[A Case of Significant Ejection Fraction Reduction and Heart Failure Induced by Osimertinib]

In recent years, osimertinib has been increasingly used as a therapeutic drug for epidermal growth factor receptor(EGFR)mutation-positive lung cancer, with heart failure rarely reported as an adverse event. We report here a case of a significantly decreased ejection fraction and heart failure that were induced by osimertinib. We consider the case important and include a discussion of relevant previous reports.

The patient was a 73-year-old woman who had been on oral gefitinib as first-line treatment for EGFR mutation-positive(exon19 deletion)non-small cell lung cancer for approximately 1 year and 2 months. Thereafter, she tested positive for an EGFR resistance mutation(T790M); and accordingly, oral osimerti- nib was started at 80mg/day as second-line treatment. After continuing this treatment for 6 months with no particular adverse events, she visited our hospital and was found to have dyspnea on exertion and increased pleural effusion. Based on these findings, cancer relapse was suspected, and the patient was hospitalized for detailed examinations. She was diagnosed with heart failure based on the elevated BNP level that was found in a blood test and CT and echocardiography findings, and her ejection fraction deteriorated to 19% from a pretreatment level of 59%. The conditions improved after diuretic and b- blocker treatment. Given the absence of any possible cause of heart failure or reduced ejection fraction in her past history of illness and medication, we concluded that these conditions were induced by osimertinib.

While heart failure induced by EGFR-TKIs has been rarely reported, osimertinib may cause cardiomyopathy due to human epidermal growth factor receptor type 2(HER2)inhibitory activity.