Cubist's superbug drug clears FDA panel, lines up for Pfizer showdown

Cubist's ($CBST) latest antibiotic won praise from a panel of FDA advisers, setting the stage for a likely approval and head-to-head competition with Pfizer's ($PFE) blockbuster Zyvox.

The FDA's Anti-Infective Drugs Advisory Committee voted 14-0 to recommend approval for Cubist's tedizolid phosphate to treat acute bacterial skin infections, which are caused by drug-resistant pathogens including MRSA. The drug can be administered either orally or intravenously, and Cubist plans to market it under the brand name Sivextro.

The FDA is not bound to follow the recommendations of its advisers, though it often does, and the agency is due to make a final decision on Sivextro by June 20.

If Cubist's drug wins an expected approval, its commercial future will be closely tied to how it performs against Pfizer's well-established antibiotic, which pulled in $1.4 billion last year. In Phase III trials, Cubist's candidate proved itself non-inferior to Zyvox, and the drug boasts fewer side effects along with less frequent dosing and shorter treatment times.

That said, Zyvox is set to lose patent protection in 2015, meaning Sivextro could face a generic-flooded market early in its commercial life. Still, depending on pricing, Cubist's drug will likely have a fighting chance against even generic Zyvox, as late-stage studies found Sivextro could be taken once a day for 6 days versus twice daily for up to two weeks for Pfizer's drug.

Meanwhile, Cubist is all in on antibiotic R&D, planning to spend about $400 million this year alone in hopes of delivering four new treatments by 2020. Behind Sivextro is ceftolozane/tazobactam, a drug designed to treat complicated urinary tract and intra-abdominal infections, and Cubist plans to submit regulatory applications for that therapy in the first half of 2014. The companies pipeline includes therapies for hospital-acquired bacterial pneumonia, Clostridium difficile and opioid-induced constipation.

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