Multicenter phase 3 trial of tibremciclib plus fulvestrant or placebo plus fulvestrant for HR-positive, HER2-negative advanced breast cancer after endocrine therapy

Tibremciclib is a novel CDK 4/6 inhibitor. The phase 3 TIFFANY trial, at 69 centers in China, compared tibremciclib plus fulvestrant versus placebo plus fulvestrant among patients with HR-positive, HER2-negative advanced breast cancer (aBC) who experienced progression while receiving prior endocrine therapy. In this trial of 274 patients, the median progression-free survival was 16.5 months with tibremciclib plus fulvestrant versus 5.6 months with placebo plus fulvestrant (HR 0.37; p<0.001). The combination of tibremciclib plus fulvestrant had a manageable safety profile. The authors conclude that addition of tibremciclib to fulvestrant resulted in statistically significant and clinically meaningful improvement in PFS among patients with HR+, HER2- aBC, with a manageable safety profile (visual abstract).