A novel bispecific ligand-directed toxin designed to simultaneously target EGFR on human glioblastoma cells and uPAR on tumor neovasculature

Alexander K. Tsai, Seunguk Oh, Hua Chen, Yanqun Shu, John R. Ohlfest, Daniel A. Vallera

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)255-266
Number of pages12
JournalJournal of neuro-oncology
Issue number2
StatePublished - Jun 2011

Bibliographical note

Funding Information:
Acknowledgments This work was supported in part by the US Public Health Service Grants RO1-CA36725 and RO1-CA082154 awarded by the NCI and the NIAID, DHHS and the Martha L. Kramer Fund. We thank Travis M. Spangler and Zintis Inde for assistance. This manuscript partially fulfilled requirements for the Master of Science degree for A. Tsai, CLS program, University of Minnesota.


  • EGF
  • Glioblastoma
  • Immunotoxin
  • Pseudomonas exotoxin
  • Xenograft model


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