HDAC inhibitor Tucidinostat plus exemestane as neoadjuvant therapy in patients with hormone receptor positive, HER2 negative breast cancer.

Abstract

e12623 Background: Tucidinostat (formerly known as chidamide) is an oral subtype-selective histone deacetylase (HDAC) inhibitor with demonstrated efficacy and safety in combination with exemestane in postmenopausal patients with advanced, hormone receptor-positive breast cancer. The aim of this study was to evaluate the efficacy of tucidinostat combined with exemestane as neoadjuvant strategy in hormone receptor-positive early breast cancer patients. Methods: The study (ChiCTR2100046678) is a single-center, prospective, open-labeled, single-arm phase II study. Patients with HR-positive, HER2-negative, and node-positive, stage II–III breast cancer were enrolled at Tianjin Medical University Cancer Institute and Hospital. Eligible patients received 30 mg oral tucidinostat twice weekly in combination with 25 mg oral exemestane daily for up to a total of 24 weeks. The primary endpoint was to determine percent of pts who achieve a PEPI score of 0. The secondary endpoints were to analyze the the pathological complete remission (pCR) rate, complete cell cycle arrest (CCCA, defined as Ki67<2.7%), objective response rate (ORR), disease control rate (DCR) and event free survival (EFS), and overall survival (OS) as well as the safety and tolerability. Results: Patient enrollment initiated in Jan. 2021 and ended in Nov. 2021. Of the 20 pts enrolled, 20 were treated and radiologically evaluable for response. The ORR was 40% with CR 5% (n=1) and PR 35% (n=7). The DCR was 100%. Four patients were still on wait lists for surgery. Of the 16 pts with surgery, one case achieved pCR. The follow-up remains ongoing and updated results will be presented thereafter. Most adverse events (AEs) were grade 1 or 2. Grade 3 AEs included neutropenia (11.8%), thrombocytopenia (5.9%) and lung infection (5.9%), respectively. Conclusions: The combination of Tucidinostat and exemestane was well tolerated with encouraging clinical responses in early hormone receptor positive, HER2 negative breast cancer. Further investigation is warranted. Clinical trial information: ChiCTR2100046678.