Impact of donor type on the outcomes of acute graft versus host disease to systemic corticosteroid therapy.

Systemic corticosteroid therapy is a well-established first-line treatment for grades II-IV acute graft-versus-host disease (aGVHD). Recently, several developments have occurred, including the introduction of transplantation from human leukocyte antigen (HLA) haploidentical donors using post-transplant cyclophosphamide (PTCY-Haplo), and improvements in prognosis after cord blood transplantation (CBT) in Japan. This study aimed to analyze the association between donor sources and outcomes in patients with aGVHD. Our study included 2732 patients who developed grades II-IV aGVHD, and were treated with systemic corticosteroids. We compared HLA-matched related donors (MRD), HLA-matched unrelated donors (MUD), PTCY-Haplo, and CBT. We set endpoint as response rate, 1-year cumulative incidence of non-relapse mortality (NRM), and overall survival (OS). The adjusted odds ratios for a complete response (CR) were 0.99 (95% confidence interval [CI]: 0.74-1.31, P = 0.925) for MUD, 2.08 (95% CI: 1.35-3.25, P = 0.001) for PTCY-Haplo, and 1.08 (95% CI: 0.83-1.41, P = 0.550) for CBT compared with MRD. A significant increase in response rates for PTCY were only found in a single-organ involvement. No significant association was observed between the donor source and NRM or OS. In conclusion, PTCY-Haplo is associated with a high response rate in patients with a single-organ aGVHD; however, MUD and CBT were not associated with treatment response.

Haploidentical transplantation with post-transplant cyclophosphamide versus single cord blood transplantation in adults with relapsed/refractory non-Hodgkin lymphoma.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment for relapsed or refractory non-Hodgkin lymphoma (R/R NHL). Allo-HSCT using post-transplant cyclophosphamide (PTCY-haplo) and umbilical cord blood transplantation (uCBT) are important donor options in the absence of matched related siblings. However, the data comparing these two donor sources in R/R NHL are limited. Using the Japanese nationwide transplantation registry data, we identified 857 patients with R/R NHL, including 169 patients who received PTCY-haplo and 688 who received uCBT for their first allo-HSCT between January 2013 and December 2021; 514 patients (60%) had B-cell lymphoma. More PTCY-haplo recipients received allo-HSCT using a reduced-intensity conditioning regimen in recent years. The 3-year overall survival (OS), progression-free survival (PFS), and graft-versus-host disease (GVHD)-free/relapse-free survival (GRFS) rates in the PTCY-haplo and uCBT groups were 44% versus 39% (P = 0.326), 34% versus 33% (P = 0.660), and 19% versus 23% (P = 0.910), respectively; the adjusted hazard ratios for OS, PFS, and GRFS were 0.89 (95% confidence interval: 0.69-1.15, P = 0.373), 0.98 (0.78-1.22, P = 0.852), and 0.92 (0.83-1.21, P = 0.920), respectively. The PTCY-haplo group showed faster neutrophil and platelet engraftment and a lower incidence of grade III-IV acute GVHD. Thus, PTCY-haplo and uCBT could serve as alternative donor sources in patients with R/R NHL.

Complete detection of FR1 to FR3 primer-based PCR patterns of immunoglobulin heavy chain rearrangement in the BIOMED-2 protocol is associated with poor prognosis in patients with diffuse large B-cell lymphoma.

Somatic hypermutations (SHMs) in the variable region (VH) of the immunoglobulin heavy chain (IgH) gene are common in diffuse large B-cell lymphoma (DLBCL). Recently, IgH VH SHMs have become known as immunogenic neoantigens, but few studies have evaluated the prognostic impact of the frequency of VH SHMs in DLBCL. The BIOMED-2 protocol is the gold standard polymerase chain reaction (PCR) for clonality analysis in lymphoid malignancies, but can produce false negatives due to the presence of IgH VH SHMs. To overcome this problem, three primer sets were designed for the three framework regions (FR1, FR2, and FR3). We evaluated the predictive value of this PCR pattern in patients with DLBCL. To evaluate the prognostic impact of complete detection of the clonal amplifications (VHFR1-JH, VHFR2-JH, and VHFR3-JH) in the BIOMED-2 protocol, we retrospectively analyzed 301 DLBCL patients who were initially treated with anthracycline-based immunochemotherapy. Complete detection of the FR1 to FR3 primer-based IgH VH PCR patterns in the BIOMED-2 protocol was associated with low frequency of VH SHMs (p < 0.001). Patients who were positive for all these three PCRs (n = 79) were significantly associated with shorter 5-year overall survival (OS; 54.2% vs. 73.2%; p = 0.002) and progression-free survival (PFS; 34.3% vs. 59.3%; p < 0.001) compared to patients with other PCR patterns (n = 202). Specifically, the successful FR3-JH detection was associated with significantly worse OS (p < 0.001) and PFS (p < 0.001). PCR patterns of complete IgH rearrangement using the BIOMED-2 protocol are clinically meaningful indicators for prognostic stratification of DLBCL patients.

Reduced-intensity conditioning with fludarabine/busulfan versus fludarabine/low-dose melphalan in patients with non-Hodgkin lymphoma undergoing allogeneic haematopoietic stem cell transplantation.

Reduced-intensity conditioning regimens are commonly used in allogeneic haematopoietic cell transplantation for non-Hodgkin lymphoma (NHL); however, the optimal regimen remains unknown. In this study, the outcomes of adult patients with NHL who received fludarabine plus reduced-dose busulfan (6.4 mg/kg; Flu/Bu2) (n = 286) and fludarabine plus low-dose melphalan (80 or 100 mg/m2; Flu/Mel80-100) (n = 283) between January 2009 and December 2020 were compared using Japanese registry data. The primary end-point was the 5-year overall survival (OS). The 5-year OS was 53.8% (95% CI, 47.6-59.6) and 42.4% (95% CI, 35.6-49.0) in the Flu/Bu2 and Flu/Mel80-100 groups respectively (p = 0.030). After inverse probability of treatment weighting adjustment, the adjusted HR of Flu/Bu2 compared with Flu/Mel80-100 group for 5-year OS was 0.77 (95% CI, 0.60-0.99, p = 0.046), 0.97 (95% CI, 0.78-1.21, p = 0.798) for 5-year progression-free survival, 0.65 (95% CI, 0.45-0.94, p = 0.022) for 5-year cumulative risk of non-relapse mortality and 1.25 (95% CI, 0.95-1.64, p = 0.115) for 5-year cumulative risk of relapse. In this study, patients with NHL who received Flu/Bu2 were associated with better OS and lower non-relapse mortality than those who received Flu/Mel80-100.

Effect of peptide-binding motif on survival of HLA-haploidentical transplantation with post-transplant cyclophosphamide.

Peptide-binding motif (PBM) model, a hierarchical clustering of HLA class I based on their binding specificity, was developed to predict immunopeptidome divergence. The effect of PBM mismatches on outcomes is unknown in HLA-haploidentical haematopoietic cell transplantation with post-transplant cyclophosphamide (PTCy-haplo). We therefore conducted a retrospective study using national registry data in PTCy-haplo. Overall, 1352 patients were included in the study. PBM-A bidirectional mismatch was associated with an increased risk of overall mortality in multivariable analysis (hazard ratio, 1.26; 95% confidence interval, 1.06 to 1.50; p = 0.010). None of relapse, non-relapse mortality (NRM) and graft-versus-host disease showed significant differences according to PBM-A bidirectional mismatch status in the entire cohort. The impact of PBM-A bidirectional mismatch on overall survival (OS) was preserved within the HLA-A genotype bidirectional mismatch population, and their lower OS stemmed from higher relapse rate in this population. The worse OS due to high NRM with PBM-A bidirectional mismatch was prominent in lymphoid malignancies receiving reduced-intensity conditioning. The PBM model may predict outcomes more accurately than HLA genotype mismatches. In conclusion, this study demonstrated that the presence of PBM-A bidirectional mismatch elevated the risk of mortality of PTCy-haplo. Avoiding PBM-A bidirectional mismatch might achieve better outcomes in PTCy-haplo.

An open-label study of belumosudil, a selective ROCK2 inhibitor, as second or subsequent line of therapy for steroid-dependent/steroid-resistant chronic GVHD.

Belumosudil mesylate is a selective Rho-associated coiled-coil kinase 2 inhibitor with immunomodulatory and antifibrosis effects. This multicenter, open-label, single-arm study evaluated belumosudil 200 mg once daily as second or subsequent line of therapy (LOT) in 21 Japanese patients ≥12 years of age with steroid-dependent/steroid-resistant chronic graft-versus-host disease (cGVHD). The primary endpoint of best overall response rate (ORR) at 24 weeks after enrollment of the last patient was 85.7% (95% confidence interval [CI]: 63.7-97.0), and the lower limit of the 95% CI exceeded the pre-defined threshold of 25%. The Kaplan-Meier estimate of duration of response rate at 24 weeks was 75% (95% CI: 46-90); 13/18 responders (72.2%) had a sustained response for ≥20 weeks. The median time to response was 4.1 weeks (range 3.90-8.10); ORR was 47.6% at 4 weeks and 75.0% at 24 weeks; best ORR was 80% for joints/fascia, 66.7% for the mouth, and 54.5% for skin. Overall, 57.1% of patients had clinically meaningful symptom improvement at least once; the median duration of symptom improvement was 22.2 weeks (range 4.0-51.3). Corticosteroid dose reductions were recorded for 57.1% of patients. Median failure-free and overall survival were not reached. Treatment-emergent adverse events occurred in 85.7% of patients (most commonly diarrhea, 19.0%), of which 38.1% were drug-related. There were no drug-related discontinuations or deaths. In summary, belumosudil 200 mg once daily as second or subsequent LOT in Japanese patients with steroid-dependent/steroid-resistant cGVHD was effective, with no new safety concerns.

The impact of daratumumab pretreatment on multiple myeloma patients undergoing autologous transplantation.

The anti-CD38 antibody daratumumab (Dara) has been reported to improve the prognosis of multiple myeloma (MM) patients, but its use before autologous stem cell transplantation (ASCT) remains controversial. To clarify the prognostic impact of Dara before ASCT on MM, we performed a retrospective observational analysis. We analyzed 2626 patients who underwent ASCT between 2017 and 2020. In the comparison between patients not administered Dara (Dara- group) and those administered Dara (Dara+ group), the 1-year progression-free survival (PFS) rates were 87.4% and 77.3% and the 1-year overall survival (OS) rates were 96.7% and 90.0%, respectively. In multivariate analysis, age <65 years (p = 0.015), low international staging system (ISS) stage (p < 0.001), absence of unfavorable cytogenic abnormalities (p < 0.001), no Dara use before ASCT (p = 0.037), and good treatment response before ASCT (p < 0.001) were independently associated with superior PFS. In matched pair analysis, the PFS/OS of the Dara- group were also significantly superior. For MM patients who achieved complete or very good partial response (CR/VGPR) by Dara addition before ASCT, both PFS and OS significantly improved. However, in patients who did not achieve CR/VGPR before ASCT, the PFS/OS of the Dara+ group were significantly inferior to those of the Dara- group.

Significance of absolute neutrophil count before allogeneic hematopoietic stem cell transplantation in adult patients with aplastic anemia.

The impact of absolute neutrophil count (ANC) before allogenic hematopoietic stem cell transplantation (HSCT) on the outcomes for patients with aplastic anemia (AA) remains unclear. We retrospectively evaluated the relationship between ANC before transplantation and patient outcomes, involving 883 adult Japanese patients with AA who underwent allogeneic HSCT as their first transplantation between 2008 and 2020. Patients were divided into three groups based on ANC: 0/µL (n = 116); 1-199 (n = 210); and ≥ 200 (n = 557). In the low ANC groups (ANC < 200), patient age was higher, previous anti-thymocyte globulin (ATG) treatments were infrequent, duration from diagnosis to transplantation was shorter, hematopoietic cell transplantation-comorbidity index (HCT-CI) was higher, ATG-based conditioning was used infrequently, and peripheral blood stem cell from related donor and cord blood were used frequently. In multivariate analysis, patient age, previous ATG treatment, HCT-CI, stem cell source, and ANC before transplantation were significantly associated with 5-year overall survival (OS) ("ANC ≥ 200": 80.3% vs. "ANC 1-199": 71.7% vs. "ANC 0": 64.4%). The cumulative incidence of bacterial infection, invasive fungal disease, and early death before engraftment were significantly higher in the low ANC groups. Among patients with ANC of zero before transplantation, younger patient age, shorter duration from diagnosis to transplantation, HCT-CI of 0, and bone marrow from related donor as stem cell source were significantly associated with better OS. Consequently, ANC before allogeneic HSCT was found to be a significant prognostic factor in adult patients with AA. Physicians should pay attention to ANC before transplantation.

Successful maintenance treatment of disseminated nocardiosis with cerebral abscess in a severely immunocompromised patient allergic to trimethoprim-sulfamethoxazole using moxifloxacin and high-dose minocycline: A case report.

Nocardiosis in patients after allogeneic hematopoietic stem cell transplantation (HSCT) is rare, but is associated with a significant mortality risk. Although trimethoprim-sulfamethoxazole (TMP/SMX) remains the cornerstone of nocardiosis treatment, optimal alternative therapies for patients intolerant to TMP/SMX are not well-established. Herein, we report a case of disseminated nocardiosis with bacteremia and multiple lesions in the lungs and brain caused by Nocardia farcinica, in a 60-year-old man who had previously undergone allogeneic HSCT and was receiving immunosuppressants for severe chronic graft-versus-host disease. The patient received atovaquone for the prophylaxis of Pneumocystis pneumonia because of a previous serious allergic reaction to TMP/SMX. The patient was initially treated with imipenem/cilastatin and amikacin, which were later switched to ceftriaxone and amikacin based on the results of antimicrobial susceptibility testing. After switching to oral levofloxacin and a standard dose of minocycline, the patient experienced a single recurrence of brain abscesses. However, after switching to oral moxifloxacin and high-dose minocycline, the patient did not experience any relapses during the subsequent two years and seven months of treatment. In treating nocardiosis with brain abscesses, it is crucial to select oral antibiotics based on the antimicrobial susceptibility test results and pharmacokinetics, especially when TMP/SMX is contraindicated. A combination of oral moxifloxacin and high-dose minocycline could be a promising alternative therapy.

Allogeneic transplantation of bone marrow versus peripheral blood stem cells from HLA-identical sibling donors for hematological malignancies in 6064 adults from 2003 to 2020: different impacts on survival according to time period.

BACKGROUND: Mobilized peripheral blood stem cells (PBSC) have been widely used instead of bone marrow (BM) as the graft source for allogeneic hematopoietic cell transplantation (HCT). Although early studies demonstrated no significant differences in survival between PBSC transplantation (PBSCT) and BM transplantation (BMT) from human leukocyte antigen (HLA)-identical sibling donors to adults with hematological malignancies, recent results have been unclear. OBJECTIVE: The objective of this retrospective study was to compare overall survival (OS), relapse, non-relapse mortality (NRM), hematopoietic recovery and graft-versus-host disease (GVHD) between PBSCT and BMT according to the time period of HCT (2003-2008, 2009-2014, or 2015-2020). STUDY DESIGN: We retrospectively compared the outcomes after PBSCT versus BMT in 6064 adults with hematological malignancies using a Japanese registry database between 2003 and 2020. RESULTS: The adjusted probability of OS was significantly higher in BMT recipients compared to PBSCT recipients during the early period of 2003-2008 (adjusted hazard ratio [HR], 0.79; 95% confidence interval [CI], 0.70-0.91; P < 0.001) and the middle period of 2009-2014 (adjusted HR, 0.80; 95% CI, 0.70-0.91; P < 0.001). However, during the late period of 2015-2020, the adjusted probability of OS was comparable between BMT and PBSCT recipients (adjusted HR, 0.94; 95% CI, 0.79-1.13; P = 0.564), which were mainly due to the reduction of NRM. There was no significant difference in the relapse rate between the groups, irrespective of the time period. Compared to BMT, PBSCT led to faster neutrophil and platelet recovery and the cumulative incidences of grades II-IV and grades III-IV acute and overall and extensive chronic GVHD were significantly higher in PBSCT recipients, irrespective of the time period. CONCLUSIONS: PBSCT and BMT had similar survival outcomes and relapse rates in adult patients with hematological malignancies during the late time period of 2015-2020 despite the hematopoietic recovery and acute and chronic GVHD being higher in PBSCT recipients in all time periods.

First complete remission favours haploidentical haematopoietic stem cell transplantation with post-transplant cyclophosphamide over cord blood transplantation in acute lymphoblastic leukaemia.

To assess the benefits of HLA-haploidentical haematopoietic stem cell transplantation using post-transplant cyclophosphamide (PTCy-haplo) relative to those of umbilical cord blood (UCB) transplantation in acute lymphoblastic leukaemia (ALL), we analysed 1999 patients (PTCy-haplo, 330; UCB, 1669), using the nationwide Japanese registry. PTCy-haplo was associated with a significantly higher relapse rate, but lower non-relapse mortality, which results in overall survival and disease-free survival, comparable to those of UCB. Among patients in CR1, PTCy-haplo showed a significantly higher survival than UCB regardless of the CD34+ cell dose. Our findings provide valuable insights into the donor selection algorithm in allogeneic HSCT for adult patients with ALL.

Peripheral blood stem cell transplantation using HLA-haploidentical donor with post-transplant cyclophosphamide versus HLA-matched sibling donor for lymphoma.

Data comparing HLA-haploidentical donors and HLA-matched sibling donors (MSDs) in peripheral blood stem cell transplantation (PBSCT) for lymphoma are scarce. We retrospectively analyzed 465 patients with lymphoma aged 16 years or older who underwent PBSCT using haploidentical donors with post-transplant cyclophosphamide (PTCy-haplo) (n = 166) or MSDs with calcineurin inhibitor-based graft-versus-host disease (GVHD) prophylaxis (n = 299). Two-year overall survival (OS), progression-free survival (PFS), and GVHD-free, relapse-free survival (GRFS) in the PTCy-haplo and MSD groups were 49.2% versus 51.9% (P = 0.64), 38.0% versus 39.9% (P = 0.97), and 27.7% versus 18.5% (P = 0.006), respectively. In multivariable analyses, PTCy-haplo recipients had slower neutrophil recovery (hazard ratio [HR], 0.62; P < 0.001) and platelet recovery (HR, 0.54; P < 0.001), lower risk of chronic GVHD (HR, 0.64; P = 0.038) and extensive chronic GVHD (HR, 0.45; P = 0.008), and better GRFS (HR, 0.66; P = 0.003) than MSD transplant recipients. OS, PFS, relapse or progression, and non-relapse mortality were similar between the groups. The difference might be mainly due to PTCy use rather than donor type; however, the results suggested that PTCy-haplo could be a possible option as an alternative to conventional MSD transplantation for lymphoma in PBSCT.

Association of individual comorbidities with outcomes in allogeneic hematopoietic cell transplantation from unrelated adult donors versus unrelated cord blood: A study on behalf of the Donor/Source and Transplant Complications Working Groups of the Japanese Society for Transplantation and Cellular Therapy.

We retrospectively evaluated the effect of 17 individual comorbidities, defined by the hematopoietic cell transplantation (HCT)-specific comorbidity index, on non-relapse mortality (NRM) and overall survival (OS) in 9531 patients aged between 16 and 70 years who underwent their first allogeneic HCT from 8/8 and 7/8 allele-matched unrelated donors (8/8 and 7/8 MUDs) or single-unit unrelated cord blood (UCB) between 2011 and 2020 using data from a Japanese registry database. In the multivariate analysis, infection (adjusted hazard ratio [HR], 1.62, 95% confidence interval [CI], 1.33-1.99 for 8/8 and 7/8 MUDs; adjusted HR, 1.33, 95%CI, 1.12-1.58 for UCB) and moderate/severe hepatic comorbidity (adjusted HR, 1.57, 95%CI, 1.04-2.38 for 8/8 and 7/8 MUDs; adjusted HR, 1.53, 95%CI, 1.09-2.15 for UCB) had a significant impact on NRM in both donor groups. Cardiac comorbidity (adjusted HR, 1.40, 95%CI, 1.08-1.80), mild hepatic comorbidity (adjusted HR, 1.22, 95%CI, 1.01-1.48), rheumatologic comorbidity (adjusted HR, 1.67, 95%CI, 1.11-2.51), renal comorbidity (adjusted HR, 2.44, 95%CI, 1.46-4.09), and severe pulmonary comorbidity (adjusted HR, 1.40, 95%CI, 1.11-1.77) were significantly associated with an increased risk of NRM but only in UCB recipients. Renal comorbidity had the strongest impact on poor OS in both donor groups (adjusted HR, 1.73, 95%CI, 1.10-2.72 for 8/8 and 7/8 MUDs; adjusted HR, 2.24, 95%CI, 1.54-3.24 for UCB). Therefore, unrelated donor selection should be taken into consideration along with the presence of specific comorbidities, such as cardiac, rheumatologic, renal, mild hepatic, and severe pulmonary comorbidities.

Effect of graft-versus-host disease on outcomes of HLA-haploidentical peripheral blood transplantation using post-transplant cyclophophamide.

There is limited evidence regarding the association between graft-versus-host disease (GVHD) and reduced relapse in patients who undergo allogeneic hematopoietic stem cell transplantation from haploidentical donors (haplo-HSCT) using post-transplant cyclophosphamide (PTCY). We investigated the association between GVHD and transplant outcomes in 938 patients who received haplo-HSCT using PTCY. Overall survival (OS), relapse rate, and non-relapse mortality (NRM) were evaluated using landmark analysis at the landmark points at 100 and 360 days after HSCT for acute and chronic GVHD, respectively. Grade I-II acute GVHD was not associated with OS (adjusted hazard ratio: 1.15, 95% confidence interval: 0.85-1.57), relapse (1.03, 0.74-1.45) and NRM (1.15, 0.74-1.77). Conversely, grade III-IV acute GVHD was associated with higher NRM (3.16, 1.61-6.19), but no other outcomes. Limited chronic GVHD was not associated with OS (1.11, 0.48-1.95), relapse (1.05, 0.30-3.75) and NRM (1.30, 0.45-3.79). Extensive chronic GVHD was associated with higher NRM (2.40, 1.03-5.57), but no other outcome. In conclusion, any GVHD was not associated with a reduced relapse rate and improved OS, and Grade III-IV acute GVHD and extensive chronic GVHD were associated with higher NRM in patients who received haplo-HSCT using PTCY.

Sequential cellular and humoral responses after repetitive COVID-19 vaccination in patients treated with anti-CD20 antibodies.

Patients treated with anti-CD20 antibodies for haematological disorders have insufficient immune responses to mRNA COVID-19 vaccines; however, relevant sequential data are lacking. We sequentially evaluated the humoral and cellular immune responses in 22 patients who had received anti-CD20 antibodies within 12 months before the first vaccination, before and after the third and fourth vaccinations. Humoral responses improved gradually, along with the resolution of B-cell depletion. A steady increase was noted in cellular responses, regardless of the B-cell status. Our findings suggest the potential benefit of repeated vaccinations in these patients until B-cell recovery is confirmed while enhancing cellular responses.

Effect of Conditioning Regimens and Graft-versus-Host Disease Prophylaxis on the Outcomes of Umbilical Cord Blood Transplantation Performed with Cyclophosphamide/Total Body Irradiation-Based Regimens.

Umbilical cord blood (UCB) is a valuable alternative donor source for allogeneic hematopoietic stem cell transplantation. Various conditioning regimens and graft-versus-host disease (GVHD) prophylaxis regimens aimed at improving the outcomes of umbilical cord blood transplantation (UCBT) have been explored; however, the differences in their effects remain unclear. This study was conducted to elucidate the differences in the effects of conditioning and GVHD prophylaxis regimens on UCBT outcomes by disease type in a nationwide, retrospective study. We retrospectively analyzed the effects of conditioning and GVHD prophylaxis regimens on the outcomes of UCBT performed with cyclophosphamide (Cy)/total body irradiation (TBI)-based regimens in patients with acute myeloid leukemia (AML; n = 1126), acute lymphoblastic leukemia (ALL; n = 620), myelodysplastic syndrome (MDS; n = 170), and lymphoma (n = 128). Multivariate analysis for overall survival (OS) demonstrated the benefit of adding high-dose cytarabine to the Cy/TBI regimen for the AML group (relative risk [RR], .76; P = .003) and lymphoma group (RR, .54; P = .02), but not for the ALL and MDS groups. In the ALL group, adding etoposide to the Cy/TBI regimen was associated with a lower OS (RR, 1.45; P = .03). For GVHD prophylaxis, a tacrolimus/methotrexate regimen was associated with a lower OS compared with a cyclosporine/methotrexate regimen in the AML group (RR, 1.26; P = .01); this difference was not observed in the other groups. These differences in OS according to the conditioning and GVHD prophylaxis regimen were attributable mainly to differences in relapse risk. Our data show that the effects of conditioning regimens and GVHD prophylaxis on UCBT outcomes differed according to disease type. UCBT outcomes could be improved by selecting optimal conditioning regimens and GVHD prophylaxis for each disease type.