UK scientists develop safer bone marrow transplant technique

Scientists have developed a new bone marrow transplant technique that only requires a small dose of chemotherapy and may therefore make treatment safer and less distressing for children with genetic defects in their immune system (primary immunodeficiencies or PID).

Children who require a bone marrow transplant to replace their defective immune system have to receive high doses of chemotherapy so that their own bone marrow is destroyed, making space for the healthy donor stem cells.

Some very sick children do not tolerate high doses of chemotherapy very well and there is a high mortality rate among babies under one year of age, even if they are given milder chemotherapy drugs that have been developed over the past decade.

Now, researchers at Great Ormond Street Hospital for Children (GOSH) and the University College London Institute of Child Health have developed a transplant technique that uses antibodies to recognise bone marrow so that, unlike chemotherapy drugs, it does not harm surrounding healthy tissue.

The antibodies target a molecule called CD45, which is only found on blood and bone cells.

Because of this, the antibodies only target areas with bone marrow, allowing space to be made for the new donor bone marrow without damaging other tissues in the body.

The technique is detailed in the Lancet medical journal and has been trialled on 16 children with PID, 13 of whom have been cured of their underlying disease.

In addition, patients recovered twice as quickly as those who are given standard treatment and the new technique does not appear to cause long-term damage to organs.

Chemotherapy can cause a number of unpleasant side-effects, including hair loss, sickness, organ damage, infertility and growth problems.

Lead researcher Dr Persis Amrolia, a consultant in bone marrow transplants at GOSH, revealed: “Because this technique gives us an alternative to intensive chemotherapy, the treatment we can offer is safer and provides a greater chance of allowing these children to grow up to lead normal healthy lives.

“We didn’t see any of the hair loss and sickness normally associated with intensive chemotherapy for bone marrow transplant, there was much less damage to the liver, lungs and gut and we anticipate none of the harmful long-term side effects. This represents a major breakthrough in how we treat patients who have PID.”

Dr Amrolia noted that the treatment was only trialled on the sickest children who would not have been able to tolerate chemotherapy.

“Given how sick these children were before transplant, the results are remarkable,” she pointed out.

“There’s still a lot to do and the challenge now is to develop similar targeted approaches for children with other genetic diseases and leukaemia.”

Dr Kat Arney, science information officer at Cancer Research UK, said: “This is a very small study, and we don’t yet know if the new treatment will be suitable for children with cancer, but it’s a promising step in the right direction.”