神田 善伸

BACKGROUND: Sex-mismatched allogeneic hematopoietic cell transplantation (allo-HCT), particularly with female donors and male recipients (FtoM), is known to be associated with an increased risk of chronic graft-versus-host disease (GVHD) and non-relapse mortality (NRM). This adverse effect of FtoM allo-HCT is considered to result from allo-immunity against Y-chromosome antigens. However, it has not been elucidated whether the adverse impact of FtoM allo-HCT varies by recipient age. OBJECTIVE: This study aims to examine the effect of sex-mismatch on clinical outcomes in allo-HCT from human leukocyte antigen (HLA)-matched donors, stratified by recipient age group. STUDY DESIGN: Using a Japanese transplantation registry database, we analyzed 10392 patients (n = 2169, 2573, and 5650 in FtoM, MtoF, and sex-matched allo-HCT, respectively) with standard-risk hematological malignancies who had undergone their first allo-HCT from HLA-matched related or unrelated donors without in vivo T-cell depletion between 2008 and 2022. The impact of sex-mismatch on clinical outcomes was separately assessed by recipient age groups: ≤ 15, 16-39, and ≥ 40 years. The primary endpoint was overall survival (OS). Secondary endpoints included disease-free survival, NRM, and the cumulative incidences of acute and chronic GVHD. RESULTS: In recipients aged ≥ 40 years, OS and NRM at 5 years post-HCT were significantly worse in the FtoM group compared with the MtoF and sex-matched groups (5-year OS 49.5% vs 59.6% vs 57.1%, P < 0.001; 5-year NRM 27.9% vs 21.9% vs 23.0%, P < 0.001), while no differences were observed among the FtoM, MtoF, and sex-matched groups in recipients aged ≤ 15 years or 16-39 years. Multivariate analyses confirmed that FtoM allo-HCT was significantly associated with increased mortality only in recipients aged ≥ 40 years (hazard ratio [HR] for OS 1.31, P < 0.001; HR for NRM 1.44, P < 0.001). The FtoM group in recipients aged ≥ 40 years frequently experienced fatal infection and fatal non-infectious pulmonary complications. In addition, we confirmed that the adverse effect of FtoM allo-HCT on OS similarly appeared only in recipients aged ≥ 40 years in both sub-cohorts divided by a median of donor age (40 years). CONCLUSION: The adverse impact of FtoM allo-HCT on survival outcomes differed according to recipient age. Our findings suggest that female donors should be avoided, especially in older male recipients undergoing allo-HCT.

ABSTRACT While venetoclax‐based combinations have shown promising results in acute myeloid leukemia (AML), the remission duration is generally short, warranting strategies to further improve efficacy and overcome resistance. Here, we show that the natural quassinoid brusatol induces cell‐cycle arrest and apoptosis in multiple AML cell lines while enhancing venetoclax efficacy irrespective of inherent or acquired resistance. Mechanistically, brusatol increased p53 protein expression, leading to upregulation of its target genes/proteins, including CDKN1A (p21) and BBC3 (PUMA). Genetic deletion of TP53 attenuated brusatol‐induced apoptosis and its synergy with venetoclax, supporting p53 activation as a central mechanism underlying the anti‐leukemia response. Furthermore, the combination synergistically decreased mitochondrial membrane potential and respiratory activity, causing accumulation of reactive oxygen species in AML cells. Although brusatol and venetoclax exhibited limited effects individually, their combination markedly reduced leukemia burden and significantly prolonged survival in three independent cell line‐derived xenograft models, including venetoclax‐resistant and ‐refractory models. Notably, brusatol increased normal leukocyte and platelet counts while reducing leukemic infiltration in both bone marrow and extramedullary sites. These findings provide mechanistic insight into the synergistic effects of the brusatol‐venetoclax combination, supporting further evaluation of this therapeutic strategy in myeloid leukemias.

Post-transplant relapse remains a major cause of treatment failure in adult B-cell acute lymphoblastic leukemia (ALL). The introduction of inotuzumab ozogamicin (InO) and blinatumomab (Blina) has expanded salvage options; however, their impact on outcomes and safety in patients relapsing after allogeneic stem cell transplantation has not been fully defined. To evaluate the impact of the availability of InO and Blina on clinical outcomes in adult B-cell ALL patients with post-transplant relapse, and to assess the safety of these agents in the post-transplant setting. We retrospectively analyzed 150 adult patients with B-cell ALL who relapsed after the first allogeneic stem cell transplantation. Patients were divided according to the time of their post-transplant relapse based on the approvals of InO and Blina in Japan: the pre-InO/Blina group (n = 95) and the post-InO/Blina group (n = 55). Outcomes were analyzed separately for Philadelphia chromosome (Ph)-negative and Ph-positive ALL. Overall survival (OS) after post-transplant relapse, complete remission (CR) rates as the best response before a second transplantation or last follow-up, and outcomes after a second transplantation were compared between groups. Adverse events associated with post-transplant use of InO and Blina were also evaluated. Among 95 patients with Ph-negative ALL, outcomes were significantly better in the post-InO/Blina group than in the pre-InO/Blina group, with the 2-year OS after post-transplant relapse improving from 19% to 51% (P = .003) and, among 88 treated patients, the CR rate increasing from 36% to 77% (P < .001). Multivariable analyses identified the time of post-transplant relapse and disease status at the first transplantation as independent prognostic factors for OS. Among 43 patients who underwent a second transplantation, the 2-year OS after second transplantation improved from 27% in the pre-InO/Blina group to 55% in the post-InO/Blina group (P = .029). In contrast, among 55 patients with Ph-positive ALL, OS after post-transplant relapse did not differ between groups. Among 32 patients treated with InO after post-transplant relapse, no patient developed veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) during InO therapy; however, 5 of 17 patients (29%) who subsequently underwent the second transplantation developed VOD/SOS. An interval of <2.5 months between InO and the second transplantation was associated with a higher VOD/SOS risk (56% versus 0%, P = .029). Among 30 patients treated with Blina, cytokine release syndrome occurred in 53% (grade 3 to 4, 7%) and immune effector cell-associated neurotoxicity syndrome in 13% (grade 3, 3%), with no fatal events. The prognosis of adult Ph-negative B-cell ALL after post-transplant relapse improved substantially in the post-InO/Blina era, including improved survival after a second transplantation. Overall, the safety profiles of InO and Blina in the post-transplant setting were acceptable, although VOD/SOS remains an important concern in patients proceeding to a second transplantation after InO.

OBJECTIVES: Bacteraemia and cytomegalovirus (CMV) infection are major infectious complications after allogeneic haematopoietic cell transplantation (HCT). However, their bidirectional relationship, particularly in the setting of letermovir (LTV) prophylaxis, remains unclear. We investigated the bidirectional associations between bacteraemia and CMV infection and their impact on transplantation outcomes. We also evaluated the effect of LTV prophylaxis on these associations. METHODS: Using a nationwide Japanese transplant registry database, we analysed 23,841 patients who underwent their first allogeneic HCT between 2008 and 2022. Multivariable Cox proportional hazards models with time-dependent covariates were used to evaluate bidirectional associations between bacteraemia and clinically significant CMV infection (csCMVi). RESULTS: csCMVi was associated with an increased risk of subsequent bacteraemia (adjusted hazard ratio [aHR], 1.48; 95% CI, 1.33-1.64), with a stronger association among patients in the LTV group (aHR, 2.59; 95% CI, 1.87-3.60) than among those in the no-LTV group (aHR, 1.30; 95% CI, 1.16-1.46). Conversely, bacteraemia was modestly associated with an increased risk of csCMVi overall (aHR, 1.06; 95% CI, 1.01-1.11), but this association was observed only in the LTV group (aHR, 1.61; 95% CI, 1.40-1.85). These bidirectional associations were consistent in the LTV era and in patients without grade II-IV acute graft-versus-host disease. The findings were robust in sensitivity analyses, including landmark and propensity score-matched analyses. In propensity score-matched cohorts, both bacteraemia and csCMVi were associated with higher nonrelapse mortality (NRM; defined as death without relapse of the underlying malignancy) and inferior overall survival (OS), regardless of LTV use. CONCLUSIONS: Bacteraemia and csCMVi were bidirectionally associated after allogeneic HCT, particularly in the LTV group. Both bacteraemia and csCMVi were consistently associated with higher NRM and inferior OS, regardless of LTV prophylaxis. These findings highlight the need for integrated infection management strategies, particularly in the LTV era.

Registry analysis of first allogeneic transplant in HLA-homozygous recipients.Overall survival did not significantly differ with related donor hetero-to-homo or cord blood hetero-to-homo transplantation.Cord blood homo-to-homo transplantation was associated with inferior survival in the primary analysis.

UNLABELLED: Ibrutinib, a Bruton tyrosine kinase inhibitor, has improved outcomes for patients with relapsed or refractory mantle cell lymphoma, yet prognosis remains inadequate for many. The choice between high-dose therapy with autologous hematopoietic cell transplantation (HCT) and allogeneic HCT remains a topic of debate in this patient population. This Japanese retrospective study (2017–2023) analyzed 155 patients with relapsed or refractory mantle cell lymphoma receiving autologous (n = 105) or allogeneic HCT (n = 50). Autologous and allogeneic HCT showed comparable efficacy, with similar median OS (28 vs. 27 months). However, outcome predictors differed significantly. Autologous HCT: age > 60 years predicted worse OS (hazard ratio [HR] = 2.73) and allogeneic HCT: early progression surrogate based on diagnosis-to-HCT interval ≤ 24 months and relapsed or refractory status at HCT (HR = 4.10) and non-complete remission (HR = 3.53) correlated with poorer outcomes. Ibrutinib integration demonstrated critical benefits: post-autologous relapse patients receiving ibrutinib had superior 2-year OS (57% vs. 25%, P = 0.035), and no transplant-related mortality occurred in allogeneic HCT patients on ibrutinib (n = 10). This study confirms HCT use in the ibrutinib era, highlighting age, disease kinetics, and targeted therapy as key prognostic factors, and supports risk-adapted strategies combining HCT with novel agents like ibrutinib to optimize outcomes for high-risk mantle cell lymphoma. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-026-47347-3.

Allogeneic haematopoietic stem cell transplantation (allo-HSCT) offers a curative potential for myelodysplastic syndrome (MDS) and myelodysplastic/myeloproliferative neoplasm (MDS/MPN). We examined survival trends using a nationwide database of 7175 patients who underwent their first allo-HSCT between 1998 and 2022. Overall mortality decreased over time in patients with early MDS (hazard ratio [HR] 0.79, 95% confidence interval [CI] 0.65-0.97, p = 0.026 in 2013-2017; HR 0.54, 95% CI 0.42-0.70, p < 0.001 in 2018-2022), advanced MDS (HR 0.80, 95% CI 0.71-0.90, p < 0.001 in 2013-2017; HR 0.74, 95% CI 0.65-0.85, p < 0.001 in 2018-2022), chronic myelomonocytic leukaemia (HR 0.45, 95% CI 0.32-0.64, p < 0.001 in 2013-2017; HR 0.53, 95% CI 0.37-0.74, p < 0.001 in 2018-2022) and atypical chronic myeloid leukaemia (HR 0.32, 95% CI 0.13-0.80, p = 0.016 in 2013-2017; HR 0.26, 95% CI 0.10-0.68, p = 0.006 in 2018-2022). These decreases in overall mortality were mainly attributable to reductions in non-relapse mortality. Meanwhile, no significant difference in overall mortality was observed in patients with MDS/MPN-unclassified and therapy-related myeloid neoplasm. Across all disease subtypes, relapse incidence did not significantly decrease over time, highlighting persistent challenges in reducing the risk of post-transplant relapse.

Using data from a nationwide Japanese registry, we evaluated the impact of the total body irradiation (TBI) dose in reduced-intensity conditioning (RIC) for allogeneic hematopoietic cell transplantation (allo-HCT) in patients with acute myeloid leukemia (AML). Adults undergoing their first allo-HCT with RIC between 2010 and 2021 were classified into three groups: non-TBI, low-TBI (2 to < 4 Gy), or moderate-TBI (4-8 Gy). Outcomes were analyzed separately for patients in complete remission (CR, n = 1949) and those in the non-CR group (n = 1484). Non-TBI was associated with higher overall mortality than low-TBI (hazard ratio [HR], 1.27; 95% confidence interval [CI], 1.03-1.56 in CR; HR, 1.19; 95% CI, 1.00-1.42 in non-CR). Moderate-TBI showed no significant difference in overall mortality compared to low-TBI (HR, 0.96; 95% CI, 0.80-1.15 in CR; HR, 0.89; 95% CI, 0.77-1.05 in non-CR). Among patients in the CR group with matched sibling donors, moderate-TBI reduced overall mortality (HR, 0.33; 95% CI, 0.17-0.64) and relapse (HR, 0.29; 95% CI, 0.12-0.69). In cord blood transplantation, non-TBI increased relapse in CR (HR, 2.73; 95% CI, 1.48-5.06) and overall mortality in non-CR (HR, 1.62; 95% CI, 1.19-2.19). In haploidentical transplants, non-TBI increased relapse (HR, 5.52; 95% CI, 1.72-17.72 in CR; HR, 1.54; 95% CI, 1.04-2.30 in non-CR). The incidence of secondary primary malignancies did not differ according to the use or dose of TBI. In conclusion, adding low- or moderate-TBI to RIC may improve disease control and survival without increasing non-relapse mortality.

Summary The clinical impact of immunosuppression termination (IST) after allogeneic haematopoietic stem cell transplantation (allo‐HSCT) remains to be fully elucidated. This study was aimed at assessing the impact of IST within 2 years after transplantation on subsequent clinical outcomes. We analysed data for patients from the Transplant Registry Unified Management Program 2 (TRUMP 2) database who survived without progression for at least 2 years after allo‐HSCT. Of the 5061 patients whose median age was 48 (range: 0–79) years, 2320 discontinued immunosuppressive therapy within 2 years (IST group), while 2741 did not (non‐IST group). The 4‐year overall survival (OS) rate was significantly higher in the IST group than in the non‐IST group (95.3% vs. 90.8%; p  &lt; 0.01). The 4‐year cumulative incidence of non‐relapse mortality (NRM) was significantly lower in the IST group than in the non‐IST group (3.5% vs. 8.6%; p  &lt; 0.01). This reduction in NRM was consistent across major causes, including graft‐versus‐host disease (GVHD)‐related mortality, infection‐related mortality and organ failure‐related mortality. Immunosuppressive therapy beyond 2 years after allo‐HSCT was associated with inferior OS. Our findings suggest that the optimal transplant strategy is necessary to avoid long‐term immunosuppression for improving clinical outcomes in allo‐HSCT recipients.

BACKGROUND: The advent of novel therapeutic agents has improved the prognosis of multiple myeloma (MM). However, autologous stem cell transplantation (ASCT) remains a key treatment option for eligible patients. While stem cell mobilization using cyclophosphamide and granulocyte colony-stimulating factor (G-CSF) has long been the standard approach, the introduction of plerixafor (PLER) has led to broader adoption of G-CSF±PLER-based mobilization, offering improved scheduling flexibility. Nevertheless, real-world data on current mobilization practices and their effects on post-ASCT outcomes remain limited. METHODS: We evaluated mobilization strategies and their associations with clinical outcomes in MM patients who underwent ASCT between 2019 and 2022. A total of 3,319 patients were analyzed, including 743 patients mobilized with cyclophosphamide and 2,576 mobilized with G-CSF±PLER. The primary endpoint was 2-year overall survival (OS). Multivariate analysis and propensity score matching were performed to identify factors associated with superior OS. RESULTS: The 2-year OS rates were 89.7% (95% CI: 87.0-91.8) and 93.2% (95% CI: 91.8-94.3) in the cyclophosphamide and G-CSF groups, respectively. Multivariate analysis showed that age <65 years (P < 0.001), lower ISS stage (P < 0.001), good performance status (P < 0.001), G-CSF mobilization (P = 0.005), and deep response pre-ASCT (P < 0.001) were independent predictors of superior OS. Propensity score matching analysis demonstrated significantly better OS in the G-CSF group than in the cyclophosphamide group (P = 0.041). Among patients achieving complete or very good partial response (CR/VGPR) pre-ASCT, OS did not differ between the groups; however, among patients who did not reach CR or VGPR pre-ASCT, the G-CSF group showed significantly better OS than the cyclophosphamide group. CONCLUSIONS: G-CSF‒based mobilization may offer prognostic advantages after ASCT, particularly in patients with suboptimal pre-ASCT response.

BACKGROUND: Previous reports have suggested an association between cytomegalovirus (CMV) infection and bacterial or fungal infections after allogeneic hematopoietic cell transplantation (HCT). This study aimed to examine the relationship between letermovir (LTV) prophylaxis and the incidence of bacteremia and invasive fungal infections. METHODS: Using a Japanese transplant registry database, we analyzed 19,531 patients who underwent their first allogeneic HCT from 2011 to 2022. Patients who initiated LTV prophylaxis within the first week post-transplantation were classified as the LTV group. RESULTS: A total of 4915 patients in the LTV group and 14,616 in the No LTV group were analyzed. The incidence of bacteremia by day 100 was significantly lower in the LTV group compared to the No LTV group (17.4 % vs. 21.7 %, P < 0.001). In the multivariate analysis, LTV prophylaxis (HR 0.75, 95 %CI: 0.69-0.81) was found to be significantly associated with a reduced risk of bacteremia, along with neutrophil engraftment. Age >50 years, male, non-remission status, alternative donors, higher values of the hematopoietic cell transplantation-comorbidity index, poor performance status, and grade II-IV acute graft-versus-host disease were associated with an increased risk of bacteremia. LTV was associated with a reduced risk of bacteremia both within 30 days (HR 0.74, 95 %CI: 0.68-0.81) and beyond 30 days (HR 0.76, 95 %CI: 0.66-0.89) after HCT. Conversely, it was not associated with the risk of invasive aspergillosis or candidemia. CONCLUSIONS: LTV prophylaxis significantly reduced the risk of bacteremia. However, it was not associated with the risk of invasive fungal infections.

Despite the increasing number of cancer survivors, the impact of prior solid tumors and their treatment modality on outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains unclear. This multi-center retrospective study compared transplant outcomes in allo-HSCT recipients with and without a history of solid tumors. Of 5,850 adult patients who underwent first allo-HSCT, 303 (5.2%) had a prior solid tumor. After propensity score matching, overall survival (OS) and cumulative incidences of relapse, non-relapse mortality (NRM), and acute and chronic graft-versus-host diseases were almost comparable between the two groups. Progression or recurrence of solid tumors after allo-HSCT occurred in only eight cases (2.8%). Importantly, patients who received both chemotherapy and radiation therapy (Chemo + RT) for prior solid tumors had significantly worse OS (35.3% vs. 54.1% [P < 0.001] vs. 56.8% [P < 0.001] at 2 years) and higher NRM (36.2% vs. 18.7% [P = 0.002] vs. 19.3% [P = 0.001] at 2 years) compared to patients who received other treatment modalities for prior solid tumors or patients without prior solid tumors. These findings highlight the feasibility of allo-HSCT in selected patients with prior solid tumors, while demonstrating the negative impact of Chemo + RT on outcomes after allo-HSCT.

HLA class I allele loss in acquired aplastic anemia (AA) represents an immune escape from the T cell-mediated pathogenesis. We investigated the impact of loss-prone HLA alleles on the hematopoietic cell transplantation (HCT) outcomes using registry data of 875 Japanese patients with acquired AA. HLA associations were evident exclusively among 399 patients who received HCT within 1 year of the diagnosis, consistent with the predominance of HLA loss in this group. A set of five HLA alleles with the highest propensity for loss (HLA-A*02:01, HLA-A*02:06, HLA-A*31:01, HLA-B*40:02, and HLA-B*54:01) was the strongest predictor of post-transplant survival among all possible allele combinations (5-year survival, 80.3% vs. 54.4%; p < 0.0001), partly due to improved engraftment and pre-transplant conditions. Another set (HLA-A*33:03, HLA-B*07:02, HLA-B*44:03, HLA-B*52:01, and HLA-B*54:01)-less frequently lost in AA and underrepresented in Epstein-Barr virus (EBV)-related diseases outside AA-was associated with an increased risk of post-transplant lymphoproliferative disorders (5-year incidence, 10.2% vs. 1.8%; p = 0.00019), suggesting that the loss of protective alleles against EBV during AA pathogenesis may predispose to EBV-driven lymphoproliferations. These associations were determined by recipient, not donor, HLA. Therefore, specific HLA class I alleles and their potential loss significantly influence the HCT outcomes in acquired AA.

Mixed-phenotype acute leukemia (MPAL) is associated with poor prognosis. Although allogeneic hematopoietic stem cell transplantation (allo-HSCT) can achieve long-term survival, optimal transplantation strategies remain unclear. We analyzed a national registry of adult patients with MPAL who underwent allo-HSCT between 2008 and 2022 in Japan. Among 417 patients, median age at transplant was 44 years (interquartile range, 32-55); 61% were male, 20% were BCR::ABL1-positive, and 66% underwent transplant during the first complete remission (CR; CR1). At 5 years posttransplant, overall survival (OS) was 54%, disease-free survival was 49%, relapse was 28%, and nonrelapse mortality was 23%. Multivariate analysis identified older age (adjusted hazard ratio [aHR], 1.78 [95% confidence interval (CI), 1.11-2.84] for ages 50-59 years; aHR, 2.65 [95% CI, 1.54-4.55] for ≥60 years; both vs <40 years), male sex (aHR, 1.56; 95% CI, 1.07-2.27), Eastern Cooperative Oncology Group performance status scale ≥2 (aHR, 3.05; 95% CI, 1.72-5.40), BCR::ABL1 -negative status (aHR, 1.64; 95% CI, 1.02-2.64), advanced disease status (aHR, 1.642 [95% CI, 0.80-3.36] for second CR; aHR, 4.01 [95% CI, 2.61-6.15] for third or higher CR, or non-CR vs CR1), and low conditioning intensity (aHR, 2.49 [95% CI, 1.21-5.13] for low transplant conditioning intensity [TCI] vs high TCI) as adverse prognostic factors for OS. A propensity score-matched comparison with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) during the same period showed that MPAL did not have significantly worse prognosis than AML or ALL. These findings suggest that allo-HSCT offers long-term survival in MPAL, with outcomes not inferior to those of AML and ALL.

Abstract Leukemia cells are consistently subjected to higher oxidative stress than normal cells. To mitigate reactive oxygen species (ROS) overload, which can trigger various forms of cell death, leukemia cells employ a robust antioxidant defense system and maintain redox homeostasis. Recent evidence suggests that dimethyl fumarate (DMF), a derivative of fumarate, inactivates the antioxidant glutathione (GSH), thereby inducing oxidative stress and metabolic dysfunction, eventually leading to cell death in cancer cells. In this study, we observed that DMF decreases the GSH/oxidated GSH ratio and increases intracellular ROS levels, the extent of which is closely correlated with cell death, in acute myeloid leukemia (AML) cell lines. DMF reduced the mitochondrial membrane potential and oxidative phosphorylation (OXPHOS), effects that were almost fully restored by the antioxidant N-acetylcysteine, suggesting that these responses are ROS-dependent. Electron microscopy and inhibition assays revealed that apoptosis, rather than necroptosis or ferroptosis, is the predominant form of cell death of AML cells following DMF treatment. Notably, the combination of DMF and the BCL-2 selective BH3-mimetic venetoclax induced marked cell death in AML cells, including venetoclax-refractory BCL-2 low expressing U937 and acquired venetoclax-resistant MOLM-14 cells. This combination also caused greater mitochondrial depolarization and a more profound reduction in OXPHOS activity than either agent alone. Collectively, our findings indicate that DMF exerts potent anti-leukemia activity in AML cells and sensitizes cells to venetoclax treatment by synergistically disrupting mitochondrial integrity through ROS accumulation.

Summary Severe graft‐versus‐host disease (GVHD) remains a major complication of allogeneic haematopoietic stem cell transplantation (allo‐HSCT), necessitating optimal immunosuppressive strategies. This retrospective study used data from the Japanese Transplant Registry Unified Management Program to compare three methotrexate (MTX)‐dosing regimens for GVHD prophylaxis in patients undergoing human leucocyte antigen (HLA)‐matched allo‐HSCT: a low‐dose 3‐day regimen (Ld3:10 mg/m² on day 1, 7 mg/m² on days 3 and 6), a low‐dose 4‐day regimen (Ld4: Ld3 with an additional 7 mg/m² on day 11) and an original‐dose 3‐day regimen (Od3: 15 mg/m² on day 1, 10 mg/m² on days 3 and 6). Among 2537 analysed patients, Ld3 was the most commonly used regimen. Multivariate analyses showed no significant differences in the cumulative incidence of grade II–IV acute GVHD among regimens. However, Od3 was associated with an increased risk of grade III–IV acute GVHD, and Ld4 was linked to delayed neutrophil engraftment. This study is the first large‐scale retrospective analysis of the impact of different MTX‐dosing regimens on the outcomes of HLA‐matched allo‐HSCT, providing valuable insights into optimal MTX‐dosing strategies in clinical practice.

Overall response (OR) that combines complete (CR) and partial responses (PR) is the conventional end point for acute graft-versus-host disease (GVHD) trials. Because PR includes heterogeneous clinical presentations, reclassifying PR could produce a better end point. Patients in the primary treatment cohort from the Japanese Society for Transplantation and Cellular Therapy (JSTCT) were randomly divided into training and validation sets. In the training set, a classification and regression tree algorithm generated day 28 refined response (RR) criteria based on symptoms at treatment and day 28. We then evaluated RR for primary and second-line treatments, using the area under the receiver operating characteristic curve (AUC) and negative predictive value (NPV) for 6-month nonrelapse mortality as performance measures. RR considered patients with grade 0/1 at day 28 without additional treatment as responders. RR for primary treatment produced higher AUCs than OR with small improvement of NPVs in both validation sets: JSTCT (AUC, 0.73 vs 0.69 [P < .001]; NPV, 92.0% vs 89.6% [P < .001]) and the Mount Sinai Acute GVHD International Consortium (MAGIC; AUC, 0.71 vs 0.68 [P = .032]; NPV, 90.9% vs 89.8% [P = .009]). RR for second-line treatment produced similar AUCs but much higher NPVs than OR in both validation sets of JSTCT (AUC, 0.64 vs 0.63 [P = .775]; NPV, 74.5% vs 66.0% [P < .001]) and MAGIC (AUC, 0.67 vs 0.64 [P = .105]; NPV, 86.8% vs 76.1% [P = .004]). Classifying persistent but mild skin symptoms as responses and residual lower gastrointestinal GVHD as nonresponses were major drivers in improving the prognostic performance of RR. Our externally validated day 28 RR would serve as a better end point than conventional criteria in future first- and second-line treatment trials.

Patient age might influence donor selection priorities in allogeneic hematopoietic stem cell transplantation (allo-HCT), due to the differences in donor age, organ function, and resistance to graft-versus-host disease between younger and older patients. We compared the transplant outcomes among human leukocyte antigen (HLA)-matched related donors (M-RDs, n=4,106), HLA 1-antigen-mismatched related donors (1MM-RDs, n=592), HLA 2-3-antigen-mismatched related donors (23MM-RDs, n=882), HLA-matched unrelated donors (M-UDs, n=3,927), HLA 1-locus-mismatched unrelated donors (1MM-UDs, n=2,474), and unrelated cord blood units (U-CBs, n=5,867) between patients aged.

Primary plasma cell leukemia (pPCL) is a rare and aggressive subtype of plasma cell malignancy. Although hematopoietic stem cell transplantation (HCT), including autologous HCT (auto-HCT) and allogeneic HCT (allo-HCT), is widely used, an optimal treatment strategy is undetermined. We retrospectively analyzed patients with pPCL who underwent HCT between 2006 and 2022 in Japan using Japanese registry data. Overall, 182 patients (117 and 65 who underwent auto-HCT and allo-HCT, respectively) were included. Patients in the allo-HCT group were younger, had more advanced disease, and underwent tandem HCT more frequently than did those in the auto-HCT group. There was no statistically significant difference in overall survival (OS) between the groups (P=0.46), with a median OS of 3.2 years (95% CI 2.1-4.3 years) in the auto-HCT group and 1.4 years (95% CI 0.8-3.9 years) in the allo-HCT group. Comparing the four different transplantation strategies (single auto-HCT, single allo-HCT, tandem autologous-autologous HCT, and tandem autologous-allogeneic HCT), the single allo-HCT group had the poorest OS because of early mortality. Tandem autologous-allogeneic HCT appeared to provide better long-term survival. In the multivariate analysis, disease status, Eastern Cooperative Oncology Group Performance Status, and tandem transplantation were significant factors influencing OS. A matched-pair analysis using propensity scores revealed no significant differences in OS between the auto-HCT and allo-HCT groups. However, the allo-HCT group appeared to have better long-term survival than the auto-HCT group. Allogeneic transplantation, including tandem autologous-allogeneic-HCT, may offer long-term survival benefits with appropriate patient selection. Further studies are warranted to optimize the transplantation strategies and pre- and post-transplantation treatments for pPCL.

The optimal alternative donor type for patients lacking human leucocyte antigen (HLA)-matched related or unrelated donors remains unclear. In comparative studies evaluating donor types, graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) represents a well-established end-point but has limitations. The win ratio approach addresses these limitations by analysing multiple end-points with varying severities to account for the relative component priorities. We compared HLA-mismatched unrelated donors, haploidentical donors and cord blood using both the hazard ratio (HR) of GRFS and the win ratio related to GRFS. The haploidentical donor group had a similar HR of GRFS (HR: 1.01, 95% confidence interval [CI]: 0.85-1.19, p = 0.916) and win ratio (win ratio: 0.86, 95% CI: 0.72-1.02, p = 0.081) to HLA-mismatched unrelated donors. Cord blood transplantation showed similar GRFS compared to HLA-mismatched unrelated donors in the Cox proportional model (HR: 1.14, 95% CI: 0.98-1.32, p = 0.085), significantly lower win ratio (win ratio: 0.80, 95% CI: 0.68-0.93, p = 0.004) and similar outcomes to haploidentical donors. HLA-mismatched unrelated donor transplantation showed comparable to superior outcomes among alternative donor types. Our results indicate the need to present the win ratio alongside conventional methods to assess the end-point robustly.

Previous studies have shown that the pre-transplant C-reactive protein (CRP)/platelet ratio (CP ratio) is a predictor of survival. The aim of this multicenter retrospective study was to evaluate the clinical significance of CP ratio in patients with malignant lymphoma (ML) who underwent allogeneic hematopoietic stem cell transplantation (alloHCT). The cohort included patients with ML who underwent first alloHCT from 2007 to 2021. CP ratio was defined as CRP [mg/dL]/platelet [104/μL] and evaluated prior to alloHCT. The cutoff value for CP ratio was set at 0.05 based on previous studies. A total of 311 cases were analyzed, of which 134 were mature B cell lymphoma, 177 were T/NK cell lymphoma (including 70 cases of adult T-cell leukemia/lymphoma), and 17 were Hodgkin's lymphoma. The median age was 53 years (range: 17-69 years). High CP ratio was associated with status of disease, presence of infections, poor performance status at alloHCT, and high transfusion volume received prior to alloHCT. Overall survival (OS) at 2 years according to CP ratio (low vs. high) was 61.1% versus 30.1% (p < 0.001), non-relapse mortality (NRM) was 21.4% versus 40.7% (p = 0.001), and the relapse rate was 23.7% versus 32.6% (p = 0.061), respectively. In multivariate analysis, the high CP ratio group was associated with poor OS (HR = 2.20, 95% CI: 1.61-3.02, p < 0.001) and higher NRM (HR = 1.90, 95% CI: 1.28-2.81, p = 0.0014). High CP ratio was found to be associated with poor post-transplant OS and NRM, and was a suitable prognostic biomarker for stratifying the risk of patients with ML who are candidates for alloHCT.

Although allogeneic hematopoietic stem cell transplantation (allo-HCT) is considered a potentially curative therapy for multiple myeloma, disease progression after allo-HCT remains a major limitation. Post-transplant maintenance therapy may help reduce the risk of relapse. Lenalidomide, an immunomodulatory agent, has demonstrated efficacy in multiple myeloma, but its use after allo-HCT is limited due to concerns regarding graft-versus-host disease (GVHD). To evaluate the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of lenalidomide when used as maintenance therapy after allo-HCT for multiple myeloma. This was a prospective, multicenter, phase I/II clinical trial conducted from 2014 to 2019. Lenalidomide maintenance therapy was initiated 100-365 days post-allo-HCT. Eligible patients received lenalidomide on days 1-21 of a 28-day cycle for at least four cycles, beginning at 5 mg/day. A standard 3 + 3 dose-escalation design (Fibonacci method) was used to determine DLT and MTD. The study included 10 patients; one was excluded due to early disease progression, leaving nine patients evaluable for toxicity. The phase II portion was not conducted due to expiration of the trial period. The median interval from allo-HCT to initiation of lenalidomide was 244 days (range, 169-330 days). At the 10 mg/day dose level, one patient experienced moderate chronic GVHD meeting the predefined criteria for DLT. No other DLTs occurred, establishing the MTD at 10 mg/day. No acute GVHD was observed. Two additional patients developed mild chronic GVHD, which resolved spontaneously without treatment. The 2-year progression-free survival (PFS) and overall survival (OS) rates from the start of maintenance therapy were 53% and 78%, respectively. Late initiation of lenalidomide maintenance therapy after allo-HCT for multiple myeloma was feasible at a dose of 10 mg/day and was associated with a low incidence of GVHD-related complications. However, further studies are required to confirm treatment efficacy.

Primary refractory acute myeloid leukaemia (AML) remains a major clinical challenge, with poor outcomes despite salvage chemotherapy. Allogeneic haematopoietic cell transplantation (HCT) continues to be a potentially curative option for these patients. However, recent data on outcomes and prognostic factors specific to primary refractory AML remain limited. We conducted a retrospective analysis of 2600 adult patients with primary refractory AML who underwent their first allogeneic HCT between 2013 and 2022, using data from the Japanese national registry. The 3-year overall survival (OS) and leukaemia-free survival (LFS) rates were 28.5% and 24.4% respectively. The multivariate analysis identified older age (≥50 years), poor performance status (≥2), adverse cytogenetics, extramedullary disease at diagnosis and higher peripheral blood blast count at HCT (≥10%) as significant risk factors for worse OS and LFS. The cumulative incidences of relapse and non-relapse mortality at 3 years were 49.8% and 25.8% respectively. Based on the five significant risk factors, we developed a scoring system that effectively stratified patients into distinct prognostic groups for OS and LFS. This nationwide analysis demonstrated that allogeneic HCT offers the potential for long-term survival in adult patients with primary refractory AML. The proposed risk-scoring system may support clinical decision-making and patient counselling.

High-dose chemotherapy with autologous stem cell transplantation (ASCT) is an option for patients aged ≥ 65 years with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL). Few data are available to select patients suitable for chimeric antigen receptor T-cell (CAR-T) therapy or bispecific antibodies. We retrospectively analyzed the risk factors for poor outcomes for 451 Japanese patients aged ≥ 65 years with R/R DLBCL who received ASCT at either second complete remission or first partial remission (n = 336 and 115, respectively) between 2011 and 2022. CAR-T became commercially available in Japan in March 2019, and the annual number of ASCTs for older patients with R/R DLBCL increased significantly until 2018. However, the number of ASCT cases plateaued in 2018. Multivariate Cox regression analysis identified ≤ 24 months from diagnosis to ASCT (hazard ratio [HR], 1.497) and performance status > 0 at ASCT (HR, 1.460) as independent predictors of overall survival (OS) and an association with late recurrence. The 3-year OS rates were 73.4% (95% confidence interval [CI], 65.8%-79.6%) in patients with > 24 months from diagnosis to ASCT and 58.6% (95% CI, 51.2%-65.2%) in those with ≤ 24 months from diagnosis to ASCT. The 3-year OS rates were 69.4% (95% CI, 62.5%-75.2%) in patients with performance status (PS) = 0 and 60.6% (95% CI, 62.5%-70.4%) in those with PS > 0. CAR-T therapy or bispecific antibodies may be used initially instead of ASCT for early relapsed and refractory patients. However, ASCT remains beneficial for older chemo-sensitive patients with late recurrence and good performance status.

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.

It is uncertain whether FLU/BU4 regimens, classified as myeloablative conditioning (MAC), improve prognosis compared to conventional MAC regimens (conv-MAC) such as CY/TBI and BU/CY. We compared FLU/BU4 with conv-MAC among 6551 patients (FLU/BU4 905, conv-MAC 5646), including acute myeloid leukemia (AML) patients aged 16-59 who received a first allogeneic transplantation from the Japanese nationwide registry. The primary endpoint was overall survival (OS), while secondary endpoints were treatment-related mortality (TRM) and relapse at 3 years. Results indicated comparable OS for conv-MAC regimens among the entire cohort (3-year OS: FLU/BU4 50.4% vs. conv-MAC 55.4%, p < 0.001). Subgroup analysis focusing on elderly patients (aged 50-59) indicated that FLU/BU4 showed a statistically significant improvement in OS (47.0% vs. 42.8%, p = 0.036). Notably, for patients in this cohort transplanted at complete remission (CR), FLU/BU4 demonstrated a substantial advantage over conv-MAC with superior OS (HR 0.75, p = 0.046), lower TRM (HR 0.66, p = 0.035), and comparable relapse (HR 0.84, p = 0.390). These benefits were not observed in elderly patients transplanted at non-CR or in other age groups. In summary, our findings suggest that FLU/BU4 regimen, rather than conv-MAC, may be preferable in MAC-tolerant AML patients, aged 50-59 at CR status. This treatment improves survival by reducing TRM without increasing relapse risk.

In recent years, there have been notable advancements in the treatment of malignant lymphoma. However, a certain percentage of patients are unlikely to achieve a cure through chemotherapy alone. Therefore, allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains a crucial curative treatment for malignant lymphoma. FluBu4, comprising fludarabine (Flu) combined with a myeloablative dose of intravenous busulfan (Bu; 12.8 mg/kg in total), is a widely used conditioning regimen for allo-HSCT, but its usefulness in malignant lymphoma (ML) has not been fully investigated. The objective of this study was to evaluate the efficacy and safety of FluBu4 in allo-HSCT for lymphoma by comparing the outcomes of two conditioning regimens: FluBu4 and FluMel140. We used a Japanese national database from the Transplant Registry Unified Management Program to retrospectively analyze the first allo-HSCT for ML in patients aged ≥16 years. Allo-HSCT cases treated with posttransplant cyclophosphamide were excluded. Two groups, namely FluBu4 and FluMel140 were selected by propensity score matching (PSM) with a case ratio of 1:2. From 921 cases, 113 were selected by PSM for the FluBu4 group and 226 for the FluMel140 group. The median age was 54 (19 to 68) years, the median observation period of survivors was 33.8 months, and 145 (42.7%) had a history of autologous HSCT. There were no significant differences in patients' backgrounds between the two groups after PSM. Three-year overall survival (OS) was significantly worse for FluBu4 than for FluMel140 (28.0% versus 48.6%; P < .01). The 3-year cumulative relapse rate was comparable for FluBu4 and FluMel140 (40.1% versus 38.5%; P = .65). However, 3-year nonrelapse mortality was significantly higher for FluBu4 than for FluMel140 (35.3% versus 22.5%; P = .02). There was no significant difference between the two treatment groups in the cumulative incidence of acute graft-versus-host disease (aGVHD) at day 100 after allo-HSCT and the 3-year cumulative incidence of chronic GVHD. While the common and major cause of death was the relapse of lymphoma, aGVHD, and noninfectious lung complications were observed more frequently with FluBu4 than with FluMel140. One-year cumulative incidence of interstitial pneumonia was significantly higher for FluBu4 than for FluMel140 (5.3% versus 0.4%; P = .03). FluBu4 use was associated with worse nonrelapse mortality (NRM) and OS in allo-HSCT for ML compared with FluBu4 and FluMel140 adjusted by PSM. Patients treated with FluBu4 had a higher incidence of noninfectious pulmonary complications and an increased number of associated deaths. A higher rate of NRM in the patients treated with FluBu4 was particularly evident in patients aged ≥60, and its use should be avoided in this patient population.

Fludarabine and myeloablative busulfan (FluBu4) in allogeneic hematopoietic stem cell transplantation (HSCT) for older people have not been adequately examined. This retrospective study analyzed data from a large-scale, nationwide database in Japan. Adult patients (> 15 years old, y/o) who received their first HSCT with FluBu4 for hematological malignancies were included. They were categorized into the younger (< 60 y/o, N = 1295) and the older group (≥ 60 y/o, N = 993). The 3-year overall survival (OS) rate after HSCT was significantly worse in the older group than in the other (p < 0.01, 39.9% vs. 48.5%). The 3-year non-relapse mortality (NRM) was significantly higher in the older group than in the other (p < 0.01, 30.9% vs. 23.0%), and the 3-year cumulative incidence of relapse was comparable between them. According to the multivariate analysis, age ≥ 60 years was significantly associated with poor OS and high NRM. In a subgroup analysis of the older group, the use of additional chemotherapeutic drugs to FluBu4 was significantly associated with poor OS and high NRM. Total body irradiation was significantly associated with high NRM and 1-year incidence of sinusoidal obstruction syndrome but not with OS. Thus, FluBu4 should be used with caution in older people.

Although the hematopoietic cell transplantation (HCT)-comorbidity index (HCT-CI) score is associated with an increased risk of mortality after allogeneic HCT, it remains unclear how pre-HCT liver dysfunction affects clinical outcomes. We retrospectively compared clinical HCT outcomes among four groups stratified according to the presence of HCT-CI liver and other organ scores, using a Japan transplant registry database between 2010 and 2020. Of the 14235 recipients, 1527 tested positive for an HCT-CI liver score including HBV or HCV hepatitis (n = 503). The 5-year overall survival (OS) was significantly lower in the HCT-CI liver(+) other(+) and HCT-CI liver(-) other(+) groups compared to the HCT-CI liver(+) other(-) and HCT-CI liver(-) other(-) groups [49.9% vs. 59% vs. 66.5% vs. 68.3%, p < 0.001]. A multivariate analysis showed that both the HCT-CI liver(+) other(+) [HR 1.62, p < 0.001] and HCT-CI liver(-) other(+) groups [HR 1.21, p < 0.001] were significantly associated with inferior OS. Similarly, both the HCT-CI liver(+) other(+) [HR 1.89, p < 0.001] and liver(-) other(+) groups [HR 1.26, p < 0.001] were significantly associated with an increased risk of NRM. On the other hand, the HCT-CI liver(+) other(-) group was not associated with either OS or NRM. Separately analyzing the subcohorts with or without HCT-CI other scores, the presence of an HCT-CI liver score alone did not affect survival, while the co-presence of pretransplant liver dysfunction seemed to synergistically increase the adverse impact on OS and NRM among recipients with other organ comorbidities. Further studies will be needed to identify optimal strategies for recipients with pretransplant liver dysfunction.

Influenza virus infections (IVIs) are an important cause of complications and death in immunocompromised patients, but the incidence and risk factors for IVIs in hematological diseases including benign diseases are not fully understood. We retrospectively investigated IVIs in patients with hematological diseases who visited our hematology outpatient department between 2012 and 2019. In 4,864 outpatients, 81(1.67%) IVIs were identified. The incidence of IVIs was 4.82 (95% confidence interval [CI], 3.85-5.96) per 1,000 person-years, with significantly higher rates in post-allogeneic transplant patients (21.0, 95% CI, 12.8-32.5). Progression to lower respiratory tract infection (LRTI) was observed in 7 (8.6%) of 81 patients with IVIs. In a univariate logistic regression analysis, LTRI was associated with age ≥60 years and moderate to severe chronic GVHD. Patients after hematopoietic stem cell transplantation may be at a higher risk for IVIs. Advanced age exacerbated the effects of IVIs on hematological diseases.