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.
RATIONALE: Drugs such as melphalan, thalidomide, and dexamethasone may be effective in treating patients with primary systemic amyloidosis.~PURPOSE: This phase II trial is studying how well giving melphalan together with thalidomide and dexamethasone works in treating patients with primary systemic amyloidosis.