GSK orphan drug gets full FDA approval to treat rare blood disorder

A GlaxoSmithKline orphan drug developed to treat a rare blood disorder characterized by a low number of platelets in the blood now has full U.S. Food and Drug Administration approval.

GlaxoSmithKline has full approval on a drug that can boost platelet counts in patients who bleed and bruise easily due to a rare blood disorder.

GSK (NYSE:GSK) drug Promacta has been developed to treat chronic idiopathic thrombocytopenic purpura, or ITP. Patients who have the disease often have visible bruising as well as nose bleeds because the decreased number of platelets affects the blood’s ability to clot normally.

Promacta was discovered through a research collaboration between London-based GSK, which has its U.S. headquarters in Research Triangle Park, North Carolina, and San Diego-based Ligand Pharmaceuticals (NASDAQ:LGND). The drug was developed by GSK. Clinical research on Promacta has shown that it stimulates development of the bone marrow cells that give rise to blood platelets.

The U.S. Food and Drug Administration granted Promacta orphan drug designation in May 2008, which gives a product temporary market exclusivity to encourage companies to develop treatments for rare conditions. An estimated 60,000 patients have been diagnosed with chronic ITP in the United States.

Promacta received accelerated approval in November 2008 for chronic ITP. The FDA’s accelerated approval program is a path toward marketing approval for drugs that address unmet medical needs. Full approval on Promacta required additional post-marketing clinical trials to verify the drug’s clinical benefit. Promacta does carry a black box warning that in rare cases, the drug can cause serious or even fatal liver damage.