Therapeutic Potential of CAR-CIK Cells in Acute Leukemia Relapsed Post Allogeneic Stem Cell Transplantation

Adoptive cellular therapy with donor-derived T cells has always been an attractive strategy after allogeneic hematopoietic stem cell transplantation (allo-HSCT) to reduce the risk of relapse in acute myeloid and lymphoid leukemias. Donor lymphocyte infusion (DLI) is still the best-established option, especially in the preemptive phase when measurable residual disease (MRD) becomes positive and in the prophylactic setting-when MRD is not detectable. However, the clinical benefit of DLI is counterbalanced by the possible onset of graft-versus-host disease (GvHD), which continues to restrict its wide application. To address this challenge, several alternative cell-based strategies have been developed. One of these is represented by cytokine-induced killer (CIK) cells, generated from donor peripheral blood mononuclear cells through stimulation with anti-CD3 antibodies, interferon-γ, and interleukin-2. These cells are characterized by a hybrid phenotype, combining T-cell functions with natural killer-like properties, and exhibit antitumor activity in an MHC-unrestricted manner. CIK cells are generally well tolerated and associated with low toxicity but their efficacy is so far modest. Based on the experience of CAR-T in the treatment of B-cell lymphoid disease, CIK cells have been engineered with chimeric antigen receptors (CAR) developing the CARCIK cells. This novel cellular strategy represents a promising approach in the treatment of acute myeloid and lymphoid leukemia relapsed post-allo-HSCT. This review provides an overview of the current CAR-CIK experiences in the setting of acute leukemias and outlines future directions for their clinical translation.