Noguchi-Sasaki Mariko, Soeda Tetsuhiro, Ueyama Atsunori, Muto Atsushi, Hirata Michinori, Kitamura Hidetomo, Fujimoto-Ouchi Kaori, Kawabe Yoshiki, Nogami Keiji, Shima Midori, Kitazawa Takehisa
Medical Affairs Division, Chugai Pharmaceutical Co., Ltd., Kamakura, Kanagawa, Japan.
Research Division, Chugai Pharmaceutical Co., Ltd., Gotemba, Shizuoka, Japan.
TH Open. 2018 Mar 16;2(1):e96-e103. doi: 10.1055/s-0038-1636538. eCollection 2018 Jan.
Emicizumab is a humanized bispecific antibody that binds simultaneously to factor (F) IXa and FX replacing the cofactor function of FVIIIa. Because emicizumab recognizes FIX/FIXa and FX/FXa, a question may arise whether emicizumab competes with antithrombin (AT) and/or tissue factor pathway inhibitor (TFPI), thereby enhancing overall hemostatic potential by blocking their antihemostatic effects. To address this question, we performed enzymatic assays using purified coagulation factors to confirm whether emicizumab interferes with the action of AT on FIXa or FXa, or with the action of TFPI on FXa. In those assays, we found no interference of emicizumab on the actions of AT and TFPI. We next assessed emicizumab's influences on the anticoagulation actions of AT or TFPI in thrombin generation assays triggered with FXIa or tissue factor (TF) in AT-depleted or TFPI-depleted plasma supplemented with AT or TFPI in vitro. In those assays, we employed anti-FIXa and anti-FX monospecific one-armed antibodies derived from emicizumab instead of emicizumab itself so as to prevent emicizumab's FVIIIa cofactor activity from boosting thrombin generation. Consequently, we found that neither anti-FIXa, anti-FX monospecific antibody, nor the mixture of the two interfered with the anticoagulation actions of AT or TFPI in plasma. Although emicizumab can bind to FIXa and FXa, our results showed no interference of emicizumab with the action of AT or TFPI on FIXa or FXa. This indicates that the presence of emicizumab is irrelevant to the action of AT and TFPI, and thus should not alter the coagulant/anticoagulant balance related to AT and TFPI.
艾美赛珠单抗是一种人源化双特异性抗体，可同时结合因子（F）IXa和FX，替代FVIIIa的辅因子功能。由于艾美赛珠单抗可识别FIX/FIXa和FX/FXa，因此可能会产生一个问题，即艾美赛珠单抗是否会与抗凝血酶（AT）和/或组织因子途径抑制剂（TFPI）竞争，从而通过阻断它们的抗止血作用来增强整体止血潜力。为了解决这个问题，我们使用纯化的凝血因子进行了酶学测定，以确认艾美赛珠单抗是否会干扰AT对FIXa或FXa的作用，或者干扰TFPI对FXa的作用。在这些测定中，我们发现艾美赛珠单抗不会干扰AT和TFPI的作用。接下来，我们在体外补充了AT或TFPI的AT缺乏或TFPI缺乏的血浆中，用FXIa或组织因子（TF）引发的凝血酶生成测定中评估了艾美赛珠单抗对AT或TFPI抗凝作用的影响。在这些测定中，我们使用了源自艾美赛珠单抗的抗FIXa和抗FX单特异性单臂抗体，而不是艾美赛珠单抗本身，以防止艾美赛珠单抗的FVIIIa辅因子活性促进凝血酶生成。因此，我们发现抗FIXa、抗FX单特异性抗体或两者的混合物均不会干扰血浆中AT或TFPI的抗凝作用。虽然艾美赛珠单抗可以与FIXa和FXa结合，但我们的结果表明，艾美赛珠单抗不会干扰AT或TFPI对FIXa或FXa的作用。这表明艾美赛珠单抗的存在与AT和TFPI的作用无关，因此不应改变与AT和TFPI相关的凝血/抗凝平衡。
