# Oral Protein Therapeutics Against C. difficile Associated Colitis

> **NIH NIH R56** · TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR · 2021 · $747,660

## Abstract

Abstract
Each year, Clostridium difficile (C. difficile), a Gram-positive, spore-forming anaerobic bacillus, causes over a
quarter million infections, ~15,000 deaths and over $1 billion in treatment-associated costs. The symptoms of
C. difficile infection (CDI) ranges from mild cases of diarrhea to fatal pseudomembranous colitis. Although
primary CDI can generally be treated with antibiotics, over the past decades, the rate of CDI recurrence has
greatly increased due to the emergence of antibiotic-resistant and so-called hypervirulent strains (20-25%
relapse). C. difficile secreted toxin A (TcdA) and toxin B (TcdB) are the critical virulence factors that cause a
range of diseases collectively designated as CDI. The most recently FDA approved CDI therapeutic –
ZINPLAVA (bezloxumab, an intravenously administered anti-TcdB monoclonal antibody to be used concurrent
with antibiotics) – was found to reduce the rate of recurrence but neither lessen the severity nor shorten the
duration of CDI. Thus, more effective therapies against CDI are still urgently needed. Since C. difficile and its
secreted toxins reside within the gastrointestinal (GI) tract, a location not easily accessible by i.v.-administered
antibodies, we hypothesize that an oral toxin-neutralizer should be more effective at preventing CDI
pathogenesis. Previously, anti-toxin hyperimmune bovine colostrum (HBC) has been demonstrated as an
effective oral therapeutic for treating and/or preventing various viral and bacterial GI infections, setting a
precedent for oral anti-toxin protein therapeutics against CDI. Recently, our lab engineered a panel of designed
ankyrin repeat protein (DARPin) with potent neutralization activity against TcdB. The DARPin protein scaffold
was further engineered to render it highly resistant to digestion by GI-resident proteases while retaining its
toxin-neutralization ability. In this project, we intend to further evaluate the therapeutic potential of DARPins
against CDI. Specifically, in Aim 1, to facilitate more effective in situ delivery of anti-toxin DARPins to the
colon, lead probiotic strains will be created for DARPin secretion. In Aim 2, for patients with severely
compromised immune system and unfit for receiving live microorganisms, an alternative cecum/colon protein
delivery strategy will be explored. Concurrently, additional DARPins will be engineered to target highly
conserved domains on TcdA and TcdB (Aim 3). Successful completion of the proposed study will yield anti-
toxins as potential next-generation oral therapeutics against CDI. In addition, this study may establish a new
oral therapeutic paradigm for other enteric diseases.

## Key facts

- **NIH application ID:** 10455793
- **Project number:** 1R56AI155917-01A1
- **Recipient organization:** TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
- **Principal Investigator:** Zhilei Chen
- **Activity code:** R56 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $747,660
- **Award type:** 1
- **Project period:** 2021-09-01 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10455793

## Citation

> US National Institutes of Health, RePORTER application 10455793, Oral Protein Therapeutics Against C. difficile Associated Colitis (1R56AI155917-01A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10455793. Licensed CC0.

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