Acurx Pharmaceuticals, a late-stage biopharmaceutical company developing a new class of antibiotics for difficult-to-treat bacterial infections, has announced that the US Food and Drug Administration (FDA) has conditionally accepted Cifbezy as the proposed proprietary name for ibezapolstat, its lead antibiotic candidate being developed for the acute treatment of Clostridioides Difficile Infection (CDI) and the reduction of disease recurrence.

The company also announced that the US Patent and Trademark Office (USPTO) has allowed its trademark application for Cifbezy. The two milestones address separate regulatory and intellectual-property requirements as Acurx prepares to advance ibezapolstat into international Phase 3 clinical development.

FDA's conditional acceptance of the proposed name is subject to approval of a US New Drug Application (NDA). The proprietary-name review is intended to assess patient safety and minimise the potential for medication errors. Separately, the USPTO's notice of allowance indicates that the Cifbezy trademark has cleared the examination process and opposition period, subject to completion of the remaining registration requirements.

Acurx said securing the proprietary name and trademark protection represents an important preparatory step as it progresses towards potential commercialisation.

The name Cifbezy, pronounced “sif-BEZ-ee”, was developed through a screening process involving external branding specialists, prescribers, pharmacists and linguists. The process was conducted in accordance with FDA requirements and evaluated by the agency's Division of Medication Error Prevention and Analysis (DMEPA), consistent with its guidance for the evaluation of proprietary drug names.

Ibezapolstat is an orally administered antibiotic being developed as a Gram-Positive Selective Spectrum (GPSS) antibacterial. It is the first candidate from Acurx's new class of DNA polymerase IIIC inhibitors under development for bacterial infections.

The candidate is designed to target C. difficile while limiting disruption to other components of the gut microbiome. According to Acurx, its selective spectrum of activity spares other Firmicutes and important Actinobacteria, potentially helping preserve a healthier intestinal microbial environment during treatment.

Ibezapolstat received Qualified Infectious Disease Product (QIDP) designation from the FDA in June 2018 for the treatment of patients with CDI. The designation makes the candidate eligible for certain incentives established under the Generating Antibiotic Incentives Now (GAIN) Act. In 2019, the FDA also granted Fast Track designation to ibezapolstat for the treatment of CDI.

Acurx has completed a Phase 2 clinical programme comprising a multicentre, open-label, single-arm Phase 2a segment followed by a double-blind, randomised, active-controlled, non-inferiority Phase 2b segment conducted across 28 clinical trial sites in the US.

The Phase 2 programme evaluated the clinical efficacy of ibezapolstat in CDI while also assessing pharmacokinetics and changes in the gut microbiome. The programme further examined potential anti-recurrence effects, including changes in microbial diversity, bacterial abundance and bile acid metabolism.

Acurx said findings from its Phase 2 development programme have provided evidence supporting further investigation of ibezapolstat's potential to reduce recurrence while treating the initial infection.

CDI remains a significant healthcare challenge across hospitals, long-term care facilities and community settings. C. difficile can be present in the gut without causing disease, but disruption of the normal intestinal microbiome can allow the organism to proliferate and produce toxins that damage the intestinal lining and trigger inflammation.

Recurrence represents one of the major challenges associated with CDI treatment. The risk can increase among patients who have experienced previous episodes, creating a significant unmet need for therapies capable of both treating the initial infection and reducing the likelihood of recurrence.

According to Acurx, recurrence rates reported in recent studies have ranged from approximately 4 percent to 19.5 percent following fidaxomicin treatment and from 17 percent to 27 percent following vancomycin treatment. Among patients with multiple previous CDI episodes, recurrence following vancomycin treatment can reach approximately 40 percent.

Acurx's development strategy for ibezapolstat is also focused on its potential impact on the gut microbiome. The company believes that limiting disruption of beneficial intestinal bacteria may help preserve the production of secondary bile acids, which play an important role in maintaining resistance to C. difficile recurrence.

Primary bile acids can promote germination of C. difficile spores, while secondary bile acids generated by the normal gut microbiota can inhibit processes associated with recurrent disease. According to Acurx, Phase 2a observations showed changes in bile acid profiles following ibezapolstat treatment, including reductions in primary bile acids and increases in secondary bile acids.

In the Phase 2b trial, the company reported that patients treated with ibezapolstat showed lower concentrations of faecal primary bile acids and a higher secondary-to-primary bile acid ratio compared with patients receiving vancomycin.

These findings are part of the rationale for advancing ibezapolstat into Phase 3 development, where its efficacy, safety and potential impact on CDI recurrence will require confirmation in larger clinical studies.

With the proposed Cifbezy name conditionally accepted by the FDA and the trademark application allowed by the USPTO, Acurx is now progressing towards the next stage of development for ibezapolstat. The company aims to evaluate the antibiotic in international Phase 3 trials as it works towards a potential NDA submission and, subject to regulatory approval, eventual commercialisation.