Efficacy of autologous and allogeneic hematopoietic cell transplantation in adults with acute promyelocytic leukemia: results of a systematic review and meta-analysis

Despite therapeutic advances in acute promyelocytic leukemia (APL) with emergence of all-trans retinoic acid, arsenic trioxide and gemtuzumab-ozogamycin, approximately 10% of patients still experience disease relapse, typically occurring within 24 to 36 months following completion of front-line treatment. Traditionally, both allogeneic (allo) and autologous (auto) hematopoietic cell transplantation (HCT) have been considered reasonable treatment options in relapsed APL. However, no randomized controlled studies have been conducted comparing allo-HCT vs. auto-HCT in relapsed APL. We performed a systematic review/meta-analysis (SR/MA) to assess the totality of evidence pertaining to allo-HCT or auto-HCT in relapsed APL. Our search identified 1,158 references, of which 23 met our inclusion criteria. While acknowledging limitations of comparing, indirectly, these two treatment modalities, based on results from separate MA, it appears that pooled rates of event-free (71% vs. 54%), progression-free (63% vs. 43%), and overall (82% vs. 58%) survival are higher when an auto-HCT was prescribed. This difference could be explained, in part, due to the higher risk of pooled non-relapsed mortality rate when patients receive an allo-HCT (29% vs. 5%), owing to inherent risks associated with this modality. In the absence of a randomized prospective clinical trial comparing allo-HCT vs. auto-HCT, results show that both modalities are acceptable in relapsed APL. The higher pooled non-relapsed mortality rate with allo-HCT is an important consideration when choosing this option. Additionally, the comparable pooled relapse rate (24% vs. 23%), for auto-HCT vs. allo-HCT, respectively, provides rationale to evaluate post-HCT consolidative strategies to mitigate this risk.