Efficacy and Safety of Meropenem–Vaborbactam Versus Best Available Therapy for the Treatment of Carbapenem-Resistant Enterobacteriaceae Infections in Patients Without Prior Antimicrobial Failure: A Post Hoc Analysis

Introduction: Infections due to Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae are associated with increased morbidity and high mortality. Meropenem–vaborbactam (MV) is a novel β-lactam/β-lactamase inhibitor combination active against KPC-producing Enterobacteriaceae. The aim of this post hoc analysis of the TANGO-II randomized controlled trial was to assess the efficacy of MV versus best available therapy (BAT) in the subgroup of patients without prior antimicrobial failure. Methods: The primary outcome measure was clinical cure at the test of cure (TOC). Secondary outcome measures included (1) clinical cure at the end of therapy (EOT), (2) microbiological cure at TOC, (3) microbiological cure at EOT, and (4) 28-day all-cause mortality. Results: First-line MV was associated with a 42.9% absolute increase in clinical cure rate at TOC (95% confidence intervals [CI] 13.7–72.1) in comparison with first-line BAT. A 49.3% absolute increase in clinical cure rate at EOT (95% CI 20.8–77.7), a 42.6% absolute increase in microbiological cure rate at EOT (95% CI 13.4–71.8), and a 36.2% absolute increase in microbiologic cure rate at TOC (95% CI 5.9–66.6) were also observed, in addition to a 29.0% absolute reduction in mortality (95% CI − 54.3 to − 3.7). Overall, fewer adverse events were observed in the MV group than in the BAT group. Conclusion: MV was superior to BAT in the subgroup of patients with serious carbapenem-resistant Enterobacteriaceae (CRE) infections and no prior antimicrobial failure, with very high rates of clinical success, and was well tolerated. Post approval and real-world studies remain essential to clearly define the most appropriate population for early, empirical MV coverage, in accordance with antimicrobial stewardship principles. Funding: The Medicines Company.