BRCA Mutation Status in Triple-Negative Breast Cancer Patients Treated with Neoadjuvant Chemotherapy: A Pivotal Role for Treatment Decision-Making

SIMPLE SUMMARY: In this retrospective observational study, we evaluated data from patients with triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy (NACT) in order to better define the impact of germline BRCA1/2 (gBRCA1/2) mutation status on outcomes in this patient population. Our results show that patients with BRCA1/2 mutation had a higher pathologic complete response (pCR) rate than non-mutated patients; nevertheless, the benefit was confirmed only in the subset of patients who received a platinum-based NACT. Furthermore, pCR was associated with improved Event Free Survival (EFS) and Overall Survival (OS), regardless of BRCA1/2 mutation status and type of NACT received. Long-term follow-up analyses are needed to further define the impact of gBRCA mutation status in patients with early-TNBC. ABSTRACT: Triple-negative breast cancer (TNBC) is characterized by earlier recurrence and shorter survival compared with other types of breast cancer. Moreover, approximately 15 to 25% of all TNBC patients harbor germline BRCA (gBRCA) 1/2 mutations, which confer a more aggressive phenotype. However, TNBC seems to be particularly sensitive to chemotherapy, the so-called ‘triple negative paradox’. Therefore, Neoadjuvant chemotherapy (NACT) is currently considered the preferred approach for early-stage TNBC. BRCA status has also been studied as a predictive biomarker of response to platinum compounds. Although several randomized trials investigated the addition of carboplatin to standard NACT in early-stage TNBC, the role of BRCA status remains unclear. In this retrospective analysis, we evaluated data from 136 consecutive patients with Stage I-III TNBC who received standard NACT with or without the addition of carboplatin, in order to define clinical features and outcomes in BRCA 1/2 mutation carriers and non-carrier controls. Between January 2013 and February 2021, 67 (51.3%) out of 136 patients received a standard anthracyclines/taxane regimen and 69 (50.7%) patients received a platinum-containing chemotherapy regimen. Deleterious germline BRCA1 or BRCA2 mutations were identified in 39 (28.7%) patients. Overall, patients with deleterious gBRCA1/2 mutation have significantly higher pCR rate than non-carrier patients (23 [59%] of 39 vs. 33 [34%] of 97; p = 0.008). The benefit of harboring a gBRCA mutation was confirmed only in the subset of patients who received a platinum-based NACT (17 [65.4%] of 26 vs. 13 [30.2%] of 43; p = 0.005) while no differences were found in the platinum-free subgroup. Patients who achieved pCR after NACT had significantly better EFS (OR 4.5; 95% CI 1.9–10.7; p = 0.001) and OS (OR 3.3; 95% CI 1.3–8.9; p = 0.01) than patients who did not, regardless of BRCA1/2 mutation status and type of NACT received. Our results based on real-world evidence show that TNBC patients with the gBRCA1/2 mutation who received platinum-based NACT have a higher pCR rate than non-carrier patients, supporting the use of this chemotherapy regimen in this patient population. Long-term follow-up analyses are needed to further define the role of gBRCA mutation status on clinical outcomes in patients with early-TNBC.