Rechallenge of an alternative CDK 4/6 inhibitor after hepatotoxicity in the treatment of hormone-positive metastatic breast cancer.

IntroductionCyclin Dependent Kinase (CDK) 4/6 inhibitors are changing the landscape of breast cancer treatment. These medications are generally well-tolerated, but incidences of hepatotoxicity have been reported in the literature.Case ReportIn this case, we present a 36-year-old Caucasian female who was diagnosed with hormone-receptor (HR) positive, human epidermal growth factor receptor 2 (HER2) negative metastatic breast cancer who initiated first line treatment with an aromatase inhibitor and a cyclin-dependent kinase (CDK) 4/6 inhibitor, ribociclib. Following treatment initiation, she experienced grade 4 hepatoxicity.Management and OutcomeRibociclib was discontinued due to probable cause of hepatotoxicity based on a Naranjo score of 7. Once her liver enzymes resolved to grade 1 toxicity, she was transitioned to another CDK 4/6 inhibitor, palbociclib. The patient has remained on palbociclib for 1 year of treatment with normalization of her liver function enzymes and stable disease.DiscussionThis case presents a successful rechallenge of an alternative CDK 4/6 inhibitor after grade 4 ribociclib-induced hepatotoxicity and reviews similar cases of ribociclib-induced hepatoxicity and management strategies.