After 2 cycles, tumor response (≥30% reduction from baseline) by MRI was 90.5% and 40.0% (6 of 15) of patients who received only niraparib (2–6 cycles) had pathological complete response...In this pilot study, single-agent neoadjuvant niraparib demonstrated promising antitumor activity and high levels of tumor penetration in HER2-negative, BRCA-mut, localized BC.