AR-V7 and Resistance to AR Targeting Agents (Xtandi/Zytiga)

Looking for opinions concerning something my NIH trial doctor said when I asked if they would collaborate with Hopkins and test my circulating tumor cells for the AR-V7 variant (which they are looking into).

His concern with testing for the AR-V7 variant in my my cancer cells now, is that it may not represent the cancer that remains at the end of my current protocol. My words; but lets say Xtandi did not work for me because I do carry the AR-V7 variant now, but what if the chemo/XL-184 kills off all the AR-V7 cells; could the remaining cells now be sensitive to Zytiga?

Is the best time to test for these kind of cancer markers only valuable just prior to starting a new therapy?

Also, when they discuss cross resistance of these two drugs, could it really the fact that the first one tried had no success at killing off the AR-V7 cells, so when the next one is tried, it will not be successful either?

A recent video from the Hopkins doc click here

I agree Allen.

When the doc suggested that, it made sense to me also. However, the curious side of me wanted to know if AR-V7 was the reason for my resistance, and maybe the data would further support Dr. Antonarakis findings. If it's for science (and not too costly), I would want to do it now, and then again at the end of the protocol. I may however be too far into the current trial for such testing to be very definitive.

I guess this would all suggest that just because a specific therapy, like Xtandi, may have “failed” at one point in the fight, it is possible that it could be of use sometime later in the fight (assuming you have some marker like an AR-V7 marker to test for).

Allen - does the CTC automatically test for the AR-V7 variant. I understand an issue with the CTC is false positives and false negatives.

I have had two CTC's a while back, and each showed no tumors in course of forming. I also seem to be responding to Zytiga though my PSA was quite low even before Zytiga.

So just wondering if the AR-V7 variant if tested for would have confirmed that Zytiga might work for me.

See you Monday night at your LA support group meeting. If you can be there a little early, you can walk me through my detailed dosage plan Dr. King provided at my reqest, or even better I can buy you supper somewhere nearby if you are available even earlier. Will also be back in LA Oct 16-17.

My SBRT #3 is at 1:45 and I have from then til your meeting starts at 6 PM open.

LupronJim

No Prob, and I will see you around 6 PM Allen.

For a change I will not be rushing in or out of LA Monday.

LupronJim

Hi Dan-

My Current Events discussion group is at a Senior Center on Fairfax.

The PC Support Group is in Santa Monica at the Cancer Support Community Benjamin Center on Bundy and LaGrange. They meet the second Monday of every month from 6-8PM. Come any time.

- Allen