Human Genome Sciences Responds To GSK Extension of Unsolicited Tender Offer; Board of Directors Reject Offer

Human Genome Sciences, Inc.

today issued the following statement regarding the extension by GlaxoSmithKline plc

of its unsolicited tender offer to acquire all the outstanding common shares of HGS at a price of $13.00 per share in cash and GSK's statement that approximately 375,526 shares of HGS common stock have been tendered into their offer. HGS noted that less than one percent of its shares outstanding tendered into the GSK offer. The HGS Board of Directors has rejected GSK's unsolicited $13.00 per share tender offer after determining, in consultation with financial and legal advisors, that the GSK offer price is inadequate and does not reflect the value inherent in HGS. As previously announced, our Board has authorized the exploration of strategic alternatives in the best interests of stockholders, including a potential sale of the Company, and has set a bid date of July 16, 2012 for the submission of definitive proposals to acquire all outstanding common shares of HGS. This process continues to be active and fully underway. Although HGS continues to welcome GSK's participation, GSK has twice declined to enter the process. We are committed to completing our exploration of strategic alternatives as expeditiously as possible and in a manner that ensures that HGS stockholders have the benefit of a complete and fair process. The HGS Board of Directors recommends that HGS stockholders reject GSK's tender offer and not tender any of their shares to GSK.