Toinv,

Yes, it is fair to call Constellation and its CPI-1205 EZH2 inhibitor a competitor from the perspective of epigenetic drugs for treating mCRPC. There are several other classes of epigenetic drugs beyond BET inhibitors and EZH2 inhibitors (see here for a great review). So the list of Zenith competitors in the sense of any epigenetic drug is not limited to just companies with BET and EZH2 inhibitors. 

Constellation also has a pan BET inhibitor CPI-0610, which was one of the first BET inhibitors in clinical trials. I don't know if CPI-0610 has been tested in prostate cancer. There is quite a long list of other companies with clinical stage BET inhibitors, including some in Phase 2 and/or being tested in prostate cancer (i.e. Gilead's GS-5829). I previously compiled a list of BET inhibitors in clinical trials. It is outdated but still includes the most advanced BET inhibitor programs. Additionally, I stumbled upon this webpage that has a very good list of 25 clinical and pre-clinical BET inhibitors. It had several that weren't on my prior list, some of which are only pre-clinical. Zenith is not alone in the pan BET inhibitor oncology space. But the safety profile and efficacy of ZEN-3694 puts them out in front of the field in my opinion.

BearDownAZ