These include: i) as large-sized prospective investigations are missing, the incidence of irAEs varies significantly across studies, as does the tumor type (melanoma being of better prognostic than NSCLC), the tumor staging (over-representation of stages III versus stages IV), and the type of ICI used (anti-CTLA4 being more toxic than anti-PD-1/PD-L1). The gene discussed is PDCD1; the disease is melanoma.