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Promacta boosts platelets in patients with immune thrombocytopenic purpura


Patients suffering from a blood disorder that prevents proper clotting have the option of a new medication that may dramatically improve their health. There are estimated to be between 50,000 and 100,000 individuals in the United States diagnosed with chronic immune thrombocytopenic purpura ( ITP ), an autoimmune disease that dramatically reduces the number of platelets in their blood, causing bruises, nosebleeds and, rarely, life-threatening brain hemorrhages.

Promacta ( Eltrombopag ) was granted accelerated approval by the FDA ( Food and Drug Administration ) in November 2008 for the treatment of thrombocytopenia in patients with chronic immune ( idiopathic ) thrombocytopenic purpura who have had an insufficient response to corticosteroids, immunoglobulins or splenectomy. Promising results of an international, multicenter Phase III clinical trial, led by NewYork-Presbyterian/Weill Cornell Researchers, were the basis of this approval and are published in the Lancet.

The study follows a previous Phase II study published late 2007 in the New England Journal of Medicine. This trial showed that Eltrombopag was effective in raising platelet counts and lowering bleeding in adult subjects with chronic immune thrombocytopenic purpura. The Phase II study's results also determined the most promising dose of 50 mg, which was given to all of the experimental subjects in the Phase III study.

The Phase III study tested 114 subjects, who were all 18 years and older, with at least six months of history with immune thrombocytopenic purpura and with low-platelet counts of 30,000 per microliter ( microL ) of blood ( normal range is 150,000 to 400,000 ). The subjects were split into two groups: two-thirds were in an experimental group that received the standard of care with the addition of 50 mg of Eltrombopag, and a control group received the standard of care and placebo.

By the end of the 43-day testing period, 59 percent of subjects receiving Eltrombopag achieved platelet counts at or over 50,000 per microL of blood, compared with 16 percent of subjects in the placebo group. A safe-level platelet count is between 30,000 and 50,000 per microL of blood.
Eltrombopag subjects were almost 10 times more likely to reach the target platelet counts as the placebo group.

Currently, patients are treated with corticosteroids, such as Prednisone, which may have side effects such as fatigue, mood swings and weight gain. Other common treatments include IV anti-D and IV gammaglobulin, and also Rituximab. More drastic measures, like surgical removal of the spleen ( splenectomy ) are sometimes taken in order to prevent the body from destroying platelet cells within the organ. However, this may put a patient at risk for blood stream infections because of the spleen's role as a filtering organ of the immune system.

Eltrombopag works by stimulating the production of cells in bone marrow that form platelet cells in the blood. Past studies have shown that the drug boosts platelet counts in both ITP and normal subjects.

Immune thrombocytopenic purpura is an autoimmune disease in which anti-platelet antibodies accelerate destruction of platelets. ITP patients commonly have platelet counts of less than 30,000 per cubic millimeter, compared to normal platelet counts of between 150,000 and 440,000.
Immune thrombocytopenic purpura affects women of childbearing age at two to three times the rate of men and has an increased incidence in the elderly.

Source: New York- Presbyterian Hospital / Weill Cornell Medical Center/Weill Cornell Medical College, 2009

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