Therapeutic NAMPT inhibition reveals a targetable metabolic vulnerability in neuroblastoma

Abstract

Neuroblastoma (NB) remains a major cause of pediatric cancer mortality for which new therapeutic strategies are needed. Exploitation of reprogrammed metabolic pathways offers an opportunity for cell-type specific anticancer therapeutics. To identify pediatric solid tumors with an enhanced susceptibility to targeting the nicotinamide adenine dinucleotide (NAD + ) salvage pathway, we performed an unbiased high-throughput screen of over 200 cancer cell line models using inhibitors of nicotinamide phosphoribosyltransferase (NAMPT), the rate limiting enzyme in the NAD + salvage pathway. Our analysis identified NB as one of the most sensitive solid tumor types, prompting further investigation of NAMPT inhibition as a potential therapeutic strategy in this disease. Using two early phase clinical NAMPT inhibitors (OT-82 and KPT-9274), we validated screen results using assays of proliferation and survival in a panel of molecularly diverse NB cell lines. Effects on proliferation, survival, NAD + abundance, adenosine triphosphate (ATP) levels, and energy-related metabolites were quantified, and downstream consequences of NAD + -consuming enzymatic pathways were examined. Tolerability, antitumor activity and pharmacodynamic effects of OT-82 were evaluated in three orthotopic NB mouse models. In the drug screen, NB models ranked among the most sensitive pediatric solid tumor cells lines to NAMPT inhibition. OT-82 and KPT-9274 potently suppressed proliferation and viability across multiple molecularly diverse NB models in an on-target manner. Mechanistically, NAMPT inhibition resulted in rapid depletion of NAD + and ATP, disruption of energy metabolism, accumulation of DNA damage, and induction of irreversible non-apoptotic cellular death. In vivo, OT-82 was well tolerated and produced marked antitumor activity, including tumor regressions in orthotopic NB models, including several with regional liver metastases. Pharmacodynamic analysis confirmed intratumoral NAD + depletion during treatment, demonstrating on-target pathway inhibition in vivo. These findings identify NB as a highly NAMPT inhibitor-sensitive pediatric solid tumor and establish NAMPT-dependent NAD + biosynthesis as a targetable metabolic vulnerability in this disease. By integrating an unbiased discovery screen with mechanistic and orthotopic in vivo validation using clinically relevant inhibitors, this study provides a strong translational rationale for clinical investigation of NAMPT inhibitors in NB.