Natural killer cell-based immunotherapies for colorectal cancer: Current strategies, challenges, and future perspectives.

Natural killer (NK) cells have emerged as promising therapeutic agents for treating colorectal cancer because of their innate ability to recognize and eliminate tumor cells without prior sensitization. In this review, NK cell-based immunotherapeutic approaches, including cytokine therapy, immune checkpoint inhibition, antibody-dependent cellular cytotoxicity, and adoptive cell transfer, are comprehensively examined, and their respective clinical potential and limitations are highlighted. We discuss critical challenges in NK cell expansion, genetic engineering (particularly chimeric antigen receptor-NK development), and tumor microenvironment-mediated immunosuppression. Furthermore, we explore innovative strategies such as combination therapies, nanotechnology-enhanced delivery, and personalized medicine approaches that aim to overcome the current barriers. The review concludes with future directions emphasizing the need for standardized manufacturing protocols, new strategies to improve NK cell persistence, and clinical validation of emerging technologies, positioning NK cell immunotherapy as a transformative modality for colorectal cancer treatment.