Olema: This Phase I trial is seeking to determine the recommended dose, safety and tolerability of a new hormone therapy (OP-1250) in combination with targeted therapy (palbociclib) in people with advanced or metastatic HR+ and HER2- breast cancerA Phase 1 Dose Escalation and Dose Expansion Open-label, Multicenter, Study of OP-1250 in Combination with the CDK4/6 Inhibitor Palbociclib in Adult Subjects with Advanced or Metastatic HR-positive, HER2-negative Breast Cancer

Summary

This study consists of two parts: Part 1 Dose Escalation, and Part 2 Dose Expansion. In Part 1, participants will be allocated to receive different dosage levels of OP-1250 and this will be administered (orally) once daily in continuous 28-day cycles, in combination with oral palbociclib (125mg) once daily for 21 days in continuous 28-day cycles. Participants will continue to receive treatment at the assigned dose level, or at a reduced dose if required based on any toxicities that occur. Part 2 further explores the safety and Pharmacokinetics of OP-1250 in combination with Palbociclib and to determine the recommended Phase II dose (RP2D) of OP-1250.