Telmisartan enhances anti-PD-1 efficacy in MSS colorectal cancer via modulation of PD-L1 and STAT3 signaling

Background

Microsatellite stable (MSS) colorectal cancer (CRC), accounting for over 85% of advanced cases, shows intrinsic resistance to immune checkpoint inhibitors due to an immunosuppressive tumor microenvironment. The renin-angiotensin system (RAS), particularly angiotensin II type 1 receptor (AT1R), has been implicated in tumor progression and immune evasion. This study investigated whether telmisartan, a selective AT1R antagonist, modulates programmed death-ligand 1 (PD-L1) expression and enhances anti-tumor immunity in MSS CRC.