Don currently serves as Chairman of the Board of several biopharmaceutical companies, including Tentarix Biotherapeutics and Ocelot Bio, and also served as Chairperson of the Board for Oyster Point Pharma prior to their acquisition by Viatris in January 2023. Prior to these roles, he served as Executive Chairman and interim Chief Executive Officer of Adicet Bio, Inc. Mr. Santel was also Chief Executive Officer and board member for Hyperion Therapeutics, Inc., and a co-founder, board member and Chief Executive Officer for CoTherix, Inc., a biopharmaceutical company focused on developing therapies for cardiopulmonary disease, including PAH.