Ribociclib and Aromatase Inhibitor in Treating Older Participants With Hormone Receptor Positive Metastatic Breast Cancer

Inclusion Criteria

• Patient has signed the informed consent (ICF) prior to any study procedures being performed and is able to comply with protocol requirements
• Must be able to swallow ribociclib
• Age: >= 70 years at time of enrollment >= 70 to = 75 years
• NOTE: A minimum of 20 participants must be >= 75 years. The remaining 20 participants may be >= 70 to = 75 years
• Subjects must be able to communicate with the investigator and comply with the requirements of the study procedures
• Patient has a histologically and/or cytologically confirmed diagnosis of estrogen-receptor positive and/or progesterone receptor positive breast cancer, HER2-negative breast cancer defined as a negative in situ hybridization test or an IHC status of 0, 1+ or 2+, and metastatic breast cancer
• First or second line endocrine therapy for metastatic disease. One prior line of chemotherapy for metastatic disease is allowed
• Absolute neutrophil count >= 1.5 x 10^9 /L, at screening
• Platelets >= 100 x 10^9 /L, at screening
• Hemoglobin >= 9.0 g/dL, at screening
• Patient must have the following laboratory values within normal limits or corrected to within normal limits with supplement before the first dose of study medication:
• Sodium
• Potassium
• Magnesium
• Total calcium (corrected for serum albumin)
• Phosphorous
• Serum creatinine = 50 mL/min, at screening
• In the absence of liver metastases, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) 160 mmHg or < 90 mmHg at screening
• Patient is currently receiving any of the following medications and cannot be discontinued 7 days prior to starting study drug:
• Known strong inducers or inhibitors of CYP3A4/5, including grapefruit, grapefruit hybrids, pummelos, star-fruit, and Seville oranges
• That have a narrow therapeutic window and are predominantly metabolized through CYP3A4/5
• Herbal preparations/medications, dietary supplements
• Warfarin or other coumadin-derived anticoagulant for treatment, prophylaxis or otherwise. Therapy with heparin, low molecular weight heparin (LMWH), newer anticoagulation agents such as direct factor Xa inhibitors, or fondaparinux is allowed
• Patient is currently receiving or has received systemic corticosteroids =< 2 weeks prior to starting study drug, or who have not fully recovered from side effects of such treatment
• The following uses of corticosteroids are permitted: single doses, topical applications (e.g., for rash), inhaled sprays (e.g., for obstructive airways diseases), eye drops or local injections (e.g., intra-articular)
• Patient has impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of the study drugs (e.g., ulcerative diseases, uncontrolled nausea, vomiting, diarrhea, malabsorption syndrome, or small bowel resection)
• Patient has any other concurrent severe and/or uncontrolled medical condition that would, in the investigator's judgment, cause unacceptable safety risks, contraindicate patient participation in the clinical study or compromise compliance with the protocol (e.g. chronic pancreatitis, chronic active hepatitis, active untreated or uncontrolled fungal, bacterial or viral infections, etc.)
• Participation in a prior investigational study within 30 days prior to enrollment or within 5 half-lives of the investigational product, whichever is longer
• Patient has had major surgery and/or radiotherapy within 14 days prior to starting study drug or has not recovered from major side effects (tumor biopsy is not considered as major surgery)
• Patient with a Child-Pugh score B or C
• Patient has not recovered from the acute effects of prior systemic therapy (until the toxicity resolves to either baseline or at least grade 1) except for residual alopecia or peripheral neuropathy
• Patient has a history of non-compliance to medical regimen or inability to grant consent
• Sexually active males unless they use a condom during intercourse while taking the drug and for 21 da