Paediatrics: Stem cell transplant

Stem cell transplant

High dose therapy

This involves the delivery of myeloablative doses of chemotherapy and/or radiotherapy, followed by rescue with haemopoietic stem cells. The latter may be autologous (from patient) or allogeneic (from sibling, unrelated donor, or haplo-identical from parent). Indications for use in treatment of childhood malignancy:

·  Selected high-risk leukaemia and relapsed ALL (from allogeneic donor).

·  High risk solid tumours, including metastatic neuroblastoma, and high risk ES (autologous).

Stem cells are harvested from bone marrow or peripheral blood by leu-copheresis following ‘mobilization’ with granulocyte colony stimulating factor (G-CSF).

Conventional BMT is used for allografts. Peripheral blood stem cell transplants (PBSCT) are favoured for autografts. This offers advantages including less risk of tumour contamination, more rapid engraftment, less severe infections, avoidance of anaesthetic. Conditioning for BMT involves myeloablative radiotherapy or chemotherapy. The aim is to achieve a state of complete remission prior to conditioning. Monoclonal antibod-ies are used to suppress immune function of donor T-lymphocytes against recipient.

Outcome

Allografts carry greater risk, with approximately 10% procedure-related mortality. Morbidity and mortality from stem cell transplant are due to:

·  graft failure;

·  infection s to profound immune suppression;

·  mucositis;

·  veno-occlusive disease of the liver.

·  multi-organ failure related to the conditioning regimen.

Graft vs host disease (GVHD)

GVHD is a particular risk. It may affect any organ system but commonly skin, liver and the gastro-intestinal system. Ciclosporin A or tacrolimus are given as prophylaxis and steroids, monoclonal antibodies and other immunosuppressants may be employed in treatment.