Metabolic imaging produces powerful visual assessments of organ function in vivo. Current techniques can be improved by safely increasing metabolic contrast. The gold standard, 2-[ ¹⁸ F]fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging, is limited by radioactive exposure and sparse assessment of metabolism beyond glucose uptake and retention. Deuterium magnetic resonance imaging (DMRI) with [6,6- ² H ₂ ]glucose is nonradioactive, achieves tumor metabolic contrast, but can be improved by enriched contrast from deuterated water (HDO) based imaging. Here, we developed a DMRI protocol employing [ ² H ₇ ]glucose. Imaging ² H-signal and measuring HDO production in tumor-bearing mice detected differential glucose utilization across baseline tumors, tumors treated with vehicle control or anti-glycolytic BRAFi and MEKi therapy, and contralateral healthy tissue. Control tumors generated the most ² H-signal and HDO. To our knowledge this is the first application of DMRI with [ ² H ₇ ]glucose for tumoral treatment monitoring. This approach demonstrates HDO as a marker of tumor glucose utilization and suggests translational capability in humans due to its safety, noninvasiveness, and suitability for serial monitoring.

The natural amino acid asparagine (Asn) is required by cells to sustain function and proliferation. Healthy cells can synthesize Asn through asparagine synthetase (ASNS) activity, whereas specific cancer and genetically diseased cells are forced to obtain asparagine from the extracellular environment. ASNS catalyzes the ATP-dependent synthesis of Asn from aspartate by consuming glutamine as a nitrogen source. Asparagine Synthetase Deficiency (ASNSD) is a disease that results from biallelic mutations in the ASNS gene and presents with congenital microcephaly, intractable seizures, and progressive brain atrophy. ASNSD often leads to premature death. Although clinical and cellular studies have reported that Asn deprivation contributes to the disease symptoms, the global metabolic effects of Asn deprivation on ASNSD-derived cells have not been studied. We analyzed two previously characterized cell culture models, lymphoblastoids and fibroblasts, each carrying unique ASNS mutations from families with ASNSD. Metabolomics analysis demonstrated that Asn deprivation in ASNS-deficient cells led to disruptions across a wide range of metabolites. Moreover, we observed significant decrements in TCA cycle intermediates and anaplerotic substrates in ASNS-deficient cells challenged with Asn deprivation. We have identified pantothenate, phenylalanine, and aspartate as possible biomarkers of Asn deprivation in normal and ASNSD-derived cells. This work implies the possibility of a novel ASNSD diagnostic via targeted biomarker analysis of a blood draw.