Ascletis Pharma Inc. (Ascletis) released a voluntary announcement on 29 September 2026 detailing positive topline results from its randomized, double-blind, placebo-controlled 28-day Phase I proof-of-concept trial (NCT07024602) in the United States evaluating ASC50, an in-house-developed, oral small-molecule interleukin-17A (IL-17A) inhibitor, in patients with mild-to-moderate plaque psoriasis.

Key Efficacy Highlights • A 48.90% placebo-adjusted reduction in Psoriasis Area and Severity Index (PASI) was observed after once-daily 200 mg dosing for 28 days. • Post-treatment follow-up showed further PASI improvements, with placebo-adjusted reductions of 60.70% at Day 34 (six days after the final dose) and 65.90% at Day 43 (15 days after the final dose), supporting potential once-weekly oral dosing. • The magnitude of PASI reduction at 200 mg once daily was reported as comparable to published data for the marketed injectable IL-17A antibody secukinumab (non-head-to-head comparison).

Pharmacokinetics and Target Engagement • Patients achieved a steady-state elimination half-life of 6.5 days following 28 days of dosing, a duration consistent with once-weekly oral administration. • Elevated plasma IL-17A levels confirmed strong target engagement after treatment.

Safety Profile • All adverse events were mild (Grade 1) and transient; no serious adverse events or study discontinuations occurred. • No elevations in alanine aminotransferase (ALT) or aspartate aminotransferase (AST) were detected, and no hepatic safety signals were observed.

Strategic Context ASC50 is a new chemical entity with a novel scaffold targeting IL-17A, a validated pathway implicated in multiple autoimmune and inflammatory diseases. Positive safety, efficacy, and pharmacokinetic outcomes position ASC50 as a potential first-in-class and best-in-class oral alternative to existing injectable biologic therapies for plaque psoriasis.

Regulatory Note Ascletis cautions that successful development, manufacturing, and commercialization of ASC50 are not guaranteed, in accordance with Rule 18A.05 of the Hong Kong Stock Exchange Listing Rules.