This is for oncology but the basic idea tends to hold up...

https://www.thestreet.com/story/12696926/1/the-feuerstein-ratain-rule-update-still-perfect-predicting-small-cap-cancer-drug-failure.html

A bit dated, the $300 Million hurdle might need to be $400 million today

"A market cap under $300 million forecasts phase III study failure"