Positive top-line data for SerpinPC in severe hemophilia A and B

Shares of Centessa Pharmaceuticals (Nasdaq: CNTA) were up 17.6% at $24.76 in early trading today after, together with subsidiary ApcinteX, it announced positive top-line results from the Phase IIa part of AP-0101, the six-month repeat dose portion of its ongoing first-in-human proof-of-concept study evaluating SerpinPC in severe hemophilia A and B patients.

AP-0101 is a Phase I/IIa proof-of-concept study evaluating SerpinPC, an inhibitor of activated protein C (APC), in 23 male subjects with either severe hemophilia A or B who were not on prophylaxis. The Phase IIa part of the study assessed the safety, tolerability and pharmacokinetics across three dose cohorts (0.3mg/kg, 0.6mg/kg and 1.2mg/kg) of SerpinPC administered as a subcutaneous (SC) injection every four weeks over a 24-week period (six total doses). Reduction in the annualized bleeding rates (ABRs) were exploratory outcomes. Although eligible, none of the patients in the study had inhibitors.

SerpinPC was well-tolerated. As previously disclosed, one subject with a history of a skin disorder discontinued treatment on SerpinPC due to an injection site reaction. No other SerpinPC-related adverse events have been recorded. There was no reported sustained elevation in D-dimer, a sensitive measure of excess thrombin generation, throughout the 24-week study. Two subjects had anti-drug antibodies and remained on treatment without apparent impact on ABRs.