Vandetanib treatment significantly prolongs progression-free survival in patients with medullary thyroid carcinoma (MTC), however, careful monitoring is essential since it can cause serious cardiovascular side effects such as hypertensive crisis and arrhythmias due to prolonged QTc, as illustrated by a case report published in Cureus.

The approval of vandetanib for the treatment of MTC was based on the results of randomized controlled clinical trials that showed that it considerably prolongs progression-free survival. 

Here, a team of researchers led by Timothy Vittorio, MD, attending cardiologist at BronxCare Cardiology Practice in New York, presented the case of an 83-year-old woman with advanced metastatic MTC. The patient was being treated with vandetanib at a dose of 300 mg per day. She developed hyponatremia, prolongation of QTc, ventricular fibrillation, and torsades de pointes. Her treatment was stopped, which led to no recurrence of torsades de pointes.


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“This is the second such case report in the literature,” first author Shoaib Ashraf, MD, and the coauthors of the study wrote. They concluded that vandetanib should be withheld until QTc is lower than 450 ms and resumed at a reduced dose once this happens.

Medullary thyroid carcinoma is a rare cancer of the thyroid gland that arises from the parafollicular or C cells. The prognosis of the disease remains poor, especially in advanced stages.

Read more about MTC prognosis

Vandetanib is a tyrosine kinase inhibitor that has selective activity against the proto-oncogene protein RET, vascular endothelial growth factor receptor 2, and epidermal growth factor receptor. It works by blocking angiogenesis and cell proliferation, and it is indicated for the treatment of symptomatic or progressive MTC that is unresectable, locally advanced, or metastatic.

Torsades de pointes is a life-threatening arrhythmia that can lead to sudden death.

Reference

Ashraf S, Shah N, Saad M, Jyala A, Vittorio TJ. Vandetanib-induced hyponatremia and torsades de pointes: a case report. Cureus. 2022;14(4):e24556. doi:10.7759/cureus.24556