1477. A Randomized Phase 2 Study of Cefepime Combined with the Novel Extended Spectrum β-Lactamase Inhibitor Enmetazobactam in Hospitalized Adults with Complicated Urinary Tract Infections (cUTI) Including Acute Pyelonephritis (AP)

BACKGROUND: Third-generation cephalosporin (3GC)-resistant Enterobacteriaceae has been classified as critical priority pathogens. The novel extended-spectrum β-lactamase (ESBL) inhibitor enmetazobactam (formerly AAI101; EMT) in combination with cefepime (FEP) is currently being developed as a carbapenem-sparing treatment of serious Gram-negative infections in settings with a high prevalence of 3GC-resistant Enterobacteriaceae. We report here the results from a phase 2 study that assessed safety, tolerability, and pharmacokinetics of FEP-EMT in patients with cUTI/AP. METHODS: Forty-five patients were enrolled in a randomized, multicenter, double-blind study of hospitalized adults with cUTI/AP. Patients received dosing regimens of FEP or FEP-EMT IV therapy q8h by 2 hours infusion (table) for 7 to 10 days with a 28-day follow-up. Efficacy was evaluated in the microbiological-modified ITT (µMITT) population. Safety was monitored in patients who received at least 1 dose of study drug. Clinical cure was designated as the resolution of cUTI symptoms present at study entry. Plasma and urine PK were determined from all patients. RESULTS: The study drugs were well tolerated in each cohort, with similar % adverse events and no new or unexpected safety concerns (table). Two discontinuations were due to allergic dermatitis. The microbiological- and clinical responses at test-of-cure for the combined FEP-EMT group were 83.3% (20/24) and 95.8% (23/24) compared with responses in the combined FEP group of 73.3% (11/15) and 93.3% (14/15), respectively (table). The most common baseline pathogens were Escherichia coli (66.7%) and Klebsiella pneumoniae (23.1%): 28.2% of isolates produced ESBLs with eradication rates for the combined FEP-EMT group of 85.7% (6/7) and for the combined FEP group of 75.0% (3/4). FEP and EMT PK were best described by a 2-compartment, linear PK model. Both agents exhibited half-lives of 2.3 hours. Creatinine clearance had a significant covariate effect on FEP and EMT, consistent with predominant renal excretion of both agents. CONCLUSION: Results from this phase 2 study justify advancement to phase 3 studies to evaluate the safety and efficacy of FEP-EMT in patients with cUTI/AP. DISCLOSURES: All authors: No reported disclosures.