ROCKVILLE, Maryland - June 14, 2010 - Human Genome Sciences, Inc. (Nasdaq: HGSI) today announced that it has received preliminary written feedback from the U.S. Food and Drug Administration (FDA) regarding the Company's Biologics License Application (BLA) seeking approval in the United States to market 900-mcg ZALBINTM (albinterferon alfa-2b, known in Europe as JOULFERON®) dosed every two weeks for the treatment of chronic hepatitis C. FDA has expressed concerns regarding the risk benefit assessment of ZALBIN dosed at 900-mcg every two weeks. Although the BLA review is ongoing, HGS has concluded that licensure of this dosing regimen is unlikely.

The FDA feedback was provided via a Discipline Review letter, which is a standard vehicle for review disciplines (e.g., clinical) to convey early thoughts on possible deficiencies of an application. In April 2010, HGS announced that Novartis withdrew its Marketing Authorization Application for JOULFERON from the European Medicines Agency.

ZALBIN (JOULFERON) is being developed by HGS and Novartis under an exclusive worldwide co-development and commercialization agreement entered into in 2006. HGS and Novartis are considering development of ZALBIN dosed every four weeks, and HGS previously reported the positive interim results of a Phase 2b study of this ZALBIN regimen.

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.

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.

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 and ZALBIN are trademarks of Human Genome Sciences, Inc. Other trademarks referenced are the property of their respective owners.

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 and regulatory approvals, 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.