title: Human melanoma metastases demonstrate nonstochastic site-specific antigen heterogeneity that correlates with T-cell infiltration.
abstract: OBJECTIVE
  Metastasis heterogeneity presents a significant obstacle to the development of targeted cancer therapeutics. In this study, we sought to establish from a large series of human melanoma metastases whether there exists a determined pattern in tumor cellular heterogeneity that may guide the development of future targeted immunotherapies.
  
  
  METHODS
  From a cohort of 1,514 patients with metastatic melanoma, biopsies were procured over a 17-year period from 3,086 metastatic tumors involving various anatomic sites. To allow specific tumor cell profiling, we used established immunohistochemical methods to perform semiquantitative assessment for a panel of prototypic melanocyte differentiation antigens (MDA), including gp100, MART-1, and tyrosinase. To gain insight into the endogenous host immune response against these tumors, we further characterized tumor cell expression of MHC I and MHC II and, also, the concomitant CD4(+) and CD8(+) T-cell infiltrate.
  
  
  RESULTS
  Tumor cell profiling for MDA expression demonstrated an anatomic site-specific pattern of antigen expression that was highest in brain, intermediate in soft tissues/lymph nodes, and lowest in visceral metastases. Hierarchical clustering analysis supported that melanoma metastases have a phylogenetically determined, rather than a stochastic, pattern of antigen expression that varies by anatomic site. Furthermore, tyrosinase expression was more frequently lost in metastatic sites outside of the brain and was uniquely correlated with both endogenous CD8(+) and CD4(+) T-cell infiltrates.
  
  
  CONCLUSIONS
  Site-specific antigen heterogeneity represents a novel attribute for human melanoma metastases that should be considered in future therapy development and when assessing the responsiveness to antigen-specific immunotherapies.
authors.forename: Edmund K
authors.initials: EK
authors.lastname: Bartlett
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Fetsch
authors.forename: Armando C
authors.initials: AC
authors.lastname: Filie
authors.forename: Andrea
authors.initials: A
authors.lastname: Abati
authors.forename: Seth M
authors.initials: SM
authors.lastname: Steinberg
authors.forename: John R
authors.initials: JR
authors.lastname: Wunderlich
authors.forename: Donald E
authors.initials: DE
authors.lastname: White
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Stephens
authors.forename: Francesco M
authors.initials: FM
authors.lastname: Marincola
authors.forename: Steven A
authors.initials: SA
authors.lastname: Rosenberg
authors.forename: Udai S
authors.initials: US
authors.lastname: Kammula
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism / Q000473:pathology; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism / Q000473:pathology; D016000:Cluster Analysis; D015331:Cohort Studies; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D016246:Lymphocytes, Tumor-Infiltrating / Q000378:metabolism* / Q000473:pathology; D058965:MART-1 Antigen / Q000378:metabolism; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology; D058950:Melanoma-Specific Antigens / Q000145:classification / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000378:metabolism; D009362:Neoplasm Metastasis; D013601:T-Lymphocytes / Q000378:metabolism* / Q000473:pathology; D058951:gp100 Melanoma Antigen / Q000378:metabolism
chemical_list: D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D058965:MART-1 Antigen; D058950:Melanoma-Specific Antigens; D058951:gp100 Melanoma Antigen; D014442:Monophenol Monooxygenase