Experimental Lung Metastases in Mice Are More Effectively Inhibited by Blockade of IL23R than IL23

Tumor-induced immunosuppression is mediated through various mechanisms including engagement of immune checkpoint receptors on effector cells, function of immunoregulatory cells such as Tregs and MDSCs, and deployment of immunosuppressive cytokines such as TGFβ and IL10. IL23 is a cytokine that negatively affects antitumor immunity. In this study, we investigated whether IL23-deficient (IL23p19-/-) and IL23R-deficient (IL23R-/-) mice phenocopied each other, with respect to their tumor control. We found that IL23R-/- mice had significantly fewer lung metastases compared to IL23p19-/- mice across three different experimental lung metastasis models (B16F10, LWT1, RM-1). Similarly, IL23R blocking antibodies were more effective than antibodies neutralizing IL23 in suppressing experimental lung metastases. The anti-metastatic activity of anti-IL23R was dependent on NK cells and IFNγ but independent of CD8+ T cells, CD4+ T cells, activating Fc receptors and IL12. Furthermore, our data suggest this increased antitumor efficacy was due to an increase in the proportion of IFNγ-producing NK cells in the lungs of B16F10 tumor-bearing mice. Anti-IL23R, but not anti-IL23p19, partially suppressed lung metastases in tumor-bearing mice neutralized for IL12p40. Collectively, our data implies that IL23R has tumor-promoting effects that are partially independent of IL23p19. Blocking IL23R may be more effective than neutralizing IL23 in the suppression of tumor metastases.