Antigenics Shares Plummet as Cancer Vaccine Application Rejected in Europe

Xconomy Boston — 

Antigenics, the Lexington, MA-based developer of a personalized treatment to stimulate the immune system to fight cancer, saw its shares plummet today after a European regulatory commission told the company that its lead drug candidate isn’t ready for the marketplace.

Shares of Antigenics (NASDAQ: AGEN) dropped 40 percent to $1.25 at noon Eastern time after the company said European Union regulators told it they have a negative opinion of the firm’s drug. Antigenics says it will “evaluate its options,” and that it might appeal the decision by the Committee for Medicinal Products for Human Use, a unit of the European Medicines Agency. The company was seeking approval to start marketing vitespen (Oncophage) for patients with kidney cancer.

“With the considerable support of the urology and oncology communities, we will continue to evaluate our options,” said Garo Armen, chairman and CEO of Antigenics, in a statement.

Antigenics’ application was a controversial one from the start. The main clinical trial supporting the product failed to reach its primary goal, so Antigenics has made its argument on looking at a subpopulation of trial patients who appeared to benefit. That’s because while the trial of 604 patients failed to show the Antigenics drug could lower the risk of relapse after kidney tumors were surgically removed, vitespen did help 60 percent of people stay in remission longer if they had an intermediate risk of recurrence, the company said.

That sort of “subset analysis” of patients is generally considered a “fishing expedition” by the FDA, and isn’t good enough to win approval here in the U.S. Antigenics had been hoping to find a friendlier audience in Europe by following a procedure known as “conditional approval,” a European Union regulatory provision introduced in April 2006 that provides patients access to new drugs when no satisfactory treatment option is readily available. More than 60,000 people were diagnosed with kidney cancer in EU member countries in 2004, and about half that many died, according to the company. Antigenics said it had three meetings to consult with European regulators to sort through the options before it went ahead and asked for approval a year ago.

The Antigenics application is being watched closely, not just because of the regulatory pathway the company hopes to follow, but because of the drug’s unusual mode of action as a “cancer vaccine.” The Antigenics treatment is designed to be personalized, made by slicing out a portion of a patient’s tumor. The tumor tissue is frozen and shipped to the Antigenics plant in Lexington, where it is chopped up and key proteins filtered out. The treatment is shipped back to the doctor and injected into the patient to “teach” the immune system to spot the hallmarks of cancer cells and mount a defense against them.