Circulating tumor cell (CTC)-based androgen receptor splice variant 7 (AR-V7) detection may serve as a treatment selection biomarker in men with castration-resistant prostate cancer (CRPC), a new study published online ahead of print in JAMA Oncology has shown.
Previous research has demonstrated the AR-V7 was associated with primary resistance to enzalutamide or abiraterone therapy. For this study, researchers sought to investigate whether AR-V7 status would have an impact on chemotherapy sensitivity.
Researchers enrolled 37 patients with metastatic CRPC initiating treatment with docetaxel or cabazitaxel at The Johns Hopkins Hospital in Baltimore, Maryland. Of those, 17 had detectable AR-V7 in CTCs.
Results showed that PSA responses occurred in both AR-V7-positive and AR-V7-negative patients (P=0.019), and PSA progression-free survival (P=0.32) and progression-free survival (P=0.11) were similar in both AR-V7-positive and AR-V7-negative men.
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The study also demonstrated superior clinical outcomes with taxanes compared with enzalutamide or abiraterone in AR-V7-positive patients, while outcomes in AR-V7-negative men did not differ by treatment type.
In AR-V7-positive men, PSA responses were higher in taxane-treated men (P<0.001), and PSA progression-free survival (P=0.001) and progression-free survival (P=0.003) were significantly longer.
- 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. 2015. [Epub ahead of print]. doi: 10.1001/jamaoncol.2015.1341.