Board of Directors

Executive Chairman

John F. Milligan, PhD has served as the Executive Chairman of our board of directors since August 2020. Dr. Milligan had a 29-year career with Gilead, retiring as President and Chief Executive Officer in December 2018. During his tenure at Gilead, he led teams that developed, manufactured and commercialized more than 25 new therapies for significant unmet needs, including the first single tablet regimen for HIV treatment and the first 12 week, all oral cure for HCV. John led multiple transformative acquisitions including Triangle Therapeutics in 2003, Myogen in 2006, CV Therapeutics in 2009, Pharmassett in 2012 and Kite in 2017. Before taking the CEO role, as CFO, John built a robust international organization that allowed the company to grow from $190 million in revenue to over $4.2 billion in just six years.


He helped the company become a global organization with direct operations in 44 countries that was able to deliver its medicines to more than 10 million patients every day. He joined Gilead when it was a private company with 32 employees, and upon retirement, 29 years later, Gilead had over 11,000 employees, sales of over $21 billion and a market cap of $85 billion. In addition to his role as executive chairman of 4DMT, John is currently a board member of Pacific Biosciences of California (Nasdaq: PACB), serving on the audit and compensation committees. John also serves as the Chair of the Board of Trustees of Ohio Wesleyan University.


Chief Executive Officer
Co-Founder, President

David Kirn, M.D., is our co-founder and has served as our Chief Executive Officer and Chairman of our board of directors since our inception in 2013. Dr. Kirn is an Adjunct Professor of Bioengineering at U.C. Berkeley. He currently serves as Executive Chairman of the board of the following privately held company: Ignite Immunotherapy Inc., where he is a co-founder. Dr. Kirn held senior development positions at Onyx Pharmaceuticals and Celgene, and he was a senior advisor on viral vector gene therapeutics and cancer immunotherapy for over 10 years with numerous companies, including Biogen Idec, Novartis, Cell Genesys, Pfizer and Bayer.




Dr. Kirn received a B.A. in Physiology (Departmental Citation; Phi Beta Kappa) from U.C. Berkeley in 1985, an M.D. (Alpha Omega Alpha) from U.C. San Francisco Medical School in 1989 and completed internal medicine residency training at Harvard Medical School, Brigham and Women’s Hospital (including a term as Chief Medical Resident at affiliated VA hospital). He has also completed hematology-oncology and clinical research fellowships at U.C. San Francisco and completed a certificate of business excellence from the Haas Business School at U.C. Berkeley. In 2013, he was awarded the Johnson & Johnson Entrepreneur Innovator award from the J&J Innovation Center.


Co-Founder, Chief Scientific Advisor

David Schaffer, Ph.D. is our co-founder and has served as our Chief Scientific Advisor and a member of our board of directors since our inception in 2013. Dr. Schaffer has served as a Professor of Chemical and Biomolecular Engineering, Bioengineering, Molecular and Cell Biology, and the Helen Wills Neuroscience Institute at the U.C. Berkeley since 1999 and has served as the Director of the Berkeley Stem Cell Center since 2011.



He currently serves on the board of directors of the following publicly-held company: uniQure NV since January 2014. Dr. Schaffer received a B.S. in Chemical Engineering from Stanford University in 1993. He earned his Ph.D. in Chemical Engineering from the Massachusetts Institute of Technology in 1998.


Board Member

Charles Theuer, M.D., Ph.D., has served as a member of our board of directors since December 2015. Dr. Theuer has served as President and Chief Executive Officer at Tracon Pharmaceuticals, Inc., since June 2006. He previously served as Chief Medical Officer at TargeGen Pharmaceuticals, Inc. until June 2006.



He currently serves on the board of directors of the following publicly-held companies: Tracon Pharmaceuticals Inc., since June 2006 and Oncternal Therapeutics Inc. since May 2018, where he serves on the Science and Development and Nominating and Corporate Governance committees. Dr. Theuer received a B.S. in Life Sciences from the Massachusetts Institute of Technology in 1985. He received his M.D. from U.C. San Francisco in 1989. He received his Ph.D. in Environmental Health Science from U.C. Irvine in 2002.


Board Member

Jacob Chacko, M.D., MBA, has served as a member of our board of directors since March 2019. Dr. Chacko has served as Chief Executive Officer of ORIC Pharmaceuticals, Inc., a clinical-stage oncology company focused on discovery and development of novel therapies against treatment-resistant cancers, since May 2018. Prior to ORIC, Dr. Chacko served as Chief Financial Officer of Ignyta, Inc., a publicly traded precision oncology company, from May 2014 until February 2018 when Ignyta was acquired by Roche Holdings, Inc. Prior to Ignyta, Dr. Chacko was Vice President at TPG Capital from August 2008 until May 2014. From 2002 until 2003, Dr. Chacko was a consultant serving healthcare clients at McKinsey & Company.



Dr. Chacko currently serves on the board of directors of Turning Point Therapeutics, Inc., a publicly-traded biotechnology company, from November 2018. Dr. Chacko served on the board of directors of RentPath Inc., a digital media company, from 2011 until 2014, Envision Pharmaceutical Services, LLC from 2013 until 2014, Bonti, Inc., a biotechnology company, from February 2018 until October 2018 and the Packard Children’s Health Alliance at the Lucile Packard Children’s Hospital Stanford from 2013 until June 2017. Dr. Chacko currently chairs the Western Regional Selection Committee for the Marshall Scholarship. Dr. Chacko concurrently received his M.D. from the U.C. Los Angeles and his M.B.A. from Harvard Business School. Dr. Chacko received a M.Sc. from Oxford University as a Marshall Scholar.


Board Member

Tony Yao, M.D., Ph.D. has served as a member of our board of directors since August 2018. Dr. Yao has served as portfolio manager of life science strategy at ArrowMark Partners since April 2012. He previously served as an equity analyst at Janus Capital Group until March 2012.




He currently serves on the board of directors of the following publicly-held company: Precision Biosciences since June 2018, where he serves on the compensation and audit committee. Dr. Yao received a B.S. in biochemistry from Brown University in 1994. He earned an M.D. and a Ph.D. in Immunology from Stanford University in 2002.


Board Member

Bill Burkoth, MBA, has served as a member of our board of directors since March 2019. Mr. Burkoth has served on the venture investments team of Pfizer Inc. since 2004 and currently serves as their executive director. Mr. Burkoth worked in business development at Galileo Pharmaceuticals, Inc. and at IntraBiotics Pharmaceuticals, Inc. from 2002 to 2004.



Mr. Burkoth worked as an analyst at Bay City Capital, a life sciences venture capital firm, from 1999 to 2002. He previously served on the board of directors of the following publicly-held company: NovoCure Limited from July 2009 to May 2019. Mr. Burkoth received a B.A. in Chemistry from Whitman College in 1999 and an M.B.A. from Columbia Business School in 2011.


Board Member

Susannah Gray has served as a member of our board of directors since July 2020. Ms. Gray brings more than 30 years of biopharmaceutical experience specifically in corporate finance and capital markets roles, most recently serving as EVP, Finance & Strategy of Royalty Pharma Management, LLC. Ms. Gray spent 14 years as executive vice president and chief financial officer of Royalty Pharma before retiring in 2019 just ahead of the Company’s initial public offering. At Royalty Pharma, Ms. Gray led the Company’s efforts to maximize its financial capabilities. In her career at Royalty Pharma, she increased the debt facilities from approximately $200 million to $7 billion, and was responsible for over $20 billion in total financing. She also raised $2.0 billion equity capital for the Company.




Prior to joining Royalty Pharma, Ms. Gray had a 14-year career in investment banking. In her most recent role, she was a managing director and the senior analyst covering the healthcare sector for CIBC World Market’s high yield group from 2002 to 2004. She worked in a similar capacity at Merrill Lynch prior to joining CIBC World Markets. Ms. Gray joined Merrill Lynch in April 1999 after nine years at Chase Securities (a predecessor of JP Morgan), working in various capacities within the high yield and the structured finance groups. Ms. Gray received a BA with honors from Wesleyan University and holds an MBA degree from Columbia University. Ms. Gray currently serves on the board of directors of Susan G. Komen and is on the board of trustees at Wesleyan University.