title: Frequent PD-L1 expression in testicular germ cell tumors.
abstract: BACKGROUND
  Many testicular germ cell cancers are curable despite metastatic disease, but about 10-15% of patients fail cisplatin-based first-line treatment. Immunotherapy is considered as additional treatment approach for these patients. Inhibition of the interaction between Programmed Death Receptor 1 (PD-1) and Programmed Death Receptor Ligand 1 (PD-L1) enhances T-cell responses in vitro and mediates clinical antitumour activity. We analysed the expression of PD-L1 in testicular germ cell tumours to evaluate its potential as target for immunotherapeutic strategies.
  
  
  METHODS
  Immunohistochemistry was performed in 479 formalin-fixed paraffin-embedded specimens using a rabbit monoclonal antibody (E1L3N). The tissue microarray consisted of 208 pure seminomas, 121 non-seminomas, 20 intratubular germ cell neoplasia unclassified (IGCNU) and 20 specimens of non-neoplastic testicular tissue.
  
  
  RESULTS
  Programmed Death Receptor Ligand-1 expression was found in 73% of all seminomas and in 64% of all non-seminomas. None of 20 IGCNU and none of 20 normal tissue specimens exhibited PD-L1 expression. PD-L1 positive stromal cells were only detected in seminomas, but not in non-seminomas. The anti PD-L1 antibody showed a pre-dominantly membranous staining pattern in testicular tumour cells, as well as expression in stromal cells.
  
  
  CONCLUSIONS
  This frequent expression of PD-L1 in human testicular germ cell tumours suggests that patients with testicular germ cell tumours could profit from immunotherapeutic strategies using anti-PD1 and anti-PDL1 antibodies.
authors.affiliation: Department of Urology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: C D
authors.initials: CD
authors.lastname: Fankhauser
authors.affiliation: Department of Oncology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Curioni-Fontecedro
authors.affiliation: Institute of Surgical Pathology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: V
authors.initials: V
authors.lastname: Allmann
authors.affiliation: Department of Oncology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Beyer
authors.affiliation: Institute of Surgical Pathology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: V
authors.initials: V
authors.lastname: Tischler
authors.affiliation: Department of Urology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Sulser
authors.affiliation: Institute of Surgical Pathology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Moch
authors.affiliation: Institute of Surgical Pathology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: P K
authors.initials: PK
authors.lastname: Bode
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D060890:B7-H1 Antigen / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009373:Neoplasms, Germ Cell and Embryonal / Q000453:epidemiology* / Q000378:metabolism* / Q000473:pathology; D018239:Seminoma / Q000453:epidemiology / Q000378:metabolism / Q000473:pathology; D013736:Testicular Neoplasms / Q000453:epidemiology* / Q000378:metabolism* / Q000473:pathology; D013737:Testis / Q000378:metabolism / Q000473:pathology; D046888:Tissue Array Analysis; D055815:Young Adult
chemical_list: D060890:B7-H1 Antigen; C423236:CD274 protein, human