|In addition to what you quoted of the FDA's guidance, it continues to say that one of the ways to demonstrate substantial improvement is:|
"The new drug has an important safety advantage that relates to serious adverse reactions (e.g., those that may result in treatment interruption) compared with available therapies and has similar efficacy."
That would appear to be 132's path to BTD.
FWIW, statistically the chance is not great: In the first 3 quarters of the federal fiscal year beginning Oct 1 2018, the FDA received 118 BTD requests. 36 were granted, 46 denied, and the rest are pending. On the other hand, in mUC, 9 drugs since 2014 have received BTD.
Considering the way things are moving toward targeted therapies, I think targeting Trop2 in mUC would guarantee 132's chance at BTD and position it better vs EV. Trop2 is expressed in 83% of mUC. Eliminating those 17% of patients that wont respond will elevate the ORR on par with EV. And it would be better for patients. I wonder if they collected tissue samples for a post hoc look (they are doing that in the prostate study).
Then again, what company schedules an investor event if the data isn't impressive?