tada - I'm not sure but I think you might be correct on the FDA letter. Also, RVX properly released the information in a news release, they didn't just informally tell us. That would be risky if it were not true. Also, DM has recently stated that the BTD, "is firmly in place".

https://www.globenewswire.com/en/news-release/2020/02/03/1978651/0/en/Resverlogix-Receives-US-FDA-Breakthrough-Therapy-Designation-for-Apabetalone.html