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

The rationale behind grafting haploidentical hematopoietic stem cells

The ability to perform hematopoietic cell transplant across major histocompatibility complex barriers can dramatically increase the availability of donors and allow more patients across the world to pursue curative transplant procedures for underlying hematologic disorders. Early attempts at haploidentical transplantation using broadly reactive T-cell depletion approaches were compromised by graft rejection, graft-versus-host disease and prolonged immune deficiency. The evolution of haploidentical transplantation focused on expanding transplanted hematopoietic progenitors as well as using less broadly reactive T-cell depletion. Significant outcome improvements were identified with technology advances allowing selective depletion of donor allospecific T cells, initially ex-vivo with evolution to its current in-vivo approach with the infusion of the highly immunosuppressive chemotherapy agent, cyclophosphamide after transplantation procedure. Current approaches are facile and portable, allowing expansion of allogeneic hematopoietic cell transplantation for patients across the world, including previously underserved populations.

Combined effect of unrelated donor age and HLA peptide-binding motif match status on HCT outcomes

ABSTRACT

An HLA-mismatched unrelated donor who is class I peptide-binding motif (PBM)-matched is preferred over a PBM-mismatched donor. We hypothesized that using a younger donor (aged ≤35 years vs >35 years) could compensate for the inferior overall survival (OS) associated with PBM mismatches. We compared 6 groups: HLA-matched/younger donor (n = 10 531), HLA-matched/older donor (n = 3572), PBM-matched/younger donor (n = 357), PBM-matched/older donor (n = 257), PBM-mismatched/younger donor (n = 616), and PBM-mismatched/older donor (n = 339) in patients undergoing transplantation with conventional graft-versus-host disease prophylaxis. In multivariate analysis, HLA-matched/younger donors were associated with superior OS relative to any other group. Pairwise comparisons showed that donor age significantly impacted OS in both HLA-matched and HLA-mismatched groups. Moreover, younger donors appeared to negate the detrimental effect of PBM mismatching: the PBM-matched/younger donor group had similar OS as the HLA-matched/older donor group and the PBM-mismatched/younger donor group had similar OS as the PBM-matched/older donor group. Our study suggests that older unrelated donor age and PBM mismatching confer similarly adverse effects on OS and the impacts are additive, a finding which may widen the "acceptable" donor pool. The best OS is observed with HLA-matched/younger donors and the worst with PBM-mismatched/older donors. These findings should be validated with other data sets and with posttransplantation cyclophosphamide-based prophylaxis.

Optimal Donor Selection Across Multiple Outcomes For Hematopoietic Stem Cell Transplantation By Bayesian Nonparametric Machine Learning

Allogeneic hematopoietic cell transplantation (HCT) is one of the only curative treatment options for patients suffering from life-threatening hematologic malignancies; yet, the possible adverse complications can be serious even fatal. Matching between donor and recipient for 4 of the HLA genes is widely accepted and supported by the literature. However, among 8/8 allele matched unrelated donors, there is less agreement among centers and transplant physicians about how to prioritize donor characteristics like additional HLA loci (DPB1 and DQB1), donor sex/parity, CMV status, and age to optimize transplant outcomes. This leads to varying donor selection practice from patient to patient or via center protocols. Furthermore, different donor characteristics may impact different post transplant outcomes beyond mortality, including disease relapse, graft failure/rejection, and chronic graft-versus-host disease (components of event-free survival, EFS). We develop a general methodology to identify optimal treatment decisions by considering the trade-offs on multiple outcomes modeled using Bayesian nonparametric machine learning. We apply the proposed approach to the problem of donor selection to optimize overall survival and event-free survival, using a large outcomes registry of HCT recipients and their actual and potential donors from the Center for International Blood and Marrow Transplant Research (CIBMTR). Our approach leads to a donor selection strategy that favors the youngest male donor, except when there is a female donor that is substantially younger.

Comparison of Older Related versus Younger Unrelated Donors for Older Recipients of Allogeneic Hematopoietic Cell Transplantation with Acute Myeloid Leukemia or Myelodysplastic Syndrome: A Large Single-Center Analysis

For patients undergoing allogeneic hematopoietic cell transplantation (alloHCT), HLA-matched related donors (MRDs) have traditionally been the preferred donor source. However, as the age of recipients increases, their sibling donors are aging as well. In this study, we investigated whether younger matched unrelated donors (MUDs) might be a better donor source than similarly aged sibling donors for patients age >60 years with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). A total of 499 patients age 60 to 70 years with AML or MDS who underwent alloHCT from an older MRD (donor age ≥50 years) or a younger MUD (donor age ≤35 years) between 2010 and 2022 were evaluated. Of these, 360 patients (72%) received an MUD graft and 139 (28%) received an MRD graft. The median recipient age was 64 years in the MRD group and 66 years in the MUD group. With a median follow-up among survivors of 53 months (range, 9 to 147 months ), the 4-year progression-free survival was 40% in the MRD group and 41% in the MUD group (P = .79) and the 4-year overall survival was 50% and 44%, respectively (P = .15), with no between-group differences in nonrelapse mortality, relapse, and acute or chronic graft-versus-host disease. In the MUD group, we also compared the effect of donor age 18 to 24 years and donor age 25 to 35 years and found no differences in outcomes between the groups. We conclude that outcomes are comparable between the use of older MRDs and use of younger MUDs for elderly patients with AML or MDS, that there is no donor age effect among younger MUDs, and that the use of either donor type is reasonable.

Age barriers in allogeneic hematopoietic cell transplantation: Raising the silver curtain

Allogeneic hematopoietic cell transplantation (HCT) is no longer exclusively for the young. With an aging population, development of non-intensive remission-inducing strategies for hematologic malignancies, and novel graft-versus-host disease-prevention platforms, an older population of patients is pursuing HCT. The evolving population of HCT recipients requires an overhaul in the way we risk-stratify and optimize patients prior to HCT. Here, we review the history and current state of HCT for older adults and propose an assessment and intervention flow to bridge the gaps in today's clinical guidelines.

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

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

Factors Associated with Opting Out of an Unrelated Hematopoietic Stem Cell Donor Registry: Differences and Similarities across Five Key Groups of Young Race/Ethnically Diverse Potential Donors in the United States

Young adults from underserved racial/ethnic groups are critically needed as unrelated hematopoietic stem cell (HSC) donors, yet they are more likely than other groups to opt out of donation after having matched a patient. Understanding which factors are most strongly associated with opting out among young underserved racial/ ethnic registered donors compared with their White counterparts will provide the basis for specific interventions to improve donor retention. We sought to determine the key, modifiable psychosocial, registry-related, and donation-related characteristics that are uniquely associated with opting out across 5 key racial/ethnic groups of young HSC donor registry members who had been contacted as a potential match for a patient. This study examines data from a large cross-sectional survey of young (age 18 to 30) registry members shortly after they preliminarily matched a patient (CT-stage) and continued toward or opted out of donation (CT-C and CT-NI), stratified by racial/ethnic group and sex. We assessed psychosocial, registry-related, and donation-related characteristics for all participants. We used chi-squared and F tests to assess differences between racial/ethnic groups. A separate logistic regression analysis for each racial/ethnic group was conducted to quantify adjusted associations between each variable and opting out. Then, we compared these associations across the racial/ethnic groups by evaluating the interaction effect between each variable and racial/ethnic group, with the same outcome (CT-C versus CT-NI) in question. Nine hundred thirty-five participants were surveyed, including 284 White, 165 Hispanic, 191 Black, 192 Asian/Pacific Islander, and 103 Multiracial/multiethnic participants. There were significant differences across racial/ethnic groups in values/goals, religious objections to donation, HSC-related medical mistrust, and parental involvement in donation decisions. Adjusted logistic regression subgroup analyses indicated that ambivalence was strongly associated with opting out across all racial/ethnic groups. Greater focus on intrinsic life goals (e.g., raising a family, becoming a community leader, influencing social values) was associated with opting out in the Multiracial/multiethnic, Hispanic, and Asian/Pacific Islander groups. Healthcare mistrust and insufficient registry contact was a significant factor for Hispanic participants. Protective factors against opting out included remembering joining the registry (Black participants), and parental support for donation decision (Asian/Pacific Islander participants). The performance of each logistic regression model was strong, with area-under-the curve ≥.88, CT-stage outcome classification accuracy ≥89%, and good fit between expected and observed opt-out probabilities. In the analysis across different racial/ethnic groups, the only significant interaction was race/ethnicity by whether more contact with the registry would have changed the decision at CT-stage; this variable was significant only for the Hispanic group. In the within-group analysis for Hispanic participants, the "more registry contact" variable was strongly associated with opting out (odds ratio 5.8, P = .03). Consistent with a growing body of HSC donor research, ambivalence was a key factor associated with opting-out for all racial/ethnic groups. Other key variables were differentially associated with opting-out depending on racial/ethnic group. Our study highlights key variables that registries should focus on as they develop targeted and tailored strategies to enhance commitment and reduce attrition of potential donors.

Epigenetic aging of human blood cells is influenced by the age of the host body

Allogenic hematopoietic stem cell transplantation is a therapeutic procedure performed over a wide range of donor and recipient age combinations, representing natural experiments of how the age of the recipient affects aging in transplanted donor cells in vivo. We measured DNA methylation and epigenetic aging in donors and recipients and found that biological epigenetic clocks are accelerated in cells transplanted into an older body and decelerated in a younger body. This is the first evidence that the age of the circulating environment influences human epigenetic aging in vivo.

Optimizing Access to Unrelated Donors in Canada: Re-Examining the Importance of Donor Factors on Outcomes Following Hematopoietic Cell Transplantation

HLA-matched allogeneic hematopoietic cell transplantation (HCT) is a curative therapy for many patients. Unrelated HLA-matched donors are the most frequently used donor for HCT. When more than one donor transplant option is available, transplant centers can select donors based on non-HLA factors. With improved ability to prevent and treat immune complications, such as graft-versus-host disease and infections, it may be possible to proceed more often using HLA-mismatched donors, allowing greater consideration of non-HLA factors, such as donor age, CMV serostatus, and ABO blood group matching, which have demonstrated important impacts on transplant outcomes. Additional factors to consider are donor availability rates and the usage of domestic donors to optimize outcomes. A review of non-HLA factors and considerations on the selection of optimal unrelated donors for HCT are provided within this updated current context.

A systematic review of lifespan studies in rodents using stem cell transplantations

Organismal aging involves the progressive decline in organ function and increased susceptibility to age-associated diseases. Regardless of its origin, cellular aging is consequently reflected at the level of organ and associated systems dysfunction. Aging of stem cell populations within the body and their decreased ability to self-renew, differentiate, and regenerate damaged tissues, is a key contributor to organismal decline. Based on this, supplementing young stem cells may delay tissue aging, improve frailty and extend health and lifespan. This review investigates studies in rodents using stem cell transplantation from either mice or human donors. The aim is to consolidate available information on the efficacy of stem cell therapies in rodent models and provide insights to guide further research efforts. Out of the 21 studies included in this review, the methodology varied significantly including the lifespan measurement. To enable comparison the median lifespan was calculated using WebPlotDigitizer 4.6 if not provided by the literature. A total of 18 out of 21 studies evidenced significant lifespan extension post stem cell transplant, with 7 studies demonstrating benefits in reduced frailty and other aging complications.

Donor-Derived Malignancy and Transplantation Morbidity: Risks of Patient and Donor Genetics in Allogeneic Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains a key treatment option for hematologic malignancies (HMs), although it carries significant risks. Up to 30% of patients relapse after allo-HSCT, of which up to 2% to 5% are donor-derived malignancies (DDMs). DDMs can arise from a germline genetic predisposition allele or clonal hematopoiesis (CH) in the donor. Increasingly, genetic testing reveals that patient and donor genetic factors contribute to the development of DDM and other allo-HSCT complications. Deleterious germline variants in CEBPA, DDX41, GATA2, and RUNX1 predispose to inferior allo-HSCT outcomes. DDM has been linked to donor-acquired somatic CH variants in DNMT3A, ASXL1, JAK2, and IDH2, often with additional new variants. We do not yet have evidence to standardize donor genetic sequencing prior to allo-HSCT. The presence of hereditary HM disorders should be considered in patients with myeloid malignancies and their related donors, and screening of unrelated donors should include family and personal history of cytopenia and HMs. Excellent multidisciplinary care is critical to ensure efficient timelines for screening and necessary discussions among medical oncologists, genetic counselors, recipients, and potential donors. After allo-HSCT, HM relapse monitoring with genetic testing effectively results in genetic sequencing of the donor, as the transplanted hematopoietic system is donor-derived, which presents ethical challenges for disclosure to patients and donors. We encourage consideration of the recent National Marrow Donor Program policy that allows donors to opt-in for notification about detection of their genetic variants after allo-HSCT, with appropriate genetic counseling when feasible. We look forward to prospective investigation of the impact of germline and acquired somatic genetic variants on hematopoietic stem cell mobilization/engraftment, graft-versus-host disease, and DDM to facilitate improved outcomes through knowledge of genetic risk.

Clonal hematopoiesis in the setting of hematopoietic cell transplantation

Clonal hematopoiesis (CH) in autologous transplant recipients and allogeneic transplant donors has genetic features and clinical associations that are distinct from each other and from non-cancer populations. CH in the setting of autologous transplant is enriched for mutations in DNA damage response pathway genes and is associated with adverse outcomes, including an increased risk of therapy-related myeloid neoplasm and inferior overall survival. Studies of CH in allogeneic transplant donors have yielded conflicting results but have generally shown evidence of potentiated alloimmunity in recipients, with some studies showing an association with favorable recipient outcomes.

Genetic Findings of Potential Donor Origin following Hematopoietic Cell Transplantation: Recommendations on Donor Disclosure and Genetic Testing from the World Marrow Donor Association

Following hematopoietic cell transplantation (HCT), recipients are subjected to extensive genetic testing to monitor the efficacy of the transplantation and identify relapsing malignant disease. This testing is increasingly including the use of large gene panels, which may lead to incidental identification of genetic and molecular information of potential donor origin. Deciphering whether variants are of donor origin, and if so, whether there are clinical implications for the donor can prove challenging. In response to queries from donor registries and transplant centers regarding best practices in managing donors when genetic mutations of potential donor origin are identified, the Medical Working Group of the World Marrow Donor Association established an expert group to review available evidence and develop a framework to aid decision making. These guidelines aim to provide recommendations on predonation consenting, postdonation testing of recipients, and informing and managing donors when findings of potential donor origin are identified in recipients post-transplantation. It is recognized that registries will have different access to resources and financing structures, and thus whenever possible, we have made suggestions on how recommendations can be adapted.

[Unrelated donor selection for allogeneic hematopoietic stem cell transplantation: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

The selection of a donor is an essential element in allogeneic hematopoietic stem cell transplantation. In the absence of an HLA-matched related donor, the selection of an unrelated donor is considered, and is currently the most common type of allogenic donor used in practice. Many criteria are considered for the selection when multiple donors are available, particularly in case of partial match. The aim of this workshop is to assist in the selection of an unrelated donor, in keeping with recent data from the literature.

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.

Choosing Between Older Matched Sibling Donor and Younger Matched Unrelated Donor in Allogeneic Hematopoietic Cell Transplantation: Comparison of Clinical Outcomes in Acute Myeloid Leukemia and Myelodysplastic Syndrome

The choice between an older matched sibling donor (MSD) and a younger matched unrelated donor (MUD) in allogeneic hematopoietic cell transplantation (HCT) remains a subject of ongoing debate. In this single-center retrospective study of 377 patients who received peripheral blood stem cell (PBSC) transplants for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS), we compared outcomes of 85 patients who received grafts from MSDs age >60 years and 292 patients who received grafts from MUDs age <30 years. Compared to recipients of MSD transplants, recipients of MUD transplants were younger and more likely to receive dual T cell depletion (TCD), a higher CD34+ cell dose, and a fresh graft. Recipients of MSD transplants were maintained on immunosuppressive therapy longer than those who received MUD grafts. We found no differences in overall survival, relapse-free survival, graft-versus-host disease (GVHD)-free and relapse-free survival, nonrelapse mortality, relapse, engraftment, graft failure, and acute GVHD between recipients of MSD grafts and recipients of MUD grafts. We report a higher 30-day incidence, but not 1-year incidence, of bloodstream infections among recipients of MUD transplants compared to subjects who received their grafts from a MSD. The incidence of moderate-severe chronic GVHD was higher in MSD graft recipients compared with MUD graft recipients in univariate analysis, but not in multivariate analysis. Although this difference could reflect the greater use of dual TCD, known to be associated with very low rates of chronic GVHD in MUD transplant recipients, the incidence of moderate-severe chronic GVHD was no different between MSD and MUD transplant recipients following propensity score matching, suggesting that other variables could be responsible. Taken together, our data suggest that in patients with AML or MDS who receive PBSC transplants, such factors as convenience, ease of access, and costs should be considered when selecting an older MSD over a younger MUD.

Existence of HLA-Mismatched Unrelated Donors Closes the Gap in Donor Availability Regardless of Recipient Ancestry

In patients without a matched sibling donor (MSD) or well-matched unrelated donor (MUD), hematopoietic cell transplantation (HCT) can still be successful when using an HLA-mismatched unrelated donor (MMUD) in combination with post-transplantation cyclophosphamide (PTCy), abatacept, or other novel approaches. This may allow clinicians to choose a suitable donor from a wide range of donor options while optimizing other donor selection characteristics, including donor age. We hypothesized that allowing for a 5/8 HLA match level considering high-resolution matching at HLA-A, -B, -C and -DRB1, there is a potential to close the donor availability gap for all patients regardless of their race/ethnicity. In this work, we estimate the likelihood of matching for all racial/ethnic groups at different HLA match thresholds. Our study aimed to assess the potential for identifying an available MUD or MMUD in the National Marrow Donor Program (NMDP)/Be The Match (BTM) donor registry for 21 detailed and 5 broad racial/ethnic groups, using high-resolution HLA matching for HLA-A, -B, -C, and -DRB1 at various levels (8/8, 7/8, 6/8, and 5/8). We used donor registry population data from the NMDP/BTM in 2020 and redistributed the donor registry data according to existing population ratios, accounting for demonstrated donor availability. Finally, we used a genetic model at the population level to estimate the match likelihood for detailed and broad racial/ethnic groups. Likelihood of 8/8 HLA match ranging from 16% to 74% were obtained for various detailed racial/ethnic groups with available donors age ≤35 years. When considering more mismatches in the HLA loci, registry coverage became >99% with a 5/8 HLA match level for donors of all ages or those age ≤35 years, with HLA-DPB1 T cell epitope permissive matching, or when searching for donors outside of their racial/ethnic group. Our registry models demonstrate the potential for using MMUDs at various HLA match levels to study whether this will expand access to HCT across racial/ethnic groups. Expanded donor options may erase the donor availability gap for all patients while allowing for selection of MMUDs with favorable characteristics, such as younger age.

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.

Younger Matched Unrelated Donors Confer Decreased Relapse Risk Compared to Older Sibling Donors in Older Patients with B Cell Acute Lymphoblastic Leukemia Undergoing Allogeneic Hematopoietic Cell Transplantation

Although allogeneic hematopoietic cell transplantation (alloHCT) offers cure for older patients with acute lymphoblastic leukemia (ALL), disease relapse remains a major issue. Whether matched sibling donors (MSDs) are still the preferred donor choice compared to younger matched unrelated donors (MUDs) in the contemporary era of improved transplantation practices remains unknown. This retrospective cohort registry study queried the Center for International Blood and Marrow Transplant Research (CIBMTR) database in patients with B cell ALL (B-ALL) age ≥ 50 years undergoing alloHCT from older MSDs (age ≥ 50 years) or younger MUDs (age ≤ 35 years) between 2011 and 2018. The study included common allograft types, conditioning regimens, and graft-versus-host disease (GVHD) prophylaxis strategies. The primary outcome was relapse risk, and secondary outcomes included nonrelapse mortality (NRM), GVHD, leukemia-free survival (LFS), and overall survival (OS). Among 925 eligible patients in the study cohort, 386 underwent alloHCT with an older MSD (median donor age, 58 years) and 539 underwent alloHCT from a younger MUD (median donor age, 25 year). In multivariable analysis, younger MUDs conferred a significantly decreased risk of relapse (hazard ratio [HR], .68; P = .002) compared with older MSDs. The adjusted cumulative incidence of relapse at 5 years was significantly lower with younger MUDs than with older MSDs (26% versus 37%; P = .001). Younger MUDs were associated with a greater risk of chronic GVHD compared to older MSDs (HR, 1.33; 95% confidence interval [CI], 1.10 to 1.61; P = .003). Compared to older MSDs, younger MUDs conferred an increased NRM (HR, 1.38; P = .02) and higher adjusted cumulative incidence of NRM at 5 years (31% versus 22%; P = .006). There were no differences in post-alloHCT OS or LFS rates between younger MUDs and older MSDs (OS: HR, 1.09; [P = .37]; LFS: HR, .95 [P = .57]). The use of younger MUDs could be considered as a possible way to prevent relapse after alloHCT in older adults with ALL. Combining the use of younger MUDs with improved strategies to reduce GVHD merits further exploration to improve outcomes.

Impact of Donor Age on Allogeneic Hematopoietic Cell Transplantation Outcomes in Older Adults with Acute Myeloid Leukemia

Allogeneic hematopoietic cell transplantation (alloHCT) provides cure for older patients with acute myeloid leukemia (AML); however, disease relapse remains a major concern. Based on recent data suggesting that younger donor age confers the greatest benefit for alloHCT with matched unrelated donors (MUDs), we attempted to answer a practical question: which donor type provides the best outcomes when an older patient with AML has a matched sibling donor (MSD, also older) versus the best MUD? This retrospective cohort registry study accessed data from the Center for International Blood and Marrow Transplant Research (CIBMTR) in patients with AML age ≥ 50 years undergoing alloHCT from older MSDs (age ≥ 50 years) or younger MUDs (age ≤ 35 years) between 2011 and 2018. The study included common allograft types, conditioning regimens, and graft-versus-host disease (GVHD) prophylaxis. The primary outcome was relapse risk. Secondary outcomes included nonrelapse mortality (NRM), GVHD, disease-free survival (DFS), and overall survival. Among 4684 eligible patients, 1736 underwent alloHCT with an older MSD (median donor age, 60 years), and 2948 underwent alloHCT from a younger MUD (median donor age, 25 years). In multivariable analysis, compared to older MSDs, the use of younger MUDs conferred a decreased relapse risk (hazard ratio [HR], .86; P = .005) and a significantly lower adjusted 5-year cumulative incidence of relapse (35% versus 41%; P = .003), but was associated with an increased risk for chronic GVHD (HR, 1.18; 95% confidence interval [CI], 1.08 to 1.29; P = .0002) and greater NRM only in the earlier period of 2011 to 2015 (HR, 1.24; P = .016). The corresponding NRM rates were significantly lower in the more recent period of 2016 to 2018 (HR, .78; P = .017). The adjusted 5-year DFS probability was 44% (95% CI, 42% to 46%) with an alloHCT from younger MUDs compared to 41% (95% CI, 38% to 43%) with older MSDs (P = .04). In summary, for older patients with AML undergoing alloHCT, the use of younger MUDs is associated with decreased relapse risk and improved DFS compared with the use of older MSDs.

Donor Selection for Allogeneic Hematopoietic Cell Transplantation

BACKGROUND

In Germany, each year over 3000 patients with malignant and non-malignant hematologic and systemic diseases are treated by allo - geneic hematopoietic cell transplantation (HCT). Genetic donor-recipient disparities, especially those concerning variable human leukocyte antigens (HLA), mediate both an immunotherapeutic effect and the risk of damage to healthy tissues ("graft-versus-host disease"). The adoption of evidencebased strategies for donor selection has been crucial for the continuous improvement of survival rates after allogeneic HCT, with over 50% of patients transplanted for standard indications-such as early-stage acute myeloid leukemia-alive at three years post-transplant.

METHODS

The PubMed database was selectively searched for literature on immunogenetic and clinical factors relevant to allogeneic HCT, as part of the process of establishing a German consensus statement on HCT donor selection.

RESULTS

The most important factor in donor selection is a match for the five major HLA loci (HLA-A, -B, -C, -DR, -DQ), either in genetically HLAidentical siblings or in unrelated but fully HLA-compatible donors from international registries. Additional selection criteria for the latter include com - patibility for the HLA-DP locus, donor age and sex, cytomegalovirus serostatus, and blood group. Related donors identical for only 50% of the HLA genes (haploidentical donors) as well as unrelated donors with a single HLA mismatch are both valid alternatives although they are associated with an up to 10% higher risk of mortality.

CONCLUSION

The refinement of donor selection strategies has been instrumental for the continuous improvement of patient survival rates after allogeneic HCT witnessed over the past decades. An interdisciplinary approach to donor selection based on up-to-date scientific evidence is crucial for optimizing patient outcomes.

Impact of Donor Age in Haploidentical-PTCy Versus MUD-PTCy HCT in AML patients

Haploidentical hematopoietic cell transplantation (HCT) with post-transplant 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 undergoing 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 (donor age <35 years, n=84) versus younger haploidentical (donor age <35 years, n=302) versus an older haploidentical (≥35 years, n=389) donor. The older MUD group was excluded due to small numbers. Patients in the younger haploidentical group (median age 59.5 years) were somewhat younger than the younger MUD (median 66.8 years) and the older haploidentical (median 64.7 years) groups. More patients in the MUD group received peripheral blood grafts (82%) compared to the haploidentical groups (55-56%). In multivariate analysis, as compared to the younger MUD group, the younger haploidentical [hazard ratio (HR) 1.95, 95% confidence interval (CI) 1.22-3.12, p=0.005)] and the older haploidentical (HR 2.36, 95% CI 1.50-3.71, p<0.001) groups had a significantly inferior OS, and the younger haploidentical (HR 3.72, 95% CI 1.39-9.93, p=0.009) and older haploidentical group (HR 6.91, 95% CI 2.75-17.39, p<0.001) had a significantly higher risk of NRM. The older haploidentical group had a significantly higher risk of grade II-IV acute GVHD (HR 2.29, 95% CI 1.38-3.80, p=0.001) and grade III-IV acute GVHD (HR 2.70, 95% CI 1.09-6.71, p=0.03). There were no significant differences in chronic GVHD or relapse between the groups. Among adult AML patients in CR undergoing RIC-HCT with PTCy prophylaxis, a young MUD may be preferred over a younger haploidentical donor.

Impact of Conditioning Regimen and Graft-versus-Host Disease Prophylaxis on The Outcome of Haploidentical Peripheral Blood Stem Cell Transplantation for High-Risk Severe Aplastic Anemia in Children and Young Adults: A Report from the Pediatric Severe Aplastic Anemia Consortium of India

Allogenic hematopoietic cell transplantation (HCT) is the best curative approach for patients with severe aplastic anemia (SAA). The outcomes of HCT from haploidentical family donors (HFDs) have improved, making it a feasible option for patients lacking an HLA-identical donor. However, data on HFD-HCT for younger patients with SAA is sparse. In this multicenter retrospective study, we evaluated the outcomes of 79 patients undergoing HFD-HCT for SAA. All the patients were heavily pretransfused, the median time to HCT was >12 months, and 67% had failed previous therapies. Conditioning was based on fludarabine (Flu)-cyclophosphamide (Cy)-antithymocyte globulin (ATG)/total body irradiation (TBI) with or without thiotepa/melphalan (TT/Mel). Post-transplantation Cy (PTCy) and calcineurin inhibitors (CNIs)/sirolimus were used as graft-versus-host disease (GVHD) prophylaxis with or without abatacept. The rate of primary graft failure (PGF) was 16.43% overall, lower in patients conditioned with TT/Mel. The incidences of acute and chronic GVHD were 26.4% and 18.9%, respectively. At a median follow-up of 48 months, the overall survival (OS) and event-free survival (EFS) were 61.6% and 58.1%, respectively. Both OS and EFS were better in the TT/Mel recipients and with abatacept as GVHD prophylaxis. On multivariate analysis, the use of abatacept was found to favorably impact the outcome variables, including GVHD and EFS. Our study suggests that PTCy-based HFD-HCT is a reasonable option for young patients with high-risk SAA, in whom optimization of conditioning and GVHD prophylaxis might further improve outcomes.

Determinants of refined GvHD-free, relapse-free survival after reduced-intensity allogeneic hematopoietic cell transplantation in older patients with myeloid malignancies

BACKGROUND

Older patients with AML/MDS have a poor prognosis with alloHCT as the only curative option. However alloHCT is challenging given its high TRM. Recently, a composite endpoint of GRFS was proposed to define transplant success. A single centre retrospective analysis was performed to determine the main variables influencing GRFS.

PATIENTS AND METHODSMETHODS

91 consecutive patients≥ 60 years (median 64 years, range 60-74) with AML/MDS who received reduced-intensity alloHCT during 2001-2017 analysed. Disease risk index (DRI) at HCT was low/intermediate in 47pts (52%) and high in 44 pts (48%).

RESULTS

After median follow-up for survivors of 56 months (range 7-144), 37 (40.6%) patients were alive. The OS, LFS and GRFS were 61.4%, 58.1%, 49.1% at 1 year and 35.5%, 32.3% and 23.1% at 5 years, respectively. The 1-year and 5-year incidences of NRM and relapse were 26.9%, 21.3% and 47.9% and 35.4%, respectively. In univariate analysis, high DRI was the strongest factor for worse OS (HR 2.121; p = 0.049), LFS (HR 1.924; p = 0.0123) and GRFS (HR 2.319; p = 0.0005). The donor age ≥ 62 years had a negative impact on OS (HR 2.110; p = 0.0345) and GRFS (HR 2.014; p = 0.0341). High DRI (HR 2.652; p = 0.0003) and donor age (HR 2.304; p = 0.0257) retained its significance in multivariate analysis for GRFS.

CONCLUSION

A significant portion of older patients with myeloid malignancies survive alloHCT without experiencing GRFS event with DRI as the main determinant of outcome. Negative impact of donor age≥ 62 years suggests preference of a young donor, regardless of being related or unrelated.

Short-Term Storage of Mobilized Peripheral Blood Stem Cells in a Closed System Changes the Microenvironment and May Affect the Quantity of CD34+ and CD34+CD38-CD45RA-CD90+ Cells

Hypoxic conditions preserve the multipotency and self-renewing capacity of murine bone marrow and human cord blood stem cells. Blood samples stored in sealed blood gas tubes become hypoxic as leukocytes metabolize and consume oxygen. Taken together, these observations suggest that peripheral blood stem cell (PBSC) samples stored under airtight conditions become hypoxic, and that the stem cells contained may undergo qualitative or quantitative changes. This study aimed to determine the effect of storage for 8 hours in a sealed system on PBSC samples. Granulocyte colony-stimulating factor-mobilized PBSC samples were collected prospectively from 9 patients with myeloma or amyloidosis prior to apheresis, followed by measurement of CO2, O2, hydrogen ion (pH), lactate, and glucose concentrations in the blood and immunophenotyping of stem cell and multipotent progenitor cell populations before and after 8 hours of storage in sealed blood collection tubes. Blood concentrations of O2 and glucose and pH measurements were significantly decreased, whereas concentrations of CO2 and lactate were significantly increased after storage. Significantly higher concentrations of CD34+ cells (552 ± 84 cells/106 total nucleated cells [TNCs] versus 985 ± 143 cells/106 TNCs; P = .03), CD34+CD38- cells (98 ± 32 cells/106 TNCs versus 158 ± 52 cells/106 TNCs; P = .03), CD34+CD38+ cells (444 ± 92 cells/106 TNCs versus 789 ± 153 cells/106 TNCs; P = .03), and CD34+CD38-CD45RA-CD90+ cells (55 ± 17 cells/106 TNCs versus 89 ± 25 cells/106 TNCs; P = .02) were detected after 8 hours of storage. The changes in concentrations of CD34+CD38+ cells and CD34+ cells were inversely associated with the change in glucose concentration (P = .003 and P < .001, respectively) and positively associated with the change in lactate concentration (P = .01 and P <.001, respectively) after 8 hours of airtight storage. Storage of PBSC samples in a sealed, airtight environment is associated with microenvironmental changes consistent with hypoxia and increased concentrations of immunophenotypically defined stem cells. These results may have clinical implications with regard to the collection and processing of stem cell products and warrant confirmation with functional and mechanistic studies.

Human Leucocyte Antigen System and Selection of Unrelated Hematopoietic Stem Cell Donors: Impact of Patient-Donor (Mis)matching and New Challenges with the Current Technologies

The selection of hematopoietic stem cell donors for allogeneic transplantation (allo-HSCT) is mainly driven by human leucocyte antigen (HLA) matching between patient and donor, with HLA-identical matched siblings being the preferred choice in most situations. Although other clinical and demographical variables matter, especially, donor age, which is unequivocally associated with better transplant outcomes, the histocompatibility criteria have a central role in the search for the best donor, particularly in the setting of unrelated allo-HSCT where HLA disparities between patient and donor are frequent. The present review is focused on the role of HLA incompatibilities on patient outcome according to the most recent literature, in an attempt to guide transplant physicians and search coordinators during the process of adult unrelated-donor selection. The technological progresses in HLA typing, i.e., with next-generation sequencing (NGS), now allow disclosing a growing number of HLA incompatibilities associated with a heterogeneous and sometimes unknown spectrum of clinical severity. Their immunogenic characteristics, i.e., their position inside or outside the antigen recognition domain (ARD), their permissiveness, their intronic or exonic nature and even the expected expression of the HLA loci where those mismatches occur, will be presented and discussed here, integrating the advances in the immunobiology of transplantation with survival and toxicity outcomes reported in the most relevant studies, within the perspective of improving donor selection in the current practice.

Hematology 2022-what is complete HLA match in 2022?

Allogeneic hematopoietic cell transplantation (alloHCT) often represents the only curative treatment for various malignant and nonmalignant disorders. Initially, the only suitable donors were considered human leukocyte antigen (HLA)-matched or partially matched relatives. The founding of international unrelated donor and umbilical cord blood registries expanded unrelated donor options and access for patients. In the absence of a matched sibling donor (MSD) with 13% to 51% availability, the current consensus recommends use of a matched unrelated donor (MUD) at HLA-A, B, C, and DRB1 with consideration of matching at HLA-DPB1 and -DQB1. MUD donor availability (donor willing and available to donate) ranges from 29% to 78% with African American patients on the lower end and white non-Hispanic patients with the highest likelihood of a match. Recent studies comparing donor to no-donor treatment options in malignant disease consistently point to substantially better outcomes following alloHCT. In the absence of an MSD or MUD, alternative donor choices turn to haploidentical related (Haplo), mismatched unrelated donor (MMUD), and umbilical cord blood (UCB). Novel strategies for alloHCT, including the use of posttransplant cyclophosphamide-based graft vs host disease prophylaxis, have expanded the safety and effectiveness of transplant procedures across HLA barriers using Haplo and MMUD. The less restrictive matching requirements for UCB transplant are well documented and allow for transplant across multiply mismatched HLA alleles. When all donor options are considered, nearly all patients have an available donor. Here we discuss the likelihood of donor availability, complete HLA match by available donor type, and current controversies warranting future research.

Decoupling blood telomere length from age in recipients of allogeneic hematopoietic cell transplant in the BMT-CTN 1202

The age of allogeneic hematopoietic cell transplant (HCT) donors and their hematopoietic cell telomere length (TL) might affect recipients’ outcomes. Our goals were to examine the possible effect of these donors’ factors on the recipients’ hematopoietic cell TL and quantify hematopoietic cell TL shortening in the critical first three-month post-HCT. We measured hematopoietic cell TL parameters in 75 recipient-donor pairs, from the Blood and Marrow Transplant Clinical Trials Network (protocol#1202), by Southern blotting (SB), the Telomeres Shortest Length Assay (TeSLA), and quantitative PCR (qPCR). Recipients’ hematopoietic cell TL parameters post-HCT correlated with donors’ age (p<0.001 for all methods), but not recipients’ own age, and with donors’ pre-HCT hematopoietic cell TL (p<0.0001 for all). Multivariate analyses showed that donors’ hematopoietic cell TL pre-HCT, independent of donors’ age, explained most of the variability in recipients’ hematopoietic cell TL post-HCT (81% for SB, 56% for TeSLA, and 65% for qPCR; p>0.0001 for all). SB and TeSLA detected hematopoietic cell TL shortening in all recipients post-HCT (mean=0.52kb and 0.47kb, respectively; >15-fold the annual TL shortening in adults; p<0.00001 for both), but qPCR detected shortening only in 57.5% of recipients. TeSLA detected a buildup of post-HCT of telomeres <3 kb in 96% of recipients (p<0.0001). In conclusion, HCT decouples hematopoietic cell TL in the recipients from their own age to reflect the donors’ age. The potential donors’ age effect on outcomes of HCT might be partially mediated by short hematopoietic cell TL in older donors. qPCR-based TL measurement is suboptimal for detecting telomere shortening post-HCT.

Why We Swab: A library of stories in stem cell donation

BACKGROUND

Stories are powerful in their ability to disseminate information in a meaningful way. We hypothesized that a stem cell donation story library optimized for social media could support the education and recruitment of committed unrelated hematopoietic stem cell donors from needed demographic groups.

STUDY DESIGN AND METHODS

We developed Why We Swab, a library of stories on stem cell donation (facebook.com/WhyWeSwab; instagram.com/WhyWeSwab; twitter.com/WhyWeSwab), and evaluated its impact across social and traditional media as well as on eligible potential donors' knowledge and attitudes towards donation.

RESULTS

As of December 2021, the library included 28 story arcs featuring 45 storytellers from diverse ancestral backgrounds, including 8 donor-recipient stories. Overall, the stories reached >92,000 people across social media. Notably, stories were republished by 18 print/ broadcast media outlets in Canada and by major medical organizations. A series of stories shown to 33 eligible potential donors improved mean total scores on a donation knowledge test (64% to 85%, p < 0.001), reduced mean ambivalence scale scores (3.85 to 2.70, p < 0.001), and improved participants' willingness to register as donors (45% to 73%, p < 0.005). Data are also shown demonstrating that stakeholders valued the library and that its deployment was associated with improved donor recruitment outcomes in Canada.

CONCLUSION

Why We Swab is accessible and relevant to a wide audience, including stem cell donor registries and recruitment organizations seeking to improve their recruitment efforts as well as to blood and organ & tissue donation organizations who can adapt the Why We Swab model to their audiences.

Current donor selection strategies for allogeneic hematopoietic cell transplantation

Since the first allogeneic hematopoietic stem cell transplantation (HCT) was performed by Dr. E. Donnall Thomas in 1957, the field has advanced with new stem cell sources, immune suppressive regimens, and transplant protocols. Stem cells may be collected from bone marrow, peripheral or cord blood from an identical twin, a sibling, or a related or unrelated donor, which can be human leukocyte antigen (HLA) matched, mismatched, or haploidentical. Although HLA matching is one of the most important criteria for successful allogeneic HCT (allo-HCT) to minimize graft vs host disease (GVHD), prevent relapse, and improve overall survival, the novel immunosuppressive protocols for GVHD prophylaxis offered improved outcomes in haploidentical HCT (haplo-HCT), expanding donor availability for the majority of HCT candidates. These immunosuppressive protocols are currently being tested with the HLA-matched and mismatched donors to improve HCT outcomes further. In addition, fine-tuning the DPB1 mismatching and discovering the B leader genotype and mismatching may offer further optimization of donor selection and transplant outcomes. While the decision about a donor type largely depends on the patient's characteristics, disease status, and the transplant protocols utilized by an individual transplant center, there are general approaches to donor selection dictated by donor-recipient histocompatibility and the urgency for HCT. This review highlights recent advances in understanding critical factors in donor selection strategies for allo-HCT. It uses clinical vignettes to demonstrate the importance of making timely decisions for HCT candidates.

Donor Age and Non-Relapse Mortality: Study of Their Association after HLA-Matched Allogeneic Hematopoietic Cell Transplantation for Acute Myeloid Leukemia and Myelodysplastic Syndrome

The purpose of this retrospective study was to study the correlation between donor age (DA) and non-relapse mortality (NRM) and relapse incidence (RI) among patients treated with allogeneic hematopoietic cell transplantation (aHCT) for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) in a single Canadian center. Data from 125 consecutive patients transplanted with a matched related or unrelated donor between 2015 and 2020 were analyzed using multivariable models. After a median follow-up of 2.8 years, the cumulative incidences of NRM and relapse were 19% and 35% at 5 years. Despite being independently associated with NRM and relapse-free survival (RFS), DA was not associated with RI. The independent determinants of NRM in addition to DA were patient age and hematopoietic cell transplantation comorbidity index (HCT-CI), independently of donor kinship. The effect of DA on NRM was found to be significantly increased over the age of 50 years. DA was not associated with incidence of acute graft-versus-host disease (aGVHD) but showed an association with the occurrence of chronic GVHD (cGVHD). In conclusion, younger donors should be favored to limit NRM and increase RFS in HLA-matched aHCT. The etiological mechanisms behind the association of DA with higher NRM remain to be elucidated.

The Hunt Is On! In Pursuit of the Ideal Stem Cell Population for Cartilage Regeneration

Cartilage injury and degeneration are hallmarks of osteoarthritis (OA), the most common joint disease. OA is a major contributor to pain, loss of function, and reduced quality of life. Over the last decade, considerable research efforts have focused on cell-based therapies, including several stem cell-derived approaches to reverse the cartilage alterations associated with OA. Although several tissue sources for deriving cell-based therapies have been identified, none of the resident stem cell populations have adequately fulfilled the promise of curing OA. Indeed, many cell products do not contain true stem cells. As well, issues with aggressive marketing efforts, combined with a lack of evidence regarding efficacy, lead the several national regulatory bodies to discontinue the use of stem cell therapy for OA until more robust evidence becomes available. A review of the evidence is timely to address the status of cell-based cartilage regeneration. The promise of stem cell therapy is not new and has been used successfully to treat non-arthritic diseases, such as hematopoietic and muscle disorders. These fields of regenerative therapy have the advantage of a considerable foundation of knowledge in the area of stem cell repair mechanisms, the role of the stem cell niche, and niche-supporting cells. This foundation is lacking in the field of cartilage repair. So, where should we look for the ideal stem cell to regenerate cartilage? It has recently been discovered that cartilage itself may contain a population of SC-like progenitors. Other potential tissues include stem cell-rich dental pulp and the adolescent growth plate, the latter of which contains chondrocyte progenitors essential for producing the cartilage scaffold needed for bone growth. In this article, we review the progress on stem cell therapies for arthritic disorders, focusing on the various stem cell populations previously used for cartilage regeneration, successful cases of stem cell therapies in muscle and hemopoietic disorders, some of the reasons why these other fields have been successful (i.e., “lessons learned” to be applied to OA stem cell therapy), and finally, novel potential sources of stem cells for regenerating damaged cartilage in vivo.

HLA-Matching with PTCy: A Reanalysis of a CIBMTR Dataset with Propensity Score Matching and Donor Age

A reanalysis including donor age and using propensity score matching shows no major differences in survival or relapse.

Data sharing and collaborative reanalysis enhance our recognition of the nuances of complex statistical methodologies and published results.

Blood or marrow transplantation (BMT) outcomes using haploidentical donors (Haplo) and posttransplant cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis compare favorably to HLA-matched donors using calcineurin inhibitor–based prophylaxis. A recent Center for International Blood and Marrow Transplant Research analysis of patients receiving homogenous PTCy-based prophylaxis found that, with reduced intensity conditioning, Haplo BMTs had worse outcomes than matched unrelated donor (MUD) BMTs. Due to significant differences between groups, we reanalyzed the dataset using propensity score matching and, additionally, added a donor age variable. After matching MUD BMTs to Haplo BMTs in a 1:5 ratio, no significant differences were found between groups across all measured baseline characteristics. Outcomes analyses demonstrated no significant differences in overall survival (hazard ratio [HR] of mortality with MUD vs Haplo [95% confidence interval], 0.95 [0.65-1.16], P = .75), disease-free survival (HR of relapse or death, 0.98 [0.73-1.18], P = .89), relapse rate (HR, 1.06 [0.77-1.38], P = .69), or nonrelapse mortality (NRM) (HR, 0.85 [0.42-1.13], P = .49) between groups. After stratification by conditioning intensity, MUD BMTs in the reduced-intensity cohort had lower risk of NRM (HR, 0.56 [0.14-0.99], P = .05), with no significant difference in other clinical outcomes. These results suggest the effect of HLA matching on BMT outcomes with PTCy is less meaningful than previously reported. Timely identification of a young, at least half-matched (related or unrelated) donor may be more important than finding a fully matched donor if the latter leads to a delay in BMT or use of an older donor.

Haploidentical vs Matched Unrelated vs Matched Sibling Donor HCT with Post-Transplantation Cyclophosphamide

With the use of post-transplantation cyclophosphamide (PTCy), the outcomes of mismatched related donor hematopoietic cell transplantation (HCT) are now approaching those of matched donor HCT. Here we compared haploidentical donor HCT versus HLA-matched unrelated donor (MUD) HCT and HLA-identical sibling donor (MSD) HCT in a cohort in which all patients received PTCy for graft-versus-host disease (GVHD) prophylaxis. We included 661 patients (275 haploidentical, 246 MUD, and 140 MSD HCT). The most common diagnoses were acute myelogenous leukemia and myelodysplastic syndrome. In multivariate analysis, the haploidentical group was found to have significantly higher nonrelapse mortality (NRM) (hazard ratio [HR], 3.2; 95% confidence interval [CI], 2 to 4.9; P < .001) and inferior progression-free survival (HR, 1.8; 95% CI, 1.4 to 2.4; P < .001) and overall survival (OS; HR, 2.2; 95% CI, 1.6 to 3; P < .001) compared with the MUD group. Relapse was the most common cause of death in all groups. Among causes of NRM, the haploidentical group had more infection-related deaths and fewer GVHD-related deaths than the other groups. The haploidentical group also had a higher risk of viral and fungal infections, grade ≥3 hemorrhagic cystitis, and cardiovascular toxicities and slower reconstitution of CD4, CD8, and regulatory T cells but faster reconstitution of natural killer cells. In an exploratory analysis, older patients with older donors (>50 years for both) appeared to have particularly high NRM and lower OS in the haploidentical group compared with the other groups. Our data suggest that even with the use of PTCy, the outcomes of haploidentical HCT are inferior to those of HLA-matched donor HCT.

Relapse and Disease-Free Survival in Patients With Myelodysplastic Syndrome Undergoing Allogeneic Hematopoietic Cell Transplantation Using Older Matched Sibling Donors vs Younger Matched Unrelated Donors

IMPORTANCE

Matched sibling donors (MSDs) are preferred for allogeneic hematopoietic cell transplantation (allo-HCT) in myelodysplastic syndrome even if they are older. However, whether older MSDs or younger human leukocyte antigen-matched unrelated donors (MUDs) are associated with better outcomes remains unclear.

OBJECTIVE

To investigate whether allo-HCT for myelodysplastic syndrome using younger MUDs would be associated with improved disease-free survival and less relapse compared with older MSDs.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study assessed data reported to the Center for International Blood and Marrow Transplant Research database from 1761 adults 50 years or older with myelodysplastic syndrome who underwent allo-HCT using an older MSD or younger MUD between January 1, 2011, and December 31, 2017, with a median follow-up of 48 months. Data analysis was performed from January 8, 2019, to December 30, 2020.

INTERVENTIONS/EXPOSURES

Allo-HCT from an older MSD (donor age ≥50 years) or a younger MUD (donor age ≤35 years).

MAIN OUTCOMES AND MEASURES

The primary outcome was disease-free survival. Secondary outcomes were overall survival, relapse, nonrelapse mortality, acute graft-vs-host disease (GVHD), chronic GVHD, and GVHD-free relapse-free survival.

RESULTS

Of 1761 patients (1162 [66%] male; median [range] age, 64.9 [50.2-77.6] years in the MSD cohort and 66.5 [50.4-80.9] years in MUD cohort), 646 underwent allo-HCT with an older MSD and 1115 with a younger MUD. In multivariable analysis, the rate of disease-free survival was significantly lower in allo-HCTs with older MSDs compared with younger MUDs (hazard ratio [HR], 1.17; 95% CI, 1.02-1.34; P = .02), whereas the difference in overall survival rate of allo-HCT with younger MUDs vs older MSDs was not statistically significant (HR, 1.13; 95% CI, 0.98-1.29; P = .07). Allo-HCT with older MSDs was associated with significantly higher relapse (HR, 1.62; 95% CI, 1.32-1.97; P < .001), lower nonrelapse mortality (HR, 0.76; 95% CI, 0.59-0.96; P = .02), lower acute GVHD (HR, 0.52; 95% CI, 0.42-0.65; P < .001), chronic GVHD (HR, 0.77; 95% CI, 0.64-0.92; P = .005), and a lower rate of GVHD-free relapse-free survival beyond 12 months after allo-HCT (HR, 1.42; 95% CI, 1.02-1.98; P = .04).

CONCLUSIONS AND RELEVANCE

This cohort study found higher disease-free survival and lower relapse for allo-HCT in myelodysplastic syndrome using younger MUDs compared with older MSDs. The risk of nonrelapse mortality and GVHD was lower with older MSDs. These results suggest that the use of younger MUDs should be considered in the donor selection algorithm for myelodysplastic syndrome, in which it is pivotal to minimize relapse given limited treatment options for managing relapsed disease.

Development and evaluation of checklists to support the recruitment of committed hematopoietic stem cell donors

BACKGROUND

Checklists are memory recall tools used across healthcare to improve outcomes. Here, we describe the development and evaluation of checklists to support recruitment of committed allogeneic hematopoietic stem cell donors.

STUDY DESIGN AND METHODS

Checklists were developed with the following objectives: (1) improve best-practice adherence; (2) reduce errors; and (3) support standardization at stem cell drives. Topics included: recruiting needed donors; securing informed consent; maintaining good-documentation practices; and supervising registration and tissue sample collection. Checklists were iteratively revised with input from stakeholders. We evaluated the checklists by examining recruitment outcomes and errors (i.e., preventing registrants from being listed as donors) pre- (11/2011-8/2016) and post- (9/2016-11/2019) implementation by the Canadian donor recruitment organization Stem Cell Club. Quantitative and qualitative methods were employed to analyze recruiters' perspectives on the checklists.

RESULTS

The checklists supported recruitment of donors from needed demographic groups as Stem Cell Club expanded its recruitment effort from 4118 registrants (60% male, 58% non-European) pre-implementation to 10,621 (52% male, 56% non-European) post-implementation. Checklist implementation was associated with a marked reduction in errors (from 13.2% to 1.9%) and a three-fold increase in the match rate of recruited donors (from 0.024% to 0.075%). Qualitative and quantitative analysis of recruiter feedback supported that the checklists' objectives were realized from the recruiter perspective.

DISCUSSION

We developed checklists to support donor recruitment and showed that their implementation was valued by recruiters and associated with both reduced errors and improved donor recruitment outcomes. The checklists are relevant to donor recruitment organizations worldwide.

A novel Iowa-Mayo validated composite risk assessment tool for allogeneic stem cell transplantation survival outcome prediction

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative option for many hematologic conditions and is associated with considerable morbidity and mortality. Therefore, prognostic tools are essential to navigate the complex patient, disease, donor, and transplant characteristics that differentially influence outcomes. We developed a novel, comprehensive composite prognostic tool. Using a lasso-penalized Cox regression model (n = 273), performance status, HCT-CI, refined disease-risk index (rDRI), donor and recipient CMV status, and donor age were identified as predictors of disease-free survival (DFS). The results for overall survival (OS) were similar except for recipient CMV status not being included in the model. Models were validated in an external dataset (n = 378) and resulted in a c-statistic of 0.61 and 0.62 for DFS and OS, respectively. Importantly, this tool incorporates donor age as a variable, which has an important role in HSCT outcomes. This needs to be further studied in prospective models. An easy-to-use and a web-based nomogram can be accessed here: https://allohsctsurvivalcalc.iowa.uiowa.edu/ .

Development and evaluation of a community of practice to improve stem cell donor recruitment in Canada

Background and Objectives Communities of practice (CoPs) represent effective models to achieve quality outcomes in health care. We report the development and evaluation of a CoP to improve stem cell donor recruitment in Canada. Materials and Methods In September 2017, we invited national stakeholders in stem cell donor recruitment to participate in a Facebook group and regular e-meetings. E-meetings involved speakers and roundtable discussion on topics related to donor recruitment. The Facebook group facilitated sharing of resources. We evaluated stakeholder perspective of the CoP and the impact on recruitment outcomes. Results As of December 2020, the CoP included 382 members who published 243 posts to the Facebook group about patient/donor stories (40%), resources (27%), updates/questions (21%) and recruitment outcomes (12%). In January 2020, we surveyed 44 CoP participants; the majority felt that the Facebook group (86%) and e-meetings (59%) supported the community, and that the CoP fostered collaboration (82%), improved their donor recruitment knowledge (75%) and practice (77%) and improved their ability to recruit needed donors (64%). The launch of the CoP correlated with improved donor recruitment outcomes. In 2016-2017, CoP participants recruited 2918 registrants (46% male; 55.9% non-Caucasian) compared to 4531 registrants in 2018-2019 (52.9% male; 62.7% non-Caucasian). Members of the CoP developed innovative resources to support recruitment efforts and led national campaigns securing coverage in major media outlets. Conclusion We describe the first CoP in stem cell donor recruitment to be formally evaluated. The CoP model may be adopted by donor recruitment organisations, registries and blood banks worldwide to improve recruitment outcomes. HIGHLIGHTS: • A community of practice (CoP) in stem cell donor recruitment was valued by participants and supported efforts to improve recruitment outcomes. • The CoP model may be adopted by donor recruitment organizations, donor registries, and blood banks worldwide to improve recruitment outcomes.

Improved survival for young acute leukemia patients following a new donor hierarchy for allogeneic hematopoietic stem cell transplantation: A phase III randomized controlled study

The aim of our study was to evaluate the most optimal donor for young acute leukemia (AL) patients with multiple donors available for allogeneic hematopoietic stem cell transplantation (allo-HSCT), including HLA-matched sibling donors (MSDs), HLA-matched unrelated donors (URDs), haploidentical parental donors (HPDs), and haploidentical sibling donors (HSDs). From March 2008 to December 2016, 430 AL patients ≤ 35 years of age were included in the discovery, retrospective study. Patients who received transplantation from a MSD or a HSD had better 5-year OS rates compared with patients who received transplantation from a URD or a HPD. A superior graft-versus-leukemia effect was observed for high-risk patients undergoing HSD-HSCT with a lower relapse rate (p = 0.014) and a higher disease-free survival (DFS) rate (p = 0.029) compared with those undergoing MSD-HSCT. Outcomes of high-risk patients receiving an URD or HPD were equivalent. For intermediate/standard-risk patients, either a MSD or HSD may be the front-line donor selection with comparable outcomes. HLA-matched unrelated donors were preferred over HPDs with reduced non-relapse mortality and higher overall survival (OS) and DFS rates. We further conducted an independent prospective randomized study to evaluate the survival advantage with the new donor hierarchy. Two hundred and fifty patients were randomly assigned to follow our new donor hierarchy or the traditional donor hierarchy at a 2:1 ratio. The new donor hierarchy contributed to significantly superior 2-year OS and DFS rates (OS: 76.2% vs. 67.8%, p = 0.046; DFS: 71.8% vs. 64.5%, p = 0.039).

Improved outcome in children compared to adolescents and young adults after allogeneic hematopoietic stem cell transplant for acute myeloid leukemia: a retrospective study from the Francophone Society of Bone Marrow Transplantation and Cell Therapy (SFGM-TC)

Background

There are currently few data on the outcome of acute myeloid leukemia (AML) in adolescents after allogeneic HSCT. The aim of this study is to describe the outcome and its specific risk factors for children, adolescents and young adults after a first allogeneic HSCT for AML.

Methods

In this retrospective study, we compared the outcome of AML patients receiving a first allogeneic HSCT between 2005 and 2017 according to their age at transplantation’s time: children (< 15 years, n = 564), adolescent and post-adolescent (APA) patients (15–25 years, n = 647) and young adults (26–40 years; n = 1434).

Results

With a median follow-up of 4.37 years (min–max 0.18–14.73 years), the probability of 2-year overall survival (OS) was 71.4% in children, 61.1% in APA patients and 62.9% in young adults (p = 0.0009 for intergroup difference). Both relapse and non-relapse mortality (NRM) Cumulative Incidence (CI) estimated at 2 years were different between the age groups (30.8% for children, 35.2% for APA patients and 29.4% for young adults—p = 0.0254, and 7.0% for children, 10.6% for APA patients and 14.2% for young adults, p < 0.0001; respectively). Whilst there was no difference between the three groups for grade I to IV acute GVHD CI at 3 months, the chronic GVHD CI at 2 years was higher in APA patients and young adults (31.4% and 36.4%, respectively) in comparison to the children (17.5%) (p < 0.0001). In multivariable analysis, factors associated with death were AML cytogenetics (HR1.73 [1.29–2.32] for intermediate risk 1, HR 1.50 [1.13–2.01] for intermediate risk 2, HR 2.22 [1.70–2.89] for high cytogenetics risk compared to low risk), use of TBI ≥ 8 Grays (HR 1.33 [1.09–1.61]), disease status at transplant (HR 1.40 [1.10–1.78] for second Complete Remission (CR), HR 2.26 [1.02–4.98] for third CR and HR 3.07 [2.44–3.85] for active disease, compared to first CR), graft source (HR 1.26 [1.05–1.50] for Peripheral Blood Stem Cells compared to Bone Marrow) and donor age (HR 1.01 (1–1.02] by increase of 1 year).

Conclusion

Age is an independent risk factor for NRM and extensive chronic GVHD. This study suggests that APA patients with AML could be beneficially treated with a chemotherapy-based MAC regimen and bone marrow as a stem cells source.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03761-w.

American Society for Transplantation and Cellular Therapy Series: #3-Prevention of Cytomegalovirus Infection and Disease After Hematopoietic Cell Transplantation

The Practice Guidelines Committee of the American Society for Transplantation and Cellular Therapy partnered with its Transplant Infectious Disease Special Interest Group to update its 2009 compendium-style infectious diseases guidelines for the care of hematopoietic cell transplant (HCT) recipients. A new approach was taken with the goal of better serving clinical providers by publishing each standalone topic in the infectious disease series as a concise format of frequently asked questions (FAQ), tables, and figures. Adult and pediatric infectious disease and HCT content experts developed and answered FAQs. Topics were finalized with harmonized recommendations that were made by assigning an A through E strength of recommendation paired with a level of supporting evidence graded I through III. The third topic in the series focuses on the prevention of cytomegalovirus infection and disease in HCT recipients by reviewing prophylaxis and preemptive therapy approaches; key definitions, relevant risk factors, and diagnostic monitoring considerations are also reviewed.