Dr. Sherman on Vandetanib's Dosage and Precautions

Eric J. Sherman, MD, Head and Neck Oncology, Memorial Sloan-Kettering Cancer Center, discusses two of the leading concerns for the oral kinase inhibitor vandetanib (Caprelsa), an FDA approved treatment for medullary thyroid cancer.

Following the positive results that eventually led to the approval of vandetanib the FDA expressed two main concerns over the possible side effects and dosing strategy for the agent.

The first concern was over QTc interval prolongation, which may lead to cardiac events. Despite this concern, few patients on the vandetanib trial actually experienced this type of adverse reaction. The possibility of cardiac events led the FDA to require certification before the agent could be prescribed. Sherman notes, the registration process involves a short online course describing recommendations, monitoring, and when to discontinue or adjust therapy.

Secondly, the FDA expressed concerns over the starting dose of 300 mg per day, which was used in the trial and was shown to increase progression-free survival to 22.6 months compared with 16.4 months for placebo. This concern was further substantiated by another phase II trial investigating vandetanib that used a 200 mg daily dose; this trial demonstrated similar positive results.

A 300 mg a day initial dose of vandetanib is currently approved by the FDA with the recommendation to reduce the dose to 200 mg for patients with moderate to severe renal impairment or dose modifications for severe toxicities.