Triple-negative breast cancer (TNBC) represents approximately 15-20% of all breast cancer types. It is more common among African American (AA) and Hispanic-Latina (HL) women and has more aggressive course. The biology of TNBC in HL women has been poorly characterized, but some data suggest that molecular drivers of breast cancer might be different. Chemotherapy remains the only option for those patients. There is no clinical tool to help medical oncologist with the decision about appropriate individual chemotherapy, as well as no way to predict long-term outcomes. The aim of the study was to characterize individual patient gene expression profiles and to identify the relationship with clinical outcomes.Patients and Methods: From 2012-2019, we collected formalin-fixed paraffin-embedded tumors (FFPE) from women with TNBC. All specimens were carefully examined by pathologists for adequacy and for a hormonal status. We analyzed gene mutation profiles of collected tumors and associated results with individual patient’s clinical history and outcomes.Results: Of 25 patients with TNBC, 24 (96%) identified as HL, one patient as NHL. Twenty-one (84%) had stage III/IV disease, and four (16%) had stage II at the diagnosis. Most commonly mutated genes were: TP53, Notch, AKT, MEP3K, PIK3CA and EGFR. Compared to other international cancer databases mostly included NHW, AA and Asian women, our study demonstrated statistically significant higher frequencies of those among HL women. With TNBC. Also a worse clinical course was among those patients whose tumor had mutations in Notch and PIK3CA. Conclusion: In conclusion, this study is the first to identify the most common genetic alterations among HL women with TNBC. Our data strongly support the notion that molecular drivers of breast cancer could be different in HL women. Therefore, a deeper understanding of the biological mechanisms behind Notch, PIK3CA mutation, might lead to a new treatment approach.

Citation Format: Alexander Philipovskiy, Alok Dwivedi, Roberto Gamez, Richard McCallum, Zeina Nahleh, Renato Aguilera, Sumit Gaur. Association between tumor mutation profile and clinical outcomes among Hispanic Latina women with triple-negative breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS18-45.