(Reuters) - GlaxoSmithKline Plc said U.S. health regulators had approved its drug Promacta for the additional use of treating low platelet count in hepatitis C patients that will allow them to undergo a standard therapy for the liver disease.
The drug, already approved as a treatment for idiopathic thrombocytopenic purpura — low platelet count of unknown cause — was developed along with Ligand Pharmaceuticals Inc.
Ligand shares rose as much as 17 percent in heavy volumes by mid-day on the Nasdaq.
"We believe that Promacta sales are set to see an uptick with approval in a significant population with unmet medical need," Roth Capital analyst Joseph Pantginis said in a note.
About 3.2 million people in the United States have chronic hepatitis C, the most common blood-borne virus, according to the U.S. Centers for Disease Control and Prevention.
Pantginis estimated Promacta sales of $328 million in 2013, corresponding to $24.6 million in revenue for Ligand.
"We maintain our belief that Glaxo is committed to growing the Promacta franchise with approval in additional indications with about 20 clinical trials ongoing," the analyst added.
The drug, also known as eltrombopag, is approved in 90 countries and is marketed under the brand name Promacta in the United States and as Revolade elsewhere.
It is now the first supportive care treatment available to patients who are ineligible or poor candidates for interferon-based hepatitis C therapy due to low platelet counts.
The U.S. Food and Drug Administration's approval was based on results from two late-stage studies that collectively enrolled 1,521 patients.
Reporting by Prateek Kumar in Bangalore; Editing by Saumyadeb Chakrabarty