Introduction: Intravesical interferon-alpha (IFNa) gene therapy with Nadofaragene firadenovec recently demonstrated clinical efficacy in patients with non-muscle invasive bladder cancer (NMIBC) in a phase 3 clinical trial. Optimizing the clinical efficacy of IFNa gene therapy requires an understanding of oncogenic pathways involved in tumor resistance. Our objective was to investigate the impact of IFNa gene therapy on tumor cell glucose and lipid metabolism to elucidate mechanisms of tumor resistance.
Methods: Murine bladder cancer cell lines treated with recombinant IFNa (rIFNa) and lentiviral IFN (LV-IFNa) and analyzed by whole-transcriptome sequencing, glucose uptake, and lactate production in vitro. In a murine bladder cancer model, mice were treated with LV-IFNa (orthotopic tumor model) or PolyI:C (flank tumor model), a potent IFN inducer. Disease response was monitored by real-time luciferase imaging in vivo and tumors were harvested for whole-transcriptome sequencing to assess effects of IFNa therapy on tumor metabolism and lipidomics. In parallel, lipidomic profiling was also performed on patient urine samples and tumor tissue from a phase 2 clinical trial of intravesical Nadofaragene firadenovec to assess for clinically relevant differences in lipid metabolism. Quantitative PCR (Q-PCR) was used to validate expression levels of differentially expressed candidate genes.
Results: We identified several genes involved in fatty acid synthesis to be downregulated and genes involved in glycolysis to be upregulated following treatment with IFNa in both cell lines and in mouse models. Q-PCR analysis was used to confirm changes in these genes. We performed lipidomics on mouse tumors treated with poly (I:C) and identified 79 lipids that were upregulated and 12 lipids were downregulated. Among IFNa responders, three major classes of lipids were upregulated - phosphotidyl choline, spingomyelin and phosphotidyl ethanolamine and one major class of lipid cardiolipin was downregulated. We also measured lactate levels and glucose uptake and found increased glucose uptake and lactate levels suggesting increased glycolysis in IFNa resistant cells. Lipidomics performed on patient urine samples collected pre- and post-treatment with intravesical Nadofaragene firadenovec detected >592 lipids with distinct expression profiles differentiating clinical responders and non-responders at both timepoints.
Conclusions: We demonstrate a novel mechanism by which IFNa modulates tumor cell metabolism and contributes to resistance development.
Source of Funding: CA201117 DoD TTSA award to Dr. Dinney and Dr. McConkey
University of Eastern Finland awarded to Dr. Dinney
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