Neoadjuvant tucidinostat combined with chemotherapy for hormone receptor-positive, HER2-negative breast cancer.

Abstract

e12617 Background: Both neoadjuvant chemotherapy and endocrine therapy only result in trivial pathological complete response rates and moderate objective response rate (ORR) in hormone receptor (HR)-positive, HER2-negative breast cancer, more promising alternatives are urgently needed. Tucidinostat is an oral subtype-selective histone deacetylase inhibitor that has shown efficacy and safety when used in combination with exemestane in patients with advanced HR+ breast cancer. This MUKDEN 05 study aimed to assess the efficacy and toxicity of the combination of tucidinostat and EC-T as a neoadjuvant strategy in patients with HR+/HER2-, stage II-III breast cancer. Methods: This study is a multicenter, single-arm, phase II study. Eligible patients received 20 mg tucidinostat orally twice a week (on days 1, 4, 8, and 11), 2 weeks on, 1 week off. The dose and administration schedule of EC-T were as follows: 4 cycles of epirubicin 90 mg/m2 and cyclophosphamide 600 mg/m2 every 3 weeks, followed by 4 cycles of docetaxel 100 mg/m2 every 3 weeks. The primary endpoint was the proportion of residual cancer burden (RCB) 0-I. Key secondary endpoints included pathological complete response (pCR), objective response rate (ORR), and safety. Results: Between May 2022 and August 2022, a total of 35 patients were enrolled. 27 patients were pathologically evaluable. The remaining 8 patients have completed neoadjuvant treatment and wait for operation. The ratio of RCB 0-I was 37% (95% CI, 23.2-53.7%). ORR was 86% (95% CI, 70.6-93.7%). Four (15%; 95% CI, 5.91-32.5%) patients achieved bpCR, and one (4%; 95% CI, 0.67-18.3%) patients achieved tpCR. Most adverse events (AEs) were grade 1 or 2. Grade 3/4 AEs included neutropenia (21.1%), and thrombocytopenia (15.8%). Conclusions: The combination of Tucidinostat and EC-T had an acceptable safety profile and encouraging clinical responses, offering a neoadjuvant treatment option for patients with early HR+/HER2- breast cancer. Further research is required to validate these findings. Clinical trial information: NCT05400993 .