Paratek shares surge after antibiotic phase 3 hits endpoints

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Paratek plans to file an NDA for omadacycline with the FDA early in 2018.

Shares in Paratek Pharmaceuticals jumped 35% in premarket trading on the back of data from a phase 3 trial of its antibiotic candidate omadacycline. The clinical trial met its primary endpoint of noninferiority to moxifloxacin, teeing Paratek up to file for FDA approval in the first quarter of next year.

Boston, Massachusetts-based Paratek enrolled 774 patients with community-acquired bacterial pneumonia and randomized them to receive either omadacycline or moxifloxacin, a synthetic fluoroquinolone agent developed by Bayer. Paratek then looked at how many patients in each cohort survived and improved on two of four symptoms in the 72 to 120 hours after treatment started and assessed the number of subjects whose symptoms cleared up in the five to 10 days after treatment ended.

Omadacycline delivered on both counts. In the intention-to-treat population, 81.1% of patients in the omadacycline cohort responded to the experimental drug in the first three to five days of treatment. The number in the moxifloxacin arm was 82.7%, resulting in the trial hitting its primary endpoint of noninferiority. And omadacycline matched moxifloxacin against the second endpoint. The symptoms of more than 90% of subjects in both arms resolved in the post-treatment window.

Paratek thinks the data are strong enough to win it approval on both sides of the Atlantic, but it will take the company up to 12 months to get the first of its applications together.

“This phase 3 study in pneumonia along with our previously announced successful phase 3 study in skin infections satisfy the regulatory filing requirements of our special protocol assessment with the FDA,” Paratek CEO Michael Bigham said in a statement. “Our plan is to submit our NDA in the U.S. as early as the first quarter of 2018 with an EMA submission later in 2018.”

Safety issues appear unlikely to derail omadacycline. Investigators tallied up a lower proportion of drug-related adverse events and discontinuations in the omadacycline arm than the moxifloxacin cohort. Omadacycline was linked to a higher mortality rate than moxifloxacin. But given there was one death in the omadacycline arm in an earlier trial of the drug in skin infections and the 2.1% rate is in line with other pneumonia studies, there is reason to downplay the significance of the finding.