CTLA4 and Pruritus: RRs for any grade and high grade pruritus developed after PD-1/-L1 inhibitor treatment were 0.65 (95%CI 0.56-0.75, p < 0.00001) (Supplementary Figure 3A) and 0.15 (95%CI 0.03-0.89, p = 0.04) (Supplementary Figure 3B) respectively compared to CTLA-4 inhibitor treatment.