Anti-EGFRvIII scFvs with improved cytotoxicity and yield, immunotoxins based thereon, and methods of use thereof

摘要

Antibodies for a mutant form of the epidermal growth factor receptor known as EGFRvIII are described. This mutant is found only or primarily on the surface of glioblastoma cells, and on cells of breast, ovarian and non-small cell lung carcinomas. The antibodies described have higher affinity for EGFRvIII, and form immunotoxins with higher cytotoxicity and yield, than prior art antibodies, including the scFv designated MR1. In particular, an antibody, designated MR1-1 is provided, which mutates MR1 in the CDR3 of the VH and VL chains to make an antibody with especially good cytotoxicity. Additional antibodies are also described in which MR1 is mutated in the CDR1 and 2 of VH or VL, or both, with better binding to EGFRvIII than that of the parental MR1 antibody. Depicted in the graph is the survival of athymic rats with neoplastic meningitis following intrathecal injection of human glioblastoma cells transfected with EGFRvIII and treated with MR1-1-targeted immunotoxin or saline control. The Y-axis shows the percentage of animals surviving at a given point in time. The X-axis shows the survival time in days.