ROCKVILLE, Maryland – May 30, 2008 – Human Genome Sciences, Inc. (Nasdaq: HGSI) today announced that it has initiated dosing in a Phase 1 clinical trial to evaluate the safety and tolerability of its lead IAP inhibitor, HGS1029, as monotherapy in patients with advanced solid tumors.

“We are pleased to initiate this first human study of HGS1029, and we look forward to studying our IAP inhibitors both alone and in combination with other anti-cancer agents, including our TRAIL receptor antibodies,” said Gilles Gallant, B. Pharm., Ph.D., Vice President, Clinical Research - Oncology, HGS.

HGS acquired exclusive worldwide rights (excluding Japan) to develop and commercialize HGS1029 (formerly AEG40826) and other IAP inhibitors from Aegera Therapeutics, Inc. in December 2007. When IAP proteins are over-expressed in cancer cells, they may help cancer cells resist apoptosis, or programmed cell death, and resume growth. The IAP inhibitors developed by Aegera, including HGS1029, are members of a new class of designed small-molecule drugs that block the biological activity of IAP proteins, thus allowing apoptosis to proceed and causing the cancer cells to die. Preclinical studies have shown that HGS1029 has significant anti-tumor activity alone and in combination with other anti-cancer agents, including the HGS TRAIL receptor antibodies, against a number of cancer types.

About the Phase 1 Trial Design

The primary objectives of the Phase 1 open-label, dose-escalation study are to evaluate the safety and tolerability of HGS1029 as monotherapy in patients with advanced solid tumors, and to select a recommended dose for Phase 2 studies. Secondary objectives include documenting possible anti-tumor activity and determining HGS1029’s pharmacokinetic profile. HGS1029 will be administered as a 15-minute infusion once weekly for 3 consecutive weeks followed by a week off. Up to 40 patients will be treated in the study, with 15-20 patients treated in the dose-escalation phase.

About the HGS Oncology Portfolio

HGS is investing strategically to expand and advance its oncology portfolio around its leading expertise in the apoptosis pathway. HGS has initiated new chemotherapy combination trials of HGS-ETR1 (mapatumumab), added the new opportunity to develop and commercialize HGS1029 and other IAP inhibitors, and reacquired the rights to its TRAIL receptor antibodies. HGS-ETR1, the Company’s antibody to TRAIL receptor 1, is the most advanced of any product in development that targets the TRAIL apoptosis pathway.

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® for hepatitis C and LymphoStat-B® (belimumab) for lupus. Phase 3 clinical trials of both drugs are ongoing.

ABthrax™ (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 and a small-molecule antagonist of IAP (inhibitor of apoptosis) proteins for the treatment of cancer. In addition, HGS has substantial financial rights to three products in the GlaxoSmithKline clinical development pipeline.

For more information about HGS, please visit the Company’s web site at www.hgsi.com. Health professionals and patients interested in clinical trials of HGS products may inquire via e-mail to This e-mail address is being protected from spam bots, you need JavaScript enabled to view it 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, and we will not receive any of the expected revenues relative to ABthrax. 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. ###