title: Structural basis for resistance to diverse classes of NAMPT inhibitors.
abstract: Inhibiting NAD biosynthesis by blocking the function of nicotinamide phosphoribosyl transferase (NAMPT) is an attractive therapeutic strategy for targeting tumor metabolism. However, the development of drug resistance commonly limits the efficacy of cancer therapeutics. This study identifies mutations in NAMPT that confer resistance to a novel NAMPT inhibitor, GNE-618, in cell culture and in vivo, thus demonstrating that the cytotoxicity of GNE-618 is on target. We determine the crystal structures of six NAMPT mutants in the apo form and in complex with various inhibitors and use cellular, biochemical and structural data to elucidate two resistance mechanisms. One is the surprising finding of allosteric modulation by mutation of residue Ser165, resulting in unwinding of an α-helix that binds the NAMPT substrate 5-phosphoribosyl-1-pyrophosphate (PRPP). The other mechanism is orthosteric blocking of inhibitor binding by mutations of Gly217. Furthermore, by evaluating a panel of diverse small molecule inhibitors, we unravel inhibitor structure activity relationships on the mutant enzymes. These results provide valuable insights into the design of next generation NAMPT inhibitors that offer improved therapeutic potential by evading certain mechanisms of resistance.
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Weiru
authors.initials: W
authors.lastname: Wang
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Kristi
authors.initials: K
authors.lastname: Elkins
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Angela
authors.initials: A
authors.lastname: Oh
authors.affiliation: Forma Therapeutics, Inc., Watertown, Massachusetts, United States of America.
authors.forename: Yen-Ching
authors.initials: YC
authors.lastname: Ho
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Wu
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Yang
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Mandy
authors.initials: M
authors.lastname: Kwong
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Mary
authors.initials: M
authors.lastname: Coons
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Bobby
authors.initials: B
authors.lastname: Brillantes
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Eric
authors.initials: E
authors.lastname: Cheng
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Lisa
authors.initials: L
authors.lastname: Crocker
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Dragovich
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Deepak
authors.initials: D
authors.lastname: Sampath
authors.affiliation: Forma Therapeutics, Inc., Watertown, Massachusetts, United States of America.
authors.forename: Xiaozhang
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Forma Therapeutics, Inc., Watertown, Massachusetts, United States of America.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Bair
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Thomas
authors.initials: T
authors.lastname: O'Brien
authors.affiliation: Genentech, Inc., South San Francisco, California, United States of America.
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Belmont
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D020134:Catalytic Domain; D045744:Cell Line, Tumor; D016207:Cytokines / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D054409:Nicotinamide Phosphoribosyltransferase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D016207:Cytokines; D004791:Enzyme Inhibitors; D054409:Nicotinamide Phosphoribosyltransferase; C085455:nicotinamide phosphoribosyltransferase, human