title: New synthesis of phenyl-isothiocyanate C-functionalised cyclams. Bioconjugation and (64)Cu phenotypic PET imaging studies of multiple myeloma with the te2a derivative.
abstract: Azamacrocyclic bifunctional chelating agents (BCAs) are essential for the development of radiopharmaceuticals in nuclear medicine and we wish to prove that their bioconjugation by a function present on a carbon atom of the macrocyclic skeleton is a solution of choice to maintain their in vivo inertness. Based on our very recent methodology using a bisaminal template and selective N-alkylation approach, a new synthesis of conjugable C-functionalised teta, te2a and cb-te2a has been developed. These chelators have indeed a growing interest in nuclear medicine for positron emission tomography (PET) and radioimmunotherapy (RIT) where they show in several cases better complexation properties than dota or dota-like macrocycles, especially with (64)Cu or (67)Cu radioisotopes. Chelators are bearing an isothiocyanate grafting function introduced by C-alkylation to avoid as much as possible a critical decrease of their chelating properties. The synthesis is very efficient and yields the targeted ligands, teta-Ph-NCS, te2a-Ph-NCS and cb-te2a-Ph-NCS without fastidious work-up and could be easily extended to other cyclam based-BCAs. The newly synthetised te2a-Ph-NCS has been conjugated to an anti mCD138 monoclonal antibody (mAb) to evaluate its in vivo behavior and potentiality as BCA and to explore a first attempt of PET-phenotypic imaging in multiple myeloma (MM). Mass spectrometry analysis of the immunoconjugate showed that up to 4 chelates were conjugated per 9E7.4 mAb. The radiolabeling yield and specific activity post-purification of the bioconjugate 9E7.4-CSN-Ph-te2a were 95 ± 2.8% and 188 ± 27 MBq mg(-1) respectively and the immunoreactivity of (64)Cu-9E7.4-CSN-Ph-te2a was 81 ± 7%. Animal experiments were carried out on 5T33-Luc(+) tumor bearing mice, either in subcutaneous or orthotopic. To achieve PET imaging, mice were injected with (64)Cu-9E7.4-CNS-Ph-te2a and acquisitions were conducted 2 and 20 h post-injection (PI). A millimetric bone uptake was localised in a sacroiliac of a MM orthotopic tumor. Nonspecific uptakes were observed at 2 h PI but, unlike for the tumor, a significant decrease was observed at 20 h PI which improves the contrast of the images.
authors.affiliation: Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences et Techniques, 6 Avenue Victor le Gorgeu, C.S. 93837, 29238 Brest, France. raphael.tripier@univ-brest.fr.
authors.forename: Zakaria
authors.initials: Z
authors.lastname: Halime
authors.affiliation: Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences et Techniques, 6 Avenue Victor le Gorgeu, C.S. 93837, 29238 Brest, France. raphael.tripier@univ-brest.fr and Centre de Recherche en Cancérologie Nantes-Angers (CRCNA), Unité INSERM 892 - CNRS 6299, 8 quai Moncousu, BP 70721 44007 Nantes Cedex, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Frindel
authors.affiliation: Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences et Techniques, 6 Avenue Victor le Gorgeu, C.S. 93837, 29238 Brest, France. raphael.tripier@univ-brest.fr.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Camus
authors.affiliation: Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences et Techniques, 6 Avenue Victor le Gorgeu, C.S. 93837, 29238 Brest, France. raphael.tripier@univ-brest.fr.
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Orain
authors.affiliation: Institut de Cancérologie de l'Ouest, 44800 Saint-Herblain, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Lacombe
authors.affiliation: Centre de Recherche en Cancérologie Nantes-Angers (CRCNA), Unité INSERM 892 - CNRS 6299, 8 quai Moncousu, BP 70721 44007 Nantes Cedex, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Bernardeau
authors.affiliation: Institut de Cancérologie de l'Ouest, 44800 Saint-Herblain, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Chérel
authors.affiliation: Institut de Cancérologie de l'Ouest, 44800 Saint-Herblain, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Gestin
authors.affiliation: Institut de Cancérologie de l'Ouest, 44800 Saint-Herblain, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Faivre-Chauvet
authors.affiliation: Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences et Techniques, 6 Avenue Victor le Gorgeu, C.S. 93837, 29238 Brest, France. raphael.tripier@univ-brest.fr.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Tripier
mesh_terms: D000818:Animals; D001555:Benzene Derivatives / Q000138:chemical synthesis / Q000737:chemistry*; D002614:Chelating Agents / Q000138:chemical synthesis / Q000737:chemistry*; D003301:Copper Radioisotopes / Q000737:chemistry*; D005260:Female; D017879:Isothiocyanates / Q000138:chemical synthesis / Q000737:chemistry*; D047029:Lactams, Macrocyclic / Q000138:chemical synthesis / Q000737:chemistry*; D008810:Mice, Inbred C57BL; D009101:Multiple Myeloma / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D001555:Benzene Derivatives; D002614:Chelating Agents; D003301:Copper Radioisotopes; D017879:Isothiocyanates; D047029:Lactams, Macrocyclic; D019275:Radiopharmaceuticals; C037152:isothiocyanic acid