Urgent haploidentical hematopoietic cell transplantation may be considered in cases of severe aplastic anemia (SAA) without human leukocyte antigen-matched donor and suffering from severe infection. However, deciding on allogeneic transplantation in the setting of active systemic infection is challenging due to poor outcomes. This report presents a case of disseminated Magnusiomyces capitatus infection in a 5-year-old male who underwent immunosuppressive therapy for hepatitis-associated SAA. To address the critical situation, granulocyte transfusion was promptly administered from the patient’s mother, followed by unmanipulated haploidentical peripheral blood stem cell transplantation from the patient’s father with posttransplant cyclophosphamide, ultimately resulting in successful rescue.

POLE codes for DNA polymerase epsilon (Pol ε) and variants of Pol ε catalytic subunit 1 can be pathogenic. We recently reported a novel POLE gene variant (p.[D1131fs];[T1891del]) which leads to bone marrow failure in two Japanese sisters. Here, we describe the successful course of hematopoietic stem cell transplantation of these two sisters. Both cases were born with congenital anemia and remained transfusion dependent. Their bone marrow showed gradually proceeding trilineage dysplasia. They both underwent HCT from an unrelated bone marrow donor and successfully achieved engraftment. Ten and eight years have passed respectively, and they are doing well without transfusion.

Background: Therapeutic drug monitoring for busulfan is important to prevent adverse events and improve outcomes in stem cell transplantation. We investigated intravenous busulfan pharmacokinetics and evaluated the utility of limited sampling strategy (LSS) as a simple method to estimate the area under the concentration-time curve (AUC). Procedure: The study comprised 87 busulfan measurements in 54 children who received intravenous busulfan between August 2015 and May 2020. AUCs were calculated from 3–5 blood sampling points in each patient, and the correlation between AUC and plasma concentrations (ng/mL) at 1, 2, 3, 4, and 6 h after initiating busulfan infusion (C1, C2, C3, C4, and C6, respectively). Results: By one-point sampling strategy, the most accurate predicted AUC was based on C6 (r2 = 0.789; precision, 11.0%) in all patients. The predicted AUC based on C6 was highly precise (r2 = 0.937; precision, 5.9%) in adolescent patients weighing > 23 kg, but the correlation was poor in infants and young children weighing ≤23 kg (r2 = 0.782; precision, 11.4%). By two-point sampling strategy, the predicted AUC based on C3 and C6 showed the most favorable performance (r2 = 0.943; precision, 6.4%), even in infants and young children, whereas the predicted AUC based on C3 and C6 was acceptable (r2 = 0.963; precision, 5.7%). Conclusions: The AUC of busulfan can be predicted based on C6 in adolescent patients. However, there was substantial inter-individual variation in busulfan pharmacokinetics in infants and young children, in whom two-point LSS was necessary for accurate AUC prediction.

Appropriate high-dose chemotherapy (HDC) for high-risk neuroblastoma has not yet been established. In Japan, a unique HDC regimen (called double-conditioning regimen) comprising two cycles of total 800 mg/m2 of thiotepa and total 280 mg/m2 of melphalan is widely used. To re-evaluate the safety and the efficacy of this regimen for high-risk neuroblastoma, the medical records of 41 patients with high-risk neuroblastoma who underwent the double-conditioning regimen followed by autologous peripheral blood stem cell rescue between 2002 and 2012 were reviewed. MYCN-amplified high-risk neuroblastomas were observed in 23 patients. All patients underwent intensive multidrug induction chemotherapy, but none underwent anti-GD2 antibody immunotherapy. The primary tumor was resected at the adequate time point. The median follow-up duration for living patients was 9.2 years (range = 5.5–14.0 years). The 5-year event-free survival (EFS) and overall survival (OS) rates from treatment initiation were 41.5% ± 7.7% and 56.1% ± 7.8%, respectively. The 5-year EFS of MYCN-amplified high-risk neuroblastoma patients was 60.9% ± 10.2%, which was significantly superior compared to MYCN-non-amplified high-risk neuroblastoma patients (16.7% ± 8.8%; P < 0.001). MYCN amplification was the most favorable prognostic factor for EFS (hazard ratio = 0.29; 95% confidence interval = 0.12–0.66). Of the 41 patients, 3 died because of regimen-related toxicity (infection, n = 2; microangiopathy, n = 1). The double-conditioning regimen with thiotepa and melphalan is effective for high-risk neuroblastoma, especially in patients with MYCN amplification. However, the double-conditioning regimen is toxic and warrants special attention in clinical practice.