ONO-4578-06:Phase I Study of ONO-4578 and Letrozole Plus CDK4 /6 Inhibitors in Breast Cancer

ONO-4578-06: Phase I , Open-label, Non-blind, First-line Endocrine Therapy With ONO-4578 and Standard Treatment Letrozole and CDK4/6 Inhibitors (Palbociclib or Abemaciclib) in Patients With Metastatic or Recurrent Postmenopausal Hormone Receptor-positive HER2-negative Breast Cancer

This is a multicenter, open-label, non-controlled, phase I study to investigate the tolerability and safety of ONO-4578 used in combination with standard-of-care letrozole and a CDK4/6 inhibitor (palbociclib or Abemaciclib) as first-line endocrine therapy in postmenopausal patients with metastatic or recurrent hormone receptor-positive, HER2-negative breast cancer.

Inclusion Criteria:

1. Patients with postmenopausal metastatic or recurrent breast cancer
2. Patients with ECOG Performance Status 0 to 1
3. ER-positive, PgR-positive and HER2-negative patients

Exclusion Criteria:

1. Patients are unable to swallow oral medications
2. Patients with severe complication