Dyax Corp. (NASDAQ: DYAX) announced today the decision to discontinue the Company’s Phase 2 trial investigating ecallantide in the acute treatment of angiotensin converting enzyme (ACE) inhibitor-induced angioedema based upon the results of an interim analysis. This double-blind, placebo-controlled, randomized, dose-ranging study was designed to evaluate the efficacy and safety of ecallantide (10, 30, or 60 mg subcutaneous doses) compared to placebo, with a goal of enrolling 176 patients. The primary endpoint was the proportion of patients meeting a set of criteria indicating eligibility for discharge from the emergency department within 6 hours following study drug administration.
Safety was not a factor in the Company’s decision to stop the clinical trial. Separately from this interim analysis of the efficacy data, an independent Data Safety Monitoring Board (DSMB) met on May 15, 2012, and reviewed blinded safety data for the first 25% of patients enrolled in the trial. The DSMB did not identify any safety concerns and did not recommend any changes to the conduct of the study.
Prior studies and literature suggested that ACE inhibitor-induced angioedema is complicated by high rates of morbidity, which drove the assumptions used to power the study. This large, multi-center, placebo-controlled trial provided an opportunity to better understand the disease, and, as such, Dyax determined that it would be prudent to conduct an interim analysis of efficacy data.
Data from the first 72 patients treated in the trial suggests a trend favoring a treatment with ecallantide over placebo; however, this trend is not statistically significant. Because the observed response rate to placebo was substantially higher than originally anticipated, the study was determined to be inadequately powered to detect a statistically significant difference between ecallantide and placebo. In addition, based upon the primary endpoint data, the enrolled population does not appear to reproduce the high morbidity described in previous medical literature.