Myocarditis in a 47-Year-Old Man with Myasthenia Gravis and Malignant Thymoma Following the Administration of a Tyrosine Kinase/CDK Inhibitor

Summary A 47-year-old man was admitted to an intensive care unit for increasing respiratory distress, persistent diarrhoea and general decline on a background of longstanding myasthenia gravis and metastatic thymic carcinoma. He had recently been involved in a phase 1 clinical trial with the drug FN-1501- an inhibitor of cyclin dependent kinases CDK2/CDK4/CDK6 and tyrosine kinase (TK) FLT3. The patient was found to have severe systolic dysfunction on echocardiography, consistent with myocarditis, for which he required inotropic support. It was only partially responsive to steroid treatment. In combination with the patient’s myasthenia gravis and deconditioning, the myocarditis contributed to the patient’s continued decline and ultimate death. This case explores the possibility that the patient’s myocardial injury and subsequent death was related to the trial drug FN-1501. An association between TK inhibitors and cardiotoxicity has been outlined in the past but the cardiac effects of CDK inhibitors is still in question. There is no data presently implicating FN-1501.