Kerr D E, Li Z, Siemers N O, Senter P D, Vrudhula V M
Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington 98121, USA.
Bioconjug Chem. 1998 Mar-Apr;9(2):255-9. doi: 10.1021/bc970163l.
The synthesis of C-Mel, a cephalosporin carbamate derivative of the clinically used alkylating agent melphalan, is described. C-Mel was designed as an anticancer nitrogen mustard prodrug that releases melphalan upon tumor-specific activation by targeted beta-lactamase (bL). The Km and kcat values for bL hydrolysis of C-Mel were 218 microM and 980 s(-1), respectively. In vitro cytotoxicity assays with 3677 human melanoma cells demonstrated that C-Mel was 40-fold less toxic than melphalan and was activated in an immunologically specific manner by L49-sFv-bL, a recombinant fusion protein that binds to the melanotransferrin antigen on melanomas and on some carcinomas. L49-sFv-bL in combination with C-Mel led to regressions and cures of established subcutaneous 3677 tumors in nude mice. The effects were significantly greater than those of melphalan, which did not result in any long-term regressions in this tumor model. The therapeutic effects were comparable to those obtained in mice treated with the previously described L49-sFv-bL/7-(4-carboxybutanamido)-cephalosporin mustard (CCM) combination. However, C-Mel may be more attractive than CCM for clinical development since the released drug is clinically approved.
本文描述了C-Mel的合成，它是临床使用的烷化剂美法仑的头孢菌素氨基甲酸酯衍生物。C-Mel被设计为一种抗癌氮芥前药，在肿瘤特异性β-内酰胺酶（bL）激活后释放美法仑。C-Mel经bL水解的Km和kcat值分别为218μM和980 s(-1)。对3677个人类黑色素瘤细胞进行的体外细胞毒性试验表明，C-Mel的毒性比美法仑低40倍，并被L49-sFv-bL以免疫特异性方式激活，L49-sFv-bL是一种重组融合蛋白，可与黑色素瘤和某些癌上的黑色素转铁蛋白抗原结合。L49-sFv-bL与C-Mel联合使用可使裸鼠体内已建立的皮下3677肿瘤消退并治愈。其效果明显优于美法仑，在该肿瘤模型中美法仑未导致任何长期消退。治疗效果与用先前描述的L49-sFv-bL/7-(4-羧基丁酰胺基)-头孢菌素氮芥（CCM）组合治疗的小鼠所获得的效果相当。然而，C-Mel可能比CCM更具临床开发吸引力，因为释放的药物已获临床批准。
