Renin-angiotensin system (RAS) inhibitors (RASi)—widely prescribed for the treatment of
cardiovascular diseases—have considerable potential in oncology. The RAS plays a crucial
role in cancer biology and affects tumor growth and dissemination directly and indirectly by
remodeling the tumor microenvironment. We review clinical data on the benefit of RASi in
primary and metastatic tumors and propose that, by activating immunostimulatory pathways,
these inhibitors can enhance immunotherapy of cancer.