Efgartigimod produced a significantly greater improvement than placebo in patients with autoimmune myositis in the Phase 3 ALKIVIA trial, according to results announced by argenx SE and shared on NASDAQ.

At Week 52, participants in the combined immune-mediated necrotizing myopathy (IMNM) and dermatomyositis population had an average Total Improvement Score of 48.0 with efgartigimod, compared with 32.6 with placebo—a 15.4-point difference (p=0.0011). The trial also met key secondary endpoints measuring response rate, time to response, muscle strength and disease activity. Treatment was generally well tolerated.

In the IMNM group, the average score improved by 45.1 points with efgartigimod versus 30.2 with placebo, a 14.8-point difference (p=0.0048). Argenx said it plans to submit a supplemental Biologics License Application to the U.S. Food and Drug Administration for efgartigimod in IMNM by the end of 2026.

Among participants with dermatomyositis, the difference in average improvement was 14.5 points: 51.5 with efgartigimod versus 37.0 with placebo. However, this smaller cohort did not reach statistical significance (p=0.1093).

This article summarizes results reported by argenx SE; the company announcement did not provide additional trial-design details in the supplied material.