Ilaria Girolami1, Liron Pantanowitz2, Massimo Barberis3, Gaetano Paolino4, Matteo Brunelli4, Elena Vigliar5, Enrico Munari6, Swati Satturwar7, Giancarlo Troncone5, Albino Eccher4. 1. Division of Pathology, Central Hospital Bolzano, Bolzano, Italy. 2. Department of Pathology & Clinical Labs, University of Michigan, Ann Arbor, MI, USA. 3. Division of Pathology, IEO European Institute of Oncology, Milan, Italy. 4. Department of Pathology and Diagnostics, University and Hospital Trust of Verona, Verona, Italy. 5. Department of Public Health, University of Naples Federico II, Naples, Italy. 6. Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy. 7. Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
Abstract
BACKGROUND: Programmed death-ligand 1 (PD-L1) expression with combined positive score (CPS) ≥1 is required for administration of checkpoint inhibitor therapy in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). The 22C3 pharmDx Dako immunohistochemical assay is the one approved as companion diagnostic for pembrolizumab, but many laboratories work on other platforms and/or with other clones, and studies exploring the potential interchangeability of assays have appeared. EVIDENCE FROM THE LITERATURE: After review of the literature, it emerges that the concordance among assays ranges from fair to moderate, with a tendence of assay SP263 to yield a higher quota of positivity and of assay SP142 to stain better immune cells. Moreover, pathologists achieve very good concordance in assessing PD-L1 CPS, particularly with SP263. CONCLUSIONS: Differences in terms of platforms, procedures, and study design still preclude a quantitative synthesis of evidence and clearly further work is needed to draw stronger conclusions on the interchangeability of PD-L1 assays in HNSCC.
BACKGROUND:Programmed death-ligand 1 (PD-L1) expression with combined positive score (CPS) ≥1 is required for administration of checkpoint inhibitor therapy in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). The 22C3 pharmDx Dako immunohistochemical assay is the one approved as companion diagnostic for pembrolizumab, but many laboratories work on other platforms and/or with other clones, and studies exploring the potential interchangeability of assays have appeared. EVIDENCE FROM THE LITERATURE: After review of the literature, it emerges that the concordance among assays ranges from fair to moderate, with a tendence of assay SP263 to yield a higher quota of positivity and of assay SP142 to stain better immune cells. Moreover, pathologists achieve very good concordance in assessing PD-L1 CPS, particularly with SP263. CONCLUSIONS: Differences in terms of platforms, procedures, and study design still preclude a quantitative synthesis of evidence and clearly further work is needed to draw stronger conclusions on the interchangeability of PD-L1 assays in HNSCC.