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receptor splice variant 7 or 9 in whole blood does not predict response to androgen-axis–targeting agents in metastatic castration-resistant prostate cancer. Eur. Urol. https://doi.org/ 10.1016/j.eururo.2018.01.007 (2018) FURTHER READING Attard, G. & Antonarakis, E. S. Prostate cancer: AR aberrations and resistance to abiraterone or enzalutamide. Nat. Rev. Urol. 13, 697–698 (2016) Expression of AR-V7 or AR-V9 was not associated with a PSA response A new report in European Urology shows that expression of androgen receptor variants 7 and 9 (AR-V7 and AR-V9) measured in whole blood is not predictive of treatment outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC). “AR-Vs are truncated isoforms of the AR that retain constitutive activity and are purported to be associated with resistance to novel hormonal therapies (abiraterone and enzalutamide),” explains Arun Azad, senior author of the study. “However, data from the ARMOR-3 trial called this belief into question; hence, we felt it was critical to assess AR-V7 and AR-V9 expression in patients with mCRPC to determine the predictive utility of these AR variants.” The team collected whole-blood samples from 37 patients with mCRPC before these men started abiraterone or enzalutamide treatment and determined AR-V RNA levels using reverse transcription (RT)-PCR assays with primers specific for AR-V7 and AR-V9. Clinical outcome data were collected at a median follow-up time of 7.3 months. Overall, 24% of men were AR-V+ (seven were AR-V7+ and two were AR-V9+). Expression of AR-V7 or AR-V9 was not associated with a PSA response (50% decrease at 3 weeks) or PSA-progression-free survival (PFS). Analysing AR-V7 positivity, 57% of AR-V7+ men and 66% of AR-V7men had a PSA response (P = 0.6). P R O S TAT E C A N C E R