Tetraphase shares tank as FDA demands new antibiotic PhIII trial

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Tetraphase ($TTPH) saw its share nosedive by 24% afterhours last night as the FDA said its lead drug candidate had to undergo a new late-stage study--delaying any approval by several years and adding new costs to its development.

The Watertown, MA-based biotech said that its experimental IV antibiotic eravacycline--which is seeking to treat drug-resistant bacteria--had been the focus of an FDA letter asking for extra data from an additional, positive Phase III trial. This must be done, the regulator said, before it will support an NDA submission.

This compounds more woe on the biotech as in September of last year a pivotal trial for countering urinary tract infections flopped, and investors responded by slashing the value of its shares by a whopping 80%. In 2014 however it did post a positive outcome for a Phase III study targeting complicated intra-abdominal infections.

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Based on the FDA’s response, Tetraphase said in a statement that it will in fact do two new studies: the first, for twice-daily IV eravacycline in patients with complicated intra-abdominal infections (cIAI). 

The study is set to take place early in the fourth quarter of 2016 with top-line results available a year after this--which the company hopes will be enough to support an NDA.

And for the second, Tetraphase said it plans to conduct another Phase III clinical trial for once-daily IV eravacycline in patients with complicated urinary tract infections (cUTI). This too, if positive, will go toward a supplementary NDA for an additional indication of cUTI.

“With a written response from FDA now in hand, we have a confirmed path forward which requires one additional successful Phase III trial to support an NDA filing for eravacycline,” said Guy Macdonald, Tetraphase’s president and CEO.   

“We have determined that a trial evaluating IV eravacycline in cIAI provides for the most rapid path to approval, and most importantly, the most rapid path to making eravacycline available to patients.  We expect that our existing cash resources are sufficient to fund operations through the data readout for this planned cIAI clinical trial. In parallel, we plan to conduct another Phase III trial evaluating IV eravacycline in cUTI, and assuming a successful outcome, will use those results to support an sNDA.”

The company also has two other antibiotics in its pipeline, but these are both preclinical. It’s also facing pressure from Big Pharma Roche ($RHHBY) and Merck ($MRK) which are also both seeking to get in on this market.

But the CDC and governments around the world have long been crying out for the industry to develop more antibiotics that deal with drug resistant bacteria--with some warning that people could soon face the prospect of once again dying from basic infections due to a lack of effective drugs due to antimicrobial resistance.

The biotech’s shares were down 24% in afterhours trading but even before the bad news, it was already down almost 55% year-to-date.