CD274 and hepatocellular carcinoma: High levels of CAF‐secreted IL‐6 induced tumor immunosuppression by recruiting MDSCs and upregulating PD‐L1 expression, impairing the efficacy of anti‐PD‐L1 immunotherapy against hepatocellular carcinoma (HCC), and IL‐6 blockade increased the efficacy of PD‐L1 treatment 40.