Department of Therapeutic Radiology-Radiation Oncology, Section on Molecular Cancer Therapeutics, University of Minnesota Masonic Cancer Center, MMC: 367, Minneapolis, MN 55455, USA.
J Neurooncol. 2011 Jun;103(2):255-66. doi: 10.1007/s11060-010-0392-5. Epub 2010 Sep 10.
A bispecific ligand-directed toxin (BLT), called EGFATFKDEL, consisting of human epidermal growth factor, a fragment of urokinase, and truncated pseudomonas exotoxin (PE38) was assembled in order to target human glioblastoma. Immunogenicity was reduced by mutating seven immunodominant B-cell epitopes on the PE38 molecule to create a new agent, EGFATFKDEL 7mut. In vitro, the drug selectively killed several human glioblastoma cell lines. EGFATFKDEL is our first BLT designed to simultaneously target EGFR on solid tumors and uPAR on the tumor neovasculature. In vitro assays revealed that the agent is effective against glioblastoma cell lines as well as human umbilical vein endothelial cells (HUVEC). Additionally, the bispecific drug displayed enhanced binding to overexpressed epidermal growth factor receptor and urokinase receptor when compared to similar monospecific drugs, EGFKDEL and ATFKDEL. In vivo, an aggressive human glioblastoma cell line was genetically marked with a firefly luciferase reporter gene and administered to the flanks of nude mice. Treatment with intratumoral injections of EGFATFKDEL 7mut eradicated small tumors in over half of the treated mice, which survived with tumor free status at least 100 days post tumor inoculation. ATFKDEL, which primarily targets the tumor neovasculature, prevented tumor growth but did not result in tumor-free mice in most cases. Specificity was shown by treating with an irrelevant BLT control which did not protect mice. Finally, immunization experiments in immunocompetent mice revealed significantly reduced anti-toxin production in EGFATFKDEL 7mut treated groups. Thus, EGFATFKDEL 7mut is an effective drug for glioblastoma therapy in this murine model and warrants further study.
一种双特异性配体导向毒素（BLT），称为 EGFATFKDEL，由人表皮生长因子、尿激酶片段和截短的假单胞菌外毒素（PE38）组成，旨在靶向人胶质母细胞瘤。通过突变 PE38 分子上的七个免疫优势 B 细胞表位，产生了一种新的药物 EGFATFKDEL 7mut，从而降低了其免疫原性。在体外，该药物选择性地杀死了几种人胶质母细胞瘤细胞系。EGFATFKDEL 是我们设计的第一个同时靶向实体瘤表皮生长因子受体和肿瘤新生血管 uPAR 的 BLT。体外试验表明，该药物对胶质母细胞瘤细胞系和人脐静脉内皮细胞（HUVEC）均有效。此外，与类似的单特异性药物 EGFKDEL 和 ATFKDEL 相比，双特异性药物对过度表达的表皮生长因子受体和尿激酶受体的结合能力增强。在体内，用萤火虫荧光素酶报告基因对侵袭性人胶质母细胞瘤细胞系进行基因标记，并将其接种到裸鼠的侧腹。用 EGFATFKDEL 7mut 瘤内注射治疗，超过一半接受治疗的小鼠的小肿瘤被根除，这些小鼠在肿瘤接种后至少 100 天仍保持无肿瘤状态。ATFKDEL 主要靶向肿瘤新生血管，可阻止肿瘤生长，但在大多数情况下不能使小鼠无肿瘤。用不相关的 BLT 对照物治疗显示出特异性，该对照物不能保护小鼠。最后，在免疫功能正常的小鼠中进行的免疫实验表明，在 EGFATFKDEL 7mut 治疗组中，抗毒素的产生明显减少。因此，EGFATFKDEL 7mut 是该小鼠模型中胶质母细胞瘤治疗的有效药物，值得进一步研究。
