Coronary Plaque Erosion after Abemaciclib Treatment Onset: An Unknown Side Effect?

CDK4/6 inhibitors in the treatment of metastatic breast cancer: Focus on toxicity and safety

The development of oral cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors, including palbociclib, ribociclib, and abemaciclib, has revolutionized the treatment landscape for patients with hormone-receptor-positive (HR+) and human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (BC). When combined with an aromatase inhibitor or fulvestrant, these agents have been approved as first-line therapy in the metastatic setting. Abemaciclib has also gained FDA approval for patients with HR-positive, HER2-negative, node-positive, early BC at high risk of recurrence. Moreover, ribociclib has recently improved disease-free survival in patients with stage II or III HR+/HER2-negative early BC. CDK4/6 inhibitors have favorable safety profiles. However, the available agents have different toxicity profiles that must be clearly discussed with the patients for optimal clinical decisions. This manuscript aims to review CDK4/6 inhibitor-related treatment-associated adverse events, identify risk factors for intolerable adverse events, and assess their safety in special patient populations such as the elderly and those with renal insufficiency. Enhanced knowledge and understanding of CDK4/6 inhibitor-related toxicities can improve treatment strategies and ultimately enhance patient care.

Thromboembolic Events with Cyclin-Dependent Kinase 4/6 Inhibitors in the FDA Adverse Event Reporting System

Simple Summary

This post-marketing research addressed the role of cyclin-dependent kinase 4/6 inhibitors, relatively new anticancer drugs approved for advanced breast cancer in cancer-associated thrombosis. We used the Food and Drug Administration pharmacovigilance database to retrospectively assess thromboembolic events in the real world. A potential class effect was found for venous thrombosis, whereas distinctive arterial events emerged for ribociclib. These signals call for both prospective research and early proactive monitoring by oncologists, also in patients without apparent risk factors. These findings strengthen the role of timely pharmacovigilance to detect and characterize post-marketing adverse events of special interest, thus supporting patient care.

Abstract

We analyzed thromboembolic events, recognized (AESIs), with cyclin-dependent kinase (CDK)4/6 inhibitors, using the Food and Drug Administration adverse event reporting system. Methods: Thromboembolic events were characterized in terms of spectrum [venous and arterial thromboembolism (VTE; ATE)] and clinical features by combining the disproportionality approach [reporting odds ratio (ROR) with 95% confidence interval (CI)] with individual case assessment. Results: A total of 1722 thromboembolic events were retained. Increased VTE reporting emerged for CDK4/6 inhibitors in the exploratory analyses (n = 659; ROR = 1.51; 95% CI = 1.39–1.63), with consistent disproportionality in the consolidated analyses (e.g., deep vein thrombosis with abemaciclib: 17; 1.98; 1.22–3.19). Higher-than-expected ATE reporting was found for ribociclib, including myocardial infarction (41; 1.82; 1.33–2.48), with rapid onset (median latency 1 vs. 6 months for other CDK4/6 inhibitors). Causality was highly probable or probable in 83.2% of cases, with a negligible proportion of pre-existing drug- and patient-related risk factors except for cardiovascular comorbidities (26%). Conclusions: Although causal association cannot be firmly inferred, oncologists should proactively monitor the occurrence of VTE with CDK4/6 inhibitors. The unexpected distinctive increased ATE reporting with ribociclib deserves urgent clarification though large comparative population-based studies. We support pharmacovigilance for the post-marketing characterization of AESIs, thus promoting real-time safe prescribing in oncology.