Optimal Conditioning Regimen for Autologous Transplantation of Relapsing Remitting Multiple Sclerosis

This study is designed to compare two non-myeloablative conditioning regimens (combination of chemotherapy and immune specific proteins against immune cells) for relapsing remitting multiple sclerosis (RRMS). The two conditioning regimens are the most commonly used world wide in clinical practice for the treatment of multiple sclerosis (MS). The first investigational conditioning regimen is cyclophosphamide (chemotherapy) and rATG (rabbit anti-thymocyte globulin, a protein against immune cells). The second investigational conditioning regimen includes the same dose of cyclophosphamide (chemotherapy) and rituximab (a protein against immune cells). Both cyclophosphamide and either rATG or rituximab are given to kill immune cells that are thought to be causing MS, followed by return of one's own previously collected blood stem cells (autologous stem cell transplant) to hasten recovery. The goal of this study is to assess the difference of these treatments in terms of toxicity and efficacy.