title: The novel EpCAM-targeting monoclonal antibody 3-17I linked to saporin is highly cytotoxic after photochemical internalization in breast, pancreas and colon cancer cell lines.
abstract: The epithelial cell adhesion molecule (EpCAM) is expressed by a wide range of human carcinomas, making it an attractive diagnostic and therapeutic target in oncology. Its recent identification on cancer stem cells has raised further interest in its use for tumor targeting and therapy. Here, we present the characterization and therapeutic potential of 3-17I, a novel human EpCAM-targeting monoclonal antibody. Strong reaction of 3-17I was observed in all lung, colon, and breast human tumor biopsies evaluated. By flow cytometry and confocal fluorescence microscopy, we demonstrate that 3-17I specifically targets EpCAM-positive cell lines. We also show evidence for mAb-sequestration in endo-/lysosomes, suggesting internalization of 3-17I by receptor-mediated endocytosis. The ribosomal-inactivating toxin saporin was linked to 3-17I, creating the per se non-toxic immunotoxin 3-17I-saporin, a promising candidate for the drug delivery technology photochemical internalization (PCI). PCI is based on a light-controlled destruction of endolysosomal membranes and subsequent cytosolic release of the sequestered payload upon light exposure. EpCAM-positive human cancer cell lines MCF7 (breast), BxPC-3 (pancreas), WiDr (colon), and the EpCAM-negative COLO320DM (colon), were treated with 3-17I-saporin in combination with the clinically relevant photosensitizer TPCS2a (Amphinex), followed by exposure to light. No cytotoxicity was observed after treatment with 3-17I-saporin without light exposure. However, cell viability, proliferation and colony-forming capacity was strongly reduced in a light-dependent manner after PCI of 3-17I. Our results show that 3-17I is an excellent candidate for diagnosis of EpCAM-positive tumors and for development of clinically relevant antibody-drug conjugates, using PCI for the treatment of localized tumors.
authors: Kaja
authors: K
authors: Lund
authors: Monica
authors: M
authors: Bostad
authors: Ellen
authors: E
authors: Skarpen
authors: Michael
authors: M
authors: Braunagel
authors: Sergej
authors: S
authors: Kiprijanov
authors: Stefan
authors: S
authors: Krauss
authors: Alex
authors: A
authors: Duncan
authors: Anders
authors: A
authors: Høgset
authors: Pål K
authors: PK
authors: Selbo
mesh_terms: D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000276:immunology / Q000494:pharmacology*; D000912:Antibodies, Neoplasm / Q000276:immunology / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D016503:Drug Delivery Systems / Q000379:methods; D005260:Female; D006801:Humans; D000922:Immunotoxins / Q000276:immunology / Q000494:pharmacology*; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D010777:Photochemistry / Q000379:methods; D054789:Ribosome Inactivating Proteins, Type 1 / Q000276:immunology / Q000494:pharmacology*; D000076985:Saporins
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D000912:Antibodies, Neoplasm; D000922:Immunotoxins; D054789:Ribosome Inactivating Proteins, Type 1; D000076985:Saporins