Hematological Events Potentially Associated with CDK4/6 Inhibitors: An Analysis from the European Spontaneous Adverse Event Reporting System

Cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors are a recent targeted therapy approved for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2 negative (HER2−) advanced breast cancer. Abemaciclib, palbociclib ribociclib demonstrated great efficacy safety during clinical studies. However, differences in their adverse-event profiles have been observed. This work aims to describe the suspected adverse drug reactions (ADRs), such as leukopenia thrombocytopenia, reported each CDK4/6 inhibitor EudraVigilance (EV) database. Data on individual case reports (ICSRs) were obtained by accessing European spontaneous reporting system via EV website. Information concomitant therapy, including fulvestrant, letrozole, anastrozole exemestane, was also analyzed. A total of 1611 ICSRs collected from Most classified serious cases both thrombocytopenia ADRs. most had recovered/resolved. On contrary, abemaciclib mostly characterized non-serious cases. Abemaciclib often combined while generally associated letrozole. Pharmacovigilance studies crucial early identification potential ADRs better differentiate toxicity profile different inhibitors, particularly real-world setting.