Present Status of Stem Cell Transplant in Acute Leukemia in Children and Adults

The stem cell transplant (SCT) has long been considered a standard of care for patients who have high-risk or relapsed/refractory leukemia. The role of allogeneic (allo) SCT has recently been blurred with the development of newer and targeted agents and with the availability of CAR-T cell therapy. However, allo SCT still holds a crucial role in the treatment of leukemia. This chapter highlights the current status of allo SCT in pediatric and adult leukemia patients. The prognosis of acute lymphoblastic leukemia (ALL) is different in children compared to adults, whereas acute myeloid leukemia (AML) has a nearly similar prognosis, though prognosis worsens with aging in all leukemias as adult/elderly patients have high-risk cytogenetics and tolerate chemotherapy poorly. Though there has been advancement in the newer modalities for the treatment of leukemias, there has been simultaneous improvement in the transplant outcomes because of innovative strategies for the management of GVHD and infections. Patients with relapsed or refractory leukemia have poor survival if they do not undergo SCT. Though matched sibling donor (MSD) allo SCT is the preferred SCT, those patients who lack MSD can be offered matched unrelated donor (MUD) or haploidentical SCT. Recently, the availability of CAR-T cell therapy has challenged the requirement for allo SCT in B-cell ALL. For T-cell ALL and AML patients, CAR-T cell therapy is still in the early phase of development, and allo SCT is the only curative hope. The real benefits of allo SCT are based on two principles, the first is the replacement of mutagenic host stem cells with donor’s healthy stem cells (genetically mediated effect) and the second is the provision of graft-versus-leukemia (GVL) effect by donor’s T cells (adoptive-T cell immune-mediated effect).