Improvement of monoclonal antibody therapy against cancer through engineering stem cell-derived CD16-enhanced universal NKT cells

Monoclonal antibody (mAb)-based immunotherapies have revolutionized cancer treatment, yet their efficacy remains limited in many solid and hematologic malignancies due to insufficient effector cell engagement, tumor antigen loss, and immunosuppressive tumor microenvironments. To overcome these limitations and enhance the therapeutic potential of mAb therapy, we developed an allogeneic invariant natural killer T (NKT) cell platform through hematopoietic stem cell (HSC) engineering and feeder-free in vitro differentiation. Specifically, we introduced an invariant NKT T cell receptor (TCR) and a high-affinity, non-cleavable CD16a (FcgammaRIIIa) receptor into HSCs, enabling the generation of CD16-enhanced HSC-engineered NKT ( CD16 HSC-NKT) cells. These cells can be produced at high yield and purity in a scalable, feeder-free culture system. The resulting CD16 HSC-NKT cells preserve the hallmark NKT phenotype and exhibit robust cytokine secretion, cytotoxicity, and tumor infiltration capacity. Functionally, CD16 HSC-NKT cells mediate potent antibody-dependent cellular cytotoxicity (ADCC) both in vitro and in vivo when combined with tumor-specific monoclonal antibodies, leading to synergistic tumor regression. Beyond direct cytotoxicity, CD16 HSC-NKT cells also display multi-targeted antitumor mechanisms, including recognition of CD1d-presented glycolipid antigens and engagement of stress-induced NK ligands. In preclinical tumor models, CD16 HSC-NKT cells demonstrated superior persistence and metabolic fitness compared with conventional peripheral blood-derived NKT cells. Importantly, CD16 HSC-NKT cells were found to reshape the tumor microenvironment by selectively depleting immunosuppressive tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), thereby promoting a more pro-inflammatory and immune-permissive milieu. No evidence of graft-versus-host disease, cytokine release syndrome, or long-term organ toxicity was observed, supporting a favorable safety profile. Collectively, our study establishes CD16 HSC-NKT cells as a universal, off-the-shelf cellular immunotherapy that can be flexibly paired with diverse monoclonal antibodies to enhance their efficacy, overcome resistance, and expand the therapeutic reach of antibody-based cancer treatment.