Beneficial effects of cellular immunotherapy in the prevention and treatment of posttransplant hematologic relapse of myelodysplastic neoplasms

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative option for myelodysplastic syndrome (MDS). However, relapse remains the primary cause of transplantation failure. This single-center study aimed to evaluate factors influencing therapeutic interventions to prevent overt relapse of MDS and to identify treatment approaches that ensure optimal response and safety. We enrolled 149 patients with relapsed MDS who had undergone allo-HSCT between May 2009 and December 2017, among whom 87 patients had hematologic relapse (HemRel; marrow blasts ≥ 5%, blasts in peripheral blood or dysplasia fulfilling MDS diagnostic criteria) and 62 patients had pre-HemRel; pre-HemRel included imminent (n = 28; donor chimerism ≤ 95%), WT1-based molecular (n = 17; WT1 transcript > 250 copies/10⁴ABL1), and cytogenetic (n = 17; recurrence of chromosomal aberrations) relapses. The estimated 4-year overall survival (OS) rate from the time of relapse was 44.1% among 62 pre-HemRel patients. However, the OS rate was significantly lower in 87 HemRel patients. In a multivariate analysis, preemptive use of cellular immunotherapy (cIMTx, either donor lymphocyte infusion, second allo-HSCT, or both) emerged as an independent factor in preventing HemRel and was more effective, particularly in the presence of other unfavorable factors, such as the absence of chronic graft-versus-host disease and a higher-risk group based on the MDS-transplantation prognostic scoring system. In HemRel, using cIMTx demonstrated a significantly superior OS rate compared to non-cIMTx modalities (25.8% vs. 6.1% vs. 0%, P <.001). In summary, cIMTx demonstrated superior outcomes in both pre-HemRel and HemRel groups, proving particularly advantageous in pre-HemRel cases with progression risk factors, while its benefits remained consistent in HemRel cases.