Impact of chimaerism analysis and kinetics on allogeneic haematopoietic stem cell transplantation outcome after conventional and reduced‐intensity conditioning regimens

Abstract

This retrospective study aimed to analyse the impact on overall survival (OS) and event-free survival (EFS) of chimaerism status and kinetics following allogeneic conventional and reduced-intensity conditioning haematopoietic stem cell transplantation, and to compare this with the impact of other well-known factors. We investigated the chimaerism status of 187 patients [84 females, 103 males; median age 39.5 years (range, 17-62 years)]. After transplantation, 121 patients (65%) presented full donor chimaerism (FDC) and 63 (34%) mixed chimaerism (MC). For MC, we divided the population into patients who presented regressive mixed chimaerism (RMC) (21 patients: 11%), stable mixed chimaerism (SMC) (20 patients: 11%) and progressive mixed chimaerism (PMC) (22 patients: 12%). At last follow-up, 71 patients were alive and 116 had died (48% from disease progression and 52% from transplant-related causes). With a mean follow-up of 39.4 and 34.8 months, the 5-year probabilities of OS and EFS for the total group were, respectively, 55% and 43%: 69.5% and 61% for FDC, 35.4% and 25% for RMC, 42.6% and 28.6% for SMC, and 21% and 10.4% for PMC (P < 0.0001 and P < 0.0001). Multivariate analysis only showed a significant impact of chimaerism status on OS, as well as acute and chronic graft-versus-host disease on EFS, with a trend for conditioning regimen.