- Akkermansia muciniphila supplementation was shown to restore anti-PD-1 responses in preclinical models.- Probiotic mixtures like Prohep were shown to suppress HCC growth in preclinical models.- An ongoing clinical trial, NCT05032014, is investigating the potential of probiotics to enhance the efficacy of PD-1 inhibitors in liver cancer patients. Here, PDCD1 is linked to hepatocellular carcinoma.