Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Cubist Pharmaceuticals (NASDAQ:CBST), a biopharmaceutical company focused on developing acute-care therapies, advanced by as much as 11% after announcing positive late-stage data for its complicated urinary-tract-infection antibiotic, ceftolozane/tazobactam, also known as CXA-201.

So what: According to Cubist's press release, the antibiotic CXA-201 met the trials' primary endpoint of noninferiority to levofloxacin, which entailed a "microbiological eradication and clinical cure rate five to nine days after the end of therapy." Cubist also notes that while the trial wasn't designed to test the superiority of its antibiotic, a secondary analysis would suggest the potential for superiority over levofloxacin.

Now what: Now shareholders wait patiently for the phase 3 data on how this antibiotic performs in complicated intra-abdominal infections, which could be a much bigger market. It could also have applications in an even broader sense with treating hospital-acquired/ventilator-associated bacterial pneumonia, which it's also aiming to treat with experimental compound tedizolid phosphate. It's certainly an exciting time to be a Cubist shareholder and it's quite possible that a number of new compounds from its pipeline could be approved if things keep going its way. I would certainly suggest keeping Cubist on your watchlist moving forward.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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