The purpose of this research study is to determine the safety, tolerability and dose of Ribociclib when combined with adjuvant radiation in women with high-risk ER+ breast cancer.
Once enrolled on study, patients will begin treatment with Ribociclib 400 mg daily at the same time as they initiate standard of care adjuvant radiation therapy- 50 Gy in 25 fractions or 42.56 Gy in 16 fractions +/- 10 Gy boost including comprehensive nodal. Paitents will continue treatment with Ribociclib for up to 6 weeks.
ER and/or PR-positive (≥ 1% positivity as determined by local pathology laboratory), HER2-negative breast cancer with > 3 lymph nodes involved on sentinel lymph node biopsy (SLNB) or axillary lymph node dissection (ALND) OR have between 1-3 lymph nodes involved AND have T3 disease OR have between 1-3 lymph nodes involved and grade 3 breast cancer.
Age ≥ 18
Patients must have undergone gross total excision of all locoregional disease with negative margins (i.e. no tumor on ink). At least 21 days must elapse between surgical treatment for breast cancer and initiation of study treatment.
Patients must have completed chemotherapy (either in neoadjuvant or adjuvant setting). If received adjuvant chemotherapy, chemotherapy must have completed at least 21 days prior to initiation of study treatment.
Prior history of radiation therapy to the chest wall and/or regional nodes is not allowed (but prior radiation therapy to other sites is permissible).
Prior history of CDK4/6 inhibitor therapy.
Patients who are pregnant or breastfeeding.
Patient with distant metastases of breast cancer beyond regional lymph nodes and/or evidence of breast cancer recurrence prior to study enrollment.
Single group
Ribociclib
Drug400 mg daily with a possibly dose reduction to 200 mg daily if required
Postoperative Radiation Therapy
Radiation50 Gy in 25 fractions or 42.56 Gy in 16 fraction +/- 10 Gy boost including comprehensive nodal
Dose limiting toxicity (DLT) of ribociclib administered concurrently with adjuvant RT 1 month post last RT dose
Safety evaluations will be based on the incidence, intensity, and type of adverse events, and clinically significant changes in the patient's physical examination, vital signs, and clinical laboratory results. Safety variables will be tabulated and presented for all patients in the study. Exposure to study drug and reasons for discontinuation of study treatment will be tabulated.
Cumulative incidence of local failure (i.e. local recurrence events)
Calculation of follow-up time for all endpoints for patients will begin from the date of diagnosis until documentation of local or regional recurrence for local control, any failure (local, regional, or distant) or death for recurrence-free survival, and death for overall survival.
Local failure-free survival
The time from diagnosis date to the first of local or regional recurrence or death. Patients who are alive and free of local regional recurrence at lat follow up will be cencored at that date.
Recurrence-free survival
Date of diagnosis until documentation of death. Time-dependent and will be summarized using the Kaplan-Meier method or cumulative incidence method when competing events.
Overall survival
Overall survival as determined by the date of diagnosis until documentation of death. Time-dependent and will be summarized using the Kaplan-Meier method or cumulative incidence method when competing events.
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