Abstract
Background:
Metabolic reprogramming, particularly upregulated de novo pyrimidine biosynthesis, drives cancer progression and immune evasion. Dihydroorotate dehydrogenase (DHODH), a key enzyme in this pathway, is a promising therapeutic target, but its inhibitors often face resistance in immune-refractory melanoma, linked to low basal stimulator of interferon genes (STING) expression.
Methods:
To overcome this limitation, we designed H62, a tumor-selective prodrug conjugating the DHODH inhibitor EA6 with the STING agonist MSA-2 via a cathepsin B-cleavable linker. Mechanistic studies evaluated mitochondrial disruption, pyroptosis (caspase-3/GSDME), and STING-mediated interferon signaling, alongside natural killer (NK) cell recruitment. Efficacy was tested in multiple melanoma models, including standard and neoadjuvant settings.
Results:
H62 synergistically induced mitochondrial dysfunction and pyroptosis while activating STING/type I interferon responses, enhancing NK cell cytotoxicity. In melanoma models, it significantly suppressed tumor growth, reduced postoperative recurrence, and improved survival.
Conclusions:
This dual-targeting strategy overcomes DHODH inhibitor resistance by coupling metabolic interference with innate immune activation, offering translational potential for melanoma and other treatment-resistant cancers.