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 for acute promyelocytic leukemia (APL) with the 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 for relapsed APL; however, no randomized controlled studies have been conducted comparing allo-HCT and auto-HCT in patients with relapsed APL. We performed a systematic review/meta-analysis to assess the totality of evidence pertaining to allo-HCT or auto-HCT in relapsed APL. Our search identified 1158 references, of which 23 met our inclusion criteria. While acknowledging the limitations of comparing these 2 treatment modalities indirectly, based on results from separate meta-analyses, it appears that pooled rates of event-free survival (71% versus 54%), progression-free survival (63% versus 43%), and overall survival (82% versus 58%) are higher after auto-HCT. This difference can be explained in part by the higher risk of pooled nonrelapse mortality (NRM) in patients undergoing allo-HCT (29% versus 5%), owing to inherent risks associated with this modality. In the absence of a randomized prospective clinical trial comparing allo-HCT and auto-HCT, our results show that both modalities are acceptable in patients with relapsed APL. The higher pooled NRM rate with allo-HCT is an important consideration when choosing this option. Additionally, the comparable pooled relapse rate for auto-HCT and allo-HCT (24% versus 23%) provides a rationale for evaluating post-HCT consolidative strategies to mitigate this risk.