Cell-penetrable nanobodies (transbodies) that inhibit the tyrosine kinase activity of EGFR leading to the impediment of human lung adenocarcinoma cell motility and survival.

Most patients suffering from non-small cell lung cancer (NSCLC) have epidermal growth factor receptor (EGFR) overexpression. Currently, EGFR tyrosine kinase inhibitors (TKIs) that act as the ATP-analogs and monoclonal antibodies (MAbs) to EGFR-ectodomain that block intracellular signaling are used for the treatment of advanced NSCLC. Unfortunately, adverse effects due to the TKI off-target and drug resistance occur in a significant number of the treated patients while some NSCLC genotypes do not respond to the therapeutic MAbs. Thus, a more effective remedy for the treatment of EGFR-overexpressed cancers is deemed necessary. In this study, VH/VH H displayed-phage clones that are bound to recombinant EGFR-TK were fished-out from a humanized-camel VH/VH H phage display library. VH/VH H of three phage-infected Escherichia coli clones (VH18, VH H35, and VH36) were linked molecularly to nonaarginine (R9) for making them cell penetrable. R9-VH18, R9-VH H35, and R9-VH36 were cytotoxic to human adenocarcinomic alveolar basal epithelial cells (A549) at the fifty percent inhibitory concentration (IC50 ) 0.181 ± 0.132, 0.00961 ± 0.00516, and 0.00996 ± 0.00752 µM, respectively, which were approximately 1000-fold more effective than small molecular TKIs. R9-VH18 and R9-VH36 also delayed cancer cell migration in a scratch-wound assay. Computerized homology modeling and intermolecular docking revealed that VH18 and VH H35 used CDR3 to interact with EGFR-TK residues close to the catalytic site, which might sterically hinder the ATP-binding of the TK; VH36 used CDR2 to bind at the asymmetric dimerization surface, which might disrupt EGFR dimerization leading to inhibition of intracellular signaling. The humanized-cell penetrable nanobodies have a high potential for developing further towards a clinical application.