仲宗根 秀樹

Unrelated single-unit cord blood transplantation (CBT) is a valuable alternative donor source for patients without matched related or unrelated donors. Although initial concerns included limited cell dose, delayed haematopoietic recovery and higher early mortality, advancements in transplant practices may have led to improved outcomes. However, it remains uncertain whether these improvements extend to the most recent years. We conducted a nationwide, registry-based retrospective study of 15 816 patients who received unrelated single-unit CBT in Japan and analysed across four time periods: 2003-2007, 2008-2012, 2013-2017 and 2018-2022. Overall survival (OS) improved significantly across time periods, with 3-year OS increasing from 38.8% (2003-2007) to 54.4% (2018-2022; p < 0.001). Similarly, 100-day non-relapse mortality declined from 19.6% to 9.5% (p < 0.001). Neutrophil and platelet engraftment rates also rose steadily, reaching 89.6% and 78.0%, respectively, in the most recent period. The most notable improvement in 100-day OS occurred among patients aged ≥60 years. Early mortality within 100 days due to bacterial and fungal infections, graft failure, haemorrhage and graft-versus-host disease (GVHD) significantly decreased over time. This study shows clear and consistent improvements in transplant outcomes, especially in the most recent 5-year period.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is a lethal complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). According to the 2016 European Society for Blood and Marrow Transplantation criteria, SOS/VOD is classified into classical SOS/VOD and late-onset SOS/VOD, but their similarities and differences remain unclear. Here we retrospectively investigated the incidence, risk factors, and impact on transplant outcomes of classical and late-onset SOS/VOD in 16 518 allo-HSCT recipients using the Japanese nationwide registry data. The cumulative incidences of classical and late-onset SOS/VOD were 2.5% and 2.2%, with a median onset of 13 and 42 days after transplantation, respectively. Both patients with classical (hazard ratio [HR], 3.45; 95% CI, 3.07-3.87) and late-onset (HR, 3.98; 95% CI, 3.51-4.51) SOS/VOD had a significantly worse overall survival compared with those without. The risk factors for classical and late-onset SOS/VOD are different. Hepatic comorbidities, high-risk diseases, use of melphalan (MEL), and myeloablative conditioning are associated with both types of SOS/VOD. Whereas poor performance status, a prior history of transplantation, and positive hepatitis C virus are associated with only classical SOS/VOD, allo-HSCT from cord blood or related human leukocyte antigen-haploidentical donors, use of total body irradiation and busulfan (BU), and tacrolimus-based graft-versus-host disease prophylaxis are associated with only late-onset SOS/VOD. In particular, the incidence of late-onset SOS/VOD is much higher in patients receiving both BU- and MEL-containing conditioning regimens. These findings suggest that different monitoring and treatment approaches are necessary for allo-HSCT recipients at high risk for classical and late-onset SOS/VOD.

Allogeneic hematopoietic stem cell transplantation (HSCT) from HLA-matched donors is the gold standard. However, haploidentical stem cell transplantation using posttransplant cyclophosphamide (PTCY-haplo) and cord blood transplants (CBTs) are alternatives when HLA-matched donors are not available. Using Japanese registry data, we evaluated the impact of haploidentical donor age on posttransplant outcomes by comparing PTCY-haplo and CBT. We analyzed data for 5161 patients aged 16 to 70 years who received their first HSCT for acute leukemia, myelodysplastic syndrome, or chronic myeloid leukemia. Haploidentical donors were categorized as "younger" (aged <40 years) or "older" (aged ≥40 years), and the patients were divided into younger (aged <50 years) and older (aged ≥50 years) cohorts. In the older cohort, PTCY-haplo from younger donors had better overall survival (OS; 55.5% vs 50.8%, P = .006), lower nonrelapse mortality (NRM; 17.3% vs 28.6%, P < .001), and higher relapse rates (33.0% vs 24.9%, P = .017) than with CBT. PTCY-haplo from older donors had comparable OS (44.1% vs 50.8%, P = 1.00), NRM (27.3% vs 28.6%, P = 1.00), and relapse (29.2% vs 24.9%, P = .90) to that with CBT. In the younger cohort, PTCY-haplo from younger and older donors showed OS, NRM, and relapse comparable with CBT. In the older cohort, cumulative incidence of acute graft-versus-host disease (GVHD) was higher with CBT than with PTCY-haplo, regardless of donor age. However, in the younger cohort, acute GVHD was lower in PTCY-haplo from younger donors than with CBT. PTCY-haplo from younger donors to older patients offers better clinical outcomes than CBT.

The SARS-CoV-2 pandemic disrupted healthcare systems worldwide, particularly affecting hematopoietic stem cell transplantation (HSCT) activities. Understanding the impact of the SARS-CoV-2 pandemic on transplant practices, especially in Japan, where cord blood transplantation (CBT) is prevalent, is crucial. A total of 40,444 allogeneic HSCT cases in Japan between 2011 and 2021 were examined using an interrupted time series analysis to assess the impact of COVID-19 on CBT utilization. Following the SARS-CoV-2 pandemic, CBT cases demonstrated a significant increase (11.06 [95% confidence interval (CI): 1.87 to 20.25] cases per month), whereas bone marrow transplantation cases decreased, by 10.74 cases per month (95% CI, -19.84 to -1.63 cases per month). Total HSCT cases remained stable with a level change of 5.47 cases per month (95% CI, -10.07 to 21.01 cases per month) and a trend change of -1.11 cases per month (95% CI, -2.22 to 0.004 cases per month). The interrupted time series analysis showed significantly increased CBT cases in Japan, highlighting its crucial role as an alternative transplant source during the pandemic. CBT offset the impact of the decrease in bone marrow transplantation and contributed to the maintenance of HSCT activity in Japan during the unprecedented crisis.