CTLA4 and cancer: Given the approved usage of dual immune checkpoint inhibitors targeting PD-1/PD-L1 and CTLA-4 across a range of malignancies, we categorized the included trials into two distinct groups: “anti-PD-1/PD-L1 plus anti-CTLA-4” and “anti-PD-1/PD-L1 plus another IO therapy.” In comparison to PD-1/PD-L1 inhibitor monotherapy, the addition of a CTLA-4 inhibitor demonstrated an increase in the response rate (OR = 1.29 [95% CI 1.15–1.44]) and potential extension of survival without progression (HR = 0.91 [95% CI 0.86–0.96]).