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In HLA haploidentical stem cell transplantation, patients and donors usually share one HLA haplotype and have one different HLA haplotype (hetero-to-hetero). However, there are rare cases of transplantation from HLA homozygous donors to heterozygous recipients (homo-to-hetero), resulting in mismatches only in the graft-versus-host direction. We previously reported that homo-to-hetero transplants have a lower survival rate in a mouse model than hetero-to-hetero transplants due to stronger graft-versus-host disease (GVHD) but inferior graft-versus-leukemia effect. To examine whether homo-to-hetero transplant effects also occur in humans, we retrospectively compared the results of 59 homo-to-hetero and 4,539 hetero-to-hetero cases in the Japanese transplant registry data. The results showed no statistical difference between the homo-to-hetero and hetero-to-hetero groups in the cumulative incidences of neutrophil engraftment (83.1% vs 89.0%), acute GVHD II–IV (36.8% vs 38.8%), III–IV (16.8% vs 17.4%), chronic GVHD (32.7% vs 30.7%), relapse (52.9% vs 49.0%), and non-relapse mortality (31.6% vs 28.2%). In contrast, overall survival was significantly lower in the homo-to-hetero group than in the hetero-to-hetero group (12.6% vs 26.2%, p = 0.0308). The inferior effect of homo-to-hetero transplantation on overall survival remained significant in multivariate analyses. [ABSTRACT FROM AUTHOR]

Cytomegalovirus (CMV) infection is a major infectious complication following allogeneic hematopoietic cell transplantation (allo-HCT). Although letermovir (LMV) prophylaxis dramatically reduces the incidence of early clinically significant CMV (csCMV) infection, it remains unclear whether it has a beneficial effect on nonrelapse mortality (NRM) and overall survival (OS). Herein, we evaluated the impact of LMV prophylaxis on posttransplant outcomes using the registry database of the Japanese Society for Transplantation and Cellular Therapy. Adult patients who underwent allo-HCT between 2017 and 2019 were analyzed (n = 6004). LMV prophylaxis was administered to 1640 patients (LMV group) and it significantly reduced the incidence of csCMV infection compared with those not administered LMV prophylaxis (15.4% vs 54.1%; p < 0.01). However, it did not improve the 1-year NRM (hazard ratio [HR], 0.93; p = 0.40) and OS (HR, 0.96; p = 0.49). In the LMV group, 74 patients had breakthrough csCMV infection and showed inferior NRM (HR, 3.44; p < 0.01) and OS (HR, 1.93; p = 0.02) compared with those without infection. After completing LMV prophylaxis, 252 patients had late csCMV infection and showed inferior NRM (HR, 1.83; p < 0.01) and OS (HR, 1.58; p < 0.01). Our findings suggest that managing breakthrough and late csCMV infections is important for improving long-term outcomes. [ABSTRACT FROM AUTHOR]

Stenotrophomonas maltophilia (S. maltophilia) is an aerobic nonfermenting Gram-negative bacillus widely distributed in the environment that has inherent multidrug resistance to beta-lactam and carbapenem antibiotics. S. maltophilia infection (SMI) is known as an important fatal complication following allogeneic hematopoietic stem cell transplantation (HSCT), but its clinical characteristics have not been well clarified. A retrospective study to identify the incidence, risk factors, and outcomes of SMI after allogeneic HSCT was performed using the database of the Japanese nationwide registry, including 29,052 patients who received allogeneic HSCT in Japan between January 2007 and December 2016. A total of 665 patients developed SMI (sepsis/septic shock, 432; pneumonia, 171; other, 62). The cumulative incidence of SMI at 100 days after HSCT was 2.2%. Among risk factors identified for SMI (age ≥ 50 years, male, performance status 2–4, cord blood transplantation [CBT], myeloablative conditioning, Hematopoietic Cell Transplant-Comorbidity Index [HCT-CI] score 1–2, HCT-CI score ≥ 3, and active infectious disease at HSCT), CBT was the strongest risk factor (hazard ratio, 2.89; 95%CI, 1.94–4.32; p < 0.001). The survival rate at day 30 after SMI was 45.7%, and SMI before neutrophil engraftment was significantly associated with poor survival (survival rate 30 days after SMI, 40.1% and 53.8% in patients with SMI before and after engraftment, respectively; p = 0.002). SMI is rare after allogeneic HSCT, but its prognosis is extremely poor. CBT was a strong risk factor for SMI, and its development prior to neutrophil engraftment was associated with poor survival. [ABSTRACT FROM AUTHOR]

Bone marrow (BM) and granulocyte colony-stimulating factor-mobilized peripheral blood stem cells (PBSC) are used as grafts from HLA-identical-related donors for adults with myelodysplastic syndrome (MDS). To assess the impact of graft sources on post-transplant outcomes in MDS patients, we conducted a retrospective analysis of a nationwide database. A total of 247 and 280 patients underwent transplantation with BM and PBSC, respectively. The inverse probability of treatment weighting (IPTW) methods revealed that overall survival (OS) was comparable between BM and PBSC (P =.129), but PBSC transplantation was associated with worse graft-versus-host disease (GVHD)-free/relapse-free survival (GRFS) (hazard rate [HR], 1.24; 95% confidence intervals [CIs], 1.00–1.53; P = 0.049) and chronic GVHD-free and relapse-free survival (CRFS) (HR, 1.29; 95% CIs, 1.13–1.73; P = 0.002) than BM transplantation. In the propensity score matched cohort (BM, n = 216; PBSC, n = 216), no significant differences were observed in OS and relapse; 3-year OS rates were 64.7% and 60.0% (P = 0.107), while 3-year relapse rates were 27.1% and 23.5% (P = 0.255) in BM and PBSC, respectively. Three-year GRFS rates (36.6% vs. 29.2%; P = 0.006), CRFS rate (37.7% vs. 32.5%; P = 0.003), and non-relapse mortality rates (13.9% vs. 21.1%; P = 0.020) were better in BM than in PBSC. The present study showed that BM transplantation provides a comparable survival benefit with PBSC transplantation and did not identify an enhanced graft-versus-MDS effect to reduce the incidence of relapse in PBSC transplantation. [ABSTRACT FROM AUTHOR]

The coronavirus disease 2019 (COVID-19) pandemic affected healthcare quality and access worldwide and may also have negatively affected the frequency and outcomes of allogeneic hematopoietic stem cell transplantation (HSCT). We evaluated the effect of the pandemic on allogeneic HSCT in Japan. Our subjects were patients who received allogeneic HSCT during January 2018–December 2020 in Japan. We assessed differences in yearly number of allogeneic HSCTs and 1-year outcomes in 2020 versus both 2019 and 2018. The total number of patients who received allogeneic HSCT increased from 3621 patients in 2018 and 3708 patients in 2019 to 3865 patients in 2020. Some following changes in allogeneic HSCT methods were observed: patients were older, fewer patients received bone marrow transplantation, fewer patients received transplants from unrelated donors, fewer patients received transplants from matched donors, more patients received reduced-intensity conditioning, and fewer patients received anti-thymocyte globulin in 2020 compared with previous years. HSCT outcomes were not affected, as 1-year overall survival was not significantly different (65.8% in 2020, vs. 66.5% in 2019 and 66.4% in 2018). Our results suggest that we can maintain transplant care during the pandemic by controlling the spread of COVID-19 and modifying HSCT methods. [ABSTRACT FROM AUTHOR]

The incidence of severe adverse events (SAEs) and associated risk factors in hematopoietic cell transplantation donors needs to be clarified for related donors (relatives of the transplant recipient), whose criteria for donation are more lenient than for unrelated donors. Data from related donors registered in the Japanese national data registry database between 2005 and 2021 were evaluated to determine the association of short-term SAE incidence with donor characteristics at registration. Fourteen of 4339 bone marrow (BM) donors (0.32%) and 54 of 10,684 peripheral blood stem cell (PBSC) donors (0.51%) experienced confirmed SAEs during the short donation period. No deaths were observed. Past medical history was a common risk factor for SAEs in both BM and PBSC donors. Age of 60 years or older and female sex were identified as risk factors for SAEs in PBSC donors. Female sex was also a risk factor for poor mobilization, which resulted in discontinuation of PBSC collection. Although donors should be selected carefully, a certain level of safety is ensured for related donors in Japan. Donor safety should be further increased by improving the selection method for related donors and extending the follow-up period. [ABSTRACT FROM AUTHOR]

Allogeneic hematopoietic cell transplantation (HCT) offers a possible cure for patients with relapsed and refractory non-Hodgkin lymphoma (NHL) through potentially beneficial graft versus lymphoma effects. However, allogeneic HCT is associated with high nonrelapse mortality (NRM). Fludarabine with reduced-intensity busulfan (Flu/Bu2) and myeloablative busulfan (Flu/Bu4) are commonly used in conditioning regimens for allogeneic HCT; however, data on their use in patients with NHL is limited. We investigated the effect of busulfan dose on outcomes by comparing Flu/Bu2 and Flu/Bu4 in patients with NHL who underwent allogeneic HCT. Our study included 415 adult patients with NHL who received Flu/Bu2 (315 patients) or Flu/Bu4 (100 patients) between January 2008 and December 2019. All patients were enrolled in the Transplant Registry Unified Management Program 2 of the Japanese Data Center for Hematopoietic Cell Transplantation. The primary endpoint was the 5-year overall survival (OS). To minimize potential confounding factors that may influence outcomes, we performed propensity score matching. The 5-year OS was 50.6% (95% confidence interval (CI), 39.4%–60.8%) and 32.2% (95% CI, 22.4–42.4%) in the Flu/Bu2 and Flu/Bu4 groups, respectively (p = 0.006). The hazard ratio comparing the two groups was 2.13 (95% CI, 1.30–3.50; p = 0.003). Both groups had a similar 5-year cumulative incidence of relapse (38.2% vs 41.3%; p = 0.581), and the Flu/Bu4 group had a higher cumulative incidence of 5-year NRM (15.7% vs 31.9%; p = 0.043). In this study, Flu/Bu4 was associated with worse OS compared with Flu/Bu2 because of high NRM in patients with NHL. [ABSTRACT FROM AUTHOR]

Antithymocyte globulin (ATG) reduces severe acute and chronic graft-versus-host disease (GVHD) in allogeneic peripheral blood stem cell transplantation (PBSCT). However, risk factors for severe acute GVHD in PBSCT using ATG remain to be determined. We conducted a single-center, retrospective study to analyze the association of acute GVHD requiring systemic corticosteroid (SC-aGVHD) with absolute lymphocyte counts (ALC) before the administration of ATG or conditioning in 53 patients with HLA-matched PBSCT using low-dose thymoglobulin (2 mg/kg) after myeloablative conditioning. The cumulative incidence of SC-aGVHD was 17.0% and ALC before ATG were significantly higher in patients with SC-aGVHD compared to that in patients without it (median, 0.15 × 109/L vs 0.06 × 109/L, P = 0.047). The cumulative incidence of SC-aGVHD was significantly higher in patients with high ALC before ATG (≥ 0.15 × 109/L) than in those with low ALC (38.5% vs 10.0%, P = 0.016). Non-relapse mortality (NRM) was also significantly higher in the high ALC before ATG group than the low ALC before ATG group (2-year NRM: 23.9% vs 6.0%, P = 0.048), leading to worse survival (2-year overall survival: 69.2% vs 83.5%, P = 0.039). Our study suggested that high ALC before ATG is a risk factor for SC-aGVHD. [ABSTRACT FROM AUTHOR]

Lenalidomide (Len) and dexamethasone (dex) therapy is a standard therapy in patients with multiple myeloma. Elderly or unfit patients may reduce Len or dex doses to prevent toxicities that lead to treatment discontinuation. However, there have been few studies evaluating the efficacy and safety of lower doses of Len and dex. We conducted a phase II study of 1.5-year low-dose Len and dex therapy following melphalan and prednisolone (MP), the number of which cycles was determined by a response within 9 cycles. The Len dose was 10 mg daily and the dex dose was 20 mg weekly, which were continued for 1.5 years. Twenty-one patients were enrolled. The median number of cycles of MP was 3 (range, 2-9). The overall response rate was 81% and a very good partial response or better was achieved in 33.3% of patients. The median follow-up time for survivors was 70.5 months (range, 42-83 months), the median progression-free survival (PFS) was 27 months (95% CI, 21-33 months), and the median overall survival was not reached. Grade 3 or 4 adverse events were observed in 28.6% of patients. In conclusion, the low-dose Len and dex therapy safely achieved comparable efficacies to the standard-dose regimen in elderly patients with newly diagnosed multiple myeloma. UMIN000007889. [ABSTRACT FROM AUTHOR]

Although a combination of calcineurin inhibitor and methotrexate (MTX) is used for graft-versus-host disease (GVHD) prophylaxis in umbilical cord blood transplantation (CBT), optimal dose of MTX for CBT remains to be determined. We conducted a retrospective study to evaluate the safety and efficacy of standard-dose MTX (St-MTX, 15 mg/m2 on day 1 and 10 mg/m2 on days 3 and 6) and mini-dose MTX (Mini-MTX, 5 mg/m2 on days 1, 3 and 6) for GVHD prophylaxis in patients who underwent single unit CBT against hematological malignancies. Thirty-two and 26 patients received St-MTX and Mini-MTX, respectively. Cumulative incidence of neutrophil engraftment was significantly higher in the Mini-MTX group than in the St-MTX group (88.5% vs 65.6%, P = 0.00448). Cumulative incidences of grade II to IV and grade III to IV of acute graft-versus-host disease (GVHD) were 34.4% and 6.2% in the St-MTX group, and 34.6% and 7.7% in the Mini-MTX group with no statistical significance. One-year non-relapse mortality (NRM) was significantly lower in the Mini-MTX group compared to the St-MTX group (31.2% vs 3.8%, P = 0.00938), whereas relapse rate was not different between the groups. Multivariate analysis also indicated that Mini-MTX significantly improved engraftment (HR, 0.5359; 95% CI, 0.3082 to 0.9318; P = 0.0270) and reduced NRM (HR, 0.117; 95% CI, 0.0151 to 0.9067; P = 0.040). Our study suggests that GVHD prophylaxis using Mini-MTX in CBT is feasible and associated with improvement of engraftment and reduction in NRM. [ABSTRACT FROM AUTHOR]