Next-Generation NAMPT Inhibitors Identified by Sequential High-Throughput Phenotypic Chemical and Functional Genomic Screens

Phenotypic high-throughput chemical screens allow for discovery of small molecules that modulate complex phenotypes and provide lead compounds for novel therapies; however, identification of the mechanistically relevant targets remains a major experimental challenge. We report the application of sequential unbiased high-throughput chemical and ultracomplex small hairpin RNA (shRNA) screens to identify a distinctive class of inhibitors that target nicotinamide phosphoribosyl transferase (NAMPT), a rate-limiting enzyme in the biosynthesis of nicotinamide adenine dinucleotide, a crucial cofactor in many biochemical processes. The lead compound STF-118804 is a highly specific NAMPT inhibitor, improves survival in an orthotopic xenotransplant model of high-risk acute lymphoblastic leukemia, and targets leukemia stem cells. Tandem high-throughput screening using chemical and ultracomplex shRNA libraries, therefore, provides a rapid chemical genetics approach for seamless progression from small-molecule lead identification to target discovery and validation. [Display omitted] •Sequential phenotypic and functional genomic screens enable drug target discovery•Structurally distinctive class of NAMPT inhibitors display wide therapeutic index•NAMPT inhibition is highly efficacious in xenograft model of acute lymphoid leukemia For those using phenotypic screening for drug discovery, target identification and mechanism of action remain a challenge. Matheny et al. employ sequential unbiased phenotypic small molecule screens and ultracomplex shRNA library screens to identify a class of highly specific NAMPT inhibitors.