Scher HI, et al. - Researchers determined the efficacy of a validated assay for the nuclear-localized androgen receptor splice variant 7 (AR-V7) protein in circulating tumor cells in determining differential overall survival among patients with metastatic castration-resistant prostate cancer (mCRPC) treated with taxanes vs androgen receptor signaling (ARS) inhibitors. Outcomes suggest the utility of the validated nuclear-localized AR-V7 assay in selecting a taxane or ARS inhibitor and providing individual patient benefit.

Methods

• From December 31, 2012, to September 1, 2016, researchers conducted a blinded correlative study including 142 patients with histologically confirmed mCRPC and who were treated at Memorial Sloan Kettering Cancer Center, The Royal Marsden, or the London Health Sciences Centre.
• They obtained blood samples prior to administration of ARS inhibitors or taxanes as a second-line or greater systemic therapy for progressing mCRPC.
• Main outcomes and measures assessed were overall survival after treatment with an ARS inhibitor or taxane in relation to pretherapy AR-V7 status.

Results

• Researchers included 142 patients (mean [SD] age, 69.5 [9.6] years), of these, 70 were designated as high risk by conventional prognostic factors.
• In this high-risk group, superior overall survival were noted among patients positive for AR-V7 who were treated with taxanes vs those treated with ARS inhibitors (median overall survival, 14.3 vs 7.3 months; hazard ratio, 0.62; 95% CI, 0.28-1.39; P=.25).
• Superior overall survival was evident for patients negative for AR-V7 who were treated with ARS inhibitors vs those treated with taxanes (median overall survival, 19.8 vs 12.8 months; hazard ratio, 1.67; 95% CI, 1.00-2.81; P=.05).