Acurx Pharmaceuticals Highlights New Data on Ibezapolstat’s Microbiome-Sparing Activity at IDWeek 2025

Acurx Pharmaceuticals, Inc. (NASDAQ: ACXP), a late-stage biopharmaceutical company developing a new class of antibiotics for difficult-to-treat bacterial infections, presented new data on its lead candidate ibezapolstat (IBZ) and preclinical DNA pol IIIC inhibitors at the Infectious Diseases Society of America (IDSA) IDWeek™ 2025 in Atlanta, GA.

Key Findings

• Selective antibacterial activity: Ibezapolstat demonstrated unique, selective action in the gut, targeting C. difficile while sparing beneficial bile acid–metabolizing bacteria.
• Anti-recurrence effect: The resulting favorable bile acid profile contributes to reduced recurrence in C. difficile infection (CDI).
• Potential class effect: Early data from Acurx’s preclinical DNA pol IIIC inhibitors suggest that microbiome selectivity may extend across the class, distinguishing these antibiotics from traditional therapies such as linezolid.

Acurx was one of five companies invited to present during the “New Antimicrobials in the Pipeline” session.

“Our results indicate that the microbiome-sparing effect seen with ibezapolstat may be a class effect,” said Dr. Kevin Garey, Professor and Chair at the University of Houston College of Pharmacy. “This feature likely contributes to ibezapolstat’s sustained efficacy — no recurrence was observed in cured Phase 2 patients.”

Robert J. DeLuccia, Executive Chairman of Acurx, added: “Preserving the healthy microbiome sets this class apart from existing antibiotics. These findings could transform treatment of serious infections caused by Gram-positive pathogens.”

Phase 2 and Phase 3 Development

In Phase 2 trials, 96% of patients with CDI achieved clinical cure with ibezapolstat, and 100% of cured patients remained recurrence-free one month after treatment — compared to 86% in the vancomycin group. The therapy was well-tolerated, with no drug-related serious adverse events reported.

Based on regulatory guidance from both the FDA and EMA, Acurx plans to begin international Phase 3 trials, enrolling roughly 450 subjects across two randomized, controlled studies comparing ibezapolstat with vancomycin.

Scientific Context

Ibezapolstat, a Gram-Positive Selective Spectrum (GPSS®) antibiotic, is the first in a new class of DNA polymerase IIIC inhibitors that block bacterial DNA replication in Gram-positive pathogens. Its microbiome-sparing activity appears linked to increased secondary bile acid production, which is associated with resistance to C. difficile colonization.

The candidate has received both Qualified Infectious Disease Product (QIDP) and Fast Track designations from the U.S. FDA under the GAIN Act.

About Acurx Pharmaceuticals

Acurx is developing DNA pol IIIC inhibitors to address infections caused by Gram-positive priority pathogens, including C. difficile, MRSA, VRE, and B. anthracis. Using AI-driven design tools, the company aims to develop next-generation, microbiome-sparing antibiotics with novel mechanisms of action.

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