# Metabolic flux analysis and PDX models to understand therapeutic vulnerabilities following inhibition of Ref-1 redox signaling in pancreatic cancer

> **NIH NIH R01** · INDIANA UNIVERSITY INDIANAPOLIS · 2024 · $443,001

## Abstract

ABSTRACT
Pancreatic ductal adenocarcinoma (PDAC) is particularly resistant to therapy and typically presents as
metastatic disease. Characterized by hypoxia, dense stroma, and metabolic rewiring, original approaches and
combination strategies are desperately needed. We propose to investigate inhibition of a redox signaling protein
and drug combinations that selectively kill the tumor by impinging on critical pathways the tumor is using to
survive. Redox factor-1 (Ref-1) regulates the activity of various transcription factors that drive pancreatic cancer
cell proliferation and drug resistance as well as genes involved in cellular metabolism. Under hypoxia, inhibition
of Ref-1 significantly perturbed metabolic pathways (TCA cycle and OXPHOS) and HIF-regulated genes, and
thus slowed the growth of pancreatic cancer co-culture spheroids and xenografts. The first-generation Ref-1
inhibitor (APX3330) completed phase I trial and demonstrated 32% response, predicted PK, and target
engagement with no significant toxicities. There was disease stabilization in six patients with four on treatment
for an extended time (>250 days). Based on encouraging phase I data and a detailed structural-activity
relationship (SAR) program, we have also identified next generation Ref-1 inhibitors that are at lead optimization
stage, a strategy to screen for patients that have sensitivity to Ref-1 inhibition, and molecular targets that are
likely to synergize with Ref-1 inhibition. However, adaptive mechanisms of resistance eventually emerge with
targeted therapy, therefore we will also focus on the development of novel combinations. Our hypothesis is that
targeting the redox function of Ref-1 alone and in mechanistically designed combination therapies will induce
metabolic lethality and inhibit pancreatic cancer growth and metastasis. In Aim 1, identification of metabolic
characteristics of cancer cells/tissues that associate with the outcome of Ref-1 inhibition and prediction of new
metabolic targets to improve the efficacy of Ref-1 inhibition. Our recently developed computational predictor of
cell-wise metabolic flux will be used to study the metabolic changes due to Ref-1 inhibition in PDAC cells at the
single cell level. In Aim 2, NMR to establish direct interactions of Ref-1 and the new analogues, efficacy, toxicity,
and metabolic stability studies will allow us to advance the top lead candidate(s) for in vivo studies for Candidate
Selection (NIH Milestone 4) and IND (Investigational New Drug) submission leading to eventual Phase I trial.
Lastly in Aim 3, evaluation of Ref-1 in preclinical combination therapy will be used to overcome adaptive
resistance. To further predict metabolic nodes that could be perturbed to synergize with Ref-1 inhibition, creating
a metabolic lethality, computational predictor of cell-wise metabolic flux described in Aim1 will be used. The
efficacy of Ref-1 alone and in new combinations will be investigated using organoids in vitro and the mous...

## Key facts

- **NIH application ID:** 10895579
- **Project number:** 5R01CA282478-02
- **Recipient organization:** INDIANA UNIVERSITY INDIANAPOLIS
- **Principal Investigator:** Melissa L. Fishel
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $443,001
- **Award type:** 5
- **Project period:** 2023-08-01 → 2028-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10895579

## Citation

> US National Institutes of Health, RePORTER application 10895579, Metabolic flux analysis and PDX models to understand therapeutic vulnerabilities following inhibition of Ref-1 redox signaling in pancreatic cancer (5R01CA282478-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10895579. Licensed CC0.

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