Aclaris Therapeutics (ACRS), a clinical-stage biopharmaceutical company focused on developing novel drug candidates for immuno-inflammatory diseases, today announced positive preliminary topline results from a 12-week, Phase 2a, multicenter, randomized, investigator and patient-blind, sponsor-unblinded, parallel group, placebo-controlled clinical trial to investigate the safety, tolerability, pharmacokinetics and pharmacodynamics of ATI-450, an investigational oral MK2 inhibitor, in subjects with moderate to severe rheumatoid arthritis (RA) (ATI-450-RA-201). ATI-450 was developed internally utilizing Aclaris’ proprietary KINect™ drug discovery platform.
19 subjects were randomized in a 3:1 ratio and received either ATI-450 at 50 mg twice daily or placebo, in combination with methotrexate, for 12 weeks. The primary endpoint was safety and tolerability. Key secondary and exploratory endpoints included the disease activity scores, DAS28-CRP and ACR20/50/70, and the change from baseline in high sensitivity C-reactive protein (hsCRP) and relevant endogenous cytokine levels. As this trial was designed to generate proof of concept, it was not powered to detect statistically significant outcomes on efficacy endpoints.
The mean DAS28-CRP score at baseline was 5.71 for the 16 subjects in the treatment arm and 5.77 for the three subjects in the placebo arm. Seventeen subjects (15 in the treatment arm and two in the placebo arm) completed 12 weeks of treatment.
ATI-450 demonstrated durable clinical activity, as defined by a marked and sustained reduction in DAS28-CRP and evaluation of ACR20/50/70 responses over 12 weeks. The mean change from baseline in DAS28-CRP score at week 12 was a 2.0 reduction in the treatment arm compared to a 0.35 increase in the placebo arm.
ATI-450 was also evaluated at higher doses in a separate Phase 1 clinical trial in healthy subjects (ATI-450-PKPD-102). In this placebo-controlled Phase 1 trial, one group of healthy subjects received 80 mg of ATI-450 twice daily and another group of healthy subjects received 120 mg of ATI-450 twice daily over 6.5 days. No dose-limiting toxicity was observed. Ex vivo analysis of blood samples from this Phase 1 trial showed that increased cytokine inhibition was achieved with these higher doses of ATI-450. A final analysis of this trial is underway.