CDK4/6 inhibitor-induced digoxin intoxication: 2 case reports

SUMMARY

Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors are frequently used in combination with endocrine therapy for the treatment of hormone receptor positive breast cancers. This paper reports two cases of patients with digoxin intoxications due to CDK4/6 inhibitors, one involving ribociclib and the other abemaciclib. Digoxin intoxication can lead to fatal arrhythmias, highlighting the need for further research to analyse and clarify the underlying pathophysiology. It is advisable to monitor drugs with a narrow therapeutic index when prescribing CDK4/6 inhibitors. Importantly, common medication interaction checkers such as Uptodate, Medscape and WebMD do not report interactions between CDK4/6 inhibitors and digoxin.

(BELG J MED ONCOL 2025;19(2): 73–77)