A Phase 1b Open-Label Multicenter Study of OP-1250 in Combination with the CDK4/6 Inhibitor Ribociclib or with the PI3K Inhibitor Alpelisib in Adult Subjects with Advanced and/or Metastatic HR Positive, HER2 Negative Breast Cancer

Participants will be invited to take part in this clinical research study if they have been treated for hormone receptor (HR)-positive and human epidermal growth factor receptor 2 negative (HER2)-negative breast cancer and have not responded to conventional therapy or the cancer has come back. This study involves research and is being conducted to determine the safety and efficacy of the investigational study drug, OP-1250. The main purpose of this study is to look at how safe and well tolerated the study drug is in combination with ribociclib (Group 1) or alpelisib (Group 2), the levels of the study drug and ribociclib or alpelisib in your blood, and how your body and your cancer respond.