Role of High-Dose Chemotherapy with Autologous Stem Cell Transplantation in Primary Systemic Amyloidosis: A Systematic Review and Meta-Analysis.

Background: Primary systemic amyloidosis (AL) is a rare plasma cell clonal disorder(8/million) characterized by extracellular deposits of material composed mainly of fragments of light chain immunoglobulin throughout a body. Standard chemotherapy (e.g. melphalan and prednisone) is associated with poor outcomes (typical median survival is between 12–18 months with less than 5% survive 10 years). Autologous stem cell transplant (ASCT) has been increasingly advocated for treatment of AL. However, it is uncertain whether ASCT is better than standard chemotherapy. To address this uncertainty, we undertook a systematic review/meta-analysis to evaluate the efficacy of high-dose chemotherapy and autologous stem-cell transplant (HSCT) versus conventional chemotherapy in patients with AL.

Methods: Data search of published studies included Medline [all randomized controlled trials (RCTs)], Cochrane library and hand search of references. Studies were included if they were comparison trials of HSCT versus conventional chemotherapy, regardless if they were RCTs, prospective studies with historical control, or single arm studies. The studies were eligible if patients had biopsy proven AL with at least one major organ involved. Data were extracted on benefits as well as harms (overall survival, event-free survival, response, treatment related mortality, treatment-related morbidity).

Results: Out of 34 identified studies only 13 met the inclusion criteria for the current systematic review (2 RCTs, 2 prospective non-randomized trials involving historical control, and 9 single arm trials). Altogether these trials enrolled 1056 patients. Pooled data from 4 trials with controls (RCT and non-RCT) found similar overall survival for ASCT and conventional therapy arms [hazard ratio (HR) of 1.10 (95% CI 0.88, 1.36, p=0.4); p= 0.6]. Analysis of data according to trial design also did not find any difference in survival [HR for RCTs was 1.10 (95% CI 0.88, 1.37) and for non RCTs HR was 0.98 (95% CI 0.29, 3.35)]. The complete hematological response was also similar in both arms in RCTs (Odds ratio [OR]=1.38, 95%CI 0.67, 2.85; p=0.4) and non RCTs (OR=1.78, 95%CI 0.22, 14.65; p=0.32). The pooled proportion of treatment-related deaths in the single arm studies for AHCT was 0.119 (95% CI = 0.09 to 0.14)].

Conclusion: The results from the meta-analysis indicate that there is no statistically significant difference between the treatment effects from high-dose chemotherapy with ASCT and conventional chemotherapy. Hence, the efficacy of ASCT in improving overall survival and complete hematological response remains to be proven.