A Phase 1 Study of Oral OP-1250 in Combination With Palbociclib in HR+/HER2- Breast Cancer Patients

This is an open-label, Phase 1b dose escalation and expansion study to determine the maximum tolerated dose (MTD) of OP-1250 in combination with palbociclib (Ibrance®️, Pfizer Inc.). Purpose of study is to evaluate the safety and pharmacokinetic (PK) profile, and estimate the preliminary anti-tumor activity of the combination in adult subjects with hormone receptor-positive (ER+ / HER2-) advanced or metastatic breast cancer (MBC).

Inclusion Criteria: * Confirmed and evaluable locally advanced or metastatic breast cancer * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Must not have received prior oral endocrine or targeted therapy ≤ 2 weeks prior to first dose * Must not have received prior chemotherapy, antibody therapy, or investigational therapy ≤ 4 weeks prior to the first dose * Prior radiotherapy must have been completed 2 weeks prior to first dose * Adequate safety laboratory tests * Willingness to use effective contraception Exclusion Criteria: * Gastrointestinal disease * Significant hepatic disease * Significant cardiovascular disease * Significant ECG abnormalities * History of pulmonary embolism or high risk of thrombosis * Known HIV infection * Active infection (requiring antimicrobial therapy) * Pregnant