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

ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) exhibits an extraordinary resistance to therapy and often manifests as metastatic disease. It is characterized by hypoxia, a dense stroma, and metabolic alterations, necessitating innovative strategies for intervention. Our proposed investigation centers on two main fronts: targeting a redox

signaling protein and developing drug combinations that hold the potential to selectively eliminate the tumor by disrupting essential survival pathways. This redox factor-1 (Ref-1) is a regulator of critical transcription factors that fuel pancreatic cancer cell proliferation and resistance to drugs, as well as genes integral to cellular

metabolism. In hypoxic environments, the inhibition of Ref-1 markedly disrupts metabolic pathways (such as the TCA cycle and oxidative phosphorylation), along with genes influenced by hypoxia-inducible factors (HIFs). This interference effectively retards the growth of pancreatic cancer co-culture spheroids and xenografts. An initial

Ref-1 inhibitor (APX3330) has completed phase I trials, showcasing promising attributes: a 32% response rate, favorable pharmacokinetics, substantial target engagement, and minimal toxicity. Encouraged by these results and guided by a robust structural-activity relationship (SAR) exploration, we have identified next-generation Ref-

1 inhibitors currently in the lead optimization phase. Additionally, we have devised a strategy for patient selection based on Ref-1 sensitivity and identified molecular partners likely to synergize with Ref-1 inhibition. Acknowledging the eventual emergence of resistance mechanisms with targeted therapies, our research

endeavors also encompass the formulation of innovative combination strategies. Our overarching hypothesis posits that by focusing on the redox function of Ref-1, both as a standalone therapy and in conjunction with meticulously designed combination approaches, we can induce metabolic vulnerability and effectively curtail

pancreatic cancer growth and metastasis.