CTLA4 and cancer: To investigate whether [177Lu]Lu-DUNP19 therapy could synergize with immune checkpoint inhibitors, we combined [177Lu]Lu-DUNP19 RIT with immune checkpoint blockade (anti-CTLA4 + anti-PD1) in the syngeneic MC38 colorectal cancer model (LRRC15- cancer cells, LRRC15+ stroma) (Fig. 7).