GLPG3667 - (GALACELA)

December 18, 2025: Galapagos NV (Euronext & Nasdaq: GLPG) reported topline results from two Phase 3‑enabling, randomized, double‑blind, placebo‑controlled studies of GLPG3667 (selective TYK2 inhibitor) in dermatomyositis (DM) and systemic lupus erythematosus (SLE).

DM (GALARISSO; NCT05695950): The study met its primary endpoint. GLPG3667 150 mg once daily plus standard of care (N=21) showed a statistically significant benefit vs placebo (N=19) on Total Improvement Score (TIS) at Week 24 (p=0.0848; Δ 14.26), using a pre-specified significance threshold of α=0.1. Secondary endpoints including TIS20/40/60 and m‑CDASI‑A improved versus placebo. Safety/tolerability were favorable over 24 weeks; patients could enter a 24‑week extension where all receive 150 mg.

SLE (GALACELA; NCT05856448): The primary endpoint (dose-response on SRI‑4 at Week 32) was not statistically significant for 75 mg (N=59) and 150 mg (N=64) vs placebo (N=63), though numerical improvements were seen on several secondary endpoints, particularly skin outcomes. The trial continues; final Week 48 data are expected in Q2 2026.

Galapagos said it will evaluate strategic alternatives, including resuming partnering; Gilead temporarily waived certain rights to enable external partnership discussions. Data are planned for an upcoming medical conference.