Eltrombopag, GSK’s new thrombocytopenia treatment, has performed
exceptionally well in a six-week Phase II trial of patients with the
autoimmune disease, chronic idiopathic thrombocytopenia purpura,
according to lead investigator Dr James Bussell of New York’s Presbyterian
Hospital’s Weill Cornell Medical Center.
Data presented at the American Society of Hematology meeting in Orlando
showed the study had already reached its primary endpoint by the time only a third of the planned 270 patients had been treated.
Dr Bussell told an ASH press conference: “The trial was stopped at the
interim analysis of the first 90 patients because results were significant
at the 0.001 level for both the 50mg and 75mg doses.” More than 70% of
patients achieved a platelet count greater than 50,000 with a 50mg dose
while this rose to 80% with a 75mg dose, he said. “At both these
doses there was a dramatic decrease in bleeding in line with platelet
increases.” The incidence of side effects were similar to those seen with
Eltrombopag, to be called Promacta in the USA, is the first orally
administered, once-daily treatment for thrombocytopenia and is set to be a
“major advance in the management of ITP,” said Dr Bussell. It is thought
to work by stimulating thrombopoietin receptors on megakaryocytes in the
bone marrow to increase production of platelets. Previous therapies have
focused on inhibiting destruction of platelets by suppressing the immune
system or surgically removing the spleen.
Six-month Phase III trial has already begun
GSK announced last week that the product has started a six-month Phase III study and, although ITP is a fairly rare condition affecting around one
person in 10,000, thrombocytopenia also occurs in 5%-10% of all patients
admitted to hospital as a consequence of chemotherapy and secondary
hepatitis C infection.
The company says it expects to submit data in at least one indication to
the US and European regulatory authorities in 2007-8.
By Olwen Glynn Owen