The mini-transplant, or transplant-lite as it is sometimes called, is a form of allogeneic transplant, although, researchers are also evaluating autologous mini-transplants. The mini-transplant uses cells from a matched donor who may be related or unrelated to the patient. In this procedure, the patient's bone marrow is not totally wiped out in preparation for the transplant. Instead, the patient is given just enough chemotherapy to allow the donor's bone marrow or stem cells to engraft in the patient. If all goes as planned the T-cells from the donor will then recognize the patient's leukemic cells as foreign, and they will mount a response against the leukemic cells. This is called the graft-versus-leukemia effect.

In a standard allogeneic transplant, the patient is given high-dose chemotherapy or radiotherapy or a combination of the two. The goal of this preparative regimen is to eliminate the leukemic cells and to suppress the immune system sufficiently to allow engraftment.

The risks in a mini-transplant are certainly less than in a standard allogeneic transplant; however, the risk of developing chronic graft-versus-host disease is still very significant. For this reason, the mini-transplant is certainly not a minor undertaking as its name might suggest. Indeed, it should be viewed as potentially having the same frequency of long-term complications as a standard allogeneic transplant.