All pts received prior endocrine therapy (range: 1-7 lines, 56.8% fulvestrant) and/or CDK4.6i(40.9%), chemotherapy(54.5%) in the advanced setting. Conclusions LX-039 was well tolerated with preliminary anti-tumor activity in ER+, HER2- ABC. RP2D was determined at 600 mg QD and a phase II trial is being planned.
We report herein its profound anti-tumor activity, desirable ER antagonistic characteristics combined with favorable pharmacokinetic and preliminary safety properties. LX-039 is currently in clinical trial (NCT04097756).