Blood Based Biomarker May Guide Therapy For Advanced Prostate Cancer

Emmanuel S. Antonarakis, M.B.B.CH   Department of Urology and Oncology Johns Hopkins University School of Medicine Baltimore, MarylandMedicalResearch.com Interview with:
Emmanuel S. Antonarakis, M.B.B.CH
Department of Urology and Oncology
Johns Hopkins University School of Medicine
Baltimore, Maryland

Medical Research: What is the background for this study? What are the main findings?

Dr. Antonarakis: In a previous publication, we reported that detection of the androgen receptor splice variant 7 (AR-V7; an abnormal version of the androgen receptor) in circulating tumor cells from patients with advanced prostate cancer was associated with resistance to hormonal therapies such as abiraterone and enzalutamide. Here, we aimed to explore the role of AR-V7 in the context of chemotherapy treatment. We showed that detection of AR-V7 was not associated with resistance to the chemotherapy drugs docetaxel or cabazitaxel, and that AR-V7-positive patients could still derive benefit from these chemotherapies.

Medical Research: What should clinicians and patients take away from your report?

Dr. Antonarakis: In patients who have AR-V7-positive circulating tumor cells, chemotherapy (with docetaxel or cabazitaxel) might be more effective than hormonal therapy (with abiraterone or enzalutamide). However, in patients who have AR-V7-negative circulating tumor cells, hormonal therapies and chemotherapies may work equally well while the former has less toxic side effects. Therefore, blood-based testing for AR-V7 might prove useful in helping to guide patients in terms of selecting the optimal treatment for their advanced prostate cancer.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Antonarakis: Our findings certainly require confirmation in larger prospective studies, and such studies are already ongoing. For example, in one study we will prospectively assess the clinical utility of three blood-based AR-V7 tests in 120 patients with advanced prostate cancer who are about to begin treatment with abiraterone or enzalutamide. In another randomized phase-2 study, men will be randomized to receive either abiraterone/enzalutamide or cabazitaxel, and will be prospectively tested for AR-V7 before trial entry and also at the time of progression. Such studies will be able to determine the broader clinical significance of the AR-V7 biomarker test in a multi-center fashion.

Citation:

Antonarakis ES, Lu C, Luber B, et al. Androgen Receptor Splice Variant 7 and Efficacy of Taxane Chemotherapy in Patients With Metastatic Castration-Resistant Prostate Cancer. JAMA Oncol. Published online June 04, 2015. doi:10.1001/jamaoncol.2015.1341.

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MedicalResearch.com Interview with: Emmanuel S. Antonarakis, M.B.B.CH, Department of Urology and Oncology, Johns Hopkins University School of Medicine, & Baltimore, Maryland (2015). Blood Based Biomarker May Guide Therapy For Advanced Prostate Cancer