Irradiated CD19 chimeric antigen receptor YTS cells retain antitumor activity and offer a scalable alternative to autologous CAR-T therapy.

Chimeric antigen receptor (CAR) T cell therapies have revolutionized treatment of hematologic malignancies such as lymphoma and multiple myeloma. However, their success is limited by high manufacturing costs, reliance on autologous T cells, variable product quality, and life-threatening toxicities like cytokine release syndrome. In contrast, natural killer (NK) cells offer a safer, more flexible alternative, but their clinical translation remains constrained by complex expansion protocols and high production costs. Here, we present a transformative approach using the human NK cell line YTS, which is amenable to large-scale culture, genetic manipulation, and cryopreservation. By introducing a CD19-specific CAR into YTS cells, we generate potent effector cells capable of selectively eliminating CD19-expressing targets. We demonstrate that CAR signaling in YTS cells requires intracellular activation and, in certain tumor settings, is enhanced by co-stimulation via the 2B4-CD48 pathway. Importantly, irradiation of YTS-CAR cells prevents proliferation without compromising their cytotoxic function even after freezing and thawing. In preclinical models, injections of irradiated YTS-CAR cells significantly reduced CD19+ tumor burden, underscoring their therapeutic promise. This work positions engineered YTS cells as a novel, scalable, and cost-effective "off-the-shelf" immunotherapy platform suitable for treating refractory leukemias and lymphomas. Future studies will be required to assess safety and to explore applicability to autoimmune diseases and solid tumors.