Microtransplantation, an option to explore in hematological malignancies: A review article

Abstract

Abstract Hematopoietic stem cell transplant remains a valuable option for a variety of hematological malignancies, but it has its limitations given the patient’s old age, availability of donors, and the risk of morbidity and mortality associated with the procedure like graft-versus-host disease. Microtransplantation (MT) is nonengrafting allogeneic cellular therapy performed by infusing human leukocyte antigen-mismatched allogeneic peripheral blood CD34+ stem cells mobilized with granulocyte colony-stimulating factor after chemotherapy or targeted therapy. A state of transient microchimerism without engraftment will exist postinfusion, and the patient will benefit from graft-versus-tumor effect without being at high risk for graft-versus-host disease. A total of 600 patients with a diagnosis of acute myeloid leukemia, Philadelphia positive acute lymphoblastic leukemia, myelodysplastic syndrome, Hodgkin, and non-Hodgkin’s lymphomas were included in the 11 articles in this review. The results show improved overall survival and progression-free survival, which suggest MT as a valid option to be investigated further in prospective controlled studies. The improved outcomes could be explained by combined recipient-versus-tumor and graft-versus-tumor effects as the patient immune system is preserved, natural killer cells anti-leukemic effect within MT infusion and the effects of regulatory T cells. The major toxicity is myelosuppression, while nonhematologic toxicities are rare.