Indeed, several recent studies demonstrate a striking potential of combining HDAC inhibitors with anti-PD-L1, reducing tumour growth and survival in melanoma, breast cancer, lung cancer and hepatocellular carcinoma models (Woods et al. 2015; Booth et al. 2017; Llopiz et al. 2019; Li et al. 2021). This evidence concerns the gene HDAC9 and hepatocellular carcinoma.