Optimer Pharmaceuticals has some bad news out today. The San Diego-based developer of antibiotics said it has halted a study of an experimental antibiotic for traveler’s diarrhea after a higher than expected rate of skin rashes. Shares of Optimer (NASDAQ: [[ticker:OPTR]]) fell more than 15 percent after the news broke.
The company made the disclosure today in an 8-K filing with the Securities and Exchange Commission. Optimer said it informed the FDA yesterday that it was halting a study that looked at interactions between prulifloxacin (Pruvel) and antacids. The rashes were “mild in severity, and required little or no treatment and all resolved completely,” the company said in the filing. Optimer is now going to investigate the cause of the rashes, and said it can’t estimate how long it might delay its new drug application for the product, which has already passed a pair of pivotal Phase III trials which didn’t show any increased rates of rashes.
This is certainly an unhappy surprise for Optimer, but it would be a stretch to call it devastating because this isn’t the company’s primary asset in development. Most of Optimer’s value is based on its lead antibiotic, fidaxomicin, for deadly “C.diff” infections that people get in the hospital. Optimer’s strategy with its second drug, which then-CEO Michael Chang explained to me in January 2009 feature story, was to create a more potent alternative to Bayer’s ciprofloxacin (Cipro). The total market up for grabs isn’t huge—an estimated $200 million. Optimer hoped to capture some of that to provide a secondary revenue stream, the company said at the time.
Both the Bayer drug and Optimer’s candidate are members of the antibiotic class known as fluoroquinolones, which are known to sometimes cause rashes, Optimer said in its statement today. You can read more about this compound’s past clinical trial results by checking a summary on the Optimer website.
