argenx: Positive Phase 3 ALKIVIA results for efgartigimod in autoimmune myositis
- ALKIVIA Phase 3 met primary endpoint: 15.4‑point greater mean TIS at Week 52 vs placebo in combined IMNM+DM population (47.95 vs 32.56; p=0.0011).
- Treatment effect appeared by Week 4 and was sustained through 52 weeks despite protocol-mandated steroid tapering.
- IMNM subgroup: 14.8‑point TIS improvement vs placebo (45.05 vs 30.24; p=0.0048); DM subgroup: 14.5‑point improvement (51.51 vs 36.96) but not statistically significant (p=0.1093).
- Efgartigimod was well tolerated with a safety profile consistent with prior studies; all six TIS core measures favored active treatment, including skin improvement in DM.
Topline efficacy
The ALKIVIA Phase 3 study showed that subcutaneous efgartigimod produced a statistically significant and clinically meaningful improvement in mean Total Improvement Score (TIS) at 52 weeks versus placebo in the combined immune‑mediated necrotizing myopathy (IMNM) and dermatomyositis (DM) population (47.95 vs 32.56; 15.4‑point difference; p=0.0011).
Onset and durability
Separation from placebo emerged by Week 4 and was maintained through the one‑year treatment period, despite a protocol‑mandated corticosteroid taper, indicating a rapid and sustained treatment effect.
Subtype and clinical measures
Prespecified analyses found a significant benefit in IMNM (14.8‑point TIS advantage; 45.05 vs 30.24; p=0.0048). A similar magnitude of improvement occurred in DM (14.5‑point advantage; 51.51 vs 36.96) but did not reach statistical significance in that smaller cohort (p=0.1093). All six TIS core set measures contributed to the effect, covering muscle strength, physical function and extramuscular disease activity, with skin improvement observed in DM.
Safety, design and next steps
Efgartigimod was well tolerated with a safety profile consistent with prior studies. ALKIVIA was a global randomized, double‑blind, placebo‑controlled Phase 2/3 program that enrolled 264 patients overall (Phase 3 n=175) and included a mandated steroid taper. Detailed results will be presented at a forthcoming medical meeting, and efgartigimod continues to be evaluated in other autoimmune rheumatologic indications.
Source: argenx