Carboplatin in BRCA1/2-mutated and triple-negative breast cancer BRCAness subgroups: the TNT Trial

Andrew Tutt, Holly Tovey, Maggie Chon U. Cheang, Sarah Kernaghan, Lucy Kilburn, Patrycja Gazinska, Julie Owen, Jacinta Abraham, Sophie Barrett, Peter Barrett-Lee, Robert Brown, Stephen Chan, Mitchell Dowsett, James M. Flanagan, Lisa Fox, Anita Grigoriadis, Alexander Gutin, Catherine Harper-Wynne, Matthew Q. Hatton, Katherine A. HoadleyJyoti Parikh, Peter Parker, Charles M. Perou, Rebecca Roylance, Vandna Shah, Adam Shaw, Ian E. Smith, Kirsten M. Timms, Andrew M. Wardley, Gregory Wilson, Cheryl Gillett, Jerry S. Lanchbury, Alan Ashworth, Nazneen Rahman, Mark Harries, Paul Ellis, Sarah E. Pinder, Judith M. Bliss, TNT Trialists

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Abstract

Germline mutations in BRCA1/2 predispose individuals to breast cancer (termed germline-mutated BRCA1/2 breast cancer, gBRCA-BC) by impairing homologous recombination (HR) and causing genomic instability. HR also repairs DNA lesions caused by platinum agents and PARP inhibitors. Triple-negative breast cancers (TNBCs) harbor subpopulations with BRCA1/2 mutations, hypothesized to be especially platinum-sensitive. Cancers in putative ‘BRCAness’ subgroups—tumors with BRCA1 methylation; low levels of BRCA1 mRNA (BRCA1 mRNA-low); or mutational signatures for HR deficiency and those with basal phenotypes—may also be sensitive to platinum. We assessed the efficacy of carboplatin and another mechanistically distinct therapy, docetaxel, in a phase 3 trial in subjects with unselected advanced TNBC. A prespecified protocol enabled biomarker–treatment interaction analyses in gBRCA-BC and BRCAness subgroups. The primary endpoint was objective response rate (ORR). In the unselected population (376 subjects; 188 carboplatin, 188 docetaxel), carboplatin was not more active than docetaxel (ORR, 31.4% versus 34.0%, respectively; P = 0.66). In contrast, in subjects with gBRCA-BC, carboplatin had double the ORR of docetaxel (68% versus 33%, respectively; biomarker, treatment interaction P = 0.01). Such benefit was not observed for subjects with BRCA1 methylation, BRCA1 mRNA-low tumors or a high score in a Myriad HRD assay. Significant interaction between treatment and the basal-like subtype was driven by high docetaxel response in the nonbasal subgroup. We conclude that patients with advanced TNBC benefit from characterization of BRCA1/2 mutations, but not BRCA1 methylation or Myriad HRD analyses, to inform choices on platinum-based chemotherapy. Additionally, gene expression analysis of basal-like cancers may also influence treatment selection.
Original languageEnglish
Pages (from-to)628–637
JournalNature Medicine
Volume24
Issue number5
Early online date30 Apr 2018
DOIs
Publication statusPublished - 1 May 2018

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