Dr. Armstrong on the Utility of AR-V7 as a Biomarker in Prostate Cancer

Andrew J. Armstrong, MD, professor of medicine, associate professor in pharmacology and cancer biology, and professor in surgery at Duke University School of Medicine, and member of the Duke Cancer Institute, discusses the utility of AR-V7 as a biomarker in prostate cancer.

In the laboratory, some initial data suggested that AR-V7 could make a cancer resistant to taxane chemotherapy; however, in the clinic, that was not consistently observed, says Armstrong. Patients with AR-V7 detection were responding to and had very similar benefits with taxane chemotherapy as men without AR-V7 detection, explains Armstrong.

All previous data were based on single-institution experiences and were largely retrospective. The PROPHECY trial provided the first prospective validation of AR-V7 as a negative biomarker of response to abiraterone acetate (Zytiga) and enzalutamide (Xtandi). AR-V7 is not commonly detected; only about 10% to 20% of patients with prostate cancer harbor it in their circulating tumor cells. As such, the majority of patients will test negative for AR-V7. Investigators continue to search for additional therapeutic biomarkers in this patient population, concludes Armstrong.