Phase III trial of PTK 0796 (omadacycline) in ABSSSI meets primary endpoints- Paratek Pharmaceuticals

Paratek Pharmaceuticals has announced that the Phase III registration study comparing PTK 0796 (omadacycline) to linezolid in the treatment of acute bacterial skin and skin structure infections (ABSSSI) met the FDA-specified primary efficacy endpoint of early clinical response. In addition, the study met the two European Medicines Agency (EMA)-specified co-primary efficacy endpoints for post-treatment evaluation. This positive study is the first of two Phase III registration studies designed to support omadacycline regulatory applications for the FDA and EMA.

In the modified Intent to Treat (mITT) analysis population, omadacycline achieved the primary efficacy endpoint of statistical non-inferiority (10% margin) compared to linezolid. The Early Clinical Response (ECR) for the omadacycline and linezolid treatment arms was 84.8% compared to 85.5%, respectively. Omadacycline was generally safe and well tolerated. Among treatment-emergent adverse events (TEAEs), gastrointestinal events were most common in both treatment groups (18.0% for omadacycline and 15.8% for linezolid): the most common individual TEAEs (at least 3% in either group) included nausea (12.4% vs. 9.9%), vomiting (5.3% vs. 5.0%), and diarrhea (2.2% vs. 3.1%) for omadacycline and linezolid, respectively. Discontinuation for gastrointestinal TEAEs was uncommon. Results of this study, including the results of the secondary endpoints, will be presented at an upcoming scientific congress.

Comment: Novartis had gained exclusive worldwide rights to market PTK 0796, potentially the first once-daily broad-spectrum antibiotic that can be given by intravenous (IV) infusion or oral tablet to treat a wide variety of life-threatening infections, including those caused by highly resistant bacteria such as methicillin-resistant. These rights have since been returned to Paratek due to delays and uncertainties in connection with the regulatory pathway for approval of omadacycline in core indications.