Paratek Antibiotic Hits Endpoints in Phase 3, Teeing Up NDA

Paratek is planning to submit an application in the first quarter of 2018

A phase 3 trial of an oral formulation of Paratek Pharmaceuticals’ antibiotic omadacycline has met its primary endpoints, FierceBiotech reports. The third late-phase success for omadacycline sets Paratek up to file for approval with the FDA, although incidence of vomiting and nausea cast a shadow over the data.

Investigators enrolled 735 adults with acute bacterial skin and skin structure infections (ABSSSI) in the trial and randomized them to receive either omadacycline once a day or linezolid twice a day. The study assessed noninferiority two to three days after the first dose for the FDA.

Omadacycline held its own against linezolid by either yardstick. In the first days after treatment 87.5% patients in the omadacycline cohort responded, compared to 82.5% in the control arm. That resulted in success against the FDA endpoint.

The data mark the first time a pivotal trial has shown an oral-only regimen of omadacycline has comparable efficacy to established antibiotics. Two earlier phase 3 trials in ABSSSI and community-acquired bacterial pneumonia (CABP) also met their primary endpoints. But patients in those trials started on an IV formulation of omadacycline before transitioning to the oral version.

While the efficacy data for the oral-only regimen held up, its side effect profile was worse than that generated in the earlier studies. Almost one-third of participants in the omadacycline arm suffered from nausea, compared to 7.6% in the control cohort. And 16.8% of people who took the study drug experienced vomiting, compared to 3% who received linezolid.

The rates of nausea and vomiting are notably higher than was seen in the two earlier phase 3 trials. Paratek sought to downplay the emergence of the adverse event, noting most cases occurred on the first two days of treatment and were short lived.

Source: FierceBiotech; July 18, 2017.