AR-V7 as a Predictive Biomarker in Metastatic CRPC

Transcript: Judd Moul, MD: Let’s move on to a couple of other updates in metastatic CRPC [castration-resistant prostate cancer]. First are biomarkers. I want to get the panelists’ opinions about how you use the AR-V7 [androgen receptor splice variant 7] assay, which, to my knowledge, is the only officially FDA-approved serum or blood biomarker that’s available. Neeraj, let’s start with you this time.

Neeraj Agarwal, MD: I was hoping you would not ask me to start with this one, because in reality, I think what happened with the AR-V7 story was a very nice step in the right direction. Somebody worked to establish a biomarker, and I would like to applaud the whole group at the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University for pursuing this project and publishing in the New England Journal of Medicine.

Having said that, it has not really impacted the clinical game, in my opinion. By the time you get the results of the AR-V7, you already know whether patients are responding to enzalutamide. Really, all I can say in summary is that it has not impacted my practice, and I’m not using the AR-V7 biomarker because it is not really changing anything about what I’m doing, anyway.

Judd Moul, MD: Alicia?

Alicia Morgans, MD, MPH: I would have to say the same thing. It’s a matter of recognizing that for the most part, patients don’t respond to the second AR [androgen receptor]—directed therapy after the first has failed them. I typically move on to a treatment with a different mechanism of action at that point, rather than the AR-V7 assay. Some people are using it, so I don’t want to say that no one does, but it has not become commonplace in my practice.

Judd Moul, MD: Tanya?

Tanya Dorff, MD: If I’m going to spend the money, I would much rather get genomic profiling, because I think there’s a lot more that I’m going to do with that information. If I come across 1 of those rare but very happy patients who is MSI [microsatellite instability] high, like a satellite instability, where pembrolizumab is approved in that setting across histologies, or if you have that genomic marker. I think that adds value. Finding a DNA-repair mutation adds value. When I think of a genomic test, AR-V7 could impact whether you would choose a taxane versus switching from NSAID [nonsteroidal anti-inflammatory drug] to ABI [abiraterone], or ABI [abiraterone] to NSAID, but there’s so much more out there.

Judd Moul, MD: We talked earlier about nonmetastatic CRPC. There is essentially no role for AR-V7 prior to initiating therapy for M0 CRPC. By the same token, a guy showing up with newly diagnosed metastatic or M1 hormone-sensitive prostate cancer for the first time, there is no role for AR-V7 prior to starting treatment. Once you get to progressive metastatic CRPC, that’s where it’s FDA approved. We’ll leave it at controversial, and at least from the 3 panelists we have here today. It does not necessarily have a clear role that they see in their practices. At the AUA [American Urological Association annual meeting] last month, I was part of a panel with Chris Sweeney, MBBS, and to be honest with you, I was surprised. I think much of the urologic audience was surprised that he had the same opinion. It was almost like a gasp from the urologists, because we assumed that medical oncologists love biomarkers. You mentioned more data, right? I think a lot of the urologists were surprised that the medical oncology community had not really been embracing the AR-V7.

Transcript Edited for Clarity