Ascletis ASC50 achieved a 48.9% placebo-adjusted PASI reduction in mild-to-moderate plaque psoriasis, with a 6.5-day half-life supporting weekly dosing studies.
Written By: Kirti Kumbhar, M. Pharm (QA)
Reviewed By: Pharmacally Editorial Team
Ascletis Pharma reported positive proof-of-concept results for ASC50, an oral small-molecule interleukin-17A (IL-17A) inhibitor, in patients with mild-to-moderate plaque psoriasis. Once-daily 200 mg dosing for 28 days produced a 48.9% placebo-adjusted reduction in psoriasis area and severity index (PASI) score, while a 6.5-day steady-state elimination half-life supported further evaluation of less frequent oral dosing.
ASC50 Shows Sustained PASI Reduction After Treatment
Ascletis evaluated ASC50 in a randomized, double-blind, placebo-controlled Phase I study (NCT07024602) in U.S. patients with mild-to-moderate plaque psoriasis. The trial assessed the safety, efficacy, and pharmacokinetics of once-daily 200 mg ASC50 over 28 days.
At the end of the treatment period, ASC50 produced a 48.9% placebo-adjusted reduction in PASI score.
The greatest observed placebo-adjusted PASI reduction occurred after dosing had stopped. The reduction reached 60.7% six days after the final dose and 65.9% 15 days after the final dose. These post-treatment findings, together with ASC50’s pharmacokinetic profile, provide additional support for evaluating once-weekly oral dosing in subsequent studies.
The study enrolled patients with mild-to-moderate plaque psoriasis, a population in which treatment decisions can differ from those for moderate-to-severe disease. If ASC50 demonstrates sustained efficacy and an acceptable safety profile in later-stage studies, its oral route could provide an additional treatment option across a broader range of disease severity.
Oral Small-Molecule IL-17A Inhibition
ASC50 is an orally administered small-molecule inhibitor of IL-17A, a validated therapeutic target in psoriasis and other immune-mediated inflammatory diseases.
Unlike marketed IL-17A antibody therapies, ASC50 is being developed as a small molecule intended for oral administration. The compound is a new chemical entity with a novel scaffold.
Elevated plasma IL-17A concentrations after 28 days of treatment were consistent with strong target engagement, providing pharmacodynamic evidence that ASC50 was engaging its intended pathway.
6.5-Day Half-Life Supports Evaluation of Weekly Dosing
Pharmacokinetic analysis showed a steady-state elimination half-life of 6.5 days following 28 days of treatment. This relatively long half-life provides a pharmacological basis for evaluating less frequent administration, including once-weekly oral dosing.
The persistence of the PASI response after treatment cessation also supports this development strategy. However, the current findings do not establish the efficacy of once-weekly dosing. That regimen will require direct evaluation in appropriately designed clinical studies.
Ascletis reported that the PASI reduction observed with 200 mg once daily was comparable with published data for secukinumab, an approved IL-17A antibody. The comparison was not head-to-head and therefore cannot establish comparative efficacy.
Favorable Short-Term Safety Profile
ASC50 was well tolerated during the 28-day treatment period. All reported adverse events were Grade 1 and transient, with no serious adverse events or treatment discontinuations.
No elevations in alanine aminotransferase (ALT) or aspartate aminotransferase (AST) were observed, and the company reported no hepatic safety signal during the study.
The safety findings remain preliminary because the study involved short treatment and limited patient exposure. Larger and longer-duration studies will be needed to better characterize ASC50’s safety profile.
Further Clinical Development
Jinzi Jason Wu, Ph.D., founder, chairman and CEO of Ascletis, said the efficacy, safety, and pharmacokinetic findings support further development of ASC50 as an oral IL-17A inhibitor, including investigation of once-weekly administration.
The company has not disclosed detailed plans for the next clinical stage in the supplied announcement. Future studies will need to confirm the efficacy signal over longer treatment periods, assess safety in a larger patient population, and directly evaluate whether ASC50 can maintain clinical activity with once-weekly dosing.
Reference
Ascletis Announces Positive Results from 28-Day Proof-of-Concept Clinical Study in U.S. for ASC50, a First-in-Class and Best-in-Class Oral Small Molecule IL-17A Inhibitor for the Treatment of Plaque Psoriasis, Asceltis, 29 September 2026
A Study to Evaluate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics and Efficacy of ASC50 Tables in Healthy Participants and Participants with Plaque Psoriasis, ClinicalTrials.gov ID NCT07024602
About the Writer
Kirti Kumbhar (LinkedIn) is an M.Pharm graduate with experience in Quality Assurance at Lupin Limited and a strong interest in clinical research, regulatory affairs, and Trial Master File (TMF) management. She has developed knowledge of regulatory documentation, quality systems, compliance, and healthcare research through her professional experience. Passionate about clinical development and continuous learning, Kirti is committed to supporting high-quality healthcare documentation, regulatory excellence, and research-driven healthcare advancements.