Abstract 3602: JHU395, a nervous tissue penetrant glutamine antagonist, restricts growth of malignant peripheral nerve sheath tumor with inhibition of nucleotide synthesis
Authors: Lemberg Kathryn M. , Zhao Liang , Wu Ying , Alt Jesse , Aguilar Joanna Marie H. , Lam Jenny , Gadiano Alexandra J. , Rais Rana , Majer Pavel , Blakeley Jaishri , Slusher Barbara S. 
Published: August 2019

Abstract
Malignant peripheral nerve sheath tumor (MPNST) is a sarcoma that occurs in ~10% of patients with neurofibromatosis type I (NF1). Incomplete surgical resection at diagnosis leads to a 4-year event-free survival rate of &lt;30%. Thus, improved treatments are needed. Recent evidence suggests that perturbing glutamine utilization warrants further exploration as a potential therapeutic strategy for MPNST. Competitive glutamine antagonists (GA) have been studied in several clinical trials for sarcoma previously, but clinical development was hampered by gastrointestinal (GI) toxicity. JHU395 is a broadly active nervous tissue penetrant GA. JHU395 delivers active GA preferentially to nervous tissue which may result in less GI toxicity than was observed in past trials. The primary goals of this study were to evaluate JHU395 in preclinical models of MPNST and to investigate tumor metabolic changes in response to JHU395. We investigated glutamine antagonism on growth of MPNST cells in culture and murine flank MPNST. JHU395 was administered orally for 14 days to mice bearing inoculated tumors derived from the NPcis (NF1+/-;p53+/-) genetically engineered model of MPNST. Tumors were measured every other day and tumor volume was calculated as the primary endpoint. Concurrent evaluations of GI and neurotoxicity were performed as secondary endpoints. GA levels in tumor versus plasma were compared using a previously validated bioanalytical method. In vivo stable isotope labeled glutamine (15N2- or 13C5-labeled) flux analysis and targeted liquid chromatography-mass spectrometry (LC-MS) metabolomics were performed on murine tumors. Compared to immortalized Schwann cells, growth of MPNST was preferentially inhibited by GA (IC50=8 micromolar versus &gt;30 micromolar). JHU395 delivered GA to MPNST cells with &gt;4-fold higher cell-to-plasma ratio compared to native GA and maintained ~2.5-fold higher tumor-to-plasma GA levels in vivo. Mice treated with JHU395 had &gt;40% smaller mean tumor volume compared to controls with no overt toxicity. Quantitiative bioanalysis revealed that JHU395 treated tumors had &gt;60% higher glutamine levels compared to controls 30 minutes after oral dosing. In vivo flux analysis demonstrated that JHU395 preferentially affects tumor glutamine utilization for nucleotide synthesis, while glutamine-derived substrates for the citric acid cycle appear unaffected. In summary, JHU395 inhibits growth of MPNST with inhibition of glutamine utilization in nucleotide synthesis and is well-tolerated. Nervous tissue penetrant glutamine antagonism is a feasible and effective therapeutic approach in preclinical models of MPNST. Future studies will investigate JHU395 in combination with nucleotide synthesis inhibitors in MPNST and investigate JHU395 efficacy in additional sarcoma models including patient-derived samples.
Citation Format: Kathryn M. Lemberg, Liang Zhao, Ying Wu, Jesse Alt, Joanna Marie H. Aguilar, Jenny Lam, Alexandra J. Gadiano, Rana Rais, Pavel Majer, Jaishri Blakeley, Barbara S. Slusher. JHU395, a nervous tissue penetrant glutamine antagonist, restricts growth of malignant peripheral nerve sheath tumor with inhibition of nucleotide synthesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3602.