GlaxoSmithKline and Human Genome Sciences announce FDA extension of Benlysta® PDUFA target date to 10th March 2011

Issued: London, UK

GlaxoSmithKline PLC (GSK) and Human Genome Sciences, Inc. (Nasdaq: HGSI) today announced that the U.S. Food and Drug Administration (FDA) has extended the Prescription Drug User Fee Act (PDUFA) target date for its priority review of the Biologics License Application (BLA) for Benlysta® (belimumab) as a potential treatment for systemic lupus erythematosus (SLE) from 9^th December 2010 to 10^th March 2011.

After the FDA Arthritis Advisory Committee met on 16 November 2010 to consider the Benlysta BLA , the FDA requested some additional information from HGS, which has been submitted.

Belimumab is an investigational drug and the first in a new class of drugs called BLyS-specific inhibitors. HGS and GSK are developing belimumab under a definitive co-development and co-commercialization agreement entered into in 2006.

About GlaxoSmithKline

GSK Biopharm R&D is employing novel approaches to harness the therapeutic potential of biopharmaceuticals for the benefit of patients with serious autoimmune disease.

GlaxoSmithKline – one of the world’s leading research-based pharmaceutical and healthcare companies – is committed to improving the quality of human life by enabling people to do more, feel better and live longer. For further information please visit www.gsk.com

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 www.hgsi.com. Health professionals and patients interested in clinical trials of HGS products may inquire via e-mail to medinfo@hgsi.com or by calling HGS at (877) 822-8472.

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

Cautionary statement regarding forward-looking statements
Under the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995, GSK cautions investors that any forward-looking statements or projections made by GSK, including those made in this announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Factors that may affect GSK' s operations are described under 'Risk Factors' in the 'Business Review' in the company' s Annual Report on Form 20-F for 2009.

HGS 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.