Progression-Free Survival as a Clinical Trial Endpoint in Advanced Renal Cell Carcinoma

Traditionally, overall survival (os) has been considered the “gold standard” for evaluating new systemic oncologic therapies, because death is easy to define, is easily compared across disease sites, and is not subject to investigator bias. However, as the available options for continuing therapy increase, the use of os as a clinical trial endpoint has become problematic because of the increasing crossover and contamination of trials. As a result, the approval of promising new therapies may be delayed. Many clinicians believe that progression-free survival (pfs) is a more viable option for evaluating new therapies in metastatic and advanced renal cell carcinoma. As with all endpoints, pfs has inherent biases, and those biases must be addressed to ensure that trial results are not compromised and that they will be accepted by regulatory authorities. In this paper, we examine the issues surrounding the use of pfs as a clinical trial endpoint, and we suggest solutions to ensure that data integrity is maintained.