# A Novel Engineered Probiotic for the Prevention of Clostridium Difficile Infection

> **NIH NIH R44** · RISE THERAPEUTICS, LLC · 2021 · $913,769

## Abstract

Project Summary
The goal of this project is to develop a novel drug, R-4329, for prevention of Clostridium (C.) difficile infection
(CDI). R-4329 is a probiotic engineered to recombinantly express and orally deliver a unique microbial protein
known as secreted antigen A (SagA) which our team showed can protect against multiple enteric infections,
including C. difficile, by enhancing the integrity/functionality of the gut membrane barrier1, 2.
C. difficile is a ubiquitous anaerobic Gram-positive bacterium that can sporulate and become highly resistant to
environment stresses and frontline antibiotics such as clindamycin7. Pathogenic strains of C. difficile secret
toxins (A and B) that damage intestinal epithelial cells, resulting in inflammatory colitis, severe diarrhea,
abdominal pain, flu-like symptoms, and possible death7. C. difficile infection (CDI) often occurs following
antibiotic-treatment when the endogenous microflora of individuals is altered or severely reduced. Since 2000,
the rate of CDI has increased from below 150,000 to over 250,000 cases and has been become one of the
most significant hospital-acquired infections with an economic burden of over $1 billion to treat in the U.S.7.
Once C. difficile establishes residence in the colon, it is difficult to eradicate with last resort antibiotics
(vancomycin) and consequently results in lifelong relapses of CDI and inflammatory colitis. An effective
approach to treating CDI has been fecal microbiota transplant (FMT) therapy but this approach is
heterogeneous and a poorly defined therapeutic, for which its safety is still a concern requiring special FDA
approval8. New and well-defined therapeutics are desperately needed to prevent and treat recurrent CDI.
Oral probiotics offer an exciting alternative to manage CDI and strains of Lactobacillus (acidophilus, casei,
reuteri, plantarum) have been explored to inhibit enteric pathogen infection and mitigate antibiotic-associated
diarrhea9. Unfortunately, mechanism of action has been difficult to understand with modest beneficial effects in
the context of their clinical utility10. However, these recent studies suggest that improved probiotics with
directed and targeted anti-infective functionality may be useful at controlling CDI. Indeed, our recent results
published in the journal Science demonstrate that engineering or ‘reprogramming’ of probiotics to
recombinantly express SagA yields a more protective functionality against enteric infections, including CDI2.
Our goal is to develop a novel probiotic strain to deliver recombinant SagA (referred to as R-4329) as an orally
administered drug that functions naturally to induce protective regulatory signals. This Phase II SBIR
application is intended to build upon success and advance R-4329 towards clinical testing. The specific aims
are: 1) optimize R-4329 upstream process development and create a GMP master cell bank, 2) manufacture
R-4329 and develop GLP analytical product release/stability assays...

## Key facts

- **NIH application ID:** 10198740
- **Project number:** 5R44AI152670-02
- **Recipient organization:** RISE THERAPEUTICS, LLC
- **Principal Investigator:** Gary Fanger
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $913,769
- **Award type:** 5
- **Project period:** 2020-07-01 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10198740

## Citation

> US National Institutes of Health, RePORTER application 10198740, A Novel Engineered Probiotic for the Prevention of Clostridium Difficile Infection (5R44AI152670-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10198740. Licensed CC0.

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