Further, PBMC-derived human MDSCs express TLR9, and treatment with class C TLR9 agonists (ODN2395 and SD101) reduced the expansion of MDSC population. Regional TLR9 agonist infusion along with systemic anti-PD-1 therapy improved control of LM. With effective delivery, TLR9 agonists have the potential to favorably reprogram the liver TME through reduction of MDSCs and favorable macrophage polarization, which may improve responsiveness to systemic CPI therapy.