title: What does PD-L1 positive or negative mean?
abstract: Expression of the programmed death-1 (PD-1) ligand 1 (PD-L1) is used to select patients and analyze responses to anti-PD-1/L1 antibodies. The expression of PD-L1 is regulated in different ways, which leads to a different significance of its presence or absence. PD-L1 positivity may be a result of genetic events leading to constitutive PD-L1 expression on cancer cells or inducible PD-L1 expression on cancer cells and noncancer cells in response to a T cell infiltrate. A tumor may be PD-L1 negative because it has no T cell infiltrate, which may be reversed with an immune response. Finally, a tumor that is unable to express PD-L1 because of a genetic event will always be negative for PD-L1 on cancer cells.
authors.affiliation: Department of Medicine, Division of Hematology-Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA 90095 aribas@mednet.ucla.edu.|Jonsson Comprehensive Cancer Center (JCCC), University of California, Los Angeles (UCLA), Los Angeles, CA 90095.
authors.forename: Antoni
authors.initials: A
authors.lastname: Ribas
authors.affiliation: Department of Medicine, Division of Hematology-Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA 90095.|Jonsson Comprehensive Cancer Center (JCCC), University of California, Los Angeles (UCLA), Los Angeles, CA 90095.
authors.forename: Siwen
authors.initials: S
authors.lastname: Hu-Lieskovan
mesh_terms: D000818:Animals; D060890:B7-H1 Antigen / Q000235:genetics / Q000276:immunology*; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000276:immunology*; D009369:Neoplasms / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D061026:Programmed Cell Death 1 Receptor / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology
chemical_list: D060890:B7-H1 Antigen; C423236:CD274 protein, human; D009363:Neoplasm Proteins; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor