Abstract 3524: Novel prodrugs of the glutamine antagonist 6-diazo-5-oxo-norleucine (DON) as treatment for malignant peripheral nerve sheath tumor

Neurofibromatosis Type I (NF1) is a heritable tumor predisposition syndrome in which up to 10% of patients develop malignant peripheral nerve sheath tumor (MPNST), an aggressive sarcoma. For MPNST that is incompletely resected at diagnosis, traditional cytotoxic chemotherapeutic strategies offer a 5 year event-free survival of less than 40%; thus new therapeutic strategies are desperately needed. Reprogramming of energy metabolism, whereby tumor cells take up more glutamine than healthy cells and direct this substrate to replenish metabolites for proliferation, is a hallmark of several cancers that has not been effectively leveraged for treatment of MPNST. Our group has recently described JHU 395, a nervous system targeted prodrug of the glutamine antagonist 6-diazo-5-oxo-norleucine (DON) which delivers DON preferentially to the brain resulting in less gastrointestinal toxicity, which was the main toxicity of DON in past clinical trials. The primary goals of this study were to evaluate glutamine antagonism and JHU 395 activity in MPNST. Using multiple Schwann and MPNST cell lines we investigated cell proliferation in culture under glutamine deprivation and antagonism. Mass spectrometry (MS)-based metabolomic profiling was used to characterize differences between MPNST cells treated with vehicle versus DON. MS-based bioanalytical methods were also used to investigate DON delivery to tumor cells by JHU 395. We found that growth of MPNST cells in culture is preferentially inhibited by glutamine deprivation and DON treatment when compared to immortalized Schwann cells derived from non-tumored nerve (IC50 of 8-9 micromolar versus >30 micromolar). Targeted metabolomics analyses of DON treated human MPNST cells demonstrated multiple differences in downstream glutamine-dependent metabolites including intermediates in purine synthesis and amino acid synthesis, suggesting that DON acts broadly within the tumor cell to inhibit growth. While DON showed limited partitioning into MPNST cells versus plasma, JHU 395 preferentially delivered DON into MPNST with over 5-fold higher cell-to-plasma ratio. Prodrug pharmacokinetic studies in mouse demonstrated that oral administration of the prodrug safely delivered DON at micromolar concentrations to peripheral nerve. In conclusion, compared to healthy Schwann cells, MPNST cells have unique vulnerability to antagonizing glutamine utilization. The nervous system directed prodrug JHU 395 enhances DON delivery to MPNST and represents a novel potential therapeutic approach for these aggressive tumors. Based on these results we have initiated efficacy studies of JHU 395 in the murine NPcis (NF1+/-;p53+/-) model of MPNST. Citation Format: Kathryn Lemberg, Ying Wu, Jesse Alt, Liang Zhao, Alexandra J. Gadiano, Chabely Rodriguez, Rana Rais, Pavel Majer, Jaishri Blakeley, Barbara Slusher. Novel prodrugs of the glutamine antagonist 6-diazo-5-oxo-norleucine (DON) as treatment for malignant peripheral nerve sheath tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3524.