Risk factors, treatments and outcomes of patients with light chain amyloidosis who relapse after autologous stem cell transplantation.

Relapse after ASCT is an important factor affecting the long-term prognosis of patients with AL amyloidosis. However, the risk factors of relapse are unknown and there are limited studies on treatment outcomes of these patients. We retrospectively reviewed 170 patients with AL amyloidosis who underwent ASCT between 2010 and 2021. Seventy-six patients confirmed as relapse and the median time from ASCT to relapse was 39 months. On multivariate analysis of variables before and after ASCT, lambda restricted, dFLC >30 mg/L pre ASCT, reduced dose melphalan and dFLC >10 mg/L at 6 months after ASCT were independent risk factors for relapse, and achieving CR after induction therapy and renal response after ASCT were protective factors. Most relapsed patients were treated with bortezomib-based regimens (50%) followed by daratumumab-based regimens (22.2%) and other chemotherapy regimens (13.9%). The overall hematological response in evaluable patients was 68.2% with 56.8% achieving CR/VGPR. The median PFS and OS from post-transplant relapse were 25 months and 81 months, respectively. Patients receiving bortezomib or daratumumab showed a better survival compared to other chemotherapy regimens. In conclusion, this study identified independent risk factors of post-transplant relapse and demonstrated the superiority of bortezomib or daratumumab treatment for these patients. CLINICAL TRIAL REGISTRATION: NCT04210791.