New Drug Applications

Promacta

eltrombopag

Treatment for Idiopathic (Immune) Thrombocytopenic Purpura

FDA Grants Priority Review for Promacta

FDA Grants Priority Review for Promacta (eltrombopag)

PHILADELPHIA and LONDON, March 3, 2008 /PRNewswire-FirstCall/ -- GlaxoSmithKline today announced that the United States Food and Drug Administration has granted Priority Review for Promacta (eltrombopag) for the short-term treatment of patients with chronic idiopathic thrombocytopenic purpura (ITP). Promacta is an investigational, once-daily oral treatment that induces the production of cells in the bone marrow to generate platelets, which are critical in minimizing the incidence of bleeding in chronic ITP.

If approved, Promacta would be the first oral thrombopoeitin (TPO) receptor agonist for the short-term treatment of previously treated patients with chronic ITP to increase platelet counts and reduce bleeding.

"Our goal for Promacta is to make available a targeted therapy in oral form for patients to help raise their platelet counts without having to suppress the immune system," said Paolo Paoletti, M.D., Senior Vice President of the Oncology Medicine Development Center at GSK. "The FDA designation of our submission for priority review is very encouraging and brings us closer to offering physicians and their patients Promacta."

The priority review designation means FDA is expected to make a decision on the NDA for the investigational compound within six months of the submission.

In pivotal studies, the most common adverse events observed in patients taking Promacta were headache, nausea, nasopharyngitis, diarrhea and vomiting.

GSK also plans to submit a Marketing Authorization Application (MAA) for eltrombopag in the treatment of chronic ITP in Europe in 2008 where it will be marketed as REVOLADE. The compound is also being studied for long-term treatment of chronic ITP, as well as thrombocytopenia associated with Hepatitis C Virus cirrhosis and chemotherapy induced thrombocytopenia.

About ITP

Chronic ITP is a disorder marked by increased platelet destruction and/or inadequate platelet production in the blood, which causes an increased risk of bruising and bleeding.(1,2) There are estimated to be approximately 60,000 individuals diagnosed with chronic ITP in the U.S.(3) People with chronic ITP often bleed from small blood vessels causing bruises, nosebleeds or even fatal gastrointestinal or intra cerebral bleeds, although these are rare.(1)

About Promacta (eltrombopag)

Eltrombopag is an oral, non-peptide thrombopoietin receptor agonist that has been shown in pre-clinical research and clinical trials to stimulate the proliferation and differentiation of megakaryocytes, the bone marrow cells that give rise to blood platelets. Eltrombopag was discovered as a result of research collaboration between GlaxoSmithKline and Ligand Pharmaceuticals . It is being developed by GlaxoSmithKline. Eltrombopag is an investigational compound that has not received regulatory approval in any market for any indication at this time.

About GlaxoSmithKline

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 company information, visit GlaxoSmithKline at www.gsk.com.

Cautionary statement regarding forward-looking statements

Under the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995, the company cautions investors that any forward-looking statements or projections made by the company, 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 the Group's operations are described under 'Risk Factors' in the 'Business Review' in the company's Annual Report on Form 20-F for 2006.

To access the latest GSK news, visit http://us.gsk.com/.

Enquiries:

References:

(1)National Heart, Lung, and Blood Institute. Diseases and Conditions Index. http://www.nhlbi.nih.gov/health/dci/Diseases/Itp/ITP_WhatIs.html. Accessed November 12, 2007.

(2)Cines DB, Blanchette V. Idiopathic thrombocytopenic purpura. N Engl J Med. 2002;364: 995-1008.

(3)Feudjo-Tepie M, Robinson N, Bennett D. Prevalence estimates of adult chronic idiopathic thrombocytopenic purpura (ITP). J Thromb Haemost. 2008 doi: 10.1111/j.1538-7836.2008.02911.x.

CONTACT: Jeff McLaughlin of GlaxoSmithKline, +1-919-483-2839

Web site: http://us.gsk.com//

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Ligand Earns $1 Million Milestone Payment as GlaxoSmithKline Submits New Drug Application for Promacta (eltrombopag) - December 21, 2007

GlaxoSmithKline Files for FDA Approval of Promacta (eltrombopag) to be the First Oral Platelet Growth Factor for Rare Blood Disorder - December 20, 2007