BACKGROUND: Cyclin-dependent kinase 4 and 6 inhibitors (CDKIs) are effective and safe against advanced and metastatic breast cancer
however, limited information is available for older patients. We conducted an analysis of real-world data pertaining to the safety of older patients using the Adverse Event Reporting System (FAERS) database of the FDA. RESEARCH DESIGN AND METHODS: We performed a disproportionality analysis to evaluate CDKI-related adverse events (AEs) in older adults administered abemaciclib, palbociclib, and ribociclib. RESULTS: Data were from 2132, 36916, and 4328 case reports on abemaciclib, palbociclib, and ribociclib in older patients, respectively. Disproportionality analysis revealed 242, 295, and 439 drug-AE signals. The numbers of system organ classes (SOC) for abemaciclib, palbociclib, and ribociclib were 25, 27, and 26, respectively. We found several expected AE signals consistent with those in the drug instructions, such as nausea, neutropenia, and fatigue, for all CDKIs. Interstitial lung disease, thromboembolic events, and cardiac toxicity were also noteworthy. Unexpected AE signals, such as acute kidney injury, atrial fibrillation, and memory impairment associated with abemaciclib, ribociclib, and palbociclib, respectively, were identified. CONCLUSION: Our results aligned with clinical observations, emphasizing possible CDKI-related AEs. Conducting future clinical research is essential to confirm AE-related differences among CDKIs in older individuals.