No BTD - In order for there to be a BTD the drug submitted has to demonstrate substantial improvement over available therapy on a clinically significant endpoint.

At the time data was gathered for the BTD leronlimab had median overall survival of 12.1+ months we hadn't hit mOS yet so it is somewhere over that amount, Trodelvy had 11.8 months. In progression free survival at 525mg leronlimab was 6.2 months vs. Trodelvy's 4.8 months.

Is that substantial? The FDA has approved drugs in highly deadly cancers because they've improved survivability by a few weeks.

Another thing the FDA takes into account is a significantly improved safety profile.

Here are the side effects of Trodelvy.

severe neutropenia
severe diarrhea
low white blood cell counts
anemia
nausea
fatigue
vomiting
hair loss
constipation
rash
decreased appetite
abdominal pain