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Suzuki KI, Sato K, Kamohara M, Kaku S, Kawasaki T, Yano S, Iizumi Y. Comparative studies of a humanized anti-glycoprotein IIb/IIIa monoclonal antibody, YM337, and abciximab on in vitro antiplatelet effect and binding properties. Biol Pharm Bull 2002; 25:1006-12. [PMID: 12186399 DOI: 10.1248/bpb.25.1006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of YM337, the Fab fragment of a humanized anti-glycoprotein IIb/IIIa (GPIIb/IIIa) monoclonal antibody C4G1, on in vitro platelet function and binding properties were compared with those of abciximab, the Fab fragment of the human/murine chimeric anti-GPIIb/IIIa monoclonal antibody 7E3. Both agents completely inhibited platelet aggregation caused by all agonists tested except ristocetin. Further, both inhibited human platelet adhesion to von Willebrand factor, fibrinogen, fibronectin and subendothelial matrix with similar potency. Fibrinogen binding to washed platelets was dose-dependently inhibited by both agents. In binding assay using 125I-YM337 and 125I-abciximab, Kd values determined with platelet-rich plasma were 6.74 +/- 0.56 nM for YM337 and 6.65 +/- 1.45 nM for abciximab, and the number of binding sites were 42,700 +/- 3,000 for YM337 and 76,000 +/- 5,400 for abciximab. GPIIb/IIIa was precipitated from the solubilized fraction of platelets by both agents. In contrast, integrin alphavbeta3 was precipitated from the solubilized fraction of human umbilical vein endothelial cells by abciximab but not by YM337. Fibrinogen binding to purified GPIIb/IIIa was dose-dependently inhibited by both agents. In contrast, vitronectin binding to purified integrin alphavbeta3 was dose-dependently inhibited by abciximab but not by YM337, supporting the idea that abciximab reacts to integrin alphavbeta3. Therefore, YM337 was suggested to bind to a different epitope of GPIIb/IIIa from abciximab. These results suggest that YM337 specifically acts on platelet GPIIb/IIIa receptors and has similar inhibitory properties on platelet aggregation and platelet adhesion to abciximab.
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Affiliation(s)
- Ken-ichi Suzuki
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co, Ltd, Tsukuba, Ibaraki, Japan.
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Suzuki KI, Moritani Y, Hisamichi N, Ichihara M, Akamatsu S, Arai H, Matsushima H, Nii T, Sato K, Taniuchi Y, Shigenaga T, Kaku S, Kawasaki T, Matsumoto Y, Inagaki O, Tomioka K, Yanagisawa I. Pharmacodynamics and pharmacokinetics of YM128, a GPIIb/IIIa antagonist prodrug. Drug Dev Res 2002. [DOI: 10.1002/ddr.10047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Scheibler L, Mierke DF, Bitan G, Rosenblatt M, Chorev M. Identification of a contact domain between echistatin and the integrin alpha(v)beta(3) by photoaffinity cross-linking. Biochemistry 2001; 40:15117-26. [PMID: 11735394 DOI: 10.1021/bi0109156] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The integrin alpha(v)beta(3) is the major receptor mediating the attachment of osteoclasts to the extracellular matrix in bone and plays a critical role in bone resorption and bone remodeling. Most of the ligands interacting with the alpha(v)beta(3) receptor contain an Arg-Gly-Asp (RGD) motif. Recently, we have identified two small RGD peptides, containing a benzophenone moiety at either the carboxyl or amino terminus, that photo-cross-linked within the beta(3)[99-118] [Bitan, G., et al. (1999) Biochemistry 38, 3414-3420] or the beta(3)[167-171] [Bitan, G., et al. (2000) Biochemistry 39, 11014-11023] sequence, respectively, of the alpha(v)beta(3) receptor in a selective fashion. Here, we report the synthesis of a photoreactive analogue of echistatin (a 49-amino acid peptide), a potent RGD-containing antagonist of the alpha(v)beta(3) receptor both in vitro and in vivo. This bioactive analogue is substituted at position 45 with a p-benzoyl moiety (pBz(2)), located within the flexible C-terminal domain and removed 20 amino acid residues from the R(24)GD(26) triad. This C-terminal domain was reported to contribute to receptor binding affinity by acting as an auxiliary binding site. The radiolabeled (125)I-[Arg(35),Lys(45)(N(epsilon)-pBz(2))]-echistatin photo-cross-links effectively to a site within the beta(3)[209-220] sequence. Residues in this domain have been reported to be part of the metal ion-dependent adhesion site (MIDAS). Receptor fragments overlapping this domain were reported to bind to fibrinogen and block fibrinogen binding to alpha(IIb)beta(3), the platelet integrin receptor. Taken together, position 45 in echistatin, located within an auxiliary binding site in echistatin, cross-links to a site distinct from the two previously reported sites, beta(3)[99-118] and beta(3)[167-171], which cross-link to photophores flanking the RGD triad. These cross-linking data support the hypothesis that the ligand-bound conformation of the integrin beta(3) subunit differs from the known conformation of I domains.
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Affiliation(s)
- L Scheibler
- Division of Bone and Mineral Metabolism, Charles A. Dana and Thorndike Laboratories, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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Nagashima S, Akamatsu S, Kawaminami E, Kawazoe S, Ogami T, Matsumoto Y, Okada M, Suzuki KI, Tsukamoto SI. Novel malonamide derivatives as alpha v beta 3 antagonists. Syntheses and evaluation of 3-(3-indolin-1-yl-3-oxopropanoyl)aminopropanoic acids on vitronectin interaction with alpha v beta 3. Chem Pharm Bull (Tokyo) 2001; 49:1420-32. [PMID: 11724232 DOI: 10.1248/cpb.49.1420] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In attempt to find novel integrin alphavbeta3 antagonists, we selected SC65811 and its guanidine analogue (1) as lead compounds. Modification of the glycine part of SC65811 led to a new series of malonamide derivatives that exhibited alphavbeta3 inhibitory activity. Among them, (R,S)-3-[3-[6-(3-benzylureido)indolin-1-yl]-3-oxopropanoylamino]-3- (pyridin-3-yl)propanoic acid (43a) showed not only potent activity with an IC50 value of 3.0 nM but also good selectivity for alphavbeta3 relative to alphaIIbbeta3, alpha5beta1, and alphavbeta5 with IC50 values of 19,000, 11,000, and 14 nM, respectively. Furthermore, optimization of 43a led to the most potent alphavbeta3 antagonist, (R,S)-3-(3-[6-[(4,5-dihydro-1H-imidazol-2-yl)amino]indolin-1-yl]-3-oxopropanoylamino)-3-(quinolin-3-yl)propanoic acid (431) with an IC50 value of 0.42 nM. The synthesis and the structure-activity relationships of these malonamide derivatives are presented.
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Affiliation(s)
- S Nagashima
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co Ltd, Tsukuba, Ibaraki Japan.
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Bitan G, Scheibler L, Mierke DF, Rosenblatt M, Chorev M. Ligand-integrin alpha v beta 3 interaction determined by photoaffinity cross-linking: a challenge to the prevailing model. Biochemistry 2000; 39:11014-23. [PMID: 10998238 DOI: 10.1021/bi000877a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Integrin alpha(V)beta(3) plays a crucial role in angiogenesis, apoptosis, and bone remodeling, mainly by interacting with matrix proteins through recognition of an Arg-Gly-Asp (RGD) motif. Recently, a small cyclic RGD-containing alpha(V)beta(3)-ligand possessing a C-terminal photoreactive group was photo-cross-linked within beta(3)[99-118], in the N-terminus of the beta(3) chain [Bitan G et al. (1999) Biochemistry 38, 3414-3420]. In this paper, a photoreactive group at the N-terminus of the RGD-ligand is shown to interact within beta(3)[167-171], approximately 60 residues C-terminal to the previously identified domain. On the basis of these findings, a model of the putative I-like domain of the beta(3) subunit, homologous to alpha(M)-, alpha(L)-, and alpha(2)-I-domains, reveals that the beta(3)[99-118] and beta(3)[167-171] contact sites are close to each other and are on the opposite side relative to the metal ion-dependent adhesion site (MIDAS) motif. These observations contradict the prevailing model that proposes proximity between metal- and RGD-binding sites on the I-like domain. Our data suggest that either the I-like domain structure predicted for beta(3) is incorrect, or there is no spatial proximity between the RGD-binding site and the MIDAS motif in the I-like domain. Our results indicate that the current models for ligand-receptor interaction should be revisited.
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Affiliation(s)
- G Bitan
- Division of Bone and Mineral Metabolism, Charles A. Dana and Thorndike Laboratories, Department of Medicine, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, Massachusetts 02215, USA
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Kaku S, Umemura K, Yano S, Suzuki KI, Kawasaki T, Nakashima M. YM337, A platelet glycoprotein IIb/IIIa antagonist, lessens photochemically-induced ischemic brain damage in monkeys. Drug Dev Res 1999. [DOI: 10.1002/(sici)1098-2299(199908)47:4<162::aid-ddr2>3.0.co;2-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kaku S, Umemura K, Mizuno A, Yano S, Suzuki K, Kawasaki T, Nakashima M. Evaluation of a GPIIb/IIIa antagonist YM337 in a primate model of middle cerebral artery thrombosis. Eur J Pharmacol 1998; 345:185-92. [PMID: 9600636 DOI: 10.1016/s0014-2999(98)00005-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We compared the antithrombotic effect of anti-GPIIb/IIIa antibody Fab fragment YM337 with that of a thromboxane A2 synthetase inhibitor, sodium ozagrel. With the monkeys under halothane anesthesia, the right middle cerebral artery was observed via a transorbital approach without cutting the dura mater. Photoillumination (wavelength 540 nm) was applied to the middle cerebral artery, and then rose bengal (20 mg kg(-1)) was administered intravenously. The experimental drugs were intravenously injected 15 min before rose bengal injection and followed by continuous infusion for 3 h after dye injection. The thrombotic occlusion induced by this photochemical reaction in monkey middle cerebral artery was reproducible. YM337 significantly prolonged the time to first occlusion and the total time of arterial patency during the 3-h observation period after dye injection. In contrast, sodium ozagrel had no significant effect. YM337 but not sodium ozagrel significantly inhibited ex vivo ADP-induced platelet aggregation. However, while sodium ozagrel significantly inhibited the thromboxane B2 generation accompanying arachidonic acid-induced platelet aggregation, YM337 had no effect on this variable. Neurological deficit in the YM337-treated animals was significantly milder than that in the control group. The area of infarct in the YM337 treatment animals was smaller than that in the control group. The novel selective GPIIb/IIIa antagonist YM337 was effective in ameliorating the decrease in patency of the middle cerebral artery and reducing the area of cerebral infarction in monkeys.
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Affiliation(s)
- S Kaku
- Department of Pharmacology, Hamamatsu University School of Medicine, Japan.
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Suzuki K, Sakai Y, Hisamichi N, Taniuchi Y, Sato K, Terazaki C, Kaku S, Kawasaki T, Yano S, Inagaki O, Masuho Y. Comparison of the antiplatelet effect of YM337 and abciximab in rhesus monkeys. Eur J Pharmacol 1997; 336:169-76. [PMID: 9384230 DOI: 10.1016/s0014-2999(97)01241-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We directly compared the effects of YM337, the Fab fragment of the humanized monoclonal antibody C4G1, on platelet aggregation and template bleeding time with those of abciximab, the Fab fragment of the human/murine chimeric monoclonal antibody 7E3, in rhesus monkeys. The duration of inhibition of platelet aggregation by abciximab after i.v. bolus injection was much longer than that by YM337. Although YM337 significantly prolonged template bleeding time at 5 min after i.v. bolus injection, this action recovered within 1 h after injection. In contrast, although abciximab also prolonged template bleeding time, the duration of this effect was sustained. In a dose-escalating continuous infusion study, we evaluated the relationship between inhibition of platelet aggregation and prolongation of template bleeding time. Platelet aggregation was inhibited by over 80% by both agents at 3 microg/kg per min, and template bleeding time was prolonged to about 30 min at 30 microg/kg per min for YM337 and 10 microg/kg per min for abciximab. Interestingly, plasma concentrations between inhibition of platelet aggregation and prolongation of template bleeding time did not overlap with YM337, but did overlap with abciximab. These results suggest that YM337 allows easier control of antiplatelet activity with less effect on bleeding time than abciximab, and has a wider therapeutic window than abciximab.
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Affiliation(s)
- K Suzuki
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical, Tsukuba, Ibaraki, Japan.
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Yokoyama K, Handa M, Oda A, Katayama M, Fujimura Y, Murata M, Kawai Y, Watanabe K, Ikeda Y. Characterization of the novel murine monoclonal anti-von Willebrand factor (vWf) antibody GUR76-23 which inhibits vWf interaction with alpha IIb beta 3 but not alpha v beta 3 integrin. Biochem Biophys Res Commun 1997; 234:147-52. [PMID: 9168979 DOI: 10.1006/bbrc.1997.6605] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
von Willebrand factor (vWf) is known to interact with the two beta 3 integrins, alpha IIb beta 3 and alpha v beta 3, in an RGD-dependent manner. We characterized a novel murine monoclonal antibody to human vWf, GUR76-23, which recognized a site within the carboxy-terminal half of the molecule containing the RGD sequence. This antibody inhibited high shear-induced platelet aggregation and blocked adhesion of ADP plus epinephrine-stimulated platelets to vWf, indicating that it interferes with the interaction with alpha IIb beta 3. Unlike antibodies against the RGD site, however, the antibody was without effect on adhesion of cultured human umbilical vein endothelial cells to vWf, a phenomenon known to involve the interaction with alpha v beta 3. GUR76-23 binding was not displaced by anti-RGD antibodies. These results suggest that the adhesive interaction of vWf with these two beta 3 integrins may be differentially modulated by a site(s) other than the common RGD module.
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Affiliation(s)
- K Yokoyama
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
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Banno Y, Nakashima S, Ohzawa M, Nozawa Y. Differential translocation of phospholipase C isozymes to integrin-mediated cytoskeletal complexes in thrombin-stimulated human platelets. J Biol Chem 1996; 271:14989-94. [PMID: 8663010 DOI: 10.1074/jbc.271.25.14989] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
To investigate a role of phospholipase C (PLC) isozymes in the integrin alphaIIbbeta3-mediated signaling, their location was examined in thrombin-activated human platelets, revealing different regulation of their translocation to the cytoskeleton (CSK). In resting platelets, the major PLCs such as PLCbeta2, PLCbeta3a (155 kDa), and PLCgamma2 and the minor PLCs (PLCbeta1 and PLCgamma1) were located in the Triton X-100-soluble (Tx.Sol) fraction and the membrane skeleton, whereas PLCbeta3b (140 kDa) was present only in Tx.Sol fraction when examined by Western immunoblotting. Thrombin stimulation caused a rapid and transient translocation of PLCbeta3a and PLCbeta3b and a slower accumulation of PLCbeta2 and PLCgamma2 in the reorganized CSK. The translocation to CSK of both PLCbeta3a and PLCbeta3b, but not PLCbeta2, was dependent on integrin alphaIIbbeta3-mediated aggregation. Furthermore, an actin polymerization inhibitor, cytochalasin D, or a protein tyrosine kinase inhibitor, genistein, abolished the CSK association of alphaIIbbeta3, PLCbeta3a, and PLCbeta3b. In the genistein-pretreated platelets, pp60(c-)src, Gq, and protein kinase Calpha were no longer able to associate with CSK. In contrast, these agents had no or marginal inhibitory effects on the CSK association of PLCbeta2 and Gi2. The late diacylglycerol generation induced by thrombin stimulation was significantly reduced by the genistein treatment. These results suggest that the integrin alphaIIbbeta3-mediated cytoskeletal association of PLCbeta3 is regulated by protein tyrosine kinase and also that the activation of the relocated PLC may play a role in the late platelet-to-platelet aggregation in thrombin-stimulated human platelets.
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Affiliation(s)
- Y Banno
- Department of Biochemistry, Gifu University School of Medicine, Tsukasamashi-40, Gifu 500, Japan
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Kaku S, Yano S, Kawasaki T, Sakai Y, Suzuki K, Kawamura K, Masuho Y, Satoh N, Takenaka T, Landolfi NF, Co MS. Comparison of the antiplatelet agent potential of the whole molecule, F(ab)2 and Fab fragments of humanized anti-GPIIb/IIIa monoclonal antibody in monkeys. GENERAL PHARMACOLOGY 1996; 27:435-9. [PMID: 8723521 DOI: 10.1016/0306-3623(95)02057-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
1. The potential antiplatelet agent use of the whole molecule, F(ab)2 and Fab fragments of humanized antiglycoprotein (GP) IIb/IIIa monoclonal antibody, hC4G1, were investigated in rhesus monkeys. 2. Fab completely inhibited platelet aggregation 1 hr after an i.v. bolus administration of 1 mg/kg without a decrease in platelet count or prolongation of bleeding time, and the duration of inhibition was much shorter than that of F(ab)2. 3. These results suggest that the Fab fragment of hC4G1 may be a more useful antiplatelet agent in patients with acute thromboembolic diseases than the whole molecule or F(ab)2 fragments.
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Affiliation(s)
- S Kaku
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., Ibaraki, Japan
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Kawasaki T, Sakai Y, Taniuchi Y, Sato K, Maruyama K, Shimizu M, Kaku S, Yano S, Inagaki O, Tomioka K, Yanagisawa I, Takenaka T. Biochemical characterization of a new disintegrin, flavostatin, isolated from Trimeresurus flavoviridis venom. Biochimie 1996; 78:245-52. [PMID: 8874799 DOI: 10.1016/0300-9084(96)82187-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We biochemically characterized a new disintegrin, flavostatin, isolated from Trimeresurus flavoviridis venom. Flavostatin inhibited ADP-, collagen-, and thrombin receptor agonist peptide-induced platelet aggregation in human platelet-rich plasma (IC50 range: 59 to 111 nM) and blocked the binding of biotinylated human fibrinogen to purified GPIIb/IIIa with an inhibitory potency 31,000-fold higher than that of Arg-Gly-Asp-Ser (RGDS). Flavostatin strongly inhibited high-shear-stress-induced platelet aggregation in platelet-rich plasma (PRP) with an IC50 value of 188 nM. Fluorescein isothiocyanate (FITC)-conjugated flavostatin saturably bound to unstimulated and ADP-stimulated washed platelets with high affinity (Kd values: 38 and 21 nM, respectively); the corresponding number of binding sites was 86460 and 79192 per platelet. In competition experiments with several glycoprotein IIb/IIIa antagonists, the binding of FITC-conjugated flavostatin to platelets was completely inhibited by ReoPro, triflavin, TP9201, MK383 and GR144053, but not by YM207, YM337 and B6A3.
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Affiliation(s)
- T Kawasaki
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co Ltd, Ibaraki, Japan
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Yano S, Kaku S, Suzuki K, Terazaki C, Sakayori T, Kawasaki T, Kawamura K, Sugita Y, Hoshino K, Masuho Y. Natural antibodies against the immunoglobulin F(ab')2 fragment cause elimination of antigens recognized by the F(ab')2 from the circulation. Eur J Immunol 1995; 25:3128-33. [PMID: 7489753 DOI: 10.1002/eji.1830251121] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A humanized monoclonal IgG1 antibody, designated hC4G1, recognizes the fibrinogen receptor glycoprotein (GP)IIb/IIIa on platelets and inhibits platelet aggregation. When the F(ab')2 fragment of hC4G1 (F(ab')2 hC4G1) was administered to cynomolgus monkeys, all the monkeys showed inhibition of platelet aggregation ex vivo. Unexpectedly, a significant decrease in platelet count was observed in 5 of 18 monkeys. Antibodies against F(ab')2 hC4G1 were detected in the plasma of these monkeys by ELISA. Antibody activity in the plasma of these monkeys was significantly correlated with the intensity of platelet decrease (r = 0.84). The natural monkey antibodies to F(ab')2 hC4G1 were directed against the C-terminal region of F(ab')2 fragment common to all human and humanized IgG antibodies. Natural homo-reactive antibodies were also detected in human plasma from 15 of 40 healthy volunteers. Specificity was closely similar to that of the monkey antibodies. Affinity-purified human homoreactive antibodies enhanced phagocytosis of platelets treated with the F(ab')2 hC4G1. Monkey plasma with high homo-reactive antibody activity was confirmed to decrease platelet count when administered together with F(ab')2 hC4G1 to a monkey with low antibody activity. These results suggest that F(ab')2 of humanized and human antibodies causes elimination of the corresponding antigens from the circulation by homo-reactive antibodies.
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Affiliation(s)
- S Yano
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., Tsukuba City, Japan
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Kaku S, Kawasaki T, Sakai Y, Taniuchi Y, Yano S, Suzuki K, Terazaki C, Kawamura K, Masuho Y, Satoh N. Antithrombotic effect of a humanized anti-GPIIb/IIIa monoclonal antibody, YM207, in a photochemically induced thrombosis model in monkeys. Eur J Pharmacol 1995; 279:115-21. [PMID: 7556391 DOI: 10.1016/0014-2999(95)00136-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We investigated the antithrombotic effects of a F(ab')2 fragment of a humanized anti-platelet glycoprotein (GP) IIb/IIIa monoclonal antibody, YM207, in a platelet-rich thrombosis model. Thrombus was induced in a mesenteric venule of squirrel monkeys by irradiation with filtered light in combination with i.v. administration of a fluorescent dye (sodium fluorescein). Time to occlusive thrombus formation was significantly prolonged by i.v. bolus injection of 0.3 mg/kg of YM207. At doses of 1 mg/kg and 3 mg/kg, complete occlusion did not occur during 60 min of the observation. Platelet aggregation in platelet-rich plasma was inhibited by YM207 at doses 0.3 mg/kg or more. A good correlation was obtained between inhibition of platelet aggregation and the percentage of GPIIb/IIIa receptors blocked by YM207. Bleeding time was significantly prolonged at a dose of 3 mg/kg. Platelet counts showed no significant change. These results suggest that YM207 is effective in preventing platelet-rich thrombus formation without inducing the prolongation of bleeding time or a significant decrease in platelet count. YM207 may be a useful therapeutic agent for the treatment of thrombotic disorders.
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Affiliation(s)
- S Kaku
- Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., Ibaraki, Japan
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