title: Design of an EGFR-targeting toxin for photochemical delivery: in vitro and in vivo selectivity and efficacy.
abstract: The number of epidermal growth factor receptor (EGFR)-targeting drugs in the development for cancer treatment is continuously increasing. Currently used EGFR-targeted monoclonal antibodies and tyrosine kinase inhibitors have specific limitations related to toxicity and development of resistance, and there is a need for alternative treatment strategies to maximize the clinical potential of EGFR as a molecular target. This study describes the design and production of a novel EGFR-targeted fusion protein, rGel/EGF, composed of the recombinant plant toxin gelonin and EGF. rGel/EGF was custom-made for administration by photochemical internalization (PCI), a clinically tested modality for cytosolic release of macromolecular therapeutics. rGel/EGF lacks efficient mechanisms for endosomal escape and is therefore minimally toxic as monotherapy. However, PCI induces selective and efficient cytosolic release of rGel/EGF in EGFR-expressing target cells by light-directed activation of photosensitizers accumulated selectively in tumor tissue. PCI of rGel/EGF was shown to be highly effective against EGFR-expressing cell lines, including head and neck squamous cell carcinoma (HNSCC) cell lines resistant to cetuximab (Erbitux). Apoptosis, necrosis and autophagy were identified as mechanisms of action following PCI of rGel/EGF in vitro. PCI of rGel/EGF was further shown as a highly tumor-specific and potent modality in vivo, with growth inhibitory effects demonstrated on A-431 squamous cell carcinoma (SCC) xenografts and reduction of tumor perfusion and necrosis induction in SCC-026 HNSCC tumors. Considering the small amount of rGel/EGF injected per animal (0.1 mg/kg), the presented in vivo results are highly promising and warrant optimization and production of rGel/EGF for further preclinical evaluation with PCI.
authors: Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.
authors: M B
authors: MB
authors: Berstad
authors: Immunopharmacology and Targeted Therapy Laboratory, Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA.
authors: L H
authors: LH
authors: Cheung
authors: Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.
authors: K
authors: K
authors: Berg
authors: Department of Pathology, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.
authors: Q
authors: Q
authors: Peng
authors: Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.
authors: A S V
authors: AS
authors: Fremstedal
authors: Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.
authors: S
authors: S
authors: Patzke
authors: Immunopharmacology and Targeted Therapy Laboratory, Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX, USA.
authors: M G
authors: MG
authors: Rosenblum
authors: Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.
authors: A
authors: A
authors: Weyergang
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000378:metabolism; D045744:Cell Line, Tumor; D000068818:Cetuximab / Q000494:pharmacology; D016503:Drug Delivery Systems / Q000379:methods; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000378:metabolism; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D010777:Photochemistry / Q000379:methods; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D054789:Ribosome Inactivating Proteins, Type 1 / Q000378:metabolism; D000077195:Squamous Cell Carcinoma of Head and Neck; D014118:Toxins, Biological / Q000494:pharmacology*
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D011993:Recombinant Fusion Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D014118:Toxins, Biological; D004815:Epidermal Growth Factor; C025674:GEL protein, Gelonium multiflorum; C512478:EGFR protein, human; D066246:ErbB Receptors; D000068818:Cetuximab