 He served as chairman and chief executive officer of Affinium Pharmaceuticals, Ltd., which was founded by Tak Wah Mak, Aled Edwards, Cheryl Arrowsmith and Jack Greenblatt and since acquired by Debiopharm Group for Phase 2 asset based on a novel antibiotic target.Mendlein served as the CEO of Adnexus Therapeutics, a Boston, Massachusetts-based biotech company founded by Flagship Ventures and acquired by Bristol-Myers Squibb () for over $500M in 2008.The technology platform was based on the work of Jack W. Szostak, 2009 Nobel Laureate for Physiology or Medicine.