Discussion

Placental growth factor (PlGF) is a member of the vascular endothelial growth factor (VEGF) family of proteins. It promotes angiogenesis particularly during embryogenesis through its interaction with its receptor VEGF receptor-1 (VEGFR-1) but increased expression is also associated with the growth and spread of some cancers. Therefore an anti PlGF antibody has the potential to be an anti cancer therapeutic drug.

Potent anti PlGF antibodies have been isolated at MedImmune by two approaches in vitro ribosome display and in vivo immunisation. During Lead Isolation ribosome display was used to identify a panel of anti PlGF antibodies however they did not have the desired potency or mouse (63% sequence identity to human) cross reactivity required for in vitro pharmacology studies. The affinity of the ribosome display lead antibody was improved through mutagenesis of the antibody/antigen binding site. In parallel an immunisation approach was undertaken to potentially identify mouse cross reactive antibodies to a different epitope. This poster compares the in vitro assay results for key clones that were identified from the two antibody platforms.