Genomic characterization of tumor mutational burden-high breast carcinomas

Abstract Tumor mutational burden (TMB) has emerged as a potential surrogate for neoantigen load and an indicator of immune checkpoint (IC)-blockade response; however, its precise significance in breast cancer (BC) is not fully understood. Here, we comprehensively characterized the genomic repertoire...

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Main Authors: Theodore Vougiouklakis, Chad Vanderbilt, Satshil Rana, Abhinita Mohanty, Fresia Pareja, Edi Brogi, Christopher Schwartz, Maria E. Arcila, Marc Ladanyi, Hanna Y. Wen, Dara S. Ross
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:npj Precision Oncology
Online Access:https://doi.org/10.1038/s41698-025-01045-x
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Summary:Abstract Tumor mutational burden (TMB) has emerged as a potential surrogate for neoantigen load and an indicator of immune checkpoint (IC)-blockade response; however, its precise significance in breast cancer (BC) is not fully understood. Here, we comprehensively characterized the genomic repertoire of BCs with a TMB ≥ 10 mut/Mb (TMB-high [n = 527]) to identify putative predictors of importance. The predominant mutational signature was apolipoprotein B mRNA-editing enzyme catalytic polypeptide (APOBEC) in 64.7% of tumors. TMB-high BCs were enriched in KMT2C, ARID1A, PTEN, NF1, and RB1 alterations, which are associated with APOBEC mutagenesis. Further identified were loss-of-function ARID1A and PTEN alterations, which are linked to immune cell exclusion. ESR1 p.E380Q prevailed among all ESR1 hotspot mutations, supporting APOBEC-mediated effects. Finally, mutations in DNA damage response and repair genes were seen at a higher frequency than in non-TMB-high BCs. These findings provide justification for exploring combined pharmacologic inhibition to improve IC-based efficacy.
ISSN:2397-768X