Jonathan Leff has served as a member of the ARS Board since September 2018. Mr. Leff has also served as a member of the board of directors of Larimar Therapeutics, Inc. (Nasdaq: LRMR), clinical-stage biotechnology company focused on developing treatments for complex rare diseases, since May 2020, and its predecessor, Chondrial Therapeutics, Inc., from December 2016 until May 2020. Mr. Leff is a partner at Deerfield Management Company, L.P. and Chairman of the Deerfield Institute. He joined Deerfield in 2013 and focuses on venture capital and structured investments in biotechnology and pharmaceuticals.

Prior to Deerfield, Mr. Leff served as Managing Director at Warburg Pincus LLC, a private equity company, from 2000 to 2012, where he led the firm’s investment efforts in biotechnology and pharmaceuticals. Mr. Leff also previously served as a member of the Executive Committee of the Board of the National Venture Capital Association (“NVCA”) and led NVCA’s life sciences industry efforts as Chair of NVCA’s Medical Innovation and Competitiveness Coalition.

He also served on the Emerging Companies Section Board of the Biotechnology Industry Organization. Mr. Leff is a board member of several not-for-profit organizations, including the Spinal Muscular Atrophy Foundation, Reagan-Udall Foundation and the Columbia University Medical Center Board of Advisors. He also previously served on the boards of several other publicly-traded biotechnology and pharmaceutical companies, including Proteon Therapeutics, Inc. (formerly Nasdaq: PRTO), a biopharmaceutical company developing pharmaceuticals for patients with renal and vascular diseases, from 2017 to 2019, AveXis, Inc. (formerly Nasdaq: AVXS), a biotechnology company that develops treatments for rare neurological genetic disorders, from 2014 to 2017 and Nivalis Therapeutics, Inc. (Nasdaq: NVLS), a clinical-stage pharmaceutical company developing a class of disease modifying therapies, from 2014 to 2016. Mr. Leff currently also serves on the boards of several private biopharmaceutical companies and has previously served on the boards of other privately held biopharmaceutical companies. Mr. Leff received an A.B. from Harvard University, a M.B.A. from the Stanford University Graduate School of Business and a M.S. from John Hopkins University.