GlaxoSmithKline plc (LSE and
NYSE: GSK) announced results from an international, pivotal Phase III study
of its investigational non-peptide oral platelet growth factor, PROMACTA(R)
(eltrombopag olamine). Data from this study showed that PROMACTA at 50-75mg
once daily resulted in a statistically significant increase in platelet
counts and also reduced bleeding in adult patients with chronic idiopathic
thrombocytopenic purpura (ITP). These patients had previously received and
failed current standard ITP treatments. These data, which are part of a
six-week study of PROMACTA in patients with chronic ITP, were presented at
the 12th congress of the European Hematology Association (EHA) in Vienna,
Austria.(1)

“ITP is a condition that can be serious for some individuals, or those
who fail to respond to therapy and not only puts patients at risk of
bleeding, but may also cause severe fatigue, bruises and complications
during surgery or pregnancy,” says Drew Provan, M.D., Senior Lecturer in
Hematology, Department of Hematology, Royal London Hospital, U.K. and
investigator for this trial. “Options are particularly limited for those
patients who fail to respond to primary treatment altogether and those who
initially respond and then fail. These trial results demonstrate that
PROMACTA may represent the potential for a new oral therapy to reduce the
number of bleeding episodes in ITP patients.”

There are estimated to be between 50,000-100,000 individuals diagnosed
with chronic ITP in the U.S. In Europe, primary ITP is estimated to affect
50 to 100 new persons per million per year.(2) People with ITP often bleed
from small blood vessels causing bruises, nosebleeds, bleeding from the
gums during dental work or other bleeding that is difficult to stop. The
predicted five- year mortality rates for ITP patients with persistent low
platelet counts range from 2.2% for patients younger than 40 years of age,
to 47.8% for those older than 60 years.(3)

“We are extremely encouraged by these PROMACTA results, and what this
may mean for ITP patients,” said Paolo Paoletti, M.D., Senior Vice
President, Oncology Medicine Development Center, GSK. “This pivotal Phase
III trial data and our ongoing efforts to assess the benefits of both
short- and long-term treatment of PROMACTA will be part of GSK’s commitment
to work with regulatory authorities and ensure new treatment options for
ITP patients are provided.”

The Phase III trial was an international, randomized, double-blind,
placebo-controlled study that enrolled 114 adults with chronic ITP and
baseline platelet counts of

At the end of the trial, 59% of PROMACTA treated patients and 16% of
placebo treated patients achieved a platelet count of more than
50,000/microliter. Importantly, there was a significantly lower incidence
of bleeding events during treatment with PROMACTA compared to placebo
(p=0.029) with clinically significant bleeding (WHO Grades 2-4) observed in
fewer PROMACTA patients (16%) than placebo patients (36%). The most common
adverse event (AE) observed in this study was headache, reported in 8% and
11% of patients receiving PROMACTA and placebo respectively. Other AEs
included nausea, nasopharyngitis, diarrhea and vomiting.

About PROMACTA

PROMACTA (eltrombopag olamine) 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,
and thus can be considered a platelet growth factor.(4) The safety profile
will be further examined in ongoing clinical trials. PROMACTA was
discovered as a result of research collaboration between GlaxoSmithKline
and Ligand Pharmaceuticals. It is being developed by GlaxoSmithKline.
PROMACTA is an investigational compound that has not received regulatory
approval in any market for any indication at this time.

Ongoing Trials

Several PROMACTA trials investigating the short- and long-term
treatment of chronic ITP are currently open and enrolling.(5) EXTEND
(Eltrombopag eXTENded Dosing Study) is an open-label study for patients who
had participated in previous PROMACTA trials and wished to take PROMACTA
for the long-term treatment of their chronic ITP. RAISE (RAndomized placebo
controlled ITP Study with Eltrombopag) is a global, randomized,
double-blind, placebo-controlled Phase III trial currently assessing the
safety, efficacy and tolerability of PROMACTA in a long-term treatment
setting (up to six months) involving 189 patients across 135 centers in 26
countries. REPEAT (Repeat ExPosure to Eltrombopag in Adults with Idiopathic
Thrombocytopenic Purpura) will involve 50 patients with chronic ITP and
will assess the safety and efficacy of repeated administration of PROMACTA.
For further information on the trials, visit itpstudy or
clinicaltrials.

About Idiopathic Thrombocytopenic Purpura

ITP is characterized by increased autoimmune platelet destruction
and/or inadequate platelet production. Its cause is currently unknown. Some
patients with ITP are asymptomatic or have mild bruising while others
develop more serious bleeding that can be life-threatening.(6) A normal
blood platelet count is greater than or equal to 150,000/microliter and
less than or equal to 400,000/microliter.(7) A reduction in platelet count
(to a level