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