Tucidinostat Plus Exemestane as a Neoadjuvant in Early-Stage, Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer

Background To assess the efficacy and safety of tucidinostat plus exemestane as a neoadjuvant strategy in early-stage breast cancer.Methods This prospective, open-label, single-arm phase II trial enrolled patients with stage II-III breast cancer with hormone receptor-positive and human epidermal growth factor receptor 2 (HER2)-negative. Eligible patients received tucidinostat plus exemestane, and then breast-conserving surgery (BCS) or modified radical mastectomy.Results Among 20 enrolled patients, 3 of them achieved preoperative endocrine prognostic index (PEPI) score of 0. Additionally, complete cell cycle arrest was observed in 7, radiologic objective response rate in 10, and disease control rate in 20 patients, pathological complete response in 1 patient, and 5 patients performed BCS. Ki67 suppression from baseline to surgery was observed in 17 of patients, with the Ki67 change ratio of -73.5%. Treatment-emergent adverse event included neutropenia, leukopenia, thrombocytopenia, lymphopenia, hypoalbuminemia, aspartate aminotransferase elevation, glutamyl transpeptidase elevation, anemia, and alanine aminotransferase elevation.Conclusions Despite the rate of PEPI score 0 was not high, tucidinostat plus exemestane as a neoadjuvant therapy might be well tolerated and showed promising clinical responses in patients with early hormone receptor-positive, HER2-negative breast cancer. To clarify the safety and efficacy of this strategy, further investigation is warranted.Clinical Trial Registration ChiCTR2100046678. This study assessed the efficacy and safety of tucidinostat plus exemestane as a neoadjuvant strategy in early-stage breast cancer.