Co-targeting IGF-1R and Glutaminase in Ewing Sarcoma

Aberrant activation of receptor tyrosine kinases (RTK) drives or enables tumorigenesis, metastasis, and therapeutic resistance across cancers but RTK targeting is only successful in few of these. IGF-1R provides a key oncogenic axis in Ewing Sarcoma (EWS), the second most common malignant bone tumor of children and young adults with a 5-year survival rate of only 39% once metastasized. Yet, clinical trials showed limited responses to IGF-1R inhibitors in EWS. An essential cancer hallmark is the metabolic rewiring with enhanced accumulation of glucose and its aerobic glycolysis (the Warburg effect). This helps reallocate glucose-derived metabolites for macromolecular synthetic needs of proliferative tumor cells and away from use in bioenergetics. Increased glucose uptake (using FDG-PET scanning) is a mark of EWS patient tumors and correlates with worse outcomes. Yet, knockdown (KD) of the EWS driver oncogene EWS-FLI1 led to enhanced glucose uptake and glycolysis, suggesting other molecular pathways counter the EWS-FLI1 effect to inhibit glycolysis. We identified EHD1, a member of the EPS15-Homology Domain-containing (EHD) protein family, as a required element of the EWS tumorigenesis and metastasis. Mechanistically, EHD1 promoted the intracellular traffic of IGF-1R to elevate its cell surface expression and signaling. Our new data demonstrate that EHD1 overexpression upregulates glucose uptake, essential for glycolysis, in an IGF-1R dependent manner. Metabolomics analyses demonstrated that EHD1-KO, which genetically mimics IGF-1R inhibition, in EWS cell models led to a switch to glutamine- dependent maintenance of TCA cycle, in the process of glutamine anaplerosis. Glutaminase 1 (GLS) or GLS2 convert glutamine to glutamate for entry into metabolic pathways. GLS is universally pro-oncogenic while GLS2 is context dependent. We found that EWS cells only express GLS. GLS inhibition is untested in EWS but effective in other cancer models. GLS inhibitor CB-839 (Telaglenastat) was found safe in phase 1 trials and is in phase 2 trials in prostate cancer (NCT04824937). We found CB-839 to inhibit EWS cell proliferation and migration at nanomolar IC50s, and to be synergistic with Linsitinib, an IGF-1R inhibitor in advanced clinical trials. We hypothesize that a metabolic switch to glutamine dependence sustains EWS tumorigenesis and metastasis in the face of IGF-1R inhibition, and thus concurrent targeting of IGF-1R and GLS will provide an effective targeted therapy approach for EWS. We propose complementary genetic and pharmacologic studies using cell line and Patient-derived xenograft (PDX)-derived tumor organoid models of EWS to assess if GLS is a valid therapeutic target in EWS (Aim 1) and if its co-targeting with IGF-1R inhibitors will be additive or synergistic (Aim 2). Our studies evaluate a novel hypothesis, use state of the art and innovative approaches, and explore a co-targeting approach not previously tested. Success of our studies will nominate IGF-1R and GLS inhibitors as a novel and safe combinatorial targeted therapy for EWS. The novel principle of IGF-R plus GLS inhibition may be extendable to other cancers (including NSCLC, breast, and thyroid) with an overactive EHD1-RTK axis. Project Number: 1R21CA297629-01A1 | Fiscal Year: 2025 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: Hamid Band | Institution: UNIVERSITY OF NEBRASKA MEDICAL CENTER, OMAHA, NE | Award Amount: $391,186 | Activity Code: R21 | Study Section: Special Emphasis Panel[ZCA1 SRB-P (M2)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11211704