Identification and recombinant expression of peptides binding to EGFRvIII receptor for targeting of EGFRvIII expressing cancers

Abstract

Epidermal growth factor receptor (EGFR) plays a crucial role in embryogenesis, cell growth, differentiation and migration under normal physiological conditions. However, when mutated, EGFR can lead to malignancies of the brain, breast, lung, ovary, pancreas and the colon. Particularly, the deletion of exons 2-7 makes the receptor to bypass ligand activation tuning it constitutively active that contributes to an extreme aggressiveness ultimately leading to a poor prognosis in various cancers. For instance, in Glioblastoma multiforme (GBM), an aggressive type of brain cancer, the mutated EGFR termed as EGFRvIII is highly prevalent in 25-33% of patients. These patients often have an overall survival of only ~3-6 months, despite surgical resection, chemotherapy or radiotherapy. This is because, these conventional therapies do not address the EGFRvIII mutation that critically drives the pathogenesis leading to the poor prognosis. To improve the patient survival and to minimize the off-target toxicity in EGFRvIII positive patients, tumor-targeted therapies using CART cells, vaccines and antibodies are attempted; however, the treatment modalities are limited by tumor recurrence, adverse effects and insufficient tissue penetration, respectively. Thus, there is an unmet clinical need for developing effective EGFRvIII-targeted therapy where the mutated receptor shall be exploited as a target antigen, because, the expression of EGFRvIII is specific to tumors and hence the possibility of a safe and effective anti-tumor therapy is possible.Thus, the main aim of this work is to develop an effective biologics-based approach for the targeted therapy of EGFRvIII receptor overexpressing cancers such as GBM.To realize this,phage display technology was exploited in two different strategies to identify EGFRvIII targeting peptides.In the 1st approach, phage displayed antibody fragments of an anti-EGFRvIII antibody were screened by whole cell ELISA and an EGFRvIII binding peptide- H13 (15 kDa) was identified.Thereafter this peptide..