https://gdefiner.net/ Project: "Gender Difference in sidE eFfects of ImmuNotherapy: a possible clue to optimize cancEr tReatment" (G-DEFINER). Project SOPs. (DOI of the Study Protocol: 10.5281/zenodo.6397628) This is a multicenter observational prospective clinical study aimed at investigating the inequalities between female (F) and male (M) patients in the development of immune-related adverse events (irAEs) associated with immunotherapy treatment. The evaluation of the differences in terms of irAEs incidence concerning biological aspects will be integrated by the exploration of their gender dimension. These Standard Operating Procedures (SOPs) are documents containing detailed written instructions relating to common or important tasks and practices of the G-DEFINER project. G-DEFINER adopted the SOPs with the aim to achieve efficiency, quality output and uniformity during study conduction.