Cempra announced promising data from a Phase 3 trial of oral fusidic acid for the treatment of acute bacterial skin and skin structure infections (ABSSSI).

The Phase 3 study was a randomized, double-blind clinical trial evaluating oral fusidic acid (two loading doses of 1500mg every 12 hours, followed by 600mg every 12 hours) compared to oral linezolid (600 mg every 12 hours) for 10 days in 716 patients with ABSSSI. The primary endpoint was early clinical response (ECR) in the intent to treat (ITT) patient population, defined as the proportion of patients alive and achieving a ≥20% reduction from baseline in lesion size at 48–72 hours after treatment initiation, without receiving rescue antibiotics.

The study achieved its primary endpoint, demonstrating that treatment with oral fusidic acid is non-inferior (10% NI margin) to oral linezolid for ECR in the ITT patient population. In ITT patients treated with fusidic acid, 87.2% achieved ECR compared to 86.6% in the linezolid arm (treatment difference 0.6%, 95% CI: –4.6, +5.9). Fusidic acid also showed comparable efficacy to linezolid in investigator-assessed clinical response in the ITT and clinically evaluable (CE) populations at end-of-treatment (EOT) and post-therapy evaluation (PTE; 7–14 days post-EOT) visits. 

In addition, fusidic acid was found to exhibit strong activity against key gram-positive pathogens, with a microbiological success rate of 100% with methicillin-resistant Staphylococcus aureus (MRSA) infection at both EOT and PTE visits.

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The study also found fusidic acid to be well-tolerated, with rates of treatment-emergent adverse events (TEAEs) comparable to linezolid (37.9% vs. 36.1% respectively). The most common TEAEs in both treatment arms were gastrointestinal events (22.8% fusidic acid vs. 18.2% linezolid). Cempra intends to present detailed results of the study at an upcoming scientific forum.

Fusidic acid is an oral antibiotic with activity against gram-positive bacteria, including more resistant Staphylococcus aureus strains such as healthcare-acquired MRSA and community-acquired MRSA.

For more information visit Cempra.com.