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Immune gene expression profiling reveals heterogeneity in luminal breast tumors

Authors
  • Zhu, Bin1
  • Tse, Lap Ah2
  • Wang, Difei1, 3
  • Koka, Hela1
  • Zhang, Tongwu1
  • Abubakar, Mustapha1
  • Lee, Priscilla2
  • Wang, Feng2
  • Wu, Cherry4
  • Tsang, Koon Ho5
  • Chan, Wing-cheong4
  • Law, Sze Hong5
  • Li, Mengjie2, 6
  • Li, Wentao2
  • Wu, Suyang2
  • Liu, Zhiguang2
  • Huang, Bixia2
  • Zhang, Han1
  • Tang, Eric1
  • Kan, Zhengyan7
  • And 14 more
  • 1 National Cancer Institute, National Institutes of Health, Rockville, MD, USA , Rockville (United States)
  • 2 The Chinese University of Hong Kong, Hong Kong, China , Hong Kong (China)
  • 3 Frederick National Laboratory for Cancer Research, Frederick, MD, USA , Frederick (United States)
  • 4 North District Hospital, Hong Kong, China , Hong Kong (China)
  • 5 Yan Chai Hospital, Hong Kong, China , Hong Kong (China)
  • 6 Vanderbilt University, Nashville, TN, USA , Nashville (United States)
  • 7 Pfizer Oncology Research, San Diego, CA, 92121, USA , San Diego (United States)
  • 8 Pfizer Oncology, Seoul, 04631, South Korea , Seoul (South Korea)
  • 9 Sungkyunkwan University School of Medicine, Seoul, 06351, South Korea , Seoul (South Korea)
  • 10 University of North Carolina at Chapel Hill, Chapel Hill, NC, USA , Chapel Hill (United States)
Type
Published Article
Journal
Breast Cancer Research
Publisher
BioMed Central
Publication Date
Dec 19, 2019
Volume
21
Issue
1
Identifiers
DOI: 10.1186/s13058-019-1218-9
Source
Springer Nature
Keywords
License
Green

Abstract

BackgroundHeterogeneity of immune gene expression patterns of luminal breast cancer (BC), which is clinically heterogeneous and overall considered as low immunogenic, has not been well studied especially in non-European populations. Here, we aimed at characterizing the immune gene expression profile of luminal BC in an Asian population and associating it with patient characteristics and tumor genomic features.MethodsWe performed immune gene expression profiling of tumor and adjacent normal tissue in 92 luminal BC patients from Hong Kong using RNA-sequencing data and used unsupervised consensus clustering to stratify tumors. We then used luminal patients from The Cancer Genome Atlas (TCGA, N = 564) and a Korean breast cancer study (KBC, N = 112) as replication datasets.ResultsBased on the expression of 130 immune-related genes, luminal tumors were stratified into three distinct immune subtypes. Tumors in one subtype showed higher level of tumor-infiltrating lymphocytes (TILs), characterized by T cell gene activation, higher expression of immune checkpoint genes, higher nonsynonymous mutation burden, and higher APOBEC-signature mutations, compared with other luminal tumors. The high-TIL subtype was also associated with lower ESR1/ESR2 expression ratio and increasing body mass index. The comparison of the immune profile in tumor and matched normal tissue suggested a tumor-derived activation of specific immune responses, which was only seen in high-TIL patients. Tumors in a second subtype were characterized by increased expression of interferon-stimulated genes and enrichment for TP53 somatic mutations. The presence of three immune subtypes within luminal BC was replicated in TCGA and KBC, although the pattern was more similar in Asian populations. The germline APOBEC3B deletion polymorphism, which is prevalent in East Asian populations and was previously linked to immune activation, was not associated with immune subtypes in our study. This result does not support the hypothesis that the germline APOBEC3B deletion polymorphism is the driving force for immune activation in breast tumors in Asian populations.ConclusionOur findings suggest that immune gene expression and associated genomic features could be useful to further stratify luminal BC beyond the current luminal A/B classification and a subset of luminal BC patients may benefit from checkpoint immunotherapy, at least in Asian populations.

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