Tetrathiomolybdate, a copper chelator for the treatment of Wilson disease, pulmonary fibrosis and other indications

Tetrathiomolybdate (TTM) is a copper chelator that has also demonstrated antiangiogenic, antifibrogenic and anti-inflammatory actions in preclinical studies. The drug, from the University of Michigan was licensed to Pipex Pharmaceuticals Inc for development for several indications; development of the drug for cancer was later licensed to Attenuon LLC. In a phase III clinical trial, TTM stabilized neurological function in patients with Wilson disease, causing significant recovery in 81% of patients at 3 years post initiation of therapy; a second phase III trial was ongoing at the time of publication. A phase I/II clinical trial demonstrated the efficacy of TTM in patients with idiopathic pulmonary fibrosis, and led the FDA to grant TTM Orphan Drug status for this disease. Several phase II clinical trials had also been completed in patients with various cancers, and revealed mixed efficacy. TTM was also assessed in a phase I clinical trial for age-related macular degeneration, but the results reported from the trial were negative; no further development has occurred for this indication. TTM was assessed for the treatment of psoriasis in a phase II clinical trial, but no data have been reported. At the time of publication, phase II and phase III clinical trials were ongoing in patients with Alzheimer's disease and primary biliary cirrhosis, respectively. The most common clinical side effects observed for TTM over the range of indications have been anemia, neutropenia, leukopenia and transanimase elevations. These side effects were generally resolved with either a dose adjustment or temporary suspension of the dosing regimen. TTM is predicted to most likely find a niche in the therapy of Wilson disease, for which current treatment options are limited.