Zinc and tetrathiomolybdate for the treatment of Wilson's disease and the potential efficacy of anticopper therapy in a wide variety of diseases

Abstract

Wilson's disease, an autosomal recessive disease of copper accumulation and copper toxicity primarily in the liver and brain, has been the engine that has driven the development of anticopper drugs. Here we first briefly review Wilson's disease, then review the four anticopper drugs used to treat Wilson's disease. We then discuss the results of therapy with anticopper drugs in Wilson's disease, with special emphasis on the newer and better drugs, zinc and tetrathiomolybdate. We then discuss new areas of anticopper therapy, lowering copper availability with tetrathiomolybdate as a therapy in fibrotic, inflammatory, and autoimmune disorders. Many of the cytokines which promote these disorders are copper dependent, and lowering copper availability lessens the activity of these cytokines, favorably influencing a variety of disease processes. Copper in the blood can be thought of as in two pools. One pool is covalently bound in ceruloplasmin, a protein containing six coppers, synthesized by the liver and secreted into the blood. Ceruloplasmin copper accounts for almost 85 to 90% of the blood copper in normal people. This copper is tightly bound and not readily available for cellular uptake and copper toxicity. The other 10-15% of copper is more loosely bound to albumin and other small molecules in the blood, and is readily and freely available to cells and available to cause copper toxicity, if this pool of copper is increased. We call this latter pool of copper "free" copper because of its more ready availability. However, it should be understood that it is not completely free, always being bound to albumin and other molecules. It is this pool of free copper that is greatly expanded in untreated Wilson's patients undergoing copper toxicity.