To determine the effect of CCL5-deficiency on anti-PD-1 Ab resistance in CRC, we intraperitoneally injected 200 μg anti-PD-1 Ab into CCL5+/+ and CCL5−/− mice every 3–4 days from day 3 to day 16 after tumor challenge. This evidence concerns the gene CCL5 and colorectal carcinoma.