Shares in UK drugmaker Antisoma were on the rise this morning after the company announced that sanofi-aventis US has bought the US rights to its leukaemia drug oral fludarabine for $65 million.

The US rights to oral fludarabine, a tablet formulation of fludarabine phosphate, widely used to treat chronic lymphocytic leukaemia, were acquired by Antisoma through its purchase of Xanthus Pharmaceuticals in June 2008 last year, which had originally bought the rights from Bayer Schering Pharma.

But Antisoma decided to sell off its rights to the drug in order to free up resources to fuel progress in its priority development programmes. According to Glyn Edwards, the UK group’s chief executive, the sale will roughly double its cash resources, and so provides the means to fund development of key candidates until at least mid 2011, “which is well beyond when we expect key Phase III results for our leading products, ASA404 and AS1413.”

ASA404 is currently in Phase III trials for lung cancer, while AS1413 is in late-stage testing for secondary acute myeloid leukaemia. Antisoma is certainly pinning much hope on the success of these drugs, which, it believes, both have significant sales potential and could help the firm achieve its primary aim of “becoming a sustainable business based on recurring income from product sales”.

Under the terms of the deal, sanofi-aventis is now liable to pay Bayer Schering Pharma royalties on sales of the drug in the US.