[gamblor956]

The drug is based on a molecule he discovered while working at Pfizer

On leaving the company, he acquired the intellectual property [IP] rights from his former employer

A lot of people don't do this when they leave or are terminated. It doesn't usually succeed, but it's always worth at least making the attempt. (In this case, Pfizer gave him the IP rights to the molecule he discovered in exchange for a portion of his company.)