The 1p/19q co-deletion induces targetable and imageable vulnerabilities in glucose metabolism in oligodendrogliomas.

Background: The 1p/19q co-deletion is a hallmark of oligodendrogliomas. The goal of this study was to exploit metabolic vulnerabilities induced by the 1p/19q co-deletion for oligodendroglioma therapy and non-invasive imaging.

Methods: We used stable isotope tracing, mass spectrometry, and genetic and pharmacological approaches to interrogate [U- C]-glucose metabolism in patient-derived oligodendroglioma models (SF10417, BT88, BT54, TS603, NCH612). We examined whether tracing [6,6'- H]-glucose metabolism using deuterium metabolic imaging (DMI) provided an early readout of treatment response.

Results: The expression of the glycolytic enzyme enolase 1 (ENO1; chromosome 1p36.23) was reduced in patient-derived oligodendroglioma cells and patient biopsies due to the 1p/19q co-deletion and histone hypermethylation. Conversely, ENO2 was upregulated, an effect that was driven by mitogen-activated protein kinase (MAPK) signaling and ERK1-mediated phosphorylation and inactivation of the transcriptional repressor in oligodendrogliomas. Genetic ablation of ENO2 or pharmacological inhibition using POMHEX inhibited proliferation with nanomolar potency but was not cytotoxic to oligodendroglioma cells or tumor xenografts. Mechanistically, ENO2 loss abrogated [U- C]-glucose metabolism to lactate but shunted glucose towards biosynthesis of serine and purine nucleotides, an effect that was driven by phosphoglycerate dehydrogenase (PHGDH). Importantly, the PHGDH inhibitor D8 was synthetically lethal in combination with POMHEX, and the combination induced tumor regression Furthermore, DMI of lactate production from [6,6'- H]-glucose provided an early readout of response to combination therapy that preceded MRI-detectable alterations and reflected extended survival.

Conclusions: We have identified ENO2 and PHGDH as 1p/19q co-deletion-induced metabolic vulnerabilities in oligodendrogliomas and demonstrated that DMI reports on early response to therapy.

Key Points: The 1p/19q co-deletion upregulates ENO2 in oligodendrogliomas.ENO2 inhibition inhibits glycolysis but upregulates serine and nucleotide biosynthesis via PHGDH.Combined inhibition of ENO2 and PHGDH is lethal, an effect that can be visualized by DMI.

Importance Of The Study: Oligodendrogliomas are devastating primary brain tumors with long-lasting and life-altering effects on physical and cognitive function. The presence of a 1p/19q co-deletion defines oligodendrogliomas. Here, using clinically relevant patient-derived models and patient tissue, we show that the 1p/19q co-deletion leads to loss of the glycolytic enzyme ENO1 and upregulation of ENO2 in oligodendrogliomas. This provides a unique therapeutic opportunity since most cells rely on ENO1 for glycolysis. Targeting ENO2 using the brain-penetrant inhibitor POMHEX abrogates glycolysis but redirects glucose toward serine and nucleotide biosynthesis, an effect that is driven by PHGDH, the rate-limiting enzyme for serine biosynthesis. Importantly, combined treatment with POMHEX and the PHGDH inhibitor D8 is synthetically lethal and Furthermore, visualizing glucose metabolism using DMI provides an early readout of response to therapy that predicts extended survival . In summary, we have developed a unique integrated metabolic therapy and imaging approach for oligodendrogliomas.