Dr. Scher on the Future of the Circulating Tumor Cell Test

Howard I. Scher, MD, chief of the Genitourinary Oncology Service at the Sidney Kimmel Center for Urologic and Prostate Cancers at Memorial Sloan-Kettering, lead author of the COU-AA-301 trial that investigated circulating tumor cells (CTC), elaborates on the future of the CTC blood test.

Dr. Scher says the CTC blood test has a clearance as an aid to monitoring patients with breast cancer, colorectal cancer, and prostate cancer. Dr. Scher and colleagues wanted to take the test one step further and see if they could develop a biomarker panel that could be used in clinical trials in order to predict early that a drug will prolong life. That requires a test that is analytically validated and also requires a series of clinical trials no different than what's done with drugs of an exploratory phase, phase I, phase II, and phase III. In this case, it requires multiple phase III trials which will show consistent results that the biomarker that is developed is predictive of survival. When that goal is accomplished, they can then apply to the FDA for a formal qualification, which will allow that endpoint to be used in trials in place of survival.