# A Novel Approach to Restore Epithelial Barrier Homeostasis to Treat Inflammatory Bowel Disease

> **NIH NIH R44** · THELIUM THERAPEUTICS INC · 2022 · $795,004

## Abstract

SUMMARY
Intestinal barrier function is compromised in enteric and systemic diseases, including infectious
enterocolitis, food allergy, celiac disease, graft versus host disease (GvHD), and inflammatory
bowel disease (IBD). The co-founders of Thelium Therapeutics discovered the central role of
myosin light chain kinase (MLCK) in barrier regulation and demonstrated that targeted intestinal
epithelial MLCK inhibition limits experimental IBD and GvHD. Unfortunately, severe toxicities
associated with barrier-independent MLCK functions in epithelia and other tissues, e.g., smooth
muscle, preclude therapeutic targeting of MLCK enzymatic activity. We recently reported
(Graham et al., Nature Medicine, 2019) that a specific MLCK splice variant, MLCK1, is central to
barrier regulation and depends on interactions mediated by immunoglobulin-cell adhesion
molecule domain 3 (IgCAM3). We solved the IgCAM3 crystal structure, identified a drug binding
pocket unique to IgCAM3, and screened a library of ~140,000 drug-like molecules. Our tool
compound, Divertin, bound IgCAM3, prevented cytokine-induced MLCK1 recruitment, myosin II
regulatory light chain phosphorylation, and barrier dysfunction. Critically, Divertin did not inhibit
MLCK enzymatic function, epithelial wound healing, or smooth muscle contraction, and in vivo
toxicity studies failed to identify adverse effects. Divertin prevented acute TNF-induced barrier
loss in vivo (mice) and ex vivo (human intestinal biopsies), and restored immune-mediated
barrier loss in vivo (IL-10 knockout mice). Finally, Divertin delayed onset and prevented
progression of experimental immune-mediated (T cell transfer) IBD, as indicated by barrier
preservation and restoration, reduced mucosal immune activation, and enhanced survival. In a
Phase I SBIR, we advanced this program through the discovery of hit compounds with improved
activities. Hit compounds were discovered through a rigorous rank order screening funnel to
identify compounds with suitable MLCK1 binding affinities, efficacy in preserving and restoring
epithelial barrier function, and absence of enzymatic inhibitory activity. In this Phase II proposal,
these hit compounds will be optimized with iterative structure activity relationship studies and
tested for toxicity and efficacy in mouse models of IBD. This work will facilitate IND-enabling
studies for a first-in-class and best-in-class barrier-restorative therapy to manage
gastrointestinal and systemic diseases.

## Key facts

- **NIH application ID:** 10484275
- **Project number:** 2R44DK123904-02A1
- **Recipient organization:** THELIUM THERAPEUTICS INC
- **Principal Investigator:** W Vallen Graham
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $795,004
- **Award type:** 2
- **Project period:** 2019-09-15 → 2022-11-15

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10484275

## Citation

> US National Institutes of Health, RePORTER application 10484275, A Novel Approach to Restore Epithelial Barrier Homeostasis to Treat Inflammatory Bowel Disease (2R44DK123904-02A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10484275. Licensed CC0.

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