The disparity between objective and subjective clinical end points was highlighted last week by the failure of a Phase III trial of Veletri tezosentan, Actelion Ltd.'s endothelin receptor antagonist to treat acute heart failure. Unlike a previous Phase III trial that had demonstrated efficacy on objective measures of hemodynamics (blood flow), the RITZ-1 trial failed to show improvements in dyspnea (shortness of breath) when hemodynamics were not measured.

ATLN, partner Genentech Inc. and the FDA designed the trials to assess the end points separately to avoid the possibility that one might confound the other. The results could shed light on how best to assess a complex treatment population. The price, however, is at best an 18-month delay in an NDA filing.