Delafloxacin vs. Vancomycin Compared for ABSSSI Treatment

NEW ORLEANS, LA—An age- and gender-based pooled analysis presented at IDWeek 2016 showed that delafloxacin had comparable outcomes to vancomycin at 48-72 hours for the treatment of acute bacterial skin and skin structure infections (ABSSSI). 

Delafloxacin, a novel investigational anionic fluoroquinolone antibiotic, is under development for oral or intravenous (IV) administration for infections caused by susceptible Gram-positive organisms, Gram-negative organisms, atypical organisms, and anaerobes.

Laura Lawrence, BS, from Melinta Therapeutics, New Haven, CT, and other study authors reviewed pooled data on age and gender from 2 randomized, double-blind trials of adults with ABSSSI. Patients had wounds, burns, major cutaneous abscesses, or cellulitis ≥75cm² in size and at least 2 systemic signs of infections.

Study patients in North America, Asia, Europe, and Latin America were given delafloxacin 300mg IV twice daily for 5–14 days (Study 1) or for 3 days with a mandatory blinded switch in all patients to 450mg orally twice daily (Study 2) or vancomycin 15mg/kg with aztreonam for 5–14 days.

Both studies had endpoints for objective response at 48–72 hours based on a ≥20% reduction in lesion size and investigator-assessed response rates based on complete resolution of signs and symptoms (“Cure”) at Follow-Up (Day 14) and Late Follow-Up (Day 21–28).

Both groups received a median of 6.0 days of therapy and overall, 85% completed the study through the Late Follow-Up visit.

Among the combined patients (n=1,510) in the intent-to-treat group, cellulitis (44%) was the most common, followed by wound infection (30.1%), major cutaneous abscess (25.1%), and burn infection (0.8%). 

At 48–72 hours in the intent-to-treat group, 81.3% of patients treated with delafloxacin achieved an objective response vs. 80.7% of patients in the vancomycin/aztreonam group (treatment difference 0.8, 95% CI: -3.2, 4.7). Investigator-assessed cure rates for all patients at Follow Up (delafloxacin 55.2%, vancomycin 55.7%) and Late Follow Up (delafloxacin 69.0%, vancomycin 69.0%) were similar, including by age and gender subgroup.

The percent of patients with treatment emergent adverse events, regardless of causality, “was comparable between treatment arms overall and in both age and gender subgroups,” Lawrence noted. Nausea, pruritus, and diarrhea were the most common treatment-related adverse events.

“Nausea, vomiting, and headache were slightly higher in both treatment groups for females compared to males,” she added, while those in the vancomycin/aztreonam arm had slightly higher rates of discontinuation due to adverse events compared with delafloxacin overall as well as for each age subgroup and gender group.