Neoadjuvant Chemotherapy With Anthracycline-Based Regimen for BRCAness Tumors in Triple-Negative Breast Cancer.

Background: A subgroup of triple-negative breast cancer (TNBC) shows impaired BRCA1 function owing to causes other than mutation, which is called "BRCAness." DNA-damaging agents are known to have more efficacy in BRCA1-mutant tumors than mitotic poisons. We conducted a prospective single-arm clinical trial of neoadjuvant chemotherapy (NAC) using an anthracycline-based regimen without taxanes for BRCAness TNBCs.
Materials and Methods: BRCAness was examined using the multiplex ligation-dependent probe amplification (MLPA) method in TNBC cases. For BRCAness cases, NAC was performed with anthracycline-based regimens without additional taxanes.
Results: A total of 30 patients with TNBC were enrolled. MLPA was successfully performed in 25 patients. Eighteen patients (72%) showed BRCAness. Twenty-three patients received NAC as per the protocol. On analysis, the clinical response rate (complete response plus partial response) was 76.4%, and the pathological complete response rate was 35.3%.
Conclusions: The interim analysis revealed that the pathological complete response rate was lower than estimated. Therefore, BRCAness by MLPA was not sufficient to predict the therapeutic response to anthracycline-based regimens in TNBC.
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