Stereotactic Radiosurgery With Abemaciclib, Ribociclib, or Palbociclib in Treating Patients With Hormone Receptor Positive Breast Cancer With Brain Metastases

PRIMARY OBJECTIVE: I. Prospectively evaluate safety and toxicity of the combination of radiosurgery (SRS) and concurrent CDK 4/6 inhibitors (CDKi) for hormone receptor positive (HR+) breast cancer patients. SECONDARY OBJECTIVES: I. Evaluate late toxicity (after 3 months) following SRS and concurrent CDKi. II. Evaluate local control efficacy with combination therapy of SRS and concurrent CDKi. III. Assess quality of life and neurologic functional outcomes following treatment using standardized questionnaire (Functional Assessment of Cancer Therapy-Brain \[FACT-Br\]). IV. Analyze overall survival. OUTLINE: Patients are assigned to 1 of 3 groups. GROUP I: Beginning within 2 weeks prior to stereotactic radiosurgery, patients receive abemaciclib orally (PO) twice daily (BID). Treatment continues in the absence of disease progression or unacceptable toxicity. GROUP II: Beginning within 2 weeks prior to stereotactic radiosurgery, patients receive ribociclib PO once daily (QD) on days 1-21. Treatment continues in the absence of disease progression or unacceptable toxicity. GROUP III: Beginning within 2 weeks prior to stereotactic radiosurgery, patients receive palbociclib PO QD on days 1-21. Treatment continues in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up at 30 days, 4-6 weeks post stereotactic radiosurgery, and then every 3 months for up to 1 year.