Aclaris Therapeutics Says Will Discontinue Further Development Of ATI-450 Program

(RTTNews) - Biopharmaceutical company Aclaris Therapeutics, Inc. (ACRS) announced Monday top-line results from a Phase 2b study of zunsemetinib (ATI-450), an investigational oral MK2 inhibitor, in subjects with moderate to severe rheumatoid arthritis.

ATI-450-RA-202 is a Phase 2b, randomized, multicenter, double-blind, placebo-controlled, dose-ranging study to investigate the efficacy, safety, tolerability, pharmacokinetics and pharmacodynamics of two doses of zunsemetinib plus methotrexate (MTX) versus placebo plus MTX in patients with moderate to severe RA who have had an inadequate response to MTX alone.

The study enrolled 251 patients across three treatment arms (ATI-450 20mg BID, ATI-450 50mg BID, Placebo BID) at approximately 40 trial sites in the United States, Poland, Bulgaria and Czech Republic.

The primary efficacy endpoint is the proportion of patients achieving an ACR20 response following 12 weeks of treatment. Secondary efficacy endpoints included ACR50 response, ACR70 response, DAS28-CRP and other pertinent RA measures.

In the trial, patients administered either the 20mg or 50mg dose did not meet the primary endpoint of ACR20 response or any of the secondary efficacy endpoints at 12 weeks, including ACR50 response, ACR70 response, and DAS28-CRP.

There was no notable differentiation between zunsemetinib and placebo across any measures of efficacy at week 12. No meaningful safety findings were observed.

Based on the overall program results, Aclaris said it will discontinue further development of the ATI-450 program, including halting enrollment of Aclaris' ongoing Phase 2a trial of zunsemetinib in psoriatic arthritis.