This new therapy is fantastic because it gives the patient's immune system the boost it needs

Dr Sue Beath

He had a particularly severe form of the condition, in which the nerves controlloing the intestine do not form properly.

His only chance of survival was a combined liver and small bowel transplant and the surgery was a success.

But the drugs he was given to prevent the organs being rejected suppressed his immune system and he developed post-transplant lymphoproliferative disease (PTLD).

In an effort to save his life, doctors at Birmingham Children's Hospital decided to make him the first child in the world to receive cytotoxic T cell therapy.

Boosting immunity

The therapy uses specially selected blood cells to boost the body's natural immune system and fight off the disease.

Dr Sue Beath, who treated Mohammed, said: "With a cancer like Mohammed's we faced an impossible decision - if we'd continued to administer the drugs then the cancer would have grown and spread, but if we'd stopped the drugs then his new organs would have been rejected.

"This new therapy is fantastic because it gives the patient's immune system the boost it needs to effectively target and kill off the cancer without endangering the transplanted organs."

Scientists believe that Mohammed's cancer is caused by the Epstein-Barr virus, which is better known for causing glandular fever.

In healthy people the virus can cause illness but is rarely dangerous.

However, in transplant patients with a weakened immune system it can lead to cancer.

The new treatment - pioneered by the Cancer Research Campaign - uses blood from healthy donors who have an immune response to the virus and whose tissue type is carefully matched to the patient.

It was pioneered by scientists from the University of Edinburgh who developed a way of extracting a particular type of white blood cell - called killer T cells - which form a vital part of a healthy immune system.

Crucial cells

It's great news that we may now have a therapy that can give these children new hope

Dr John Toy

Professor Dorothy Crawford, who headed the research team, said: "Killer T cells are especially important in fighting viruses and cancer because they patrol the body and attack cells which have been infected or have turned cancerous.

"In healthy people, cancers probably begin to develop fairly regularly but the immune system kills them off.

"In transplant patients, the immune system is muted and these killer T cells are few and far between. But by giving Mohammed a dose of cells similar to his own we have helped him defeat the cancer."

Mohammed's mother said: "The whole family is now looking forward to enjoying the holiday season together and this is the most precious gift we could hope for."

Dr John Toy, medical director of the Imperial Cancer Research Fund, said: "Thankfully, childhood cancer is still very rare, but we know that children whose immune systems are suppressed following transplants can be very susceptible to the disease.

"It's great news that we may now have a therapy that can give these children new hope."

Disease

Hirchsprungs Disease is a rare condition in which the nerves controlling the intestine do not form properly.

In mild cases this just affects the lower bowel and patients improve after surgery to remove the affected part.

In serious cases like Mohammed's the whole of the intestine is affected and conventional surgery does not cure the problem.

The severely affected patients cannot eat or drink and depend on intravenous feeding.

Birmingham Children's Hospital is the only centre in the UK designated for intestinal transplantation in children.