title: B7-H1 expression in malignant pleural mesothelioma is associated with sarcomatoid histology and poor prognosis.
abstract: BACKGROUND
  B7 homolog 1 (B7-H1; aka programmed cell death 1 ligand 1) is a negative costimulatory molecule that is associated with poor prognosis in many tumor types. Given the poor prognosis and the limited treatments available for mesothelioma, we decided to examine B7-H1 expression and its association with survival in patients with mesothelioma.
  
  
  METHODS
  Expression of B7-H1 was determined in 106 patients using a mouse monoclonal antihuman B7-H1 (clone 5H1-A3) antibody with immunohistochemistry. Positive expression was defined as ≥5% positively stained cells. Clinicopathologic features and survival were compared between B7-H1-positive and B7-H1-negative groups.
  
  
  RESULTS
  Malignant mesotheliomas of 42 patients (40%) expressed B7-H1. Patients with B7-H1-postive tumors were less likely to be offered or undergo therapeutic surgery (p = 0.03). All sarcomatoid mesotheliomas except one desmoplastic subtype expressed B7-H1. Survival was significantly decreased for patients whose tumors expressed B7-H1 (5 months median, 2-9.5 months interquartile range) compared with those whose tumors did not (14.5 months, 9.25-19 months; p < 0.0001). In a multivariate model, B7-H1 expression and sarcomatoid mesothelioma remained significantly associated with worse survival (risk ratio 1.71, 95% confidence interval 1.03-2.78 [p = 0.04] and risk ratio 2.18, 1.08-4.23 [p = 0.03], respectively).
  
  
  CONCLUSIONS
  B7-H1 is expressed in a substantial proportion of malignant pleural mesotheliomas and is associated with poor survival. Almost all malignant pleural mesotheliomas with sarcomatoid differentiation expressed B7-H1. The expression of B7-H1 may have important therapeutic implications for the management of malignant pleural mesothelioma.
authors.affiliation: Division of Medical Oncology, Mayo Clinic, Rochester, MN. Electronic address: mansfield.aaron@mayo.edu.
authors.forename: Aaron Scott
authors.initials: AS
authors.lastname: Mansfield
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN.
authors.forename: Anja C
authors.initials: AC
authors.lastname: Roden
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Tobias
authors.initials: T
authors.lastname: Peikert
authors.affiliation: Department of Urology, Mayo Clinic, Rochester, MN; Department of Immunology, Mayo Clinic, Rochester, MN.
authors.forename: Yuri M
authors.initials: YM
authors.lastname: Sheinin
authors.affiliation: Department of Urology, Mayo Clinic, Rochester, MN.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Harrington
authors.affiliation: Department of Immunology, Mayo Clinic, Rochester, MN.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Krco
authors.affiliation: Department of Urology, Mayo Clinic, Rochester, MN.
authors.forename: Haidong
authors.initials: H
authors.lastname: Dong
authors.affiliation: Department of Urology, Mayo Clinic, Rochester, MN.
authors.forename: Eugene D
authors.initials: ED
authors.lastname: Kwon
mesh_terms: D000368:Aged; D060890:B7-H1 Antigen / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D008654:Mesothelioma / Q000737:chemistry* / Q000473:pathology*; D008875:Middle Aged; D010997:Pleural Neoplasms / Q000737:chemistry* / Q000473:pathology*; D011379:Prognosis; D015996:Survival Rate
chemical_list: D060890:B7-H1 Antigen; C423236:CD274 protein, human