van Beusechem V W, Mastenbroek D C J, van den Doel P B, Lamfers M L M, Grill J, Würdinger T, Haisma H J, Pinedo H M, Gerritsen W R
Division of Gene Therapy, Department of Medical Oncology, The Netherlands.
Gene Ther. 2003 Nov;10(23):1982-91. doi: 10.1038/sj.gt.3302103.
Conditionally replicative adenoviruses (CRAds) are potentially useful agents for anticancer virotherapy approaches. However, lack of coxsackievirus and adenovirus receptor (CAR) expression on many primary tumor cells limits the oncolytic potency of CRAds. This makes the concept of targeting, that is, redirecting infection via CAR-independent entry pathways, relevant for CRAd development. Bispecific adapter molecules constitute highly versatile means for adenovirus targeting. Here, we constructed a CRAd with the Delta24 E1A mutation that produces a bispecific single-chain antibody directed towards the adenovirus fiber knob and the epidermal growth factor receptor (EGFR). This EGFR-targeted CRAd exhibited increased infection efficiency and oncolytic replication on CAR-deficient cancer cells and augmented lateral spread in CAR-deficient 3-D tumor spheroids in vitro. When compared to its parent control with native tropism, the new CRAd exhibited similar cytotoxicity on CAR-positive cancer cells, but up to 1000-fold enhanced oncolytic potency on CAR-deficient, EGFR-positive cancer cells. In addition, EGFR-targeted CRAd killed primary human CAR-deficient brain tumor specimens that were refractory to the parent control virus. We conclude, therefore, that CRAds expressing bispecific targeting adapter molecules are promising agents for cancer treatment. Their use is likely to result in enhanced oncolytic replication in cancerous tissues and thus in more effective tumor regression.
条件性复制腺病毒（CRAds）是抗癌病毒疗法中潜在有用的制剂。然而，许多原发性肿瘤细胞上缺乏柯萨奇病毒和腺病毒受体（CAR）表达限制了CRAds的溶瘤效力。这使得靶向概念，即通过不依赖CAR的进入途径重新引导感染，与CRAd的开发相关。双特异性衔接分子构成了腺病毒靶向的高度通用手段。在这里，我们构建了一种带有Delta24 E1A突变的CRAd，它产生一种针对腺病毒纤维结和表皮生长因子受体（EGFR）的双特异性单链抗体。这种靶向EGFR的CRAd在缺乏CAR的癌细胞上表现出更高的感染效率和溶瘤复制能力，并在体外增强了在缺乏CAR的三维肿瘤球体中的横向扩散。与具有天然嗜性的亲本对照相比，新的CRAd在CAR阳性癌细胞上表现出相似的细胞毒性，但在缺乏CAR、EGFR阳性的癌细胞上溶瘤效力提高了1000倍。此外，靶向EGFR的CRAd杀死了对亲本对照病毒难治的原发性人CAR缺陷脑肿瘤标本。因此，我们得出结论，表达双特异性靶向衔接分子的CRAds是有前途的癌症治疗药物。它们的使用可能会导致在癌组织中增强溶瘤复制，从而更有效地使肿瘤消退。
