Amgen drug stimulates platelet production in test

Immune thrombocytopenic purpura (ITP) is characterized by an immune system malfunction that recognizes the body’s own platelets as foreign and destroys them, potentially resulting in dangerously low platelet counts of less than 30,000 platelets per micro-liter.

Interim results for the 34 patients treated with AMG 531 for up to 48 weeks showed that overall 85% of patients in the study achieved a platelet response, defined as doubling of the baseline platelet count and at least 50,000 platelets per micro-liter of blood. The data were presented at the American Society of Hematology.

Platelets are specialized blood cells that help prevent and stop bleeding by participating in clotting. Normal platelet range for a person without ITP is 150,000 to 400,000 platelets per microliter. AMG 531 is being investigated as a new approach to treat ITP, and other platelet deficiencies, by directly increasing platelet production to outpace platelet destruction by the immune system.

“Traditional therapies for ITP have focused on diminishing platelet destruction by suppressing the immune system, beginning with the use of steroids, followed by surgical removal of the spleen and more intensive immunosuppression. These treatments have potentially serious side effects. For ITP patients who do not respond to these therapies, there are no effective treatment options,” said Dr James George, professor of medicine at the University of Oklahoma health sciences center, Oklahoma City.