Study on Adding Palbociclib to Standard Hormone Therapy for Early HR+/HER2- Breast Cancer

Inclusion Criteria

• Must provide signed consent before participating.
• Age 18 or older.
• Women (pre- and postmenopausal) or men with Stage II or Stage III early breast cancer.
• Can have multiple or bilateral breast tumors if all are ER+ and/or PR+ and HER2-.
• Must have confirmed ER+ and/or PR+, HER2- breast cancer.
• Must have had surgery to remove the breast cancer.
• Must provide a tumor tissue sample before starting the study.
• Must be in good general health (ECOG status 0-1).
• Must be able to take oral medication.
• Premenopausal women must have a negative pregnancy test within 14 days before starting.
• Must have recovered from any side effects of previous cancer treatments.
• Must be starting or have started hormone therapy.
• Must meet specific blood count and liver function test requirements.

Exclusion Criteria

• Cannot be taking other experimental treatments.
• Cannot have used any CDK inhibitors before.
• Cannot have Stage I or Stage IV breast cancer.
• Cannot have allergies to similar drugs as palbociclib.
• Cannot be taking certain medications that affect liver enzymes within 7 days before starting.
• Cannot have uncontrolled health issues that would interfere with the study.
• Cannot be pregnant or not have a recent negative pregnancy test.
• Cannot have a history of other cancers.
• Cannot have used hormone therapy within 5 years before the current cancer diagnosis.
• Cannot be on antiretroviral therapy.
• Cannot have significant liver disease.
• Cannot be using hormone therapy, except for certain topical treatments.