FDA staffers back Pfizer's Prevnar vax for adults

Will Pfizer ($PFE) succeed at broadening use of its star vaccine? A report from FDA reviewers suggest it might. In a pre-advisory committee review, agency staffers said the Prevnar 13 vaccine was effective at staving off pneumococcal infections in adults over 50. The vaccine also appears to be as safe as an older version from Merck ($MRK), the FDA reviewers concluded.

Pfizer wants to expand Prevnar's reach beyond childhood; the vaccine is currently FDA-approved for children from 6 weeks to 5 years old. It's been for sale in the U.S. since last year, and globally, Prevnar 13 and its predecessor Prevnar brought in $3.7 billion in 2010. With the loss of exclusivity on Lipitor coming Nov. 30, the Prevnar vaccines are poised to become Pfizer's biggest-selling franchise. The more patients it can reach, the more it can help fill the vast Lipitor void.

Besides the fact that FDA's reviewers figure that Pfizer's app for expanded approval "met the requirements for licensures as agreed," as Dow Jones reports, the staff's assessment of its efficacy in comparison with Merck's Pneumovax 23 is significant. Agency staff said that Prevnar 13 offered an improved immune response compared with Pneumovax.

Using Prevnar 13 as a booster for previous Pneumovax 23 immunizations also proved to be an improvement compared with a Pneumovax booster, the reviewers said. And Merck's vaccine was effective against invasive pneumonia, but didn't show an effect on pneumococcal pneumonia, Reuters reports, which is more common in adults.

An FDA advisory panel will meet to discuss the Prevnar 13 data on Wednesday, and the agency is expected to decide on the new indication by January.

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