Study of LEE011, BYL719 and Letrozole in Advanced ER+ Breast Cancer

Summary

The purpose of this trial is to inform the future clinical development of the two investigational agents in ER+ breast cancer, LEE011 (CDK4/6 inhibitor) and BYL719 (PI3K-alpha inhibitor). This is a multi-center, open-label Phase Ib study. The Phase Ib dose escalation will estimate the MTD and/or RP2D for three regimens: two double combinations, LEE011 with letrozole and BYL719 with letrozole, followed by triple combinations of LEE011 + BYL719 with letrozole (Arms 3 and 4). The Phase Ib dose escalation part will be followed by Phase Ib dose expansions to further characterize the safety, tolerability, PK and preliminary clinical anti-tumor activity of the combinations. Optional crossover for patients who have progressed while on dose escalation or dose expansion with doublet treatment on Arms 1 or 2 to be treated with the triplet combination (Arm 3) after the determination of the RP2D for Arm 3; is no longer permitted after protocol amendment 6. Approximately 270 adult women with ER+/HER2- locally advanced or metastatic breast cancer will be enrolled.

Timeline

Start

2013-10-22

Primary completion

2027-02-26

Completion

2027-02-26

Publications

• Ji Y, Wang C, Combes FP, Ho YY, Fasching PA, Untch M, Zarate JP, Crown J. Quantitative Pharmacology Justifying Ribociclib Dose in Early Breast Cancer. Clin Pharmacokinet. 2026 Jun 23. doi: 10.1007/s40262-026-01643-3. Online ahead of print.
• Ji Y, Yartsev V, Quinlan M, Serra P, Wang Y, Chakraborty A, Miller M. Justifying Ribociclib Dose in Patients with Advanced Breast Cancer with Renal Impairment Based on PK, Safety, and Efficacy Data: An Innovative Approach Integrating Data from a Dedicated Renal Impairment Study and Oncology Clinical Trials. Clin Pharmacokinet. 2023 Mar;62(3):493-504. doi: 10.1007/s40262-022-01206-2. Epub 2023 Feb 17.

Drugs

Indications