They still asked that agency advisers, set to meet Feb. 22 on the drug, consider whether more risk data should be gathered by the company before approval. Qnexa is one of three obesity medications vying to be the first in 13 years on the market.
The drug, which analysts have said may generate $448 million in sales in 2015, combines the appetite suppressant phentermine with topiramate, an antiseizure and migraine medicine. Vivus, based in Mountain View, California, has proposed a post-approval trial to assess Qnexa against placebo in reducing major heart events in an obese, at-risk population.
“The positive here is the FDA is saying exactly what the data says,” said Jason Butler, an analyst with JMP Securities in New York said in a telephone interview. “This drug has risk, it has side effects. The benefit here is compelling.”
Vivus rose 7.3 percent to $11.99 at 4 p.m. New York time, after jumping 43 percent in the 12 months before today.
The FDA also plans to have advisers discuss in March the possibility of requiring heart risk studies for obesity drugs.
Agency staff wrote that they have the authority to restrict certain patients from using Qnexa “to ensure the benefits of a drug outweigh the risks” while minimizing “the burden on the health-care system and the barriers to patient access.” Severely restricting topiramate is not practicable because it is also treats other serious conditions, the staff wrote.
Analysts varied on their take on the FDA staff report.
While Butler said the documents give Vivus a good opportunity to convince the panel Qnexa deserves approval, Steve Yoo, an analyst with Leerink Swann & Co. in New York, said in a note to clients today they suggest the drug will not be approved by April 17, when the FDA is due to make a decision. The briefing documents indicate the FDA is taking “a cautious stance,” Yoo said.
The membership on the panel that will meet Feb. 22 is “somewhat negatively biased,” Michael King, an analyst at Rodman & Renshaw in New York, wrote in a note to clients today. Five members have previously voted against one of the three experimental obesity drugs and four in favor, he said.
The panel meeting “should be like a New York football Giants game, decided in the last minute by a field goal,” King said.
Orexigen Therapeutics Inc. (OREX), based in La Jolla, California, and San Diego-based Arena Pharmaceuticals Inc. (ARNA) also are seeking approval for their obesity medicines, which the FDA refused to approve without more data on safety risks.
More than one-third of U.S. adults are obese, and another third are overweight, according to the Centers for Disease Control and Prevention. The obesity rate among adults has more than doubled since 1980 to 72 million people.
Obesity raises the risks of diabetes, heart attacks and stroke, and costs the U.S. economy an estimated $147 billion a year in medical expenses and lost productivity, according to the Atlanta-based CDC.
Topiramate is the active ingredient in Johnson & Johnson’s Topamax. The anticonvulsant is also associated with confusion, difficulty with concentration and memory loss.
Vivus examined medical claims data and found five oral clefts in a group of 1,740 children whose mothers had taken topiramate alone in the first trimester of pregnancy, for a prevalence rate of 0.29 percent, the company said Dec. 21 in a statement. That compared with a rate of 0.16 percent in the group whose mothers had taken antiseizure drugs, including topiramate, before pregnancy.
Vivus plans to finish the results in the third quarter of this year, after the April 17 deadline for the FDA to decide whether to approve the drug. The risk of oral clefts has not been fully answered by the interim data, FDA staff said.
The FDA asked Vivus in January to remove wording from Qnexa’s prescribing label advising women with the potential to become pregnant against taking it.
There’s a significant need for new obesity therapies, said Joseph Nadglowski, president of the Obesity Action Coalition, a patient advocacy group in Tampa, Florida.
“We really go from Weight Watchers to bariatric surgery when it comes to treatment options,” Nadglowski said in an interview. “For many, that’s a pretty big gap.”
The FDA hasn’t approved a prescription drug for long-term weight loss since Swiss drugmaker Roche Holding AG (ROG)’s Xenical in 1999. London-based GlaxoSmithKline Plc (GSK)’s Alli, a half-dose version of Xenical’s active ingredient, won FDA clearance in 2007 as the first diet drug available without a prescription.
The drugs’ active ingredient, orlistat, blocks the body’s absorption of fat. Xenical brought in $269 million in revenue in fiscal 2011, according to data compiled by Bloomberg.
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