The monogenetic disease Wilson's disease is caused by a defect in the transmembrane copper transport pump ATP7B. In healthy people, this pump causes, among other things, the removal of excess copper via the bile. If copper is not transported away efficiently, copper deposits form in various tissues, which are then chronically damaged. The liver is initially affected in many patients, but neuropsychiatric symptoms are also common; mixed forms are also known. The recognized therapy for excreting excess copper using chelators such as D-penicillamine (metalcaptase) or triethylenetetramine (trientine, TETA) is effective, but is not tolerated by all patients.

Recently, data from a phase 2 study with a new oral drug based on the copper-binding agent tetrathiomolybdate (TTM) for the treatment of patients with Wilson's disease were published in a subsidiary journal of the Lancet (Weiss et al., 2017). The mechanism of action of the so-called WTX101 (bischoline tetrathiomolybdate) differs from the therapies already mentioned above all in that excess copper is transported away via the bile rather than via the kidneys. This uses the physiological route of copper, which can have a positive effect on the tolerability and effectiveness of WTX101.

Patients are currently being recruited in the USA and at some European sites for a subsequent phase III study. In this study phase, the potential new drug is given to a larger cohort of patients and its effectiveness and tolerability are checked. This is a so-called approval study. In the US, WTX101 has been included in the fast track process FDA, which is designed to enable rapid testing and approval of promising new drugs for serious diseases.