Staten Island, New York, August 3, 2026
Acurx Pharmaceuticals, Inc. announced further regulatory guidance from the U.S. Food and Drug Administration (FDA) regarding the Phase 3 clinical development program for ibezapolstat, its investigational oral antibiotic for Clostridioides difficile infection (CDI). The guidance follows a Type C Meeting conducted with the FDA on July 13, 2026, and includes the potential for Acurx to pursue a New Drug Application (NDA) supported by a single Phase 3 trial, depending on the totality and robustness of clinical evidence generated by the program. The FDA also agreed with a trial strategy that, if successful, could support indications covering both acute treatment of CDI and reduction of CDI recurrence, providing Acurx with greater clarity as it prepares its late-stage development strategy.
FDA Opens Path to Potential Single Phase 3 Trial NDA
The FDA indicated it would be open to further discussion at a pre-NDA meeting regarding the possibility of an NDA based on one Phase 3 trial, following completion of the planned study and consideration of other supportive clinical evidence. The Agency emphasized that acceptance of a single pivotal trial is determined case by case and would depend on factors including the magnitude, consistency and robustness of efficacy results, applicability to the U.S. patient population, relevance to clinical practice, Phase 2 evidence and an adequate safety database. Acurx’s planned IBZ-ASPIRE Phase 3 trial will use a non-inferiority design and is expected to include approximately 550 patients in the modified intent-to-treat population, randomized 1:1 to receive either ibezapolstat or standard-of-care vancomycin. If non-inferiority for clinical cure is established, additional analyses are planned to evaluate superiority in reducing recurrence and clinical cure. If the evidence does not satisfy FDA expectations for a single-trial submission, a second Phase 3 study would be recommended.
Ibezapolstat Targets Treatment and Recurrence of C. difficile
The FDA also agreed that a successful outcome from IBZ-ASPIRE, supported by the open-label IBZ-PATHFINDER Phase 2 study in multiply recurrent CDI, could allow Acurx to file an NDA seeking indications for both acute treatment and reduction of recurrence. Start-up activities for IBZ-PATHFINDER are underway, with enrollment expected to begin in the coming months. The pilot study will enroll 20 patients with multiply recurrent CDI who have experienced at least three episodes during the previous 12 months. The findings are intended to support the recurrence indication and inform a future active-controlled Phase 3 registration trial. Ibezapolstat is a novel, orally administered Gram-Positive Selective Spectrum antibacterial and the first of a new class of DNA polymerase IIIC inhibitors being developed by Acurx. Its targeted activity against C. difficile while sparing important components of the gut microbiome could potentially contribute to reduced recurrence, although this will require confirmation through ongoing clinical development.
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Acurx Prepares Ibezapolstat for International Phase 3 Development
Acurx is positioned to initiate the international IBZ-ASPIRE Phase 3 program, subject to funding availability, building on previously completed Phase 2 development. Earlier studies evaluated ibezapolstat’s clinical efficacy, pharmacokinetics and effects on the gut microbiome and bile acid metabolism. Maintaining a healthier microbiome may be particularly relevant in CDI because disruption of normal intestinal bacteria can contribute to disease recurrence. Recurrent CDI remains a significant unmet medical need, with recurrence rates reported by Acurx ranging from 17% to 27% following vancomycin treatment and reaching up to 40% among patients with multiple previous CDI episodes. Ibezapolstat has already received FDA Qualified Infectious Disease Product (QIDP) and Fast Track designations, while Acurx has received Small and Medium-sized Enterprise designation from the European Medicines Agency. The latest FDA guidance provides an important regulatory framework for the company as it moves toward pivotal development and a potential NDA. If the planned clinical studies generate sufficiently robust efficacy and safety evidence, the program could support a differentiated antibiotic strategy addressing both initial C. difficile infection and the persistent challenge of disease recurrence, while potentially creating a more streamlined regulatory pathway for ibezapolstat.
Source: Acurx Pharmaceuticals press release
