Effects of TAK-029, a novel GPIIb/IIIa antagonist, on arterial thrombosis in guinea pigs, dogs and monkeys

Adhesion of adenosine diphosphate-activated platelets to human brain microvascular endothelial cells under flow in vitro is mediated via GPIIb/IIIa

Employing video-enhanced contrast (VEC) microscopy, we examined whether TAK-029 (GPIIb/IIIa antagonist) inhibits the adhesion of activated platelets to human brain microvascular endothelial cells (HBEC) in vitro. HBECs were cultured on a coverglass and put in the observation chamber of VEC microscopy. Then, activated platelets by adenosine diphosphate (ADP) (2 microM) were perfused over HBEC at a low shear rate of 10 s(-1) for 30 min and washed out. Platelets adhered directly to HBEC. However, platelet adhesion to HBEC was suppressed when platelet rich plasma with ADP (2 microM) plus TAK-029 (GPIIb/IIIa antagonist; 1 microM) was perfused over HBEC for 30 min and washed out. Anti-GPIbalpha antibody (GUR20-5) did not inhibit adhesion of ADP-activated platelets to HBEC. The above results showed adhesion of ADP-activated platelets to HBEC under flow in vitro is mediated via GPIIb/IIIa

Antiaggregatory, antithrombotic effects of MS-180, a novel platelet glycoprotein IIb/IIIa receptor antagonist

The antiaggregatory and antithrombotic effects of (S)-(-)-ethyl[6-[4-(morpholinoformimidoyl)benzamido]-3,4-dihydro-2 H-1-benzo-pyran-3-yl]acetate hydrochloride (MS-180), a novel platelet glycoprotein IIb/IIIa receptor antagonist, were investigated. Ma-HCl, (S)-(-)-[6-[4-(Morpholinoformimidoyl)benzamido]-3,4-dihydro-2H-1-b enzopyran-3-yl]acetic acid hydrochloride, the hydrochloride salt of Ma (active metabolite), inhibited the binding of fibrinogen to immobilized human glycoprotein IIb/III receptor with an IC50 value of 0.12+/-0.03 nM without affecting binding to either fibronectin or vitronectin receptors. In anesthetized guinea pigs, intraduodenal administration of MS-180 caused dose-dependent inhibition of both ADP- and collagen-induced ex vivo platelet aggregation. At the same dosages, occluded thrombus formation and platelet release reactions were also markedly suppressed. In anesthetized dogs, the bleeding time was prolonged slightly even when submaximal inhibition (< 90%) of ex vivo platelet aggregation was achieved following i.v. administration of Ma-HCl. Aspirin (100 mg/kg) prolonged the bleeding time to the same extent as MS-180 (1 mg/kg), although it suppressed only collagen-induced platelet aggregation. Therefore, MS-180 may be clinically useful for the treatment of thrombotic diseases.

Novel non-peptide fibrinogen receptor antagonists. 1. Synthesis and glycoprotein IIb-IIIa antagonistic activities of 1,3,4-trisubstituted 2-oxopiperazine derivatives incorporating side-chain functions of the RGDF peptide

Based on the lead tetrapeptide RGDF, two possible non-peptide glycoprotein (GP) IIb-IIIa antagonists possessing an (S)-2-oxopiperazine-3-acetic acid moiety as a scaffold incorporating the indispensable Asp fragment were prepared, and (S)-4-[[trans-[4-(guanidinomethyl)-cyclohexyl]carbonyl]glycyl]-2- oxopiperazine-1,3-diacetic acid, 1a, was identified as a potential lead. A series of 3-substituted 2-oxopiperazine-1-acetic acids bearing the Arg-Gly equivalent at the 4-position were prepared and evaluated for their ability to prevent platelet aggregation and for their binding affinity for the GP IIb-IIIa receptor purified from human HEL cells. (S)-4-[(4-Amidinobenzoyl)glycyl]-3-[(methoxycarbonyl)methyl]- 2-oxopiperazine-1-acetic acid, 9 (TAK-029), inhibited in vitro human platelet aggregation with an IC50 value of 0.03 microM and GP IIb-IIIa-fibrinogen binding with an IC50 value of 0.49 nM. The [4-(2-aminoethyl)benzoyl]glycyl derivative 26 showed activity comparable to that of 9 (IC50 = 0.093 microM, guinea pig platelet aggregation assay). Compound 9 dose-dependently inhibited ex vivo platelet aggregation in guinea pigs (0.03 and 0.1 mg/kg, i.v.), and long-lasting inhibition of platelet aggregation was observed upon oral administration of 9 (3 mg/kg) to guinea pigs. On the other hand, the activity of 26 disappeared within 1 h after a dose of 1 mg/kg (i.v.). Compound 9 may therefore be useful in the clinical treatment of arterial thrombotic diseases.