Oxford BioMedica, the biotechnology company, revealed yesterday that its most important drug had failed in a key kidney cancer test.

The independent Drug Safety Monitoring Board (DSMB) ruled that more doses of Oxford Biomedica's cancer vaccination drug TroVax should not be administered to kidney cancer patients after 190 patients out of 733 in a trial died.

The treatment was being developed with Sanofi-Aventis, the French pharmaceutical giant.

Shares in Oxford BioMedica plunged 59 per cent to 7.5p.

The company has an agreement with Sanofi-Aventis, worth up to €518 million (£418 million) in milestone payments, to develop the drug for patients with colorectal and prostate cancer.

Sanofi has so far paid the British minnow €48 million for access to the drug, including an initial upfront payment of €29 million. Other payments were to come as the drug met certain targets in clinical trials, with Oxford Biomedica entitled to royalty payments if the drug made it to market.

Oxford BioMedica told The Times that it informed Sanofi of the data on Thursday, and the company had been “sympathetic” but had yet to reach an agreement on how to proceed with the drug. The current kidney cancer trial will continue, although patients will not receive any more doses of TroVax. They will be monitored to see if the drug has any effects on survival rates, as the DSMB said that there was important scientific merit in the trial.TroVax is designed to be used on patients who have already had another treatment for cancer.

It was meant to work by stimulating the body's immune response to a specific antigen found on many cancer tumours. The DSMB projected from the data submitted that TroVax would be unlikely to meet its targets.

Nick Woolf, senior vice-president of Oxford BioMedica, said: “People are writing the drug off entirely but we feel that's wrong. We believe there's still value in TroVax in other cancer types.”

Mike McDonald, chief executive of Oxford Biomedica, said: “It's most unlikely that this study alone can now be the basis for registration [of the drug with regulators]. It's a setback but it's not a knockout blow. It's still possible this product will deliver a positive outcome and a survival benefit for renal cancer patients.”

Paul Cudden, biotechnology analyst at KBC Peel Hunt, said: “The value in TroVax now rests on whether Sanofi-Aventis decides to continue with the colorectal study. We believe it is more likely to wait until full results are published, which could be from mid-2009.”

Analysts reduced their forecasts for the company. Panmure Gordon cut it to “sell” from “buy”, and slashed its price target to 6p from 55p, while Cazenove downgraded the company to “in-line” from “outperform”.

It emerged last week that Oxford BioMedica is defending a case brought by Bavarian Nordic, in the US, claiming that the system by which TroVax works infringes Bavarian Nordic's patents.

Painful results

— Renovo lost half its value on the stock market in March after announcing the failure of Juvista, its scar prevention drug, in trials to prevent scarring in breast augmentation surgery. The company announced on Thursday that it has received approval of its plans to run tests for scar prevention

— GW Pharmaceuticals, the cannabis-based drugs specialist, announced in April that Sativex, one of its cannabis-based drugs, failed to meet trial expectations in treating central neuropathic pain

— AstraZeneca, the drugs giant, had four drugs fail in late-stage trials within a year in 2006-07, including Exanta, a blood-clotting medicine; Galida, a diabetes drug; Cerovive, an anti-stroke drug; and AGI-1067, an experimental drug for heart disease

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