[A Case of Drug-Induced Lung Injury That Developed the Day after Abemaciclib Treatment for Advanced Breast Cancer].

A 74-year-old woman was diagnosed with invasive breast ductal carcinoma, cT2N0M1 (PUL), stage Ⅳ, and treated with abemaciclib and letrozole. The day after drug administration, the patient developed a fever of 38℃ and dyspnea upon exertion, and was diagnosed with drug-induced pneumonia. Steroid pulse therapy was administered during hospitalization, and the patient was discharged after the dose of prednisolone was gradually reduced. This case shows that, when abemaciclib is administered, drug-induced lung injury can occur within 1 week.