- Adding tucidinostat (previously called chidamide) to exemestane prolonged PFS by 25% in a phase 3 trial of postmenopausal hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer.
- Most common toxicities of tucidinostat are hematologic.
Why this matters
- First trial of a histone deacetylase inhibitor in breast cancer.
- Findings are promising enough to lead to a new treatment option.
- Randomized, double-blind, 22-center, Chinese phase 3 ACE trial of 365 women with disease relapse or progression after ≥1 endocrine therapy
- Patients received 25 mg oral exemestane daily, with tucidinostat (30 mg orally twice weekly) or placebo.
- Funding: Chipscreen Biosciences.
- Median follow-up, 13.9 months.
- Adding tucidinostat vs placebo resulted in 25% longer PFS (7.4 [95% CI, 5.5-9.2] months vs 3.8 [95% CI, 3.7-5.5] months); HR, 0.75; P=.033.
- Add-on tucidinostat yielded greater clinical benefit (objective response or stable disease lasting ≥25 weeks; 47% [95% CI, 41%-53%] vs 36% [95% CI, 27%-44%]; P=.034).
- Tucidinostat was associated with a higher proportion of grade 3-4 hematologic toxicity:
- Neutropenia (51% vs 2% in placebo group).
- Thrombocytopenia (27% vs 2%).
- Leucopenia (19% vs 2%).
- Study limited to Chinese women.