Antibody-drug conjugates (ADC) are spearheading vectorized chemotherapy against cancer, with 4 FDA-approved ADCs and 79 in clinical trials. However, most ADCs are produced using a stochastic bioconjugation method, target hematological cancers, and are derived from a full immunoglobulin-G (IgG). These factors limit their efficacy, especially against solid tumors which remain difficult to treat. Here we report the site-specific conjugation of a single auristatin derivative onto an engineered anti-HER2 single chain fragment variable (scFv) of the trastuzumab antibody, generating new scFv-drug conjugates (SDC). Two cysteines were judiciously incorporated at the beginning of the scFv hexahistidine tag, in order to allow controlled bioconjugation of a heterobifunctional linker including a second generation maleimide (SGM), either cleavable (for monomethyl auristatin E) or noncleavable (for monomethyl auristatin F). Our data indicated that both SDCs conserved their affinity to HER2 in comparison to the native scFv, and were efficiently able to kill in vitro HER2-positive SK-BR-3 cells at subnanomolar concentrations (EC50 of 0.68 nM and 0.32 nM). No effect was observed on HER2-negative MCF-7 cells. Ours results showed efficient targeting of site-specific SDCs against HER2-positive breast cancer cells. This work represents a first important step in the design of more effective small conjugates, paving the way for future in vivo translation to evaluate their full potential.
                                    抗体-药物偶联物(ADC)是抗癌的载体化化疗先锋,目前有4种ADC获得FDA批准,79种ADC正在临床试验中。然而,大多数ADC都是采用随机
生物偶联方法生产的,靶向血液系统癌症,并且源自完整的免疫球蛋白G(IgG)。这些因素限制了ADC的疗效,尤其是对仍然难以治疗的实体瘤。在此,我们报告了一种耳毒蛋白衍
生物与曲妥珠单抗的工程化抗HER2单链片段可变(scFv)的特定位点偶联,从而产生了新的scFv-药物偶联物(
SDC)。为了实现异二元官能团连接子的可控
生物偶联,我们在scFv六组
氨酸标签的开头巧妙地加入了两个半胱
氨酸,其中包含第二代马来
酰亚胺(SGM),可裂解(用于单甲基耳毒蛋白E)或不可裂解(用于单甲基耳毒蛋白F)。我们的数据表明,与天然scFv相比,两种
SDC均保持了与HER2的亲和力,并且能够以亚纳摩尔浓度(
EC50为0.68 nM和0.32 nM)有效杀死体外HER2阳性的SK-BR-3细胞。对HER2阴性的MCF-7细胞没有观察到任何影响。我们的结果表明,特定位点
SDC能够有效靶向HER2阳性的乳腺癌