Lerociclib plus fulvestrant in patients with HR+/HER2- locally advanced or metastatic breast cancer who have progressed on prior endocrine therapy: LEONARDA-1 a phase III randomized trial.

Lerociclib (GB491), a highly selective oral CDK4/6 inhibitor, has displayed anti-tumor activity and differentiated safety and tolerability profile in previous ph1/2 clinical trials. The LEONARDA-1, a randomized, double-blind, phase III study, was conducted to evaluate the efficacy and safety of lerociclib in HR+/HER2- locally advanced or metastatic breast cancer patients, who had relapsed or progressed on prior endocrine therapy. A total of 275 patients were randomized at 1:1 ratio to receive lerociclib (137 patients, 150 mg twice daily) or placebo (138 patients) plus fulvestrant. Progression-free survival (PFS) assessed by investigators was significantly improved in lerociclib arm versus placebo arm (11.07 vs 5.49 months; hazard ratio, 0.451, 95% CI: 0.311-0.656, P = 0.000016), meeting the pre-specified primary endpoint. The secondary endpoints included PFS assessed by Blinded Independent Central Review (BICR), objective response rate (ORR), duration of response (DOR), disease control rate (DCR), clinical benefit rate (CBR), overall survival (OS), safety and tolerability and pharmacokinetic profile. DOR is not reported, and OS data was immature at the data cut-off but unplanned ad hoc analysis is reported. These findings support lerociclib plus fulvestrant as a treatment option for patients with HR+/HER2- endocrine-resistant advanced breast cancer (ABC). (Funded by Genor Biopharma; LEONARDA-1 ClinicalTrials.gov identifier, NCT05054751.).