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Eisai’s Perampanel Didn’t Significantly Reduce Epileptic Seizures in Study

Eisai Co.’s experimental epilepsy drug didn’t cut seizure rates significantly more than a placebo in patients who didn’t improve on previous treatments, a researcher said at the American Academy of Neurology meeting.

While the study failed to find a definitive benefit for its two main goals, a third analysis favored by U.S. regulators showed patients had 26 percent to 35 percent fewer seizures over 28 days on perampanel, compared with 21 percent in those on a placebo, said Jacqueline French, director of the clinical trials consortium at New York University’s epilepsy center.

The Eisai-funded study, from the last of three stages usually needed for U.S. approval, included patients who failed to respond to as many as a dozen drugs and had few treatment alternatives, French said in a news conference on April 12 at the neurology meeting in Honolulu. Patients received the drug or placebo on top of existing therapy. The results should be enough to win approval from the Food and Drug Administration, she said.

“There was already a positive trial at lower doses,” said French, the study’s lead researcher. The FDA and the European Medicines Agency will “look at the entirety of the data,” she said. “They won’t have a problem approving the drug with data that’s available.”

Regional Difference

The benefits were most significant for patients from the U.S. and Canada, while those from Latin America weren’t helped, she said. Additional research is needed to determine why there was such a regional difference, she said.

Eisai fell 1.5 percent to 2,966 yen at the 3 p.m. close of trading on the Tokyo Stock Exchange. The shares have risen 0.9 percent this year, compared with a 5.8 percent drop in the benchmark Topix index.

When researchers considered the results of everyone assigned to take the drug, a so-called intent-to-treat analysis, the patients taking perampanel had fewer seizures and were more likely to have halved their seizure rates than those given a placebo. The differences between the groups were too small to be considered significant, and they may have stemmed from chance, the study found.

The data paint a “mixed picture,” said Stephen Barker, an equities analyst at MF Global FXA Securities Ltd. in Tokyo, who rates Eisai a “sell.”

Under U.S. standards, the 12 milligram dosage was effective in both the double-blind and in the maintenance phase of the trials, while the 8 milligram dosage wasn’t proven to be better than placebo in the maintenance phase, Barker said in an e-mail. Under the European guidelines neither dose was proven, at a high level of confidence, to be better than placebo.

‘Disappointment’

“In the Latin American arm of the study, perampanel was not shown to be better than placebo,” Barker said. “I would consider this to be something of a disappointment, and raises the risks in my mind that this drug may not get approval.”

About 50 million people worldwide have epilepsy, a chronic disorder of the brain where abnormal activity of the neurons causes seizures. Pinpointing the specific reason an individual develops the disease is often difficult.

Eisai has said it plans to file for approval of perampanel in the U.S. and Europe by mid-year. The Tokyo-based drugmaker, which fired 20 percent of its U.S. workforce in the past two months, is looking for novel medicines to replace dwindling sales of Aricept, its best-selling medicine for Alzheimer’s disease that lost patent protection in November.

Among the side effects were dizziness, tiredness, irritability, headaches and falls, according to the study.

Perampanel blocks receptors present in neurons that transmit signals stimulated by glutamate within the brain. The overactive receptors are believed to be involved in diseases marked by excess signaling within the brain, including epilepsy, movement disorders, pain and some psychiatric conditions.

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net

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