Evaluation of the QTc interval during lenvatinib treatment in radioiodine-refractory differentiated thyroid cancer: reports from the real-life clinical practice

As for other tyrosine kinase inhibitors, a prolongation of ECG-recorded QTc intervals may be observed during lenvatinib treatment; a warning on this phenomenon has been stated. However, methods and frequency of ECG recordings have seldom been reported in this context. We present two cases of patients treated with lenvatinib for radioiodine-refractory differentiated thyroid cancer in whom the QTc interval was long monitored through a weekly 12-lead ECG registration. Overall, the maximum QTc increase above baseline was 3 and 31 ms in the first and second patient, respectively. QTc interval did not reach the toxicity value for drug withdrawal in either of the patients. These data may provide further information on cardiac safety profile of lenvatinib in a real-life practice.