biostudies-literatureGalsky MDNCI NIH HHSF Hoffman-La Roche, Ltd476-486https://www.ebi.ac.uk/biostudies/studies/S-EPMC11962399biostudies-literatureUnknown13(4)Testing for PD-L1 expression by IHC is used to predict immune checkpoint blockade (ICB) benefits but has performed inconsistently in urothelial cancer clinical trials. Different approaches are used for PD-L1 IHC. We analyzed paired PD-L1 IHC data on urothelial cancer samples using the SP142 and 22C3 assays from the phase III IMvigor130 trial and found discordant findings summarized by four phenotypes: PD-L1 positive by both assays, PD-L1 positive by the SP142 assay only, PD-L1 positive by the 22C3 assay only, and PD-L1 negative by both assays double negative. PD-L1 positive by both assays and PD-L1 positive by the SP142 assay only urothelial cancers were associated with more favorable ICB outcomes and increased dendritic cell (DC) infiltration. SP142 PD-L1 staining co-localized with DC-LAMCancer immunology researchDifferent PD-L1 Assays Reveal Distinct Immunobiology and Clinical Outcomes in Urothelial Cancer.PMC119623992016274T32 CA078207Izadmehr SKikuchi EMellman IKoeppen HDavid JMBernhard SDavis IDRishipathak DAnker JFJohnston RJGrande EGupta SVan Elzen RDe Santis MBanchereau RSanjabi SGnjatic SMariathasan SGalsky MDYuen KBamias APeterson MRoels JArranz JAGuan XKockx MWilliams PfalseDifferent PD-L1 Assays Reveal Distinct Immunobiology and Clinical Outcomes in Urothelial Cancer.Testing for PD-L1 expression by IHC is used to predict immune checkpoint blockade (ICB) benefits but has performed inconsistently in urothelial cancer clinical trials. Different approaches are used for PD-L1 IHC. We analyzed paired PD-L1 IHC data on urothelial cancer samples using the SP142 and 22C3 assays from the phase III IMvigor130 trial and found discordant findings summarized by four phenotypes: PD-L1 positive by both assays, PD-L1 positive by the SP142 assay only, PD-L1 positive by the 22C3 assay only, and PD-L1 negative by both assays double negative. PD-L1 positive by both assays and PD-L1 positive by the SP142 assay only urothelial cancers were associated with more favorable ICB outcomes and increased dendritic cell (DC) infiltration. SP142 PD-L1 staining co-localized with DC-LAM2025-01-01T00:00:00Z2025 Apr2026-06-01T18:08:47.249Z2025-07-01T03:05:28.645ZS-EPMC119623993985327810.1158/2326-6066.CIR-24-0649