FDA approves GSK’s platelet-boosting drug Promacta

Philadelphia, November 21: The U.S. Food and Drug Administration on Thursday granted accelerated approval to a new platelet-boosting drug, Promacta, for treating chronic immune thrombocytopenic purpura (ITP) disorder in adults.

Manufactured by British drugmaker GlaxoSmithKline Plc, the drug is the first oral thrombopoietin (TPO) receptor agonist approved to treat bleeding problems caused by a rare immune systemdefine disorder.

Chronic ITP is a disorder marked by low platelet count (thrombocytopenia) in the blood. As the blood platelets induce blood clotting, a very low platelet count leads to bleeding diathesis (the unusual susceptibility to bleed) and purpura (appearance of red or purple discolorations on the skin). The bleeding severity ranges from mild to lethal. An estimated 60,000 individuals are diagnosed with chronic ITP in the United States.

The drug, Promacta, is an oral, non-peptide thrombopoietin receptor agonist that helps stimulate the proliferation and differentiation of megakaryocytes, the bone marrow cells that induce blood platelets.

The approval is based on the results of the clinical trial that involved 114 adult patients with chronic ITP and baseline platelet counts of less than 30,000/microliter. While 76 patients were randomly assigned to receive a 50mg once-daily dose of Promacta (eltrombopag olamine) for six weeks, 38 were put on a placebo pill. However, the Promacta dose could be increased to 75mg in patients not responding to initial three weeks of treatment.

Results of the study revealed that Promacta when administered at a 50-75mg once-daily dose was significantly effective in increasing the platelet count. It also helped reduce the bleeding in adult patients with chronic idiopathic thrombocytopenic purpura (ITP).

However, as the drug may cause hepatotoxicity (chemical-driven liver damage) patients on active Promacta therapy must undergo regular serum liver tests.

GSK now intends to submit a Marketing Authorization Application (MAA) seeking approval for marketing the drug in Europe, where it will be sold under proposed trade name Revolade.