FDA staff note risks of AstraZeneca cancer drug

An experimental AstraZeneca pill to treat inoperable thyroid cancer carries “substantial toxicity” for patients, U.S. drug reviewers said in documents released on Tuesday.

The U.S. Food and Drug Administration staff said they would ask an advisory panel to consider skin, lung and other risks with the drug, vandetanib, at a public meeting on Thursday.

The drug was once seen as a potential blockbuster but it suffered a major setback after failing to extend survival in patients with lung cancer.

Treating thyroid cancer is a much smaller market. Analysts forecast vandetanib sales of $62 million in 2014, according to Thomson Reuters consensus estimates.

The FDA will ask the advisory panel if the drug’s benefits outweigh risks and if use should be limited, given possible side effects.

AstraZeneca said its research showed vandetanib delayed cancer growth by 11 months more than a placebo.

FDA reviewers said the effectiveness needed to be weighed against serious health problems that were reported in 31 percent of vandetanib patients, compared with 13 percent who got a placebo. The potential side effects included interstitial lung disease, a serious lung disorder, a potentially dangerous skin rash called Stevens-Johnson Syndrome, and strokes, FDA reviewers said.

“Given the substantial toxicity seen with vandetanib, should its indication be limited to patients with progressive, symptomatic medullary thyroid cancer?” FDA reviewers wrote in a summary prepared for the panel.

Medullary thyroid cancer (MTC) is rare. Early-stage cases can be treated by removing the thyroid, but there are no approved options for advanced cases that cannot be surgically treated. About 40 percent of patients live for five years after the disease has spread to distant sites in the body, FDA staff said.

There are about 2,000 new MTC patients each a year in the United States and a similar number in Europe, and about half could benefit from vandetanib, AstraZeneca has said.

The company, in a separate summary released by the FDA, said vandetanib showed a “compelling benefit” for patients with no effective treatment options. It said side effects could be managed by reducing the original dose, if needed.

The FDA usually follows panel recommendations when deciding whether to approve new drugs. A final FDA decision is due by January 7.

AstraZeneca is relying on new products to offset expiring patents on some of its best-selling medicines, such as heartburn treatment Nexium and Seroquel for schizophrenia. The company has placed big bets on cancer pills like vandetanib, with mixed results.

Lung cancer pill Iressa has seen a revival thanks to tests that show which patients will gain from using it. But another cancer pill, Recentin, was dropped as a candidate for first-line colon cancer treatment.

The proposed brand name for vandetanib is Zictifa.

Shares of the Anglo-Swedish drugmaker were down 0.4 percent in London on Tuesday.

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By Lisa Richwine

WASHINGTON