20 April 2016 - The effectiveness of cancer drugs is demonstrated by prolonging survival and/or improving patient symptoms and quality of life. Overall survival (OS), defined as the time from random assignment to the date of death from any cause, is objective, precise, and easy to measure and interpret, and hence has been considered the most reliable and clinically meaningful end point for evaluating drug efficacy in oncology clinical trials.

This endpoint, however, requires a large sample size and prolonged follow-up, which not only make such trials expensive, but also create the risk of the drug under investigation becoming obsolete by the time the trial is complete. In addition, OS is potentially confounded or diminished by effective postprogression therapies (including cross-over).

These limitations of the OS endpoint are the primary motivations for the use of surrogate end points in oncology clinical trials, which are particularly important for rare diseases and diseases with effective subsequent-line therapy, especially in this era of personalized medicine.

For more details, go to: http://jco.ascopubs.org/content/34/13/1436?cmpid=jco_etoc_1May2016