Donor choice according to age for allo-SCT for AML in complete remission

Donor selection in allogeneic stem cell transplantation

PURPOSE OF REVIEW

Recent progress in human leukocyte antigen (HLA) characterization, increased accrual of unrelated donors and cord blood units, and a new platform for haploidentical transplantation have resulted in the widespread availability of donors for allogeneic hematopoietic stem cell transplantation.

RECENT FINDINGS

Advances in HLA typing have identified an increasing number of loci and alleles that are crucial for successful transplantation. Newer HLA A, B, C, DRB1, and DQB1 alleles, DPB1 mismatches, and HLA B leader sequence matching are incorporated into donor selection algorithms. Donor selection is highly relevant because of recently published conflicting studies using different donor types. These studies are largely retrospective and compare patients with different diseases and stages, conditioning regimens, graft versus host disease (GVHD) prophylaxis, and time periods. A broad consensus indicates that the best donor is an available matched sibling, followed by a matched unrelated donor, and then alternative donors such as haploidentical, mismatched unrelated, and cord blood units. This consensus is being challenged by other factors, such as donor age, patient condition, urgency of transplantation, and costs involved.

SUMMARY

In this review, we will analyze the unique characteristics of each donor type, the HLA and non HLA factors that affect donor choices, and the outstanding comparative outcome studies of different donor usage in hematologic malignancies.

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.

Hematopoietic stem cell transplantation: an Italian monocentric experience on the health assessment and eligibility of adult-related donors

Introduction

Indications for HSCT are increasing worldwide, paralleled by a growing demand for donors of therapeutic cells.

Methods

Herein, we report our real-world experience of adult HPC donor assessment during a 5-year study period (2018-2023): we have retrospectively revised data of 455 potential related stem cell donors, consecutively evaluated at our center. Donor medical history was assessed by a questionnaire and an interview with a trained physician experienced in donation procedures to evaluate donor fitness and medical history. Pre-existing health disorders were fully investigated. Behavioral risk factors for communicable infectious diseases were also routinely explored.

Results and discussion

Overall, 351 donors were finally assessed as eligible for HPC donation, and 233 underwent stem cell collection, 158 through apheresis from mobilized peripheral blood, and 75 through bone marrow harvest. Among them, 27 donors were selected despite the presence of pre-existing health conditions, which would be potential exclusion criteria for unrelated donors: 16 suffered from well-controlled cardiovascular diseases (CVD) and 11 from allergic diathesis. Most of the selected donors with pre-existing disorders were candidates for apheresis HPC collection (21, 77.8%), while only six (22.2%) underwent BM harvest. We then analyzed the data relative to the corresponding 233 allogeneic HSCT to explore if the presence of pre-existing diseases in the donors could show any association with transplant characteristics. Transplants from CVD and allergy donors showed no significant disparities in comparison with those from healthy donors. A significant difference emerged regarding the disease severity, with a higher proportion of patients with high/very high disease risk index (DRI) among those receiving grafts from CVD donors (68.7% in transplants from CVD donors versus 36.0% in transplants from healthy donors, p=0.005). Multivariate analysis confirmed that high/very high DRI patients had an increased probability of receiving donations from CVD donors (OR, 4.89; 95%CI, 1.15-20.86; p=0.031). Among donors with well-controlled pre-existing conditions, no adverse events were recorded during stem cell collection or at follow-up. Our results suggest that in patients at high risk for relapse requiring a prompt allogeneic transplant, a familiar donor might be accepted for HPC apheresis donation on less strict criteria than unrelated donors, without risk for both donor and patient.

Effect of donor age in patients with acute myeloid leukemia undergoing haploidentical hematopoietic cell transplantation vary by conditioning intensity and recipient age

We investigated the impact of donor age (younger [≤35 years] vs. older [>35 years]) after accounting for other non-HLA and HLA factors on outcomes of patients with acute myeloid leukemia undergoing HLA-haploidentical hematopoietic cell transplantation (n = 790). The effect differed by conditioning-partly related to the differences in the recipient age in myeloablative (MAC; median 46 years) versus reduced-intensity/non-myeloablative conditioning (RIC/NMA; median 61 years) groups. With MAC (n = 320), donor age had no impact on acute graft-versus-host disease (GVHD), but older donors were associated with a significantly higher risk of chronic GVHD (hazard ratio [HR]: 1.6, 95% confidence interval [CI]: 1.10-2.30, p = .02) independent of recipient age and other factors. Donor age had no impact on either relapse or non-relapse mortality (NRM). The impact of donor/recipient age on overall survival changed over time. Older donors were associated with significantly higher late overall mortality (>6 months) in younger recipients (≤ 50 years; HR: 2.2, 95% CI: 1.03-4.6, p = .04) but not older recipients. With RIC/NMA (n = 470), neither recipient's nor donor's age influenced the risk of GVHD. Donor age had no significant impact on the risk of relapse, but older donors were associated with a significantly higher risk of NRM (HR: 1.6, 95% CI: 1.02-2.6, p = .04) independent of recipient age. Older donor age was associated with significantly higher late overall mortality (>9 months) in older recipients (>50 years; HR: 1.66, 95% CI: 1.0-2.67; p = .049) but not in younger recipients. Donor selection based on donor age may require a tailored approach for a particular recipient.

Favorable recovery profiles and good reliability among youngest unrelated stem cell donors supports lowering the minimum donor registration age

INTRODUCTION

Younger donor age in hematopoietic cell transplantation has been associated with improved overall and disease-free survival. Safety data on peripheral blood stem cell (PBSC) and bone marrow (BM) donation is well established, including in the <18-year old age group in the related setting. In response, Anthony Nolan became the first stem cell donor registry to lower the minimum age for unrelated donors to 16-years.

MATERIALS AND METHODS

This retrospective study reviewed unrelated donors donating PBSC or BM for the first time between April 2015 and October 2017 since adoption of the lowered recruitment age. Data were collected from registry electronic database and structured follow-up questionnaires. Primary outcomes were turnaround time from VT to donation, optimal cell yield achievement, and physical and emotional recovery.

RESULTS

Out of a total of 1013 donors, there were no differences between the different age groups in proportion of donors achieving optimal CD34+ or TNC (PBSC and BM, respectively). There was no increased central line requirement for younger donors or increased emergency telephone support. Youngest donors were more likely to report physical recovery 2 and 7 days post-PBSC (P = .024 and P = .015, respectively) as well as an earlier emotional recovery (P = .001) and fewer physical symptoms 1 week BM donation (P = .04).

CONCLUSION

This study shows that younger donors are as reliable as older donors, and have favorable recovery profiles without need for increased support at any stage of the donation, supporting Anthony Nolan recruitment strategy and offering reassurance to donor registries considering the same.

Impact of Donor Age in Haploidentical-Post-Transplantation Cyclophosphamide versus Matched Unrelated Donor Post-Transplantation Cyclophosphamide Hematopoietic Stem Cell Transplantation in Patients with Acute Myeloid Leukemia

Haploidentical hematopoietic cell transplantation (HCT) with post-transplantation cyclophosphamide (PTCy) graft-versus-host-disease (GVHD) prophylaxis is associated with inferior overall survival (OS) compared to HLA-matched unrelated donor (MUD) HCT with PTCy prophylaxis in patients receiving reduced-intensity conditioning (RIC). Given prognostic implications of donor age, we investigated the differences in outcomes of patients with acute myeloid leukemia (AML; n = 775) undergoing RIC-HCT with a younger MUD (age <35 years; n = 84) versus a younger haploidentical donor (age <35 years; n = 302) versus an older haploidentical donor (age ≥35 years; n = 389). The older MUD group was excluded from the analysis because of small numbers. The younger haploidentical donor group (median age, 59.5 years) was somewhat younger than the younger MUD group (median age, 66.8 years) and the older haploidentical donor group (median age, 64.7 years). More patients in the MUD group received peripheral blood grafts (82%) compared to the haploidentical donor groups (55% to 56%). In multivariate analysis, compared to the younger MUD group, the younger haploidentical donor group (hazard ratio [HR], 1.95; 95% confidence interval [CI], 1.22 to 3.12; P = .005) and the older haploidentical donor group (HR, 2.36; 95% CI, 1.50 to 3.71; P < .001) had a significantly inferior OS, and the younger haploidentical donor group (HR, 3.72; 95% CI, 1.39 to 9.93; P = .009) and older haploidentical donor group (HR, 6.91; 95% CI, 2.75 to 17.39; P < .001) had a significantly higher risk of nonrelapse mortality. The older haploidentical group had a significantly higher risk of grade II-IV acute GVHD (HR, 2.29; 95% CI, 1.38 to 3.80; P = .001) and grade III-IV acute GVHD (HR, 2.70; 95% CI, 1.09 to 6.71; P = .03). There were no significant differences across the groups in the incidence of chronic GVHD or relapse. Among adult AML patients in CR undergoing RIC-HCT with PTCy prophylaxis, a young MUD may be preferred over a young haploidentical donor.

Factors Associated with Opting Out of Donation among Registered Young Unrelated Hematopoietic Stem Cell Donors

Young adults enrolled in hematopoietic stem cell (HSC) donation registries, including the Be The Match registry in the United States, often opt out of the registry when a potential recipient is identified. This results in a limited supply from the most desirable allogeneic source of HSCs used in transplantation to treat serious health conditions. The differences in demographic, psychosocial, registry-related, and donation-related characteristics between those who continue to donation and those who opt out may elucidate the modifiable risk factors for attrition, but these characteristics have not been extensively studied in young donors up to age 30 years. Our goal was to study demographic, psychosocial, registry-related, and donation-related characteristics in a group of young HSC donor registry members who had recently been contacted about a potential recipient, to determine the key characteristics that differ between those who continued toward donation and those who opted out and to examine the extent of these differences. We conducted a cross-sectional survey in a random sample of young (age 18 to 30 years) current and former registry members, stratified by race/ethnicity and sex. Demographic, psychosocial (eg, life goals, HSC allocation mistrust), registry-related (eg context and motive for joining the registry), and donation-related (eg, ambivalence, religious objections to donation, knowledge about donation) characteristics were assessed. Chi-square and 2-sample t tests were used to examine differences between those who continued (CT-C group) and those who opted out (CT-NI group). Hierarchical logistic regression was used to estimate adjusted covariate effects on the odds of opting out. A total of 935 participants were surveyed. Donation-related knowledge was higher in the CT-C group than in the CT-NI group. HSC allocation mistrust, religious objections, and concerns about donation were higher in the CT-NI group. After adjusting for covariates in a logistic regression model, we found that having more intrinsic life goals, having more ambivalence, and talking with registry staff only once/twice were significantly associated with opting out of the registry. Ambivalence had the strongest association with opting out. In contrast, remembering joining the registry, believing that parents would support donation, and having medical concerns were significantly associated with continuing toward donation. This effect of medical concerns on donation was discovered only after adjusting for the related but distinct ambivalence variable, with the remaining effect of medical concerns relating to engagement with the donation process and information-seeking. The model had strong discriminative ability (area under the receiver operating characteristic curve = .92) and classification accuracy (86.6%). Our data indicate that among young adult members of a national HSC donor registry, ambivalence and limited contact with registry staff were more strongly associated with opting out of donation. Medical concerns were associated with continuing toward donation. Further studies are needed to confirm a causal link between medical concerns and continuing to donation among young donors. Our study suggests that these concerns might not be directly related to attrition, whereas other factors (eg, ambivalence, low donation-related knowledge) are associated with attrition and thus should be targeted for attrition reduction strategies.

Bispecific antibody-targeted T-cell therapy for acute myeloid leukemia

The management of relapsed or refractory acute myeloid leukemia (AML) continues to be therapeutically challenging. Non-toxic immunotherapy approaches are needed to provide long-term anti-leukemic effects. The goal of this study was to determine whether activated T cells (ATCs) armed with bispecific antibodies (BiAbs) could target and lyse leukemic and leukemic stem cells (LSCs). Anti-CD3 × anti-CD123 BiAb (CD123Bi) and anti-CD3 × anti-CD33GO (gemtuzumab ozogamicin [GO]) BiAb (CD33GOBi) were used to arm ATCs to produce bispecific antibody armed activated T cells (designated CD123 BATs or CD33GO BATs) to target AML cell lines, peripheral blood mononuclear cells from AML patients, and in vivo treatment of AML in xenogeneic NSG mice engrafted with leukemic cells. BATs exhibited high levels of specific cytotoxicity directed at AML cell lines at low 1:1 or 1:2 effector-to-target (E:T) ratios and secrete Th₁ cytokines upon target engagement. In vivo study in AML-engrafted NSG mice showed significantly prolonged survival in mice treated with CD33GO BATs (p < 0.0001) or CD123 BATs (p < 0.0089) compared to ATC-treated control mice. Patient samples containing leukemic blasts and LSCs when treated with CD33GO BATs or CD123 BATs for 18 h showed a significant reduction (50%-100%; p < 0.005) in blasts and 75%-100% reduction in LSCs (p < 0.005) in most cases compared to unarmed ATCs. This approach may provide a potent and non-toxic strategy to target AML blasts and LSCs and enhance chemo-responsiveness in older patients who are likely to develop recurrent diseases.

Impact of the combination of donor age and HLA disparity on the outcomes of unrelated bone marrow transplantation

Impact of donor age considering HLA disparity on hematopoietic cell transplantation (HCT) outcomes has not been fully evaluated. We evaluated 8486 patients who received unrelated bone marrow transplantation (UR-BMT) from 8/8 or 7/8 HLA-matched donors. Compared to 8/8 HLA-matched younger donors (<40 years), 8/8 HLA-matched older donors (subdistribution hazard ratio [SHR], 1.16; 95% CI, 0.97-1.38) and 7/8 HLA-matched younger donors (SHR, 1.33; 95% CI, 1.11-1.58) were associated with increased risk of grade III-IV acute graft-versus-host disease (aGVHD). 7/8 HLA-matched older donors had further increased risk (SHR, 2.00; 95% CI, 1.68-2.38) due to interaction between donor age and HLA disparity (p for interaction = 0.038). Progression-free survival (PFS) after UR-BMT with 8/8 HLA-matched younger donors was comparable to that after UR-BMT with 8/8 HLA-matched older donors, whereas UR-BMT with 7/8 HLA-matched younger or older donors was significantly associated with lower PFS than UR-BMT with 8/8 HLA-matched younger donors (younger donor; HR, 1.12; 95% CI, 1.04-1.21, older donor; HR, 1.28; 95% CI, 1.17-1.40; p for interaction = 0.079). In conclusion, adverse effect of increased donor age requires attention, especially in HLA-mismatched UR-BMT due to interaction between donor age and HLA disparity. Intensive aGVHD prophylaxis may be required to improve outcomes after HCT with mismatched older donors.

Hematopoietic Cell Transplantation in the Treatment of Newly Diagnosed Adult Acute Myeloid Leukemia: An Evidence-Based Review from the American Society of Transplantation and Cellular Therapy

The role of hematopoietic cell transplantation (HCT) in the management of newly diagnosed adult acute myeloid leukemia (AML) is reviewed and critically evaluated in this evidence-based review. An AML expert panel, consisting of both transplant and nontransplant experts, was invited to develop clinically relevant frequently asked questions covering disease- and HCT-related topics. A systematic literature review was conducted to generate core recommendations that were graded based on the quality and strength of underlying evidence based on the standardized criteria established by the American Society of Transplantation and Cellular Therapy Steering Committee for evidence-based reviews. Allogeneic HCT offers a survival benefit in patients with intermediate- and high-risk AML and is currently a part of standard clinical care. We recommend the preferential use of myeloablative conditioning in eligible patients. A haploidentical related donor marrow graft is preferred over a cord blood unit in the absence of a fully HLA-matched donor. The evolving role of allogeneic HCT in the context of measurable residual disease monitoring and recent therapeutic advances in AML with regards to maintenance therapy after HCT are also discussed.

Immunogenetics in stem cell donor registry work: The DKMS example (Part 2)

DKMS is a leading stem cell donor registry with more than 9 million donors. Donor registry activities share many touch points with topics from immunogenetics or population genetics. In this two-part review article, we deal with these aspects of donor registry work by using the example of DKMS. In the second part of the review, we focus on donor typing of non-HLA genes, the impact of donor age, gender and CMV serostatus on donation probabilities, the identification of novel HLA, KIR and MIC alleles by high-throughput donor typing, the activities of the Collaborative Biobank and pharmacogenetics in the donor registry context.

Impact of donor and recipient characteristics on graft-versus-host disease and survival in HLA-matched sibling hematopoietic stem cell transplantation

OBJECTIVE

To analyze the impact of donor- and recipient-related factors on Graft-versus-host disease (GVHD) and overall survival of transplantation from matched sibling donors.

METHOD

we retrospectively analyzed the clinical features of 68 consecutive hematological patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) from matched sibling from 2011 and 2017.

RESULTS

The incidence of Ⅱ- Ⅳacute GVHD (aGVHD) and chronic GVHD (cGVHD) after transplantation was 13.6 % and 19.7 %, respectively. We also noted the donor and recipient characteristics had no impact on Ⅱ- Ⅳ aGVHD incidence.We found sex mismatch (F-M) did not increase the risk of cGVHD in the model if a female donor was younger than 30 years (P = 1.000), but cGVHD increased if the female donor was ≥30 years (P = 0.002). Recipients≥40 years undergoing HCT from donors ≥30 years were at higher risk for cGVHD (P = 0.021). Development of Ⅱ- Ⅳ aGVHD and cGVHD had no effect on overall survival (P = 0.159, 0.081). Non-remission status at allo-HCT was linked to lower overall survival (P = 0.001).

CONCLUSION

The incidence of cGVHD was higher when male recipients received hematopoietic progenitor cells from female ≥30 years donors, and when older than 40 years recipients received hematopoietic progenitor cells from ≥30 years donors. Patients in non-remission status at allo-HCT was inclined to have lower overall survival.

The role of allogeneic stem cell transplantation in the management of acute myeloid leukaemia: a triumph of hope and experience

Acute myeloid leukaemia (AML) is the commonest indication for allogeneic stem cell transplantation (allo-SCT) worldwide. The accumulated experience of allografting in AML over the last four decades has provided critical insights into both the contribution of the conditioning regimen and the graft-versus-leukaemia effect to the curative potential of the most common form of immunotherapy utilised in standard clinical practice. Coupled with advances in donor availability and transplant technologies, this has resulted in allo-SCT becoming an important treatment modality for the majority of adults with high-risk AML. At the same time, advances in genomic classification, coupled with progress in the accurate quantification of measurable residual disease, have increased the precision with which allo-mandatory patients can be identified, whilst simultaneously permitting accurate identification of those patients who can be spared the toxicity of an allograft. Despite this progress, disease recurrence still remains a major cause of transplant failure and AML has served as a paradigm for the development of strategies to reduce the risk of relapse - notably the novel concept of post-transplant maintenance, utilising pharmacological or cellular therapies.

Outcomes of Related and Unrelated Donor Searches Among Patients with Primary Immunodeficiency Diseases Referred for Allogeneic Hematopoietic Cell Transplantation

Patients with primary immunodeficiencies (PIDs) are potentially cured by allogeneic hematopoietic cell transplantation (HCT). The spectrum of PIDs has expanded greatly beyond those that present in infancy or are diagnosed on newborn screening and require urgent, preemptive HCT. Many PID diagnoses are now made later in life, and the role of HCT is only considered for severe disease manifestations; in these cases, the kinetics and goals of a donor search may be different than for severe combined immunodeficiency. Across all PIDs, related donor searches have the additional selection factor of the inherited disease, and such searches may yield more limited options than searches for patients with hematologic malignancies; thus, unrelated donor options often become more critical in these patients. We retrospectively evaluated the outcomes of donor searches among patents with PIDs referred for HCT at the National Institutes of Health, where the minimum patient age for evaluation is 3 years and where donor options include matched sibling donors or matched related donors, HLA-haploidentical (haplo), or 7-8/8 HLA matched unrelated donors (mMUDs/MUDs). Patient (n = 161) and donor demographics, MUD search results, HLA typing, pedigrees, mutation testing, and donor selection data were collected. The National Marrow Donor Program HapLogic 8/8 HLA match algorithm was used to predict the likelihood of a successful MUD search and categorized as very good, good, fair, poor, very poor, or futile per the Memorial Sloan Kettering Cancer Center (MSKCC) Search Prognosis method. There were significant differences by PID mode of inheritance in patient age, disposition (receipt of HCT or not), donor source, and donor relatedness. A related or unrelated donor option could be identified for 94% of patients. Of living first-degree relatives (median, 3; range, 0 to 12 per patient), a median of 1 donor remained for autosomal dominant and X-linked (XL) diseases after HLA typing, mutation testing, and other exclusions, and a median of 2 donors remained for autosomal recessive (AR) diseases. Among patients with a PID of known mode of inheritance (n = 142), the best related donor was haplo for 99 (70%) patients, with 56 (39%) haplos age 40 years or older and 5 (4%) second-degree haplos; 13 (9%) had no family donor options. The best related donor was a heterozygote/asymptomatic carrier of the PID mutation in 36 (49%) patients with AR or XL disease (n = 73). Among patients with MUD search performed (n = 139), 53 (38%) had very poor/futile 8/8 MUD searches, including 6 (32%) of those with unknown PID mutation and therefore no family donor options. The MSKCC Search Prognosis was less favorable for those of non-European ancestry compared with European ancestry (P = .002). Most patients of Hispanic or African ancestry had very poor/futile MUD searches, 71% and 63%, respectively. No HCT recipients with very poor/futile MUD searches (n = 38) received 8/8 MUD grafts. Alternative donor options, including haplo and unrelated donors, are critical to enable HCT for patients with PIDs. MUD search success remains low for those of non-European ancestry, and this is of particular concern for patients with PIDs caused by an unknown genetic defect. Among patients with PIDs, related donor options are reduced and haplos age 40 years and older and/or mutation carriers are often the best family option.

Allogeneic Hematopoietic Cell Transplantation for Older Adults with Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a disease that affects adults aged 65 years and above, and survival in this population is poor. Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapy for these patients but is underutilized due to frequent comorbidities and perceived higher risk of treatment-related mortality and non-relapse mortality. Increasing data supports the utility of allo-HCT in fit older patients after intensive chemotherapy resulting in improvement of outcomes. With the development of reduced intensity and non-myeloablative conditioning regimens that are associated with lower rates of treatment-related toxicity and mortality, this has allowed more older patients with AML to receive allo-HCT. In this review, we provide some guidance on appropriate selection of older patients as transplant candidates, benefits and risks associated with allo-HCT, conditioning regimen choice, and stem cell transplant sources as they relate to the conduct of stem cell transplantation in older patients.

Donor characteristics and hematopoietic stem cell transplantation outcome: experience of a single center in Southern Brazil

Background

Hematopoietic stem cell transplantation is a curative treatment for many patients with hematological disorders. Donor-recipient genetic disparity, especially involving the human leukocyte antigen system is a critical factor for transplant outcome.

Objective

To evaluate retrospectively donor characteristics and correlations with the occurrence of acute and chronic graft-versus-host disease, disease-free survival and overall survival in a Brazilian population submitted to allogeneic hematopoietic stem cell transplantation between 1994 and 2012 in a single center.

Results

Three hundred and forty-seven consecutive transplantations were included. Related transplants (81.2%) were significantly more common than unrelated transplants (18.7%); donor and recipient median ages were 34 (range: 1-61) and 33 (range: 3-65) years respectively with donor HLAs being matched for 333 (95.9%) patients. Donor gender, cytomegalovirus status and ABO incompatibility did not influence the five-year overall survival. In univariate analyses, overall survival was negatively influenced by the presence of acute graft-versus-host disease (33% vs. 47%, respectively; p-value = 0.04), unrelated transplant (41.5% vs. 50.9%, respectively; p-value = 0.045) and donors aged over 40 years (41% vs. 52%, respectively; p-value = 0.03). Older donors were associated with a higher rate of acute (52% vs. 65.8%; p-value = 0.03) and chronic graft-versus-host disease (60% vs. 43%, respectively; p-value = 0.015). In multivariate analyses, acute graft-versus-host disease [relative risk (RR): 1.8; 95% confidence interval (CI): 1.1-29; p-value = 0.008] and older donors (RR: 1.6; 95% CI 1.11-2.24; p-value = 0.013) were associated with higher transplant-related mortality.

Conclusions

In transplant patients, to have a donor older than 40 years of age seems to significantly increase the incidence of acute and chronic graft-versus-host disease and transplant-related mortality with no impact on disease-free survival and overall survival. In spite of the rather small cohort of patients, these findings are similar to what is described in the literature suggesting that a younger donor should be chosen whenever possible.

Development of an Unrelated Donor Selection Score Predictive of Survival after HCT: Donor Age Matters Most

Donor factors, in addition to HLA matching status, have been associated with recipient survival in unrelated donor (URD) hematopoietic cell transplantation (HCT); however, there is no hierarchical algorithm that weights the characteristics of individual donors against each other in a quantitative manner to facilitate donor selection. The goal of this study was to develop and validate a donor selection score that prioritizes donor characteristics associated with better survival in 8/8 HLA-matched URDs. Two separate patient/donor cohorts, the first receiving HCT between 1999 and 2011 (n = 5952, c1), and the second between 2012 and 2014 (n = 4510, c2) were included in the analysis. Both cohorts were randomly spilt, 2:1, into training and testing sets. Despite studying over 10,000 URD transplants, we were unable to validate a donor selection score. The only donor characteristic associated with better survival was younger age, with 2-year survival being 3% better when a donor 10 years younger is selected. These results support previous studies suggesting prioritization of a younger 8/8 HLA-matched donor. This large dataset also shows that none of the other donor clinical factors tested were reproducibly associated with survival, and hence flexibility in selecting URDs based on other characteristics is justified. These data support a simplified URD selection process and have significant implications for URD registries.

Donor age determines outcome in acute leukemia patients over 40 undergoing haploidentical hematopoietic cell transplantation

Haploidentical hematopoietic cell transplantation (haplo-HCT) is being increasingly used in acute leukemia patients as an alternative transplant modality when matched sibling or matched unrelated donors are unavailable. As several potential haploidentical relative donors are typically available for a given patient, optimizing donor selection to improve clinical outcome is crucial. The impact of donor age and kinship on the outcome of acute leukemia patients is not clearly established in this setting. Using the multinational registry of the acute leukemia working party of the European society for blood and marrow transplantation we retrospective analyzed the clinical outcome of 1270 acute myeloid leukemia and acute lymphoblastic leukemia patients who underwent haplo-HCT between 2005 and 2015. Patients over the age of 40 were significantly affected by increasing donor age resulting in higher non-relapse mortality (NRM) [Hazard ratio (HR)=1.86, confidence interval (CI) 95%, 1.18-2.94; P = .007], inferior leukemia-free survival (LFS) (HR = 1.59, CI 95%, 1.13-2.24; P = .007), and overall survival (OS) (HR = 1.74, CI 95%, 1.22-2.47; P = .002) when donors were over the age of 40. Additionally, kinship was found to be prognostically significant as patients transplanted from children donors over the age of 35 experienced an increased rate of NRM (HR = 1.82, CI 95%, 1.13-2.9; P = .01), inferior LFS (HR = 1.5, CI 95%, 1.05-2.13; P = .03), and OS (HR = 1.5, CI 95%, 1.04-2.15; P = .03). For patients younger than 40 years, donor age and kinship were mostly not clinically impactful. Our data establish donor age and kinship as significant determinants of outcome following haplo-HCT for acute leukemia patients.

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.

Milestones of Hematopoietic Stem Cell Transplantation - From First Human Studies to Current Developments

Since the early beginnings, in the 1950s, hematopoietic stem cell transplantation (HSCT) has become an established curative treatment for an increasing number of patients with life-threatening hematological, oncological, hereditary, and immunological diseases. This has become possible due to worldwide efforts of preclinical and clinical research focusing on issues of transplant immunology, reduction of transplant-associated morbidity, and mortality and efficient malignant disease eradication. The latter has been accomplished by potent graft-versus-leukemia (GvL) effector cells contained in the stem cell graft. Exciting insights into the genetics of the human leukocyte antigen (HLA) system allowed improved donor selection, including HLA-identical related and unrelated donors. Besides bone marrow, other stem cell sources like granulocyte-colony stimulating-mobilized peripheral blood stem cells and cord blood stem cells have been established in clinical routine. Use of reduced-intensity or non-myeloablative conditioning regimens has been associated with a marked reduction of non-hematological toxicities and eventually, non-relapse mortality allowing older patients and individuals with comorbidities to undergo allogeneic HSCT and to benefit from GvL or antitumor effects. Whereas in the early years, malignant disease eradication by high-dose chemotherapy or radiotherapy was the ultimate goal; nowadays, allogeneic HSCT has been recognized as cellular immunotherapy relying prominently on immune mechanisms and to a lesser extent on non-specific direct cellular toxicity. This chapter will summarize the key milestones of HSCT and introduce current developments.

Survey of experts on therapeutic policies and proposals for the optimal timing for allogeneic peripheral blood stem cell transplantation in transfusion-dependent patients with myelodysplastic syndrome-refractory anemia

BACKGROUND

Most hypomethylating agent (HMA) responders with myelodysplastic syndrome (MDS) eventually need allogeneic stem cell transplantation (SCT) because they often acquire resistance to HMAs within two years of treatment. Considering the nature of MDS and the poor outcomes of SCT when performed after confirming the progression of MDS to acute myeloid leukemia (AML), allogeneic SCT should be performed with caution in patients with low-risk MDS.

METHODS

To address low-risk MDS, the Korean AML/MDS working party group designed a survey for 34 MDS experts in Korea on therapeutic HMA and allogeneic SCT policies for low-risk MDS. The level of consensus was defined as the percentage of agreement among the experts.

RESULTS

With regard to the optimal time for allogeneic SCT for HMA responders with MDS-RA, 76% experts agreed that allogeneic SCT should be performed when a patient has a low platelet count. With regard to the relapse pattern that was most commonly found during HMA treatment in responding patients with MDS-RA, 54% experts agreed that the most common pattern that indicated HMA failure was the gradual worsening of cytopenia.

CONCLUSION

The optimal time to perform allogeneic SCT in RA patients who achieved hematologic complete remission during HMA treatment is when the platelet count decreases. However, these suggestions need to be evaluated in larger future studies. Therefore, careful decisions should be taken at each step of allogeneic SCT to maximize the outcomes for patients with MDS-RA and iron overload.

In patients older than 55 years with AML in first CR, should we search for a matched unrelated donor when an old sibling donor is available?

Allogeneic hematopoietic transplantation is increasingly used in patients aged 55 years or more with AML. The question of whether outcomes can be improved with an allele-level 8/8 HLA-matched unrelated donor (MUD) rather than an older HLA-matched sibling (MSD, more than 55 years) is still unanswered. We thus analyzed outcomes in 714 patients aged 55 years and older with AML in first CR (CR1) who received PBSCs after a reduced-intensity conditioning hematopoietic cell transplant from a MUD (n=310) or a MSD (n=404) in a recent period (2005-2010). The 3-year cumulative incidences (CIs) of non-relapse mortality were 17% and 23% with MSD and MUD, respectively (P=0.17). The 3-year CIs of relapse were 37% and 30%, respectively (P=0.12), resulting in a 3-year CI of leukemia-free survival of 46% and 47%, respectively (P=0.51). The 3-year overall survival was 49% with both MSD and MUD. In conclusion, HLA-identical sibling donors aged 55 years or more should not be excluded because of age for patients aged 55 years and older with AML in CR1.

Comparable long-term outcome of unrelated cord blood transplantation with related bone marrow or peripheral blood stem cell transplantation in patients aged 45 years or older with hematologic malignancies after myeloablative conditioning

We investigated whether bone marrow or peripheral blood stem cells from older sibling donors or cord blood from unrelated donors provided a better outcome in allogeneic hematopoietic stem cell transplantation for relatively older patients who were candidates for myeloablative conditioning. Clinical outcomes of 97 patients aged 45 years or older with hematologic malignancies who received unrelated cord blood transplantation (CBT) (n = 66) or bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT) from related donors (n = 31) were compared. The cumulative incidences of grades III to IV acute and extensive chronic graft-versus-host diseases were similar between both groups. Although transplant-related mortality was significantly lower after CBT compared with BMT/PBSCT from related donors (hazard ratio [HR], .29, P = .04), overall mortality (HR, .72, P = .47) and relapse (HR, 2.02, P = .23) were not significantly different after CBT and BMT/PBSCT from related donors. These data suggest that CBT could be as safe and effective as BMT/PBSCT from older related donors for relatively older patients when it is used as a primary unrelated stem cell source.

Adoptable strategic approaches to improve outcomes of allogeneic peripheral blood stem cell transplantations from unrelated donors

While previous studies have shown comparable clinical results for related and unrelated bone marrow transplantation (BMT), the transplantation outcomes for related and unrelated peripheral blood stem cell transplantation (PBSCT) may not follow the same pattern due to a higher incidence of graft-versus-host disease (GVHD)-related morbidity and mortality in the case of long-term survival after unrelated PBSCT. Thus, given the higher possibility of an impaired quality of life due to severe GVHD in long-term survivors who receive unrelated PBSCT, the selection of the stem cell source needs to be decided very carefully. In addition, strategic approaches, such as the extended use of immunosuppressant as a GVHD prophylaxis, the use of antithymocyte globulins (ATGs), choosing a younger donor, and optimizing the CD34+ cell dose, need to be adopted to improve the transplantation outcomes by minimizing GVHD-related morbidity and mortality in an unrelated PBSCT setting. This review article provides a comparison of BMT and PBSCT, and related and unrelated PBSCT, plus introduces several adoptable strategies to improve the outcomes of unrelated PBSCT.

Pre-transplant prognostic factors of long-term survival after allogeneic peripheral blood stem cell transplantation with matched related/unrelated donors

Mobilized peripheral blood has become the predominant stem cell source for allogeneic hematopoietic cell transplantation. In this retrospective single center study of 442 patients with hematologic malignancies, we analyzed prognostic factors for long-term survival after peripheral blood stem cell transplantation from HLA-matched related or unrelated donors. To account for disease/status heterogeneity, patients were risk-stratified according to the Disease Risk Index. Five-year overall survival was similar after transplants with matched related and unrelated donors (45% and 46%, respectively; P=0.49). Because donor age ≥60 years impacted outcome during model building, we further considered 3 groups of donors: matched unrelated (aged <60 years by definition), matched related aged <60 years and matched related aged ≥60 years. In multivariate analysis, the donor type/age group and the graft CD34(+) and CD3(+) cell doses impacted long-term survival. Compared with matched unrelated donor transplant, transplant from matched related donor <60 years resulted in similar long-term survival (P=0.67) while transplant from matched related donor ≥60 years was associated with higher risks for late mortality (hazard ratio (HR) 4.41; P=0.006) and treatment failure (HR: 6.33; P=0.009). Lower mortality risks were observed after transplant with CD34(+) cell dose more than 4.5×10(6)/kg (HR: 0.56; P=0.002) and CD3(+) cell dose more than 3×10(8)/kg (HR: 0.61; P=0.01). The Disease Risk Index failed to predict survival. We built an "adapted Disease Risk Index" by modifying risks for myeloproliferative neoplasms and multiple myeloma that improved stratification ability for progression-free survival (P=0.04) but not for overall survival (P=0.82).