It is planned to recruit a total of 12 patients to the study. Patients will be randomised 1:1 to one of the two dose levels (1500 mg/kg or 2500 mg/kg; six patients per dose level). Treatment will be administered every two weeks by slow IV infusion over 8 hours at different concentrations to achieve the proscribed dose levels. Patients will receive treatment for a total of 12 weeks. Patients who withdraw prior to completion of the initial pharmacokinetic and pharmacodynamic assessments will be replaced.