Staten Island, N.Y. – September 17, 2026 -- Acurx Pharmaceuticals (NASDAQ: ACXP) presented new in vitro data showing its lead antibiotic ibezapolstat achieved a 5.51-log reduction against Clostridioides difficile in co-culture with vancomycin-resistant Enterococcus (VRE), significantly outperforming vancomycin (p=0.0112), the current standard of care.
The poster, presented by Dr. Eugenie Bassères of the University of Houston College of Pharmacy, was unveiled at the 9th International C. difficile Symposium in Bled, Slovenia, held September 8-10, 2026.
VRE strains showed high-level resistance to vancomycin but not to ibezapolstat
All tested VRE strains exhibited vancomycin resistance with minimum inhibitory concentrations (MIC) above 128 μg/mL. Ibezapolstat and fidaxomicin maintained equivalent, lower susceptibility thresholds of 2-16 μg/mL.
Enterococcus co-culture cut C. difficile killing by up to 2.90 logs across all antibiotics
Enterococcus created a protective microenvironment that impaired C. difficile eradication regardless of treatment. Ibezapolstat retained the highest residual anti-C. difficile activity among the three agents tested, while vancomycin remained inactive against VRE even when C. difficile was present.
Ibezapolstat showed superior suppression of the VanA resistance gene cluster
At the transcriptional level, all three antibiotics suppressed toxin B (TcdB) gene expression compared to controls. Ibezapolstat demonstrated statistically significant superiority over vancomycin and fidaxomicin in reducing the VanA cluster linked to vancomycin resistance.
Dr. Kevin Garey, Professor and Chair at the University of Houston College of Pharmacy and principal investigator for the ibezapolstat program's microbiology aspects, said the data add to evidence that ibezapolstat kills C. difficile while preserving the microbiome and does not promote VRE overgrowth.
FDA signaled openness to a single Phase 3 trial for NDA submission
Acurx disclosed that a Type C meeting with the FDA on July 13, 2026 addressed the scope of its planned New Drug Application. The agency indicated it would consider an NDA based on a single Phase 3 trial depending on the totality of clinical data, and acknowledged that a successful recurrent CDI (rCDI) trial could support submission.
The planned IBZ-ASPIRE trial is a non-inferiority study enrolling approximately 550 subjects in a modified intent-to-treat population, randomized 1:1 between ibezapolstat and vancomycin. The FDA agreed the design could support indications for both acute treatment and reduction of recurrence of CDI, pending funding. Acurx is separately running IBZ-PATHFINDER, an open-label pilot trial in patients with multiply recurrent CDI who have had at least three episodes within 12 months.
Executive Chairman Robert J. DeLuccia said validation of the co-culture results in the Phase 3 program could position ibezapolstat to reduce hospital-acquired VRE emergence while treating CDI, citing a competitive advantage over vancomycin and fidaxomicin, particularly for reducing recurrence.