Comparison of haploidentical and umbilical cord blood transplantation after myeloablative conditioning

Improving Unrelated Donor Equity: Assessing Mismatched Donor Opportunities with Real-World Data in a Minority-Predominant Cohort

Recent advances in graft-versus-host disease (GVHD) prophylaxis including post-transplant cyclophosphamide (PTCy) and abatacept have significantly improved outcomes following HLA-mismatched allogenic hematopoietic stem cell transplantation (allo-HSCT) and have tremendous potential for reducing racial disparities in donor availability. A recent small study employing bone marrow as the source of stem cells showed similar outcomes after 5/8 versus 7/8 matches and is currently being tested in a larger study using peripheral blood stem cells. In this study, we examine real-world alternative donor HSCT options for a minority-predominant cohort in the Bronx, NY, focusing on the availability of lesser-matched (5/8 to 7/8) donors. Records of patients who underwent HLA typing at Montefiore Medical Center (2019 to 2022) were reviewed. The National Marrow Donor Program registry was queried to evaluate the availability of donors with at least 99% likelihood of HLA match at various levels (5/8, 6/8, 7/8, 8/8). Two hundred forty-one patients were included, 70% were non-White. Although the availability of ≥7/8 donors was less common in non-White patients, 100% of patients from each group had at least one or more 5/8 and 6/8 HLA-matched donors and more than 80% of these patients had >100 potential 5/8 and 6/8 HLA-matched donors. There was no statistical difference by race or ethnicity in the mean number of donors at 5/8 and 6/8 HLA-match levels. We demonstrate through real-world data that patients from diverse ethnic and racial backgrounds have access to 5/8 and 6/8 HLA-matched donors for allo-HSCT, potentially eliminating disparities in donor availability and allowing prioritization of other donor selection characteristics such as donor age, sex, ABO, and B leader matching. Further work is needed to study whether the use of mismatched donors offers a more potent graft-versus malignancy effect and optimal GVHD prophylaxis.

Machine Learning Prediction Model for Neutrophil Recovery after Unrelated Cord Blood Transplantation

Delayed neutrophil recovery is an important limitation to the administration of cord blood transplantation (CBT) and leaves the recipient vulnerable to life-threatening infection and increases the risk of other complications. A predictive model for neutrophil recovery after single-unit CBT was developed by using a machine learning method, which can handle large and complex datasets, allowing for the analysis of massive amounts of information to uncover patterns and make accurate predictions. Japanese registry data, the largest real-world dataset of CBT, was selected as the data source. Ninety-eight variables with observed values for >80% of the subjects known at the time of CBT were selected. Model building was performed with a competing risk regression model with lasso penalty. Prediction accuracy of the models was evaluated by calculating the area under the receiver operating characteristic curve (AUC) using a test dataset. The primary outcome was neutrophil recovery at day (D) 28, with recovery at D14 and D42 analyzed as secondary outcomes. The final cord blood engraftment prediction (CBEP) models included 2991 single-unit CBT recipients with acute leukemia. The median AUC of a D28-CBEP lasso regression model run 100 times was .74, and those for D14 and D42 were .88 and .68, respectively. The predictivity of the D28-CBEP model was higher than that of 4 different legacy models constructed separately. A highly predictive model for neutrophil recovery by 28 days after CBT was constructed using machine learning techniques; however, identification of significant risk factors was insufficient for outcome prediction for an individual patient, which is necessary for improving therapeutic outcomes. Notably, the prediction accuracy for post-transplantation D14, D28, and D42 decreased, and the model became more complex with more associated factors with increased time after transplantation.

Impact of CD34 positive cell dose in donor graft on the outcomes after haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide - A retrospective single-center study with a Japanese cohort

BACKGROUND

Haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) with post-transplant cyclophosphamide (PTCy) is an important therapeutic option for patients lacking an HLA-matched donor. However, the significance of CD34+ cell dose in grafts has not been fully elucidated.

OBJECTIVE

We aimed to explore the impact of CD34+ cell dose on outcomes after haplo-PBSCT with PTCy.

STUDY DESIGN

We retrospectively investigated 111 consecutive patients who underwent haplo-PBSCT with PTCy or HLA-matched PBSCT from related donors.

RESULTS

There were no statistically significant differences in 3-year overall survival (p = 0.559) or progression-free survival (p = 0.974) between haplo-PBSCT and matched PBSCT. Delayed neutrophil engraftment and a lower incidence of graft-versus-host disease were observed in haplo-PBSCT. The median dose of CD34+ cells was 4.9 × 106 /kg in 57 haplo-PBSCT and 4.5 × 106 /kg in 54 matched PBSCTs. Importantly, patients who underwent haplo-PBSCT with the administration of CD34+ cell at a dose of ≥4.0 × 106 /kg significantly had improved OS (p = 0.015) and decreased incidence of disease relapse (p = 0.001) without increasing incidence of GVHD.

CONCLUSION

Our data suggest that a higher dose of CD34+ cells in haplo-PBSCT with PTCy positively impacts the outcomes without an increase of GVHD.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Human Leukocyte Antigen-Haploidentical Haematopoietic Stem Cell Transplantation Using Post-Transplant Cyclophosphamide for Paediatric Haematological Malignancies

The use of human leukocyte antigen (HLA)-haploidentical haematopoietic stem cell transplantation (HSCT) with post-transplant cyclophosphamide (PTCY), which markedly reduces the risk of graft-versus-host disease, has rapidly increased worldwide, even in children. It was initially developed for post-transplant relapse or non-remission at transplant for patients with high-risk haematologic malignancies. However, this strategy is currently used more frequently for standard-risk, transplant-eligible paediatric haematological malignancies. It has recently been recognised in adults that the transplant outcomes after PTCY-based HLA-haploidentical HSCT are comparable with those achieved after HLA-matched HSCT. Therefore, even in children, parental donors who are HLA-haploidentical donors and cord blood are currently considered the next donor candidates when an HLA-matched related or unrelated donor is unavailable. This review addresses the current status of the use of haplo-HSCT with PTCY for paediatric haematologic malignancies and future directions for donor selection (sex, age, ABO blood type, and HLA disparity), donor source, the dose of infused CD34+ cells, optimal conditioning, the concomitant graft-versus-host disease prophylaxis other than PTCY, and the pharmacokinetic study of CY and CY metabolites. These aspects present key solutions for further improvements in the outcomes of haplo-HSCT with PTCY for paediatric haematological malignancies.

Immunology of cord blood T-cells favors augmented disease response during clinical pediatric stem cell transplantation for acute leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) has been an important and efficacious treatment for acute leukemia in children for over 60 years. It works primarily through the graft-vs.-leukemia (GVL) effect, in which donor T-cells and other immune cells act to eliminate residual leukemia. Cord blood is an alternative source of stem cells for transplantation, with distinct biological and immunological characteristics. Retrospective clinical studies report superior relapse rates with cord blood transplantation (CBT), when compared to other stem cell sources, particularly for patients with high-risk leukemia. Xenograft models also support the superiority of cord blood T-cells in eradicating malignancy, when compared to those derived from peripheral blood. Conversely, CBT has historically been associated with an increased risk of transplant-related mortality (TRM) and morbidity, particularly from infection. Here we discuss clinical aspects of CBT, the unique immunology of cord blood T-cells, their role in the GVL effect and future methods to maximize their utility in cellular therapies for leukemia, honing and harnessing their antitumor properties whilst managing the risks of TRM.

PTCy, abatacept, and a short course of tacrolimus for GVHD prevention after haploidentical transplantation

Reducing the incidence of graft-versus-host disease (GVHD) after haploidentical hematopoietic stem cell transplantation (HSCT) is warranted. Posttransplant cyclophosphamide (PTCy) is the main agent used for GVHD prevention in this setting. It remains unknown whether costimulation blockade can be safely combined with PTCy and enhance its efficacy. We performed a phase 1b-2 clinical trial to examine the combination of PTCy, abatacept, and a short course of tacrolimus (CAST) after peripheral blood haploidentical HSCT. The primary end point was the incidence of grades 2-4 acute GVHD by day +120. The study enrolled 46 patients with a median age of 60 years (range, 18-74 years). The cumulative incidences of grades 2-4 and 3 or 4 acute GVHD were 17.4% (95% confidence interval [CI], 9.2-32.9) and 4.4% (95% CI, 1.1-17.1), respectively. With a median follow-up of 15.3 months, the cumulative incidence of 1-year treatment-related mortality was 4.4% (95% CI, 1.1-17.1). The estimated 1-year moderate-to-severe chronic GVHD rate, relapse rate, progression-free survival, overall survival, and GVHD- and relapse-free survival were 15.9% (95% CI, 8-31.7), 11.7% (95% CI, 5-27.2), 84.1% (95% CI, 73.8-95.7), 85.9% (95% CI, 75.9-97.2), and 66.1% (95% CI, 53.4-81.8), respectively. Toxicities were similar to those expected in patients receiving haploidentical HSCT. This clinical trial showed that the CAST regimen is safe and effective in reducing the rate of grades 2-4 acute GVHD after haploidentical peripheral blood HSCT. This trial was registered at www.clinicaltrials.gov as #NCT04503616.

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

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

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

BACKGROUND

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

In 2022, which is preferred: haploidentical or cord transplant?

Allogeneic hematopoietic stem cell transplantation is the treatment of choice for high-risk hematological malignancies such as acute myeloid and lymphocytic leukemia, myelodysplastic syndrome, and myeloproliferative disorders. Alternative donor transplantation from either haploidentical (haplo-SCT) or cord blood donor (CBT) is an established therapeutic alternative for patients who need transplants but lack a human leukocyte antigen-matched donor. Although haplo-SCT (mainly non-T-cell-depleted haplo-SCT with posttransplant cyclophosphamide) is increasing while CBT is decreasing worldwide (Figure 1), recent developments in CBT, especially cord blood expansion and other strategies to improve engraftment and immune reconstitution post-CBT, make CBT still a valuable option. This article discusses the 2 options based on the currently available data, focusing on adults, and tries to give some clues to help the transplant physician choose a haploidentical vs a cord blood donor. Given the limited numbers of published or ongoing well-designed randomized controlled trials comparing haplo-SCT to CBT and the overall similar clinical results in the available, mostly registry-based, and single-center studies, with substantial heterogeneity and variability, the decision to perform haplo-SCT or CBT in a given patient depends not only on the patient, disease, and donor characteristics and donor availability (although most if not all patients should have in principle an alternative donor) but also on the transplant physician's discretion and, most importantly, the center's experience and preference and ongoing protocols and strategies.

Haplo-Peripheral Blood Stem Cell Plus Cord Blood Grafts for Hematologic Malignancies Might Lead to Lower Relapse Compared with Haplo-Peripheral Blood Stem Cell Plus Bone Marrow Grafts

To compare the outcomes between peripheral blood stem cell (PBSC)+cord blood and PBSC+bone marrow (BM) grafts in the setting of haploidentical donor (HID) transplantation, 110 patients were enrolled in this retrospective study, including 54 recipients of haplo-PBSC+cord transplants and 56 recipients of haplo-PBSC+BM transplants. Chimerism analyses revealed that by day 30 post-transplantation, 94.3% of surviving patients in the haplo-PBSC+cord group had achieved full haploidentical chimerism and 5.7% had <10% cord chimerism, whereas 100% of surviving patients in the haplo-PBSC+BM group had achieved full donor chimerism. The cumulative incidence of platelet engraftment at 30 days was 92.6% in the haplo-PBSC+cord group versus 89.3% in the haplo-PBSC+BM group (P =.024), that of grade II-IV acute graft-versus-host disease (GVHD) at 100 days was 31.5% versus 48.2% (P =.060), and 1-year relapse was 13.0% versus 25.0% (P =.027), nonrelapse mortality was 9.3% versus 12.5% (P =.76), disease-free survival (DFS) was 77.7% versus 62.5% (P =.028), and overall survival (OS) was 81.4% versus 69.6% (P =.046). Multivariate analysis identified haplo-PBSC+cord transplantation as a protective factor for relapse (hazard ratio [HR], .31; P =.007), DFS (HR, .40; P =.007), and OS (HR, .44; P =.016). Overall, haplo-PBSC+cord transplantation led to faster platelet engraftment, lower relapse, and superior DFS and OS compared with haplo-PBSC+BM transplantation and thus might be a better transplant mode in the setting of HID transplantation.

Umbilical cord blood: an undervalued and underutilized resource in allogeneic hematopoietic stem cell transplant and novel cell therapy applications

PURPOSE OF REVIEW

The purpose of this review is to primarily discuss the unwarranted decline in the use of umbilical cord blood (UCB) as a source of donor hematopoietic stem cells (HSC) for hematopoietic cell transplantation (HCT) and the resulting important implications in addressing healthcare inequities, and secondly to highlight the incredible potential of UCB and related birthing tissues for the development of a broad range of therapies to treat human disease including but not limited to oncology, neurologic, cardiac, orthopedic and immunologic conditions.

RECENT FINDINGS

When current best practices are followed, unrelated donor umbilical cord blood transplant (CBT) can provide superior quality of life-related survival compared to other allogeneic HSC donor sources (sibling, matched or mismatched unrelated, and haploidentical) through decreased risks of relapse and chronic graft vs. host disease. Current best practices include improved UCB donor selection criteria with consideration of higher resolution human leukocyte antigen (HLA) typing and CD34+ cell dose, availability of newer myeloablative but reduced toxicity conditioning regimens, and rigorous supportive care in the early posttransplant period with monitoring for known complications, especially related to viral and other infections that may require intervention. Emerging best practice may include the use of ex vivo expanded single-unit CBT rather than double-unit CBT (dCBT) or 'haplo-cord' transplant, and the incorporation of posttransplant cyclophosphamide as with haploidentical transplant and/or incorporation of novel posttransplant therapies to reduce the risk of relapse, such as NK cell adoptive transfer. Novel, non-HCT uses of UCB and birthing tissue include the production of UCB-derived immune effector cell therapies such as unmodified NK cells, chimeric antigen receptor-natural killer cells and immune T-cell populations, the isolation of mesenchymal stem cells for immune modulatory treatments and derivation of induced pluripotent stem cells haplobanks for regenerative medicine development and population studies to facilitate exploration of drug development through functional genomics.

SUMMARY

The potential of allogeneic UCB for HCT and novel cell-based therapies is undervalued and underutilized. The inventory of high-quality UCB units available from public cord blood banks (CBB) should be expanding rather than contracting in order to address ongoing healthcare inequities and to maintain a valuable source of cellular starting material for cell and gene therapies and regenerative medicine approaches. The expertise in Good Manufacturing Practice-grade manufacturing provided by CBB should be supported to effectively partner with groups developing UCB for novel cell-based therapies.

Haploidentical peripheral blood stem cell transplantation combined with unrelated cord blood in hematologic malignancy patients: A report of 80 cases

The outcomes of 80 patients with hematologic malignancies who received haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) combined with unrelated cord blood (UCB) from March 2017 to June 2020 were analyzed in this retrospective study. Anti-thymocyte globulin(ATG) was administered at a dose of 7.5 mg/kg. The median time for neutrophil and platelet engraftment was 13(range: 8-22) days and 14(range: 8-103) days, respectively. The 30-day cumulative incidence of neutrophil engraftment was 100%, and the 100-day cumulative incidence of platelet engraftment was 95%. All patients achieved complete haploidentical peripheral blood stem cell engraftment, and no cord blood chimerism was observed. The cumulative incidence of grades II-IV and grades III-IV acute graft-versus-host disease (aGVHD) on 100-day was 26.3%(95%CI: 17.2%–36.3%) and 5.0%(95%CI: 1.6%–11.4%), respectively. The estimated cumulative incidence of chronic GVHD (cGVHD) and moderate-severe cGVHD at 3-year was 43.3%(95%CI: 31.6%–54.4%) and 16.0%(95%CI: 8.7%–25.2%), respectively. The estimated 3-year cumulative incidence of relapse and non-relapse mortality was 18.8%(95%CI: 10.0%–29.7%) and 17.8%(95%CI: 9.9%–27.5%), respectively. The estimated 3-year probabilities of overall survival, disease-free survival, GVHD/relapse-free survival were 77.6%(95%CI: 68.3%–88.1%), 63.4%(95%CI: 52.6%–76.5%), and 55.5%(95%CI: 44.8%–68.7%), respectively. These satisfying results suggested that haplo-PBSCT combined with UCB is an alternative transplantation protocol for hematologic malignancies.

Strategies for Success With Umbilical Cord Haematopoietic Stem Cell Transplantation in Children With Malignant and Non-Malignant Disease Indications

Umbilical Cord blood is an intuitively attractive stem cell source, but its use has declined since it is associated with an increased procedure-related morbidity and transplant related mortality. Some of this reflects that cord blood transplants are more often HLA-mismatched compared to other unrelated donor transplants. The ability to transplant in such a setting, indeed without high rates of chronic Graft versus Host Disease (GVHD), constitutes an advantage compared to other unrelated donor cell sources and there are other advantages specifically associated with cord blood as a donor cell source. These advantages must be weighed against its disadvantage, and we have utilised cord blood preferentially as a donor cell source in certain clinical situations in paediatric medicine. In non-malignant diseases, outcomes in metabolic disease are critically dependent on age at transplant and the enzyme delivered by that transplant, and in cord blood transplantation then the time to transplant can be minimised and the engrafted recipients have higher chimerism that delivers higher enzyme levels. In malignant diseases, studies have described reduced relapse rate and better GVHD-free survival, and so we have prioritised cord as a donor cell source where the risk of relapse is highest, and the effects of higher transplant related mortality is most clearly offset by the reduced relapse rates.