Copper chelators targeted at the liver: a innovative treatment of hepatic copper overload – COPDETOX

The COPDETOX project involves multidisciplinary work, from synthetic chemistry and physico-chemical characterization to cell biology and in vivo experiments, including pharmacokinetics. The project is built around four partners from two different basic research divisions of the CEA: Partners 1 and 2 have complementary experiences, in chemistry and biology of metal chelating molecules or proteins, respectively and Partner 3 has an acknowledged expertise in quantitative mass spectrometry of molecules isolated from biological fluids or organs. Partner 4 is the CEA technology transfer office.
The project comprises four experimental work packages: (1) Design and synthesis of the liver targeted copper chelators, (2) in vitro evaluation of complexation and targeting properties, (3) in cellulo evaluation of cell entry and intracellular copper decrease and (4) in vivo evaluation in two animal models of Wilson’s disease.
Market analysis and contacts with pharmaceutical industries for licensing will be the task of the technology transfer office.

The series of chelators targeted to the liver, developed in COPDETOX allowed us to select one lead molecule with an optimum molecular architecture for copper chelation in vivo. A first proof of concept of the efficacy of this molecule has been obtained in Wilson Disease mice, without detection of any secondary effects. Therefore COPDETOX is an important advance for the design of more specific chelators to treat Wilson Disease, even though the route is still long to get a new drug: regulatory toxicity, dose-efficacy determination, formulation, proof of concept in more relevant model animals and finally clinical trials.

The COPDETOX project has allowed us to get the initial proof of concept of the efficacy of the copper chelator targeted at the liver in mice. The in vivo behaviour of the molecule has now to be studied extensively, to bring this innovative drug to the market. To do so we both have national and international contacts with all the orphan drug development players.

The first drug candidate is a copper chelator having a very high affinity, targeted at the liver cells. The proof of concept of its activity in hepatic cells was demonstrated before the start of this project and was validated by a publication in a high impact chemistry journal:
A.M. Pujol, M. Cuillel, A.-S. Jullien, C. Lebrun, D. Cassio, E. Mintz, C. Gateau, P. Delangle
A Sulfur Tripod Glycoconjugate that Releases a High-Affinity Copper Chelator in Hepatocytes
Angewandte Chemie International Edition, 2012, 51, pp 7445-7448

Other publications:
C Gateau, P Delangle
Design of intrahepatocyte copper(I) chelators as drug candidates for Wilson’s disease
Annals of the New York Academy of Sciences, 2014, 1315, pp 30-36.

C Gateau, E Mintz, P Delangle
Rational design of Cu and Fe chelators to treat Wilson’s disease and hemochromatosis.
In Ligand Design in Medicinal Inorganic Chemistry, Editor T Storr, WILEY-BLACKWELL; 2014, chapter 11, pp287-319

AS Jullien, C Gateau, C Lebrun, I Kieffer, D Testemale, P Delangle
D-Penicillamine Tripodal Derivatives as Efficient Copper(I) Chelators
Inorganic Chemistry 2014, 53, pp 5229-39

AS Jullien, C Gateau, I Kieffer, D Testemale, P Delangle
X-Ray Absorption Spectroscopy Proves the Trigonal Planar Sulfur-Only Coordination of Cu(I) with High Affinity Tripodal Pseudopeptides
Inorganic Chemistry 2013, 52, pp 9954-61.

P Delangle, E Mintz
Chelation therapy in Wilson’s disease: from D-Penicillamine to the design of selective bioinspired intracellular Cu(I) chelators
Dalton Transactions 2012, 41, pp 6359-70.

Metal overload plays an important role in several diseases such as Wilson’s disease, a major genetic disorder of copper metabolism in humans. The Wilson’s disease is a rare disease (~ 1000 cases in France, 10000 in the EU and 10000 in the USA) due to the lack of a protein responsible for the excretion of excess copper from the body. It results in an hepatic copper overload that is lethal if not diagnosed. The current treatments are poorly selective for copper and induce major side effects. It is therefore a societal issue to design innovative chelators that are (i) highly selective for copper to avoid disturbance of other essential metals like zinc and (ii) targeted at the liver, where copper is accumulated, to avoid copper chelation at other places in the body.
In our laboratory, we are developing efficient copper chelators, some of them coupled to liver-targeting units. Some of them were shown to enter hepatocytes and to lower the intracellular copper concentration; they are thus good candidates to eliminate copper from the liver. This proposal aims at optimizing in vitro and validating in vivo such efficient copper chelators as potential and innovative drugs to treat people suffering from copper overload such as Wilson’s disease patients. Two patents are already held for the chelating and therapeutic activities of the molecules from two families and we are now willing to get the proof of concept done on animal models.
A first compound will be tested soon in vivo after we get financial support from GRAVIT (http://www.gravit-innovation.org/) in April 2011. Another compound of even higher affinity for copper, will be evaluated in the present COPDETOX project. It will be given to healthy rodents to check their tolerance to the molecule and to Wilson’s disease model rodents to test its efficiency by comparison with the chelator currently prescribed. Another important step will be to optimize the chelator chemical structure and the targeting unit to get even more efficient molecules. The best candidates selected in vitro will be tested using cell culture and when appropriate in vivo, using animal models such as LEC rats or atp7b-/- mice. Toxicity studies will then be envisaged.
The outcome expected from this project is the proof that liver-targeted copper chelators are able to promote copper excretion in Wilson’s disease animal models with minimal side effects and toxicity. We should have enough data to interest some drug companies involved in the rare disease field.