Another study revealed a higher abundance of inflammatory cells, such as dendritic cells, monocytes, macrophages, and neutrophils, in fecal samples of progressors than non-progressors in a cohort of melanoma patients receiving the anti-PD-1 antibodies, which implies increased activation of inflammatory immune responses within the intestinal mucosa in the subgroup with poor clinical outcomes [2]. This evidence concerns the gene PDCD1 and melanoma.