Jonathan Leff, M.D.
Jonathan Leff is a physician-scientist with a long history of drug development experience in the biotechnology and pharmaceutical industry. He currently serves as the Senior Vice President and Chief Medical Officer of Ascendis Pharma, a biotechnology company developing medicines for rare endocrine disorders. Prior to Ascendis, Dr. Leff served as Executive Vice President, Research and Development at InterMune (acquired by Roche/Genentech in 2014). At InterMune, Dr. Leff oversaw the development and US approval of Esbriet® (oral pirfenidone) for the treatment of idiopathic pulmonary fibrosis. Prior to InterMune, Dr. Leff served as Chief Medical Officer at KaloBios Pharmaceuticals, and Vice President and Chief Medical Officer at Halozyme Therapeutics. Prior to Halozyme, Dr. Leff was Vice President and Global Head of Inflammation Clinical Development at Roche, where he managed the worldwide clinical development programs for MabThera®/Rituxan®, ocrelizumab, and Actemra®. Dr. Leff also held various positions at Amgen, including Vice President, North American Medical Affairs. Prior to Amgen, Dr. Leff served at Merck developing and commercializing Singulair®.
Dr. Leff trained in Internal Medicine, Pulmonary and Critical Care at the University of Colorado in Denver and served in various positions, including director of the Outpatient Pulmonary Clinic. Dr. Leff holds a B.A. in Chemistry from the University of Pennsylvania, and received his M.D. from the University of Pennsylvania School of Medicine. He also serves as the Co-Chair of the Board of Trustees of the Bowman School, a Montessori school in Palo Alto, CA.