Researchers in Cambridge to launch three-year £1m trial to desensitise sufferers of allergy that affects 4% of schoolchildren

Doctors are launching a major clinical trial in the search for a long-term treatment for peanut allergy after children suffering from the condition were treated successfully for the first time.

Researchers at Addenbrookes hospital in Cambridge will begin the £1m government-funded immunotherapy trial next month after a pilot study showed children who had a severe reaction to peanuts could be desensitised.

The therapy is the most promising development yet in the search for a long-term treatment for the allergy, which affects 4% of British schoolchildren.

Children who suffer a reaction to peanuts can experience a constriction of the airways, breathing trouble, asthma, itching and swelling. Unlike some other childhood allergies, peanut sensitivity rarely recedes with time. Around one in 10 reactions is serious.

The hospital has recruited 104 children who will be randomly assigned to receive the therapy or join a control group for three years. Children receiving the therapy will be given a small amount of yoghurt with one milligram of peanut flour mixed in each day. Over time, the quantity of peanut flour will be increased to the equivalent of five peanuts a day, a process designed to desensitise their immune systems to the nuts.

In the pilot, 21 of 23 children aged seven to 17 were effectively desensitised to peanuts and were able to eat food containing the nuts without suffering any reaction. Two of the children now only take the yoghurt with peanut flour once a week to maintain their tolerance.

"This is going to be the largest trial of its kind in the world and it should give us a definitive idea of whether it works and whether it's safe," said Andrew Clark, a consultant in paediatric allergy at the hospital.

Food allergy is responsible for the majority of anaphylactic shock in children and has increased by 20% in western countries in the past 10 years.

Families involved in the pilot said the therapy changed their lives. "It's dramatic," said Clark. "Before they were checking every food label every time they ate food. They would worry it would cause a reaction or even kill them, but now they can go out and eat curries and Chinese food and they can eat everyday snacks and treats.

"For their birthday they can have chocolate cake and chocolates without any fear of reactions. Our real motivation is to try to develop this as a clinical treatment that we could spread to the rest of the country," Clark told the American Association for the Advancement of Science meeting in San Diego.

Researchers said children may need to receive the immunotherapy for two to three years, after which it may be possible for them to stop without losing their tolerance."

Clark said the therapy was at the research stage and required intensive clinical oversight to ensure it was safe. "It must not be tried at home outside the research setting," he said.

A previous trial in the 1990s, which used injections rather than consumed peanut flour, produced serious side effects.