【作者】 厉保秋； 杨志坚； Takayaki； 朱振平； 于丽华；

【Author】 Bao qiu Li,Zhijian Yang, Takayuki Yoshioka, Zhuzheng Ping Toxicology Research Center, Shangdong University, Jinan 250012; AntiCancer, Inc., San Diego, California; Shionogi and Co., Ltd., Osaka, Japan.

【机构】 山东大学毒理学研究所； AntiCancerInC.,SandiegoUSA； ShionogiCo.Ltd.,Osaka,Japan；

【摘要】 目的重组蛋氨酸酶(rMETase)对于人系外源性蛋白酶,该酶在人肿瘤裸鼠模型中表现出广泛的抑瘤作用。本实验以灵长类动物猕猴为研究对象,测定了rMETase的药代动力学、免疫原性和/或免疫毒性及系统毒性。方法与结果rMETase单次静脉注射1000u/kg、2000u/kg和4000u/kg时,猕猴血浆蛋氨酸水平在30min内可降低至无法检测的水平(小于0.5umol/L),且持续4h;给药剂量4000u/kg时,血浆蛋氨酸低于1umol/L的水平,可维持8h。rMETase在猕猴体内的T1/2为2.49 h,给药2000u/kg和4000u/kg时的CL分别为11.28ml/h 和30.77ml/h;rMETase以4000u/(kg·8h)重复给药2周时,可使血浆蛋氨酸水平在给药期间维持在2μmol/L以下:重复大剂量给药的主要系统毒性表现为食量减少、体重轻微下降, 血浆白蛋白和红细胞水平呈可逆性降低。当rMETase重复给药2周后的第28d再次给药时, 出现过敏性休克。其中有1只动物死亡:及时给予激素抢救可避免死亡,或给药前给予氢化可的松可预防过敏性休克发生,在实验的第66、86和116天时再次给药,首次给药后抗rMETase抗体水平为103。第4次给药后增加到10-6;在以后的2个月内抗体水平降低至102。抗rMETase抗体类型主要是IgG,体外检测系中和性抗体:但在体内对rMETase降低血浆蛋氨酸作用的影响较小。结论系统研究表明,rMETase在猕猴模型中能有效地降低血浆中蛋氨酸水平,出现的系统毒性反应很小;rMETase是一具良好前景的广谱抗肿瘤新药,但应重视其免疫原性,如能进行化学修饰或其它处理则可增加药物的作用时间并降低其免疫原性, 增加用药安全性。更多还原

【Abstract】 Objective Pharmacokinetics, methionine depletion, antigenicity,and toxicity of recombinant methioninase(rMETase), which has shown efficacy in achieving cell kill in a broad range of human tumor models, were examined in macaque monkeys. Method and Result Dose-ranging studies at 1000,2000 and 4000 units/kg i. v. identified the 4000 units/kg dose as able to reduce plasma methionine to an undetectable level (less than 0. 5μM) by 30min, and the level so remained for 8h. Pharmacokinetic analysis showed that rMETase was eliminated with a T1/2 of 2. 49h. A 2-week i. v. administration of 4000 units/kg every 8h/day for 2 week sresulted in a steady-state depletion of plasma methionine to less than 2μM. The only manifest toxicity was decreased food intake and slight weight loss. Serum albumin and red cell values declined transiently during treatment, which may be related to extensive blood sampling. Re-challenge on day 28 resulted in anaphylactic shock and death in one animal. Subsequent pretreatment with hydrocortisone prevented the anaphylactic reaction, although vomiting was frequently observed. Re-challenge was carried out at days 66,86 and 116. Anti-rMETase antibodies(at 10-3) were found after the first challenge, and these increased to 10-6 after the fourth challenge and decreased to 10-2 by 2 months post therapy. The main rMETase antibody was IgG, and although it has some in vitro features of being a neutralizing antibody, each challenge dose was effective in depleting plasma methionine levels. Thus, rMETase was able to effectively deplete plasma methionine levels with minimal toxicity in a primate model. Conclusion These data provide the bases for alteration by polyethyleneglycol conjugation(PEGylation) of the enzyme to increase its duration of effect and reduce its immunogenicity.更多还原