PD-L1 immunohistochemistry on baseline TURBT specimens
tumor
CPS, TUMOR, INFILTRATING
Immunohistochemistry for PD-L1 was performed in the Department of Pathology at the Mount Sinai Hospital using the 22C3 antibody clone. PD-L1 expression was quantified by a single genitourinary pathologist (G.K.H.) blinded to clinical outcome data using the combined positive score (CPS), defined as the percentage of PD-L1-expressing tumor and infiltrating immune cells relative to the total number of tumor cells. A cutpoint of CPS ≥ 10 was used to define ‘high’ PD-L1 expression as per previous studies in UC