Donor-derived CD19-targeted T cells in allogeneic transplants

Purpose of review Allogeneic hematopoietic stem cell transplantation (HSCT) is still partially ineffective in curing high-risk hematological malignancies, with estimates of relapse rates ranging from 40 to 50%. The purpose of this review is to discuss the emerging therapeutic options for patients with relapsed disease following HSCT based on adoptive immunotherapy using donor-derived T cells genetically engineered to express CD19- specific chimeric antigen receptors (CARs). Recent findings Adoptive cell therapy (ACT) with CAR-modified T cells represents an attractive therapeutic option for further enhancing the graft-versus-leukemia effect. However, CAR-modified T cells are often obtained using apheresis products collected from the patient's own blood, a procedure that has hindered the application of CAR-based therapies into the clinic. Alternative approaches rely on CAR T cells derived from donors rather than the patient's own blood. Therefore, it appears that overcoming the practical limitation of allogeneic T cell-induced graft versus-host-disease is a key to providing access to CAR immunotherapy to all eligible patients. Summary Donor-derived CD19-CAR T cells may advance the field of CAR immunotherapy by controlling relapse in leukemic patients and improving the range of applications of ACT protocols.