Top-Line Results Show New Antibiotic for CABP Performing Well in Phase 3 Trial

Top-line results released this week on a global phase 3 clinical study revealed that omadacycline, which is a once-daily oral and intravenous (IV) broad-spectrum investigational antibiotic, met all US Food and Drug Administration (FDA) primary and secondary endpoints and European Medicines Agency (EMA) co-primary endpoints. These positive results will move the antibiotic one step closer to a US New Drug Application, which is planned for early in the first quarter of 2018.

According to a press release from Paratek Pharmaceuticals, who developed the antibiotic, omadacycline is “being developed for use as empiric monotherapy for patients suffering from serious community-acquired bacterial infections (CABIs), such as acute bacterial skin and skin structure infections, community-acquired bacterial pneumonia (CABP), urinary tract infections and other community-acquired bacterial infections.” The FDA has already granted omadacycline a Qualified Infectious Disease Product designation and Fast Track status for these target indications.

In the phase 3 double-blind, active-controlled, global, multi-center study, also known as OPTIC (Omadacycline for Pneumonia Treatment in the Community, investigators “compared the safety and efficacy of once-daily, IV-to-oral omadacycline to IV-to-oral moxifloxacin for treating adults with CABP.”

For the study, a total of 774 randomized adult patients, “initially received IV administration of either 100 mg of omadacycline or 400 mg of moxifloxacin. Study investigators were permitted to switch patients to oral dosing of their assigned drug (300 mg once daily omadacycline or 400 mg once daily moxifloxacin) for a total of 7 to 14 days based on assessment of clinical stability.”

The top-line results of the study, released by Paratek this week, show that omadacycline met the following specified endpoints:

• FDA-specified primary endpoint of statistical non-inferiority (NI) in the intent-to-treat (ITT) population (10% NI margin, 95% confidence interval) compared to moxifloxacin at the early clinical response (ECR) 72-120 hours after initiation of therapy. The ECR rates for the omadacycline and moxifloxacin treatment arms were 81.1 % and 82.7%, respectively.
• FDA-specified secondary endpoints of statistical NI at the post-treatment evaluation (PTE) visit 5-10 days after the completion of therapy in both the ITT population (87.6% for omadacycline vs. 85.1% for moxifloxacin) and in the clinically evaluable (CE) population (92.9% for omadacycline vs. 90.4% for moxifloxacin) as determined by investigators.
• Co-primary endpoints for EMA Non-inferiority in the ITT and CE CABP populations in those patients with Pneumonia Severity Index (PORT) III and IV at the PTE time point. High response rate and statistical NI to moxifloxacin for both populations using a prespecified 97.5% confidence interval. High success rates were observed with response rates of 88.4% (omadacycline) vs. 85.2% (moxifloxacin) and 92.5% (omadacycline) vs. 90.5% (moxifloxacin), respectively.

In addition, omadacycline was determined to be generally safe and well-tolerated, which is consistent with prior studies.

More information on the common treatment adverse events for omadacycline, alone, as well as omadacycline compared with moxifloxacin, are available via the press release. The study results will be submitted for presentation at an as-yet-to-be announced scientific congress.

According to the Centers for Disease Control and Prevention, pneumococci account for upwards of 36% of adult community-acquired pneumonia cases. In addition, “bacteremia occurs in up to 25—30% of patients with pneumococcal pneumonia.” Perhaps more alarming, though, is the fact that in about 30% of cases, pneumococcal bacteria are resistant to one or more antibiotics. Although, other broad-spectrum antibiotics such as cephalosporin and vancomycin are often used to treat these infections, it cannot hurt to add another effective ‘gun’ to the arsenal, particularly in light of the resistance to the medications.