NNMT-driven metabolic reprogramming creates a NAMPT druggable vulnerability and reveals liquid biopsy biomarkers for TKI resistance in EGFR-mutant NSCLC

Abstract

Lung cancer is the deadliest neoplasia worldwide. Despite the availability of targeted therapies like tyrosine kinase inhibitors (TKIs) for EGFR-driven tumours in Non-Small Cell Lung Cancer (NSCLC), drug resistance remains a major factor that dramatically cuts life expectancy. Here we identify how increased expression of nicotinamide N-methyltransferase (NNMT) in TKI-resistant cancer cells diverts nicotinamide to synthesise 1-Methylnicotinamide (1-MNA) and lowers NAD⁺ levels that generates a druggable nicotinamide phosphoribosyltransferase (NAMPT) metabolic vulnerability. We also report that high blood levels of 1-MNA, the by-product of NNMT activity, are significantly associated with lower survival rates in EGFR TKI-treated NSCLC patients. Taken together, our findings describe a new and highly specific non-genetic metabolic synthetic lethality for mesenchymal-like tumours, which exposes NAMPT as an in vivo druggable target and establishes 1-MNA as a novel liquid biopsy biomarker to predict and monitor EGFR TKI resistance in NSCLC.

Keywords: EGFR; Liquid biopsy; Metabolic rewiring; NAMPT; NNMT; NSCLC; TKIs.