title: Transcriptome-wide studies of merkel cell carcinoma and validation of intratumoral CD8+ lymphocyte invasion as an independent predictor of survival.
abstract: OBJECTIVE
  Merkel cell carcinoma (MCC) is a polyomavirus-associated skin cancer that is frequently lethal and lacks established prognostic biomarkers. This study sought to identify biomarkers that improve prognostic accuracy and provide insight into MCC biology.
  
  
  METHODS
  Gene expression profiles of 35 MCC tumors were clustered based on prognosis. The cluster of genes overexpressed in good-prognosis tumors was tested for biologic process enrichment. Relevant mRNA expression differences were confirmed by quantitative polymerase chain reaction and immunohistochemistry. An independent set of 146 nonoverlapping MCC tumors (median follow-up, 25 months among 116 living patients) was employed for biomarker validation. Univariate and multivariate Cox regression analyses were performed.
  
  
  RESULTS
  Immune response gene signatures were prominent in patients with good prognoses. In particular, genes associated with cytotoxic CD8+ lymphocytes were overexpressed in tumors from patients with favorable prognoses. In the independent validation set, cases with robust intratumoral CD8+ lymphocyte infiltration had improved outcomes (100% MCC-specific survival, n = 26) compared with instances characterized by sparse infiltration (60% survival, n = 120). Only stage and intratumoral CD8 infiltration (but not age, sex, or CD8+ lymphocytes localized to the tumor-stroma interface) were significant in both univariate and multivariate Cox regression analyses. Notably, traditional histologic identification of tumor-infiltrating lymphocytes was not a significant independent predictor of survival.
  
  
  CONCLUSIONS
  Intratumoral CD8+ lymphocyte infiltration can be readily assessed on paraffin-embedded tissue, is independently associated with improved MCC-specific survival, and therefore, may provide prognostic information that enhances established MCC staging protocols.
authors.affiliation: University of Washington, Seattle, WA 98109, USA.
authors.forename: Kelly G
authors.initials: KG
authors.lastname: Paulson
authors.forename: Jayasri G
authors.initials: JG
authors.lastname: Iyer
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Tegeder
authors.forename: Renee
authors.initials: R
authors.lastname: Thibodeau
authors.forename: Janell
authors.initials: J
authors.lastname: Schelter
authors.forename: Shinichi
authors.initials: S
authors.lastname: Koba
authors.forename: David
authors.initials: D
authors.lastname: Schrama
authors.forename: William T
authors.initials: WT
authors.lastname: Simonson
authors.forename: Bianca D
authors.initials: BD
authors.lastname: Lemos
authors.forename: David R
authors.initials: DR
authors.lastname: Byrd
authors.forename: David M
authors.initials: DM
authors.lastname: Koelle
authors.forename: Denise A
authors.initials: DA
authors.lastname: Galloway
authors.forename: J Helen
authors.initials: JH
authors.lastname: Leonard
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Madeleine
authors.forename: Zsolt B
authors.initials: ZB
authors.lastname: Argenyi
authors.forename: Mary L
authors.initials: ML
authors.lastname: Disis
authors.forename: Juergen C
authors.initials: JC
authors.lastname: Becker
authors.forename: Michele A
authors.initials: MA
authors.lastname: Cleary
authors.forename: Paul
authors.initials: P
authors.lastname: Nghiem
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001317:Austria; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D015266:Carcinoma, Merkel Cell / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology / Q000401:mortality / Q000473:pathology; D016000:Cluster Analysis; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016612:Paraffin Embedding; D011379:Prognosis; D016016:Proportional Hazards Models; D011793:Queensland; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018570:Risk Assessment; D012307:Risk Factors; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology / Q000401:mortality / Q000473:pathology; D015996:Survival Rate; D013997:Time Factors; D014861:Washington