On July 26, 2019, Mersana Therapeutics, Inc. announced that Wayne Foster, Vice President of Finance and the Company's principal accounting officer, would be departing the Company as of September 30, 2019, and in connection with that departure, Mr. Foster will stop serving as the Company's principal accounting officer following the filing of the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2019, timing for which will be publicly announced in the near term. As of that date, Ashish Mandelia, age 45, who was appointed Vice President, Controller in July 2019, will become the Company's new principal accounting officer. Mr. Mandelia previously served as Senior Director, Technical Accounting at TESARO, Inc., where he worked for more than two years. Prior to joining TESARO, Inc., Mr. Mandelia held roles of increasing responsibility over the course of 12 years at PwC in its Boston and London offices.