# Evidentiary Standards for Newly Approved Antibiotics for Uncomplicated Urinary Tract Infections

## TL;DR

This paper evaluates the evidence behind two new antibiotics approved for treating uncomplicated urinary tract infections, finding limitations in their clinical trial designs and outcomes.

## Contribution

The study critically analyzes the regulatory evidence and trial designs for two newly approved antibiotics, highlighting gaps in their clinical relevance.

## Key findings

- Sulopenem/probenecid was noninferior to amoxicillin/clavulanate but inferior to ciprofloxacin in treating susceptible pathogens.
- Gepotidacin showed noninferiority to nitrofurantoin in one trial and superiority in another.
- Both new antibiotics had higher adverse event rates and lower cure rates than historical standards.

## Abstract

Importance: Uncomplicated urinary tract infections (uUTIs) are among the most common bacterial infections and are typically treated with existing oral antibiotics. In 2024–2025, the FDA approved two new oral agents, sulopenem etzadroxil/probenecid and gepotidacin, via expedited review pathways, for the treatment of uUTIs. Objective: To assess the clinical significance and regulatory evidence supporting FDA approval of sulopenem/probenecid and gepotidacin for uUTI, and to analyze the adherence of pivotal phase III trials to regulatory standards for approval and FDA guidelines. Design, Setting, and Participants: Comparative descriptive analysis of publicly available data from phase 3 randomized, double-blind, active-controlled clinical trials submitted to the FDA for approval. Pivotal phase III clinical trial data and FDA integrated reviews, guidance for the industry, and approved drug labels. Adult women with uUTI enrolled in pivotal phase III clinical trials, with subgroup analysis stratified by pathogen susceptibility to comparator antibiotics. Interventions: Sulopenem/probenecid was compared to ciprofloxacin and to amoxicillin/clavulanate and gepotidacin was compared to nitrofurantoin. Main Outcomes and Measures: Primary endpoints were clinical and microbiological responses assessed in the microbiologic modified intention-to-treat (micro-MITT) subjects. Safety outcomes and FDA regulatory determinations were also assessed. Results: Sulopenem/probenecid was inferior to ciprofloxacin and noninferior to amoxicillin/clavulanate in subjects with susceptible pathogens, and superior in subjects with resistant pathogens. Gepotidacin showed noninferiority to nitrofurantoin in one trial and superiority in another. Trials excluded randomized subjects, included post-randomization subgroup analyses, and enrolled control-arm subjects with resistant pathogens. Clinical cure rates were lower than historical comparators. Both new antibiotics had higher adverse event rates than controls. Conclusions and Relevance: Pivotal clinical trials for sulopenem/probenecid and gepotidacin for uUTI had significant design limitations and relied on surrogate endpoints of limited clinical interpretability, undermining reliability and clinical relevance. Future antibiotic development for uUTI should prioritize representative populations, standard-of-care comparators, clinically meaningful outcomes and robust, well-controlled trial designs to ensure meaningful clinical evidence of safety and efficacy.