Risk‐adapted autologous stem cell transplantation with adjuvant dexamethasone ± thalidomide for systemic light‐chain amyloidosis: results of a phase II trial

Summary High-dose melphalan (MEL) with autologous stem cell transplant (SCT) is an effective therapy for systemic AL amyloidosis (AL), but treatment-related mortality (TRM) has historically been high. We performed a phase II trial of risk-adapted SCT followed by adjuvant dexamethasone (dex) and thalidomide (thal) in an attempt to reduce TRM and improve response rates. Patients (n = 45) with newly diagnosed AL involving ≤2 organ systems were assigned to MEL 100, 140, or 200 mg/m2 with SCT, based on age, renal function and cardiac involvement. Patients with persistent clonal plasma cell disease 3 months post-SCT received 9 months of adjuvant thal/dex (or dex if there was a history of deep vein thrombosis or neuropathy). Organ involvement was kidney (67%), heart (24%), liver/GI (22%) and peripheral nervous system (18%), with 31% having two organs involved. TRM was 4·4%. Thirty-one patients began adjuvant therapy, with 16 (52%) completing 9 months of treatment and 13 (42%) achieving an improvement in haematological response. By intention-to-treat, overall haematological response rate was 71% (36% complete response), with 44% having organ responses. With a median follow-up of 31 months, 2-year survival was 84% (95% confidence interval: 73%, 94%). Risk-adapted SCT with adjuvant thal/dex is feasible and results in low TRM and high haematological and organ response rates in AL patients.