Clinical efficacy of high-dose dexamethasone with maintenance dexamethasone/alpha interferon in patients with primary systemic amyloidosis: results of United States Intergroup Trial Southwest Oncology Group (SWOG) S9628.
Current therapy of primary systemic (AL) amyloidosis with oral melphalan and prednisone remains unsatisfactory, with a median survival of only 13 months. Between 1996 and 2003, 93 patients with biopsy-proven AL amyloidosis were enrolled in a prospective US national cooperative group trial. Treatment schema consisted of induction therapy with pulse dexamethasone (DEX), followed by maintenance therapy with DEX and alpha interferon. Hematologic complete remissions were observed in 24% and improvement in AL amyloidosis-related organ dysfunction occurred in 45% of patients evaluable for response. Median survival of the entire cohort is 31 months, with an estimated 2-year overall survival (OS) and event-free survival (EFS) of 60% and 52%, respectively. Presence of congestive heart failure and increased level of serum beta2 microglobulin (>/= 0.0035 g/L [3.5 mg/L]) were dominant predictors of adverse outcome. Estimated 2-year OS in patients who are eligible to receive transplants with this approach was 78%. These data demonstrate for the first time in the context of a US multicenter prospective clinical trial that front-line therapy with a DEX-based regimen in AL amyloidosis can lead to durable reversal of AL amyloidosis-related organ dysfunction and prolonged survival.