Pulsed Low Dose Intravenous Melphalan in Patients with AL Amyloidosis, Ineligible for Aggressive Treatment with High-Dose Melphalan and Stem Cell Transplantation.

AL amyloidosis is caused by a clonal plasma cell dyscrasia and characterized by widespread, progressive deposition of Amyloid fibrils derived from monoclonal Ig light chains, leading to multisystem organ failure and death. Aggressive treatment of AL amyloidosis with high-dose melphalan followed by autologous stem cell transplant (HDM/SCT) can induce hematologic and clinical remissions and extend survival. However, not all patients are able to tolerate HDM/SCT, particularly those with severe multisystem disease. Consequently, we investigated an alternative treatment regimen consisting of pulsed low-dose intravenous melphalan (LDM) for a series of patients considered ineligible for HDM/SCT because of severe cardiac involvement and poor performance status. LDM was administered at 17.5–25 mg/m² every 4–6 weeks for 3–4 cycles depending upon patients’ clinical condition, renal function and performance status. Growth factor support was used with each cycle, and the dose of melphalan was reduced by 20% for white blood cell counts <500/mm³ and/or platelet count <20,000/mm³ during any treatment cycle. Changes in serum free light chain (FLC) levels, as well as toxicity and survival were evaluated. Fifteen patients with AL amyloidosis (11 males, 4 females; median age 55, range 47–69) were treated with this regimen between July 2002 and January 2004. Light chain isotypes were l in 11 cases and k in 4. All patients had clinically significant cardiac involvement with NYHA class III/IV congestive heart failure and/or left ventricular ejection fraction ≤ 45%, and/or ≥ 2 organ systems involved. The median number of LDM cycles given was 3 (maximum; 4), and 3 patients received only 1 cycle. Serum FLC levels were available before and after treatment in 10 patients. Eight of these patients (80%) achieved a > 50% reduction in FLC levels, and 2 (20%) achieved normal FLC levels. One patient achieved a 20–25% reduction in the FLC, and 3 experienced no reduction. Of the15 patients treated, 2 patients survive 6 and 24 months after treatment, while 13 have died (median survival, 2 months; range, 0–10 months). Ten patients (67%) died within 35 days of initiating treatment. Transient myelosuppression was the major treatment-related toxicity with neutrophil and platelet nadirs occurring 12–16 days after melphalan infusions. There was 1 death from sepsis during treatment-induced myelosuppression. In summary, pulsed low-dose intravenous melphalan (LDM) was found to induce hematologic responses in most patients who could be evaluated. However, extended survival ≥ 2 years was observed in only 1 of the 15 patients with severe amyloidosis who were studied. Nonetheless, this regimen may benefit healthier patients, particularly those with less severe cardiac involvement, who are otherwise ineligible or unable to receive HDM/SCT.