As demonstrated in clinical trials, metformin can inhibit the trained immunity property of BCG by reducing the production of IL‐6 and Tumor necrosis factor‐α (TNF‐α).[21] To investigate the contribution of trained immunity to the anti‐HCC effect of BCG, metformin was administered alone or in combination with BCG to HCC mice. Here, IL6 is linked to hepatocellular carcinoma.