Treatment of Wilson disease with ammonium tetrathiomolybdate - III. Initial therapy in a total of 55 neurologically affected patients and follow-up with zinc therapy

Background: It is unclear what anticopper drug to use for patients with Wilson disease who present with neurologic manifestations because penicillamine often makes them neurologically worse and zinc is slow acting. Objective: To evaluate the frequency of neurologic worsening and drug adverse effects with ammonium tetrathiomolybdate. Design: Open-label study of 55 untreated patients (22 of them new) presenting with neurologic Wilson disease treated with tetrathiomolybdate varying from 120 to 410 mg/d for 8 weeks and then followed up for 3 years. Neurologic function was assessed with scored neurologic and speech tests. Setting: A university hospital referral setting. Patients: All untreated, newly diagnosed patients with neurologic Wilson disease. Intervention: Treatment with tetrathiomolybdate. Main Outcome Measures: Neurologic function was evaluated by neurologic and speech examinations. Drug adverse effects were evaluated by complete blood cell counts and biochemical measures. Results: Only 2 (4%) of 55 patients treated with tetrathiomolybdate showed neurologic deterioration, compared with an estimated 50% of penicillamine-treated patients. Five of the 22 new patients exhibited bone marrow suppression and 3 had aminotransferase elevations. These numbers are higher than in the original 33 patients and appear to be due primarily to a more rapid dose escalation. Conclusions: Tetrathiomolybdate shows excellent efficacy in patients with Wilson disease who present with neurologic manifestations. With rapid escalation of dose, adverse effects from bone marrow suppression or aminotransferase elevations can occur.