Reduced-intensity conditioning transplantation in acute leukemia: the effect of source of unrelated donor stem cells on outcomes

Blood components utilization in hematopoietic stem cell transplantation: Thirteen-year analysis from an apex oncology center of India

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment modality for a range of hematological disorders including malignancies. The increasing volumes of HSCTs impact transfusion services and the requirement of blood products vary depending on the primary disease, type and phase of transplant, and the HSCT donor type.

MATERIALS AND METHODS

This study analyzed the factors affecting blood component requirements in patients undergoing HSCT. The authors studied the transfusion requirement of packed red blood cells (PRBC) and platelets (PLT) up to 100 days post-transplant among 617 adult patients undergoing HSCT during the study period (2007-2019).

RESULTS

Requirement of PRBC and PLT was significantly higher (P < 0.05) in allogenic HSCT cases across all three phases of transplant compared to autologous HSCT. Unlike PRBC requirement, the PLT requirement was significantly higher during peri-transplant period for haploidentical HSCT and major ABO-incompatible HSCT group compared to matched related donor HSCT and ABO identical HSCT, respectively. In subset analysis based on diagnosis with leukemia as reference, the multiple myeloma group required less while the anemia group required more PRBC and PLT transfusions. The leukemia group required more PRBC than lymphoma group, while the PLT requirement was vice-versa.

CONCLUSION

Factors such as allogeneic HSCT, haploidentical donor type, major ABO-incompatible HSCT, and primary diagnosis as leukemia or anemia were the predictors for increased need of blood products. As higher transfusion requirements may translate into increased costs of treatment, a study like this can help in managing blood component inventory and planning treatment costs of a HSCT program.

An Optimized Search Prognosis Tool to Predict 8/8 HLA Allele-Matched Unrelated Donor Procurement

For patients in need of allogeneic transplantation who lack an HLA-identical sibling, an 8/8 HLA allele-matched unrelated donor (URD) is a standard alternative. However, delays in URD procurement can adversely impact patient care. Recipient genotype and search assessment (MSKv1.0)-based tools can predict search prognosis for many, but both tools have lower performance in non-European ancestry patients. Using the MSKv1.0 tool, we analyzed searches from 1530 potential allograft recipients (including 863 who underwent transplantation) with the aim of creating an optimized MSKv2.0 search prognosis tool that can classify a URD search as either Good or Poor with a high level of accuracy while also limiting an ambiguous Fair search prognosis regardless of patient ancestry. By MSKv2.0, the 8/8 URD search prognosis distribution was 57% Good, 21% Fair, and 22% Poor in Europeans and 15% Good, 21% Fair, and 63% Poor in non-Europeans. Importantly, compared to MSKv1.0, the likelihood of Fair categorization was reduced to <25% with comparable Fair rates (P = .847) in both European and non-European groups. Moreover, all patients with an MSKv2.0 Good prognosis had an 8/8 URD identified, and almost all of those who underwent transplantation had an 8/8 URD (Europeans, 99%; non-Europeans, 98%; P = .504). The MSKv2.0 tool also was highly accurate at classifying Poor searches, with <10% identifying an 8/8 URD, and almost all patients who underwent transplantation (Europeans, 95%; non-Europeans, 96%) receiving an alternative donor. Using preliminary search results, MSKv2.0 accurately classifies patients by likelihood of 8/8 URD procurement, greatly facilitating triage to 8/8 URD (Good prognosis) or alternative donor (Poor prognosis) transplantations.

NCCN Guidelines® Insights: Hematopoietic Cell Transplantation, Version 3.2022

The NCCN Guidelines for Hematopoietic Cell Transplantation (HCT) provide an evidence- and consensus-based approach for the use of autologous and allogeneic HCT in the management of malignant diseases in adult patients. HCT is a potentially curative treatment option for patients with certain types of malignancies; however, recurrent malignancy and transplant-related complications often limit the long-term survival of HCT recipients. The purpose of these guidelines is to provide guidance regarding aspects of HCT, including pretransplant recipient evaluation, hematopoietic cell mobilization, and treatment of graft-versus-host disease-a major complication of allogeneic HCT-to enable the patient and clinician to assess management options in the context of an individual patient's condition. These NCCN Guidelines Insights provide a summary of the important recent updates to the NCCN Guidelines for HCT, including the incorporation of a newly developed section on the Principles of Conditioning for HCT.

Unrelated cord blood transplantation vs. HLA-matched sibling transplantation for adults with B-cell acute lymphoblastic leukemia in complete remission: superior OS for patients with long-term survival

Background

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an important curative therapy for adult acute lymphoblastic leukemia (ALL). For patients who lack a human leukocyte antigen (HLA)-matched sibling donor, unrelated cord blood (UCB) is an alternative graft option. Previous studies have focused mainly on all T- and B-cell ALL (B-ALL) patients, while data related specifically to adult B-ALL patients after UCB transplantation (UCBT) are scarce.

Methods

We retrospectively compared the outcomes of UCBT and HLA-matched sibling transplantation (MST) in the treatment of adult B-ALL patients in complete remission (CR) at our center. From June 2006 to December 2020, 156 adult B-ALL patients who achieved CR before transplantation were enrolled. The main clinical outcomes of UCBT and MST were analyzed.

Results

Hematopoietic recovery was significantly faster in MST recipients than in UCBT recipients. Higher incidences of grades II-IV and III-IV acute graft-versus host disease (aGVHD) were found in UCBT recipients (P < 0.001 and = 0.03), while a lower incidence of extensive chronic GVHD (cGVHD) was found in UCBT recipients (P < 0.001). The cumulative incidences of 2-year non-relapse mortality (NRM), 2-year relapse, 5-year disease-free survival (DFS) and 5-year GVHD-free relapse-free survival (GRFS) were comparable between MST and UCBT recipients. The overall survival (OS) during the first 700 days was similar between the MST and UCBT groups, while the OS of patients with a survival time of more than 700 days in the UCBT group was better than that in the MST group according to multivariate analysis (P = 0.03).

Conclusions

Our study shows that when treating adult B-ALL patients in CR, UCBT can achieve comparable effects as MST, may provide superior OS for patients with long-term survival, and should be considered a good alternative.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03186-3.

Allogeneic hematopoietic cell transplantation with cord blood versus mismatched unrelated donor with post-transplant cyclophosphamide in acute myeloid leukemia

BACKGROUND

Allogeneic hematopoietic cell transplantation (allo-HCT) using a mismatched unrelated donor (MMUD) and cord blood transplantation (CBT) are valid alternatives for patients without a fully human leukocyte antigen (HLA)-matched donor. Here, we compared the allo-HCT outcomes of CBT versus single-allele-mismatched MMUD allo-HCT with post-transplant cyclophosphamide (PTCy) in acute myeloid leukemia.

METHODS

Patients who underwent a first CBT without PTCy (N = 902) or allo-HCT from a (HLA 9/10) MMUD with PTCy (N = 280) were included in the study. A multivariate regression analysis was performed for the whole population. A matched-pair analysis was carried out by propensity score-based 1:1 matching of patients (177 pairs) with known cytogenetic risk.

RESULTS

The incidence of grade II-IV and grade III-IV acute graft-versus-host disease (GVHD) at 6 months was 36% versus 32% (p = 0.07) and 15% versus 11% (p = 0.16) for CBT and MMUD cohorts, respectively. CBT was associated with a higher incidence of graft failure (11% vs. 4%, p < 0.01) and higher 2-year non-relapse mortality (NRM) (30% vs. 16%, p < 0.01) compared to MMUD. In the multivariate analysis, CBT was associated with a higher risk of, NRM (HR = 2.09, 95% CI 1.46-2.99, p < 0.0001), and relapse (HR = 1.35, 95% CI 1-1.83, p = 0.05), which resulted in worse leukemia-free survival (LFS) (HR = 1.68, 95% CI 1.34-2.12, p < 0.0001), overall survival (OS) (HR = 1.7, 95% CI 1.33-2.17, p < 0.0001), and GVHD-free, relapse-free survival (GRFS) (HR = 1.49, 95% CI 1.21-1.83, p < 0.0001) compared to MMUD. The risk of grade II-IV acute GVHD (p = 0.052) and chronic GVHD (p = 0.69) did not differ significantly between the cohorts. These results were confirmed in a matched-pair analysis.

CONCLUSIONS

CBT was associated with lower LFS, OS, and GRFS due to higher NRM, compared to MMUD allo-HCT with PTCy. In the absence of a fully matched donor, 9/10 MMUD with PTCy may be preferred over CBT.

Immune Reconstitution after Haploidentical Donor and Umbilical Cord Blood Allogeneic Hematopoietic Cell Transplantation

Allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative therapy for a variety of hematologic diseases. However, this therapeutic platform is limited by an initial period when patients are profoundly immunocompromised. There is gradual immune recovery over time, that varies by transplant platform. Here, we review immune reconstitution after allogeneic HCT with a specific focus on two alternative donor platforms that have dramatically improved access to allogeneic HCT for patients who lack an HLA-matched related or unrelated donor: haploidentical and umbilical cord blood HCT. Despite challenges, interventions are available to mitigate the risks during the immunocompromised period including antimicrobial prophylaxis, modified immune suppression strategies, graft manipulation, and emerging adoptive cell therapies. Such interventions can improve the potential for long-term overall survival after allogeneic HCT.

Impact of donor type on long-term graft-versus-host disease-free/relapse-free survival for adult acute lymphoblastic leukemia in first remission

We assessed the impact of donor type on long-term outcomes of allogeneic hematopoietic cell transplantation (HCT) in 440 consecutive adults with acute lymphoblastic leukemia (ALL) in first complete remission (CR1), particularly focusing on the donor type-specific difference in graft-versus-host disease (GVHD)-free/relapse-free survival (GRFS). Donor sources were matched sibling donor (MSD; n = 199), matched unrelated donor (MUD; n = 110), 1-allele-mismatched unrelated donor (1-MMUD; n = 83), and cord blood (CB; n = 48). Cumulative incidence of severe chronic GVHD was 14.8% for MSD-HCT, 30.1% for MUD-HCT, 9.6% for 1-MMUD-HCT, and 4.2% for CBT, respectively (P < 0.001), while no difference was observed in grade III-IV acute GVHD. After a median follow-up of 58.1 months, cumulative incidence of relapse was 26.1% for MSD-HCT, 27.2% for MUD-HCT, 31.2% for 1-MMUD-HCT, and 7.2% for CBT, respectively (P = 0.042). Disease-free survival and overall survival were comparable among all donor sources. However, GRFS for MSD-HCT, MUD-HCT, 1-MMUD-HCT, and CBT was 33.1%, 14.5%, 42.1%, and 50.3%, respectively (P = 0.001). In multivariate analysis, CBT showed a comparable GRFS to MSD-HCT (HR, 0.78; P = 0.290), while MUD-HCT was associated with a poorer GRFS (HR, 1.53; P = 0.002). Given the encouraging GRFS of CBT, our data suggest that CBT remains a valid option for adult ALL in CR1.

Optimal Donor for African Americans with Hematologic Malignancy: HLA-Haploidentical Relative or Umbilical Cord Blood Transplant

Although hematopoietic cell transplantation from an HLA-matched unrelated donor is potentially curative for hematologic malignancies, survival is lower for African Americans compared with Caucasians. Because only approximately 20% of African Americans will have an HLA-matched unrelated donor, many of these patients undergo HLA-haploidentical relative or umbilical cord blood transplantation. In this study, we analyzed outcomes after HLA-haploidentical related donor (n = 249) and umbilical cord blood (n = 118) transplantations in African American patients with hematologic malignancy between 2008 and 2016. The predominant disease was acute myelogenous leukemia for recipients of both types of donor grafts. The incidences of grade II-IV and III-IV acute graft-versus-host disease were higher after umbilical cord blood transplantation compared with HLA-haploidentical relative transplantation (56% and 29%, respectively, versus 33% and 11%, respectively; P < .0001). The 2-year incidence of transplantation-related mortality adjusted for age and conditioning regimen intensity was higher after umbilical cord blood transplantation compared with HLA-haploidentical related donor transplantation (31% versus 18%; P = .008); however, there were no between-group differences in the 2-year adjusted incidence of relapse (30% versus 34%; P = .51), overall survival (54% versus 57%; P = .66), or disease-free survival (43% versus 47%; P = .46). Our findings show that the use of HLA-haploidentical and umbilical cord blood transplants expands the access to transplantation with comparable leukemia-free and overall survival for African Americans with hematologic malignancies.

Cord blood transplantation for acute leukemia

INTRODUCTION

Umbilical cord blood transplantation (UCBT) is a suitable alternative for patients with acute leukemia (AL) in need of an allograft and who lack an HLA-matched donor. Single-institution and registry studies have shown that, in both children and adults with AL, the outcome of UCBT is comparable to that of matched unrelated donor. At the same time, these studies have highlighted some limitations of UCBT, such as increased early mortality and delayed recovery of both hematopoietic and immune compartment, which hamper a more widespread adoption of this approach.

AREAS COVERED

In this review, we will analyze the current results of UCBT in children and adults with AL, including comparisons with other hematopoietic stem cell sources and transplant strategies. We will also discuss important factors to be considered when selecting UCB units, as well as future strategies to further improve the outcome of UCBT recipients.

EXPERT OPINION

The utilization of UCBT for the treatment of AL patients has decreased in recent years. However, recent clinical data suggesting that UCBT might offer better results in patients with minimal residual disease, as well as innovative strategies to facilitate engraftment, reduce transplant-related mortality, and optimize anti-leukemic activity, may pave the way toward a second youth for use of UCB cells.

Comparison of reduced-intensity/toxicity conditioning regimens for umbilical cord blood transplantation for lymphoid malignancies

To investigate which reduced-intensity conditioning (RIC)/reduced-toxicity conditioning (RTC) is superior for umbilical cord blood transplantation (UCBT) for lymphoid malignancies, we retrospectively compared three widely used RIC/RTC regimens: fludarabine/melphalan/total body irradiation (FM-TBI, n = 524), fludarabine/cyclophosphamide/total body irradiation (FC-TBI, n = 96), and fludarabine/busulfan/total body irradiation or melphalan (FB-based, n = 159). Among patients with acute lymphoblastic leukemia (ALL) (n = 314), there were no differences in overall survival (OS) by conditioning regimen. Among patients with malignant lymphoma (ML) (n = 465), FM-TBI and FC-TBI regimens had similar OS, whereas FB-based regimen had lower OS (hazard ratio [HR], 1.73; P < 0.01) than did FM-TBI regimen due to higher non-relapse mortality (HR, 1.72; P = 0.02). In addition, mycophenolate mofetil-containing GVHD prophylaxis was associated with better OS than methotrexate-containing GVHD prophylaxis among patients who received FM-TBI (HR, 0.65; P = 0.03) and FC-TBI (HR, 0.25; P < 0.01) regimens due to a decreased relapse risk. In summary, our results suggest that all three RIC/RTC regimens have comparable clinical outcomes in ALL, while the FM-TBI or FC-TBI regimens combined with mycophenolate mofetil-containing GVHD prophylaxis is preferable in RIC/RTC-UCBT for ML. Large prospective studies are warranted to confirm these results.

Optimizing cord blood selection

Nowadays a donor can be found for virtually all patients in need of an allogeneic stem cell transplantation, and the decision whether to use a matched or mismatched unrelated donor, an unrelated donor for umbilical cord blood transplantation (UCBT), or a haploidentical donor depends not only on the availability of the donor but also on patient-, disease-, and center-related factors. This paper summarizes the recent criteria in the selection of cord blood unit, including the cell dose requirement and the HLA typing for the optimal donor choice. The main strategies to optimize the results of UCBT, the conditioning regimens, and the use of antithymocyte globulin and the other platforms of graft-versus-host disease prophylaxis are discussed. The paper describes the results of UCBT in children and adults with malignant and nonmalignant diseases and the comparative analysis with other donor type and stem cell sources. Emerging strategies, focusing on the different platforms of ex vivo expansion and the new applications using cord blood stem cell, are also examined.

Unlicensed Umbilical Cord Blood Units Provide a Safe and Effective Graft Source for a Diverse Population: A Study of 2456 Umbilical Cord Blood Recipients

Umbilical cord blood (UCB) transplantation (UCBT) is a curative procedure for patients with hematologic malignancies and genetic disorders and expands access to transplantation for non-Caucasian patients unable to find a fully matched unrelated donor. In 2011, the US Food and Drug Administration required that unrelated UCBT be performed using either licensed UCB or unlicensed UCB under the Investigational New Drug (IND) program. The National Marrow Donor Program manages an IND under which 2456 patients (1499 adults and 957 children, 564 with malignant diseases and 393 with nonmalignant diseases) underwent single or double UCBT between October 2011 and December 2016. The median patient age was 31 years (range, <1 to 81 years), and 50% of children and 36% of adults were non-Caucasian. The median time to neutrophil engraftment (ie, absolute neutrophil count ≥500/mm³) was 22 days for adults, 20 days for pediatric patients with malignant diseases, and 19 days for pediatric patients with nonmalignant diseases, with corresponding rates of engraftment at 42 days of 89%, 88%, and 90%. In these 3 groups of patients, the incidence of acute graft-versus-host disease (GVHD) grade II-IV was 35%, 32%, and 24%; the incidence of chronic GVHD was 24%, 26%, and 24%; and 1-year overall survival (OS) was 57%, 71%, and 79%, respectively. In multivariate analysis, younger age, lower Hematopoietic Cell Transplantation-Specific Comorbidity Index, early-stage chemotherapy-sensitive disease, and higher performance score were predictive of improved OS for adults. In a subset analysis of children with malignancies undergoing single UCBT, the use of either licensed UCB (n = 48) or unlicensed UCB (n = 382) was associated with similar engraftment and survival. The use of unlicensed UCB units is safe and effective and provides an important graft source for a diverse population.

Prospective Phase 2 Study of Umbilical Cord Blood Transplantation in Adult Acute Leukemia and Myelodysplastic Syndrome

Almost comparable transplantation outcomes have been reported with HLA-matched unrelated donor transplantation (UDT) and cord blood transplantation (CBT). We conducted a prospective phase 2 study to assess the efficacy and safety of single-unit myeloablative CBT in adult leukemia and myelodysplastic syndrome. Because the day 180 survival of UDT was approximately 80%, we determined the alternative hypothesis of expected day 180 survival with a successful engraftment rate of 80% and set the null hypothesis of threshold rate at 65%. Sixty-two patients (median age, 37 years) were registered, including 28 with acute myelogenous leukemia, 25 with acute lymphoblastic leukemia, and 9 with myelodysplastic syndrome. Of 61 eligible patients, 52 were successfully engrafted and survived at day 180 (85%; 95% confidence interval, 74% to 93%). Single-unit CBT was judged to be effective because the null hypothesis was rejected (P < .001). Furthermore, neutrophil engraftment was observed in 57 patients (92%); the incidences of grade II-IV acute and chronic graft-versus-host disease were 30% and 32%, respectively; and the cumulative incidences of nonrelapse mortality and relapse at 2 years were 18% and 13%, respectively. The present study showed favorable survival outcomes with single-unit CBT. Therefore, this method may be considered if a well-HLA-matched UDT cannot be obtained.

Application of high-throughput next-generation sequencing for HLA typing of DNA extracted from postprocessing cord blood units

Cord blood has become an acceptable source of hematopoietic stem cells for transplantation. HLA plays a major role in hematopoietic stem cell transplantation (HSCT). Typing of cord blood samples for HLA alleles has been performed based on the serological and molecular methods. However, with the advent of next-generation sequencing technology, HLA typing becomes more accurate and unambiguous (upto intron level). Contamination of cord blood cells with erythropoietic cells poses a challenge in DNA extraction and downstream application. In the present study, DNA extracted from buffy coat of cord blood samples was typed for HLA-A, -B, -C, DRB1, and DQB1 alleles by Illumina miniseq and the sequences were aligned, phased, and mapped by MIA FORA software algorithms. Most frequent alleles found were HLA A*01:01:01 (17%), A*24:02:01 (15.1%), A*11:01:01 (13.6%), B*40:06:01 (10.7%), C*06:02:01 (17.7%), C*04:01:01 (14.2%), C*15:02:01 (11.4%), C*07:02:01 (10.7%), DRB1*07:01:01 (15.9%), DRB1*10:01:01 (10.2%), DQB1*06:01:01 (17.4%), DQB1*05:01:01 (12.4%), and DQB1*05:03:01 (10.4%). One null allele (A*24:11N), two novel alleles in B loci and three rare alleles (B*40:06:04, B*51:01:05, and C*01:44) were also identified in the present study. This study shows that high-throughput, unambiguous (third-field resolution) HLA typing can be performed on cord blood samples. In order to preserve the precious sample for future use, minimal amount of cord blood samples (postprocessing) could be used for HLA typing purpose.

Delayed immune reconstitution after allogeneic transplantation increases the risks of mortality and chronic GVHD

Slow immune reconstitution is a major obstacle to the successful use of allogeneic hematopoietic cell transplantation (allo-HCT). As matched sibling donor (MSD) allo-HCT is regarded as the gold standard, we evaluated the pace of immune reconstitution in 157 adult recipients of reduced-intensity conditioning followed by MSD peripheral blood HCT (n = 68) and compared these to recipients of umbilical cord blood (UCB; n = 89). At day 28, UCB recipients had fewer natural killer (NK) cells than MSD recipients, but thereafter, NK cell numbers (and their subsets) were higher in UCB recipients. During the first 6 months to 1 year after transplant, UCB recipients had slower T-cell subset recovery, with lower numbers of CD3⁺, CD8⁺, CD8⁺ naive, CD4⁺ naive, CD4⁺ effector memory T, regulatory T, and CD3⁺CD56⁺ T cells than MSD recipients. Notably, B-cell numbers were higher in UCB recipients from day 60 to 1 year. Bacterial and viral infections were more frequent in UCB recipients, yet donor type had no influence on treatment-related mortality or survival. Considering all patients at day 28, lower numbers of total CD4⁺ T cells and naive CD4⁺ T cells were significantly associated with increased infection risk, treatment-related mortality, and chronic graft-versus-host disease (GVHD). Patients with these characteristics may benefit from enhanced or prolonged infection surveillance and prophylaxis as well as immune reconstitution-accelerating strategies.

"Worldwide Network for Blood & Marrow Transplantation (WBMT) special article, challenges facing emerging alternate donor registries"

Hematopoietic cell transplantation (HCT) activity is increasing at an unprecedented pace with > 50,000 allogeneic transplants occurring annually worldwide. Establishing a functional HCT donor registry can be very challenging with respect to ethnicities, financial, technical, and geopolitical issues. Extensive planning steps are essential to overcome the expected challenges while establishing the registry, and to maintain its functionality. A few strategies can help move past those challenges and push the development of such registries forward. Authorities involved in HCT donor registry establishment will have to balance the advantages and costs of such a project and accommodate the emerging alternatives such as cord blood or related haploidentical transplants. Miscalculations and incomplete understanding of the various aspects of the process can have tremendous impact on the optimization of a HCT donor registry especially in developing countries. Herein we present some challenges in establishing such a registry and present potential solutions.

Prevention of relapse after allogeneic hematopoietic cell transplantation by donor and cell source selection

Allogeneic hematopoietic cell transplantation (HCT) is the most established form of cancer immunotherapy and has been successfully applied for the treatment and cure of otherwise lethal neoplastic blood disorders. Cancer immune surveillance is mediated to a large extent by alloreactive T and natural killer (NK) cells recognizing genetic differences between patient and donor. Profound insights into the biology of these effector cells has been obtained over recent years and used for the development of innovative strategies for intelligent donor selection, aiming for improved graft-versus-leukemia effect without unmanageable graft-versus-host disease. The cellular composition of the stem cell source plays a major role in modulating these effects. This review summarizes the current state-of the-art of donor selection according to HLA, NK alloreactivity and stem cell source.

Haploidentical transplantation is associated with better overall survival when compared to single cord blood transplantation: an EBMT-Eurocord study of acute leukemia patients conditioned with thiotepa, busulfan, and fludarabine

Background

Thiotepa-busulfan-fludarabine (TBF) is a widely used conditioning regimen in single umbilical cord blood transplantation (SUCBT). More recently, it was introduced in the setting of non-T cell depleted haploidentical stem cell transplantation (NTD-Haplo). Whether TBF based conditioning provides additional benefit in transplantation from a particular alternative donor type remains to be established.

Methods

This was a retrospective study based on an international European registry. We compared outcomes of de-novo acute myeloid leukemia patients in complete remission receiving NTD-Haplo (n = 186) vs. SUCBT (n = 147) following myeloablative conditioning (MAC) with TBF. Median follow-up was 23 months. Treatment groups resembled in baseline characteristics.

Results

SUCBT was associated with delayed engraftment and higher graft failure. In multivariate analysis no statistically significant differences were observed between the two groups in terms of acute or chronic graft-versus-host disease (GvHD) (HR = 1.03, p = 0.92 or HR = 1.86, p = 0.21) and relapse incidence (HR = 0.8, p = 0.65). Non-relapse mortality (NRM) was significantly higher in SUCBT as compared to NTD-Haplo (HR = 2.63, p = 0.001); moreover, SUCBT did worse in terms of overall survival (HR = 2.18, p = 0.002), leukemia-free survival (HR = 1.94, p = 0.007), and GvHD relapse-free survival (HR = 2.38, p = 0.0002).

Conclusions

Our results suggest that TBF-MAC might allow for a potent graft-versus-leukemia, regardless of the alternative donor type. Furthermore, in patients receiving TBF-MAC, survival with NTD-Haplo may be better compared to SUCBT due to decreased NRM.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0655-8) contains supplementary material, which is available to authorized users.

Thiotepa-Based Intensified Reduced-Intensity Conditioning Adult Double-Unit Cord Blood Hematopoietic Stem Cell Transplantation Results in Decreased Relapse Rate and Improved Survival Compared with Transplantation Following Standard Reduced-Intensity Conditioning: A Retrospective Cohort Comparison

The "Minnesota" reduced-intensity conditioning (RIC) cord blood transplantation (CBT) regimen (standard RIC) of fludarabine (Flu) (200 mg/m²), cyclophosphamide (Cy) (50 mg/kg), and 200- or 300-cGy total body irradiation (TBI) is the most published RIC CBT regimen. Though well tolerated, high relapse rates remain a concern with this regimen. Intensification of conditioning may reduce relapse without increasing transplant-related mortality (TRM). We performed a retrospective cohort comparison of outcomes in adult patients who underwent first double-unit CBT with standard RIC as compared with the intensified regimen of Flu 150 mg/m², Cy 50 mg/kg, thiotepa 10 mg/kg, and 400-cGy TBI (intensified RIC). Of the 99 patients studied, 47 received intensified RIC. Acute myelogenous leukemia was the major indication for transplant. The median age at transplant was 67 years (range, 24 to 74 years) and 54 years (range, 25 to 67 years) in standard RIC and intensified RIC, respectively. Median hematopoietic stem cell transplantation comorbidity index was 3 (range, 0 to 5) and 1 (range, 0 to 6) in the standard RIC and intensified RIC groups, respectively. Median follow-up among survivors was 22 months (range, 3.7 to 79 months) following standard RIC and 15 months (range, 2.8 to 36 months) following intensified RIC. The cumulative incidence (CI) of relapse was significantly lower following intensified RIC compared with standard RIC (P = .0013); this finding maintained significance in multivariate analysis (P = .045). TRM was comparable between the 2 groups (P = .99). Overall survival (OS) was significantly improved following intensified RIC as compared with standard RIC (P = .03). Median OS was 17 months following standard RIC versus not reached followed intensified RIC. The CI of grade II to IV acute graft-versus-host disease (GVHD) was significantly higher in the intensified RIC cohort than the standard RIC-cohort (P = .007), while CI of grade III to IV acute GVHD, any chronic GVHD, and moderate-to-severe chronic GVHD was comparable in each cohort (P = .20, P = .21, and P = .61, respectively). This retrospective analysis shows an improvement in OS and decreased relapse without increase in TRM in patients receiving intensified RIC as compared with standard RIC. Our data suggest that consideration of thiotepa-based intensified RIC may improve outcomes in fit, older patients undergoing double-unit CBT.

Reduced-Intensity Allogeneic Transplant for Acute Myeloid Leukemia and Myelodysplastic Syndrome Using Combined CD34-Selected Haploidentical Graft and a Single Umbilical Cord Unit Compared with Matched Unrelated Donor Stem Cells in Older Adults

Haplo/cord transplantation combines an umbilical cord blood (UCB) graft with CD34-selected haploidentical cells and results in rapid hematopoietic recovery followed by durable UCB engraftment. We compared outcomes of transplants in older patients with acute myeloid leukemia (AML) or high-risk myelodysplastic syndromes (MDS) who received either HLA-matched unrelated donor (MUD) cells or haplo/cord grafts. Between 2007 and 2013, 109 adults ages 50 and older underwent similar reduced-intensity conditioning with fludarabine and melphalan and antibody-mediated T cell depletion for AML (n = 83) or high-risk MDS (n = 26) followed by either a MUD (n = 68) or haplo/cord (n = 41) graft. Patient characteristics were similar for each graft source except for more minority patients receiving a haplo/cord transplant (P = .01). One half of the AML patients were not in remission. Two-year progression-free survival (PFS), overall survival (OS), and graft-versus-host disease-free relapse-free survival were 38%, 48%, and 32.1% for MUD and 33%, 48%, and 33.8% for haplo/cord transplants (P = .62 for PFS; P = .97 for OS; P= .84), respectively. Acute grades II to IV and chronic graft-versus-host-disease rates did not differ at 19.5% and 4.9% in haplo/cord compared with 25% and 7.4% after MUD (P = .53 and P = .62, respectively). Multivariate analysis confirmed no significant differences in transplant outcomes by donor type. Haplo/cord reduced-intensity transplantation achieves similar outcomes relative to MUD in older AML and MDS patients, making this a promising option for those without matched donors.

Validation of an Algorithm to Predict the Likelihood of an 8/8 HLA-Matched Unrelated Donor at Search Initiation

A strategy to rapidly determine if a matched unrelated donor (URD) can be secured for allograft recipients is needed. We sought to validate the accuracy of (1) HapLogic match predictions and (2) a resultant novel Search Prognosis (SP) patient categorization that could predict 8/8 HLA-matched URD(s) likelihood at search initiation. Patient prognosis categories at search initiation were correlated with URD confirmatory typing results. HapLogic-based SP categorizations accurately predicted the likelihood of an 8/8 HLA-match in 830 patients (1530 donors tested). Sixty percent of patients had 8/8 URD(s) identified. Patient SP categories (217 very good, 104 good, 178 fair, 33 poor, 153 very poor, 145 futile) were associated with a marked progressive decrease in 8/8 URD identification and transplantation. Very good to good categories were highly predictive of identifying and receiving an 8/8 URD regardless of ancestry. Europeans in fair/poor categories were more likely to identify and receive an 8/8 URD compared with non-Europeans. In all ancestries very poor and futile categories predicted no 8/8 URDs. HapLogic permits URD search results to be predicted once patient HLA typing and ancestry is obtained, dramatically improving search efficiency. Poor, very poor, andfutile searches can be immediately recognized, thereby facilitating prompt pursuit of alternative donors.

Outcomes after Umbilical Cord Blood Transplantation for Myelodysplastic Syndromes

For patients with hematologic malignancies undergoing allogeneic hematopoietic cell transplantation, umbilical cord blood transplantation (UCBT) has become an acceptable alternative donor source in the absence of a matched sibling or unrelated donor. To date, however, there have been few published series dedicated solely to describing the outcomes of adult patients with myelodysplastic syndrome (MDS) who have undergone UCBT. Between 2004 and 2013, 176 adults with MDS underwent UCBT as reported to the Center for International Blood and Marrow Transplant Research. Median age at the time of transplantation was 56 years (range, 18-73 years). The study group included 10% with very low, 23% with low, 19% with intermediate, 19% with high, and 13% with very high-risk Revised International Prognostic Scoring System (IPSS-R) scores. The 100-day probability of grade II-IV acute graft-versus-host disease (GVHD) was 38%, and the 3-year probability of chronic GVHD was 28%. The probabilities of relapse and transplantation-related mortality (TRM) at 3 years were 32% and 40%, respectively, leading to a 3-year disease-free survival (DFS) of 28% and an overall survival (OS) of 31%. In multivariate analysis, increasing IPSS-R score at the time of HCT was associated with inferior TRM (P = .0056), DFS (P = .018), and OS (P = .0082), but not with GVHD or relapse. The presence of pretransplantation comorbidities was associated with TRM (P = .001), DFS (P = .02), and OS (P = .001). Reduced-intensity conditioning was associated with increased risk of relapse (relative risk, 3.95; 95% confidence interval, 1.78-8.75; P < .001), and although a higher proportion of myeloablative UCBTs were performed in patients with high-risk disease, the effect of conditioning regimen intensity was the same regardless of IPSS-R score. For some individuals who lack a matched sibling or unrelated donor, UCBT can result in long-term DFS; however, the success of UCBT in this population is hampered by a high rate of TRM.

Alternative Donor Graft Sources for Adults with Hematologic Malignancies: A Donor for All Patients in 2017!

Hematopoietic stem cell transplant (HSCT) is potentially curative for a wide variety of malignant diseases, including acute and leukemias, lymphoma, and myelodysplasia. Choice of a stem cell donor is dependent on donor availability, donor compatibility and health, recipient disease type, and recipient condition. Current sources of stem cell donation for HSCT are matched sibling donors (MSDs), matched unrelated donors (MUDs), 1-antigen mismatched unrelated donors (MMUDs), haploidentical donors (haplo), and umbilical cord blood (UCB) units. Historically, preferred donors for HSCT have been human leukocyte antigen (HLA)-matched sibling donors; however, only about 30% of U.S. patients will have a MSD available. The majority of patients referred for HSCT will require an alternative donor graft: MUD, MMUD, UCB, or haplo. The likelihood of finding a MUD varies depending on the ethnicity of the recipient. White Caucasians of European descent have the greatest chance of finding a MUD. Chances of finding a MUD are significantly less for African-American or Hispanic recipients due to HLA polymorphisms. Therefore, MMUD, UCB, and haplo donor graft sources expand the donor pool for recipients who do not have a MSD or MUD available. Given the variety of different donor stem cell sources available today, nearly every patient who needs an allogeneic HSCT has a potential donor in 2017. All transplant-eligible patients with hematologic malignancies should be evaluated by a transplant center to determine if HSCT is a viable treatment option for their underlying disease process.

IMPLICATIONS FOR PRACTICE

The goal of this review is to increase the awareness of oncology practitioners to the availability of alternative donor stem cell transplants for patients with hematologic malignancies. Despite new agents, stem cell transplant remains the only curative therapy for many patients with acute and chronic leukemia, myelodysplasia, and lymphoma. Given the variety of different donor stem cell sources available today, nearly every patient who needs an allogeneic stem cell transplant will have a donor.

Ex Vivo Mesenchymal Precursor Cell-Expanded Cord Blood Transplantation after Reduced-Intensity Conditioning Regimens Improves Time to Neutrophil Recovery

We previously showed the safety of using cord blood (CB) expanded ex vivo in cocultures with allogeneic mesenchymal precursor cells (MPC) after myeloablative conditioning with faster recovery of neutrophils and platelets compared with historical controls. Herein, we report the transplantation outcomes of 27 patients with hematologic cancers who received 1 CB unit expanded ex vivo with MPCs in addition to an unmanipulated CB (MPC group) after reduced-intensity conditioning (RIC). The results in this group were compared with 51 historical controls who received 2 unmanipulated CB units (control group). The analyses were stratified for 2 RIC treatment groups: (1) total body irradiation 200 cGy + cyclophosphamide + fludarabine) (TCF), and (2) fludarabine + melphalan  (FM). Coculture of CB with MPCs led to an expansion of total nucleated cells by a median factor of 12 and of CD34⁺ cells by a median factor of 49. In patients in whom engraftment occurred, the median time to neutrophil engraftment was 12 days in the MPC group, as compared with 16 days in controls (P = .02). The faster neutrophil engraftment was observed in both RIC groups. The cumulative incidence of neutrophil engraftment on day 26 was 75% with expansion versus 50% without expansion in patients who received FM as the RIC regimen (P = .03). Incidence of neutrophil engraftment was comparable in MPC and control groups if treated with TCF (82% versus 79%, P = .40). Transplantation of CB units expanded with MPCs is safe and effective with faster neutrophil engraftment even after RIC regimens.

Optimal Practices in Unrelated Donor Cord Blood Transplantation for Hematologic Malignancies

Unrelated donor cord blood transplantation (CBT) results in disease-free survival comparable to that of unrelated adult donor transplantation in patients with hematologic malignancies. Extension of allograft access to racial and ethnic minorities, rapid graft availability, flexibility of transplantation date, and low risks of disabling chronic graft-versus-host disease (GVHD) and relapse are significant advantages of CBT, and multiple series have reported a low risk of late transplantation-related mortality (TRM) post-transplantation. Nonetheless, early post-transplantation morbidity and TRM and the requirement for intensive early post-transplantation management have slowed the adoption of CBT. Targeted care strategies in CBT recipients can mitigate early transplantation complications and reduce transplantation costs. Herein we provide a practical "how to" guide to CBT for hematologic malignancies on behalf of the National Marrow Donor Program and the American Society of Blood and Marrow Transplantation's Cord Blood Special Interest Group. It shares the best practices of 6 experienced US transplantation centers with a special interest in the use of cord blood as a hematopoietic stem cell source. We address donor search and unit selection, unit thaw and infusion, conditioning regimens, immune suppression, management of GVHD, opportunistic infections, and other factors in supportive care appropriate for CBT. Meticulous attention to such details has improved CBT outcomes and will facilitate the success of CBT as a platform for future graft manipulations.

GvHD after umbilical cord blood transplantation for acute leukemia: an analysis of risk factors and effect on outcomes

Using the Center for International Blood and Marrow Transplant Research (CIBMTR) registry, we analyzed 1404 umbilical cord blood transplantation (UCBT) patients (single (<18 years)=810, double (⩾18 years)=594) with acute leukemia to define the incidence of acute GvHD (aGvHD) and chronic GvHD (cGvHD), analyze clinical risk factors and investigate outcomes. After single UCBT, 100-day incidence of grade II-IV aGvHD was 39% (95% confidence interval (CI), 36-43%), grade III-IV aGvHD was 18% (95% CI, 15-20%) and 1-year cGvHD was 27% (95% CI, 24-30%). After double UCBT, 100-day incidence of grade II-IV aGvHD was 45% (95% CI, 41-49%), grade III-IV aGvHD was 22% (95% CI, 19-26%) and 1-year cGvHD was 26% (95% CI, 22-29%). For single UCBT, multivariate analysis showed that absence of antithymocyte globulin (ATG) was associated with aGvHD, whereas prior aGvHD was associated with cGvHD. For double UCBT, absence of ATG and myeloablative conditioning were associated with aGvHD, whereas prior aGvHD predicted for cGvHD. Grade III-IV aGvHD led to worse survival, whereas cGvHD had no significant effect on disease-free or overall survival. GvHD is prevalent after UCBT with severe aGvHD leading to higher mortality. Future research in UCBT should prioritize prevention of GvHD.

Personalized fludarabine dosing to reduce nonrelapse mortality in hematopoietic stem-cell transplant recipients receiving reduced intensity conditioning

Patients undergoing hematopoietic cell transplantation (HCT) with reduced intensity conditioning (RIC) commonly receive fludarabine. Higher exposure of F-ara-A, the active component of fludarabine, has been associated with a greater risk of nonrelapse mortality (NRM). We sought to develop a model for fludarabine dosing in adult HCT recipients that would allow for precise dose targeting and predict adverse clinical outcomes. We developed a pharmacokinetic model from 87 adults undergoing allogeneic RIC HCT that predicts F-ara-A population clearance (Clpop) accounting for ideal body weight and renal function. We then applied the developed model to an independent cohort of 240 patients to identify whether model predictions were associated with NRM and acute graft versus host disease (GVHD). Renal mechanisms accounted for 35.6% of total F-ara-A Clpop. In the independent cohort, the hazard ratio of NRM at day 100 was significantly higher in patients with predicted F-ara-A clearance (Clpred) <8.50 L/h (P < 0.01) and area under the curve (AUCpred) >6.00 μg × h/mL (P = 0.01). A lower Clpred was also associated with more NRM at month 6 (P = 0.01) and trended toward significance at 12 months (P = 0.05). In multivariate analysis, low fludarabine clearance trended toward higher risk of acute GVHD (P = 0.05). We developed a model that predicts an individual's systemic F-ara-A exposure accounting for kidney function and weight. This model may provide guidance in dosing especially in overweight individuals and those with altered kidney function.

Umbilical cord blood cells from unrelated donor as an alternative source of hematopoietic stem cells for transplantation in children and adults

Umbilical cord blood (CB) is an alternative source of hematopoietic stem cells (HSC) for patients requiring allogeneic HSC transplantation but lacking a suitable human leukocyte antigen (HLA)-matched donor. Using CB has many advantages, including lower HLA-matching requirements, increased donor availability, and low rates of graft-versus-host disease. Furthermore, with over 630,000 cryopreserved volunteer CB units currently stored in international CB banks worldwide, CB is rapidly available for those patients requiring urgent transplantation. However, concern remains over the low HSC doses available in CB grafts, resulting in delayed engraftment and poor immune reconstitution. This article reviews the current use and future developments of unrelated allogeneic CB transplantation (CBT). An overview of the encouraging results of CBT and the comparisons with other HSC sources and transplant strategies both in children and adults with malignant and non-malignant diseases are shown. We will discuss important factors that need to be considered when selecting CB units for transplantation to further improve the results of CBT.

Haploidentical cord transplantation-The best of both worlds

Haploidentical (haplo)-cord transplantation combines infusion of an umbilical cord blood (UCB) unit with CD34-selected cells usually from human leukocyte antigen (HLA) mismatched donors. Initial rapid count recovery from the haplo-hematopoietic progenitors, is gradually replaced by durable engraftment from UCB progenitors. UCB grafts used for haplo-cord are smaller, but better matched than those required for single or double UCB stem cell transplant (SCT). More than 200 patients with hematological malignancies have been transplanted. Median age was 54 years (range 17-74) and 77 were over age 60. One-year survival was 64% for patients with intermediate- and low-risk disease, with no deaths beyond 2 years. In high-risk disease, 1-year survival was 44%. In a comparison with patients undergoing double UCB SCT, haplo-cord transplant resulted in faster hematopoietic recovery, lower rates of acute and chronic graft-versus-host disease (GVHD), lower rates of disease recurrence, and improved GVHD- and relapse-free survival (GRFS). Excellent results were also reported for patients with aplastic anemia where 18 of 21 patients had sustained cord blood engraftment. Rates of GVHD and of disease recurrence after haplo-cord are encouraging. However, in the approximately 10% of patients with failure of the UCB graft disease recurrence is high, supporting the important role of UCB-mediated graft-versus-leukemia (GVL). Ongoing efforts are aimed at identifying determinants of UCB engraftment, at reducing rates of disease recurrence in high risk patients and at optimizing dose and schedule of ATG -necessary to avoid early haplo-graft rejection, but also contributing to early post-transplant immunocompromise. For those lacking haploidentical donors, unrelated donors have been successfully utilized.

Higher Early Monocyte and Total Lymphocyte Counts Are Associated with Better Overall Survival after Standard Total Body Irradiation, Cyclophosphamide, and Fludarabine Reduced-Intensity Conditioning Double Umbilical Cord Blood Allogeneic Stem Cell Transplantation in Adults

This single-center retrospective study aimed to report the impact of early hematopoietic and immune recoveries after a standard total body irradiation, cyclophosphamide, and fludarabine (TCF) reduced-intensity conditioning (RIC) regimen for double umbilical cord blood (dUCB) allogeneic stem cell transplantation (allo-SCT) in adults. We analyzed 47 consecutive patients older than 17 years who engrafted after a dUCB TCF allo-SCT performed between January 2006 and April 2013 in our department. Median times for neutrophil and platelet recoveries were 17 (range, 6 to 59) and 37 days (range, 0 to 164), respectively. The 3-year overall (OS) and disease-free survivals, relapse incidence, and nonrelapse mortality were 65.7%, 57.2%, 27.1%, and 19%, respectively. In multivariate analysis, higher day +30 monocyte (≥615/mm(3); hazard ratio [HR], .04; 95% confidence interval [CI], .004 to .36; P < .01) and day +42 lymphocyte (≥395/mm(3); HR, .16; 95% CI, .03 to .78; P = .02) counts were independently associated with better OS. These results suggest that early higher hematopoietic and immune recovery is predictive of survival after dUCB TCF RIC allo-SCT in adults. Factors other than granulocyte colony-stimulating factor, which was used in all cases, favoring expansion of monocytes or lymphocytes, should be tested in the future as part of the UCB transplantation procedure.

Reduced intensity haplo plus single cord transplant compared to double cord transplant: improved engraftment and graft-versus-host disease-free, relapse-free survival

Umbilical cord blood stem cell transplants are commonly used in adults lacking HLA-identical donors. Delays in hematopoietic recovery contribute to mortality and morbidity. To hasten recovery, we used co-infusion of progenitor cells from a partially matched related donor and from an umbilical cord blood graft (haplo-cord transplant). Here we compared the outcomes of haplo-cord and double-cord transplants. A total of 97 adults underwent reduced intensity conditioning followed by haplo-cord transplant and 193 patients received reduced intensity conditioning followed by double umbilical cord blood transplantation. Patients in the haplo-cord group were more often from minority groups and had more advanced malignancy. Haplo-cord recipients received fludarabine-melphalan-anti-thymocyte globulin. Double umbilical cord blood recipients received fludarabine-cyclophosphamide and low-dose total body irradiation. In a multivariate analysis, haplo-cord had faster neutrophil (HR=1.42, P=0.007) and platelet (HR=2.54, P<0.0001) recovery, lower risk of grade II-IV acute graft-versus-host disease (HR=0.26, P<0.0001) and chronic graft-versus-host disease (HR=0.06, P<0.0001). Haplo-cord was associated with decreased risk of relapse (HR 0.48, P=0.001). Graft-versus-host disease-free, relapse-free survival was superior with haplo-cord (HR 0.63, P=0.002) but not overall survival (HR=0.97, P=0.85). Haplo-cord transplantation using fludarabine-melphalan-thymoglobulin conditioning hastens hematopoietic recovery with a lower risk of relapse relative to double umbilical cord blood transplantation using the commonly used fludarabine-cyclophosphamide-low-dose total body irradiation conditioning. Graft-versus-host disease-free and relapse-free survival is significantly improved. Haplo-cord is a readily available graft source that improves outcomes and access to transplant for those lacking HLA-matched donors. Trials registered at clinicaltrials.gov identifiers 00943800 and 01810588.

Alternative donors: cord blood for adults

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for patients with hematological diseases. The probability of finding a human leukocyte antigen (HLA)- identical donor among family members is around 25% and 30% that of having a full matched unrelated donor in the registry. Patients in need may also benefit of a HLA-mismatched HSCT either from an haploidentical donors or from umbilical cord blood (UCB). Much has been learned about UCB transplant (UCBT) since the first human UCBT was performed back in 1988. Cord blood banks have been established worldwide for the collection, cryopreservation, and distribution of UCB for HSCT. Today, a global network of cord blood banks and transplant centers has been established with a large common inventory of more than 650,000 UCB units available, allowing for more than 40,000 UCBT worldwide in children and adults with severe hematological diseases. Several studies have been published on UCBT, assessing risk factors such as cell dose and HLA mismatch. Outcomes of several retrospective comparative studies showed similar results using other stem cell sources both in pediatric and adult setting. New strategies are ongoing to facilitate engraftment and reduce transplant-related mortality. In this issue, we review the current results of UCBT in adults with hematological malignancies and the clinical studies comparing UCBT with other transplant strategies. We provide guidelines for donor algorithm selection in UCBT setting.

Cord blood transplant for acute myeloid leukaemia

Umbilical cord blood is a haematopoietic progenitor cell source for patients with acute myeloid leukaemia (AML), other haematological malignancies and metabolic diseases who can be cured by allogeneic haematopoietic cell transplantation, but who do not have a human leucocyte antigen compatible related or unrelated donor. Although the first cord blood transplants were done in children, there are currently more cord blood transplants performed in adults. In this review, we explore the history of umbilical cord blood transplantation, paediatric and adult outcome results, and novel trends to improve engraftment and reduce infection. Umbilical cord blood transplantation cures approximately 30-40% of adults and 60-70% of children with AML. Controversial issues, including the use of double versus single cord blood units for transplantation, optimal cord blood unit selection, infection prophylaxis, conditioning regimens and graft versus host disease prophylaxis, will be reviewed. Finally, comparison to other graft sources, cost, access to care, and the ideal graft source are discussed.

Hematopoietic stem cell transplantation for patients with AML in first complete remission

Postremission therapy in patients with acute myeloid leukemia (AML) may consist of continuing chemotherapy or transplantation using either autologous or allogeneic stem cells. Patients with favorable subtypes of AML generally receive chemotherapeutic consolidation, although recent studies have also suggested favorable outcome after hematopoietic stem cell transplantation (HSCT). Although allogeneic HSCT (alloHSCT) is considered the preferred type of postremission therapy in poor- and very-poor-risk AML, the place of alloHSCT in intermediate-risk AML is being debated, and autologous HSCT is considered a valuable alternative that may be preferred in patients without minimal residual disease after induction chemotherapy. Here, we review postremission transplantation strategies using either autologous or allogeneic stem cells. Recent developments in the field of alternative donors, including cord blood and haploidentical donors, are highlighted, and we discuss reduced-intensity alloHSCT in older AML recipients who represent the predominant category of patients with AML who have a high risk of relapse in first remission.

Novel Techniques for Ex Vivo Expansion of Cord Blood: Clinical Trials

Cord blood (CB) provides an excellent alternative source of hematopoietic progenitor cells (HPC) for patients lacking human leukocyte antigen-matched peripheral blood or bone marrow graft for transplantation. However, due to the limited cell dose in CB graft, it is associated with prolonged time to engraftment, risk of graft rejection, infections, and treatment-related mortality. To increase the cell dose, a variety of ex vivo expansion techniques have been developed. Results of traditional methods of CB expansion using cytokines alone were disappointing. Expanding CB cells with mesenchymal progenitor cells led to sizeable increase in graft content and improved engraftment. Other methods used HPC-differentiation blockers, such as nicotinamide analogs, copper chelators, inducing constitutive Notch signaling, or an aryl hydrocarbon receptor antagonist (StemReginin1). Many of these methods lead to substantial expansions of total nucleated cells and CD34(+) cells, and significantly improved time to neutrophil or platelet engraftment in patients transplanted with the expanded products compared to the recipients of unmanipulated CBT. These studies differ not only in the expansion method but also with regards to the cytokines used, patient population, conditioning regimens, and transplantation practices, to name a few. Some of these methods employed expansion of a portion of CB unit in the setting of single CBT, while others in the setting of double CBT. Here, we review various procedures used for CB expansion and highlight some of the key differences. Novel methods of improving engraftment that aim at improving bone marrow homing potential of CB cells are not reviewed.

Use of alternative donors for allogeneic stem cell transplantation

For patients without a human leukocyte antigen (HLA)-matched sibling or unrelated donor, options include transplantation from HLA-mismatched related donors, HLA-mismatched unrelated donors, or unrelated cord blood units. Graft failure remains a problem in 10%-20% of cord blood transplants that contain a limited number of hematopoietic cells. Many approaches are tested in clinical trials to offset the risk of graft failure after cord blood transplantation. GVHD remains a hurdle with any HLA mismatched graft. The use of post-transplant cyclophosphamide holds the promise to overcome the HLA barrier and prevent GVHD despite donor mismatch for a full HLA haplotype. Priority should be given to enrolling patients onto transplant protocols addressing the fundamental problems of engraftment, GVHD, relapse or treatment-related mortality tested with one or more of the alternative stem cell sources. Principles for prioritization of alternative stem cell sources are discussed separately for children and adults who cannot be enrolled on clinical trials. It is difficult ranking currently available sources in the face of multiple factors affecting outcomes, rapidly changing transplant technology and without results from comparative trials.

High Disease-Free Survival with Enhanced Protection against Relapse after Double-Unit Cord Blood Transplantation When Compared with T Cell-Depleted Unrelated Donor Transplantation in Patients with Acute Leukemia and Chronic Myelogenous Leukemia

Double-unit cord blood (DCB) grafts are a rapidly available stem cell source for adults with high-risk leukemias. However, how disease-free survival (DFS) after DCB transplantation (DCBT) compares to that of unrelated donor transplantation (URDT) is not fully established. We analyzed 166 allograft recipients (66 8/8 HLA-matched URDT, 45 7/8 HLA-matched URDT, and 55 DCBT) ages 16 to 60 years with high-risk acute leukemia or chronic myelogenous leukemia (CML). URDT and DCBT recipients were similar except DCBT recipients were more likely to have lower weight and non-European ancestry and to receive intermediate-intensity conditioning. All URDT recipients received a CD34(+) cell-selected (T cell-depleted) graft. Overall, differences between the 3-year transplantation-related mortality were not significant (8/8 URDT, 18%; 7/8 URDT, 39%; and DCBT, 24%; P = .108), whereas the 3-year relapse risk was decreased after DCBT (8/8 URDT, 23%; 7/8 URDT, 20%; and DCBT 9%, P = .037). Three-year DFS was 57% in 8/8 URDT, 41% in 7/8 URDT, and 68% in DCBT recipients (P = .068), and the 3-year DFS in DCBT recipients was higher than that of 7/8 URDT recipients (P = .021). In multivariate analysis in acute leukemia patients, factors adversely associated with DFS were female gender (hazard ratio [HR], 1.68; P = .031), diagnosis of acute lymphoblastic leukemia (HR, 2.09; P = .004), and 7/8 T cell-depleted URDT (HR, 1.91; P = .037). High DFS can be achieved in adults with acute leukemia and CML with low relapse rates after DCBT. Our findings support performing DCBT in adults in preference to HLA-mismatched T cell-depleted URDT and suggest DCBT is a readily available alternative to T cell-depleted 8/8 URDT, especially in patients requiring urgent transplantation.

Impact of the source of hematopoietic stem cell in unrelated transplants: comparison between 10/10, 9/10-HLA matched donors and cord blood

In absence of available matched-related or unrelated donor (MUD), mismatched unrelated donors (MMUD) and unrelated cord blood (UCB) are both considered to be suitable donors, with similar post-transplant overall survival. In most of these retrospective comparisons, HLA typing of adult donors was performed at eight loci. The aim of this study was to compare the outcome of patients transplanted from UCB (N = 64) with those transplanted from 9/10-HLA MMUD (N = 84) or 10/10-HLA MUD (N = 196). In multivariate analysis, UCB was associated with less Grade II-IV acute GVHD in comparison with MUD (aHR 1.97, 95% CI 1.19-3.27, P = 0.009) and MMUD transplants (aHR 1.79, 95% CI 1.02-3.15, P = 0.042), while the cumulative incidence of chronic GVHD was not significantly different between the three groups. Overall survival (OS), non-relapse mortality, and relapse were not different between MMUD and UCB transplantation, whereas OS was impaired after UCB in comparison with MUD (aHR 0.65, 95% CI 0.43-0.99, P = 0.043). Factors also impacting OS were the donor/recipient CMV serostatus (Donor-/Recipient+ aHR 1.76, 95% CI 1.23-2.52, P = 0.002 compared with D-/R-), the donor/recipient gender combination (Female/Male versus other combinations aHR 1.57, 95% CI 1.11-2.22, P = 0.012) and disease risk (aHR 1.58, 95% CI 1.05-2.38, P = 0.027 for high vs. low risk disease). Our data confirm that UCB and 9/10-HLA MMUD are both relevant alternative options when no 10/10-HLA donor is available. Donor/recipient gender combination and CMV serostatus had a significant impact on survival and may be taken into account, along with donor type, in the setting of MMUD and UCB transplants.

Better allele-level matching improves transplant-related mortality after double cord blood transplantation

Cord blood transplant requires less stringent human leukocyte antigen matching than unrelated donors. In 133 patients with hematologic malignancies who engrafted after double cord blood transplantation with a dominant unit, we studied the effect of high resolution testing at 4 loci (-A, -B, -C, -DRB1) for its impact on 2-year transplant-related mortality. Ten percent of the dominant cord blood units were matched at 7-8/8 alleles using HLA-A, -B, -C, and -DRB1; 25% were matched at 6/8, 40% at 5/8, and 25% at 4/8 or less allele. High resolution typing at 4 loci showed that there was no 2-year transplant-related mortality in 7-8/8 matched patients. Patients with 5-6/8 matched dominant cord blood units had 2-year transplant-related mortality of 39% while patients with 4/8 or less matched units had 60%. Multivariate regression analyses confirmed the independent effect of high resolution typing on the outcome when adjusted for age, diagnosis, CD34(+) cell dose infused, graft manipulation and cord to cord matching. The worst prognostic group included patients aged over 32 years with 4/8 or less matched cord blood units compared with patients who were either younger than 32 years old independent of allele-level matching, or aged over 32 years but with 5-6/8 matched cord blood units (Hazard Ratio 2.2; 95% confidence interval: 1.3-3.7; P<0.001). Patients with 7-8/8 matched units remained the group with the best prognosis. Our data suggest that high resolution typing at 4 loci and selecting cord blood units matched at at least 5/8 alleles may reduce transplant-related mortality after double cord blood transplantation.

Haploidentical transplant with posttransplant cyclophosphamide vs matched unrelated donor transplant for acute myeloid leukemia

We studied adults with acute myeloid leukemia (AML) after haploidentical (n = 192) and 8/8 HLA-matched unrelated donor (n = 1982) transplantation. Haploidentical recipients received calcineurin inhibitor (CNI), mycophenolate, and posttransplant cyclophosphamide for graft-versus-host disease (GVHD) prophylaxis; 104 patients received myeloablative and 88 received reduced intensity conditioning regimens. Matched unrelated donor transplant recipients received CNI with mycophenolate or methotrexate for GVHD prophylaxis; 1245 patients received myeloablative and 737 received reduced intensity conditioning regimens. In the myeloablative setting, day 30 neutrophil recovery was lower after haploidentical compared with matched unrelated donor transplants (90% vs 97%, P = .02). Corresponding rates after reduced intensity conditioning transplants were 93% and 96% (P = .25). In the myeloablative setting, 3-month acute grade 2-4 (16% vs 33%, P < .0001) and 3-year chronic GVHD (30% vs 53%, P < .0001) were lower after haploidentical compared with matched unrelated donor transplants. Similar differences were observed after reduced intensity conditioning transplants, 19% vs 28% (P = .05) and 34% vs 52% (P = .002). Among patients receiving myeloablative regimens, 3-year probabilities of overall survival were 45% (95% CI, 36-54) and 50% (95% CI, 47-53) after haploidentical and matched unrelated donor transplants (P = .38). Corresponding rates after reduced intensity conditioning transplants were 46% (95% CI, 35-56) and 44% (95% CI, 0.40-47) (P = .71). Although statistical power is limited, these data suggests that survival for patients with AML after haploidentical transplantation with posttransplant cyclophosphamide is comparable with matched unrelated donor transplantation.

Alternative Donor Transplantation for Acute Myeloid Leukemia

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapy for adult patients with acute myeloid leukemia (AML), but its use for consolidation therapy after first remission with induction chemotherapy used to be limited to younger patients and those with suitable donors. The median age of AML diagnosis is in the late 60s. With the introduction of reduced-intensity conditioning (RIC), many older adults are now eligible to receive allo-HCT, including those who are medically less fit to receive myeloablative conditioning. Furthermore, AML patients commonly have no human leukocyte antigen (HLA)-identical or medically suitable sibling donor available to proceed with allo-HCT. Technical advances in donor matching, suppression of alloreactivity, and supportive care have made it possible to use alternative donors, such as unrelated umbilical cord blood (UCB) and partially HLA-matched related (haploidentical) donors. Outcomes after alternative donor allo-HCT are now approaching the outcomes observed for conventional allo-HCT with matched related and unrelated donors. Thus, with both UCB and haploidentical donors available, lack of donor should rarely be a limiting factor in offering an allo-HCT to adults with AML.

Umbilical cord blood donation: public or private?

Umbilical cord blood (UCB) is a graft source for patients with malignant or genetic diseases who can be cured by allogeneic hematopoietic cell transplantation (HCT), but who do not have an appropriately HLA-matched family or volunteer unrelated adult donor. Starting in the 1990s, unrelated UCB banks were established, accepting donations from term deliveries and storing UCB units for public use. An estimated 730 000 UCB units have been donated and stored to date and ~35 000 UCB transplants have been performed worldwide. Over the past 20 years, private and family banks have grown rapidly, storing ~4 million UCB units for a particular patient or family, usually charging an up-front and yearly storage fee; therefore, these banks are able to be financially sustainable without releasing UCB units. Private banks are not obligated to fulfill the same regulatory requirements of the public banks. The public banks have released ~30 times more UCB units for therapy. Some countries have transitioned to an integrated banking model, a hybrid of public and family banking. Today, pregnant women, their families, obstetrical providers and pediatricians are faced with multiple choices about the disposition of their newborn's cord blood. In this commentary, we review the progress of UCB banking technology; we also analyze the current data on pediatric and adult unrelated UCB, including the recent expansion of interest in transplantation for hemoglobinopathies, and discuss emerging studies on the use of autologous UCB for neurologic diseases and regenerative medicine. We will review worldwide approaches to UCB banking, ethical considerations, criteria for public and family banking, integrated banking ideas and future strategies for UCB banking.

Outcomes of Cord Blood Transplantation Using Reduced-Intensity Conditioning for Chronic Lymphocytic Leukemia: A Study on Behalf of Eurocord and Cord Blood Committee of Cellular Therapy and Immunobiology Working Party, Chronic Malignancies Working Party of the European Society for Blood and Marrow Transplantation, and the Societé Française de Greffe de Moelle et Therapie Cellulaire

Outcomes after umbilical cord blood transplantation (UCBT) for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) are unknown. We analyzed outcomes of 68 patients with poor-risk CLL/SLL who underwent reduced-intensity (RIC) UCBT from 2004 to 2012. The median age was 57 years and median follow-up 36 months; 17 patients had del 17p/p53mutation, 19 patients had fludarabine-refractory disease, 11 relapsed after autologous stem cell transplantation, 8 had diagnosis of prolymphocytic leukemia, 4 had Richter syndrome, and 8 underwent transplantation with progressive or refractory disease. The most common RIC used was cyclophosphamide, fludarabine, and total body irradiation (TBI) in 82%; 15 patients received antithymocyte globulin. Most of the cord blood grafts were HLA mismatched and 76% received a double UCBT. Median total nucleated cells collected was 4.7 × 10(7)/kg. The cumulative incidences (CI) of neutrophil and platelet engraftment were 84% and 72% at 60 and 180 days respectively; day 100 graft-versus-host disease (GVHD) (grade II to IV) was 43% and 3-year chronic GVHD was 32%. The CI of relapse, nonrelapse mortality, overall survival, and progression-free survival (PFS) at 3 years were 16%, 39%, 54%, and 45%, respectively. Fludarabine-sensitive disease at transplantation and use of low-dose TBI regimens were associated with acceptable PFS. In conclusion, use of RIC-UCBT seems to be feasible in patients with poor-risk CLL/SLL and improved outcomes were observed in patients with fludarabine-sensitive disease who received low-dose TBI regimens.