biota wins a us patent for treatment of cancer, page-146

According to this paper (p7) you're wrong. There is no involvement of BTA unless the Board of the Patents Appeals and Interferences at USPTO deems an interference, either under it's own steam or as a result of a third party making an application for one.

BTA doesn't formally get involved unless the Board declares an interference might exist.

I suspect they might be making preliminary preparations while the first step of interference is underway.... it may not even get to that.

interference