Cubist turns positive on good news from gram-negative antibiotic

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Positive data for Cubist Pharmaceuticals’ antibiotic CXA-201 is a good sign for what could very well be a bigger seller than its marketed product Cubicin. The new project has now shown that it is the equal to existing products in combating hospital-acquired infections, offering physicians a new weapon against those gram-negative bacteria in which resistance has become a problem.

Analysts have pencilled in blockbuster peak sales for the intravenous treatment. For now, the agent looks like it has a good shot at approval and becoming the Massachusetts group’s biggest growth driver.

Two for two

Cubist reported on Monday that CXA-201, known generically as ceftolozane/tazobactam, in combination with metronidazole was non-inferior to AstraZeneca’s Merrem in curing complicated intra-abdominal infections. These are most commonly caused by the microbes Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa.

This news followed the announcement last month that the antibiotic was also non-inferior to levofloxacin in treating complicated urinary tract infections, which in hospitals are associated with the same set of bacteria and are frequently related to the use of catheters.

Of the two, the abdominal infection study was thought to be slightly higher risk, as phase II data showed the project to be numerically inferior to Merrem – although that 122-patient trial was clearly not powered to show non-inferiority. Enrolling 1,000 patients in the abdominal infection phase III programme was sufficient to show that CXA-201 was equal.

Reporting positive pivotal data clears the way for a filing in mid-2014, putting approval in 2015. Shares rose 6% to $66.51 on the news yesterday.

Cubist is planning a study in a third indication, ventilator associated pneumonia, beginning next year, with data not due until 2016 and filing not likely until 2017.

Looking for growth

With phase III success and regulators anxious to approve new antibiotics as older ones lose effectiveness, forecasts for CXA-201, already Cubist’s biggest growth driver, seem likely to rise in the coming months. As it is, the antibiotic is estimated to bring in $473m in 2018, making it the third-biggest branded antibacterial on the market after GlaxoSmithKline’s Augmentin IR and Cubist’s own gram-positive treatment Cubicin, according to EvaluatePharma forecasts.

Indeed, Cubist seems to be the only company working almost exclusively in the antibacterial space, with near 90% of its forecast $2bn sales coming from Cubicin, ‘201, the Clostridium difficile drug Dificid and skin infection treatment tedizolid. The last two came from acquisitions of Optimer Pharmaceuticals and Trius Therapeutics just this year in a bid to beef up Cubist's armoury of novel antibiotics (Cubist right to inject caution into much-needed acquisition spree, July 31, 2013).

Both these acquired products are a help, but with Cubicin’s market exclusivity growing short – generic launch is expected in mid-2018 after the Staphylococcus aureus drug manages to achieve blockbuster sales – Cubist is in need of a new growth driver. With potential blockbuster sales mooted by analysts like Morgan Stanley and Goldman Sachs, CXA-201 could be just what the doctor ordered.

To contact the writer of this story email Jonathan Gardner in London at jonathang@epvantage.com or follow @JonEPVantage on Twitter

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