US biotechnology giant Amgen has reportedly been served with a subpoena for information regarding its anti-inflammatory blockbuster Enbrel, following accusations that the firm promoted the drug for unlicensed uses.

Documents going back as far as 2002 relating to the marketing and sale of Enbrel (etanercept) have been requested, and a spokeswoman for Amgen told Reuters that the company will “cooperate fully with the New Jersey attorney general in this investigation.”

There were also allegations by two of the company’s sales representatives that they had been pushed by the firm into getting hold of patient data to sift out those suffering from psoriasis who could be suited to treatment with the drug, thereby violating patient confidentiality laws, reports the New York Times.

The news came shortly after Amgen and Wyeth reported results from a Phase III study showing that Enbrel was able to significantly improve the symptoms of moderate-to-severe plaque psoriasis in children and adolescents.

The results, which will be published in the New England Journal of Medicine, will support the company’s application to market the drug in paediatric psoriasis. If successful, Enbrel could be the first biologic and systemic therapy specifically approved for use in this age group, the company said.

Enbrel is a fully-human soluble tumour necrosis factor receptor, first approved in 1998 for moderate-to-severe rheumatoid arthritis and since used in nearly 500,000 patients around the globe. The drug generated sales of $821 million in the third quarter of 2007, marking growth of 16% over the year-earlier period.