- Two pivotal Phase 3 clinical trials completed successfully in patients with chronic hepatitis C -

- Regulatory submissions planned for fourth quarter 2009 -
ROCKVILLE, Maryland - October 19, 2009 - Human Genome Sciences, Inc. (Nasdaq: HGSI) today announced that it has earned a $75 million milestone payment from Novartis, related to successful completion of the Phase 3 development program and the decision to submit applications seeking regulatory approval to market ZALBINTM (albinterferon alfa-2b) for the treatment of chronic hepatitis C.

HGS and Novartis have completed pre-submission meetings with the FDA and European regulatory agencies, and plan to submit marketing authorization applications for albinterferon alfa-2b, an investigational treatment for chronic hepatitis C, in the fourth quarter of 2009. HGS and Novartis have selected ZALBIN as the brand name for albinterferon-alfa 2b (formerly Albuferon®) in the United States. JOULFERON® has been selected as the brand name in the rest of the world. These brand names will be subject to confirmation by health authorities at the time of product approval.

"We are pleased with the progress of this program and look forward to continuing to work closely with Novartis to advance ZALBIN to the market," said H. Thomas Watkins, President and Chief Executive Officer, HGS. "Submission of global marketing authorization applications for ZALBIN and JOULFERON is planned for later this quarter. Assuming licensure by the FDA and other regulatory agencies, HGS believes ZALBIN could become a market-leading treatment for chronic hepatitis C."

About the Collaboration with Novartis

Under an exclusive worldwide co-development and commercialization agreement entered into in 2006, HGS and Novartis will co-commercialize albinterferon alfa-2b in the United States under the brand name ZALBINTM, and will share clinical development costs, U.S. commercialization costs and U.S. profits equally. Novartis will be responsible for commercialization of albinterferon alfa-2b in the rest of the world under the brand name JOULFERON®, and will pay HGS a royalty on those sales. HGS has primary responsibility for the bulk manufacture of albinterferon alfa-2b, and Novartis will have responsibility for commercial manufacturing of the finished drug product. Clinical development, commercial milestone and other payments to HGS could total as much as $507.5 million, including $132.5 million received previously and a $75 million payment expected in fourth quarter 2009. The remaining payments to HGS under the agreement relate to the achievement of certain regulatory approval and commercial milestones.

About ZALBIN (albinterferon alfa-2b)

ZALBIN (also known as JOULFERON) is a genetic fusion of human albumin and interferon alfa created using proprietary HGS albumin-fusion technology. Human albumin is the most prevalent naturally occurring blood protein in the human circulatory system, persisting in circulation in the body for approximately 19 days. Research has shown that genetic fusion of therapeutic proteins to human albumin decreases clearance and prolongs the half-life of the therapeutic proteins.

ZALBIN dosed once every two weeks has completed Phase 3 development. In April 2009, positive Phase 3 results of ZALBIN in patients with chronic hepatitis C were presented at the 44th annual meeting of the European Association for the Study of the Liver in Copenhagen. Data from two pivotal Phase 3 trials, ACHIEVE 1 and ACHIEVE 2/3, showed that ZALBIN met its primary endpoint of non-inferiority to Pegasys (peginterferon alfa-2a). With half the injections, ZALBIN achieved a rate of sustained virologic response comparable to Pegasys in these studies; rates of serious and/or severe adverse events were also comparable.

In addition, Novartis is currently conducting a Phase 2b trial to evaluate ZALBIN/JOULFERON dosed once every four weeks.

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 and cancer.

The Company's primary focus is rapid progress toward the commercialization of its two lead drugs, BENLYSTATM (belimumab) for lupus and ZALBINTM (albinterferon alfa-2b) for hepatitis C. BENLYSTA has successfully met its primary endpoint in the first of two Phase 3 trials in systemic lupus erythematosus, and results of the second BENLYSTA Phase 3 trial are expected in November 2009. ZALBIN has now completed Phase 3 development, and the submission of global marketing applications is expected in fourth quarter 2009.

In May 2009, HGS submitted a Biologics License Application to the FDA for raxibacumab for the treatment of inhalation anthrax. In July 2009, the Company secured a new purchase order for 45,000 doses of raxibacumab to be delivered to the U.S. Strategic National Stockpile over a three-year period, beginning near the end of 2009. The Company also has several drugs in earlier stages of clinical development for the treatment of cancer, led by the TRAIL receptor antibody HGS-ETR1 (mapatumumab) and a small-molecule antagonist of IAP (inhibitor of apoptosis) proteins. In addition, HGS has substantial financial rights to certain products in the GSK clinical pipeline including darapladib, currently in Phase 3 development in patients with coronary heart disease, and Syncria® (albiglutide), currently in Phase 3 development in patients with type 2 diabetes.

For more information about HGS, please visit the Company's web site at Health professionals and patients interested in clinical trials of HGS products may inquire via e-mail to [email protected] e-mail address is being protected from spam bots, you need JavaScript enabled to view it or by calling HGS at (877) 822-8472.

HGS, Human Genome Sciences, Albuferon, BENLYSTA, and ZALBIN 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 Human Genome Sciences' unproven business model, its dependence on new technologies, the uncertainty and timing of clinical trials, Human Genome Sciences' 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, Human Genome Sciences' 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 SEC. 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.