David P. Southwell has served as a member of PTC’s board of directors since December 2005. Mr. Southwell is currently the Chief Executive Officer of TScan Therapeutics, an oncology-focused cell therapy biotechnology company. He served as President and Chief Executive Officer and member of the Board of Directors of Inotek Pharmaceuticals from August 2014 until its merger with Rocket Pharmaceuticals in January 2018, where he remains on the Board of Directors. Mr. Southwell served as the Executive Vice President and Chief Financial Officer of Human Genome Sciences, a biopharmaceutical company, from March 2010 to its merger with Glaxo SmithKline in September 2012, and from 2008 to 2010 served as a member of the company’s board of directors. Prior to joining Human Genome Sciences, he served as Executive Vice President and Chief Financial Officer of Sepracor, Inc., a research-based pharmaceutical company, from June 1994 to March 2008. From August 1988 until 1994, Mr. Southwell was with Lehman Brothers Inc., a securities firm, in various positions with the investment banking division. Mr. Southwell serves on the board of directors of Rocket Pharmaceuticals and TScan Therapeutics, Inc. Mr. Southwell received a B.A. from Rice University and an M.B.A. from the Tuck School of Business at Dartmouth College, where he serves on the Board of Advisers.