Novel approaches to the treatment of primary amyloidosis.

Primary (AL, amyloid light-chain) amyloidosis is a plasma cell disorder in which deposits of amyloid light-chain protein cause progressive organ failure. It is important to recognise that amyloidosis is a dynamic process and chemotherapy-induced reduction of the activity of the plasma cell clone reduces the supply of the amyloid precursor protein and can result in a major regression of the deposits. The most common target organ is the kidney and renal amyloidosis manifests as proteinuria or nephrotic syndrome. Proteinuria is seen in three quarters of patients. Amyloid related nephrotic syndrome and renal failure are potentially reversible. Fatigue, congestive heart failure, hepatomegaly, peripheral neuropathy, orthostatic hypotension, carpal tunnel syndrome and macroglossia are other common features. The median survival is one to two years. Conventional-dose melphalan as standard treatment can prolong the median duration of survival by about ten months, but the clinical response rates with improvement of impaired organ function are low. Up-front high-dose chemotherapy with autologous peripheral blood stem cell transplantation is much more effective and can result in a major improvement in the clinical condition of patients. However, the toxicity related to this treatment can be relevant due to impaired organ function. Conventional-dose chemotherapy consisting of vincristine, doxorubicin and dexamethasone or high-dose dexamethasone or interferon-alpha are other possible approaches to treatment. The improvement of patient condition with an effective conventional-dose chemotherapy may increase the tolerability of high-dose chemotherapy and reduce transplantation related problems.