Abstract 2935: Whole genome sequence of triple negative breast cancer (TNBC) tumors of African descent

Abstract

Abstract In the US, BC incidence has recently converged among self-reported European Americans (EA) and African Americans (AA), however BC mortality remains approximately 40% higher among AA compared to EA and other SRR groups. The initial divergence in mortality curves between these groups occurred at the advent of hormone receptor (HR) targeted treatment options, unmasking the heterogeneity of BC diagnoses. Here, we present Whole Genomes Sequencing of 30 Triple Negative Breast Cancers of African women presenting to the clinics in New York. These were collected as part of the ICSBCS cohort to identify ancestry related mutational signatures including complex structural variants which could help better explain etiology of cancer in these population and that we may leveraged for treatment or prognostic purposes. Somatic mutational landscape included higher frequency of TP53 (73%), BRCA1 (40%), ATK1 (37%), CDH1(37%), and CTCF (33%). We confirmed African ancestry of patients through ADMIXTURE and observed (>70%) African ancestry. Comparison between our cohort and TCGA BRCA showed higher tumor mutational burden in our cohort which could be accounted for by greater sensitivity in our updated sequencing technology and analysis pipelines. Mutational signature analysis showed cosmic Signature 3 suggesting evidence of defective homologous recombination and signature 16 with unknown etiology. In addition, we also observed evidence deletions and structural variants such as rigma, pyrgo and typhonas. Ongoing efforts are investigating complex structural variants in our cohort compared to similar populations from other studies while waiting on additional samples. Citation Format: Samuel Terkper Ahuno, Yajas Shah, Rachel Martini, Andrea Sboner, Nicolas Robine, Olivier Elemento, Marcin Imielinski, Lisa Newman, Melissa Davis. Whole genome sequence of triple negative breast cancer (TNBC) tumors of African descent [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2935.