Breast Cancer Update for Surgeons, Issue 1, 2017 (Video Program)Targeting the androgen receptor in patients with triple-negative BC
3:02 minutes.
TRANSCRIPTION:
DR GRADISHAR: The idea of using antiandrogen therapy is really predicated on the fact that a not insignificant fraction of breast cancers actually express the androgen receptor and probably far more than we initially thought. And part of it, of course, is based on which assay is used. And where the largest interest lies is in so-called triple-negative breast cancer that is AR-positive. And again, it gets back to molecular subtyping of breast cancer. And within the triple-negative group, you can further refine the subdivisions into, depending on whose divisions you use, the Vanderbilt grouping of about 7 different types, an androgen receptor-positive subtype falls out. So the early data with bicalutamide, drugs that we typically think of more in relation to prostate cancer, found that they had to screen like 500 patients to find 50. And there was some clinical evidence of benefit from utilizing monotherapy with bicalutamide in that patient population. And then more recently, enzalutamide, another prostate cancer-like drug, has also been evaluated. The interesting thing in that experience — and we participated in those trials — is that rather than 10%, the fraction of patients who had AR expression was much higher. So the assay used was somewhat proprietary. But we have some further evidence that this is not so uncommon as we thought. And the data with enzalutamide has also shown clinical activity that probably is not so different than some chemotherapy drugs in the same population. I think for a slice of the pie in terms of specific kinds of breast cancer, these kinds of strategies might be useful. And there are even adjuvant trials that are exploring integrating these kinds of agents into AR-positive, triple-negative breast cancer. DR LOVE: Adjuvant trials? DR GRADISHAR: Pilot trials. DR LOVE: Wow! That's interesting. Any innovative adjuvant trials going on right now? DR GRADISHAR: I would say the triple-negative disease setting is one where, because of the data with platinums — although it’s a little bit discordant — in the preop setting, where platinums may or may not help in terms of increasing the pCR rate, there is a large trial in the adjuvant setting asking that question in triple-negative breast cancer, ACT versus ACT with platinum. So that’ll get at the issue of whether there is an added advantage in terms of reducing the risk of recurrence with platinum. |