Selective targeting of NRF2-high pancreatic ductal adenocarcinoma with an NQO1-activatable prodrug

Activation of transcription factor NRF2 in pancreatic ductal adenocarcinoma (PDAC) promotes aggressive tumor phenotype and protection from therapy-induced oxidative stress. We postulated that NRF2^high PDAC can be selectively targeted by C29h, a prodrug that is activated by the NRF2-induced enzyme NAD(P)H:quinone oxidoreductase-1 (NQO1), which is elevated in human pancreatic tumors. Initial evaluations of C29h alone or together with the standard-of-care chemotherapeutic drug gemcitabine were conducted on NQO1^high human and mouse PDAC cell lines and patient-derived organoids. As PDAC is enriched in collagen-containing extracellular matrix (ECM) that activates NRF2 and induces NQO1 expression, we examined the ECM effect on the response to C29h, as well as in vivo tumor control in IKKα-deficient <i>Kras^G12D/Ikkα^ΔPEC</i> mice in which NRF2 is strongly activated, immunocompromised <i>Nu/Nu</i> mice orthotopically transplanted with human PDAC cells and C57BL/6n and NOD/SCID mice transplanted with mouse PDAC. C29h led to NQO1-dependent killing of human and mouse PDAC cell lines and organoids and acted additively with gemcitabine. Furthermore, ECM-plated PDAC cells were more susceptible to C29h cytotoxicity than cells grown on plastic. Importantly, C29h treatment induced tumor regression and increased the survival of PDAC-bearing mice and optimal C29h-induced tumor regression was dependent on CD8⁺ T lymphocytes whose tumoral recruitment was enhanced by drug treatment. This study supports the use of C29h alone or as part of a drug combination as an effective and promising strategy for selective eradication of NRF2^high PDAC.