Targeting TBK1 potentiates oncolytic virotherapy via amplifying ICAM1-mediated NK cell immunity in chemo-resistant colorectal cancer

Background Tumor resistance is the primary reason for treatment failure in patients with cancer, while oncolytic viruses (OVs), as a novel therapy, have been rapidly advancing through clinical evaluation and are typically assessed in recurrent tumors that are refractory to standard chemotherapy. However, whether the adaptive process that fosters chemotherapy resistance influences the efficacy of OV therapy is unknown. Methods We analyzed chemo-resistant colorectal cancer (CRC) using in vitro, in vivo, and patient-derived organoid models to assess sensitivity to OVs. Through RNA sequencing analysis and immunohistochemistry were performed in clinical samples that indicated TANK-binding kinase 1 (TBK1) expression. Using single-cell RNA sequencing, flow cytometry, and in vivo neutralization assays to demonstrate that the combination of TBK1 inhibitor (TBK1i) and OVs reprograms the tumor immune microenvironment, particularly by activating natural killer (NK) cells. Through RNA sequencing analysis, we identified intercellular cell adhesion molecule-1 (ICAM-1) as a potential target responsible for NK cell activation. Subsequently, we designed and conducted rescue experiments, both in vitro and in vivo, to validate the influence of ICAM-1 on NK cell activity. Results We demonstrated that chemo-resistant CRC showed decreased sensitivity to the OV in vitro, in vivo, and patient-derived organoids. Further investigation revealed aberrant activation of TBK1 in chemo-resistant CRC, which mediated the activation of the type I interferon pathway and impaired viral replication. TBK1 inhibition enhanced intratumor viral replication and direct oncolysis effect in vitro and augmented the antitumor immunity elicited by OVs in vivo. Immune cell profiles presented that OV/TBK1i combination reshaped the tumor microenvironment and especially activated the NK cell response. Immune cell depletion studies demonstrated that NK cells were required for the synergistic therapeutic activity of the OV/TBK1i combination. Mechanistically, TBK1 inhibition synergized with VSVΔ51 to increase ICAM1 expression in a RIPK1-dependent manner, promoting NK cell-mediated tumor killing. Conclusion This study presents a promising approach for treating chemo-resistant CRC by combining OVs and TBK1i.