The Hub for Disease-Specific Clinical Information
Advertisement
Advertisement

AR-V7 Assays and Treatment Outcomes in Castration-Resistant Prostate Cancer

By: Sara Tewksbury
Posted: Wednesday, May 15, 2019

According to the multicenter PROPHECY study, conducted by Andrew J. Armstrong, MD, of Duke University Medical Center, and colleagues, circulating tumor cell (CTC) androgen receptor splice variant 7 (AR-V7) may be a “strong predictor” of clinical outcomes in men with metastatic castration-resistant prostate cancer who are treated with abiraterone or enzalutamide. These findings, which were published in the Journal of Clinical Oncology, suggest that AR-V7 status may assist in treatment selection beyond prognosis and disease burden.

“Detection of AR-V7 in CTCs by two blood-based assays is independently associated with shorter [progression-free and overall survival] with abiraterone or enzalutamide, and such men with [metastatic castration-resistant prostate cancer] should be offered alternative treatments,” the investigators concluded.

Of the 118 men in the study, 55 were treated with abiraterone, 58 were treated with enzalutamide, and 5 received both therapies concurrently. Baseline CTC AR-V7 levels were detected by two assays—the Johns Hopkins University modified-AdnaTest CTC AR-V7 mRNA assay and the Epic Sciences CTC nuclear-specific AR-V7 protein assay.

At baseline, 28 men tested AR-V7–positive, 88 were AR-V7–negative, and 2 were unevaluable by the Johns Hopkins assay. The Epic protein-based assay found 11 men to be AR-V7–positive, 96 were AR-V7–negative, and 11 were unevaluable.

After the investigators adjusted for CTC number and clinical prognostic factors, they found that detection of AR-V7 by both assays was independently associated with poorer outcomes. Specifically, AR-V7 detection was associated with hazard ratios of 1.9 for progression-free and 4.2 for overall survival with the Johns Hopkins assay. And, the hazard ratios linked to the Epic protein assay were 2.4 for progression-free and 3.5 for overall survival. In addition, fewer confirmed prostate-specific antigen or soft-tissue responses were observed in men with AR-V7–positive disease. The percentage agreement between the two assays was 82%.

Disclosure: The study authors’ disclosure information may be found at ascopubs.org.



By continuing to browse this site you permit us and our partners to place identification cookies on your browser and agree to our use of cookies to identify you for marketing. Read our Privacy Policy to learn more.