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    FDA approves new Cubist antibiotic

    Cubist Pharmaceuticals Inc. won US regulatory approval Friday to sell a new antibiotic that fights hard-to-treat skin infections caused by Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, known as MRSA, a growing public health threat.

    The antibiotic, called Sivextro, can be taken once a day by injection or orally during a six-day course of therapy. Typically, patients will receive injections at a hospital or doctor’s office for the first day or two and then “step down” to take the drug in pill form at home.

    “As the world sees more pressure on health care costs, having an oral drug available that shows good activity against MRSA will be a big advantage for Sivextro,” said Michael W. Bonney, chief executive of Lexington-based Cubist.


    Steven C. Gilman, the Cubist executive vice president of research and development, said Sivextro will give physicians more options in treating MRSA and other Gram-positive infections.

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    “We think this is an important area of unmet medical need,” Gilman said. “We think this drug will be important for patients, for physicians, and for Cubist.”

    Sivextro is the second treatment approved by the Food and Drug Administration under the new federal Generating Antibiotic Incentives Now law, known as the GAIN Act. That law gives drug makers priority review and an additional five years of market exclusivity in order to spur the development of new antibiotics to fight the rise of drug-resistant “superbugs.”

    The first approval under the GAIN Act came last month when FDA officials gave the green light to the antibacterial drug Dalvance from Chicago-based Durata Therapeutics Inc. The agency Thursday granted priority review to another Cubist antibiotic candidate, ceftolozane/tazobactam, which treats resistant Gram-negative urinary tract and intra-abdominal infections. FDA officials are scheduled to decide by Dec. 21 whether to approve that drug.

    Bonney said Cubist will begin shipping Sivextro within days. Cubist executives will study the FDA label this weekend and will probably disclose the price of the drug next week, he said.


    Cubist will now have four antibiotics on the market. The others are its lead drug Cubicin, which also fights Gram-positive infections; Entereg, which speeds gastrointestinal recovery in patients who have had bowel surgery; and Dificid, a drug treating diarrhea caused by intestinal inflammation. Cubist acquired Dificid last year when it bought Optimer Pharmaceuticals Inc. of Jersey City, N.J.

    Sivextro itself was acquired by Cubist through the purchase of another company, San Diego-based Trius Therapeutics Inc. last summer. Products from the two acquisitions and Cubist’s own pipeline have established the Lexington company as one of the top antibiotics producers in the nation at a time when demand for such drugs is rising.

    Its latest drug approval “is the most public demonstration of what we call Cubist 2.0,” Bonney said, “which is moving from one product to a multi-product company.”

    Executives at Cubist haven’t yet estimated the size of the market for Sivextro, but they have projected that Sivextro and Dificid together could generate annual sales of $600 million to $1 billion over time. The market for ceftolozane/tazobactam, which would be one of the first new branded drugs to fight Gram-negative infections in years, could be even larger.

    Cubist employs about 1,000 workers, including 600 at its Lexington headquarters and research campus. Its sales topped $1 billion for the first time last year. Cubist stock closed at $72.24 per share Friday, up $3.69, on the Nasdaq Stock Market. News of the FDA’s approval was released after the markets closed.

    Robert Weisman can be reached at Follow him on Twitter @GlobeRobW.