The impact of targeting TRAF2 and NCK-interacting protein kinase (TNIK) on anti-tumor effect and tumor immune environment in c-MYC-high small cell lung cancer

Introduction: Wnt/β-catenin signaling pathway activation contributes to tumorigenesis and chemo-resistance in small cell lung cancer (SCLC), yet clinical attempts to target this pathway have been unsuccessful. TRAF2 and NCK-interacting protein kinase (TNIK), an essential nuclear activator of Wnt/β-catenin target genes, has not yet been validated as a viable therapeutic target in SCLC. Here, we validated that TNIK inhibition is a promising approach for personalized anti-cancer therapy in SCLC. Methods: We correlated the IC50 values of a TNIK inhibitor, NCB-0846 with proteomic profiling (Reverse Phase Protein Array, RPPA) data across 28 SCLC cell lines. Cytokine array analysis was performed to quantify changes in 105 cytokines following TNIK inhibitor treatment. Results: We identified c-MYC expression as a top candidate marker of TNIK inhibition response. In xenograft models of c-MYChigh SCLC, TNIK inhibition led to suppression of tumor growth and a decrease in c-MYC expression. In the clinically aggressive POU2F3 expressing subtype of SCLC, the TNIK inhibitor showed anti-tumor effect by decreasing SOX9 in addition to c-MYC. Furthermore, TNIK inhibition suppressed the production of the immunosuppressive chemokine CCL2 by attenuating its transcription factor FOXK1 in c-MYChigh SCLC cells. Combination of TNIK inhibition and an anti-PD-L1 antibody resulted in greater efficacy and reduced infiltration of immunosuppressive cells infiltration compared with each monotherapy in immunocompetent SCLC in vivo models. Conclusions: TNIK inhibition is more effective in c-MYChigh SCLC, acting through downregulation of c-MYC levels. It also decreases the production of CCL2, supporting the rationale for combination therapy with immune checkpoint inhibitors in c-MYChigh SCLC.