Safety evaluations will be performed at specified intervals throughout the study and will consist of laboratory tests, vital signs (such as blood pressure), physical examinations and the occurrence and severity of adverse events as well as other study specific procedures. Patients will receive infusions of either 5mg/kg, 10 mg/kg or placebo at weeks 0, 2, 6, and then once every 8 weeks thereafter through week 46 for up to 3 years.