Abstract A105: Pharmacological inhibition of nicotinamide adenine dinucleotide (NAD+) production enzyme nicotinamide phosphoribosyltransferase (NAMPT) impairs cellular survival, energy metabolism, and tumor growth in neuroblastoma (NB) models
Authors: Varriano Sophia , Lee Unsun , Collins Victor , Nguyen Rosa , Issaq Sameer , Sun Ming , Nelson Ariana , Yeung Choh , Thomas Craig , Mendoza Arnulfo , Thiele Carol , Heske Christine 
Published: December 2023

Abstract
Background: Neuroblastoma is the most common extracranial solid tumor in children. High-risk patients have a poor prognosis with an overall survival rate of &lt;50%, thus novel therapeutic strategies are critically needed. To address this need, we performed a high-throughput drug screen and identified nicotinamide phosphoribosyltransferase inhibitors (NAMPTis) as highly active against neuroblastoma cells compared to other cancer cell types. NAMPT is the rate-limiting enzyme in the nicotinamide adenine dinucleotide (NAD+) salvage pathway, which cancer cells preferentially utilize to generate NAD+, a key co-factor that plays essential roles in energy metabolism. In this study, we investigated the translational potential and mechanistic effects of NAMPT inhibition in preclinical neuroblastoma models.
Methods/Results: Using 3 NAMPTis on a panel of 10 neuroblastoma cell lines, we confirmed that a majority of these models were highly responsive to NAMPTis by Incucyte Live-Cell proliferation analysis. Notably, we observed complete growth inhibition in most models at doses &lt;3.2nM of OT-82, a clinically relevant NAMPTi with a more favorable toxicity profile. On-target activity was confirmed by dose-dependent depletion of intracellular NAD+ in cells treated with OT-82. As NAD+ is necessary for energy metabolism, particularly ATP production, we performed a Cell-Titer Glo assay to indirectly assess ATP levels and observed decreases in all models with OT-82 treatment. Glycolysis and oxidative phosphorylation (OXPHOS) are two processes involved in ATP production that utilize NAD+, thus we measured activity of both processes via biochemical and extracellular flux analyses. With OT-82 treatment, we observed decreases in glucose consumption and lactate production in most models, and decreases in OXPHOS in some cell lines. Finally, an in vivo pilot study testing OT-82 in an orthotopic neuroblastoma PDX model demonstrated antitumor activity.
Conclusion: Together, these data show that neuroblastoma is susceptible to disruption of the NAMPT pathway and suggest that NAMPTis have translational potential as a novel therapy for neuroblastoma patients.
Citation Format: Sophia Varriano, Unsun Lee, Victor Collins, Rosa Nguyen, Sameer Issaq, Ming Sun, Ariana Nelson, Choh Yeung, Craig Thomas, Arnulfo Mendoza, Carol Thiele, Christine Heske. Pharmacological inhibition of nicotinamide adenine dinucleotide (NAD+) production enzyme nicotinamide phosphoribosyltransferase (NAMPT) impairs cellular survival, energy metabolism, and tumor growth in neuroblastoma (NB) models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A105.