A-770041, a novel and selective small-molecule inhibitor of Lck, prevents heart allograft rejection.
Lck, one of eight members of the Src family of tyrosine kinases, is activated after T cell stimulation and is required for T-cell proliferation and interleukin (IL)-2 production. Inhibition of Lck has been a target to prevent lymphocyte activation and acute rejection. Here, we report the pharmacologic characterization of 1-methyl-1H-indole-2-carboxylic acid (4-{1-[4-(4-acetyl-piperazin-l-yl)-cyclohexyl]-4-amino-1H-pyrazolo[3,4-d]pyrimidin-3-yl}-2-methoxy-phenyl)-amide (A-770041), an orally bioavailable pyrazolo[3,4-d]pyrimidine with increased selectivity for Lck compared with previously reported compounds. A-770041 is a 147 nM inhibitor of Lck (1 mM ATP) and is 300-fold selective against Fyn, the other Src family kinase involved in T-cell signaling. Concanavalin A-stimulated IL-2 production in whole blood is inhibited by A-770041 with an EC50 of approximately 80 nM. A-770041 is orally bioavailable (F = 34.1 +/- 7.2% at 10 mg/kg) and has a t(1/2) of 4.1 +/- 0.1 h. Concanavalin A-induced IL-2 production in vivo is inhibited by oral administration of A-770041 (in vivo EC50 = 78 +/- 28 nM). Doses of A-770041 at or above 10 mg/kg/day prevent rejection of hearts transplanted heterotopically in rats from Brown Norway donors to Lewis recipients across a major histocompatibility barrier for least 65 days. Grafts from animals treated with 20 mg/kg/day A-770041 or 10 mg/day Cyclosporin A had minimal microvascular changes or multifocal mononuclear infiltrates. However, mineralization in myocytes from the grafts from A-770041-treated animals was less than animals treated with Cyclosporin A. Lck inhibition is an attractive target to prevent acute rejection.
Stachlewitz
Robert F
RF
Abbott Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA. robert.stachlewitz@abbott.com
Hart
Michelle A
MA
Bettencourt
Brian
B
Kebede
Tegest
T
Schwartz
Annette
A
Ratnofsky
Sheldon E
SE
Calderwood
David J
DJ
Waegell
Wendy O
WO
Hirst
Gavin C
GC
D000818:Animals; D006084:Graft Rejection / Q000517:prevention & control*; D016027:Heart Transplantation / Q000009:adverse effects*; D007376:Interleukin-2 / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000493:pharmacokinetics / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000037:antagonists & inhibitors*; D008297:Male; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew; D013601:T-Lymphocytes / Q000276:immunology; D014184:Transplantation, Homologous
C505452:1-methyl-1H-indole-2-carboxylic acid (4-(1-(4-(4-acetylpiperazin-1-yl)cyclohexyl)-4-amino-1H-pyrazolo(3,4-d)pyrimidin-3-yl)-2-methoxyphenyl)amide; D007376:Interleukin-2; D047908:Intracellular Signaling Peptides and Proteins; D011720:Pyrazoles; D011743:Pyrimidines; C015482:protein kinase modulator; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)