1. Identification of Somatically Acquired BRCA1/2 Mutations by cfDNA Analysis in Patients with Metastatic Breast Cancer
- Author
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Richard B. Lanman, Aditya Bardia, Brittany A. Reeves, Jochen K. Lennerz, Becky Nagy, Kristen M. Shannon, Daniel A. Haber, Beverly Moy, Shyamala Maheswaran, Brian Chirn, Gad Getz, Andrzej Niemierko, Laura Spring, Mehmet Toner, A. John Iafrate, Jerry Younger, Seth A. Wander, Michael S. Lawrence, Taronish D. Dubash, Douglas S. Micalizzi, Lee Zou, Erica Blouch, Whijae Roh, Neelima Vidula, Steven J. Isakoff, Giuliana Malvarosa, Antoine Simoneau, Leif W. Ellisen, and Dejan Juric
- Subjects
0301 basic medicine ,APOBEC ,Cancer Research ,endocrine system diseases ,Somatic cell ,business.industry ,medicine.disease ,Metastatic breast cancer ,Germline ,Olaparib ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,0302 clinical medicine ,Circulating tumor cell ,Oncology ,chemistry ,030220 oncology & carcinogenesis ,PARP inhibitor ,medicine ,Cancer research ,skin and connective tissue diseases ,business ,Genotyping - Abstract
Purpose: Plasma genotyping may identify mutations in potentially “actionable” cancer genes, such as BRCA1/2, but their clinical significance is not well-defined. We evaluated the characteristics of somatically acquired BRCA1/2 mutations in patients with metastatic breast cancer (MBC). Experimental Design: Patients with MBC undergoing routine cell-free DNA (cfDNA) next-generation sequencing (73-gene panel) before starting a new therapy were included. Somatic BRCA1/2 mutations were classified as known germline pathogenic mutations or novel variants, and linked to clinicopathologic characteristics. The effect of the PARP inhibitor, olaparib, was assessed in vitro, using cultured circulating tumor cells (CTCs) from a patient with a somatically acquired BRCA1 mutation and a second patient with an acquired BRCA2 mutation. Results: Among 215 patients with MBC, 29 (13.5%) had somatic cfDNA BRCA1/2 mutations [nine (4%) known germline pathogenic and rest (9%) novel variants]. Known germline pathogenic BRCA1/2 mutations were common in younger patients (P = 0.008), those with triple-negative disease (P = 0.022), and they were more likely to be protein-truncating alterations and be associated with TP53 mutations. Functional analysis of a CTC culture harboring a somatic BRCA1 mutation demonstrated high sensitivity to PARP inhibition, while another CTC culture harboring a somatic BRCA2 mutation showed no differential sensitivity. Across the entire cohort, APOBEC mutational signatures (COSMIC Signatures 2 and 13) and the “BRCA” mutational signature (COSMIC Signature 3) were present in BRCA1/2-mutant and wild-type cases, demonstrating the high mutational burden associated with advanced MBC. Conclusions: Somatic BRCA1/2 mutations are readily detectable in MBC by cfDNA analysis, and may be present as both known germline pathogenic and novel variants.
- Published
- 2020