Howard H. Pien has served as a director of ImmunoGen since 2009. Mr. Pien has most recently served as Chairman of the Board and Chief Executive Officer of Medarex, Inc. from 2007 to its acquisition by Bristol-Myers Squibb Company in 2009. Prior to that he was a private consultant from 2006 to 2007. Prior to that he served as President and Chief Executive Officer of Chiron Corporation from 2003 to its acquisition by Novartis AG in 2006. Prior to that he served in various executive capacities at GlaxoSmithKline plc (GSK) and its predecessor companies, including as President of GSK’s International Pharmaceuticals business from 2000 to 2003, and as President of Pharmaceutical Operations of SmithKline Beecham plc (a predecessor of GSK). Mr. Pien also worked for six years at Abbott Laboratories and for five years at Merck & Co., Inc. in positions in sales, market research, licensing and product management. Mr. Pien is also currently an advisor to the life sciences practice of Warburg Pincus, a private equity firm, as well as a director of Indivior PLC (as non-executive chairman), Juno Therapeutics, Inc. (as non-executive chairman), Sage Therapeutics, Inc. and Vanda Pharmaceuticals, Inc.