Testing for AR-V7 “validated” in men with CRPC

According to an article yesterday on Cancer Therapy Advisor, testing for circulating tumor cell (CTC)-based androgen receptor splice variant-7 (AR-V7) has now been validated as a prognostic test for men with castration-resistant prostate cancer (CRPC) receiving hormone therapy.

This statement in Cancer Therapy Advisor is based on data reported by Silberstein et al. at the Genitourinary Cancers Symposium back in February this year.

As far as we are aware, this test (which can be carried out on a simple blood sample) is still only available, as yet, through the Molecular Diagnostics Laboratory at Johns Hopkins Medical Center in Baltimore, MD.

Many might argue that the use of this test had actually been “validated” at least a couple of years ago, when the US Food and Drug Administration approved a clinical trial initiated by Tokai Pharmaceuticals. The trial was designed to test an investigational drug for the treatment of men with advanced prostate cancer who were AR-V7 positive. The test developed at Johns Hopkins was used to clearly identify men who could be entered into that trial (although, unfortunately, that trial showed that the investigational drug was not effective in the treatment of AR-V7 positive patients).

4 Responses

  1. I heard from the Genomic Health CMO late last year that they are planning to offer an AR V7 test by this summer.

  2. So other than knowing that your life expectancy is lower if you are CTC-positive and AR-V7 positive, is the test of any value?

  3. Dear Anonymous:

    There are a number of companies trying to develop new drugs (or re-evaluate older drugs) to see if they have benefit specifically in the treatment of men with the AR-V7 gene mutation. So for those men who are interested in participating in such trials, yes, the test has value. As a test for its own sake today, no it probably doesn’t.

  4. There is a financial and a time value from AR-V7 testing. If you are AR-V7 positive, then you may decide with your medical team to skip a second-line antiandrogen like Zytiga or Xtandi.

    Financially, 1 month’s supply, even with insurance, can be pricey … as much as $2,500 to $3,000 with insurance depending on coverage; $8,000 to $10,000 without.

    Timewise it can be more efficient, since you can move to another treatment sooner.

    One other point, the AR-V7 test does not work with a low tumor burden. There are not enough “snips” (fragmented tumor cells) in the blood stream to register.

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