1521. Heterogeneity of Recent Phase 3 cUTI Clinical Trials with New Antibiotics

BACKGROUND: For new antibiotics to treat Gram-negative infections, one regulatory pathway includes complicated urinary tract infections (cUTI) clinical trials. Although individual clinical trials comply with regulatory guidelines, they may differ substantially in design and execution. Six recent cUTI trials that supported or are likely to support FDA regulatory review were compared to determine variables that impacted patient selection and outcome parameters. METHODS: cUTI trials for six new antibiotics developed to treat multi-drug-resistant Gram-negative infections were obtained from publicly disclosed information including FDA documents, publications, or presentations at scientific meetings. Antibiotics included were: ceftolozane-tazobactam (CTL-TAZ), ceftazidime–avibactam (CTZ-AVI), meropenem-vaborbactam (MER-VAB), cefiderocol, plazomicin, and fosfomycin. Comparison variables included: mMITT sample size, age, % female patients, % acute pyelonephritis, % E. coli and other pathogens at baseline, switch to PO antibiotic, and the non-inferiority margin. Other variables as well as the microbiologic eradication, clinical response, and the combined outcomes will be included in the poster. RESULTS: CONCLUSION: Study design and eligibility criteria significantly influences patient characteristics. The proportion of acute pyelonephritis varied greatly and influenced population demographics (age, gender) and baseline microbiology. Studies with a smaller proportion of acute pyelonephritis resulted in an older patient population, fewer females and less E. coli. Larger sample size did not impact outcomes. DISCLOSURES: A. Bass, Shionogi Inc.: Employee, Salary. R. Echols, Shionogi Inc.: Consultant, Consulting fee. S. Portsmouth, Shionogi Inc: Employee, Salary. A. Howell, Shionogi Inc.: Employee, Salary.