The mini-transplant, or transplant-lite as it is sometimes called, is a form of allogeneic transplant. Although it is commonly called a mini-transplant, the term used by physicians is, non-myeloablative transplant: myelo is a Greek word meaning marrow and ablate means to destroy. Thus, a non-myeloablative transplant is one that does not completely destroy the patient's diseased marrow. Because this procedure is relatively new--mid 1990's--it's risks and benefits have not yet been clearly established.

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 totally destroy the patient's bone marrow in an attempt to eliminate all leukemic cells and to suppress the patient's immune system sufficiently to allow engraftment.

In a mini-transplant, however, 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.

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.