evaluation of the synergistic effects of photobiomodulation and natural killer cell therapy in a colorectal cancer xenograft mouse model

Background: colorectal cancer (crc) is a major cause of cancer-related mortality worldwide, highlightingthe need for more effective therapeutic approaches. this study aimed to evaluate the synergistic antitumoreffects of combining natural killer (nk) cell-based immunotherapy with photobiomodulation (pbm) in a crcxenograft model.methods: human peripheral blood-derived nk cells were isolated, and their cytotoxic activity was confirmedin vitro against ht-29 crc cells. nude mice bearing ht-29 xenografts were assigned to four groups: control,pbm (808 nm), nk therapy, and combined nk + pbm treatment. tumor size was monitored throughout thestudy, and excised tumors were analyzed histologically for nk cell infiltration, mitotic index, and apoptosis.results: both nk therapy and pbm alone significantly reduced tumor growth compared to the control. thecombined nk + pbm group demonstrated the greatest suppression of tumor progression. histopathologicalanalysis revealed markedly enhanced nk cell infiltration, decreased mitotic activity, and increased apoptosisin the combination group compared to the monotherapy groups.conclusion: nk therapy and pbm each exert anti-tumor effects in crc xenografts; however, their combinationproduces a superior therapeutic response. pbm may serve as a promising adjuvant to enhance nk-basedimmunotherapy in crc.