Reasons for Clinical Failures by Phase

Published on: 

Applied Clinical Trials

Applied Clinical Trials, Applied Clinical Trials-12-01-2013, Volume 22, Issue 12


The Tufts Center for the Study of Drug Development (Tufts CSDD) recently analyzed the reasons for clinical failures for 410 drugs that entered human testing between 2000 and 2009.


The results of this analysis show that commercial viability—as opposed to safety—is the leading cause of Phase I failures. Commercial viability played a diminishing role in the reasons for drugs failing in later clinical phases. Safety issues accounted for one-third of all drugs that failed in Phase I and Phase III studies; and for 17% of all Phase II failures.

Efficacy issues dominated both Phase II and III accounting for more than half of the total drugs that failed (54% and 52% respectively). Tufts CSDD researchers conclude that the ever-changing commercial landscape combined with insights gleaned from later-stage studies conducted among larger patient populations present ongoing drug development risk-dynamics that are difficult for sponsors to anticipate and manage.

—Tufts Center for the Study of Drug Development,