The European Society for Blood and Marrow Transplantation (EBMT) consensus recommendations for donor selection in haploidentical hematopoietic cell transplantation

Future directions in haploidentical hematopoietic stem cell transplantation

Outcomes of haploidentical hematopoietic stem cell transplantation (haplo-SCT) have improved over time. Graft failure and graft-versus-host disease (GVHD), which were important complications in major human leukocyte antigen (HLA)-disparity stem cell transplantation, have significantly decreased. These improvements have led to an exponential increase in the use of haploidentical donors for transplantation, as well as in the number of publications evaluating haplo-SCT outcomes. Many studies focused on factors important in donor selection, novel conditioning regimens or GVHD prophylaxis, the impact of donor-specific anti-HLA antibodies (DSA), as well as strategies to prevent disease relapse post-transplant. DSA represents an important limitation and multimodality desensitization protocols, including plasma exchange, rituximab, intravenous immunoglobulin and donor buffy coat infusion, can contribute to the successful engraftment in patients with high DSA levels and is currently the standard therapy for highly allosensitized individuals. With regards to donor selection, younger donors are preferred due to lower risk of complications and better transplant outcomes. Moreover, recent studies also showed that younger haploidentical donors may be a better choice than older-matched unrelated donors. Improvement of disease relapse remains a top priority, and several studies have demonstrated that higher natural killer (NK) cell numbers early post-transplant are associated with improved outcomes. Prospective studies have started to assess the role of NK cell administration in decreasing post-transplant relapse. These studies suggest that the incorporation of other cell products post-transplant, including the administration of chimeric antigen receptor T-cells, should be explored in the future.

Human NK cells and cancer

The long story of NK cells started about 50 y ago with the first demonstration of a natural cytotoxic activity within an undefined subset of circulating leukocytes, has involved an ever-growing number of researchers, fascinated by the apparently easy-to-reach aim of getting a "universal anti-tumor immune tool". In fact, in spite of the impressive progress obtained in the first decades, these cells proved far more complex than expected and, paradoxically, the accumulating findings have continuously moved forward the attainment of a complete control of their function for immunotherapy. The refined studies of these latter years have indicated that NK cells can epigenetically calibrate their functional potential, in response to specific environmental contexts, giving rise to extraordinarily variegated subpopulations, comprehensive of memory-like cells, tissue-resident cells, or cells in various differentiation stages, or distinct functional states. In addition, NK cells can adapt their activity in response to a complex body of signals, spanning from the interaction with either suppressive or stimulating cells (myeloid-derived suppressor cells or dendritic cells, respectively) to the engagement of various receptors (specific for immune checkpoints, cytokines, tumor/viral ligands, or mediating antibody-dependent cell-mediated cytotoxicity). According to this picture, the idea of an easy and generalized exploitation of NK cells is changing, and the way is opening toward new carefully designed, combined and personalized therapeutic strategies, also based on the use of genetically modified NK cells and stimuli capable of strengthening and redirecting their effector functions against cancer.

Graft-versus-tumor effect of post-transplant cyclophosphamide-based allogeneic hematopoietic cell transplantation

Post-transplant cyclophosphamide (PTCy) is becoming the standard prophylaxis for graft-versus-host disease (GVHD) in HLA-haploidentical allogeneic hematopoietic cell transplantation (allo-HCT) and in HLA-matched allo-HCT. Immune reconstitution in the post-transplant setting may influence the graft-versus-tumor (GVT) effect because PTCy has a profound effect on T cell and natural killer cell functions and their reconstitution after allo-HCT. However, many recent studies have shown that the incidence of relapse after allo-HCT with PTCy is comparable to that after conventional allo-HCT. To further improve the outcomes, it is critical to establish a strategy to maintain or effectively induce the GVT effect when using PTCy as a platform for GVHD prophylaxis. However, there is a paucity of studies focusing on the GVT effect in allo-HCT with PTCy. Therefore, focusing on this issue may lead to the establishment of more appropriate strategies to improve transplantation outcomes without exacerbating GVHD, including novel therapies involving cell modification.

Reduced intensity conditioning regimen of fludarabine, busulfan, ATG based haploidentical stem cell transplantation for older or unfit patients

Reduced-intensity conditioning (RIC) regimens allogeneic hematopoietic stem cell transplantation (HSCT) was developed for older patients or those with poor functional status. Haploidentical donor was appropriate alternative donor for patients without matched donors or patients with emergency disease state. However, there was few studies report the outcomes of RIC regimen of anti-thymocyte globulin (ATG) based haploidentical HSCT. The selection of the appropriate RIC regimen based on age and comorbidities in ATG-based haploidentical HSCT remains poorly described. To investigate the safety and efficacy of RIC regimen ATG-based haploidentical HSCT in older or unfit patients. Additionally, to explore the potential factors that impact the prognosis of RIC regimen of ATG-based haploidentical HSCT. We included a retrospective cohort of 63 patients with hematologic malignant diseases who underwent their first RIC haploidentical HSCT from November 2016 to June 2022 at our institutions. The conditioning regimen involved fludarabine (Flu) 30 mg/m²/kg 6 days combined with busulfan 3.2 mg/kg 2 days (Bu2) or 3 days (Bu3). ATG-Fresenius (ATG-F) was administered 10 mg/kg in total, ATG-thymoglobulin (ATG-T) was administered 6 mg/kg in total. The median age of patients in the entire cohort was 60 (32-67) years with a median follow-up of 496 (83-2182) days. There were 29 patients with AML, 20 patients with MDS, and 14 patients with ALL. A total of 32 patients underwent Bu2 RIC haplo-HSCT and 31 patients were treated with Bu3 RIC haplo-HSCT. The 2-year overall survival (OS) and 2-year disease-free survival (DFS) in whole cohort were 67.7% (95% confidence interval [CI], 53.8 - 85.1%) and 61.4% (95% CI, 48.8 - 77.3%) respectively. The cumulative incidence rates of grades II to IV and grades III to IV acute graft-versus-host disease (aGVHD) in whole cohort were 15.8% (95% CI, 4.8 - 19.6%) and 9.7% (95% CI, 0.0 - 11.8%) respectively. The 2-year cumulative incidence of chronic GVHD was 34.0% (95% CI, 18.9 - 46.3%). The 2-year cumulative incidence rates of relapse (IR) and non-relapse mortality (NRM) rates in whole cohort were 27.5% (95% CI, 14.5 - 33.7%) and 11.6% (95% CI, 2.2 - 21.9%) respectively. The probability of 2-year OS were 60.2% (95% CI:42.5-85.3%) in Bu2 and 85.5%(95% CI:73.0-100%) in Bu3 group respectively(P = 0.150). The probability of 2-year DFS were 49.7% (95% CI:33.0-74.8%) in Bu2 and 72.6% (95% CI:55.5-95.5%) in Bu3 group respectively (P = 0.045). The 2-year IR of Bu2 group was significantly higher than Bu3 group (P = 0.045). However, the 2-year NRM were not significantly different between Bu2 and Bu3 group(P > 0.05). In multivariable analysis, RIC regimen of Bu3 had superior OS and DFS than Bu2 group respectively [HR 0.42, 95% CI 0.18-0.98; P = 0.044; HR 0.34, 95% CI 0.14-0.86; P = 0.022]. Besides, RIC regimen of Bu3 had lower IR than Bu2 group [HR 0.34, 95% CI 0.13-0.89; P = 0.029]. The RIC regimen of ATG-based haploidentical HSCT is a safe and effective treatment option for patients who are older or have poor functional status. In particular, a relatively high-intensity pre-treatment regimen consisting of Bu achieves significant improvements in OS and DFS, thus providing more favorable post-transplantation clinical outcomes.

Strategies to reduce relapse risk in patients undergoing allogeneic stem cell transplantation for acute myeloid leukaemia

Allogeneic stem cell transplantation is a centrally important curative strategy in adults with acute myeloid leukaemia; however, relapse occurs in a significant proportion of patients and remains the leading cause of treatment failure. The prognosis for patients who relapse post-transplant remains poor, and the development of new strategies with the ability to reduce disease recurrence without increasing transplant toxicity remains a priority. In this review, within the context of our understanding of disease biology and the graft-versus-leukaemia (GVL) effect, we will discuss established, evolving and novel approaches for increasing remission rates, decreasing measurable residual disease pretransplant, future methods to augment the GVL effect and the opportunities for post-transplant maintenance. Future progress depends upon the development of innovative trials and networks, which will ensure the rapid assessment of emerging therapies in prospective clinical trials.

Donor matters: Donor selection impact on hematopoietic stem cell transplantation outcomes in Hispanic patients with B-cell acute lymphocytic leukemia: Insights from a myeloablative HSCT study

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is a pivotal treatment for high-risk acute lymphocytic leukemia (ALL), although limited by suitable human leukocyte antigen (HLA)-matched sibling donors (MSD). This study evaluates the impact of donor selection on outcomes in post-HSCT Hispanic B-cell ALL patients.

METHODOLOGY

This single-center retrospective study evaluates outcomes in 88 adult Hispanic B-cell ALL patients who underwent haploidentical, MSD, or MUD myeloablative HSCT between 2013 and 2023.

RESULTS

Compared to Haploidentical transplants, MSD exhibited worse cumulative incidence of relapse (CIR) (HR = 3.39; P = 0.014) and disease-free survival (DFS) (HR = 2.44; P = 0.048) whereas MUD outcomes did not differ. This effect persisted even when controlling for pre-HSCT stage and Minimal residual disease (MRD) status. In addition, Ph-like was a significant predictor of worse DFS (HR = 3.60; P=0.014) and CIR (HR = 2.97; P=0.035) on multivariate analysis. Older donor age correlated with worse GVHD-free, relapse-free survival (GRFS) in haploidentical transplants (HR = 1.05; P=0.036).

CONCLUSION

Our data highlights improved outcomes with younger, haploidentical donors among Hispanic B-cell ALL patients undergoing myeloablative HSCT. This underscores the importance of donor selection in optimizing outcomes for ALL patients.

Haploidentical stem cell donor choice for patients with acute myeloid leukemia: a study from the ALWP of the EBMT

ABSTRACT

There is a paucity of information to guide the selection of the most suitable donor in haploidentical (Haplo) hematopoietic stem cell transplantation (HSCT). For this reason, from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we conducted a retrospective analysis to evaluate the impact of Haplo donor characteristics on outcomes in patients with acute myeloid leukemia (AML) who received graft-versus-host disease prophylaxis with posttransplant cyclophosphamide (PTCy). The primary end point was graft-versus-host disease (GVHD)-free and relapse-free survival (GRFS). Overall, 2200 patients were included. The median age of donors was 37 years (range, 8-71); 820 (37%) were females, including 458 (21%) who were used for male recipients. In addition, 1631 donors (74%) donated peripheral blood (PB). Multivariable analysis identified certain donor-related risk factors with a detrimental impact on transplant outcomes. The use of PB, older donors' ages (>37 years), and female donors to male recipients negatively affected GRFS. Donor's age and female donor-to-male recipient combination also affected nonrelapse mortality, leukemia-free survival, and overall survival. In conclusion, donor-related variables significantly influence outcomes in patients with AML after Haplo-HSCT with PTCy. When possible, younger donors and male donors for male recipients should be prioritized. The use of bone marrow can additionally prevent GVHD.

The role and novel use of natural killer cells in graft-versus-leukemia reactions after allogeneic transplantation

Allogeneic hematopoietic cell transplantation (HCT) has transformed over the past several decades through enhanced supportive care, reduced intensity conditioning (RIC), improved human leukocyte antigen (HLA) typing, and novel graft-versus-host disease (GVHD)-prevention and treatment strategies. Most notably, the implementation of post-transplantation cyclophosphamide (PTCy) has dramatically increased the safety and availability of this life-saving therapy. Given reductions in nonrelapse mortality (NRM) with these advances, the HCT community has placed even greater emphasis on developing ways to reduce relapse - the leading cause of death after HCT. When using RIC HCT, protection from relapse relies predominantly on graft-versus-leukemia (GVL) reactions. Donor lymphocyte infusion (DLI), adoptive cellular therapy, checkpoint inhibition, and post-HCT maintenance strategies represent approaches under study that aim to augment or synergize with the GVL effects of HCT. Optimizing donor selection algorithms to leverage GVL represents another active area of research. Many of these strategies seek to harness the effects of T cells, which for decades were felt to be the primary mediators of GVL and the focus of investigation in relapse reduction. However, there is growing interest in capitalizing on the ability of natural killer (NK) cells to yield potent anti-tumor effects. A potential advantage of NK cell-based approaches over T cell-mediated is the potential to reduce NRM in addition to relapse. By decreasing infection, without increasing the risk of GVHD, NK cells may mitigate NRM, while still yielding relapse reduction through identification and clearance of cancer cells. Most T cell-focused relapse-prevention strategies must weigh the benefits of relapse reduction against the increased risk of NRM from GVHD. In contrast, NK cells have the potential to reduce both, potentially tipping the scales significantly in favor of survival. Here, we will review the role of NK cells in GVL, optimization of NK cell match or mismatch, and burgeoning areas of research in NK cell therapy such as adoptive transfer and chimeric antigen receptor (CAR) NK cells.

Clinical significance of decreased or loss of ABO blood group expression in acute myeloid leukaemia: A single-centre retrospective study

BACKGROUND AND OBJECTIVES

Decreased or loss of ABO blood group antigen expression has been observed in acute myeloid leukaemia (AML) patients. We studied the clinical significance of this group in AML patients.

MATERIALS AND METHODS

This was a retrospective, single-centre cohort study in which the data were retrieved from April 2009 to December 2019. A total of 1592 AML patients with normal ABO blood group antigen (Group I) and 65 patients of decreased or loss of ABO blood group antigen (Group II) group were enrolled. Data were collected at the time of initial admission for pathological diagnosis. To interrogate the underlying mechanism, publicly available The Cancer Genome Atlas AML data were downloaded.

RESULTS

Group II consisted of 3.9% (65/1657) of AML patients. The 90-day survival (D90) probability was higher for Group II with a mean survival of 86.4 days compared to 80.6 days for Group I (p = 0.047). Group II had higher haematocrit (28.6 vs. 27.4%) and lower d-dimer, fibrinogen degradation production and C-reactive protein. Publicly available data revealed that among 11 CpG methylation sites within the ABO gene, 4 sites with elevated methylation level were associated with improved D90 survival probability and demonstrated an inverse correlation with ABO gene expression. Lower expression of the ABO gene showed improved survival trends for D90 (p = 0.058) and 180-day survival (p = 0.072).

CONCLUSION

AML with decreased expression or loss of ABO blood group showed better early survival during D90. Transfusion support for this subgroup of AML patients should be meticulously performed considering serum typing.

HLA Haplotypes and Relapse After Hematopoietic Cell Transplantation

PURPOSE

Recurrence of blood malignancy is the major cause of hematopoietic cell transplant failure. HLA class II molecules play a fundamental role in antitumor responses but the role of class II haplotypes is not known.

METHODS

HLA-DR, -DQ, -DM, and -DO allele variation was determined in 1,629 related haploidentical transplants to study the clinical significance of individual molecules and haplotypes.

RESULTS

Outcome correlated with patient and donor variation for HLA-DRβ residue 86 (Gly/Val), HLA-DQ (G1/G2) heterodimers, and donor HLA-DM (DM11,11/nonDM11,11) molecules, and depended on patient-donor mismatching. Risks of relapse were lower for DRβ-86 GlyGly patients when the donor was GlyVal (hazard ratio [HR], 0.46 [95% CI, 0.30 to 0.68]; P < .001); GlyVal patients benefited from HLA-DRB1-matched donors, whereas no donor was superior to another for ValVal patients. G1G2 patients with G1G2-mismatched donors had lower relapse. Transplantation from donors with DMα residue 184 ArgHis was associated with higher risk of relapse (HR, 1.60 [95% CI, 1.09 to 2.36]; P = .02) relative to ArgArg. Relapse and mortality risks differed across HLA-DR-DQ-DM haplotypes.

CONCLUSION

HLA class II haplotypes may be functional constituents of the transplantation barrier, and their consideration in patients and donors may improve the success of transplantation.

Allogeneic hematopoietic stem cell transplantation: A single-center experience, 2017 to 2021

INTRODUCTION

Hematopoietic stem cell transplantation (HSCT) remains a critical treatment for advanced or high-risk hematological malignancies, posing challenges such as finding suitable donors and managing of graft-versus-host disease (GvHD). This study estimates 3-year overall survival in patients who underwent HSCT at our referral service in the state of Minas Gerais, Brazil.

MATERIAL AND METHODS

This retrospective observational cohort study involved 41 patients who received HSCT between 2017 and 2021 at the Felício Rocho Hospital. Recipients received HSCT from either haploidentical donor (Haplo), matched unrelated donor (MUD), or HLA-matched sibling donor (MSD). The study evaluated parameters that included 3-year overall survival (OS), treatment-related mortality (TRM), GvHD incidence, post-transplant relapse rate, and engraftment. ANOVA, Kruskal-Wallis, and chi-square tests were used for statistical analysis. Survival curves were calculated using the Kaplan-Meier method and the Log-rank test compared the curves.

RESULTS

Our study found that the engraftment time differed among groups: Haplo recipients engrafted earlier within a median of 16 days (ranging between 10 and 20 days) than MSD recipients with 18 days (ranging between 11 and 28 days), and MUD recipients with 19 days (ranging between 11 and 24 days; p = 0.019). Mild acute GvHD (grade I-II) was observed in 13 patients, progressing to chronic GvHD in 5 patients. Three-year OS rates were as follows: MSD group - 67.7%, Haplo group - 42.2%, and MUD group - 44.4% (MSD vs Haplo, p = 0.039). Three-year cumulative treatment-related mortality (TRM) rates were 17.8% for MSD group, 22.9% for Haplo group, and 22.1% for MUD group (pairwise comparisons p > 0.05). Infection-related mortality was reported in eight patients, while relapse rates at 3 years were similar across MSD, Haplo, and MUD groups (p = 0.891). Donor age influenced OS rates, showing better outcomes with donors under 45 years old, and significant differences were found in pairwise comparisons (p = 0.015).

CONCLUSION

Donor type and donor age significantly impacted HSCT outcomes in our analysis, thus emphasizing the importance of rigorous donor selection in risk stratification and suggesting potential benefits for younger donors.

The prognosis and risk factors for patients with complex karyotype myelodysplastic syndrome undergoing allogeneic haematopoietic stem cell transplantation

Allogeneic haematopoietic stem cell transplantation (HCT) is the curative treatment for myelodysplastic syndrome with a complex karyotype (CK-MDS). However, only a few studies have been limited to patients with CK-MDS undergoing allogeneic HCT. This study aimed to identify the risk factors for patients with CK-MDS undergoing allogeneic HCT. We included 691 patients with CK-MDS who received their first allogeneic HCT. The overall survival (OS) was the primary end-point, estimated using the Kaplan-Meier method. Prognostic factors were identified using a Cox proportional hazards model. The 3-year OS was 29.8% (95% confidence interval [CI]: 26.3-33.3). In the multivariable analysis, older age (hazard ratio [HR]: 1.44, 95% CI: 1.11-1.88), male sex (HR: 1.38, 95% CI: 1.11-1.71), poor haematopoietic cell transplant comorbidity index (HR: 1.47, 95% CI: 1.20-1.81), red blood cell transfusion requirement (HR: 1.58, 95% CI: 1.13-2.20), platelet transfusion requirement (HR: 1.85, 95% CI: 1.46-2.35), not-complete remission (HR: 1.55, 95% CI: 1.16-2.06), a high number of karyotype abnormality (HR: 1.63, 95% CI: 1.18-2.25) and monosomal karyotype (HR: 1.49, 95% CI: 1.05-2.12) were significantly associated with OS. Thus, the 3-year OS of allogeneic HCT was 29.8% in patients with CK-MDS, and we identified risk factors associated with poor OS.

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.

Act Together and Act Now to Overcome Gender Disparity in Organ Transplantation

Gender disparity refers to the unequal treatment or a perception of individuals based on their gender and arises from differences in socially constructed gender roles. In the field of transplantation, gender inequality arises at different stages, affecting access to medical care, donation practices, and posttransplant followup care. Gender disparity in transplantation is not limited to any geographic region but is thought to be more prevalent in developing nations. An unusually high number of female donations with relatively fewer female recipients is not only attributable to the low economy but a congregation of medical, social, cultural, and psychological factors. Gender disparities can also be shown in transplant-related professional societies. This review highlights the complexities of spousal donation and vulnerability of women, especially in the developing world. There is a growing need to further modify transplant policies to tackle gender disparities, especially in living related donation. Systematic research in the context of gender-related concerns in transplantation will further aid in understanding the complexities and formulating policies for eliminating gender disparities. Gender disparity is a global problem and not merely limited to transplantation.

Untoward immune effects of modern medication

Immune-related adverse events (irAEs) represent an increasingly concerning challenge in the assessment of biopharmaceutical products. In contrast to historically rare allergic reactions associated with small chemical drugs, contemporary biotherapeutics exhibit a significantly higher morbidity of irAEs, because of their complex structure and comprehensive mechanisms of action. While the immunogenicity of protein-based compounds is associated with the induction of anti-drug antibodies, the pathogenesis of irAEs in advanced biologics, such as cell and gene therapy, remains to be further delineated. In the current study, I present an updated profile regarding the untoward immune effects of medications, covering various material categories systematically, with the underlying mechanisms to inspire risk mitigation in biopharmaceutical development and application.

Acute myeloid leukemia: challenges for diagnosis and treatment in Latin America

OBJECTIVE

to review the current diagnostic and therapeutic landscape of AML in Latin America as a reflection of other low- and middle-income countries and regions of the world. Encompassing both acute promyelocytic and non-promyelocytic disease types.

METHODS

We reviewed the literature and study registries concerning epidemiological features of patients with AML/APL treated in Latin America, as well as evaluated diagnostic and genetic stratification and patient fitness assessment challenges, the importance of early mortality and supportive care capacity, intensive and non-intensive chemotherapy alternatives, consolidation, and maintenance strategies including novel agents and hematopoietic stem cell transplantation.

RESULTS

Although most of the current technologies and treatment options are available in the region, a significant fraction of patients have only limited access to them. In addition, mortality in the first weeks from diagnosis is higher in the region compared to developed countries.

CONCLUSIONS

Disparities in access to technologies, supportive care capacity, and availability of novel agents and HSCT hinder results in our region, reflecting barriers common to other LMICs. Recent developments in the diagnosis and treatment of this disease must be implemented through education, collaborative clinical research, and advocacy to improve outcomes.

Allelic variation of KIR and HLA tunes the cytolytic payload and determines functional hierarchy of NK cell repertoires

The functionality of natural killer (NK) cells is tuned during education and is associated with remodeling of the lysosomal compartment. We hypothesized that genetic variation in killer cell immunoglobulin-like receptor (KIR) and HLA, which is known to influence the functional strength of NK cells, fine-tunes the payload of effector molecules stored in secretory lysosomes. To address this possibility, we performed a high-resolution analysis of KIR and HLA class I genes in 365 blood donors and linked genotypes to granzyme B loading and functional phenotypes. We found that granzyme B levels varied across individuals but were stable over time in each individual and genetically determined by allelic variation in HLA class I genes. A broad mapping of surface receptors and lysosomal effector molecules revealed that DNAM-1 and granzyme B levels served as robust metric of the functional state in NK cells. Variation in granzyme B levels at rest was tightly linked to the lytic hit and downstream killing of major histocompatibility complex-deficient target cells. Together, these data provide insights into how variation in genetically hardwired receptor pairs tunes the releasable granzyme B pool in NK cells, resulting in predictable hierarchies in global NK cell function.

Impact of donor age and relationship on outcomes of peripheral blood haploidentical hematopoietic cell transplantation

Here we describe a retrospective analysis of outcomes in 299 patients who underwent peripheral blood haplo-HCT with PTCy from July 2009 through May 2021 and their association with donor characteristics. Patients had mostly acute leukemias and high or very high DRI. Multivariate analyses were conducted examining OS, NRM, relapse, cytokine release syndrome, acute and chronic GVHD. Donor characteristics included age, sex, relationship, ABO status, CMV status, and HLA match grade. Our analysis revealed increasing donor age was associated with higher NRM (compared to age <30; age 30-44 HR, 1.65; P = 0.110, age >44 HR, 1.80; P = 0.056) but lower relapse risk (compared to age <30; age 30-44 HR, 0.61; P = 0.034, age > 44 HR, 0.71; P = 0.132). There were no differences in CRS, aGVHD or cGVHD. We found no difference in outcomes based on the donor-recipient relationship. No differences were found based on HLA match grade or DRB1 match status. Increasing donor age was associated with lower relapse risk but higher NRM, resulting in no difference in OS based on donor age. Other donor factors including relationship (parent/sibling/child/ maternal), CMV status, donor sex, HLA match grade, and DRB1 status were not associated with outcomes.

The delicate balance of graft versus leukemia and graft versus host disease after allogeneic hematopoietic stem cell transplantation

INTRODUCTION

The curative basis of allogeneic hematopoietic stem cell transplantation (HSCT) relies in part upon the graft versus leukemia (GvL) effect, whereby donor immune cells recognize and eliminate recipient malignant cells. However, alloreactivity of donor cells against recipient tissues may also be deleterious. Chronic graft versus host disease (cGvHD) is an immunologic phenomenon wherein alloreactive donor T cells aberrantly react against host tissues, leading to damaging inflammatory symptoms.

AREAS COVERED

Here, we discuss biological insights into GvL and cGvHD and strategies to balance the prevention of GvHD with maintenance of GvL in modern HSCT.

EXPERT OPINION/COMMENTARY

Relapse remains the leading cause of mortality after HSCT with rates as high as 40% for some diseases. GvHD is a major cause of morbidity after HSCT, occurring in up to half of patients and responsible for 15-20% of deaths after HSCT. Intriguingly, the development of chronic GvHD may be linked to lower relapse rates after HSCT, suggesting that GvL and GvHD may be complementary sides of the immunologic foundation of HSCT. The ability to fine tune the balance of GvL and GvHD will lead to improvements in survival, relapse rates, and quality of life for patients undergoing HSCT.

Case report: Curing a rare, unstable hemoglobin variant Hb Bristol-Alesha using haploidentical hematopoietic stem cell transplantation

Unstable hemoglobinopathies are a rare, heterogeneous group of diseases that disrupt the stability of hemoglobin (Hb), leading to chronic hemolysis and anemia. Patients with severe phenotypes often require regular blood transfusions and iron chelation therapy. Although rare, studies have reported that hematopoietic stem cell transplantation (HSCT) seems to be an available curative approach in transfusion-dependent patients with unstable hemoglobinopathies. Here, we describe successful haploidentical HSCT for the treatment of an unstable Hb variant, Hb Bristol-Alesha, in a 6-year-old boy with severe anemia since early childhood. Two years after transplantation, he had a nearly normal hemoglobin level without evidence of hemolysis. DNA analysis showed complete chimerism of the donor cell origin, confirming full engraftment with normal erythropoiesis.

Efficacy and safety of allogeneic hematopoietic cell transplantation in acute myeloid leukemia patients aged > 65 years with unfavorable cytogenetics

Unrelated donor bone marrow transplantation (UR-BMT), unrelated donor cord blood stem cell transplantation (UR-CBT), and haploidentical peripheral blood stem cell transplantation (Haplo-PBSCT) are the main alternative stem cell sources for allogeneic hematopoietic cell transplantation (HCT) in Japan. The present study aimed to identify factors associated with the outcomes of UR-BMT, UR-CBT, and Haplo-PBSCT in older patients with acute myeloid leukemia (AML) and intermediate- or poor-risk cytogenetics to improve the clinical efficacy and safety of allogeneic HCT. We retrospectively analyzed data for 448 AML patients aged > 65 years who received UR-BMT (n = 102), UR-CBT (n = 250), or Haplo-PBSCT (n = 96) between 2014 and 2020. Overall survival (OS) in the UR-BMT group was superior (P = 0.033) to that in the other groups. However, all patients without complete remission (non-CR) who had Karnofsky performance status (KPS) < 80 at HCT and poor-risk cytogenetics died within 1 year after HCT. Multivariate Cox regression analysis identified KPS <80 at HCT and poor-risk cytogenetics as independent predictors of worse OS in non-CR patients. KPS < 80 may be an alternative indicator for non-CR AML patients with poor-risk cytogenetics during the selection of HCT, alternative treatments, or best supportive therapy, and the optimal KPS is important for the success of HCT.

Hematopoietic Stem Cell Transplantation in Thalassemia

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only consolidated, potentially curative treatment for patients with transfusion-dependent thalassemia major. In the past few decades, several new approaches have reduced the toxicity of conditioning regimens and decreased the incidence of graft-versus-host disease, improving patients' outcomes and quality of life. In addition, the progressive availability of alternative stem cell sources from unrelated or haploidentical donors or umbilical cord blood has made HSCT a feasible option for an increasing number of subjects lacking an human leukocyte antigen (HLA)-identical sibling. This review provides an overview of allogeneic hematopoietic stem cell transplantation in thalassemia, reassesses current clinical results, and discusses future perspectives.

HLA Factors versus Non-HLA Factors for Haploidentical Donor Selection

When multiple haploidentical donors are available for transplantation, those of younger generations are generally selected over those of older generations. However, it is unclear who is the optimal donor when selecting candidates from within a generation, such as father versus mother, son versus daughter, or brother versus sister. Although traditionally male donors are favored over female donors, particularly for male recipients, and significant associations of individual HLA mis(matches) on outcomes are being increasingly recognized, the hierarchy of factors for donor selection is indeterminate. To assess whether HLA factors take precedence over non-HLA factors and to isolate the influence of specific characteristics on outcomes, we analyzed 412 patients stratified by donor relationship: child donor (son [n = 202] versus daughter [n = 96]), parent (father [n = 28] versus mother [n = 29]), and sibling (noninherited maternal [NIMA; n = 29] versus paternal [NIPA; n = 28] mismatched). Among siblings, NIMA mismatch was associated with a lower risk of acute graft-versus-host disease (aGVHD); B-leader mismatch was associated with high nonrelapse mortality (NRM), poor progression-free survival, and a trend toward poor overall survival (OS), whereas A-mismatch was associated with lower aGVHD. Among parent donors, the relationship did not impact any outcome; B-leader mismatch was associated with higher NRM and a trend toward poor OS, whereas A-mismatch was associated with lower NRM and improved progression-free survival and OS. Among child donors, no individual HLA mismatch was predictive of any outcome, and daughter donors were not associated with any adverse outcomes in multivariate analyses. Our data suggest that certain HLA factors may be more significant in some cases and should be given priority over simply selecting a donor based on relationship/sex.

Peripheral blood persistence and expansion of transferred non-genetically modified Natural Killer cells might not be necessary for clinical activity

Natural killer (NK) cells are innate lymphocytes that react without previous exposition to virus infected or malignant cells and stimulate adaptive immune response to build a long-lasting immunity against it. To that end, tissue resident NK cells are predominantly regulatory as opposed to cytotoxic. In the hematopoietic stem cell transplant (HSCT) setting, which curative potential relies on the graft versus leukemia effect, NK cells are known to play a significant role. This knowledge has paved the way to the active investigation on its anti-tumor effect outside the stem cell transplant scenario. Based on the relevant literature on the adoptive transfer of non-genetically modified NK cells for the treatment of relapsed/refractory acute leukemia and on our own experience, we discuss the role of donor cell peripheral blood persistence and expansion and its lack of correlation with anti-leukemia activity.

Impact of Lymphocyte Subsets of Grafts on the Outcome of Haploidentical Peripheral Blood Stem Cell Transplantation

The contribution of lymphocyte subset composition of the graft on the outcomes following haploidentical peripheral blood stem cell transplantation (haploPBSCT) is not fully elucidated. We retrospectively analyzed 314 patients with hematological malignancies who underwent haploPBSCT from 2016 to 2020 in our center. We obtained a cutoff value of CD3+ T cell dose (2.96 × 10⁸/kg) that separated the risk of II-IV acute graft-versus-host disease (aGvHD) and divided patients into the low CD3+ T cell dose group (CD3+ low) and the high CD3+ T cell dose (CD3+ high) group. Significantly higher incidences of I-IV aGvHD, II-IV aGvHD, and III-IV aGvHD were identified in the CD3+ high group (50.8%, 19.8%, and 8.1% in the high group, 23.1%, 6.0%, and 0.9% in the low group, P < 0.0001, P = 0.002, and P = 0.02, respectively). We found that CD4+ T cell and its naïve and memory subpopulations of grafts had a significant impact on aGvHD (P = 0.005, P = 0.018, and P = 0.044). Besides, we found an inferior reconstitution of natural killer (NK) cells in the CD3+ high group than in the low group within the first-year posttransplant (239 cells/μL vs 338 cells/μL, P = 0.0003). No differences in engraftment, chronic GvHD (cGvHD), relapse rate, transplant-related mortality (TRM), and overall survival (OS) were identified between the two groups. In conclusion, our study found that a high CD3+ T cell dose led to a high risk of aGvHD and inferior reconstitution of NK cells in the haploPBSCT setting. In the future, carefully manipulating the composition of lymphocyte subsets of grafts might reduce the risk of aGvHD and improve the transplant outcome.

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.

Outcomes of patients who underwent treatment for anti-HLA donor-specific antibodies before receiving a haploidentical hematopoietic cell transplant

Pediatric and adolescent and young adult (AYA) patients who receive many blood product transfusions, such as individuals with sickle cell disease (SCD), severe aplastic anemia (SAA) or indolent hematologic malignancies, are at high risk for developing donor-specific antibodies (DSA). DSAs with mean fluorescence intensity (MFI) greater than 5000 have been associated with significant graft failure, but lower MFI values between 2000 and 5000 may result in poor graft function after hematopoietic cell transplant (HCT). Desensitization strategies have been developed to reduce the DSA burden in HCT recipients before graft infusion, but the experience with these strategies in the pediatric and AYA populations is not well described in the literature. Here, we describe our experience with successful desensitization by using a combination of treatment strategies in five pediatric and AYA patients, including a novel use of daratumumab in a young adult patient who had refractory DSAs and had suffered serious side effects from conventional desensitization strategies. The presence of elevated DSAs in pediatric and AYA recipients of a human leukocyte antigen (HLA)-mismatched haploidentical HCT can be overcome by a multipronged treatment strategy.

Characteristics of Graft-Versus-Host Disease (GvHD) After Post-Transplantation Cyclophosphamide Versus Conventional GvHD Prophylaxis

Post-transplantation cyclophosphamide (PTCy) has been shown to effectively control graft-versus-host disease (GvHD) in haploidentical (Haplo) transplantations. In this retrospective registry study, we compared GvHD organ distribution, severity, and outcomes in patients with GvHD occurring after Haplo transplantation with PTCy GvHD prophylaxis (Haplo/PTCy) versus HLA-matched unrelated donor transplantation with conventional prophylaxis (MUD/conventional). We evaluated 2 cohorts: patients with grade 2 to 4 acute GvHD (aGvHD) including 264 and 1163 recipients of Haplo and MUD transplants; and patients with any chronic GvHD (cGvHD) including 206 and 1018 recipients of Haplo and MUD transplants, respectively. In comparison with MUD/conventional transplantation ± antithymocyte globulin (ATG), grade 3-4 aGvHD (28% versus 39%, P = .001), stage 3-4 lower gastrointestinal (GI) tract aGvHD (14% versus 21%, P = .01), and chronic GI GvHD (21% versus 31%, P = .006) were less common after Haplo/PTCy transplantation. In patients with grade 2-4 aGvHD, cGvHD rate after Haplo/PTCY was also lower (hazard ratio [HR] = .4, P < .001) in comparison with MUD/conventional transplantation without ATG in the nonmyeloablative conditioning setting. Irrespective of the use of ATG, non-relapse mortality rate was lower (HR = .6, P = .01) after Haplo/PTCy transplantation, except for transplants that were from a female donor into a male recipient. In patients with cGvHD, irrespective of ATG use, Haplo/PTCy transplantation had lower non-relapse mortality rates (HR = .6, P = .04). Mortality rate was higher (HR = 1.6, P = .03) during, but not after (HR = .9, P = .6) the first 6 months after cGvHD diagnosis. Our results suggest that PTCy-based GvHD prophylaxis mitigates the development of GI GvHD and may translate into lower GvHD-related non-relapse mortality rate.

Development of protective agents against ovarian injury caused by chemotherapeutic drugs

BACKGROUND

Chemotherapy is one of the causes of ovarian injury and infertility. Although assisted reproductive technology helps young female patients with cancer become pregnant, preventing chemotherapy-induced ovarian injury will often possess even more significant benefits.

OBJECTIVE

We aimed at demonstrating the hazardous effects and mechanisms of ovarian injury by chemotherapeutic agents, as well as demonstrating agents that protect the ovary from chemotherapy-induced injury.

RESULTS

Chemotherapeutic agents cause death or accelerate activation of follicles and damage to the blood vessels in the ovary, resulting in inflammation. These often require drug development to protect the ovaries from injury.

CONCLUSIONS

Our findings provide a basis for the development of drugs to protect the ovaries from injury. Although there are many preclinical studies on potential protective drugs, there is still an urgent need for a large number of clinical experiments to verify their potential use.

Predicting the risk of acute kidney injury after hematopoietic stem cell transplantation: development of a new predictive nomogram

The purpose was to predict the risk of acute kidney injury (AKI) within 100 days after hematopoietic stem cell transplantation (HSCT) in patients with hematologic disease by using a new predictive nomogram. Collect clinical data of patients with hematologic disease undergoing HSCT in our hospital from August 2012 to March 2018. Parameters with non-zero coefficients were selected by the Least Absolute Selection Operator (LASSO). Then these parameters were selected to build a new predictive nomogram model. Receiver operating characteristic (ROC) curve, calibration curve, C-index, and decision curve analysis (DCA) were used for the validation of the evaluation model. Finally, the nomogram was further evaluated by internal verification. According to 2012 Kidney Disease Improving Global Guidelines (KDIGO) diagnostic criteria, among 144 patients, the occurrence of AKI within 100 days after HSCT The rate was 29.2% (42/144). The C-index of the nomogram was 0.842. The C-value calculated by the internal verification was 0.809. The AUC was 0.842, and The DCA range of the predicted nomogram was from 0.01 to 0.71. This article established a high-precision nomogram for the first time for predicting the risk of AKI within 100 days after HSCT in patients with hematologic diseases. The nomogram had good clinical validity and reliability. For clinicians, it was very important to prevent AKI after HSCT.

Impact of second-degree related donor on the outcomes of T cell-replete haploidentical transplantation with post-transplant cyclophosphamide

Donor selection may contribute to improve clinical outcomes of T cell-replete haploidentical stem cell transplantation (Haplo-SCT) with post-transplant cyclophosphamide (PT-Cy). Impact of second-degree related donor (SRD) was not fully elucidated in this platform. We retrospectively compared the outcome of patients receiving Haplo-SCT either from a SRD (n = 31) or a first-degree related donor (FRD, n = 957). Median time to neutrophil and platelet recovery did not differ between a SRD and a FRD transplant (p = 0.599 and 0.587). Cumulative incidence of grade II-IV acute graft-versus host disease (GVHD) and moderate-severe chronic GVHD was 13% and 19% after SRD vs 24% (p = 0.126) and 13% (p = 0.395) after FRD transplant. One-year cumulative incidence of non-relapse mortality (NRM) was 19% for SRD and 20% for FRD (p = 0.435) cohort. The 3-year probability of overall survival (OS) and progression-free survival (PFS) was 42% vs 55% (p = 0.273) and 49% vs 35% (p = 0.280) after SRD and FRD transplant, respectively. After propensity score adjustment or matched pair analysis, the outcome of patients receiving Haplo-SCT from a SRD or a FRD did not differ in terms of NRM, OS, PFS, acute and chronic GVHD. Our results suggest that a SRD is a viable option for Haplo-SCT with PT-Cy when a FRD is not available.

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.

Sphingolipid metabolism in T cell responses after allogeneic hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective immunotherapy against hematopoietic malignancies. The infused donor lymphocytes attack malignant cells and normal tissues, termed a graft-verse-leukemia (GVL) effect and graft-verse-host (GVH) response or disease (GVHD), respectively. Although engineering techniques toward donor graft selection have made HCT more specific and effective, primary tumor relapse and GVHD are still major concerns post allo-HCT. High-dose systemic steroids remain to be the first line of GVHD treatment, which may lead to steroid-refractory GVHD with a dismal outcome. Therefore, identifying novel therapeutic strategies that prevent GVHD while preserving GVL activity is highly warranted. Sphingolipid metabolism and metabolites play pivotal roles in regulating T-cell homeostasis and biological functions. In this review, we summarized the recent research progress in this evolving field of sphingolipids with a focus on alloreactive T-cell responses in the context of allo-HCT. We discussed how sphingolipid metabolism regulates T-cell mediated GVH and GVL responses in allo-HCT and presented the rationale and means to target sphingolipid metabolism for the control of GVHD and leukemia relapse.

Donor selection based on NK alloreactivity for patients with hematological malignancies

Natural killer (NK) cells are an important defender against infections and tumors. Their function is regulated by the balance of inhibitory and activating receptors. Among all inhibitory NK receptors: killer immunoglobulin-like receptors (KIR) and CD94/NKG2A recognize human leukocyte antigen (HLA) Class I molecules, allowing NK cells to be 'licensed' to avoid autoreactivity, but be fully functional at the same time. Licensed NK cells can target malignant cells with altered or downregulated/missing 'self' antigens. NK cell attacking malignant cells is one of the mechanisms of graft-versus-leukemia (GVL) effect. Numerous studies have demonstrated that NK cells improve hematopoietic stem cell transplantation (HCT) survival by reducing relapse mortality through GVL effect. Therapeutic strategies, such as adoptive alloreactive NK cell transfer, CAR-NK cells, antibodies against NKG2A and KIR2DL1-3, have been utilized to treat hematological malignancies in HCT. In this review, NK cell functions, NK cell receptors and ligands, as well as common alloreactive NK donor selection algorithms for patients with hematological malignancies in the setting of HCT are discussed. The goal of this review is to provide insights on the controversial results and provide better understanding and resources on how to perform alloreactive donor NK cell selection in HCT.

Myeloablative Conditioning Regimen in Haploidentical Stem Cell Transplantation With Posttransplant Cyclophosphamide in Children With High-risk Hematologic Malignancies

Limited information is available on outcomes of haploidentical stem cell transplantation (haploSCT) with posttransplant cyclophosphamide using myeloablative conditioning regimens in children and adolescents. We report the results of a single-institution retrospective study of myeloablative haploSCT in 36 children and adolescents (median age, 8 y; range, 9 mo to 22 y) with high-risk hematologic malignancies. Donor engraftment occurred in 31 of 33 evaluable patients (94%). Recovery of neutrophils and platelets occurred at a median of 15 and 20 days. Cumulative incidence of acute graft-versus-host-disease (GVHD) grades II to IV and grades III to IV at 100 days was 36±8.7% and 10±5.4% and of chronic GVHD at 1 year was 55±9.2%, with 31±8.6% moderate to severe. Nonrelapse mortality was 16±6.1% and 22±6.9% at 100 days and 1 year. The cumulative incidence of relapse at 4 years was 32±8.8%. With a median follow-up of 57 months (range, 8 to 89 mo), the overall survival and event-free survival at 4 years was 55.6±8.7% and 44.8±8.5%. Myeloablative conditioning T-replete haploSCT with posttransplant cyclophosphamide is a viable alternative to matched unrelated transplantation for children and adolescents with high-risk hematologic malignancies. The high rates of nonrelapse mortality and chronic GVHD is a concern and deserves careful consideration.

Updated Trends in Hematopoietic Cell Transplantation in the United States with an Additional Focus on Adolescent and Young Adult Transplantation Activity and Outcomes

Hematopoietic cell transplantation (HCT) has been successfully used to treat many malignant and nonmalignant conditions. As supportive care, donor selection, and treatment modalities evolve, documenting HCT trends and outcomes is critical. This report from the Center for International Blood and Marrow Transplant Research (CIBMTR) provides an update on current transplantation activity and survival rates in the United States. Additional data on the use and outcomes of HCT in the adolescent and young adult (AYA) population are included. AYA patients more frequently receive peripheral blood stem cell grafts than pediatric patients, which may reflect differences in practice in pediatric versus adult treatment centers. The proportions of donor types also differ those in adult and pediatric populations. Outcomes for patients in the AYA age range are similar to those of pediatric patients for acute myelogenous leukemia but worse for acute lymphoblastic leukemia. Outcomes for both leukemias are better in AYA patients compared with older adults. Comparing the time periods 2000 to 2009 and 2010 to 2019 revealed significant improvement in overall survival across the age spectrum, but the greatest improvement in the AYA age group.

Impact of Donor-to-Recipient ABO Mismatch on Outcomes of Antithymocyte Globulin-Based Peripheral Blood Stem Cell-Derived Myeloablative Conditioning Haploidentical Stem Cell Transplantation

ABO incompatibility is common in hematopoietic stem cell transplantation (HSCT); however, the impact of donor-recipient ABO compatibility on transplantation outcomes in different HSCT settings is controversial. Moreover, haploidentical stem cell transplantation (haplo-SCT) with peripheral blood stem cell (PBSC)-derived grafts has not been well investigated. The present study aimed to investigate the impact of ABO incompatibility on post-transplantation outcomes, engraftment kinetics, blood product requirements, transfusion independence, and the incidence of poor graft function (PGF) in antithymocyte globulin (ATG)-based haplo-SCT with PBSC grafts during long-term follow-up. We prospectively evaluated 510 patients with hematologic malignancies who underwent haplo-SCT after myeloablative conditioning (MAC). The primary endpoint was overall survival (OS), and secondary endpoints were nonrelapse mortality (NRM), graft-versus-host disease (GVHD), relapse, neutrophil and platelet engraftment, blood transfusion requirements, transfusion independence, and the incidence of PGF. There was no significant association between ABO matching and OS, disease-free survival (DFS), relapse, NRM, grade II-IV acute GVHD, grade III-IV acute GVHD, and moderate and severe chronic GVHD. There were also no significant differences in neutrophil and platelet engraftment, blood transfusion independence, and transfusion requirements at 30, 60, 90, 180, and 365 days post-transplantation among patients with ABO matching and those with minor, major, or bidirectional ABO incompatibility. Donor-recipient ABO matching did not differ significantly according to graft function (good versus poor). ABO incompatibility status has no major impact on patient outcomes in patients with hematologic malignancies undergoing ATG-based MAC haplo-SCT with PBSC-derived grafts.

Risk factors for adverse outcomes following haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide: a two-center analysis

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative therapy for several malignant hematologic diseases and alternative donors, including haploidentical, play a significant role in HCT. Despite the increasing use of haplo-HCT with PTCy, some questions remain open. The objective of the present study was to investigate risk factors for adverse outcomes after haplo-HCT with PTCy. This is a retrospective study conducted at two Brazilian centers. A total of 103 patients with hematologic malignancies who underwent first allogeneic, haploidentical HCT with PTCy were included. Risk factors for death were age at transplant (HR = 1.03 for each year; p = 0.002) and high/very high disease risk index (DRI; HR = 2.77; p = 0.0007) and mother as the donor compared with other donors (HR = 3.53; p = 0.005). In multivariate analysis, PFS was significantly poorer for older patients (HR = 1.02; p = 0.006), high/very high DRI (HR = 2.39; p = 0.003), and mother as the donor compared with other donors (HR = 3.18; p = 0.006). Relapse rate was higher for high/very high DRI (HR = 4.01; p = 0.002) and mother as the donor compared with other donors (HR = 2.52; p = 0.05). NRM was higher for older patients (HR = 1.03 for each year; p = 0.03). Tacrolimus was a protective factor for grades II-IV aGVHD (HR = 0.46; p = 0.04) compared with cyclosporine. Peripheral blood (PBSC) was a risk factor for cGVHD (HR = 3.48; p = 0.006), while tacrolimus was protective (HR = 0.30; p = 0.009). Mother as the donor compared with other donors was also a risk factor for poorer OS, PFS, and relapse, suggesting that this combination should be avoided. Tacrolimus was protective for both grades II-IV aGVHD and cGVHD, suggesting that tacrolimus may be more effective than cyclosporine in preventing GVHD. PBSC was a risk factor for cGVHD without any impact on relapse. Prospective studies comparing tacrolimus with cyclosporine are awaited.

Unresolved issues in allogeneic hematopoietic cell transplantation for non-malignant diseases

Allogeneic hematopoietic cell transplantation (HCT) can be curative for a variety of non-malignant diseases (NMDs) as well as hematological malignancies. However, there are several fundamental differences between HCT for NMDs and hematological malignancies, which may necessitate the use of alternative HCT strategies. For example, these diseases differ in the intensity of conditioning regimen sufficient to improve disease. In addition, patients with NMDs are at higher risk of graft failure or mixed chimerism following HCT, and gain no or little survival benefit from graft-versus-host disease. Because more than 80% of patients with NMDs become long-term survivors, greater attention has been paid to late adverse effects and decreased of quality of life after HCT. This review addresses several unresolved issues in allogeneic HCT for patients with NMDs, such as (1) stem cell source, (2) conditioning regimen, (3) use of serotherapy or low-dose irradiation, and (4) therapeutic intervention for mixed chimerism. Resolving these issues may improve transplant outcomes in patients with NMDs.

HAPLOIDENTICAL STEM CELL TRANSPLANTATION AFTER TCR αβ+AND CD19+ CELLS DEPLETION IN CHILDREN WITH CONGENITAL NON-MALIGNANT DISEASE

BACKGROUND

. Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) represents a valuable alternative for children with non-malignant disease and ex-vivo negative selection of TCR αβ⁺-cells is an emerging graft manipulation option that carries several potential advantages in terms of reduced risk of Graft versus Host Disease (GvHD) and improved immune reconstitution.

METHODS

. We reported all consecutive patients with a diagnosis of non-malignant disease who received a TCR-αβ⁺ and CD19⁺depleted haplo-HSCT at "IRCCS Istituto Giannina Gaslini" from 2013 to 2019; the conditioning regimen was myeloablative or non-myeloablative, depending on underlying disease; all patients received anti-thymocyte globulin and rituximab. No post-transplant GvHD prophylaxis was given in presence of a TCR-αβ⁺ cell-dose in the graft lower than the threshold of 1 × 10⁵/kg of the recipient's weight.

RESULTS

. Among 20 HSCTs, engraftment occurred in 17 (85%) after a median of 14 and 12 days from graft infusion for neutrophils and platelets respectively. Primary graft failure was diagnosed in 3 (15%) patients, two (10%) experienced secondary rejection; all of these underwent a second HSCT. The cumulative incidence of a-GvHD and c-GvHD was 15% (2 grade 1, 1 grade 4) at 90 days and 5% (1 grade 1) at 7 months, respectively. Cytomegalovirus reactivation requiring pre-emptive treatment was observed in 9 patients (45%). One patient developed a JC virus-related progressive multifocal leukoencephalopathy, successfully managed with donor-derived virus-specific T-cell infusions. A complete immunological recovery was reached in most patients within 6 months. After a median follow-up of 4 years, 18 patients are alive, with a cumulative survival probability of 90%.

CONCLUSION

. Haplo-HSCT after ex-vivo TCR-αβ⁺/CD19⁺ negative selection may be considered a good option for children with non-malignant diseases since it ensures a high engraftment rate with an acceptable risk of graft failure, very low incidence of significant GvHD, and good immune reconstitution with low frequency of severe virus-related disease. However, the control of viral infection/reactivation should be kept high in order to promptly provide pre-emptive treatments and approaches of antiviral adoptive immunotherapy.

Haploidentical hematopoietic stem cell transplantation in pediatric and adolescent patients: A study of the Spanish hematopoietic stem cell transplantation group (GETH)

INTRODUCTION

The main advantages of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) are the immediate availability of donors, the possibility of developing cell therapy approaches with different novel transplant platforms, and the procedure's cost savings.

METHODOLOGY

We retrospectively analyzed the pediatric haplo-HSCT activity of the Spanish hematopoietic stem-cell transplantation group (GETH) between 1999 and 2016, aiming to study clinical characteristics and outcomes by describing patient groups with non-malignant disease (NMD) or malignant disease (MD) and the impact of 2 different periods (1999-2009 and 2010-2016) on long-term outcomes.

RESULTS

Twelve centers performed 232 haplo-HSCTs in 227 children, representing 10% of all pediatric allogeneic HSCT activity in Spain from 1999 to 2016, with a notable increase since 2013. Most haplo-HSCTs (86.7%) were performed in patients with MD; 95% received peripheral blood stem cells from donors, and 78.9% received ex vivo T-cell depleted grafts. Non-manipulated grafts using post-transplantation cyclophosphamide have been incorporated since 2012. We observed a higher percentage of graft failure in NMD versus MD (32% vs. 15.6%; p=0.029). Relapse and transplant-related mortality were the procedure's main limitations in MD and NMD, respectively. Five-year overall survival was 48.5% (SE 3.9), with no statistically significant difference when comparing the MD and NMD cohorts. Patients who received previously a HSCT the overall survival was significantly decreased. We observed no survival improvement over time.

CONCLUSIONS

Although haplo-HSCT is an increasingly employed treatment option, our patients' results need improvement. We need to develop reference centers, especially for NMD whose rarity makes it difficult to gain experience.

KIR in Allogeneic Hematopoietic Stem Cell Transplantation: Need for a Unified Paradigm for Donor Selection

Allogeneic hematopoietic stem cell transplantation (aHSCT) is a lifesaving therapy for hematological malignancies. For years, a fully matched HLA donor was a requisite for the procedure. However, new immunosuppressive strategies have enabled the recruitment of viable alternative donors, particularly haploidentical donors. Over 95% of patients have at least two potential haploidentical donors available to them. To identify the best haploidentical donor, the assessment of new immunogenetic criteria could help. To this end, the clinical benefit of KIR genotyping in aHSCT has been widely studied but remains contentious. This review aims to evaluate the importance of KIR-driven NK cell alloreactivity in the context of aHSCT and explain potential reasons for the discrepancies in the literature. Here, through a non-systematic review, we highlight how the studies in this field and their respective predictive models or scoring strategies could be conceptually opposed, explaining why the role of NK cells remains unclear in aHCST outcomes. We evaluate the limitations of each published prediction model and describe how every scoring strategy to date only partly delivers the requirements for optimally effective NK cells in aHSCT. Finally, we propose approaches toward finding the optimal use of KIR genotyping in aHSCT for a unified criterion for donor selection.

"Giving the gift of life twice": Understanding the lived experiences of parent donors and nondonors in pediatric haploidentical hematopoietic cell transplantation

BACKGROUND

The use of parental donors in pediatric haploidentical hematopoietic cell transplantation is increasing, but research on the psychosocial impact of parental donation is currently limited.

OBJECTIVES

As part of a larger study, we conducted a retrospective, qualitative analysis to explore parental perceptions of the donation process and the impact of being a donor (or nondonor) on parents' adjustment and coping with their child's transplant experience.

METHODS

Parents/caregivers of children who underwent transplantation with a parental donor or a matched unrelated donor (N = 136) participated in interviews and completed an open-ended questionnaire.

RESULTS

Six themes were identified in the data: level of understanding and satisfaction; perception of choice; preparation for donation; perceptions of donation and infusion; benefit finding; and psychological impact of transplantation. Most parents were satisfied with the information they received and reported a good understanding of transplantation and donation procedures. Parents were divided on perspectives of choice, but their responses reflect that the necessity of saving their child's life does not allow for choice. They described considerable effort to prepare for transplantation, physically, emotionally, and logistically. Parents acknowledged the psychological impact while identifying positive outcomes that resulted from their child's transplant journey.

CONCLUSIONS

Results highlight the unique experiences of parental donors and nondonors from the anticipation phase to the completion of their child's transplant. Additionally, findings inform supportive care guidance by highlighting the need to assess parental donors' emotional functioning, provide support post donation, and conduct bereavement follow-up.

The impact of HLA donor-specific antibodies on engraftment and the evolving desensitization strategies

The majority of contemporary allogeneic hematopoietic stem cell transplantation (HCT) procedures utilize partially HLA-mismatched stem cell grafts. Donor-specific anti-HLA antibodies (DSA) are associated with primary graft failure independent of the graft source, conditioning intensity and other patient and donor factors. Here we provide an update on testing and monitoring of DSA, review the impact of DSA on stem cell engraftment, and present promising desensitization modalities. Ultimately, we attempt to provide practical recommendations for DSA screening and mitigation strategies.

The impact of donor type on resource utilization and costs in allogeneic hematopoietic stem cell transplantation in the Netherlands

Background

Allogeneic haematopoietic stem cell transplantation (HSCT) is increasingly used, but this treatment is complex and costly. As clinical outcomes of HSCT with matched unrelated donor (MUD) and haploidentical donors are similar, costs could influence donor choice.

Method

We retrospectively compared resource utilisation and costs of HSCT using the three different donor types (matched related donor (MRD) (n = 32), haploidentical related (n = 30) and MUD (n = 60)) within the first year after transplantation. Costs were analysed through a bottom‐up method. Non‐parametric bootstrapping was applied to test for statistical differences in costs. Subgroup analyses were performed to identify predictors for costs.

Results

Cost pre‐transplant for search and acquisition of the graft were significantly higher in MUD HSCT (€35 222) versus MRD and haploidentical HSCT (€15 356 and €16 097 respectively). The costs of haploidentical HSCT were the highest in the transplant phase. Main cost factors were inpatient days and medication. Overall, the costs for haploidentical and MUD HSCT were similar (€115 724 for MUD, €113 312 for haploidentical).

Conclusion

Our study suggests no difference in total transplantation costs between allogeneic HSCT using a MUD or a haploidentical donor. Since clinical outcomes seem similar as well, the choice of donor type might be based on availability, speed and logistics.

Effect of donor characteristics on T cell-replete haploidentical stem cell transplantation over the last 10 years at a single institution

One of the most complex issues with haploidentical stem cell transplantation (haplo-SCT) is donor selection, given that multiple haploidentical donors are often available for a given recipient. To develop evidence-based guidance for donor selection in the setting of anti-thymocyte globulin-based haplo-SCT, we performed a prospective cohort study of 512 patients with haematological malignancies who had haplo-SCT to determine which donor variables were most important in favouring transplant outcomes. Increasing donor age was associated with poorer overall survival (OS) [hazard ratio (HR) 1·08, P = 0·044]. Female donors to male recipients was significantly associated with higher non-relapse mortality (NRM; HR 2·05, P = 0·006). Furthermore, increasing donor age had a higher risk of Grades 3-4 acute graft-versus-host disease (aGVHD; HR 1·17, P = 0·005), female donors to male recipients was associated with a higher risk of Grades 2-4 aGVHD (HR 1·50, P = 0·022). Sibling donors had superior OS, disease-free survival, and NRM than parental donors in patients aged <35 years. However, sibling donors had higher NRM than offspring donors in patients aged ≥35 years. A younger donor, usually a young sibling in younger recipients (aged <35 years) or a young offspring in older patients (aged ≥35 years) and avoiding female donors to male recipients should be preferred when multiple haploidentical donors are available.

Clinical Outcomes of Unrelated Umbilical Cord Blood Graft vs. Haploidentical Donor Transplantation: Critical Issues for an Adequate Comparison

Unrelated umbilical cord blood (UCB) and haploidentical grafts have been used for allogeneic hematopoietic stem and progenitor cell (HSPC) transplantation in patients without a related or non-related human leukocyte antigen (HLA)-matched donor. The less stringent HLA-matching requirement in both sources raises an important possibility for patients in need of urgent transplantation to treat any hematological disease. Selection of the best alternative donor is a difficult task that will depend on donor criteria, center experience, patient disease conditions, and risk, among others. Most comparisons available in scientific publications between both graft sources are obtained from retrospective analysis in wide time windows and a heterogeneous number of patients, types of disease, disease stages, previous treatments, graft source, conditioning regimen, graft vs. host disease (GVHD) approach, and evaluable endpoints. There is also an evident impact of the economic traits since low-income countries must consider less expensive treatments to satisfy the needs of the patients in the most effective possible path. Therefore, haploidentical transplantation could be an appealing option, even though it has not been completely established if any chronic treatment derived from the procedure could become a higher cost. In Colombia, there is a huge experience in UCB transplantation especially in units of pediatric transplantation where benign indications are more common than in adults. Due to the availability of a public UCB bank and HLA high-resolution typing in Colombia, there is a wider inventory of cord blood donors. Unfortunately, we do not have an unrelated bone marrow donor registry, so UCB is an important source along with haploidentical transplantation to consider in decision-making. This minireview focuses on comparing the main issues associated with the use of both HSCP sources and provides tools for physicians who face the difficult decision between these alternative donor sources.