title: Targeting HER2: a report on the in vitro and in vivo pre-clinical data supporting trastuzumab as a radioimmunoconjugate for clinical trials.
abstract: The potential of the HER2-targeting antibody trastuzumab as a radioimmunoconjugate useful for both imaging and therapy was investigated. Conjugation of trastuzumab with the acyclic bifunctional chelator CHX-A"-DTPA yielded a chelate:protein ratio of 3.4 ± 0.3; the immunoreactivity of the antibody unaffected. Radiolabeling was efficient, routinely yielding a product with high specific activity. Tumor targeting was evaluated in mice bearing subcutaneous (s.c.) xenografts of colorectal, pancreatic, ovarian, and prostate carcinomas. High uptake of the radioimmunoconjugate, injected intravenously (i.v.), was observed in each of the models, and the highest tumor %ID/g (51.18 ± 13.58) was obtained with the ovarian (SKOV-3) tumor xenograft. Specificity was demonstrated by the absence of uptake of 111In-trastuzumab by melanoma (A375) s.c. xenografts and 111In-HuIgG by s.c. LS-174T xenografts. Minimal uptake of i.v. injected 111In-trastuzumab in normal organs was confirmed in non-tumor-bearing mice. The in vivo behavior of 111In-trastuzumab in mice bearing intraperitoneal (i.p.) LS-174T tumors resulted in a tumor %ID/g of 130.85 ± 273.34 at 24 h. Visualization of tumor, s.c. and i.p. xenografts, was achieved by γ-scintigraphy and PET imaging. Blood pool was evident as expected, but cleared over time. The blood pharmacokinetics of i.v. and i.p. injected 111In-trastuzumab was determined in mice with and without tumors. The data from these in vitro and in vivo studies supported advancement of radiolabeled trastuzumab into two clinical studies, a Phase 0 imaging study in the Molecular Imaging Program of the National Cancer Institute and a Phase 1 radioimmunotherapy study at the University of Alabama.
authors: Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA. dm71q@nih.gov
authors: Diane E
authors: DE
authors: Milenic
authors: Karen J
authors: KJ
authors: Wong
authors: Kwamena E
authors: KE
authors: Baidoo
authors: Tapan K
authors: TK
authors: Nayak
authors: Celeste A S
authors: CA
authors: Regino
authors: Kayhan
authors: K
authors: Garmestani
authors: Martin W
authors: MW
authors: Brechbiel
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology / Q000493:pharmacokinetics*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000737:chemistry / Q000276:immunology / Q000493:pharmacokinetics; D045744:Cell Line, Tumor; D002986:Clinical Trials as Topic; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D005260:Female; D019073:HT29 Cells; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000276:immunology / Q000493:pharmacokinetics*; D007205:Indium Radioisotopes / Q000008:administration & dosage / Q000493:pharmacokinetics; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D017879:Isothiocyanates / Q000737:chemistry / Q000493:pharmacokinetics; D008297:Male; D008545:Melanoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D004369:Pentetic Acid / Q000031:analogs & derivatives / Q000737:chemistry / Q000493:pharmacokinetics; D049268:Positron-Emission Tomography; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D011877:Radionuclide Imaging; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000276:immunology; D014018:Tissue Distribution; D000068878:Trastuzumab; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D018796:Immunoconjugates; D007205:Indium Radioisotopes; D017879:Isothiocyanates; D004369:Pentetic Acid; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C085678:N-(2-amino-3-(4-isothiocyanatophenyl)propyl)cyclohexane-1,2-diamine-N,N',N',N'',N''-pentaacetic acid