Abstract
Nowadays, immunotherapy is widely used to treat different cancer types as it boosts the body's natural defenses against the malignancy, with lower risk of adverse events compared to the traditional treatments. The immune system is able to control cancer growth but, unfortunately, many cancers take advantage of immune checkpoints pathways for the immune evasion. An intricate network of factors including tumor, host and environmental variables influence the individual response to immune checkpoints' inhibitors. Between them, the gut microbiota (GM) has recently gained increasing attention because of its emerging role as a modulator of the immune response. Several studies analyzed the diversities between immunotherapy-sensitive and immunotherapy-resistant cohorts, evidencing that particular GM profiles were closely associated to treatment effect. In addition, other data documented that interventional GM modulation could effectively enhance efficacy and relieve resistance during immunotherapy treatment. Diet represents one of the major GM determinants, and ongoing studies are examining the role of the food-gut axis in immunotherapy treatment. Here, we review recent studies that described how variations of the GM affects patient's responsivity to anti-cancer immunotherapy and how diet-related factors impact on the GM modulation in cancer, outlining potential future clinical directions of these recent findings.