Mutational status of TP53 or ARID1A was not significantly associated with response to pembrolizumab in HCC (p = 0.34 and 0.063, respectively), but mutations in TP53 and ARID1A genes were more frequent in responders than non-responders (odd ratios = 4.55 and 10.4, respectively). The gene discussed is ARID1A; the disease is hepatocellular carcinoma.