Approval of New Agents after Phase II Trials.

Cancer drug approval has evolved as the understanding of cancer biology, and the ability to select patients for trials of targeted agents, has matured. The longstanding reliance on Phase III trials to prove drug efficacy and positive impact on patient survival may no longer be necessary, as early trials, particularly the expansion phase of a Phase I trial, may provide convincing evidence of a high response rate to a targeted drug in a patient population who has been poorly responsive to conventional therapy. If the new drug produces no safety signals of great concern, and if a validated biomarker for patient selection has been established and is readily available, accelerated approval may be achievable prior to completion of a randomized trial. The advantages, and potential downside, of rapid approval scenarios will be discussed in this article.