FDA Provides Further Regulatory Guidance to Acurx Pharmaceuticals for the Ibezapolstat Clinical Development Program, Including the Potential for a Single-Phase 3-Trial Registration Plan and a Trial Design to Support Both Treatment and Reduction of Recurrence of C. difficile Infection
Rhea-AI Summary
Acurx Pharmaceuticals (NASDAQ: ACXP) reported that following a July 13, 2026 FDA Type C Meeting, the Agency indicated it is open to considering a single Phase 3 trial (IBZ-ASPIRE) plus supportive data as the basis for an NDA for ibezapolstat in Clostridioides difficile infection (CDI), depending on the overall strength, consistency, and safety of the clinical results.
The FDA agreed that the planned ~550-patient, non-inferiority IBZ-ASPIRE trial, comparing ibezapolstat with vancomycin, could, if successful, support indications for both acute treatment and reduction of recurrence of CDI. FDA also stated that positive data from the open-label IBZ-PATHFINDER Phase 2 rCDI trial would support the NDA. If single-trial criteria are not met, FDA recommends a second Phase 3 study per the earlier EOP2 agreement. Acurx has initiated start-up for IBZ-PATHFINDER and is positioned to begin the international IBZ-ASPIRE trial, subject to funding, and continues to benefit from FDA QIDP and Fast-Track designations and EMA SME status.
Positive
- Potential single Phase 3 registration path may reduce time and cost to NDA
- IBZ-ASPIRE Phase 3 design could support both treatment and recurrence reduction indications
- Approximately 550-patient global Phase 3 trial agreed in principle with FDA
- QIDP and Fast-Track designations support expedited ibezapolstat development
- IBZ-PATHFINDER rCDI trial may provide supportive data for recurrence indication
Negative
- Single-trial NDA path not guaranteed; FDA may still require a second Phase 3
- IBZ-ASPIRE Phase 3 start remains subject to securing adequate funding
- Regulatory acceptance depends on robust efficacy, safety, and generalizability criteria being met
News Explained
The planned IBZ-ASPIRE trial remains subject to funding availability; at
Sources and calculations
- Acurx FDA regulatory guidance press release (2026-08-03)
- Acurx first-quarter 2026 fundamentals (2026Q1)
- Cash and equivalents vs quarterly operating cash outflow, in days of cash use $9,254,813 / ($1,407,533 / 90) = [object Object]
Key Figures
Previous Clinical trial Reports
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| Mar 09 | Recurrent CDI trial | Positive | +44.8% | New recurrent-CDI pilot trial and planned Phase 3 program announcement |
| Jun 17 | Phase 2 clinical data | Positive | +167.2% | Lancet Microbe publication reported Phase 2b efficacy and recurrence findings |
| Jan 06 | Phase 3 regulatory guidance | Positive | +22.5% | EMA guidance supported advancing ibezapolstat into Phase 3 trials |
| Nov 18 | Phase 2 clinical data | Positive | -1.2% | Symposium presentation updated Phase 2b microbiome and clinical data |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Clinical-trial-tagged announcements were usually followed by positive 24-hour reactions, with one divergence; the matched average move was 58.35%.
Key Terms
nda regulatory
non-inferiority medical
modified intent-to-treat medical
pharmacokinetics medical
qidp regulatory
fast track designation regulatory
AI-generated analysis. How Rhea-AI works. Not financial advice.
- Acurx has received FDA guidance in meeting minutes from a July 13, 2026 Type C Meeting to discuss ibezapolstat's (IBZ) Phase 3 clinical program, including the potential to submit an NDA (New Drug Application) based on a single Phase 3 trial and a clinical trial design intended to support indications for both treatment and reduction of recurrence of Clostridioides difficile infection (CDI)
- FDA stated that it is open to further discussion on the totality of evidence from the clinical development program at a pre-NDA meeting after completion of a single Phase 3 trial and any other clinical trials conducted prior to the pre-NDA meeting, particularly if the clinical efficacy results are robust
- Additionally, the Agency agreed that a successful clinical outcome from a single IBZ-ASPIRE Phase 3 trial, supported by the open-label IBZ-PATHFINDER Phase 2 trial in multiply-recurrent CDI (rCDI) will allow NDA filing for both the acute treatment and the reduction of recurrence of CDI
- Trial start-up activities for the IBZ-PATHFINDER ground-breaking clinical trial in patients with rCDI have been initiated with patient enrollment to begin in the next few months
- Acurx is well positioned to commence its international Ph3 IBZ-ASPIRE trial, subject to funding availability
- Acurx has previously been granted FDA QIDP and Fast-Track Designation and has received SME (Small and Medium-sized Enterprise) designation by the EMA
The currently planned IBZ-ASPIRE trial is of non-inferiority design with the primary efficacy analysis in the Modified Intent-To-Treat (mITT) population. This will result in approximately 550 subjects in the mITT population, randomized in a 1:1 ratio to either ibezapolstat or standard-of-care vancomycin. The Agency also agreed with the overall trial design and evaluation criteria and further agreed that the trial testing criteria, if successful, could support indications for both the acute treatment and the reduction of recurrence of CDI. In the event non-inferiority of ibezapolstat to vancomycin for Clinical Cure of CDI is demonstrated, further analyses will be conducted to test for superiority for reduction of recurrence and for clinical cure of CDI.
Robert J. DeLuccia, Executive Chairman of Acurx, stated: "We are very pleased with the guidance and support received from FDA for continued development of ibezapolstat toward a potential NDA." He further stated: "We're confident that if we successfully meet the IBZ-ASPIRE trial endpoints, approval for both treatment and reduction of recurrence is possible based on a single Phase 3 trial. The results from IBZ-PATHFINDER will be important data to support the indication for reduction of recurrence."
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Acurx previously announced that it is conducting a new clinical trial (IBZ-PATHFINDER) in patients with multiply recurrent C. difficile Infection (rCDI) while its program in the broader CDI patient population is ready to advance to Phase 3 international clinical trials (IBZ-ASPIRE), subject to receiving appropriate funding. This new IBZ-PATHFINDER clinical trial in rCDI involves an open-label pilot trial to gain experience with IBZ in patients with multiply-recurrent CDI with at least 3 episodes of CDI within the past 12 months.
About the Ibezapolstat Phase 2 Clinical Trial
The completed multicenter, open-label single-arm segment (Phase 2a) study was followed by a double-blind, randomized, active-controlled, non-inferiority, segment (Phase 2b) at 28 US clinical trial sites which together comprise the Phase 2 clinical trial. (see https://clinicaltrials.gov/ct2/show/NCT04247542). This Phase 2 clinical trial was designed to evaluate the clinical efficacy of ibezapolstat in the treatment of CDI including pharmacokinetics and microbiome changes from baseline and continue to test for anti-recurrence microbiome properties seen in the Phase 2a trial, including the treatment-related changes in alpha diversity and bacterial abundance and effects on bile acid metabolism. (Data published in Lancet, August 2025 https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(25)00054-0/fulltext).
About Ibezapolstat
Ibezapolstat is the Company's lead antibiotic candidate planning to advance to international Phase 3 clinical trials to treat patients with C. difficile infection. Ibezapolstat is a novel, orally administered antibiotic, being developed as a Gram-Positive Selective Spectrum (GPSS®) antibacterial. It is the first of a new class of DNA polymerase IIIC inhibitors under development by Acurx to treat bacterial infections. Ibezapolstat's unique spectrum of activity, which includes C. difficile but spares other Firmicutes and the important Actinobacteria phyla, appears to contribute to the maintenance of a healthy gut microbiome.
In June 2018, ibezapolstat was designated by the
About Clostridioides difficile Infection (CDI) and Recurrent CDI (rCDI)
According to the 2017 Update (published February 2018) of the Clinical Practice Guidelines for C. difficile Infection by the Infectious Diseases Society of America (IDSA) and Society or Healthcare Epidemiology of America (SHEA), CDI remains a significant medical problem in hospitals, in long-term care facilities and in the community. C. difficile is one of the most common causes of health care-associated infections in
In recent studies, rCDI ranges from
About the Microbiome in C. difficile Infection (CDI) and Bile Acid Metabolism
C. difficile can be a normal component of the healthy gut microbiome, but when the microbiome is thrown out of balance, the C. difficile can thrive and cause an infection. After colonization with C. difficile, the organism produces and releases the main virulence factors, the two large clostridial toxins A (TcdA) and B (TcdB). (Kachrimanidou, Microorganisms 2020, 8, 200; doi:10.3390/microorganisms8020200.) TcdA and TcdB are exotoxins that bind to human intestinal epithelial cells and are responsible for inflammation, fluid and mucous secretion, as well as damage to the intestinal mucosa.
Bile acids perform many functional roles in the GI tract, with one of the most important being maintenance of a healthy microbiome by inhibiting C. difficile growth. Primary bile acids, which are secreted by the liver into the intestines, promote germination of C. difficile spores and thereby increase the risk of recurrent CDI after successful treatment of an initial episode. On the other hand, secondary bile acids, which are produced by normal gut microbiota through metabolism of primary bile acids, do not induce C. difficile sporulation and therefore protect against recurrent disease. Since ibezapolstat treatment leads to minimal disruption of the gut microbiome, bacterial production of secondary bile acids continues which may contribute to an anti-recurrence effect. Beneficial effects of bile acids include a decrease in primary bile acids and an increase in secondary bile acids in patients with CDI, which was observed in the Company's Ph2a trial results and previously reported (CID, 2022). In the Ph2b trial, ibezapolstat-treated patients showed lower concentrations of fecal primary bile acids, and higher beneficial ratio of secondary to primary bile acids than vancomycin-treated patients.
About Acurx Pharmaceuticals, Inc.
Acurx Pharmaceuticals is a late-stage biopharmaceutical company focused on developing a new class of small molecule antibiotics for difficult-to-treat bacterial infections. The Company's approach is to develop antibiotic candidates with a Gram-positive selective spectrum (GPSS®) that blocks the active site of the Gram-positive specific bacterial enzyme DNA polymerase IIIC (pol IIIC), inhibiting DNA replication and leading to Gram-positive bacterial cell death. Its R&D pipeline includes antibiotic product candidates that target Gram-positive bacteria, including Clostridioides difficile, methicillin- resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus (VRE), drug- resistant Streptococcus pneumoniae (DRSP) and B. anthracis (anthrax; a Bioterrorism Category A Threat-Level pathogen). Acurx's lead product candidate, ibezapolstat, for the treatment of C. difficile Infection is preparing to advance into international Phase 3 trials.
Additionally, the Company has initiated start-up activities for a ground-breaking clinical trial in patients with rCDI with the first patient expected to enroll in the fourth quarter this year. This trial is a 20-patient, open-label pilot trial in patients with multiply-recurrent CDI with at least 3 episodes of CDI in the past year and will inform elements of a planned active-controlled, Phase 3 registration trial in the rCDI. Upon subsequent successful completion of a Ph3 pivotal rCDI trial, and per the operative FDA procedure, Acurx plans to request FDA approval for treatment and prevention of rCDI under the FDA's Limited Population Pathway for Antibacterial and Antifungal Drugs (Guidance for Industry, 2020). Successful trial outcome has the potential to shift the paradigm of treatment and prevention of rCDI from two agents to one.
The Company's preclinical pipeline includes development of an oral product candidate for treatment of ABSSSI (Acute Bacterial Skin and Skin Structure Infections), upon which a development program for post-exposure prophylaxis of inhalation anthrax is being planned in parallel.
Learn more about Acurx Pharmaceuticals and its product pipeline, please visit www.acurxpharma.com
Forward-Looking Statements
Any statements in this press release about our future expectations, plans and prospects, including statements regarding our strategy, future operations, prospects, plans and objectives, and other statements containing the words "believes," "anticipates," "plans," "expects," and similar expressions, constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: whether ibezapolstat will benefit from the QIDP designation; whether ibezapolstat will advance through the clinical trial process on a timely basis; whether the results of the clinical trials of ibezapolstat will warrant the submission of applications for marketing approval, and if so, whether ibezapolstat will receive approval from the FDA or equivalent foreign regulatory agencies where approval is sought; whether, if ibezapolstat obtains approval, it will be successfully distributed and marketed; and other risks and uncertainties described in the Company's quarterly report on Form 10-Q for the quarter ended March 31, 2026, as filed with the Securities and Exchange Commission on May 12, 2026, and in the Company's subsequent filings with the Securities and Exchange Commission. Such forward- looking statements speak only as of the date of this press release, and Acurx disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances after the date of such statements, except as may be required by law.
Investor Contact:
Acurx Pharmaceuticals, Inc.
David P. Luci, President & CEO
Tel: 917-533-1469
Email: davidluci@acurxpharma.com
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