New AMD3100 derivatives for CXCR4 chemokine receptor targeted molecular imaging studies: synthesis, anti-HIV-1 evaluation and binding affinities

CXCR4 is a target of growing interest for the development of new therapeutic drugs and imaging agents as its role in multiple disease states has been demonstrated. AMD3100, a CXCR4 chemokine receptor antagonist that is in current clinical use as a haematopoietic stem cell mobilising drug, has been widely studied for its anti-HIV properties, potential to inhibit metastatic spread of certain cancers and, more recently, its ability to chelate radiometals for nuclear imaging. In this study, AMD3100 is functionalised on the phenyl moiety to investigate the influence of the structural modification on the anti-HIV-1 properties and receptor affinity in competition with anti-CXCR4 monoclonal antibodies and the natural ligand for CXCR4, CXCL12. The effect of complexation of nickel(II) in the cyclam cavities has been investigated. Two amino derivatives were obtained and are suitable intermediates for conjugation reactions to obtain CXCR4 molecular imaging agents. A fluorescent probe (BODIPY) and a precursor for 18F (positron emitting isotope) radiolabelling were conjugated to validate this route to new CXCR4 imaging agents

Synthèse et étude de nouveaux agents chélatants optimisés ciblant le récepteur de chimiokine CXCR4

The objective of this thesis work was to develop CXCR4-targeted tools to localize and treat cancer at an early stage. In this line, we investigated the synthesis of new target-specific radiopharmaceuticals. The work focused on two main axes, i.e. the chelating agent and the carrier, by using the know-how and the expertise of our group in polyazacycloalkanes synthesis and functionalization. In the first part, we were interested in developing new macrocyclic scaffolds of high potential for copper and gallium chelation. We first focused on the development of a new powerful route towards selectively functionalized constrained homocyclens. The second part was based on C-functionalized 1,4,7-triazacyclononane (TACN) and its derivatives. From a synthetic route previously developed in our group, we were able to facilitate and optimize the synthesis of selectively N- and C-functionalized TACN. By varying the grafting functions and the pendant coordinating arms, we prepared several really promising bifunctional chelating agents for copper and gallium chelation. We also investigated the synthesis of new cryptands based on cyclen and we studied their properties towards copper complexation. In the second part of this thesis work, we were interested in generating a new family of imaging agents based on well-known CXCR4 antagonists, i.e. AMD3100 and AMD3465. The access towards these agents first required the preparation of original building blocks by modification of the AMD3100 and AMD3465 cores. The conjugation of such platforms onto the appropriate probe enabled the synthesis of various systems for optical and nuclear imaging. Thus, we were able to introduce a bodipy dye and several chelators adapted for gallium, copper and indium chelationL’objectif de ce travail de thèse était de développer des outils pour détecter et traiter le cancer àun stade précoce. Nous avons donc entrepris la synthèse de nouveaux radiopharmaceutiques ciblantspécifiquement le récepteur CXCR4, en utilisant le savoir-faire et l'expertise de notre groupe dans lasynthèse et la fonctionnalisation des polyazacycloalcanes. Nous avons travaillé simultanément surdeux aspects : l’agent chélatant et la molécule vectrice.Dans un premier temps, les travaux ont concerné la conception, la synthèse et la caractérisationde nouveaux macrocycles à fort potentiel pour la chélation du cuivre et du gallium. Nous avons toutd’abord développé une nouvelle voie de synthèse permettant d’accéder à des dérivés homocyclènesC-functionnalisés. Nous nous sommes ensuite intéressés aux dérivés du 1,4,7-triazacyclononane(TACN). En optimisant une voie de synthèse déjà développée au laboratoire, nous avons facilitél’accès à des dérivés TACN N- et C-fonctionnalisés. Nous avons ainsi préparé une série denouveaux agents chélatants bifonctionnels adaptés pour la complexation du cuivre ou du gallium, envariant la nature de la fonction de greffage et des bras coordinants. Nous avons également réalisé lasynthèse de nouveaux cryptands en série cyclène et nous avons étudié leur propriété decomplexation vis à vis du cuivre.Dans un second temps, nous avons développé une nouvelle famille d’agents imageants duCXCR4 en modifiant la structure des AMD3100 et AMD3465. Ce travail a tout d’abord nécessité lamise au point de nouvelles méthodes de fonctionnalisation de ces structures. Nous avons ainsi pupréparer de nouveaux synthons porteur d’une fonction de greffage dans les deux séries. Nous avonsensuite introduit différentes sondes imageantes, telles que des chélates adaptés pour la complexationdu cuivre, gallium et indium ainsi que des sondes fluorescentes de type bodip

AMD3100: A Versatile Platform for CXCR4 Targeting 68 Ga-Based Radiopharmaceuticals

International audienceCXCR4 is a G protein-coupled receptor (GPCR), which is overexpressed in numerous diseases, particularly in multiple cancers. Therefore, this receptor represents a valuable target for imaging and therapeutic purposes. Among the different approaches, which were developed for CXCR4 imaging, a CXCR4 antagonist biscyclam system (AMD3100, also called Mozobil), currently used in the clinic for the mobilization of hematopoietic stem cells, was radiolabeled with different radiometals such as 62Zn, 64Cu, 67Ga, or 99mTc. However, cyclam is not an ideal chelator for most of these radiometals, and could lead to the release of the radionuclide in vivo. In the current study, a new family of CXCR4 imaging agents is presented, in which AMD3100 is used as a carrier for specific delivery of an imaging reporter, i.e., a 68Ga complex for PET imaging. AMD3100 was functionalized on the phenyl moiety with different linkers, either ethylenediamine or diamino-polyethylene glycol 3 (PEG3). The resulting AMD3100 analogues were further coupled with two different chelators, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) or 1,4,7-triazacyclononane-1-glutaric acid-4,7-acetic acid (NODAGA). Five potential CXCR4 targeting agents were obtained. The derived AMD3100-based ligands were labeled with 68Ga, highlighting the influence of the spacer nature on the 68Ga-labeling yield. The lipophilic character of the different systems was also investigated, as well as their affinity for the CXCR4 receptor. The most promising compound was further evaluated in vivo in H69 tumor xenografts by biodistribution and PET imaging studies, validating the proof of principle of our concept

Efficient Synthesis of Multifunctional Chelating Agents Based on Tetraazacycloalkanes

International audienceAn efficient route has been developed for the synthesis of multifunctional tetraazacycloalkanes (in particular 1,4,7,10-tetraazacyclotridecane) incorporating an aminomethyl pendant arm on the carbon skeleton. Starting from the appropriate C-functionalized bisaminal-protected intermediate, the target macrocycles were easily obtained by means of a step-by-step introduction of the desired functional groups onto the free primary amine group, followed by deprotection of the bisaminal intermediates. This straightforward and versatile synthetic approach paves the way for the design of a new family of multifunctional chelators

Bone marrow endothelial dysfunction promotes myeloid cell expansion in cardiovascular disease

Abnormal hematopoiesis advances cardiovascular disease by generating excess inflammatory leukocytes that attack the arteries and the heart. The bone marrow niche regulates hematopoietic stem cell proliferation and hence the systemic leukocyte pool, but whether cardiovascular disease affects the hematopoietic organ's microvasculature is unknown. Here we show that hypertension, atherosclerosis and myocardial infarction (MI) instigate endothelial dysfunction, leakage, vascular fibrosis and angiogenesis in the bone marrow, altogether leading to overproduction of inflammatory myeloid cells and systemic leukocytosis. Limiting angiogenesis with endothelial deletion of Vegfr2 (encoding vascular endothelial growth factor (VEGF) receptor 2) curbed emergency hematopoiesis after MI. We noted that bone marrow endothelial cells assumed inflammatory transcriptional phenotypes in all examined stages of cardiovascular disease. Endothelial deletion of Il6 or Vcan (encoding versican), genes shown to be highly expressed in mice with atherosclerosis or MI, reduced hematopoiesis and systemic myeloid cell numbers in these conditions. Our findings establish that cardiovascular disease remodels the vascular bone marrow niche, stimulating hematopoiesis and production of inflammatory leukocytes

Bone marrow endothelial dysfunction promotes myeloid cell expansion in cardiovascular disease

Abnormal hematopoiesis advances cardiovascular disease by generating excess inflammatory leukocytes that attack the arteries and the heart. The bone marrow niche regulates hematopoietic stem cell proliferation and hence the systemic leukocyte pool, but whether cardiovascular disease affects the hematopoietic organ's microvasculature is unknown. Here we show that hypertension, atherosclerosis and myocardial infarction (MI) instigate endothelial dysfunction, leakage, vascular fibrosis and angiogenesis in the bone marrow, altogether leading to overproduction of inflammatory myeloid cells and systemic leukocytosis. Limiting angiogenesis with endothelial deletion of Vegfr2 (encoding vascular endothelial growth factor (VEGF) receptor 2) curbed emergency hematopoiesis after MI. We noted that bone marrow endothelial cells assumed inflammatory transcriptional phenotypes in all examined stages of cardiovascular disease. Endothelial deletion of Il6 or Vcan (encoding versican), genes shown to be highly expressed in mice with atherosclerosis or MI, reduced hematopoiesis and systemic myeloid cell numbers in these conditions. Our findings establish that cardiovascular disease remodels the vascular bone marrow niche, stimulating hematopoiesis and production of inflammatory leukocytes