In addition, we highlight a common immune-related adverse event of anti-PD-1, eosinophilia, as a possible biomarker of response and using TCGA data analysis, provide proof-of-concept for tumor expression of the eosinophil-related gene SIGLEC8, as a promising powerful predictor of prognosis for papillary renal cell carcinoma patients. Here, SIGLEC8 is linked to Increased total eosinophil count.