title: Prognostic significance of interferon regulating factor 4 (IRF4) in node-negative breast cancer.
abstract: OBJECTIVE
  The transcription factor IRF4 regulates immunoglobulin class switch recombination as well as plasma cell differentiation. We examined the prognostic significance of IRF4 expression in node-negative breast cancer (BC).
  
  
  METHODS
  IRF4 expression was evaluated by immunostaining in a cohort of 197 node-negative BC patients not treated in adjuvant setting, referred to as Mainz cohort. The prognostic significance of immunohistochemically determined IRF4 expression for metastasis-free survival (MFS) was examined by Kaplan-Meier survival analysis as well as univariate and multivariate Cox analysis adjusted for age, pT stage, histological grade, ER, and HER2 status. For verification of immunohistochemical results, IRF4 mRNA expression was evaluated using microarray-based gene expression profiling in four previously published cohorts (Mainz, Rotterdam, Transbig, Yu) consisting of 824 node-negative breast cancer patients in total, who were not treated with adjuvant therapy. The prognostic significance of IRF4 mRNA expression on metastasis-free survival (MFS) was examined by univariate and multivariate Cox analysis in the Mainz cohort and by a meta-analysis of all node-negative BC patients and different molecular subtypes. IRF4 mRNA levels were compared to immunohistochemically determined IRF4 expression in 140 patients of the Mainz cohort using Spearman correlation.
  
  
  RESULTS
  Immunohistochemically determined high IRF4 expression was associated with higher MFS in univariate Cox regression (HR 0.178, 95% CI 0.070-0.453, p < 0.001). IRF4 maintained its significance independently of established clinical factors for MFS (HR 0.088, 95% CI 0.033-0.232, p < 0.001). Immunohistochemically, determined IRF4 correlated moderately with IRF4 mRNA expression (ρ = 0.589). Higher expression of IRF4 was associated with better MFS in a meta-analysis of the total cohort (HR 0.438, 95% CI 0.307-0.623, p < 0.001). Prognostic significance was more pronounced in the HER2+molecular subtype (HR 0.215, 95% CI 0.090-0.515, p = 0.001) as compared to the luminal A (HR 0.549, 95% CI 0.248-1.215, p = 0.139), luminal B (HR 0.444, 95% CI 0.215-0.916, p = 0.028), and basal-like subtypes (HR 0.487, 95% CI 0.269-0.883, p = 0.018). Further, IRF4 expression showed independent prognostic significance in a multivariate analysis of the Mainz cohort (HR 0.236, 95% CI 0.105-0.527, p < 0.001).
  
  
  CONCLUSIONS
  IRF4 had independent prognostic significance in node-negative BC. Higher expression of IRF4 was associated with improved outcome. The prognostic impact differed between diverse molecular subtypes and was most pronounced in HER2+breast cancer.
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany. anne-sophie.heimes@unimedizin-mainz.de.
authors.forename: Anne-Sophie
authors.identifier: http://orcid.org/0000-0001-5472-5224
authors.initials: AS
authors.lastname: Heimes
authors.affiliation: Department of Statistics, TU Dortmund University, Dortmund, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Madjar
authors.affiliation: Leibniz Research Centre for Working Environment and Human Factors (IfADo), TU Dortmund University, Dortmund, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Edlund
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany.
authors.forename: M J
authors.initials: MJ
authors.lastname: Battista
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Almstedt
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Gebhard
authors.affiliation: Institute of Pathology, University Medical Center, Mainz, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Foersch
authors.affiliation: Department of Statistics, TU Dortmund University, Dortmund, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Rahnenführer
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Brenner
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hasenburg
authors.affiliation: Leibniz Research Centre for Working Environment and Human Factors (IfADo), TU Dortmund University, Dortmund, Germany.
authors.forename: J G
authors.initials: JG
authors.lastname: Hengstler
authors.affiliation: Department of Obstetrics and Gynecology, University Medical Center, Langenbeckstr. 1, 55131, Mainz, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schmidt
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D050835:Interferon Regulatory Factors / Q000032:analysis / Q000096:biosynthesis*; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D011379:Prognosis; D016016:Proportional Hazards Models; D059467:Transcriptome; D000099218:Interferon Regulatory Factor-4
chemical_list: D014408:Biomarkers, Tumor; D050835:Interferon Regulatory Factors; D000099218:Interferon Regulatory Factor-4
keywords: Anti-tumor immunity; Breast cancer; IRF4; Tumor-infiltrating lymphocytes (TILs)