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

Older MRD vs. younger MUD in patients older than 50 years with AML in remission using post-transplant cyclophosphamide

An increasing number of older patients with acute myeloid leukemia (AML) are offered an allogeneic hematopoietic stem cell transplantation (allo-HSCT). Normally, older patients have older matched related donors (MRD). Matched unrelated donors (MUD) are an important alternative, but it remains unclear whether a younger MUD is associated with better outcomes, especially in the context of post-transplant cyclophosphamide (PTCy). We compared outcomes of patients older than 50 years with AML in first complete remission (CR1) and receiving a first HSCT from a 10/10 MUD aged younger than 40 years to those receiving a graft from a MRD aged older than 50 years, using PTCy and with well-known transplant conditioning intensity (TCI) score. A total of 345 consecutive patients were included and classified according to TCI score as low, intermediate, or high. On multivariable analysis in the TCI-intermediate/high group, MUD was associated with better graft-versus-host disease-free, relapse-free survival, lower non-relapse mortality and lower relapse incidence. For patients receiving a TCI-low regimen, outcomes are independent on the type of donor. In patients with AML in CR1, older than 50 years and receiving a TCI-intermediate/high conditioning regimen using PTCy, a MUD younger than 40 years is preferable over a MRD older than 50 years.

Unrelated hematopoietic stem cell donor registries: present reality and future prospects

PURPOSE OF REVIEW

Stem cell donor registries play an important role in providing stem cell products from unrelated donors to patients with severe blood diseases. In this review, important aspects of donor registry work, current challenges and possible future developments are discussed.

RECENT FINDINGS

The current growth in global unrelated stem cell donations is in line with the long-term trend, indicating that donor registries have overcome the COVID-19 pandemic. A key challenge for donor registries is the recruitment of donors from disadvantaged populations to create greater equity in access to unrelated stem cell transplantation. In addition, recruiting young donors and increasing the availability of donors who are already registered are important goals. In recent years, numerous studies have looked at the context of these themes and the development of possible solutions.

SUMMARY

The international community of donor registries, together with the World Marrow Donor Association, has helped many patients in need of a stem cell transplant over the past decades and is, therefore, a bright example of international collaboration for a good cause. It is currently addressing a number of challenges to effectively help as many patients as possible from various populations also in the future.

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.

Optimizing Outcomes in Mismatched Unrelated Donor Allogeneic Transplantation: Post-Transplant Cyclophosphamide's Dual Impact on Graft versus Host Disease Incidence and Overall Survival: Retrospective Analysis on Behalf of Polish Adult Leukemia Group

Allogeneic hematopoietic cell transplantation (allo-HSCT) stands as an effective treatment method for various hematologic malignancies. However, graft-versus-host disease (GvHD), an intricate immunological phenomenon where donor immune cells target recipient tissues, remains a significant challenge, particularly in mismatched unrelated donors (MMUD). Post-transplant cyclophosphamide (PTCy) has emerged as a promising immunosuppressive strategy, revolutionizing haploidentical transplantation and demonstrating promise in MMUD settings. Background/Objectives: This study aimed to evaluate the impact of PTCy on MMUD allo-HSCT outcomes, specifically its effects on GvHD incidence and overall survival, compared to anthitymocyte globulin (ATG). Methods: One hundred seventy-four patients were classified into three groups based on the type of transplantation: PTCy-haplo (114/174; 65.5%), PTCy-MMUD (23/174; 13.2%), and ATG-MMUD (37/174; 21.2%). Results: Our findings showed that PTCy-MMUD significantly reduced acute GvHD occurrence compared to PTCy-haplo and ATG-MMUD approaches (p = 0.006). The delayed onset of acute GvHD in the PTCy-MMUD group suggests a more controlled immune reconstitution, contributing to the lower incidence. Importantly, PTCy-MMUD exhibited enhanced five-year overall survival rates, aligning with the notion that reduced GvHD correlates with improved patient outcomes (p = 0.032). Conclusions: We believe that this study contributes valuable insights into PTCy-MMUD's management, underscoring its potential to significantly reduce GvHD incidence and enhance survival outcomes. Although further investigations and clinical trials are warranted, this research underscores the promising role of PTCy-based GvHD prophylaxis in improving MMUD allo-HCT success.

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.

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.

Deciphering aging-associated molecular mechanisms in bone marrow derived hematopoietic stem cells in the elderly using NGS data

Aging is a complex process that is not yet fully understood. Despite advancements in research, a deeper understanding of the underlying biological mechanisms is necessary to develop interventions that promote healthy longevity. The aim of this study was to elucidate the complex mechanisms associated with healthy aging and longevity in healthy elderly individuals. The RNA sequencing (RNA-seq) data used in this study was obtained from the Gene Expression Omnibus (GEO) database (accession number GSE104406), which was collected from Fluorescent Activated Cell Sorting (FACS) of human bone marrow derived human hematopoietic stem cells (BM-HSCs) (Lineage-, CD34+, CD38-) young (18-30 years old) and aged (65-75 years old) donors who had no known hematological malignancy, with 10 biological replicates per group. The GEO RNA-seq Experiments Interactive Navigator (GREIN) software was used to obtain raw gene-level counts and filtered metadata for this dataset. Next generation knowledge discovery (NGKD) tools provided by BioJupies were used to obtain differentially regulated pathways, gene ontologies (GO), and gene signatures in the BM-HSCs. Finally, the L1000 Characteristic Direction Signature Search Engine (L1000CDS2) tool was used to identify specific drugs that reverse aging-associated gene signatures in old but healthy individuals. The down-regulation of signaling pathways such as longevity regulation, proteasome, Notch, apoptosis, nuclear factor kappa B (NFkB), and peroxisome proliferator-activated receptors (PPAR) signaling pathways in the BM-HSCs of healthy elderly. GO functions related to negative regulation of bone morphogenetic protein (BMP), telomeric DNA binding, nucleoside binding, calcium -dependent protein binding, chromatin-DNA binding, SMAD binding, and demethylase activity were significantly downregulated in the BM-HSCs of the elderly compared to the healthy young group. Importantly, potential drugs such as salermide, celestrol, cercosporin, dorsomorphin dihydrochloride, and LDN-193189 monohydrochloride that can reverse the aging-associated signatures in HSCs from healthy elderly were identified. The analysis of RNA-seq data based on NGKD techniques revealed a plethora of differentially regulated pathways, gene ontologies, and drugs with anti-aging potential to promote healthspan in the elderly.

Efficacy of SARS-CoV-2 Vaccine Doses in Allogeneic Hemopoietic Stem Cell Recipients: A Systematic Review and Meta-Analysis

OBJECTIVE

Recipients of allogeneic hematopoietic cell transplantation (alloHCT) are at increased risk of morbidity and mortality due to COVID-19. Immune responses to SARS-CoV-2 vaccines are blunted in these profoundly immunocompromised patients. As a result, novel strategies for protection, such as additional vaccine doses (boosters), are being explored. However, data regarding the efficacy of a third dose of SARS-CoV-2 vaccine in alloHCT recipients are limited and conflicting.

METHODS

In this systematic review and meta-analysis, we investigated the efficacy of a third dose of SARS-CoV-2 vaccine in alloHCT recipients. The review was conducted following PRISMA guidelines, and 7 studies with 385 alloHCT recipients who received 3 vaccine doses were included. The primary outcomes assessed were the rate of seroconversion following the third dose of vaccine and the rate of seroconversion in patients who did not respond to the initial 2-dose vaccination series.

RESULTS

The pooled humoral response rate after 3 doses of SARS-CoV-2 vaccine in alloHCT recipients was 74%. In a subgroup analysis of patients who did not respond to the initial 2-dose series, the seroconversion rate following the third vaccine dose was 49%. Notably, male patients and those with a shorter interval between alloHCT and the first vaccine dose were more likely to not respond to the third dose.

CONCLUSION

In conclusion, the pooled humoral response rate of 74% following three doses of SARS-CoV-2 vaccine in alloHCT recipients highlights the potential for protection in this immunosuppressed population. Additionally, encouraging responses in nearly half of the patients who did not seroconvert with the initial 2-dose series suggest the continued utilization of additional vaccine doses until results from large prospective studies become available. These findings are critical for informing vaccination strategies in alloHCT recipients to mitigate the high mortality risk associated with COVID-19.

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

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