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Objectives: To compare the outcomes of treosulfan‐based vs busulfan‐based conditioning regimens in allogeneic hematopoietic stem cell transplantation (HSCT) in pediatric patients. Methods: Retrospective study of all consecutive patients (2012–2019) treated with allogenic HSCT and treosulfan‐ or busulfan‐based conditioning regimens at a single center. Results: A total of 101 HSCT were included: 66 HSCT with busulfan and 35 with treosulfan. In malignant diseases (n = 62), busulfan‐based conditioning was more commonly employed than treosulfan: 82.3% vs 17.7%. However, the use of treosulfan for malignant diseases increased over time: 6.5% of HSCT in 2012–2015 vs 29% of HSCT in 2015–2019 (p =.02). The cohort of treosulfan had more children under 1‐year of age than the busulfan cohort (31 vs 13%; p =.033). The percentage of patients who received serotherapy was 73 and 89% in the nonmalignant and malignant groups, respectively. The engraftment, time to neutrophil, and platelet engraftment were not significantly different between the busulfan and the treosulfan cohorts. Rate of grade II‐IV acute GvHD was significantly higher in the busulfan cohort than the treosulfan cohort (39% vs 15%; p =.016). No differences were observed in endothelial damage complications, chronic GvHD, relapse, overall survival, and transplant‐related mortality. Conclusions: Busulfan‐based conditioning regimens are used more frequently for children undergoing allogenic HSCT, but treosulfan‐based conditioning is gaining acceptance. Treosulfan‐based conditioning is associated with lower rates of acute GvHD, and no significant differences on overall survival were observed compared with busulfan. [ABSTRACT FROM AUTHOR]

Many factors have been described to contribute to voriconazole (VCZ) interpatient variability in plasma concentrations, especially CYP2C19 genetic variability. In 2014, Hicks et al. presented data describing the correlation between VCZ plasma concentrations and CYP2C19 diplotypes in immunocompromised pediatric patients and utilized pharmacokinetic modeling to extrapolate a more suitable VCZ dose for each CYP2C19 diplotype. In 2017, in our hospital, a clinical protocol was developed for individualization of VCZ in immunocompromised patients based on preemptive genotyping of CYP2C19 and dosing proposed by Hicks et al., Clinical Pharmacogenetics Implementation Consortium (CPIC) clinical guidelines, and routine therapeutic drug monitoring (TDM). We made a retrospective review of a cohort of 28 immunocompromised pediatric patients receiving VCZ according to our protocol. CYP2C19 gene molecular analysis was preemptively performed using PharmArray®. Plasma trough concentrations were measured by immunoassay analysis until target concentrations (1–5.5 μg/ml) were reached. Sixteen patients (57.14%) achieved VCZ trough target concentrations in the first measure after the initial dose based on PGx. This figure is similar to estimations made by Hicks et al. in their simulation (60%). Subdividing by phenotype, our genotyping and TDM-combined strategy allow us to achieve target concentrations during treatment/prophylaxis in 90% of the CYP2C19 Normal Metabolizers (NM)/Intermediate Metabolizers (IM) and 100% of the Rapid Metabolizers (RM) and Ultrarapid Metabolizers (UM) of our cohort. We recommended modifications of the initial dose in 29% (n = 8) of the patients. In RM ≥12 years old, an increase of the initial dose resulted in 50% of these patients achieving target concentrations in the first measure after initial dose adjustment based only on PGx information. Our experience highlights the need to improve VCZ dose predictions in children and the potential of preemptive genotyping and TDM to this aim. We are conducting a multicenter, randomized clinical trial in patients with risk of aspergillosis in order to evaluate the effectiveness and efficiency of VCZ individualization: VORIGENIPHARM (EudraCT: 2019-000376-41). [ABSTRACT FROM AUTHOR]

Background: Naïve T-cell-depleted grafts have been employed as an ex vivo T-cell depletion (TCD) platform to prevent graft-versus-host disease (GvHD) and improve immune reconstitution by providing rapid donor memory T-cell reconstitution after allogenic hematopoietic stem cell transplantation (allo-HSCT). CD45RA- memory T cells confer protection against viruses such as cytomegalovirus, Epstein-Barr virus, and adenovirus; however, reports have shown an unexpectedly high incidence of human herpesvirus (HHV)-6B encephalitis among pediatric allo-HSCT patients.Methods: We report the first 18 consecutive allo-HSCT, 16 haplo-HSCT, and two human leukocyte antigen-matched related donors implanted with naïve TCD grafts. All donors were administered three cell products: first, a CD34+ stem cell product; second, a CD45RA+ TCD graft, followed by an adoptive natural killer (NK) cell infusion within 10 days after HSCT. The study's primary endpoint was the incidence of HHV-6B encephalitis.Results: Engraftment was achieved in 94.5% of cases; 2-year overall survival, event-free survival, and GvHD/relapse-free survival were 87.2% (95% CI 78.6-95.8), 67.3% (95% CI 53.1-81.5), and 64% (95% CI 50.5-78.1), respectively. HHV-6B reactivation occurred in 7 of the haplo-HSCT patients, six of who received a cell infusion with an NK/CD4 ratio <2. None of the patients developed encephalitis.Conclusions: In this clinical study, we show that early adoptive NK cell infusion after a 45RA+ TCD allo-HSCT graft is safe and can prevent HHV-6B encephalitis. We recommend infusing adoptive NK cells after allo-HSCT using CD45RA+ TCD grafts. [ABSTRACT FROM AUTHOR]

Objective: Describe the GETH haploidentical stem cell transplantation (haplo‐HSCT) activity in non‐malignant disease (NMDs). Methods: We retrospectively analyzed data from children with NMDs who underwent haplo‐HSCT. Results: From January 2001 to December 2016, 26 pediatric patients underwent 31 haplo‐HSCT through ex vivo T cell‐depleted (TCD) graft platforms or post‐transplantation cyclophosphamide (PT‐Cy) at 7 Spanish centers. Five cases employed unmanipulated PT‐Cy haplo‐HSCT, 16 employed highly purified CD34+ cells, and 10 employed ex vivo TCD grafts manipulated either with CD3+CD19+ depletion, TCRαβ+CD19+ selection or naive CD45RA+ T‐cell depletion. Peripheral blood stem cells were the sole source for patients following TCD haplo‐HSCT, and bone marrow was the source for one PT‐Cy haplo‐HSCT. The most common indications for transplantation were primary immunodeficiency disorders (PIDs), severe aplastic anemia, osteopetrosis, and thalassemia. The 1‐year cumulative incidence of graft failure was 27.4%. The 1‐year III‐IV acute graft‐versus‐host disease (GvHD) and 1‐year chronic GvHD rates were 34.6% and 16.7%, respectively. The 2‐year overall survival was 44.9% for PIDs, and the 2‐year graft‐versus‐host disease‐free and relapse‐free survival rate was 37.6% for the other NMDs. The transplantation‐related mortality at day 100 was 30.8%. Conclusion: Although these results are discouraging, improvements will come if procedures are centralized in centers of expertise. [ABSTRACT FROM AUTHOR]