CDK 4/6 inhibitor successful rechallenge after limiting hepatic toxicity.

A 59-year-old woman presented with a bone-only metastatic luminal breast cancer. She received first-line treatment with aromatase inhibitors associated with a cyclin-dependent kinase (CDK) 4/6 inhibitor, ribociclib. She developed Grade 3 elevated transaminases leading us to interrupt ribociclib permanently. Specific toxicity of the CDK 4/6 inhibitor ribociclib was retained. Once transaminase levels normalized, the patient initiated another CDK4/6 inhibitor, palbociclib, using an escalating dose without reappearance of hepatic injury. This case suggests the possibility of rechallenge after hepatic toxicity with a different CDK 4/6 inhibitor using dose escalation and careful monitoring.