Microtransplantation to Treat Refractory or Relapsed Hematologic Malignancies in Younger Patients

Allogeneic transplant can sometimes be an effective treatment for leukemia. In a traditional allogeneic transplant, patients receive very high doses of chemotherapy and/or radiation therapy, followed by an infusion of their donor's bone marrow or blood stem cells. The high-dose chemotherapy drugs and radiation are given to remove the leukemia cells in the body. The infusion of the donor's bone marrow or blood stem cells is given to replace the diseased bone marrow destroyed by the chemotherapy and/or radiation therapy. However, there are risks associated with allogeneic transplant. Many people have life-threatening or even fatal complications, like severe infections and a condition called graft-versus-host disease, which is caused when cells from the donor attack the normal tissue of the transplant patient. Recently, several hospitals around the world have been using a different type of allogeneic transplant called a microtransplant. In this type of transplant, the donor is usually a family member who is not an exact match. In a microtransplant, leukemia patients get lower doses of chemotherapy than are used in traditional allogeneic transplants. The chemotherapy is followed by an infusion of their donor's peripheral blood stem cells. The objective of the microtransplant is to suppress the bone marrow by giving just enough chemotherapy to allow the donor cells to temporarily engraft (implant), but only at very low levels. The hope is that the donor cells will cause the body to mount an immunologic attack against the leukemia, generating a response called the "graft-versus-leukemia" effect or "graft-versus-cancer" effect, without causing the potentially serious complication of graft-versus-host disease. With this research study, the investigators hope to find out whether or not microtransplantation will be a safe and effective treatment for children, adolescents and young adults with relapsed or refractory hematologic malignancies