Molecular Subtyping of Triple-negative Breast Cancer and African Ancestry-related Immunogenicity

This study seeks to characterize the mRNA profile of TNBC in Nigeria and compare to a reference population in Nova Scotia. Insight into the unique tumor-immune profile of TNBC in Nigeria and the link between the West African-linked Duffy-antigen receptor for chemokines (DARC) and TNBC subtype will be explored for the first time.

Fresh frozen TNBC tissue from the African Research Group for Oncology (ARGO) and Dalhousie/NSHA breast cancer biobanks' will be processing and analyzed by the Genomics Core Facility at Dalhousie University. Clinical data is prospectively collected with specimen acquisition in the ARGO biobank. For the Dalhousie /NSHA biobank, clinical data will be retrospectively gathered from the medical record and migrated to an electronic database for prospective collection during the course of the study. Both cohorts of specimens will be run through DNA and whole transcriptome (mRNA) sequencing on the TSO500 platform (Illumina Ulc.). The tumor-immune microenvironment will be compared between cohorts and by mRNA cluster using the transcriptional signatures for 22 leukocyte populations and immune-regulating proteins CTLA-4 and PD-L1. Finally, tumor expression of DARC will be generated from the transcriptome data that will allow for an assessment of the relationship between DARC expression, TNBC mRNA clusters, and sociodemographic variables (i.e. race/ancestry, gender). Whole transcriptome data from The Cancer Genome Atlas will be pulled as the third cohort, including 55 TNBC specimens from African Americans.