149P HER2-low status and response to neoadjuvant chemotherapy in early breast cancer

Some recent evidence has suggested that HER2-low breast cancers (BC) are distinct entities. The prognostic impact of low expression HER-2 not yet well defined, and inconsistent results were reported. This study aims to evaluate the status on response neoadjuvant chemotherapy (NACT). We retrospectively analyzed HER2-negative BC patients treated with NACT from 2017 2022 in a single academic center. was defined by IHC +1 or +2 ISH non-amplified, HER2-zero 0. primary objective compare pathological complete (pCR) rates between populations. 101 identified. 70 (69.3%) had hormone receptor (HR) positivity, 31 (30.7%) TNBC. Overall HER2-low. Among HR-positive patients, 25 (35.7%) HER2-low, while only 6 (19.3%) her2 TNBC group,There no significant differences median age, Ki67 score, histology, menopausal status, histologic grade, T stage groups. There also ER level tumors; 75% for tumors 90% (p = 0.028). Overall, pCR achieved 24 (23.7%) patients. 21 (30%) 3 (9.7%) group (p=0.027). In subtype, there still statistically two 15 group; among these, 13 (87%) tumors, 2 (13%) them 0.041). 9 pCR; 8 (89%) HER2 zero 1 (11%) but statistical significance 0.642). Our show have different NACT. Both overall subgroup, significantly lower rates. Because cross-talk HR signaling signaling, may be responsible treatment resistance BC.