David R. Brennan is Chairman of Alexion’s Board of Directors. He served as a Director of Alexion since July 2014 and as Interim Chief Executive Officer of Alexion from December 2016 to March 2017.

From 2006 to 2012, he served as Chief Executive Officer and Executive Director of AstraZeneca PLC, one of the world's largest pharmaceutical companies. Mr. Brennan worked for AstraZeneca in increasing roles of responsibility, including as Executive Vice President of North America from 2001 to 2006, and as Senior Vice President of Commercialization and Portfolio Management from 1999 to 2001.

Prior to the merger of Astra AB and Zeneca Plc, he served as Senior Vice President of Business Planning and Development of Astra Pharmaceuticals LP, the American subsidiary of Astra AB. Mr. Brennan began his career in 1975 at Merck and Co. Inc., where he rose from Sales Representative in the U.S. Division to General Manager of Chibret International, a French subsidiary of Merck.

Mr. Brennan currently serves on the Board of Directors Insmed Incorporated, and previously served on the Board of Directors of AstraZeneca PLC, Innocol, Inc., Reed Elsevier PLC, and the Pharmaceutical Research & Manufacturers of America (PhRMA).

Mr. Brennan received a Bachelor of Arts in business administration from Gettysburg College, where he is a member of the Board of Trustees.

Mr. Brennan is a member of the Science and Innovation Committee.