On May 11, 2020, Lesley Ann Calhoun, Senior Vice President, Finance and principal accounting officer of Global Blood Therapeutics, Inc. (the “Company”), delivered notice of her resignation from these positions and from her employment with the Company, to be effective on May 29, 2020 (the “Calhoun Resignation”), in order to pursue a leadership opportunity with a privately-held healthcare company. Ms. Calhoun’s resignation is not due to any disagreement with the Company on any matter relating to the Company’s operations, financial statements, internal controls, auditors, policies or practices. On May 13, 2020, the Board of Directors of the Company appointed Jeffrey Farrow, the Company’s Chief Financial Officer, as principal accounting officer of the Company, effective upon the Calhoun Resignation. Mr. Farrow, 58, has served as the Company’s Chief Financial Officer and principal financial officer since April 2016. Mr. Farrow previously served as chief financial officer of ZS Pharma, Inc. Prior to ZS Pharma, he served as the chief financial officer at Hyperion Therapeutics, Inc., from July 2010 until May 2015 where he was part of the team responsible for the successful regulatory approval and commercial launch of RAVICTI® for the treatment of urea cycle disorders.