly missed statistical significance on the primary endpoint (p=0.0698). However, 18 out of 22 pre-specified endpoints and analyses showed results with p-values <0.05 across the four assessment scales, supporting early, sustained and substantial responses. The safety profile was consistent with what has been reported for Soliris during the past 10 years in patients with paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS).