Comprehensive characterization of pre- and post-treatment samples of breast cancer reveal potential mechanisms of chemotherapy resistance

When locally advanced breast cancer is treated with neoadjuvant chemotherapy, the recurrence risk is significantly higher if no complete pathologic response is achieved. Identification of the underlying resistance mechanisms is essential to select treatments with maximal efficacy and minimal toxicity. Here we employed gene expression profiles derived from 317 HER2-negative treatment-naïve breast cancer biopsies of patients who underwent neoadjuvant chemotherapy, deep whole exome and RNA-sequencing profiles of 22 matched pre- and post-treatment tumors, and treatment outcome data to identify biomarkers of response and resistance mechanisms. Molecular profiling of treatment-naïve breast cancer samples revealed that expression levels of proliferation, immune response and extracellular matrix (ECM) organization combined predict response to chemotherapy. Triple negative patients with high proliferation, high immune response and low ECM expression had a significantly better treatment response and survival benefit (HR 0.29, 95% CI 0.10-0.85; p=0.02), while in ER+ patients the opposite was seen (HR 4.73, 95% CI 1.51-14.8; 0=0.008). The characterization of paired pre-and post-treatment samples revealed that aberrations of known cancer genes were either only present in the pre-treatment sample (CDKN1B) or in the post-treatment sample(TP53, APC, CTNNB1). Proliferation-associated genes were frequently down-regulated in post-treatment ER+ tumors, but not in triple negative tumors. Genes involved in ECM were upregulated in the majority of post-chemotherapy samples. Genomic and transcriptomic differences between pre- and post-chemotherapy samples are common and may reveal potential mechanisms of therapy resistance. Our results show a wide range of distinct, but related mechanisms, with a prominent role for proliferation- and ECM-related genes.

Type: Other
Archiver: European Genome-Phenome Archive (EGA)

3 Datasets 1 Publication

Click on a Dataset ID in the table below to learn more, and to find out who to contact about access to these data

Dataset ID	Description	Technology	Samples
EGAD00001008421	This dataset contains RNAseq data of 20 paired pre-post neoadjuvant chemotherapy breast cancer samples. In total the set contains n=20 biopsies, n=20 surgery specimens. Each sample has 2 fastq files, so n=80 fastq files are uploaded in total.	Illumina HiSeq 2000	40
EGAD00001008433	This dataset contains RNAseq data of n=87 pre-treatment biopsies of triple negative and luminal- type breast cancer patients, all scheduled to receive neoadjuvant chemotherapy. Gene expression data is linked with treatment response and survival.	Illumina HiSeq 2000	1
EGAD00001008442	This dataset contains whole exome sequencing data (WES) of 20 paired pre- and post neoadjuvant chemotherapy breast cancer samples. From every patient a pre-treatment biopsy (B) and a post-treatment surgery (S) specimen has been sequenced. From most patients a paired normal blood sample (N) has been sequenced as a reference control.	Illumina HiSeq 2500	1

Publications	Citations
Comprehensive characterization of pre- and post-treatment samples of breast cancer reveal potential mechanisms of chemotherapy resistance. Hoogstraat M, Lips EH, Mayayo-Peralta I, Mulder L, Kristel P, van der Heijden I, Annunziato S, van Seijen M, Nederlof PM, Sonke GS, Zwart W, Wesseling J, Wessels LFA. NPJ Breast Cancer 8: 2022 60	7