US regulators have further extended the reach of Ligand/Novartis’ Promacta, allowing its use to treat low blood platelet count in children - aged one year and older - with the rare blood disorder chronic immune thrombocytopenic purpura.

Physicians can now prescribe the drug in paediatric patients when they have not achieved an appropriate response using other ITP medicines - such as corticosteroids or immunoglobulins - or surgery to remove the spleen.

ITP affects around five in 100,000 children each year, 30%-36% of which diagnosed with chronic forms of the condition and thus are at constant risk of significant bleeding.

Promacta’s (eltrombopag) clearance for paediatric patients was assessed in two double-blind, placebo-controlled trials, which showed that of those taking the drug, 62% had an improvement in platelet counts without rescue therapy between weeks one and six, versus 32% in the placebo group. 

The most common side effects in the treatment arm were infections of the upper respiratory tract or nose and throat, diarrhoea, abdominal pain, rash and increase in liver enzymes, the FDA said.

Promacta was first approved in the US for adults in 2008, and then subsequently for children aged six and above in June this year. It holds orphan drug status.