title: Differential Expression of Immune-Regulatory Genes Associated with PD-L1 Display in Melanoma: Implications for PD-1 Pathway Blockade.
abstract: OBJECTIVE
  Blocking the immunosuppressive PD-1/PD-L1 pathway has antitumor activity in multiple cancer types, and PD-L1 expression on tumor cells and infiltrating myeloid cells correlates with the likelihood of response. We previously found that IFNG (interferon-gamma) was overexpressed by tumor-infiltrating lymphocytes in PD-L1(+) versus PD-L1(-) melanomas, creating adaptive immune resistance by promoting PD-L1 display. This study was undertaken to identify additional factors in the PD-L1(+) melanoma microenvironment coordinately contributing to immunosuppression.
  
  
  METHODS
  Archived, formalin-fixed paraffin-embedded melanoma specimens were assessed for PD-L1 protein expression at the tumor cell surface with IHC. Whole-genome expression analysis, quantitative (q)RT-PCR, IHC, and functional in vitro validation studies were used to assess factors differentially expressed in PD-L1(+) versus PD-L1(-) melanomas.
  
  
  RESULTS
  Functional annotation clustering based on whole-genome expression profiling revealed pathways upregulated in PD-L1(+) melanomas, involving immune cell activation, inflammation, and antigen processing and presentation. Analysis by qRT-PCR demonstrated overexpression of functionally related genes in PD-L1(+) melanomas, involved in CD8(+) T-cell activation (CD8A, IFNG, PRF1, and CCL5), antigen presentation (CD163, TLR3, CXCL1, and LYZ), and immunosuppression [PDCD1 (PD-1), CD274 (PD-L1), and LAG3, IL10]. Functional studies demonstrated that some factors, including IL10 and IL32-gamma, induced PD-L1 expression on monocytes but not tumor cells.
  
  
  CONCLUSIONS
  These studies elucidate the complexity of immune checkpoint regulation in the tumor microenvironment, identifying multiple factors likely contributing to coordinated immunosuppression. These factors may provide tumor escape mechanisms from anti-PD-1/PD-L1 therapy, and should be considered for cotargeting in combinatorial immunomodulation treatment strategies.
authors.affiliation: Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland. Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland. Department of Oncology, Sidney Kimmel Comprehensive Cancer Center and Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Janis M
authors.initials: JM
authors.lastname: Taube
authors.affiliation: Department of Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Young
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Tracee L
authors.initials: TL
authors.lastname: McMiller
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Shuming
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: January T
authors.initials: JT
authors.lastname: Salas
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Theresa S
authors.initials: TS
authors.lastname: Pritchard
authors.affiliation: Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Haiying
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Alan K
authors.initials: AK
authors.lastname: Meeker
authors.affiliation: The Lowe Family Genomics Core, Sidney Kimmel Comprehensive Cancer Center and Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Jinshui
authors.initials: J
authors.lastname: Fan
authors.affiliation: The Lowe Family Genomics Core, Sidney Kimmel Comprehensive Cancer Center and Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Chris
authors.initials: C
authors.lastname: Cheadle
authors.affiliation: The Lowe Family Genomics Core, Sidney Kimmel Comprehensive Cancer Center and Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Alan E
authors.initials: AE
authors.lastname: Berger
authors.affiliation: Department of Oncology, Sidney Kimmel Comprehensive Cancer Center and Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Drew M
authors.initials: DM
authors.lastname: Pardoll
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland. stopali1@jhmi.edu.
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Topalian
mesh_terms: D015703:Antigens, CD / Q000235:genetics; D060890:B7-H1 Antigen / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D056747:Immunomodulation / Q000235:genetics*; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology / Q000378:metabolism; D008545:Melanoma / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D061026:Programmed Cell Death 1 Receptor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D059016:Tumor Microenvironment / Q000235:genetics / Q000276:immunology; D000093322:Lymphocyte Activation Gene 3 Protein
chemical_list: D015703:Antigens, CD; D060890:B7-H1 Antigen; D018925:Chemokines; D016207:Cytokines; D008024:Ligands; D061026:Programmed Cell Death 1 Receptor; D000093322:Lymphocyte Activation Gene 3 Protein; C000720326:Lag3 protein, human