This study aimed to evaluate the efficacy of reduced intensity conditioning (RIC) regimen in elderly or high comorbidity burden patients who receive haploidentical hematopoietic stem cell transplantation (haplo-HSCT). Haplo-HSCT is an effective treatment option for patients who did not have identical sibling donor (ISD) or unrelated donor (URD). However, post-transplant transplant-related mortality (TRM) is one of the major causes for transplant failure, and the risk of TRM for old patients or those with high comorbidity burden was higher. RIC regimen may decrease the risk of TRM for haplo-HSCT recipients. The study hypothesis: Using RIC haplo-HSCT regimen in elderly patients or those with high comorbidity burden can reduce TRM and improve survival.

RIC regimen was given for elderly patients or those with high comorbidity burden who would receive haplo-HSCT. The elderly patients were defined as older than 55 years. The burden of comorbidities in HSCT recipients was assessed based on the hematopoietic cell transplantation-specific comorbidity index (HCT-CI), and patients with score ≥3 were assigned as high burden. The primary end point was transplant-related mortality, and the secondary endpoints included overall survival, disease-free survival, relapse, engraftment, graft-versus-host disease (GVHD), and infections. Following time is 1 years.

Inclusion Criteria:

• Patients older than 55 years or those with HCT-CI scores of ≥3, without ISD nor URD, receiving haplo-HSCT

Exclusion Criteria:

• patients having identical sibling or unrelated donors; patients with active infection; patients having organ failure; patients with poor compliance.