XENOVA, the British biotechnology firm, is looking to develop cures for heroin and Ecstasy addiction after the company said that it was “encouraged” at initial results of a new vaccine for cocaine addiction.

David Oxlade, the chief executive, citing the results of a phase two study of its anticocaine vaccine, said: “We are obviously going to look into whether the treatment can be exploited in other small molecule drugs, such as heroin and amphetamines.”

The vaccine, code-named TA-CD, is designed to prevent cocaine addicts from getting a “high” from the drug. It is believed to be the only product of its type in clinical trials, marking a novel approach to treating cocaine addicts, who usually have to rely on counselling and rehabilitation clinics.

The study showed that 58per cent of patients had been cocaine-free during the 12-week sample period, while 42 per cent had stayed off the drug after six months. Among those who relapsed, 88 per cent in one study and 63 per cent in another reported that they were less stimulated by the effects of cocaine.

The results pushed Xenova shares 6 per cent higher to 9¼p, giving the biotech minnow a market capitalisation of nearly £39 million.

Cocaine, like heroin or nicotine, is a very small molecule which, when in the bloodstream, is able to sidestep the brain’s protective layer, called the blood-brain barrier. Once inside the brain, cocaine interferes with the junctions between nerve cells, producing a high.

Xenova’s vaccine works by alerting an addict’s immune system to the presence of cocaine molecules in the blood. The vaccine stimulates the production of antibodies that bind to the cocaine molecules, making them too big to cross the blood-brain barrier.

Xenova is carrying out a large placebo-controlled trial of TA-CD, involving 130 patients, the results of which are due in 18 months. If successful, the company hopes to win rapid approval and launch the vaccine in 2007 or 2008. Mr Oxlade said that the cocaine addiction treatment market was huge, with sales potentially running into hundreds of millions of pounds a year.

The firm’s anti-smoking vaccine, meantime, is in the phase one stage. Mr Oxlade said that Xenova would wait until it had marketed the vaccines to combat nicotine and cocaine addiction before focusing on treatments for other addictions.