H. pylori seropositivity is associated with reduced effectiveness of anti-PD1 immunotherapy in patients with NSCLC. H. pylori infection affects not only DC function but also that of monocytes and/or macrophages. Indeed, in humans, it observed a decreased number of cells from the monocyte lineage and a substantially decreased expression of genes induced by type I interferon, IFN-γ, and IL-6 in the tumors of infected patients with NSCLC undergoing anti-PD1 treatment. This evidence concerns the gene PDCD1 and non-small cell lung carcinoma.