Phase 2 trial of neoadjuvant tucidinostat plus exemestane for early-stage, HR-positive/HER2-negative breast cancer

Neoadjuvant endocrine therapy is a standard treatment for early-stage HR-positive/HER2-negative breast cancer (HR+/HER2- BC), but may lead to endocrine resistance. A phase 2 trial at Tianjin Medical University (China) evaluated addition of the oral HDAC inhibitor tucidinostat (aka chidamide) to neoadjuvant exemestane for stage II or III HR+/HER2- BC. Among 20 enrolled patients, 3 achieved preoperative endocrine prognostic index (PEPI) score 0. Nevertheless, the objective response rate was 50% and the disease control rate was 100%. All patients had at least one treatment-emergent adverse event. Five patients (25%) underwent breast conserving surgery, while 15 (75%) underwent modified radical mastectomy. The authors conclude that the neoadjuvant combination of tucidinostat plus exemestane was tolerated and induced promising responses in patients with stage II or III HR+/HER2- BC.