Safety of Eculizumab in Nmosd and MG – Analysis of the Phase 3 Studies Prevent and Regain and Their Extensions

Background: Aquaporin-4 immunoglobulin G-positive neuromyelitis optica spectrum disorder (AQP4+ NMOSD) and acetylcholine receptor antibody-positive generalized myasthenia gravis (AChR+ gMG) are neurological disorders with complement involvement. Eculizumab (a terminal complement inhibitor) demonstrated efficacy in reducing relapse risk and in eliciting clinical improvements during the phase 3, randomized, double-blind PREVENT and REGAIN studies and their open-label extensions (OLEs) (NCT01892345/NCT02003144 [interim data, July 2019] and NCT01997229/NCT02301624) previously published.

Objectives: To compare infection rates in patients with AQP4+ NMOSD or AChR+ gMG receiving eculizumab or placebo with or without concomitant immunosuppressive therapy (IST) during PREVENT, REGAIN and their OLEs.

Methods: Patients were randomized to eculizumab (maintenance dose, 1200 mg/2 weeks) or placebo. Concomitant ISTs, excluding rituximab, were permitted. Post hoc analysis was performed to examine rates of infections in these studies and for subgroups determined by number of ISTs received at baseline.

Results: Rates/100 patient-years (PY) and types of infection were similar in eculizumab and placebo groups. In patients with NMOSD, rates/100 PY and % (n/N), respectively, were: no IST: 176.1, 80.0% (28/35) vs 192.2, 61.5% (8/13); 1 IST: 171.5, 81.8% (45/55) vs 154.1, 63.6% (14/22); 2 ISTs: 186.7, 85.1% (40/47) vs 238.2, 83.3% (10/12). For patients with gMG, rates/100 PY and % (n/N), respectively, were: no IST: 236.8, 100.0% (2/2) vs 305.6, 50.0% (1/2); 1 IST: 228.8, 82.9% (34/41) vs 253.1, 50.0% (9/18); 2 ISTs: 170.5, 91.0% (71/78) vs 192.5, 58.5% (24/41); ≥ 3 ISTs: 97.5, 50.0% (1/2) vs 100.1, 50.0% (1/2). In patients with NMOSD or gMG receiving eculizumab vs placebo, serious infection rates/100 PY and % (n/N), respectively, were: no IST: 2.3, 5.7% (2/35) vs 8.0, 7.7% (1/13) and none observed (0/2 vs 0/2); 1 IST: 11.2, 16.4% (9/55) vs 7.0, 9.1% (2/22) and 16.2, 24.4% (10/41) vs 34.5, 5.6% (1/18); 2 ISTs: 14.8, 29.8% (14/47) vs 47.6, 25.0% (3/12) and 13.4, 21.8% (17/78) vs 24.1, 12.2% (5/41); ≥ 3 ISTs (gMG only): 13.9, 50.0% (1/2) vs 0.0, 0.0% (0/2). One patient with gMG (2 ISTs) had meningococcal meningitis that resolved with antibiotics and eculizumab was resumed.

Conclusions: In AQP4+ NMOSD and AChR+ gMG, infection rates/100 PY were similar in eculizumab and placebo groups, regardless of concomitant IST. Infection rates/100 PY were consistent with the established safety profile of eculizumab.