PDCD1 and hepatocellular carcinoma: Male C57Bl/6 mice bearing SQ HCC tumors were treated with intratumoral injections (once weekly for 3 weeks) of MMR (1 × 102 TCID50), with or without IP ICB (anti-PD-1 and anti-CTLA-4 antibodies at 5 mg/kg, twice per week for 3 weeks) (Figure 4A).