Melphalan and Dexamethasone With or Without Bortezomib in Treating Patients With Previously Untreated Systemic Light-Chain Amyloidosis

Inclusion Criteria: * Histologically confirmed diagnosis of systemic light-chain amyloidosis * Histologic diagnosis of disease must be confirmed by pathology (positive Congo red stain with green birefringence on polarized light microscopy) * Genetic testing must be negative for transthyretin mutations associated with hereditary amyloidosis (required in patients who are African-American or who present with peripheral neuropathy as the dominant organ involvement) * Measurable disease, defined by \>= 1 of the following: * Serum M-protein \>= 1 g/dL by serum protein electrophoresis (SPEP) * Difference between involved and uninvolved free light chain be \>4.0mg/dL provided the kappa to lambda free light chain (FLC) ratio is abnormal * Symptomatic organ involvement\* (heart, kidney, liver/gastrointestinal tract, peripheral nervous system, or soft tissue), defined as any of the following: * NOTE: \*Carpal tunnel syndrome skin purpura or the presence of vascular amyloid on a bone marrow biopsy alone are not sufficient to meet criteria for "symptomatic organ involvement" * Renal involvement is defined as proteinuria (predominantly albumin) \> 0.5 g/day by 24-hour urine collection * Cardiac involvement is defined as the presence of a mean left ventricular wall thickness of \> 12 mm by echocardiogram in the absence of a history of hypertension or valvular heart disease or in the presence of unexplained low voltage (\< 0.5 mV) by electrocardiogram * Hepatic involvemen…