Specifically, C3a levels were higher in all three cohorts of cancer patients compared to HCs (irMyositis: padj = 0.048; 95% CI, 9.54–33.99; irNeuropathy: padj = < 0.001; 95% CI, 20.50–42.73; CCs: padj < 0.0001; 95% CI, 34.07–52.50; Fig. 1A), while C3 levels were only increased in patients with irNeuropathy compared to HCs (irNeuropathy: padj = 0.04, 95% CI, 3.36–28.73, Fig. 1A). Here, C3 is linked to cancer.