Kaneda Y, Yamamoto Y, Kamada H, Tsunoda S, Tsutsumi Y, Hirano T, Mayumi T
Faculty of Pharmaceutical Sciences, Osaka University, Suita, Japan.
Cancer Res. 1998 Jan 15;58(2):290-5.
The purpose of this study is to further explore the usefulness of conjugation with functional polymeric modifiers for clinical application of bioactive proteins and to increase the therapeutic efficacy of tumor necrosis factor alpha (TNF-alpha) by conjugation in vivo. We synthesized TNF-alpha conjugated with the copolymer of divinyl ether and maleic anhydride (DIVEMA), which has intrinsic antitumor activity as a synthetic biological response modifier. The synthesis of DIVEMA-TNF-alpha could be controlled by the addition of 2,3-dimethylmaleic anhydride (DMMAn), which binds to or separates from amino groups when the pH is changed. The specific activity of DIVEMA-TNF-alpha (+) synthesized with DMMAn was hardly decreased in vitro. However, DIVEMA-TNF-alpha (-), which is conjugated without blocking by DMMAn, had a markedly diminished specific activity. DIVEMA-TNF-alpha (+) caused a dramatic hemorrhagic necrotic effect on the tumor when compared to native TNF-alpha 24 h after i.v. injection into mice bearing Sarcoma-180 solid tumors. In addition, DIVEMA-TNF-alpha (+) at a dose of only 100 Japan reference units per mouse revealed a dramatic antitumor effect that is approximately 100 times greater than native TNF-alpha and that could induce complete regression in all five mice bearing Meth-A solid tumors without any apparent side effects. Because neither DIVEMA alone nor a mixture of TNF-alpha and DIVEMA caused antitumor activity with i.v. administration, the increase in antitumor potency of TNF-alpha may be caused by the covalent conjugation with DIVEMA. DIVEMA-TNF-alpha at low dose revealed dramatic antitumor potency. Because TNF-alpha injected in vivo is extremely low-dose, concentration of intrinsic TNF-alpha in vivo is not influenced. Therefore, the cytokine network in vivo is not destroyed. These results suggest that DIVEMA is a useful polymeric modifier for conjugation of TNF-alpha to increase its antitumor activity.
本研究的目的是进一步探索与功能性聚合物修饰剂结合对于生物活性蛋白临床应用的有用性，并通过体内结合来提高肿瘤坏死因子α（TNF-α）的治疗效果。我们合成了与二乙烯基醚和顺丁烯二酸酐共聚物（DIVEMA）结合的TNF-α，DIVEMA作为一种合成生物反应调节剂具有内在的抗肿瘤活性。DIVEMA-TNF-α的合成可通过添加2,3-二甲基马来酸酐（DMMAn）来控制，当pH值改变时，DMMAn会与氨基结合或分离。用DMMAn合成的DIVEMA-TNF-α（+）在体外其比活性几乎没有降低。然而，未被DMMAn封闭而结合的DIVEMA-TNF-α（-），其比活性则显著降低。与天然TNF-α相比，静脉注射到携带肉瘤180实体瘤的小鼠体内24小时后，DIVEMA-TNF-α（+）对肿瘤产生了显著的出血坏死效应。此外，每只小鼠仅注射100日本参考单位剂量的DIVEMA-TNF-α（+）就显示出显著的抗肿瘤效果，其效果比天然TNF-α大约强100倍，并且可以使所有五只携带Meth-A实体瘤的小鼠完全消退，且没有任何明显的副作用。由于单独的DIVEMA或TNF-α与DIVEMA的混合物静脉给药均未产生抗肿瘤活性，TNF-α抗肿瘤效力的提高可能是由于与DIVEMA的共价结合。低剂量的DIVEMA-TNF-α显示出显著的抗肿瘤效力。由于体内注射的TNF-α剂量极低，因此不会影响体内内源性TNF-α的浓度。因此，体内的细胞因子网络不会被破坏。这些结果表明，DIVEMA是一种用于结合TNF-α以增加其抗肿瘤活性的有用聚合物修饰剂。
