Human Genome Sciences Advances Oncology Portfolio

ROCKVILLE, Md., April 16 /PRNewswire-FirstCall/ -- Human Genome Sciences, Inc. (Nasdaq: HGSI) today announced that it has reacquired rights to the TRAIL receptor antibodies HGS-ETR1 (mapatumumab) and HGS-ETR2 (lexatumumab) from GlaxoSmithKline (GSK), in return for a reduction in royalties due to HGS if Syncria(R) (albiglutide) is commercialized. HGS is developing its TRAIL receptor antibodies for the treatment of a broad range of cancers, and announced today that it plans to initiate its third randomized Phase 2 chemotherapy combination trial of HGS-ETR1 by mid-2008 in patients with hepatocellular cancer.

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"As our Phase 3 products near commercialization, we are investing strategically to bring our next products forward," said H. Thomas Watkins, President and Chief Executive Officer, HGS. "We are building our oncology portfolio around our leading expertise in the apoptosis pathway. We have added IAP inhibitors, which are highly complementary to our TRAIL receptor antibodies. We have initiated new chemotherapy combination trials of HGS-ETR1, and we have now reacquired the rights to our TRAIL receptor antibodies."

The GSK rights to the TRAIL receptor antibodies resulted from a June 1996 agreement under which HGS granted a 50/50 co-development and co-promotion option to GSK for certain human therapeutic products that complete Phase 2a clinical trials. In exchange for reacquiring the rights to its TRAIL receptor antibodies, HGS has agreed to a reduction in the royalties to which it is entitled from GSK if Syncria is commercialized. The fees and milestone payments due to HGS under the original Syncria agreement, some of which have already been received, could amount to as much as $183 million and remain unchanged in the amended agreement. Syncria, a novel long-acting form of GLP-1 (glucagon-like peptide-1), was created by HGS using its proprietary albumin-fusion technology. GSK has exclusive rights to develop and commercialize Syncria, and is developing it for use in the treatment of type 2 diabetes. HGS believes it is possible that GSK will reach a decision in 2008 regarding whether to advance Syncria to Phase 3 development.

"We view our oncology portfolio as the cornerstone of our mid-stage pipeline, and as a key driver of future growth beyond the launch of our late- stage products," said Barry A. Labinger, Executive Vice President and Chief Commercial Officer, HGS. "Reacquiring the rights to our TRAIL antibodies gives us the opportunity to drive and advance this growing program. We will continue to explore the possibility of bringing in additional new products, as well as forming new partnerships to add expertise and near-term financial resources in support of our pipeline."

HGS reported that a 2002 agreement with the Pharmaceutical Division of Kirin Brewery Company, Ltd. for joint development of antibodies to TRAIL receptor 2 has also been terminated.

About the HGS-ETR1 Proof-of-Concept Program

HGS-ETR1 is the most advanced of any product in development that targets the TRAIL apoptosis pathway. HGS has advanced HGS-ETR1 to a proof-of-concept phase consisting of three randomized Phase 2 chemotherapy combination trials to evaluate its potential in the treatment of specific cancers:

About the HGS IAP Inhibitor Program

In December 2007, the HGS oncology portfolio was further strengthened by a licensing and collaboration agreement between HGS and Aegera Therapeutics Inc. This agreement provides HGS with exclusive worldwide rights (excluding Japan) to develop and commercialize HGS1029 (formerly AEG40826) and other small- molecule inhibitors of IAP (inhibitor of apoptosis) proteins in oncology. Preclinical studies of HGS1029 in combination with the Company's TRAIL receptor antibodies demonstrated dramatic synergistic activity against a number of cancer types. HGS1029 has also shown significant anti-tumor activity alone and in combination with other agents in a broad range of cancers. HGS expects to initiate a Phase 1 clinical trial of HGS1029 by mid-2008 and plans to develop its TRAIL receptor antibodies and IAP inhibitors in combination with one another and in combination with other therapeutic agents.

About HGS-ETR1 and HGS-ETR2

HGS-ETR1 and HGS-ETR2 are agonistic human monoclonal antibodies that directly induce cancer-cell death by specifically binding to and activating the proteins known as TRAIL receptors 1 and 2, respectively. Using genomic techniques, HGS originally identified the TRAIL receptor 1 and 2 proteins. HGS is developing its TRAIL receptor antibodies as potential treatments for a broad range of cancers.

Conference Call

HGS management will hold a conference call to discuss this announcement today at 5 PM Eastern time. Participants may listen to the call by dialing 800-930-1344 or 913-312-1416, passcode 8678241, five to 10 minutes before the start of the call. A replay of the conference call will be available for several days by dialing 888-203-1112 or 719-457-0820, passcode 8678241. This conference call also will be webcast. Interested parties who wish to listen to the webcast should visit the Human Genome Sciences website at The archive of the conference call will be made available within a few hours after the call and will remain available for several days.

About Human Genome Sciences

The mission of HGS is to apply great science and great medicine to bring innovative drugs to patients with unmet medical needs.

The HGS clinical development pipeline includes novel drugs to treat hepatitis C, lupus, inhalation anthrax, cancer and other immune-mediated diseases. The Company's primary focus is rapid progress toward the commercialization of its two key lead drugs, Albuferon(R) for hepatitis C and LymphoStat-B(R) (belimumab) for lupus. Phase 3 clinical trials of both drugs are ongoing.

ABthrax(TM) (raxibacumab) is in late-stage development for the treatment of inhalation anthrax, and the Company is on track to begin the delivery in fall 2008 of 20,000 doses of ABthrax to the Strategic National Stockpile under a contract entered into with the U.S. Government in June 2006. Other HGS drugs in clinical development include two TRAIL receptor antibodies for the treatment of cancer. HGS1029, a small-molecule antagonist of IAP (inhibitor of apoptosis) proteins, is expected to enter Phase 1 clinical trials for the treatment of cancer by mid-2008. In addition, HGS has substantial financial rights to certain products in the GlaxoSmithKline clinical development pipeline.

For more information about HGS, please visit the Company's web site at Health professionals and patients interested in clinical trials of HGS-ETR1, HGS-ETR2 or other HGS products may inquire via e-mail to [email protected] or by calling HGS at (301) 610-5790, extension 3550.

HGS, Human Genome Sciences, ABthrax, Albuferon and LymphoStat-B are trademarks of Human Genome Sciences, Inc.

Safe Harbor Statement

This announcement contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. The forward-looking statements are based on Human Genome Sciences' current intent, belief and expectations. These statements are not guarantees of future performance and are subject to certain risks and uncertainties that are difficult to predict. Actual results may differ materially from these forward-looking statements because of the Company's unproven business model, its dependence on new technologies, the uncertainty and timing of clinical trials, the Company's ability to develop and commercialize products, its dependence on collaborators for services and revenue, its substantial indebtedness and lease obligations, its changing requirements and costs associated with facilities, intense competition, the uncertainty of patent and intellectual property protection, the Company's dependence on key management and key suppliers, the uncertainty of regulation of products, the impact of future alliances or transactions and other risks described in the Company's filings with the Securities and Exchange Commission. In addition, the Company will continue to face risks related to animal and human testing, to the manufacture of ABthrax and to FDA concurrence that ABthrax meets the requirements of the ABthrax contract. If the Company is unable to meet the product requirements associated with the ABthrax contract, the U.S. government will not be required to reimburse the Company for the costs incurred or to purchase any ABthrax doses. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of today's date. Human Genome Sciences undertakes no obligation to update or revise the information contained in this announcement whether as a result of new information, future events or circumstances or otherwise.

SOURCE Human Genome Sciences, Inc.