title: Novel Tumor Pretargeting System Based on Complementary l-Configured Oligonucleotides.
abstract: Unnatural mirror image l-configured oligonucleotides (L-ONs) are a convenient substance class for the application as complementary in vivo recognition system between a tumor specific antibody and a smaller radiolabeled effector molecule in pretargeting approaches. The high hybridization velocity and defined melting conditions are excellent preconditions of the L-ON based methodology. Their high metabolic stability and negligible unspecific binding to endogenous targets are superior characteristics in comparison to their d-configured analogs. In this study, a radiopharmacological evaluation of a new l-ONs based pretargeting system using the epidermal growth factor receptor (EGFR) specific antibody cetuximab (C225) as target-seeking component is presented. An optimized PEGylated 17mer-L-DNA was conjugated with p-SCN-Bn-NOTA (NOTA') to permit radiolabeling with the radionuclide64Cu. C225 was modified with the complementary 17mer-L-DNA (c-L-DNA) strand as well as with NOTA' for radiolabeling and use for positron emission tomography (PET). Two C225 conjugates were coupled with 1.5 and 5.0 c-L-DNA molecules, respectively. In vitro characterization was done with respect to hybridization studies, competition and saturation binding assays in EGFR expressing squamous cell carcinoma cell lines A431 and FaDu. The modified C225 derivatives exhibited high binding affinities in the low nanomolar range to the EGFR. PET and biodistribution experiments on FaDu tumor bearing mice with directly64Cu-labeled NOTA'3-C225-(c-L-DNA)1.5conjugate revealed that a pretargeting interval of 24 h might be a good compromise between tumor accumulation, internalization, blood background, and liver uptake of the antibody. Despite internalization of the antibody in vivo pretargeting experiments showed an adequate hybridization of64Cu-radiolabeled NOTA'-L-DNA to the tumor located antibody and a good tumor-to-muscle ratio of about 11 resulting in a clearly visible image of the tumor after 24 h up to 72 h. Furthermore, low accumulation of radioactivity in organs responsible for metabolism and excretion was determined. The presented results indicate a high potential of complementary L-ONs for the pretargeting approach which can also be applied to therapeutic radionuclides such as177Lu,90Y,186Re, or188Re.
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Maik
authors.initials: M
authors.lastname: Schubert
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Bergmann
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Förster
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Wiebke
authors.identifier: 0000-0002-2876-9925
authors.initials: W
authors.lastname: Sihver
authors.affiliation: NOXXON Pharma AG , 10589 Berlin, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Vonhoff
authors.affiliation: NOXXON Pharma AG , 10589 Berlin, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Klussmann
authors.affiliation: NOXXON Pharma AG , 10589 Berlin, Germany.
authors.forename: Lucas
authors.initials: L
authors.lastname: Bethge
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Walther
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Jörn
authors.initials: J
authors.lastname: Schlesinger
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.|Technische Universität Dresden , School of Science, Department of Chemistry and Food Chemistry, 01062 Dresden, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Pietzsch
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.|Technische Universität Dresden , School of Science, Department of Chemistry and Food Chemistry, 01062 Dresden, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Steinbach
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research , Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Pietzsch
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000188:drug therapy; D045744:Cell Line, Tumor; D000068818:Cetuximab / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D066246:ErbB Receptors / Q000276:immunology; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry*; D008099:Liver / Q000378:metabolism; D051379:Mice; D009841:Oligonucleotides / Q000737:chemistry*; D011868:Radioisotopes / Q000737:chemistry; D019275:Radiopharmaceuticals / Q000138:chemical synthesis* / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D018796:Immunoconjugates; D009841:Oligonucleotides; D011868:Radioisotopes; D019275:Radiopharmaceuticals; D066246:ErbB Receptors; D000068818:Cetuximab