Background: NAMPT catalyzes the rate-limiting reaction in converting nicotinamide to NAD ϩ in cancers.

The route selection and process research and development of a practical synthesis for JAK2 inhibitor LY2784544 is described. The first-generation synthesis route, similar to that used in discovery for derivatization of a benzylic amine moiety, was 14 overall steps and possessed several steps that required extensive development for large-scale production. Route selection considerations led to a modified synthesis that utilized a novel vanadium-catalyzed carbon–carbon bond-forming arylation reaction for incorporation of the key benzylic morpholine moiety. A protecting group used to mask an amino pyrazole unit was modified from PMB to tert-butyl, resulting in a dramatic reduction in the overall length of the route. These two major changes resulted in an eight-step synthesis, which was six steps shorter than the first-generation synthesis. In the pilot plant, the new synthesis was scaled to produce >100 kg of LY2784544 in high yield and purity under GMP conditions. The overall development including the vanadium-catalyzed C–C bond-forming methodology, a ketone reductive deoxygenation, and a palladium-catalyzed amination is described.

Owing to the prevalence of the JAK2V617F mutation in myeloproliferative neoplasms (MPNs), its constitutive activity, and ability to recapitulate the MPN phenotype in mouse models, JAK2V617F kinase is an attractive therapeutic target. We report the discovery and initial characterization of the orally bioavailable imidazopyridazine, LY2784544, a potent, selective and ATP-competitive inhibitor of janus kinase 2 (JAK2) tyrosine kinase. LY2784544 was discovered and characterized using a JAK2-inhibition screening assay in tandem with biochemical and cell-based assays. LY2784544 in vitro selectivity for JAK2 was found to be equal or superior to known JAK2 inhibitors. Further studies showed that LY2784544 effectively inhibited JAK2V617F-driven signaling and cell proliferation in Ba/F3 cells (IC50=20 and 55 nM, respectively). In comparison, LY2784544 was much less potent at inhibiting interleukin-3-stimulated wild-type JAK2-mediated signaling and cell proliferation (IC50=1183 and 1309 nM, respectively). In vivo, LY2784544 effectively inhibited STAT5 phosphorylation in Ba/F3-JAK2V617F-GFP (green fluorescent protein) ascitic tumor cells (TED50=12.7 mg/kg) and significantly reduced (P<0.05) Ba/F3-JAK2V617F-GFP tumor burden in the JAK2V617F-induced MPN model (TED50=13.7 mg/kg, twice daily). In contrast, LY2784544 showed no effect on erythroid progenitors, reticulocytes or platelets. These data suggest that LY2784544 has potential for development as a targeted agent against JAK2V617F and may have properties that allow suppression of JAK2V617F-induced MPN pathogenesis while minimizing effects on hematopoietic progenitor cells.

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NAMPT, an enzyme essential for NAD þ biosynthesis, has been extensively studied as an anticancer target for developing potential novel therapeutics. Several NAMPT inhibitors have been discovered, some of which have been subjected to clinical investigations. Yet, the on-target hematological and retinal toxicities have hampered their clinical development. In this study, we report the discovery of a unique NAMPT inhibitor, LSN3154567. This molecule is highly selective and has a potent and broad spectrum of anticancer activity. Its inhibitory activity can be rescued with nicotinic acid (NA) against the cell lines proficient, but not those deficient in NAPRT1, essential for converting NA to NAD þ