AstraZeneca has been boosted by the news that regulators in the USA have given the green light to vandetanib for a rare form of thyroid cancer.

The US Food and Drug Administration has approved vandetanib, which is a kinase inhibitor and has no brand name yet, to treat adult patients with late-stage medullary thyroid cancer who are ineligible for surgery and who have disease that is growing or causing symptoms. The once-daily oral treatment is the first agency-approved drug for MTC, which is estimated to represent 3%-5% of all thyroid cancer and its estimated incidence in the USA for 2010 is about 1,300-2,200 patients.

In December, an FDA advisory board recommended approval of vandetanib based on data from the Phase III ZETA study, which involved 331 patients with advanced MTC. Median progression-free survival was 16.4 months in the placebo arm and at least 22.6 months in the vandetanib arm.

The FDA was expected to make a decision in January but put back the date to April in order to examine further a risk evaluation and mitigation strategy (REMS) for vandetanib provided by AstraZeneca. Only prescribers who are certified through the REMS programme can dispense the drug as it was shown to affect the electrical activity of the heart, which in some cases can cause irregular beats that could lead to death.

First AZ-developed orphan drug OK

Richard Pazdur, director of the Office of Oncology Drug Products in the agency's Center for Drug Evaluation and Research, said that the approval "underscores FDA’s commitment to approving treatments for patients with rare and difficult-to-treat diseases". Howard Hutchinson, chief medical officer at AstraZeneca, noted that vandetanib is the first treatment company has developed and brought to market under orphan drug designation in the USA.

Vandetanib, which is also under regulatory review in the European Union and Canada, was originally touted as a blockbuster for advanced non-small cell lung cancer. However, AstraZeneca withdrew marketing applications in the USA and Europe in October 2009 for the drug in NSCLC, then known as Zactima, as it demonstrated no overall survival advantage.

Now analysts believe vandetanib sales are more likely to be in the region of $80-$100 million.