Elizabeth Trehu has been named the new chief medical officer of Cambridge, MA-based Jounce Therapeutics. Trehu is a veteran of the Boston biotech scene. She was most recently the CMO of Promedior, and had executive roles at Infinity Pharmaceuticals (NASDAQ: INFI), Genzyme, and Millennium Pharmaceuticals before that. Bristol-Myers Squibb recently paid $150 million for an option to potentially acquire Promedior later on. Jounce, meanwhile, raised a $56 million round earlier this year and looks headed for an IPO.