Bortezomib and Dexamethasone Followed by High-Dose Melphalan and Stem Cell Transplantation for Primary (AL) Amyloidosis

The drugs dexamethasone and bortezomib are both FDA-approved for the treatment of multiple myeloma, a disease very similar to amyloidosis. However, they are currently investigational for the treatment of amyloidosis. We want to find out if the addition of dexamethasone and bortezomib to standard high dose chemotherapy and stem cell transplant can help improve response. Standard treatment includes four steps: 1) Stem Cell Mobilization (standard) 2) Stem Cell Collection (standard) 3) Conditioning Regimen (Melphalan chemotherapy). The conditioning regimen helps to kill the abnormal cells in the body and makes room in the bone marrow for new blood stem cells to grow. 4) Stem Cell Infusion Participants in this study will have an additional treatment step called "induction therapy", designed as the first step towards reducing the number of abnormal cells in the body. Two cycles of the investigational drugs bortezomib and dexamethasone will be given during induction therapy. In addition, bortezomib will given as part of the conditioning regimen, in addition to the standard melphalan chemotherapy.