Ascletis' ASC50 Cuts PASI 48.9% in Phase 1 Psoriasis Trial; Shares Dip 0.18%

Ascletis Pharma Inc. (1672.HK) reported positive Phase 1 results for its oral psoriasis candidate ASC50, showing a 48.9% placebo-adjusted reduction in PASI score after 28 days of once-daily 200 mg dosing in mild-to-moderate plaque psoriasis patients. Shares fell 0.18% to HK$8.53 in Hong Kong trading on September 29, 2026. The randomized, placebo-controlled trial found the placebo-adjusted PASI reduction deepened to 60.7% six days after the last dose and 65.9% at 15 days, with a steady-state elimination half-life of 6.5 days — supporting potential once-weekly oral dosing. ASC50, an IL-17A small-molecule inhibitor, showed target engagement via elevated plasma IL-17A. All adverse events were mild (Grade 1) and transient, with no serious events, discontinuations, or ALT/AST elevations. Ascletis said efficacy was comparable to published secukinumab data, though not from a head-to-head study.