Maisonneuve-Rosemont Hospital Université de Montréal

Selection of the type of transplant and the source of stem cells

A new protocol for selecting the type of transplant

In the case of an allogeneic transplant, stem cells may come from the bone marrow (extracted from the marrow itself) or the blood (collected from peripheral blood). It has recently been determined, however, that the source of the transplant might have an effect on patient recovery following the transplant and on the risk of relapse.

Researchers have in fact noticed that the risk of developing a chronic graft-versus-host reaction (GVH) seems to be higher when the transplant is made up of stem cells from peripheral blood, while the risk is lower when stem cells from bone marrow are used.

GVH is a post-transplant complication that can have a major impact on a patient’s quality of life and survival. Although sometimes harmful when it is severe, the graft-versus-host reaction is also closely connected to a beneficial aspect of a transplant: the graft-versus-leukemia reaction (GVL).

It has also been demonstrated that the risk of relapse is lower for patients who have experienced a GVH reaction in comparison with those who have not. It might then be an advantage to receive stem cells from a blood source when a blood cancer with an elevated risk of relapse is involved. On the other hand, it might be more beneficial to receive bone marrow stem cells if there is only an extremely slight risk of relapse for a patient, or for whom developing a GVH reaction holds no advantage.

A cross-Canada study is now under way in order to determine what type of stem cell transplant is preferable on the basis of the particular disease and patient risk factors. The study is comparing the effectiveness of bone marrow stem cells with those from peripheral blood, and evaluating both types in terms of how quickly they generate blood cells, induce a graft-versus-host reaction and maintain control of tumour growth.

The MRH team of transplant physicians are taking part in this major clinical research protocol.