Antisoma hit by Roche decision to return cancer drug rights

Shares in UK biotech firm, Antisoma, took a hit after its partner, Roche, returned the rights to two of its most promising experimental cancer drugs, despite them both reporting recent positive clinical trial data.

Antisoma, which specialises in the development of cancer treatments, said it would retain the rights for R1550, a breast cancer drug currently in phase I trials, and AS1404, a drug in phase II for ovarian and non-small cell lung cancer.

Both drugs were part of a $500m R&D partnership deal that the two firms signed in 2002, which saw Roche take a 5 per cent stake in the British firm.

Antisoma remained upbeat about its chances of successfully bringing the drugs to market. In a statement, CEO Glyn Edwards said: ìThis is a great moment for AntisomaÖ We are excited by the potential of AS1404 to bring benefits to patients with a variety of cancers and look forward to seeing further data from trials in lung cancer and other tumour types.î

Antisoma also said it was looking to move R1550 (which will be re-designated AS1402) into early phase II trials after initial tests on breast cancer patients showed it was ìwell toleratedî at maximum doses.

ìWe and Roche both feel that Antisoma is best placed to investigate [the drug's potential] further and that a phase IIa in pre-surgical breast cancer is the logical next step,î said Edwards.

Despite the encouraging data for both compounds, analysts said Roche's reversal and the consequent lack of validation from the world's leading oncology company had cast a shadow over Antisoma's risk profile.

A Roche spokesman hinted that the relatively short molecule patent life of AS1404 was partly behind its decision to return the rights to Antisoma.

The move means Antisoma will miss out on an estimated milestone payment of $15m (?8m).

Roche went some way to allaying investors' fears by declaring that it remained ìabsolutely committedî to the 2002 collaboration, which encompassed ten drugs in total, and would continue to examine new drugs developed by Antisoma.