Cempra's Fusidic Acid Achieves Primary Endpoint in Phase 3 Study of ABSSSI
today announced positive topline results from a phase 3 study of oral fusidic acid in 716 patients with acute bacterial skin and skin structure infections (ABSSSI). Fusidic acid was well tolerated in the study and achieved the primary endpoint, demonstrating non-inferiority (NI) (10% NI margin) of oral fusidic acid compared to oral linezolid for early clinical response (ECR) in the intent to treat (ITT) patient population
The double-blind study was conducted at 62 sites in the United States. Patients randomized to treatment with oral fusidic acid received a loading dose of 1500 mg every 12 hours for two doses, followed by 600 mg every 12 hours thereafter, until the end of a 10 day course of therapy. Patients randomized to treatment with the active comparator, oral linezolid, received 600 mg every 12 hours for 10 days. Randomization was 1:1 and was stratified by type of infection (cellulitis, wound infection, major cutaneous abscess), by age and by prior use of an antibiotic within 36 hours prior to randomization
Strong Activity Against Key Pathogens, Including MRSA
Microbiological response rates by pathogen were high in both treatment groups in both the microbiological ITT (mITT) and microbiologically-evaluable (ME) patient populations (patients with isolation of a baseline pathogen, who were also clinically evaluable). The most common pathogens identified were Staphylococcus aureus, Streptococcus anginosus group species, Streptococcus pyogenes and Clostridium species. Notably, the microbiological success rate among fusidic acid recipients in each ME population with methicillin-resistant S. aureus (MRSA) infection was 100 percent (99/99) at both the EOT and PTE visits.
Fusidic Acid Well Tolerated
Fusidic acid was well tolerated in the study. The rates of treatment-emergent adverse events (TEAEs) were comparable between treatment groups (37.9 percent fusidic acid, 36.1 percent linezolid). The most common TEAEs in both treatment groups were gastrointestinal events (22.8 percent fusidic acid, 18.2 percent linezolid). Serious adverse events (SAEs) occurred in six fusidic acid recipients and eight linezolid recipients, and were considered study-drug related in one fusidic acid recipient (vomiting) and in two linezolid recipients (one drug induced liver injury, one vomiting). Adverse events led to study drug discontinuation in 2.2 percent of fusidic acid recipients, and 2.0 percent of linezolid recipients. There was one death in the study, an event due to illicit drug overdose and aspiration which occurred in a patient receiving linezolid. Rates of treatment-emergent ALT elevation to >3x ULN occurred in 1.0 percent of fusidic acid recipients and 0.7 percent of linezolid patients.
"Considering complicated skin infections are one of the most rapidly growing reasons for hospitalizations and emergency department visits each year, the results with fusidic acid in this study are promising, especially for an outpatient population where there is a need for new oral drugs that are effective against MRSA," said William O'Riordan, M.D., chief medical officer of eStudySite, leaders in evaluating new therapeutic approaches for complicated skin infections
