Unit selection for umbilical cord blood transplantation for adults with acute myeloid leukemia in complete remission: a Japanese experience

Levels of C-Reactive Protein and Body Temperature Elevation During Neutropenia Predict Engraftment and Non-Relapse Mortality for Unrelated Single-Unit Cord Blood Transplantation in Adults

Cord blood transplantation (CBT) presents unique challenges related to inflammation during neutropenia, such as mucosal damage, infections, and the potential development of pre-engraftment syndrome or pre-engraftment immune reaction. These factors can contribute to significant inflammation and infection shortly after CBT. However, the effect of severe inflammation during neutropenia, specifically elevated C-reactive protein (CRP) level and body temperature, on post-transplant outcomes after CBT remains unclear. This retrospective study aimed to investigate the association between maximum CRP level, maximum body temperature during neutropenia, and post-transplantation outcomes in adult patients undergoing single-unit CBT. We retrospectively evaluated the impact of maximum CRP level and maximum body temperature during neutropenia on post-transplantation outcomes in adults who underwent single-unit unrelated CBT between 1998 and 2023 at our institution. A total of 336 adult patients were included in this study. The median maximum CRP level before neutrophil recovery was 7.75 mg/dL (interquartile range [IQR], 4.70 to 12.05 mg/dL) at a median of 14 d (IQR, 8 to 16 d). The median maximum body temperature before neutrophil recovery was 39.5°C (IQR, 39.0 to 40.0°C) at a median of 15 d (IQR, 12 to 17 d). In the multivariate analysis, a maximum CRP level≥20 mg/dL was significantly associated with lower neutrophil recovery (hazard ratio [HR], 0.37; 95% confidence interval [CI], 0.23 to 0.59; P < .001), lower platelet recovery (HR, 0.28; 95% CI, 0.16 to 0.48; P < .001), and a higher incidence of veno-occlusive disease/sinusoidal obstruction syndrome (HR, 16.42; 95% CI, 4.11 to 65.54; P < .001), which resulted in higher non-relapse mortality (NRM) (HR, 5.16; 95% CI, 2.62 to 10.15; P < .001) and worse overall survival (HR, 2.81; 95% CI, 1.66 to 4.78; P < .001). Similarly, a maximum body temperature≥40.5°C was significantly associated with lower neutrophil recovery (HR, 0.51; 95% CI, 0.33 to 0.79; P = .002), lower platelet recovery (HR, 0.55; 95% CI, 0.38 to 0.79; P = .001), higher incidence of grades III to IV acute GVHD (HR, 2.93; 95% CI, 1.24 to 6.88; P = .013), and extensive chronic GVHD (HR, 2.47; 95% CI, 1.22 to 4.97; P = .011), which resulted in higher NRM (HR, 3.43; 95% CI, 1.53 to 7.67; P = .002). Maximum CRP level and maximum body temperature during neutropenia were significantly associated with lower hematopoietic recovery and higher NRM following single-unit CBT in adults. Further studies are warranted to explore early intervention strategies aimed at preventing severe inflammation and improving post-transplant outcomes in single-unit CBT.

Allogeneic hematopoietic cell transplantation from alternative donors in acute myeloid leukemia

Allogeneic hematopoietic cell transplantation (HCT) potentially provides a cure for patients with acute myeloid leukemia (AML) who are unlikely to be cured with chemotherapy alone. Previously, human leukocyte antigen (HLA)-matched related donors were used exclusively, which made the procedure available for a limited proportion of patients. The introduction of high-resolution HLA-typing technology, innovations in immunosuppressive therapy, and improved supportive care measures have significantly changed the situation. Now, patients without a matched related donor have an ample opportunity to receive allogeneic HCT with the use of matched or mismatched unrelated donors, umbilical cord blood grafts, or haploidentical related donors. The outcomes of alternative donor transplantations have improved over the past decades, and the growth of unrelated donor registries as well as the donor diversification have enhanced the chance of finding a suitable donor. With multiple alternative donor choices available for most patients, the donor selection is becoming increasingly important. To discuss the optimal donor choice in case of unavailability of an HLA-matched related donor, this article reviews the existing literature of retrospective and prospective comparisons of different alternative donor transplantations in AML and discusses the current state-of-art modalities in allogeneic HCT using alternative donors.

The effect of center experience on allogeneic hematopoietic cell transplantation outcomes in acute myeloid leukemia

This study aimed to address the prognostic impact of center experience based on the data of 7821 adults with acute myeloid leukemia who underwent allogeneic hematopoietic cell transplantation (HCT) from 2010 to 2019 in Japan, where medical care was provided within a uniform healthcare system. Center experience was defined based on the number of allogeneic HCTs performed for any indication during the study period, by which centers were divided into low-, intermediate-, and high-volume centers. After adjusting for known confounding factors, the risk of overall mortality was lowest for the high-volume centers and highest for the low-volume centers, with the difference between the center categories attributed primarily to the risk of relapse. Patients transplanted at high-volume centers had higher risks of acute and chronic graft-versus-host diseases but without an increased risk of non-relapse mortality (NRM). These findings reveal the presence of a center effect in allogeneic HCT conducted during the past decade in Japan, highlighting the difference in relapse based on center experience. The weaker effect on NRM compared with that on relapse suggests that the transplantation care quality is becoming equalized across the country.

Scoring system for optimal cord blood unit selection for single cord blood transplantation

BACKGROUND

We conducted a retrospective study to categorize the cord blood unit (CBU)s to identify the optimal units.

METHODS

A total of 8503 adults (female, n = 3592; male, n = 4911) receiving their first single cord blood transplantation (CBT) in 2000-2019 were analyzed. Factors associated with CBUs affecting overall survival (OS) and neutrophil engraftment were selected to create ranked categorization for each outcome, followed by comparison with transplantation using HLA-matched bone marrow (BMT)/peripheral blood stem cell (PBSCT) from unrelated (n = 6052) and related donors (n = 4546).

RESULTS

Sex-mismatch, CD34+ cell and CFU-GM counts were selected in the OS analysis. Considering the strong interaction between sex mismatch and CD34+ cell counts, we analyzed females and males separately. For females, female CBU with CD34+ cell counts {greater than or equal to} 0.5 × 10e5/kg and CFU-GM counts {greater than or equal to} 15 × 10e3/kg offered the best OS (Group I), followed by other groups with any (Groups II-IV) or all (Group V) of the risk factors. Group I consistently showed favorable OS (Group IV: HR1.22, P = 0.027; Group V: HR1.31, P = 0.047), comparable to those of rBMT/PBSCT (OS: HR1.02, P = 0.654) and uBM/PBSCT in patients with higher rDRI (HR1.07, P = 0.353). Male patients lacked significant factors affecting OS. Categorization for neutrophil engraftment consisting of CD34+ cell and CFU-GM counts, sex-mismatch, presence of donor-specific antibodies, and the number of HLA-mismatches was effective but not predicted OS.

CONCLUSION

Our ranked categorizations sufficiently predicted female OS and engraftment. The best-ranked CBUs offered preferable outcomes comparable to conventional BM/PB donors in female but not in male patients.

Cord blood transplantation for adult mature lymphoid neoplasms in Europe and Japan

ABSTRACT

To clarify the different characteristics and prognostic factors of cord blood transplantation (CBT) in adult patients with lymphoid neoplasms in Europe and Japan, we conducted a collaborative study. Patients aged 18-75 years receiving their first CBT (Europe: single CBT, n = 192; double CBT, n = 304; Japan: single CBT, n = 1150) in 2000-2017 were analyzed. Fewer patients with Hodgkin lymphoma (Europe vs Japan, 26% vs 5%), and older patients (≥50 years) (39% vs 59%) with a higher refined disease risk index (rDRI) (high-very high: 49% vs 14%) were included in the Japanese registry. High-very high rDRI was associated with inferior overall survival (OS) (vs low rDRI, Europe: hazard ratio [HR], 1.87; P = .001; Japan: HR, 2.34; P < .001) with higher progression/relapse risks. Total body irradiation (TBI)-containing conditioning contributed to superior OS both in Europe (vs TBI-reduced-intensity conditioning [RIC], non-TBI-RIC: HR, 1.93; P < .001; non-TBI-Myeloablative conditioning [MAC]: HR, 1.90; P = .003) and Japan (non-TBI-RIC: HR, 1.71; P < .001; non-TBI-MAC: HR 1.50, P = .007). The impact of HLA mismatches (≥2) on OS differed (Europe: HR, 1.52; P = .007; Japan: HR, 1.18; P = .107). CBT for lymphoid neoplasms, especially in those with high rDRI showed poor outcomes despite all the different characteristics in both registries. TBI should be considered in conditioning regimens to improve these outcomes. The different impacts of HLA mismatches call attention to the fundamental differences among these populations.

Comparison of long-term outcomes after first HLA-mismatched unrelated donor transplantation with single unrelated cord blood transplantation using reduced-intensity or reduced-toxicity conditioning

BACKGROUND

No comparative data have shown significant survival differences between HLA-mismatched unrelated donor (MMUD) transplantation and cord blood (CB) transplantation, each with reduced-intensity/reduced-toxicity conditioning (RIC/RTC). However, advances in graft-versus-host disease (GVHD) prophylaxis might help update current strategies.

METHODS

We retrospectively compared the outcomes of first allogeneic hematopoietic cell transplantation from MMUDs (n = 15) or single unrelated CB (n = 35) after RIC/RTC.

RESULTS

The median age was 60 years. The MMUD group had a numerically lower 100-day incidence of grade III-IV acute GVHD (7% vs. 29%, P = 0.079) and non-relapse mortality (0% vs. 40%, P = 0.12). Eight MMUD recipients received anti-thymocyte globulin, bortezomib, or posttransplant cyclophosphamide for GVHD prophylaxis. They did not develop grade III-IV acute GVHD. The MMUD group had significantly better 5-year overall survival than the CB group (62% vs. 31%, P = 0.021), although relapse rates were similar. A multivariable analysis and sensitivity analysis also showed trends toward higher overall survival in the MMUD group.

CONCLUSION

MMUD with better GVHD prophylaxis might be preferred over CB in patients with older age and comorbidities.

Comparison of Allogeneic Transplant Outcomes Between Matched Sibling Donors and Alternative Donors in Patients Over 50 Years of Age with Acute Myeloid Leukemia: 8/8 Allele-Matched Unrelated Donors and Unrelated Cord Blood Provide Better Leukemia-Free Survival Compared with Matched Sibling Donors During Nonremission Status

Acute myeloid leukemia (AML) is the most common indication for allogeneic hematopoietic cell transplantation (HCT). The increased availability of alternative donor sources has broadened donor types for older patients without HLA-matched sibling donors (MSD). It is uncertain if an MSD should be the first option for allogeneic HCT in patients with AML over 50 years of age. The objective of this study was to compare survival and other post-transplant outcomes between MSDs, 8/8 allele-matched unrelated donors (MUDs), 7/8 allele-MUDs, unrelated cord blood (UCB), and haploidentical donors for patients with AML over 50 years of age. We conducted a retrospective study to compare outcomes in 5704 patients with AML over 50 years of age and receiving allogeneic HCT between 2013 and 2021, using either MSD, 8/8 allele-MUD, 7/8 allele-MUD, UCB, or haploidentical donors in Japan. Complete remission (CR) and nonremission at HCT were analyzed separately for all analyses. In total, 3041 patients were CR, and 2663 patients were nonremission at the time of HCT. In multivariate analysis, donor type did not determine overall survival, irrespective of disease status at HCT. Leukemia-free survival (LFS) was significantly better for 8/8 allele-MUD (hazard ratio [HR], 0.77; 95% confidence interval [CI], 0.64 to 0.93; P = .005) and UCB (HR, 0.76; 95% CI, 0.65 to 0.88; P < .001), but not for 7/8 allele-MUD (HR, 0.97; 95% CI, 0.79 to 1.19; P = .794), and haploidentical donor (HR, 0.86; 95% CI, 0.70 to 1.05; P = .146) compared to the MSD group in nonremission status. However, donor type did not determine LFS among CR status. Relapse rates were significantly lower for 8/8 allele-MUD and UCB, whereas nonrelapse mortality was higher for UCB compared to the MSD group among both CR and nonremission status. Our registry-based study demonstrated that MSDs do not lead to superior survival compared to alternative donors for patients with AML over 50 years of age. Furthermore, 8/8 allele-MUDs and UCB provide better LFS compared with MSDs during nonremission status. Therefore, MSD is not necessarily the best donor option for allogeneic HCT in this population.

[Single non-blood-related umbilical cord blood transplantation using a reduced-intensity conditioning regimen for the treatment of severe aplastic anemia]

Objective: To evaluated the clinical efficacy of a reduced-intensity preconditioning regimen for single non-blood-related umbilical cord blood transplantation (sUCBT) in the treatment of severe aplastic anemia (SAA) . Methods: The clinical data of 63 patients with SAA who underwent sUCBT from January 2021 to July 2023 at the Department of Hematology of the First Affiliated Hospital of USTC were retrospectively analyzed. Fifty-two patients received total body irradiation/total bone marrow irradiation (TMI) combined with fludarabine or a cyclophosphamide- conditioning regimen (non-rATG group) , while 11 patients received rabbit anti-human thymocyte immunoglobulin (rATG) combined with TMI, fludarabine, or the cyclophosphamide-conditioning regimen (rATG group) . All patients received cyclosporine A and mycophenolate mofetil for graft-versus-host disease (GVHD) prophylaxis. Complications post-transplantation and long-term survival were compared between the two groups. Results: The baseline parameters were balanced between the two groups (P>0.05) . In the rATG group, all patients achieved stem cell engraftment, and in the non-rATG group, five patients had primary graft failure. There was no significant difference in the cumulative incidence of neutrophil engraftment at 42 days after transplantation or platelet engraftment at 60 days between the two groups. The incidence of grade Ⅱ-Ⅳ acute GVHD in the rATG group was significantly lower than in the non-rATG group (10.0% vs. 46.2% , P=0.032) , and the differences in the cumulative incidences of grade Ⅲ/Ⅳ acute GVHD and 1-year chronic GVHD were not statistically significant (P=0.367 and P=0.053, respectively) . There were no significant differences in the incidences of pre-engraftment syndrome, bacterial bloodstream infections, cytomegalovirus viremia, or hemorrhagic cystitis between the two groups (P>0.05 for all) . The median follow-up time for surviving patients was 536 (61-993) days, and the 1-year transplantation related mortality (TRM) of all patients after transplantation was 13.0% (95% CI 6.7% -24.3% ) . Among the patients in the non-rATG and rATG groups, 15.5% (95% CI 8.1% -28.6% ) and 0% (P=0.189) , respectively, had mutations. The 1-year overall survival (OS) rate of all patients after transplantation was 87.0% (95% CI 75.7% -93.3% ) . The 1-year OS rates in the rATG group and non-rATG group after transplantation were 100% and 84.5% , respectively (95% CI 71.4% -91.9% ) (P=0.198) . Conclusion: The preliminary results of sUCBT with a low-dose irradiation-based reduced-intensity conditioning regimen with fludarabine/cyclophosphamide for the treatment of patients with SAA showed good efficacy. Early application of low-dose rATG can reduce the incidence of acute GVHD after transplantation without increasing the risk of implantation failure or infection.

External validation and extended application of the transplant conditioning intensity score in acute myeloid leukemia

This study aimed to validate the utility of the transplant conditioning intensity (TCI) score in 1714 patients with acute myeloid leukemia (AML) undergoing allogeneic bone marrow or peripheral blood stem cell transplantation (BMT/PBSCT) and assess its applicability to 753 patients with AML undergoing umbilical cord blood transplantation (UCBT) both during first complete remission. Patients classified into a high TCI group accounted for 63% and 56% in the BMT/PBSCT and UCBT cohorts, respectively. In the BMT/PBSCT cohort, the risk of relapse was lower in patients in the high versus intermediate TCI group (P = 0.002), although non-relapse mortality (NRM) did not differ among the three TCI groups. In the UCBT cohort, both relapse and NRM did not differ among the TCI groups. Increasing cutoff points for intermediate and high TCI categories significantly improved the ability to predict relapse and NRM in the BMT/PBSCT cohort (P = 0.030 and 0.006, respectively), and relapse but not NRM in the UCBT cohort (P = 0.005 and 0.364, respectively). These findings highlight the difference in the threshold level of the TCI score for outcome discrimination between European and Japanese cohorts. The TCI scheme appears less effective for UCBT than for BMT/PBSCT.

Refining eligibility criteria of unit selection for myeloablative cord blood transplantation in acute leukemia: Real-world experience of a referral center

The algorithm for cord blood (CB) unit selection is still somewhat ambiguous. We retrospectively analyzed 620 cases of acute leukemia between 2015 and 2020, who were treated with myeloablative single-unit umbilical CB transplantation (UCBT). We found that, when human leukocyte antigen (HLA) mismatch was ≤3/10, CD34+ cell dosage <0.83 × 105/kg-considerably lower than prevalent guidelines-was permissible without affecting survival. Moreover, synergy between donor killer-cell immunoglobulin-like receptors (KIR) haplotypes-B and donor-recipient HLA-C mismatch protected against relapse-related mortality. We submit that minimum required CD34+ cell dosage can possibly be relaxed to broaden access to UCBT, and donor KIR genotyping should be considered during unit selection.

Comparison of transplant outcomes between haploidentical transplantation and single cord blood transplantation in non-remission acute myeloid leukaemia: A nationwide retrospective study

Allogeneic haematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for some patients with acute myeloid leukaemia (AML) who are refractory to chemotherapy. Cord blood transplantation (CBT) is a reasonable option in such cases because of its rapid availability. Recently, a growing number of human leucocyte antigen (HLA)-haploidentical related donor HSCTs (haplo-HSCTs) have been performed, although its effectiveness remains undetermined. Using the Japanese nationwide transplantation registry data, we identified 2438 patients aged ≥16 years who received CBT or haplo-HSCT as their first transplant for non-remission AML between January 2008 and December 2018. After 2:1 propensity score matching, 918 patients in the CBT group and 459 patients in the haplo-HSCT group were selected. In this matched cohort, no significant difference in overall survival (OS) was observed between the CBT and haplo-HSCT groups (hazard ratio [HR] of haplo-HSCT to CBT 1.02, 95% confidence interval [CI] 0.89-1.16). Similarly, no significant difference in the cumulative incidence of relapse (HR 1.09, 95% CI 0.93-1.28) or non-relapse mortality (HR 0.94, 95% CI 0.76-1.18). Subgroup analysis showed that CBT was significantly associated with preferable OS in patients receiving myeloablative conditioning. Our data showed comparable outcomes between haplo-HSCT and CBT recipients with non-remission AML.

Effect of graft-versus-host disease on posttransplant outcomes following single cord blood transplantation in comparison to haploidentical transplantation with posttransplant cyclophosphamide for adult acute myeloid leukemia

BACKGROUND

The possibility that human leukocyte antigen (HLA) mismatches could reduce relapse after alternative HLA-mismatched allogeneic hematopoietic cell transplantation (HCT) is an attractive concept for acute myeloid leukemia (AML). However, it remains unclear whether the prognostic effect of graft-versus-host disease (GVHD) on survival differs between single-unit cord blood transplantation (CBT) or haploidentical HCT using posttransplant cyclophosphamide (PTCy-haplo HCT) for AML.

OBJECTIVE

The objective of this retrospective study was to compare the effect of acute and chronic GVHD on posttransplant outcomes between CBT and PTCy-haplo HCT.

STUDY DESIGN

We retrospectively evaluated the effect of acute and chronic GVHD on posttransplant outcomes following CBT and PTCy-haplo HCT in adults with AML (n=1,981) between 2014 and 2020 using a Japanese registry database.

RESULTS

In the univariate analysis, the probability of overall survival was significantly greater in patients who developed grade I-II acute GVHD (P<0.001 by log-rank test) and limited chronic GVHD (P<0.001 by log-rank test) among CBT recipients, but these effects were not significant among PTCy-haplo HCT recipients. In the multivariate analysis, in which the development of GVHD was treated as a time-dependent covariate, the effect of grade I-II acute GVHD on reducing overall mortality was significant between CBT and PTCy-haplo HCT (adjusted hazard ratio [HR] for CBT: 0.73, 95% confidence interval [CI]: 0.60-0.87; adjusted HR for PTCy-haplo HCT: 1.07, 95% CI: 0.70-1.64; p for interaction=0.038).

CONCLUSION

Our data demonstrate that grade I-II acute GVHD was associated with a significant improvement in overall mortality in adults with AML receiving CBT but not PTCy-haplo HCT.

Conditioning regimens for allogeneic hematopoietic cell transplantation in acute myeloid leukemia: Real-world data from the Japanese registry studies

Conditioning regimens play a crucial role in preventing relapse of acute myeloid leukemia (AML) following allogeneic hematopoietic cell transplantation (HCT). In early times, myeloablative conditioning was used exclusively, but it was associated with significant toxicity. However, the advent of reduced-intensity conditioning has allowed allogeneic HCT to be performed more safely, leading to an expansion of our choices for conditioning regimens. As the transplantation methods have become highly diversified, it is reasonable to determine an optimal conditioning regimen in consideration of patient-, disease-, and transplantation-related factors. In this context, large-scale registry-based studies provide real-world data to allow for a detailed evaluation of the utility of individual conditioning regimens in specific clinical settings. The Japanese Society for Transplantation and Cellular Therapy has been conducting a nationwide survey for HCT since 1993 that currently covers >99% of all the transplantation centers nationwide, and >1,000 allogeneic HCTs performed for adults with AML are registered per year. We have been using the registry data to implement a number of studies focusing on adults with AML, and the large number of patients registered consecutively from nearly all transplantation centers nationwide represent real-world practice in Japan. This article reviews and discusses the results obtained from our registry-based studies pertaining to various conditioning regimens.

Improved trends in survival and engraftment after single cord blood transplantation for adult acute myeloid leukemia

Unrelated cord blood transplantation (CBT) is an alternative curative option for adult patients with acute myeloid leukemia (AML) who need allogeneic hematopoietic cell transplantation (HCT) but lack an HLA-matched related or unrelated donor. However, large-scale data are lacking on CBT outcomes for unselected adult AML. To investigate the trends of survival and engraftment after CBT over the past 22 years, we retrospectively evaluated the data of patients with AML in Japan according to the time period of CBT (1998-2007 vs 2008-2013 vs 2014-2019). A total of 5504 patients who received single-unit CBT as first allogeneic HCT for AML were included. Overall survival (OS) at 2 years significantly improved over time. The improved OS among patients in ≥ complete remission (CR)3 and active disease at CBT was mainly due to a reduction of relapse-related mortality, whereas among patients in first or second CR at CBT, this was due mainly to a reduction of non-relapse mortality. The trends of neutrophil engraftment also improved over time. This experience demonstrated that the survival and engraftment rate after CBT for this group has improved over the past 22 years.

Umbilical cord blood transplantation: Still growing and improving

Umbilical cord blood transplantation (UCBT) has been performed in the clinic for over 30 years. The biological and immunological characteristics of umbilical cord blood (UCB) have been re-recognized in recent years. UCB, previously considered medical waste, is rich in hematopoietic stem cells (HSCs), which are naïve and more energetic and more easily expanded than other stem cells. UCB has been identified as a reliable source of HSCs for allogeneic hematopoietic stem cell transplantation (allo-HSCT). UCBT has several advantages over other methods, including no harm to mothers and donors, an off-the-shelf product for urgent use, less stringent HLA match, lower incidence and severity of chronic graft-vs-host disease (GVHD), and probably a stronger graft-vs-leukemia effect, especially for minimal residual disease-positive patients before transplant. Recent studies have shown that the outcome of UCBT has been improved and is comparable to other types of allo-HSCT. Currently, UCBT is widely used in malignant, nonmalignant, hematological, congenital and metabolic diseases. The number of UCB banks and transplantation procedures increased exponentially before 2013. However, the number of UCBTs increased steadily in Asia and China but decreased in the United States and Europe year-on-year from 2013 to 2019. In this review, we focus on the development of UCBT over the past 30 years, the challenges it faces and the strategies for future improvement, including increasing UCB numbers, cord blood unit selection, conditioning regimens and GVHD prophylaxis for UCBT, and management of complications of UCBT.

Allogeneic Hematopoietic Cell Transplantation from Alternative Donors in Acute Myelogenous Leukemia: A Comparative Analysis

In the absence of HLA-matched related and unrelated donors, alternative donors must be found for patients in need of allogeneic hematopoietic cell transplantation (HCT). There are at least 3 donor options: a mismatched unrelated donor (MMUD), umbilical cord blood (UCB), and a haploidentical related donor (haplo); however, the optimal alternative donor type remains to be established. This study aimed to address how the outcomes of patients receiving these 3 alternative donor HCTs differ, and whether these outcomes change over time post-transplantation. We retrospectively analyzed Japanese nationwide transplantation registry data of adults with acute myelogenous leukemia (AML) undergoing allogeneic HCT while in first complete remission (CR) from an MMUD with a 7/8 match at the allele level (n = 601), with UCB (n = 1110), or from a haploidentical related donor (n = 221) between 2007 and 2018. For patients who underwent transplantation between 2007 and 2014, the 3-year overall survival (OS) for the MMUD, UCB, and Haplo groups was 60%, 54%, and 47%, respectively (P = .022). For those who underwent transplantation between 2015 and 2018, the 3-year OS in these groups was 60%, 66%, and 63%, respectively (P = .693). Multivariate analysis revealed that the risks of both overall mortality and nonrelapse mortality (NRM) were significantly lower in the later period than in the earlier period in the UCB group (hazard ratio [HR], 0.66 [P < .001] for OS; HR, 0.64 [P < .001] for NRM) and the Haplo group (HR, 0.58 [P = .019 for OS; HR, 0.39 [P = .004] for NRM), but not in the MMUD group (HR, 1.07 [P = .631] for OS; HR, 1.26 [P = .175] for NRM). The results of a test for interaction showed a significant difference in the effect of transplantation period on OS and NRM between the MMUD and UCB groups (P = .014 for OS; P = .004 for NRM) and between the MMUD and Haplo groups (P = .034 for OS; P = .003 for NRM). These findings demonstrate the recent improvements in the outcomes of UCB and Haplo transplantations in patients with AML in first CR that have resulted in a similar OS in patients undergoing HCT with grafts from MMUDs, UCB, and haploidentical donors in the later period of the study.

The differential effect of disease status at allogeneic hematopoietic cell transplantation on outcomes in acute myeloid and lymphoblastic leukemia

This study aimed to compare the effect of disease status at the time of allogeneic hematopoietic cell transplantation (HCT) on post-transplant outcomes between acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Japanese nationwide registry data for 6901 patients with AML and 2469 patients with ALL were analyzed. In this study, 2850 (41%), 937 (14%), 62 (1%), and 3052 (44%) AML patients and 1751 (71%), 265 (11%), 23 (1%), and 430 (17%) ALL patients underwent transplantation in first complete remission (CR1), second CR (CR2), third or subsequent CR (CR3 +), and non-CR, respectively. The probabilities of overall survival at 5 years for patients transplanted in CR1, CR2, CR3 + , and non-CR were 58%, 61%, 41%, and 26% for AML patients and 67%, 45%, 20%, and 21% for ALL patients, respectively. Multivariate analyses revealed that the risks of relapse and overall mortality were similar for AML patients transplanted in CR1 and CR2 (P = 0.672 and P = 0.703), whereas they were higher for ALL patients transplanted in CR2 than for those transplanted in CR1 (P < 0.001 for both). The risks of relapse and overall mortality for those transplanted in CR3 + and non-CR increased in a stepwise manner for both diseases, with the relevance being stronger for ALL than for AML patients. These results suggest a significant difference in the effect of disease status at HCT on post-transplant outcomes in AML and ALL. Further investigation to incorporate measurable residual disease data is warranted.

Difference in outcomes following allogeneic hematopoietic cell transplantation for patients with acute myeloid leukemia and myelodysplastic syndromes

To evaluate whether outcomes following allogeneic hematopoietic cell transplantation differ according to disease type, a three-way comparison for patients with de novo acute myeloid leukemia (AML) (n = 3318), AML evolving from myelodysplastic syndromes (MDS) (n = 208), and MDS with excess blasts (MDS-EB) (n = 994) was performed. The 5-year probabilities of overall survival (OS) for de novo AML, AML evolving from MDS, and MDS-EB were 60%, 42%, and 41% (p < 0.001), respectively. Multivariate analysis revealed that, compared to de novo AML, AML evolving from MDS was associated with a higher risk of NRM (p = 0.030) and MDS-EB with a higher risk of relapse (p < 0.001), both leading to lower OS (p = 0.010 and p < 0.001, respectively). These findings demonstrate inter-disease differences in post-transplant outcomes and highlight the needs to reduce NRM for AML evolving from MDS and to reduce relapse for MDS-EB.

Cord blood index predicts engraftment and early non-relapse mortality in adult patients with single-unit cord blood transplantation

How to select optimal cord blood (CB) remains an important clinical question. We developed and validated an index of CB engraftment, the cord blood index (CBI), which uses three weighted variables representing cell doses and HLA mismatches. We modeled the neutrophil engraftment time with competing events by random survival forests for competing risks as a function of the predictors: total nucleated cells, CD34, colony-forming units for granulocytes/macrophages, and the number of HLA mismatches at the antigen and allele levels. The CBI defined three groups that had different neutrophil engraftment rates at day 30 (High, 83.7% [95% CI, 79.2-88.1%]; Intermediate, 77.0% [95% CI, 73.7-80.2%]; Low, 68.4% [95% CI, 63.6-73.2%]), platelet engraftment rates at day 60 (High, 70.4% [95% CI, 64.9-75.9%]; Intermediate, 62.3% [95% CI, 58.5-66.0%]; Low, 49.3% [95% CI, 44.2-54.5%]), and non-relapse mortality at day 100 (High, 14.1% [95% CI, 9.9-18.3%]; Intermediate, 16.4% [95% CI, 13.5-19.3%]; Low, 21.3% [95% CI, 17.1-25.5%]). This novel approach is clinically beneficial and can be adopted immediately because it uses easily obtained pre-freeze data of CB.

Single cord blood transplantation for acute myeloid leukemia patients aged 60 years or older: a retrospective study in Japan

The availability of alternative donor sources could allow elderly patients to receive allogeneic hematopoietic cell transplantation (HCT). We retrospectively evaluated the outcomes of single-unit cord blood transplantation (CBT) in 1577 patients aged ≥60 years with acute myeloid leukemia (AML) in Japan between 2002 and 2017. In total, 990 (63%) patients were not in complete remission (CR) at the time of CBT. A myeloablative conditioning regimen (52%) and calcineurin inhibitor (CI) + mycophenolate mofetil (MMF)-based graft-versus-host disease (GVHD) prophylaxis (45%) were more commonly used. With a median follow-up for survivors of 31 months, the probability of overall survival and the cumulative incidence of leukemia-related mortality at 3 years was 31% and 29%, respectively. The cumulative incidence of non-relapse mortality (NRM) at 100 days and 3 years were 24% and 41%, respectively. The cumulative incidences of grade II-IV and grade III-IV acute GVHD at 100 days and extensive chronic GVHD at 2 years were 44%, 16%, and 14%, respectively. The cumulative incidence of neutrophil engraftment was 80% at 42 days. Results of multivariate analysis indicated that the following factors were significantly associated with higher overall mortality: performance status ≥1, hematopoietic cell transplantation-specific comorbidity index ≥3, adverse cytogenetics, extramedullary disease at diagnosis, and non-CR status at CBT. By contrast, female sex, HLA disparities ≥2, mycophenolate mofetil-based GVHD prophylaxis, and recent CBT were significantly associated with lower overall mortality. In conclusion, single CBT offers a curative option for AML patients aged ≥60 years with careful patient selection.

Allogeneic Hematopoietic Cell Transplantation for Adolescent and Young Adult Patients with Acute Myeloid Leukemia

Limited data exist regarding the outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) among adolescent and young adult (AYA) patients with acute myeloid leukemia (AML). Here we analyzed the features and outcomes of AYA patients with AML who had achieved complete remission (CR) and those who had not (non-CR) at allo-HCT. We retrospectively analyzed 2350 AYA patients with AML who underwent allo-HCT with a myeloablative conditioning regimen and who were consecutively enrolled in the Japanese nationwide HCT registry. The difference in overall survival (OS) between younger (age 16 to 29 years) and older AYA (age 30 to 39 years) patients in CR at transplantation was not significant (70.2% versus 71.7% at 3 years; P = .62). Meanwhile, this difference trended toward a statistical significance between younger and older AYA patients in non-CR at transplantation (39.5% versus 34.3% at 3 years; P = .052). In AYA patients in CR and non-CR, the age at transplantation did not affect relapse or nonrelapse mortality (NRM). In AYA patients in CR, no difference in OS was observed between those who received total body irradiation (TBI) and those who did not (71.1% versus 70.5% at 3 years; P = .43). AYA patients who received TBI-based conditioning had a significantly lower relapse rate and higher NRM than those who underwent non-TBI-based conditioning (relapse: 19.8% versus 24.1% at 3 years [P = .047]; NRM: 14.7% versus 11.1% at 3 years [P = .021]). In contrast, among the non-CR patients, there were no differences between the TBI and non-TBI groups with respect to OS (P = .094), relapse (P = .83), and NRM (P = .27). Our data indicate that outcomes may be more favorable in younger AYA patients than in older AYA patients in non-CR at transplantation, and that outcomes of TBI-based conditioning could be comparable to those of non-TBI-based conditioning for AYA patients.

Single Cord Blood Transplantation Versus Unmanipulated Haploidentical Transplantation for Adults with Acute Myeloid Leukemia in Complete Remission

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative post-remission therapy for adult patients with acute myeloid leukemia (AML) in complete remission (CR). The availability of alternative human leukocyte antigen (HLA)-mismatched donors, such as cord blood and haploidentical related donors, could allow patients to receive allogeneic HCT who are without an HLA-matched sibling or unrelated donor. The use of these alternative donors is preferable for patients with advanced disease due to the rapid availability. However, comparative data for cord blood transplantation (CBT) and haploidentical related donor transplantation (haplo-HCT) are limited for adult patients with AML in CR. We sought to compare overall survival (OS); leukemia-free survival (LFS); graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS); and chronic GVHD-free, relapse-free survival (CRFS) between single-unit CBT (SCBT) and haplo-HCT recipients for adult patients with intermediate- or poor-risk AML in CR. We retrospectively analyzed and compared the results of allogeneic hematopoietic cell transplantation in 1313 adult patients with intermediate- or poor-risk AML in CR who received either SCBT (n = 1102) or unmanipulated haplo-HCT (n = 211) between 2007 and 2018 in Japan. Among the whole cohort, the cumulative incidences of neutrophil and platelet recovery were significantly lower in SCBT recipients compared with those in haplo-HCT recipients (P < .001 for neutrophil, P < .001 for platelet). SCBT was significantly associated with a higher incidence of grade II to IV acute GVHD and lower incidence of extensive chronic GVHD compared to haplo-HCT (P = .013 for grades II to IV acute GVHD; P = .006 for extensive chronic GVHD). Haplo-HCT recipients developed a higher incidence of cytomegalovirus (CMV) antigenemia compared to SCBT recipients (P = .004). In the multivariate analysis, there were no significant differences for grades III or IV acute GVHD (hazard ratio [HR], 1.17; 95% confidence interval [CI], .88 to 1.57; P = .26), relapse incidence (HR, 1.09; 95% CI, .76 to 1.58; P = .61), non-relapse mortality (HR, .83; 95% CI, .58 to 1.18; P = .32), OS (HR, .92; 95% CI, .70 to 1.20; P = .56), LFS (HR, .94; 95% CI, .73 to 1.21; P = .67), GRFS (HR, 1.12; 95% CI, .90 to 1.40; P = .27), or CRFS (HR, 1.15; 95% CI, .92 to 1.44; P = .19) between the two donor types. In the propensity score matching analysis, which identified 180 patients in each cohort, there were no significant differences in transplant outcomes between the two donor types, except for delayed neutrophil (P < .001) and platelet recovery (P < .001) and a higher incidence of grades II to IV acute GVHD (P = .052) in SCBT. SCBT and unmanipulated haplo-HCT had similar survival outcomes for adult patients with AML in CR despite the lower hematopoietic recovery and higher grade II to IV acute GVHD in SCBT recipients and the higher CMV antigenemia in haplo-HCT recipients.

Outcome predictors after retransplantation in relapsed acute lymphoblastic leukemia: a multicenter, retrospective study

Retransplantation is the only curative treatment option for patients with acute lymphoblastic leukemia (ALL) that has relapsed after allogeneic hematopoietic cell transplantation (allo-HCT); however, data in this setting remain scant. Hence, this multicenter, retrospective study aims to determine outcome predictors after retransplantation in relapsed ALL. We examined 55 recipients who underwent multiple allo-HCTs during 2006-2018. The 2-year overall survival (OS), progression-free survival (PFS), and non-relapse mortality rates were 35.9%, 29.1%, and 23.6%, respectively. We observed a trend of better outcome in Ph + ALL (n = 22) patients compared with non-Ph ALL (n = 33) patients; the 2-year PFS was 40.9% versus 21.2%, indicating a beneficial effect of more potent second- or third-generation tyrosine kinase inhibitors. Univariate analysis revealed that late relapse after the previous transplant was the only significant predictor of better transplant outcome among Ph + ALL patients, whereas factors related to prolonged OS/PFS in non-Ph ALL patients were late relapse after the previous transplant, longer duration from disease relapse/progression to second or more allo-HCT, disease status at the transplantation, and good performance status. Nevertheless, further investigations are warranted to determine whether novel molecular-targeted agents with higher efficacy and fewer toxicities could exceed conventional chemotherapies as a bridging strategy to next allo-HCT and improve the outcomes of non-Ph ALL patients.

Class II HLA mismatch improves outcomes following haploidentical transplantation with posttransplant cyclophosphamide

HLA disparity is the major predictor of outcome following unrelated donor (UD) transplantation, where a single mismatch (mm) at the HLA-A, HLA-B, HLA-C, or HLA-DRB1 locus leads to increased mortality, and mismatching at multiple loci compounds this effect. In contrast, HLA disparity has not been shown to increase mortality in the context of haploidentical transplant using posttransplant cyclophosphamide (PTCy). To better define the consequences of loci-specific HLA mm, we analyzed 208 consecutive patients undergoing haploidentical transplantation for hematologic malignancy using PTCy at our institution (median age, 52 years [range, 19-75 years]; peripheral blood stem cell, 66%; reduced-intensity conditioning, 59%). Median follow-up was 65.4 months (range, 34.3-157.2 months). In univariate analysis, a single class II HLA mm at HLA-DR, HLA-DQ or a nonpermissive (np) HLA-DP mm had a protective effect on disease-free and overall survival (OS), primarily a result of reduced relapse risk. Furthermore, this survival effect was cumulative, so that patients with 3 class II mm (HLA-DR, HLA-DQ, and np HLA-DP) had the best OS. In multivariate analysis, HLA-DR mm and np HLA-DP mm were both independently associated with improved OS (hazard ratio [HR], 0.43; P =.001; and HR, 0.47; P =.011, respectively). In contrast, single or multiple mm at HLA-A, HLA-B, or HLA-C loci had no effect on acute graft-versus-host disease (GVHD), nonrelapse mortality (NRM), relapse, or survival, although the presence of an HLA-A mm was associated with increased chronic GVHD incidence. The association of class II mm with lower relapse occurred without a corresponding increase in NRM or acute or chronic GVHD. These findings will require validation in larger registry studies.

Lower vancomycin trough levels in adults undergoing unrelated cord blood transplantation

Vancomycin (VCM) is frequently used for neutropenic patients undergoing cord blood transplantation (CBT). We retrospectively examined the relationship between VCM trough levels and the efficacy and toxicity in 122 adult patients undergoing CBT in our institute. The median initial dose of VCM based on body weight was 9.1 mg/kg/dose (range, 6.0-22.6 mg/kg/dose). The median initial trough level of VCM for all patients was 4.50 µg/mL (range, 1.20-24.05 µg/mL), at a median of 3 days (range, 2-6 days) after VCM administration. The cumulative incidence of acute kidney injury (AKI) was 19% at 30 days after VCM administration. A higher median trough level of VCM during the first 7 days was significantly associated with the development of AKI in the multivariate analysis (Hazard ratio: 1.28, p = .026). These data suggest that a lower VCM trough level may be safe in adult patients undergoing CBT under therapy with nephrotoxic drugs.

Comparison of immunosuppressant regimens in salvage cord blood transplantation for graft failure after allogeneic hematopoietic stem cell transplantation

Graft failure (GF) is a life-threatening complication after allogeneic stem cell transplantation. Although salvage cord blood transplantation (CBT) is a curative therapy for GF, the optimal immunosuppression after salvage CBT remains unknown. Using nationwide registration data, we compared the transplant outcomes of patients who developed GF and underwent salvage CBT using immunosuppressants, including calcineurin (CNI) alone (n = 177); CNI plus methotrexate (CNI+MTX, n = 150); and CNI plus mycophenolate mofetil (CNI+MMF, n = 161). The CNI+MMF group, in comparison with the CNI+MTX and CNI alone groups, demonstrated better neutrophil recovery at 30 days (62.7 vs. 42.7 vs. 53.1%, P < 0.001); better overall survival (OS) at 12 months (48.4 vs. 33.5 vs. 28.3%, P < 0.001); and lower non-relapse mortality (NRM) at 12 months (35.2 vs. 53.9 vs. 56.5%, P < 0.001). On multivariate analysis, CNI+MMF had the best neutrophil recovery (hazard ratio (HR), 1.71; P < 0.001) and OS (HR, 0.64; P = 0.002) and the lowest NRM (HR, 0.53; P < 0.001). Hemorrhage was relatively less frequent in the CNI+MMF group. CNI+MMF can be a promising immunosuppressant regimen after salvage CBT for GF, with better engraftment and survival outcomes, compared with CNI alone and CNI+MTX.

Predicting non-relapse mortality following allogeneic hematopoietic cell transplantation during first remission of acute myeloid leukemia

The aim of this study was to develop a comprehensive system for predicting non-relapse mortality after allogeneic hematopoietic cell transplantation (HCT) during first complete remission (CR) of acute myeloid leukemia (AML). After dividing 2344 eligible patients randomly into a training set and a validation set, we first identified and scored five parameters, that is, age, sex, performance status, HCT-comorbidity index (HCT-CI), and donor type, on the basis of their impact on non-relapse mortality for patients in the training set. The non-relapse mortality-J (NRM-J) index using the sum of these scores was then applied to patients in the validation set, resulting in a clear differentiation of non-relapse mortality, with expected 2-year rates of 11%, 16%, 27%, and 33%, respectively (P < 0.001). The estimated c-statistic was 0.67, which was significantly higher than that of the European Society for Blood and Marrow Transplantation score (0.60, P = 0.002) and the HCT-CI (0.57, P < 0.001). The NRM-J index showed a significant association with overall survival, but not with relapse. Our findings demonstrate that the NRM-J index is useful for predicting post-transplant non-relapse mortality for patients with AML in first CR, for whom the decision of whether to perform allogeneic HCT is critical.

Guidelines for Cord Blood Unit Selection

Optimal cord blood (CB) unit selection is critical to maximize the likelihood of successful engraftment and survival after CB transplantation (CBT). However, unit selection can be complex because multiple characteristics must be considered including unit cell dose, donor-recipient human leukocyte antigen (HLA) match, and unit quality. This review provides evidence-based and experience-based comprehensive guidelines for CB unit selection. Topics addressed include the use of both the TNC and the CD34⁺ cell dose, as well as the CD34⁺ cell to TNC content ratio to evaluate unit progenitor cell content and engraftment potential, the acceptable TNC and CD34⁺ cell dose criteria that define an adequate single-unit graft, and the indication and acceptable cell dose criteria for double-unit grafts. The acceptable criteria for 6-loci (HLA-A, -B antigen, -DRB1 allele) and 8-allele (HLA-A, -B, -C, -DRB1) donor-recipient HLA match, the evaluation of patients with donor-specific HLA antibodies, and the multiple determinants of unit quality are also reviewed in detail. Finally, a practical step-by-step guide to CB searches and the principles that guide ultimate graft selection are outlined.

Long-term results of reduced-intensity conditioning allogeneic hematopoietic cell transplantation for older patients with acute myeloid leukemia: a retrospective analysis of 10-year follow-up data

The long-term outcomes of allogeneic hematopoietic cell transplantation (HCT) with reduced-intensity conditioning (RIC) remain inconclusive. To address this issue, we conducted a nationwide registry-based study of patients with acute myeloid leukemia (AML) age 50 years or older who underwent allogeneic HCT in complete remission using RIC (n = 284) or myeloablative conditioning (MAC, n = 190) between 2002 and 2007. The median follow-up period for surviving patients was 10.1 years for RIC recipients and 10.4 years for MAC recipients. The 10-year probabilities of overall survival, relapse, and non-relapse mortality were 36.4%, 30.0%, and 35.7% for RIC recipients, and 39.8%, 26.3%, and 35.5% for MAC recipients, respectively. Multivariate analysis revealed that the conditioning intensity did not affect overall mortality (P = 0.184), relapse (P = 0.904), or non-relapse mortality (P = 0.387). For the 218 patients qualifying for propensity score-matched pairing (109 pairs), RIC was found to be associated with similar survival (P = 0.095) and relapse (P = 0.467), and significantly lower non-relapse mortality (P = 0.046) compared with MAC. Our results confirm the long-term efficacy of RIC allogeneic HCT for older patients with AML and mitigate concerns over an increase in late relapse.

Reduced dose of MTX for GVHD prophylaxis promotes engraftment and decreases non-relapse mortality in umbilical cord blood transplantation

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.

Umbilical Cord Blood Transplants: Current Status and Evolving Therapies

Hematopoietic cell transplants using stem cells from umbilical cord blood are used worldwide for the treatment of malignant and non-malignant disorders. Transplant procedures from this stem cell source have shown promising outcomes in successfully treating various hematologic, immunologic, malignant, and inherited metabolic disorders. Rapid availability of these stem cells is an important advantage over other unrelated donor transplants, especially in situations where waiting can adversely affect the prognosis. The umbilical cord blood is rich in CD34+ stem cells, though with a limited cell dose and usually takes longer to engraft. Limitations around this have been addressed by in vivo and ex vivo expansion techniques as well as enhanced engraftment kinetics. Development of adoptive immunotherapy using other components of umbilical cord blood such as regulatory T cells, virus-specific T cells, and natural killer cells has further transformed the field and enhanced the utility of umbilical cord blood unit.

Evaluation of Cord Blood Total Nucleated and CD34+ Cell Content, Cell Dose, and 8-Allele HLA Match by Patient Ancestry

How cord blood (CB) CD34⁺ cell content and dose and 8-allele HLA match vary by patient ancestry is unknown. We analyzed cell content, dose, and high-resolution HLA-match of units selected for CB transplantation (CBT) by recipient ancestry. Of 544 units (286 infused, 258 next-best backups) chosen for 144 racially diverse adult patients (median weight, 81 kg), the median total nucleated cell (TNC) and CD34⁺cell ⁺contents were higher for Europeans than for non-Europeans: 216 × 10⁷versus 197 × 10⁷ (P = .002) and 160 × 10⁵ versus 132 × 10⁵ (P = .007), respectively. There were marked cell content disparities among ancestry groups, with units selected for Africans having the lowest TNC (189 × 10⁷) and CD34⁺ cell (122 × 10⁵) contents. Units for non-Europeans were also more HLA-mismatched (P = .017). When only the 286 transplanted units were analyzed, the adverse effect of reduced cell content was exacerbated by the higher weights in some groups. For example, northwestern Europeans (high patient weight, high unit cell content) had the best-dosed units, and Africans (high weight, low unit cell content) had the lowest. In Asians, low cell content was partially compensated for by lower weight. Marked differences in 8-allele HLA-match distribution were also observed by ancestry group; for example, 23% of units for northwestern Europeans were 3/8 to 4/8 HLA-matched, compared with 40% for southern Europeans, 46% for white Hispanics, and 51% for Africans. During the study period, 20 additional patients (17 non-Europeans; median weight, 98 kg) did not undergo CBT owing to the lack of a suitable graft. CB extends transplantation access to most patients, but racial disparities exist in cell content, dose, and HLA match.

Time-Varying Effects of Graft Type on Outcomes for Patients with Acute Myeloid Leukemia Undergoing Allogeneic Hematopoietic Cell Transplantation

This study aimed to investigate time-varying effects of graft type on outcomes for patients with acute myeloid leukemia undergoing allogeneic hematopoietic cell transplant. For this purpose we analyzed 3952 patients, 720 of whom underwent matched related bone marrow transplantation (BMT), 1004 matched related peripheral blood stem cell transplantation (PBSCT), 856 matched unrelated BMT, and 1372 umbilical cord blood transplantation (UCBT) during complete remission. The 4-year relapse-free survival (RFS) rates were 59.1%, 52.8%, 59.5%, and 50.6%, respectively. Compared with related BMT, related PBSCT, unrelated BMT, and UCBT were associated with higher risk of nonrelapse mortality and unrelated BMT and UCBT with lower risk of relapse. As a result, both RFS and overall survival were comparable between related BMT and unrelated BMT but were worse for related PBSCT and UCBT than for related BMT. Adverse impact of UCBT was observed only during the early phase of transplant, whereas that of related PBSCT continued even after 2 years post-transplant. Our findings raise concerns about the increased risk of late nonrelapse mortality with the use of PBSC grafts and suggest that related BMT is preferable to related PBSCT; matched unrelated BMT is the next choice in the absence of a matched related donor.