GSK provides update on Herpevac trial for women evaluating Simplirix™ (Herpes Simplex Vaccine)

Issued: London UK

GlaxoSmithKline (GSK) has made the decision not to pursue further worldwide development of Simplirix™ (Herpes Simplex Vaccine), an experimental vaccine intended to prevent genital herpes disease in women.

The decision was made following receipt of the results of the Herpevac Trial for Women, a Phase III trial evaluating efficacy of Simplirix™, which was conducted collaboratively with the US National Institute of Allergy and Infectious Diseases (NIAID), part of the US National Institutes of Health (NIH).

The trial began in 2002 and 8,323 women ages 18-30 were vaccinated at 50 sites in the United States and Canada. An assessment of the final trial results showed that the vaccine had an acceptable safety profile, but the primary trial endpoint, prevention of genital herpes disease, was not met. GSK and NIH continue to evaluate data from the trial and plan to present details of the analysis in the near future in an appropriate scientific forum.

Gary Dubin, Vice President and Director, Late Clinical Development at GlaxoSmithKline Biologicals commented: “We would like to express our gratitude towards our partner NIAID for their proactive collaboration and substantial contribution in the program and the volunteers for their participation in the study.”

For further information please visit www.niaid.nih.gov/news/newsreleases/2010/Pages/Herpevac.aspx

and Q&A: www.niaid.nih.gov/news/QA/pages/HerpevacQA.aspx

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

GlaxoSmithKline Biologicals (GSK Biologicals), GlaxoSmithKline’s vaccines business, is one of the world’s leading vaccine companies and a leader in innovation. The company is active in vaccine research, development and production with over 30 vaccines approved for marketing and 20 more in development - both in the prophylactic and therapeutic fields

Simplirix™ is a registered trademark of the GlaxoSmithKline group of companies.

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.