Risk Adapted Intravenous Melphalan and Adjuvant Thalidomide and Dexamethasone for Untreated Patients With Primary Systemic Amyloidosis

OBJECTIVES: Primary * Determine the 2-year and overall progression-free survival of patients with newly diagnosed, previously untreated primary systemic (AL) amyloidosis treated with risk-adapted melphalan followed by thalidomide and dexamethasone. Secondary * Determine plasma cell disease response in these patients at 3, 12, and 24 months after treatment with this regimen. * Determine amyloid-related disease response in these patients at 12 and 24 months after treatment with this regimen. * Determine the prognostic significance of immunoglobulin light-chain variable-region germline gene expression by AL plasma cell clones in patients treated with this regimen. * Determine whether there is molecular minimal residual disease at 12 and 24 months in patients achieving a complete hematologic response after treatment with this regimen. OUTLINE: Patients are stratified according to the extent of amyloid-related disease (low-risk vs high-risk). * High-risk disease: Patients receive 2 courses of low-dose melphalan IV, dexamethasone, and filgrastim (G-CSF). After 3 months, patients receive thalidomide and dexamethasone if plasma cell disease persists. * Low-risk disease: Patients receive 1 course of high-dose melphalan IV and G-CSF. Patients then receive thalidomide and dexamethasone as in high-risk disease regimen. Patients are followed at 3, 12, and 24 months. PROJECTED ACCRUAL: A total of 82 patients will be accrued for this study.