Conroy, Jeffrey MPabla, SarabjotNesline, Mary KGlenn, Sean TPapanicolau-Sengos, AntoniosBurgher, BlakeAndreas, JonathanGiamo, VincentWang, YirongLenzo, Felicia LBshara, WiamKhalil, MayaDy, Grace KMadden, Katherine GShirai, KeisukeDragnev, KonstantinTafe, Laura JZhu, JasonLabriola, MatthewMarin, DanieleMcCall, Shannon JClarke, JeffreyGeorge, Daniel JZhang, TianZibelman, MatthewGhatalia, PoojaAraujo-Fernandez, Isabelde la Cruz-Merino, LuisSingavi, ArunGeorge, BenMacKinnon, Alexander CThompson, JonathanSingh, RajbirJacob, RobinKasuganti, DeepaShah, NeelDay, RogerGalluzzi, LorenzoGardner, MarkMorrison, Carl2023-01-252023-01-252019-01-24http://hdl.handle.net/10668/13457PD-L1 immunohistochemistry (IHC) has been traditionally used for predicting clinical responses to immune checkpoint inhibitors (ICIs). However, there are at least 4 different assays and antibodies used for PD-L1 IHC, each developed with a different ICI. We set to test if next generation RNA sequencing (RNA-seq) is a robust method to determine PD-L1 mRNA expression levels and furthermore, efficacy of predicting response to ICIs as compared to routinely used, standardized IHC procedures. A total of 209 cancer patients treated on-label by FDA-approved ICIs, with evaluable responses were assessed for PD-L1 expression by RNA-seq and IHC, based on tumor proportion score (TPS) and immune cell staining (ICS). A subset of serially diluted cases was evaluated for RNA-seq assay performance across a broad range of PD-L1 expression levels. Assessment of PD-L1 mRNA levels by RNA-seq demonstrated robust linearity across high and low expression ranges. PD-L1 mRNA levels assessed by RNA-seq and IHC (TPS and ICS) were highly correlated (p  Measurement of PD-L1 mRNA expression by RNA-seq is comparable to PD-L1 expression by IHC both analytically and clinically in predicting ICI response. RNA-seq has the added advantages of being amenable to standardization and avoidance of interpretation bias. PD-L1 by RNA-seq needs to be validated in future prospective ICI clinical studies across multiple histologies.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/AtezolizumabAvelumabBiomarkerDurvalumabNivolumabPD-L1Pembrolizumabcancer immunotherapyAntineoplastic Agents, ImmunologicalB7-H1 AntigenHumansImmunohistochemistryNeoplasmsRNA, MessengerRNA-Seqresearch article30678715open access10.1186/s40425-018-0489-52051-1426PMC6346512https://jitc.bmj.com/content/jitc/7/1/18.full.pdfhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC6346512/pdf