Autologous hematopoietic cell transplantation during second or subsequent complete remission of acute promyelocytic leukemia: a prognostic factor analysis

Autologous hematopoietic cell transplantation (HCT) is an effective therapy for patients with relapsed acute promyelocytic leukemia (APL). However, it remains unclear whether this procedure is equally effective for certain groups of patients. To address this question, we analyzed 296 patients with APL who had undergone autologous HCT during second or subsequent complete remission (CR2+) between 2006 and 2019. Among them, 24 patients were ≥65 years old, and 17 underwent autologous HCT during third or subsequent CR. Of the 286 patients whose measurable residual disease (MRD) data were available, 21 showed detectable MRD. The 5-year probabilities of relapse-free survival (RFS), overall survival, relapse, and nonrelapse mortality for the entire cohort were 85%, 88%, 9%, and 6%, respectively. The multivariate analysis revealed that the duration of first CR ( < or ≥2 years) was the sole factor associated with RFS (P = 0.002), but even those with CR1 duration <2 years showed a 5-year RFS of 76%. The other factors such as age, disease status, and MRD status were not predictive for the survival outcomes. Our findings demonstrate very favorable long-term results when autologous HCT is conducted during CR2 + across the various subgroups of patients with relapsed APL.