Efficacy litmus test

When small Phase II trials aren't powered to show efficacy, questions always remain as to whether to go into Phase III studies. Icos Corp. believes that the Phase II safety profile of its LeukArrest monoclonal antibody to treat acute ischemic stroke justified the start of an 800-patient Phase III trial last week. The company said an interim analysis of the Phase III data will serve as the efficacy litmus test.

"You scale clinical trials to accomplish different goals," said Thomas St. John, vice president of therapeutic development. "The Phase II trial had a good safety profile with a suggestion of efficacy. For us, this validated exposing 800 patients to LeukArrest in the Phase III study of full efficacy."...