Metabolites of PPI-2458, a selective, irreversible inhibitor of methionine aminopeptidase-2: structure determination and in vivo activity.
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.
GlaxoSmithKline, 830 Winter Street, Waltham, MA 02451-1420, USA. christopher.c.arico-muendel@gsk.com
Christopher C
CC
Arico-Muendel
Bruce
B
Belanger
Dennis
D
Benjamin
Heather S
HS
Blanchette
Teresa M
TM
Caiazzo
Paolo A
PA
Centrella
Jennifer
J
DeLorey
Elisabeth G
EG
Doyle
Ulrike
U
Gradhand
Sarah T
ST
Griffin
Susan
S
Hill
Matthew T
MT
Labenski
Barry A
BA
Morgan
Gary
G
O'Donovan
Kavirayani
K
Prasad
Steven
S
Skinner
Nazbeh
N
Taghizadeh
Charles D
CD
Thompson
James
J
Wakefield
William
W
Westlin
Kerry F
KF
White
D000626:Aminopeptidases / Q000037:antagonists & inhibitors* / Q000097:blood; D020533:Angiogenesis Inhibitors / Q000493:pharmacokinetics* / Q000494:pharmacology*; D000818:Animals; D004334:Drug Administration Schedule; D004852:Epoxy Compounds / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics* / Q000494:pharmacology; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism; D008198:Lymph Nodes / Q000187:drug effects / Q000378:metabolism; D008228:Lymphoma, Non-Hodgkin / Q000097:blood / Q000188:drug therapy; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors* / Q000097:blood; D008862:Microsomes, Liver / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D013329:Structure-Activity Relationship; D013950:Thymus Gland / Q000187:drug effects / Q000378:metabolism; D014633:Valine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis / Q000493:pharmacokinetics / Q000494:pharmacology
D020533:Angiogenesis Inhibitors; D004852:Epoxy Compounds; C488724:PPI 2458; D000626:Aminopeptidases; C106541:methionine aminopeptidase 2; D008666:Metalloendopeptidases; D014633:Valine