Efficacy and safety of iscalimab, a novel anti-CD40 monoclonal antibody, in moderate-to-severe myasthenia gravis: A phase 2 randomized study

BACKGROUND: Increased morbidity in many patients with myasthenia gravis (MG) on long-term immunosuppression highlights the need for improved treatments. The aim of this study is to investigate the safety and efficacy of iscalimab (CFZ533), a fully human anti-CD40 monoclonal antibody, in patients with moderate-to-severe MG receiving standard-of-care (SoC) therapies.

METHODS: In this double-blind, placebo-controlled phase 2 study, symptomatic patients (n = 44) despite SoC were randomized 1:1 to receive intravenous iscalimab (10 mg/kg; n = 22) or placebo (n = 22) every 4 weeks for 6 doses in total. Patients were followed up for 6 months after the last dose. The total duration of the study was 52 weeks.

RESULTS: In total, 34 of 44 patients (77.3 %) completed the study. The primary endpoint, Quantitative MG score, did not change significantly between baseline and week 25 for iscalimab (median [90 % CI], -4.07 [-5.67, -2.47]) versus placebo (-2.93 [-4.53, -1.33]); however, non-thymectomized patients (n = 29) showed more favorable results (iscalimab, -4.35 [-6.07, -2.64] vs placebo, -2.26 [-4.16, -0.36]). A statistically significant difference between iscalimab and placebo groups was observed in MG Composite score (adjusted mean change: -4.19 [-6.67, -1.72]; p = 0.007) at week 13, and MG-Activities of Daily Living score (-1.93 [-3.24, -0.62]; p = 0.018) at week 21. Adverse events were comparable between the iscalimab (91 %) and placebo (96 %) groups.

CONCLUSION: Iscalimab showed favorable safety and improvements compared with placebo in non-thymectomized patients with moderate-to-severe MG. It did not show any protective effect in patients with moderate-to-severe MG.