The purpose of this study is to learn about the safety and effects of the study medicine called vepdegestrant. The safety and effects of vepdegestrant will be see when given with other medicines. Vepdegestrant is studied to see if it can be a possible treatment for advanced metastatic breast cancer. This type of cancer would have spread from where it started (breast) to other parts of the body and would be tough to treat. The study is seeking for participants who have breast cancer that: * is hard to treat (advanced) and may have spread to other organs (metastatic). is sensitive to hormonal therapy (it is called estrogen receptor positive). * is no longer responding to treatments taken before starting this study. This study is divided into separate sub-studies. For Sub-Study C: All the participants will receive vepdegestrant and a medicine called samuraciclib. Vepdegestrant and samuraciclib will be taken once in a day by mouth. The medicines will be taken at home. The experience of people receiving the study medicines will be studied. This will help see if the study medicine is safe and effective. Participant will continue to take vepdegestrant and samuraciclib until: * their cancer is no longer responding, or * side effects become too severe. They will have visits at the study clinic about every 4 weeks.
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Phase 1b: Number of Participants With Dose Limiting Toxicities
Timeframe: 28 days
Drug Drug Interaction: To evaluate the effect of samuraciclib on PK of ARV 471.
Timeframe: From the start of Lead-in period (maximum 13 days) to the end of cycle 1 (at least 28 days)
Drug Drug Interaction: To evaluate the effect of samuraciclib on PK of ARV 471.
Timeframe: From the start of Lead-in period (maximum 13 days) to the end of cycle 1 (at least 28 days)
Phase 2: Percentage of Participants With Objective Response by investigator assessment
Timeframe: Up to approximately 1 year
Drug Drug Interaction: • To evaluate the effect of ARV 471 on PK of samuraciclib.
Timeframe: From the start of Lead-in period (maximum 13 days) to the end of cycle 1 (at least 28 days))
Drug Drug Interaction: • To evaluate the effect of ARV 471 on PK of samuraciclib.
Timeframe: From the start of Lead-in period (maximum 13 days) to the end of cycle 1 (at least 28 days))