title: PD-L1 Antibodies to Its Cytoplasmic Domain Most Clearly Delineate Cell Membranes in Immunohistochemical Staining of Tumor Cells.
abstract: Blocking the programmed death-1 (PD-1) pathway has clinical benefit in metastatic cancer and has led to the approval of the mAbs pembrolizumab and nivolumab to treat melanoma and nivolumab for non-small cell lung cancer. Expression of PD-L1 on the cell surface of either tumor cells or infiltrating immune cells is associated with a higher likelihood of response to PD-1 blockade in multiple studies. Most mAbs to PD-L1 in use are directed to its extracellular domain and immunohistochemically stain tumor tissue with a mixture of cytoplasmic and membrane staining. Cytoplasmic staining obscures the interpretation of a positive reaction on the tumor cell membrane, and thus affects the accuracy of PD-L1 scoring systems. We developed a mAb to the cytoplasmic domain of PD-L1, 405.9A11 (9A11), which is both more selective for membranous PD-L1 and more sensitive in IHC and Western blotting, compared with previous mAbs specific for the PD-L1 extracellular domain. Here, we compare immunohistochemical staining patterns of PD-L1 expression in five types of tumors, using five PD-L1 mAbs: 9A11, 7G11, and three commercially available mAbs. We demonstrate that 9A11, as well as two other cytoplasmic domain-specific mAbs, E1L3N and SP142, can clearly delineate the membrane of PD-L1-positive cells in formalin-fixed paraffin-embedded tissue and facilitate interpretation of staining results.
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts. Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Mahoney
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Heather
authors.initials: H
authors.lastname: Sun
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts. Center for Immuno-Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Liao
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Ping
authors.initials: P
authors.lastname: Hua
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Marcella
authors.initials: M
authors.lastname: Callea
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Greenfield
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts. Center for Immuno-Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: F Stephen
authors.initials: FS
authors.lastname: Hodi
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Arlene H
authors.initials: AH
authors.lastname: Sharpe
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Sabina
authors.initials: S
authors.lastname: Signoretti
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts. Center for Immuno-Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Rodig
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts. gordon_freeman@dfci.harvard.edu.
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Freeman
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized / Q000276:immunology / Q000494:pharmacology; D060890:B7-H1 Antigen / Q000276:immunology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000276:immunology*; D006801:Humans; D009369:Neoplasms / Q000276:immunology* / Q000473:pathology; D000077594:Nivolumab; D061026:Programmed Cell Death 1 Receptor / Q000276:immunology*; D017434:Protein Structure, Tertiary; D013194:Staining and Labeling; D016610:Tissue Embedding
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D060890:B7-H1 Antigen; C423236:CD274 protein, human; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor; D000077594:Nivolumab; C582435:pembrolizumab