PT  - JOURNAL ARTICLE
AU  - Christopher C. Arico-Muendel
AU  - Bruce Belanger
AU  - Dennis Benjamin
AU  - Heather S. Blanchette
AU  - Teresa M. Caiazzo
AU  - Paolo A. Centrella
AU  - Jennifer DeLorey
AU  - Elisabeth G. Doyle
AU  - Ulrike Gradhand
AU  - Sarah T. Griffin
AU  - Susan Hill
AU  - Matthew T. Labenski
AU  - Barry A. Morgan
AU  - Gary O’Donovan
AU  - Kavirayani Prasad
AU  - Steven Skinner
AU  - Nazbeh Taghizadeh
AU  - Charles D. Thompson
AU  - James Wakefield
AU  - William Westlin
AU  - Kerry F. White
TI  - Metabolites of PPI-2458, a Selective, Irreversible Inhibitor of Methionine Aminopeptidase-2: Structure Determination and In Vivo Activity
AID  - 10.1124/dmd.112.048355
DP  - 2013 Apr 01
TA  - Drug Metabolism and Disposition
PG  - 814--826
VI  - 41
IP  - 4
4099  - http://dmd.aspetjournals.org/content/41/4/814.short
4100  - http://dmd.aspetjournals.org/content/41/4/814.full
SO  - Drug Metab Dispos2013 Apr 01; 41
AB  - The natural product fumagillin exhibits potent antiproliferative and antiangiogenic properties. The semisynthetic analog PPI-2458, [(3R,4S,5S,6R)-5-methoxy-4-[(2R,3R)-2-methyl-3-(3-methylbut-2-enyl)oxiran-2-yl]-1-oxaspiro[2.5]octan-6-yl] N-[(2R)-1-amino-3-methyl-1-oxobutan-2-yl]carbamate, demonstrates rapid inactivation of its molecular target, methionine aminopeptidase-2 (MetAP2), and good efficacy in several rodent models of cancer and inflammation with oral dosing despite low apparent oral bioavailability. To probe the basis of its in vivo efficacy, the metabolism of PPI-2458 was studied in detail. Reaction phenotyping identified CYP3A4/5 as the major source of metabolism in humans. Six metabolites were isolated from liver microsomes and characterized by mass spectrometry and nuclear resonance spectroscopy, and their structures were confirmed by chemical synthesis. The synthetic metabolites showed correlated inhibition of MetAP2 enzymatic activity and vascular endothelial cell growth. In an ex vivo experiment, MetAP2 inhibition in white blood cells, thymus, and lymph nodes in rats after single dosing with PPI-2458 and the isolated metabolites was found to correlate with the in vitro activity of the individual species. In a phase 1 clinical study, PPI-2458 was administered to patients with non-Hodgkin lymphoma. At 15 mg administered orally every other day, MetAP2 in whole blood was 80% inactivated for up to 48 hours, although the exposure of the parent compound was only ∼10% that of the summed cytochrome P450 metabolites. Taken together, the data confirm the participation of active metabolites in the in vivo efficacy of PPI-2458. The structures define a metabolic pathway for PPI-2458 that is distinct from that of TNP-470 ([(3R,4S,5S,6R)-5-methoxy-4-[(2R,3R)-2-methyl-3-(3-methylbut-2-enyl)oxiran-2-yl]-1-oxaspiro[2.5]octan-6-yl] N-(2-chloroacetyl)carbamate). The high level of MetAP2 inhibition achieved in vivo supports the value of fumagillin-derived therapeutics for angiogenic diseases.