Impact of in Vivo Lymphodepletion on Outcome in Children with Nonmalignant Disorders Receiving Peripheral Blood Stem Cell Transplantation.

Peripheral blood stem cell transplantation (PBSCT) with in vivo lymphodepletion can provide faster neutrophil recovery with limited risk of severe graft-versus-host disease (GVHD) in children with nonmalignant disorders (NMDs). We aimed to provide an historical comparison of these 2 strategies regarding the prevalence of GVHD, viral reactivation, timing of immune reconstitution, and final outcomes. Data on 98 children undergoing PBSCT were collected from 5 European pediatric transplantation centers. Only patients with NMDs receiving treosulfan or myeloablative busulfan conditioning and 9-10/10 HLA-matched transplant were included. The patients were divided into 2 groups according to in vivo lymphodepletion with antithymocyte globulin (ATG) or with alemtuzumab. We compared rates of acute and chronic GVHD; Epstein-Barr virus, cytomegalovirus, and adenovirus reactivation; chimerism; lymphocyte recovery; overall survival (OS) and event-free survival (EFS) between the 2 groups. The rate of severe acute GVHD (grade III-IV) was significantly higher in patients receiving ATG (26% vs 10% in alemtuzumab recipients; P < .05), whereas viral reactivations occurred with a similar rate in the 2 groups (alemtuzumab, 56%; ATG, 57%). Alemtuzumab was the major risk factor for delayed T cell immune reconstitution in the first 3 months after transplantation (odds ratio [OR], 6.0; 95% confidence interval [CI], 1.8 to 19; P < .005). Extended chronic GVHD, ADV reactivation, slower CD3+ cell recovery, and HLA-mismatch reduced the probability of survival. Infections were the main cause of mortality in our cohort, and delayed T cell recovery was significantly associated with mortality in multivariate analysis (OR, 12; 95% CI, 1.2 to 114; P < .05). Ultimately, no differences in OS and EFS survival were seen between the ATG and alemtuzumab groups. ATG and alemtuzumab showed similar impacts on outcomes of children undergoing PBSCT for NMDs. The 2 strategies of in vivo lymphodepletion showed specific drawbacks that were counterbalanced by benefits that ultimately led to a comparable survival rate. A patient-centered lymphodepletion strategy can be advised in children undergoing PBSCT for NMDs, by favoring T cell recovery in the presence of invasive infection or GVHD prevention in high-risk mismatched donor transplantation.