Do you routinely offer AR-v7 testing to determine whether to treat with chemotherapy versus enzalutamide or abiraterone in metastatic castration resistant prostate cancer?

The short answer is no, not yet, and not outside of a research study. AR-V7 testing using a CLIA approved circulating tumor cell (CTC) assay, either Qiagen-Hopkins using the Adnatest RT-PCR platform or the EPIC-Genomic Health protein assay, appear very promising as negative predictors of the clinical benefit of enzalutamide or abiraterone acetate. However, the prevalence of a positive test is <5% in the front line setting making this test not useful in this treatment space. Following progression...

Our perspective is clearly biased, but we are routinely doing AR-V7 testing in the post-Abi or post-Enza patients who have not yet received taxane therapy to help make the choice between second AR-directed agent versus taxane agent versus clinical trial participation. A recent paper by Scher HI et al (JAMA Oncology, epub June 4, 2016) is also supportive of this notion. But this is clearly not the universal standard at present.