Expression of AR-V7 in Circulating Tumour Cells Does Not Preclude Response to Next Generation Androgen Deprivation Therapy in Patients with Castration Resistant Prostate Cancer

The androgen receptor splice variant AR-V7 has recently been discussed as a predictive biomarker for nonresponse to next-generation androgen deprivation therapy (ADT) in patients with castration-resistant prostate cancer. However, we recently identified one patient showing a response from abiraterone despite expression of AR-V7 in his circulating tumour cells (CTC). Therefore, we precisely assessed the response in a cohort of 21 AR-V7 positive castration-resistant prostate cancer patients who had received therapy with abiraterone or enzalutamide. We detected a subgroup of six AR-V7 positive patients showing benefit from either abiraterone or enzalutamide. Their progression free survival was 26 d (censored) to 188 d. Four patients displayed a prostate-specific antigen decrease of >50%. When analysing prior therapies, we noticed that only one of the six patients had received next-generation ADT prior to CTC collection. As a result, we conclude that AR-V7 status in CTC cannot entirely predict nonresponse to next generation ADT and AR-V7-positive patients should not be systematically denied abiraterone or enzalutamide treatment, especially as effective alternative treatment options are still limited.

A subgroup of patients can benefit from abiraterone and/or enzalutamide despite detection of AR-V7 splice variants in their circulating tumour cells.

European urology. 2016 Jul 25 [Epub ahead of print]

Christof Bernemann, Thomas J Schnoeller, Manuel Luedeke, Konrad Steinestel, Martin Boegemann, Andres J Schrader, Julie Steinestel

Clinic of Urology, University Hospital Muenster, Muenster, Germany., Clinic of Urology, University Hospital Ulm, Ulm, Germany., Clinic of Urology, University Hospital Ulm, Ulm, Germany., Gerhard-Domagk-Institute of Pathology, University Hospital Muenster, Muenster, Germany., Clinic of Urology, University Hospital Muenster, Muenster, Germany., Clinic of Urology, University Hospital Muenster, Muenster, Germany., Clinic of Urology, University Hospital Muenster, Muenster, Germany. Electronic address: .

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