Bone marrow transplant to treat childhood leukaemia

Dr Intezar Mehdi
Consultant paediatric haematologist, oncologist and BMT, HCG Cancer Hospital Bengaluru

Blood disorders and cancers, especially in children can be fatal if not managed properly. They can cause blood not to have an adequate number of cells, platelets, proteins or nutrients, which interferes with its functioning. Thalassemia, sickle cell disease and childhood leukaemia (or blood cancer) are some of the challenging and not uncommon blood-related disorders that are known to affect children. India has the third-highest number of blood cancer cases, preceded by the US and China. Leukaemia in children is a growing burden and a serious concern. It needs to be treated on time to help the patient survive and prolong life.

Childhood leukaemia is the most common type of cancer found in children and young adults where abnormal white blood cells are formed in the bone marrow. The abnormal cancer cells replace the normal red blood cells, white blood cells and platelets and cause various problems. Anaemia, bleeding risk and decreased immunity leading to increased risk of infection are some of the consequences. Leukaemia is a type of cancer that originates in the blood-forming tissue of the bone marrow or in the immune system cells.

The treatment options for childhood leukaemia depend on the diagnosis. Usually, most leukaemia cases can be managed with chemotherapy and supportive care with blood and platelets transfusion, antibiotics for managing infections. However, some high-risk or recurrent leukaemia can be cured only with innovative therapies like bone marrow transplant. The chances of survival and cure are better in certain subgroups of leukaemia.

A bone marrow transplant is required when the bone marrow ceases to function and does not produce enough healthy blood cells. Bone marrow transplant is not surgery. It is a medical procedure that requires expertise and dedicated teamwork. It is performed only in centres that have trained doctors and nurses and other support staff. It is also called stem cell transplant or hematopoietic stem cell transplant. There are two basic types of BMT, autologous and allogeneic. Autologous BMT is a procedure wherein the patient’s own stem cells are given after high dose chemotherapy as a rescue. This procedure is useful in many solid tumours, especially high-risk and relapsed cases, and in lymphomas. Allogeneic BMT is a procedure wherein stem cells are given from a healthy donor. The donors must be HLA matched (done on blood tests or saliva samples to match antigens and check for compatibility. Donors could be siblings, family members, or unrelated donors from the registries. The source of stem cells could be bone marrow or peripheral blood stem cells or cord blood. Allogeneic BMT is curative in much difficult and relapsed leukaemia, and is an important curative option for thalassemia and sickle cell disease.

Initially, medicines are given called conditioning chemotherapy – which basically removes the diseased marrow and creates space for the healthy marrow/ stem cells. Then the healthy stem cells are given like a blood transfusion through an IV catheter. These cells flow into the bloodstream and find their way into the marrow. The type of transplant that is suitable for the child is determined after examining the overall health and type of blood cancer the child is suffering from. But generally, all leukaemia cases where the BMT is indicated, allogeneic BMT will be required. The type of donor and stem cells required depends on the type of leukaemia and overall health status of the child. There is no specific age group required as a majority of the time, the leukaemia that needs BMT is very aggressive and we need to do BMT as soon as it is in control. Children as young as a few months to adolescents can undergo BMT when indicated.