GFER Represents a Target for Dual Disruption of Redox Homeostasis and Reactivation of the Immune Response in Pancreatic Adenocarcinoma.

Both metabolic dysregulation and the immunosuppressive tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC) contribute to the recalcitrance of this lethal disease to treatment. Accordingly, we aimed to identify and characterize a target that elicits an anticancer response through both disrupting cancer cell redox homeostasis and increasing the immunogenicity of PDAC. First, mitochondrial metabolic dependencies in PDAC were identified by using a CRISPR-Cas9 screening system with a custom single-guide RNA library. Functional validation analyses revealed GFER, a mitochondrial FAD-dependent sulfhydryl oxidase, as an essential regulator of tumor growth. In vitro and in vivo methodologies demonstrated that GFER depletion perturbed redox homeostasis and stimulated tumor immunogenicity, including sensitization to immune checkpoint blockade. In patient-derived xenograft models of PDAC, the growth-inhibitory response induced by GFER depletion was mediated by an altered oxidative balance that released damaged mitochondrial DNA into the cytoplasm of tumor cells, leading to the activation of the cGAS-STING pathway and expression of type I IFNs. This effect was recapitulated in a mouse immunocompetent syngeneic PDAC model, in which GFER depletion suppressed tumor growth and promoted T-cell infiltration to enhance tumor-killing effects. Consequently, GFER depletion significantly increased the antitumor efficacy of immune checkpoint blockade. Overall, these findings identify GFER as a critical node for both mitochondrial redox homeostasis and immunomodulation in PDAC and reveal a therapeutic opportunity for sensitizing PDAC to immune checkpoint blockade. SIGNIFICANCE: GFER is essential for mitochondrial redox balance and suppressing tumor immunogenicity in pancreatic tumors, with the combination of GFER inhibition with immune checkpoint blockade resulting in a strong antitumor response.