GMX1777 is a prodrug of the small molecule GMX1778, currently in phase I clinical trials for the treatment of cancer. We describe findings indicating that GMX1778 is a potent and specific inhibitor of the NAD ؉ biosynthesis enzyme nicotinamide phosphoribosyltransferase (NAMPT). Cancer cells have a very high rate of NAD ؉ turnover, which makes NAD ؉ modulation an attractive target for anticancer therapy. Selective inhibition by GMX1778 of NAMPT blocks the production of NAD ؉ and results in tumor cell death. Furthermore, GMX1778 is phosphoribosylated by NAMPT, which increases its cellular retention. The cytotoxicity of GMX1778 can be bypassed with exogenous nicotinic acid (NA), which permits NAD ؉ repletion via NA phosphoribosyltransferase 1 (NAPRT1). The cytotoxicity of GMX1778 in cells with NAPRT1 deficiency, however, cannot be rescued by NA. Analyses of NAPRT1 mRNA and protein levels in cell lines and primary tumor tissue indicate that high frequencies of glioblastomas, neuroblastomas, and sarcomas are deficient in NAPRT1 and not susceptible to rescue with NA. As a result, the therapeutic index of GMX1777 can be widended in the treatment animals bearing NAPRT1-deficient tumors by coadministration with NA. This provides the rationale for a novel therapeutic approach for the use of GMX1777 in the treatment of human cancers.

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Recently we created the novel indolylprodigiosin derivative 2 (obatoclax) and demonstrated its ability to antagonize multiple members of the B-cell lymphoma (Bcl) family of antiapoptotic proteins. The compound has shown potent anticancer activity in several animal tumor models. Obatoclax is now in Phase 1b and 2 clinical trials directed against multiple hematologic and solid tumor malignancies. To support its clinical development, a new scalable synthesis was required. Obatoclax has been prepared using a three-step synthesis, starting from commercially available 4-methoxy-3-pyrrolin-2-one. The reaction sequence involves a haloformylation reaction followed by a Suzuki cross-coupling reaction with an indole-2-boronic acid. The synthesis is completed by an acid-mediated condensation with 2,4-dimethyl-1H-pyrrole.