# Identification of small molecule inhibitors of the DDI2 protease

> **NIH NIH R01** · VIRGINIA COMMONWEALTH UNIVERSITY · 2024 · $671,643

## Abstract

PROJECT SUMMARY
Proteasome inhibitors are currently being used in the clinic against Multiple myeloma. This
approach is thought to work at least in part because cancer cells appear to rely more heavily on
proteasomes than do normal cells. However, our previous studies showed that proteasome
inhibition invokes an adaptive program driven by the transcription factor NRF1 which
upregulates proteasome genes resulting in the recovery of proteasome activity, thus limiting the
efficacy of this approach. Consistent with this notion, our preliminary data suggest that
depletion of NRF1 potentiates the action of proteasome inhibition therapy in a breast cancer
xenograft model. Taking advantage of the fact that a protease DDI2 is essential for NRF1
activation, here we propose to identify small molecule inhibitors of this protease that could be
used to enhance the efficacy of proteasome inhibitors. Moreover, based on our preliminary data
that showed depleting DDI2 in itself retards tumor growth, DDI2 inhibitors could also find use as
a single-agent. Based on our pilot screen that demonstrates feasibility and consistent with the
goals of PAR-20-271, this 4-year project will pursue the following specific aims. In AIM 1, we
will express and purify DDI2 protein and perform high-throughput screens using a protein
thermal shift (PTS) assay to identify compounds that bind DDI2. In AIM 2, we will perform hit
selection, confirmation and profiling using a panel of secondary assays that includes orthogonal
and counter-screen assays as well as biophysical assays. In AIM 3, we will perform hit
validation, hit expansion, probe selection and profile the mechanism of action of hits, followed
by cellular assays to assess DDI2 target engagement, impact on the DDI2-NRF1 axis and
cancer cell apoptosis.

## Key facts

- **NIH application ID:** 10825596
- **Project number:** 5R01CA279255-02
- **Recipient organization:** VIRGINIA COMMONWEALTH UNIVERSITY
- **Principal Investigator:** Gary L. Kleiger
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $671,643
- **Award type:** 5
- **Project period:** 2023-04-10 → 2027-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10825596

## Citation

> US National Institutes of Health, RePORTER application 10825596, Identification of small molecule inhibitors of the DDI2 protease (5R01CA279255-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10825596. Licensed CC0.

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