Use of haploidentical stem cell transplantation continues to increase: the 2015 European Society for Blood and Marrow Transplant activity survey report

Initiation of Haploidentical Stem Cell Transplantation With Post-Transplant Cyclophosphamide in Children: A Low-Middle-Income Country Institutional Experience

BACKGROUND

Haploidentical hematopoietic stem cell transplant (HSCT) is a curative treatment especially for countries where bone marrow registries are nonexistent. We present our experience with haploidentical HSCT in pediatric patients.

METHODS

Retrospective data collected and analyzed for patients ≤18 years, from January 2017 to December 2022.

RESULTS

The cohort consisted of 20 patients with median age at transplant of 61.5 (IQR: 124) months. Fourteen (70%) were malignant and 6 (30%) were benign diseases. Donors were father in majority (9/20; 45%). Stem cell source was peripheral blood 8, marrow 8, and combined 4. c-specific antibodies were positive in 6 (30%). Median CD34 cell dose infused: 9.35 × 106/kg. Median engraftment time: 15 (IQR: 17) days. Acute and chronic graft-versus-host disease (GVHD) occurred in 12/20 (60%) and 5/20 (25%), respectively. Complications included infection/sepsis (14/20; 70%), cytomegalovirus reactivation (14/20; 70%), sinusoidal obstruction syndrome (1/20; 5%), primary graft failure (PGF) (6/20; 30%), and secondary graft failure (4/20; 20%). PGF was more common in benign conditions (p = 0.003) and less prevalent in cases with aGVHD (p = 0.007). aGVHD was more common in malignant conditions (p = 0.007). Overall survival (OS), relapse-free survival (RFS), and treatment-related mortality (TRM) were 40%, 50%, and 35%, respectively. Median time of survival and relapse were 8 (IQR: 15) and 9 (IQR: 13) months, respectively.

CONCLUSION

OS was comparable to that of other low-middle-income countries. GVHD was a major challenge, along with sepsis and CMV infection. Half of the leukemias relapsed. Graft failure was a major concern in nonmalignant diseases.

Incidence, risk factors and therapy response of acute graft-versus-host disease after myeloablative hematopoietic stem cell transplantation with posttransplant cyclophosphamide

Posttransplant cyclophosphamide, sirolimus and mycophenolate mofetil (PTCy/siro/MMF) constitutes an innovative and well-tolerated acute graft-versus-host disease (aGVHD) prophylaxis after allogeneic stem cell transplantation (allo-HSCT), but risk factors for aGVHD incidence and therapy failure in this setting are scarce. This study prospectively registered all consecutive adult patients with hematologic malignancies who received a myeloablative allo-HSCT using PTCy/siro/MMF prophylaxis at our institution between 2017 and 2023. A total of 385 patients were included, of whom 44%, 34% and 22% were transplanted from matched sibiling, matched unrelated and haploidentical donors, respectively. The 180-day cumulative incidence of aGVHD was 21% (95% confidence interval [CI] 17-25%) for grade II-IV and 11% (95% CI 8-14%) grade III-IV aGVHD. The use of haploidentical donors was associated with an increased risk of severe aGVHD. Among 75 patients receiving first-line systemic corticosteroids, 49% achieved a sustained complete response, while 23% and 24% developed steroid-dependent (SD-aGVHD) and steroid-refractory aGVHD (SR-aGVHD), respectively. SR-aGVHD was associated with worse salvage treatment response and overall survival compared to SD-aGVHD. The 1-year cumulative incidence of aGVHD-related mortality was 5.4% (95% CI, 3.3-8.1). Risk factors for aGVHD-related mortality included haploidentical donors, older donors, diagnosis of myeldysplastic neoplasms, and grade IV aGVHD. This study confirms a low incidence aGVHD with PTCy/siro/MMF prophylaxis. SR-aGVHD showed poorer response to salvage therapies and worse survival, while haploidentical donors and older donor age were negative predictors for aGVHD-related deaths.

Human leukocyte antigen evolutionary divergence as a novel risk factor for donor selection in acute lymphoblastic leukemia patients undergoing haploidentical hematopoietic stem cell transplantation

Introduction

The human leukocyte antigen (HLA) evolutionary divergence (HED) reflects immunopeptidome diversity and has been shown to predict the response of tumors to immunotherapy. Its impact on allogeneic hematopoietic stem cell transplantation (HSCT) is controversial in different studies.

Methods

In this study, we retrospectively analyzed the clinical impact of class I and II HED in 225 acute lymphoblastic leukemia patients undergoing HSCT from related haploidentical donors. The HED for recipient, donor, and donor-recipient pair was calculated based on Grantham distance, which accounts for variations in the composition, polarity, and volume of each amino acid within the peptide-binding groove of two HLA alleles. The median value of HED scores was used as a cut-off to stratify patients with high or low HED.

Results

The class I HED for recipient (R_HEDclass I) showed the strongest association with cumulative incidence of relapse (12.2 vs. 25.0%, P = 0.00814) but not with acute graft-versus-host disease. The patients with high class II HED for donor-recipient (D/R_HEDclass II) showed a significantly higher cumulative incidence of severe aGVHD than those with low D/R_HEDclass II (24.0% vs. 6.1%, P = 0.0027). Multivariate analysis indicated that a high D/R_HEDclass II was an independent risk factor for the development of severe aGVHD (P = 0.007), and a high R_HEDclass I had a more than two-fold reduced risk of relapse (P = 0.028). However, there was no discernible difference in overall survival (OS) or disease-free survival (DFS) for patients with high or low HED, which was inconsistent with the previous investigation.

Discussion

While the observation are limited by the presented single center retrospective cohort, the results show that HED has poor prognostic value in OS or DFS, as well as the associations with relapse and aGVHD. In haploidentical setting, class II HED for donor-recipient pair (D/R_HEDclass II) is an independent and novel risk factor for finding the best haploidentical donor, which could potentially influence clinical practice if verified in larger cohorts.

Feasibility of co-transplantation of umbilical cord blood and third-party mesenchymal stromal cells after (non)myeloablative conditioning in patients with hematological malignancies

Umbilical cord blood (UCB) is an alternative source of stem cells for patients lacking a 9/10 or 10/10 HLA identical donor. However, after UCB transplantation, time to engraftment and immune recovery are prolonged, increasing the risk of fatal complications. Mesenchymal stromal cells (MSC) can support hematopoietic engraftment and have immunosuppressive effects. The primary objective of this phase I/II multicenter study was to determine the feasibility and safety of UCB transplantation with co-infusion of third party MSC, as assessed by treatment related mortality (TRM) at day 100. Secondary objectives were engraftment, immune recovery, occurrence of graft versus host disease (GVHD), infections, disease free survival, relapse incidence and overall survival. Eleven patients were grafted according to this protocol. Allogeneic transplantation after co-infusion appears feasible with 18 % TRM at day 100. Engraftment data show a median time of 16 days to neutrophil and 27 days to platelet recovery, which is shorter than what is usually reported after UCB transplantation. Only 1 episode of acute GVHD was reported. In conclusion, MSC and UCB co-transplantation is feasible and might help overcome some of the drawbacks of UCB transplantation.

Half a century of healing: celebrating the 50th anniversary of EBMT

EBMT is a non-profit organization with a clear mission: "to save the lives of patients with blood cancers and other life-threatening diseases by advancing the fields of blood and marrow transplantation and cell therapy worldwide through science, education and advocacy". In 1974, EBMT was established by European physicians in St. Moritz to share bone marrow transplantation (BMT) experiences and foster collaboration. Founding members included Jon Van Rood, Bruno Speck, and Eliane Gluckman. By 1989, the group expanded significantly, emphasizing mutual trust and collaboration. EBMT played a crucial role in standardizing transplant procedures, improving outcomes, and expanding access to BMT through donor registries and advancements in HLA mismatched transplants. The organization has grown to include over 7000 members worldwide and has significantly expanded its educational and training initiatives. EBMT continues to adapt to new challenges and advances in the field, including the integration of new therapies and personalized medicine. As of 2024, EBMT remains committed to its mission, embracing diversity and inclusion, and advocating for patient-centered care.

Therapeutic options for chronic myeloid leukemia following the failure of second-generation tyrosine kinase inhibitor therapy

The management of chronic myeloid leukemia in the chronic phase (CML-CP) has witnessed significant advancements since the identification of a common chromosomal translocation anomaly involving chromosomes 9 and 22, which results in the formation of the Philadelphia chromosome driven by the BCR-ABL1 fusion protein. This discovery paved the way for the development of tyrosine kinase inhibitors (TKIs) that target the adenosine triphosphate (ATP) binding site of ABL1 through the BCR-ABL-1 fusion protein. Following the approval of Imatinib by the Food and Drug Administration (FDA) as the first TKI for CML treatment in 2001, the median overall survival (OS) for chronic phase CML (CML-CP) has significantly improved, approaching that of the general population. However, achieving this milestone crucially depends on reaching certain treatment response milestones. Since the introduction of imatinib, five additional TKIs have been approved for CML-CP treatment. Despite the availability of these treatments, many patients may experience treatment failure and require multiple lines of therapy due to factors such as the emergence of resistance, such as mutations in the ATP binding site of ABL, or intolerance to therapy. This review will primarily focus on exploring treatment options for patients who fail second-generation TKI therapy due to true resistance.

Clinical characteristics and outcomes of overt gastrointestinal bleeding in children undergoing haploidentical hematopoietic stem cell transplantation: a single-center retrospective analysis

BACKGROUND

Overt gastrointestinal bleeding (GIB) is a potentially serious and life-threatening condition in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, relatively little information is available regarding overt GIB in children.

OBJECTIVES

To assess the prevalence, clinical patterns, and outcomes of overt GIB in children undergoing haploidentical hematopoietic stem cell transplantation (haplo-HSCT).

METHODS

A total of 123 consecutive patients with malignant or non-malignant blood disorders who received haplo-HSCT were reviewed in our hospital between October 2017 and October 2022. Overt GIB was determined as hematemesis, melena or hematochezia. Continuous variables were compared by Mann Whitney U test. Categorical parameters were compared by the χ2 test or Fisher's exact test. Kaplan-Meier curves and log-rank tests were used to assess overall survival (OS), non-relapse mortality (NRM) and relapse. Univariate and multivariate analyses were performed to identify potential risk factors of overt GIB development.

RESULTS

The median follow-up was 26.3 (range,1.7-74.8) months. Overt GIB occurred in 31 patients (25.2% incidence), with a median time elapsed after haplo-HSCT of 376 days (range, 58-1275 days). Compared with the non-GIB group, patients with overt GIB had reduced OS and increased NRM. In multivariate analysis, grade III-IV gut acute graft versus-host disease (aGvHD), thrombotic microangiopathy (TMA) and cytomegalovirus (CMV) viremia were significant risk factors for the occurrence of overt GIB after haplo-HSCT.

CONCLUSIONS

Overt GIB is a frequent complication after haplo-HSCT in pediatric patients, and associated with worse survival. Grade III-IV gut aGvHD, TMA and CMV viremia were associated with its development.

Vaginal complications of graft-versus-host disease after hematopoietic stem cell transplantation: a cross-sectional study

Background

Stem cell transplantation is a clinical approach used to treat certain types of cancers, such as hematologic malignancies. Graft-versus-host disease (GVHD) occurs in 30-70% of cases and often diminishes the quality of life of transplant patients. This study aimed to determine the prevalence of vaginal complications of GVHD following hematopoietic stem cell transplantation.

Methods

This study employed an analytical cross-sectional design. All patients referred to Shariati Hospital in Tehran between 2019 and 2020 who underwent hematopoietic stem cell transplantation were considered for inclusion in this study if they met the inclusion criteria. Inclusion criteria encompassed nonnot sexually active women aged 18-70 who received stem cell transplantation more than 100 days prior. Exclusion criteria comprised patients who experienced GVHD during the first 100 days posttransplantation. Additionally, individuals over 75 and patients with metastatic cancer were excluded.

Results

A total of 55 patients were recruited, with ages averaging 40±9.9 years for recipients and 38.5±12.8 years for donors. Notably, 63.3 and 58.2% of patients exhibited oral and ocular symptoms, respectively. Regarding genital involvement, 49.1% experienced vaginal symptoms, while 25.5% had vulvar involvement. Among the 27 patients with vaginal involvement, two (7.4%) were categorized as mild, 17 (63%) as moderate, and eight (29.6%) as severe. Univariate analysis identified reduced vaginal discharge [odds ratio (OR=6.56)], vaginal tightness (OR=6.23), pelvic pain (OR=5.50), and vaginal involvement (OR=3.81) as significant predictors of other organ symptoms. Moreover, vaginal involvement (OR=3.68) emerged as the sole significant predictor of the cooccurrence of oral, ocular, and other organ symptoms. In the multivariate analysis, reduced vaginal discharge (OR=8.24) and vaginal tightness (OR=3.92) significantly predicted other organ symptoms (P=0.009).

Conclusion

Reduced vaginal discharge and vaginal tightness remained significant predictors of other organ symptoms.

Longitudinal outcome over four decades of allogeneic stem cell transplantation: a single center experience

This 45-year study (1978-2022) at a single institution evaluated HSCT outcomes and complications, emphasizing recent advances, with to provide insights into HSCT's evolving field and ongoing efforts to enhance patient outcomes. Involving 1707 patients, the study revealed an initial phase (1978-1987) with a limited activity that yielded modest outcomes, a nearly three-decade span (1988-2016) with a substantial increase in transplant activity, emphasizing umbilical cord blood transplantation (UCBT) for patients lacking a suitable matched sibling donor. In addition to a gradual increase in recipient age, significant improvement in outcomes emerged in the recent period (2017-2022), marked by UCBT replacement with haploidentical transplants, introduction of PTCY-based GVHD prophylaxis for all type of transplants, and increased use of conditioning regimens with thiotepa, busulfan, and fludarabine. In this period, reductions in GVHD, non-relapse mortality, and relapse rates significantly contributed to improved overall survival, event-free survival, and GVHD-free/relapse-free survival. The study identified specific factors, including GVHD prophylaxis and donor selection changes, associated with these positive trends. This four-decade study provides a unique perspective on allogeneic HSCT, showcasing the dynamic evolution of transplantation practices and their impact on outcomes, offering valuable insights for personalized treatment approaches and emphasizing continual innovation in this critical therapeutic modality.

Dual T-cell depletion with individually tailored anti-thymocyte globulin and attenuated dose of post-transplant cyclophosphamide in haploidentical peripheral stem cell transplantation

This study aimed to assess the efficacy of dual T-cell suppression using individually tailored doses of antithymocyte globulin (ATG) and attenuated dose of post-transplant cyclophosphamide (PTCy) in haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We conducted a retrospective analysis of 78 adults with acute leukemia or myelodysplastic syndrome who underwent haplo-HSCT using intravenous busulfan and fludarabine conditioning. Thirty-two patients received attenuated ATG/PTCy, while 46 patients received ATG (7.5 mg/kg) as GVHD prophylaxis. The 100-day cumulative incidence of grade III-IV (9.7% vs. 32.4%, P = 0.018) acute GVHD, as well as 2-year moderate-severe chronic GVHD (13.9% vs. 43.9%, P = 0.018) in the ATG/PTCy group were significantly lower than those in the ATG group. The 2-year overall survival was comparable between the two groups. However, 2-year GVHD-free, relapse-free survival in the ATG/PTCy group was significantly higher compared to that in the ATG group (38.9% vs. 21.7%, P = 0.021). Moreover, during post-engraftment period, the ATG/PTCy group exhibited lower incidences of life-threatening bacterial (12.5% vs. 37%, P = 0.033) and viral infection (0% vs. 17.4%, P = 0.035) than the ATG group. In conclusion, the combination of individually tailored ATG and low-dose PTCy appears to be a promising strategy in haplo-HSCT.

Hematopoietic cell transplantation and cellular therapies in Europe 2022. CAR-T activity continues to grow; transplant activity has slowed: a report from the EBMT

In 2022, 46,143 HCT (19,011 (41.2%) allogeneic and 27,132 (58.8%) autologous) in 41,854 patients were reported by 689 European centers. 4329 patients received advanced cellular therapies, 3205 of which were CAR-T. An additional 2854 patients received DLI. Changes compared to the previous year were an increase in CAR-T treatments (+27%) and decrease in allogeneic (-4.0%) and autologous HCT (-1.7%). Main indications for allogeneic HCT were myeloid malignancies (10,433; 58.4%), lymphoid malignancies (4,674; 26.2%) and non-malignant disorders (2572; 14.4%). Main indications for autologous HCT were lymphomas (7897; 32.9%), PCD (13,694; 57.1%) and solid tumors (1593; 6.6%). In allogeneic HCT, use of sibling donors decreased by -7.7%, haploidentical donors by -6.3% and unrelated donors by -0.9%. Overall cord blood HCT decreased by -16.0%. Use of allogeneic, and to a lesser degree autologous HCT, decreased for lymphoid malignancies likely reflecting availability of new treatment modalities, including small molecules, bispecific antibodies, and CAR-T cells. Pediatric HCT activity remains stable (+0.3%) with differences between allogeneic and autologous HCT. Use of CAR-T continues to increase and reached a cumulative total of 9039 patients treated with wide differences across European countries. After many years of continuous growth, increase in application of HCT seems to have slowed down.

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.

The effect of caffeine intake and passive smoking on umbilical cord blood unit's quality parameters

Today cord blood (CB) is a valuable source of hematopoietic stem cells to treat many hematological disorders. One of the limitations of CB utilization is the reduced number of nucleated cells including stem cells. Therefore, CB banks around the world have developed strategies in an attempt to improve donor selection and the quality of the CB inventory. This study aimed to determine the impact of passive smoking and caffeine consumption on CB quality. CBs were obtained from mothers who gave birth at King Abdulaziz Medical City. All mothers gave their informed consent. Personal interviews about the mother's demographics, smoking status and exposure, and caffeine consumption executed, followed by a chart review to analyze maternal and neonatal factors. Laboratory testing was performed on all collected CB units. Using descriptive statistics, maternal and newborn factors were analyzed. T-test or Mann-Whitney U Test, as appropriate, for continuous variables analysis to study the effect of second hand smoking and coffee consumption for the primary outcome. Our study demonstrated a reduction in CB MNC, including lymphocytes, in caffeine consumers among pregnant donors, as well as a reduction in cell potency activities, including total CFU and BFU-E. The effect of passive cigarette smoking on the same cohort was insignificant. Outcome of this study will help in optimizing the quality and quantity of stem cell harvesting from CB to get the maximum benefit and such knowledge will raise the awareness among pregnant women.

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

Introduction

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

Methods

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

Results and discussion

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

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.

Phase I study of zoledronic acid combined with escalated doses of interleukine-2 for early in vivo generation of Vγ9Vδ2 T-cells after haploidentical stem cell transplant with posttransplant cyclophosphamide

The presence of donor Vγ9Vδ2 T-cells after haploidentical hematopoietic stem cell transplant (h-HSCT) has been associated with improved disease-free survival. These cells kill tumor cells in a non-MHC restricted manner, do not induce graft-versus-host disease (GVHD), and can be generated by stimulation with zoledronic acid (ZA) in combination with interleukin-2 (IL-2). This monocentric phase I, open-label, dose-escalating study (ClinicalTrials.gov: NCT03862833) aimed at evaluating the safety and possibility to generate Vγ9Vδ2 T-cells early after h-HSCT. It applied a standard 3 + 3 protocol to determine the maximum tolerated dose (MTD) of increasing low-doses of IL-2 (5 days [d] per week, 4 weeks) in combination with a single dose of ZA, starting both the first Monday after d + 15 posttransplant. Vγ9Vδ2 T-cell monitoring was performed by multiparameter flow cytometry on blood samples and compared with a control cohort of h-HSCT recipients. Twenty-six patients were included between April 2019 and September 2022, 16 of whom being ultimately treated and seven being controls who received h-HSCT only. At the three dose levels tested, 1, 0, and 1 dose-limiting toxicities were observed. MTD was not reached. A significantly higher number of Vγ9Vδ2 T-cells was observed during IL-2 treatment compared with controls. In conclusion, early in vivo generation of Vγ9Vδ2 T-cells is feasible after h-HSCT by using a combination of ZA and repeated IL-2 infusions. This study paves the way to a future phase 2 study, with the hope to document lesser posttransplant relapse with this particular adaptive immunotherapy.

Allogeneic hematopoietic stem cell transplantation for pediatric acute lymphoblastic leukemia

This study was aimed to explore the prognosis of allogenic hematopoietic stem cell transplantation (allo-HSCT) in pediatric patients with acute lymphoblastic leukemia (ALL). This retrospective case series study included children with ALL who underwent allo-HSCT at Beijing Children's Hospital of Capital Medical University, Beijing, China, between January 2009 and December 2019. The outcomes included 5-year overall survival (OS) and event-free survival (EFS). A total of 75 children (52 males) were included. The median age at presentation was 5.30 years, and the median time from diagnosis to transplantation was 1.64 years. There were 15 human leukocyte antigen (HLA)-matched and 60 HLA-semi-matched transplants, 73 complete remissions (CR), and 2 MRD-positive transplants. The median follow-up time was 41 months. Out of 75 patients, 51 children survived, and 24 died/given up at the terminal stage. The 5-year OS and EFS rates were 67.77% and 57.30%, respectively, whereas the 5-year recurrence rate was 35.69%. Acute and chronic graft versus host diseases occurred in 40 and 28 cases, respectively. Children with MLL gene fusion had higher survival rates compared to other subgroups. Haplo-HSCT is not inferior to HLA-matched transplant. The children with MLL rearrangement had an acceptable 5-year OS, while complications and relapse should be monitored.

Similar Survival But Less Chronic GVHD in Antithymocyte Globulin-Based Myeloablative Haploidentical Transplant Compared With Matched Sibling Transplant for Adult T-cell Acute Lymphoblastic Leukemia/Lymphoma

The annual number of human leukocyte antigen (HLA)-haploidentical allogeneic hematopoietic stem cell transplantation (haplo-HCT) is increasing steadily. Comparative studies about haplo-HCT versus HCT with HLA-matched sibling donors (MSD-HCT) have been tried in acute myeloid leukemia and B-cell acute lymphoblastic leukemia/lymphoma (ALL). Few studies were reported in adult T-cell ALL (T-ALL). In this retrospective study, a total of 88 consecutive patients with T-ALL were enrolled who underwent MSD-HCT (n = 24) and haplo-HCT (n = 64) with antithymocyte globulin (ATG)-based graft versus host disease (GVHD) prophylaxis between 2010 and 2022. Median follow-up for survivors was similar (43.5 [range: 7-88] months for MSD-HCT versus 43.5 (range: 6-144) months in the Haplo-HCT group). The 100-day cumulative incidence of grade II to IV acute GVHD (aGVHD) was similar, 33% (95% confidence interval [CI], 16%-52%) after MSD-HCT versus 44% (95% CI, 31%-55%) after haplo-HCT, P = 0.52. The cumulative incidences of grade III-IV aGVHD were 8% (95% CI, 1%-23%) in the MSD-HCT group and 5% (95% CI, 1%-12%) in the haplo-HCT group (P = 0.50). The 2-year cumulative incidence of chronic GVHD (limited and extensive) in the haplo-HCT, 11% (95% CI, 5%-20%) was significantly lower than that in the MSD-HCT group (42% [95% CI, 21%-62%], P = 0.002). The cumulative incidence of 4-year relapse rates (44% versus 37%, P = 0.56) and non-relapse mortality (7% versus 21%, P = 0.08) did not differ between these two groups. There were also no differences in 4-year overall survival (46% versus 47%, P = 0.44) and progression-free survival (49% versus 42%, P = 0.45) between these two groups. On multivariate analysis, using busulfan/fludarabine (BU/Flu) conditioning regimen was found to be associated with worse clinical outcome. Our results suggested that ATG-based haplo-HCT platform could work as an alternative to MSD-HCT for adult patients with T-ALL. Compared with MSD-HCT, haplo-HCT might carry a low risk for cGVHD.

Overview on novel strategies and current guidelines for hematopoietic stem cell mobilisation and collection

The success of the autologous stem cell transplantation is strictly related to an adequate hematopoietic stem cell mobilization and collection. The minimum threshold for a successful mobilization is currently defined as 2 × 106/kg CD34+ cells. However, the optimal stem cell mobilization strategy is still controversial. The availability of plerixafor, a selective and reversible CXCR4 inhibitor, has been associated with an higher use of chemo-free protocols by many centres. In the near future, it is conceivable that artificial intelligence may became more accurate and comprehensive, possibly guiding clinicians in choosing the optimal mobilisation treatment for the various patients undergoing hematopoietic stem cell transplantation. Machine learning-based scoring models may be the basis for the development of "intelligent" mobilisation algorithms.

Relapse of acute myeloid leukemia after allogeneic stem cell transplantation: immune escape mechanisms and current implications for therapy

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the expansion of immature myeloid cells in the bone marrow (BM) and peripheral blood (PB) resulting in failure of normal hematopoiesis and life-threating cytopenia. Allogeneic hematopoietic stem cell transplantation (allo-HCT) is an established therapy with curative potential. Nevertheless, post-transplant relapse is common and associated with poor prognosis, representing the major cause of death after allo-HCT. The occurrence of relapse after initially successful allo-HCT indicates that the donor immune system is first able to control the leukemia, which at a later stage develops evasion strategies to escape from immune surveillance. In this review we first provide a comprehensive overview of current knowledge regarding immune escape in AML after allo-HCT, including dysregulated HLA, alterations in immune checkpoints and changes leading to an immunosuppressive tumor microenvironment. In the second part, we draw the line from bench to bedside and elucidate to what extend immune escape mechanisms of relapsed AML are yet exploited in treatment strategies. Finally, we give an outlook how new emerging technologies could help to improve the therapy for these patients, and elucidate potential new treatment options.

PTCY-Based Haploidentical Donor Transplantation versus HLA-Matched Related and Unrelated Donor Transplantations in Patients with Refractory or Relapsed Lymphoma-A Matched-Pair Analysis

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has demonstrated its potential as a curative option for patients with r/r lymphoma. With the introduction of post-transplant cyclophosphamide-based (PTCY) graft-versus-host disease (GvHD) prophylaxis, allo-HCT using haploidentical related donors (Haplo-HSCT) has emerged as a valuable alternative for patients without an available HLA-matched donor. In this study, we compared intermediate and long-term outcomes between Haplo-HSCT and HLA-matched related donor (MRD) and unrelated donor (URD) transplantations in 16 matched pairs using age, disease status, lymphoma classification and performance status as matching criteria. Of note, 88% of patients in each group presented with active disease at the time of conditioning. After a median follow-up of >10 years, 10-year overall and progression-free survival and non-relapse mortality incidence after Haplo-HSCT were 31%, 25% and 38%, respectively, and did not differ compared to the values observed in MRD-HSCT and URD-HSCT. A remarkable lower incidence of acute GvHD ≥ II and moderate and severe chronic GvHD was observed after Haplo-HSCT compared to MRD-HSCT (50%/50%, p = 0.03/0.03) and URD-HSCT (44%/38%, p = 0.04/0.08), resulting in slightly higher 10-year GvHD-free and relapse-free survival (25%) and chronic GvHD-free and relapse-free survival (25%) in the Haplo-HSCT group. In conclusion, Haplo-HSCT is an effective treatment in patients with non-remission NHL. Given its advantage of immediate availability, haploidentical donors should be preferably used in patients with progressive disease lacking an HLA-matched related donor.

Unrelated or haploidentical allogeneic hematopoietic cell transplantation in second complete remission for acute myeloid leukemia-Improved outcomes over time: A European Society for Blood and Marrow Transplantation Acute Leukemia Working Party study

BACKGROUND

Allogeneic hematopoietic cell transplantation (allo-HCT) is the only cure for acute myeloid leukemia (AML) in second complete remission (CR2). Patients lacking a matched sibling donor (MSD) receive transplants from matched unrelated donors (MUDs), mismatched unrelated donors (MMUDs), haploidentical (haplo) donors, or cord blood.

METHODS

This is a retrospective, registry-based European Society for Blood and Marrow Transplantation study that investigates changes in patient- and transplant-related characteristics and posttransplant outcomes over time.

RESULTS

We identified 3955 adult patients (46.7% female; median age, 52 years [range, 18-78 years]) with AML in CR2 first transplanted between 2005 and 2019 from a MUD 10/10 (61.4%), MMUD 9/10 (21.9%), or haplo donor (16.7%) and followed for 3.7 years. A total of 725 patients were transplanted between 2005 and 2009, 1600 between 2010 and 2014, and 1630 between 2015 and 2019. Over the three time periods, there was a significant increase in patient age (from 48.7 to 53.5 years; p < .001), use of a haplo donor (from 4.6% to 26.4%; p < .001), and use of posttransplant cyclophosphamide (from 0.4% to 29%; p < .001). There was a significant decrease in total body irradiation and in vivo T-cell depletion. In multivariate analysis, transplants performed more recently had better outcomes. Leukemia-free survival (hazard ratio [HR], 0.79; p = .002) and overall survival (HR, 0.73; p < .001) increased over time. Similarly, nonrelapse mortality (HR, 0.64; p < .001) decreased over time. We also observed better graft-vs-host disease (GVHD) rates (acute GVHD II-IV: HR, 0.78; p = .03; GVHD-free, relapse-free survival: HR, 0.69; p < .001).

CONCLUSIONS

Even in the absence of an MSD, outcomes of allo-HCT in CR2 for AML have significantly improved over time, with most favorable outcomes achieved with a MUD.

Characterization of engraftment dynamics in myelofibrosis after allogeneic hematopoietic cell transplantation including novel conditioning schemes

Introduction

Myelofibrosis (MF) is a rare hematopoietic stem cell disorder progressing to bone marrow (BM) failure or blast phase. Allogeneic hematopoietic cell transplantation (HCT) represents a potentially curative therapy for a limited subset of patients with advanced MF, who are eligible, but engraftment in MF vs. AML is delayed which promotes complications. As determinants of engraftment in MF are incompletely characterized, we studied engraftment dynamics at our center.

Methods

A longitudinal cohort of 71 allogeneic HCT performed 2000-2019 with >50% after 2015 was evaluated.

Results

Median time to neutrophil engraftment ≥0.5x109/l was +20 days post-transplant and associated with BM fibrosis, splenomegaly and infused CD34+ cell number. Engraftment dynamics were similar in primary vs. secondary MF and were independent of MF driver mutations in JAK2, CALR and MPL. Neutrophil engraftment occurred later upon haploidentical HCT with thiotepa-busulfan-fludarabine conditioning, post-transplant cyclophosphamide and G-CSF (TBF-PTCy/G-CSF) administered to 9.9% and 15.6% of patients in 2000-2019 and after 2015, respectively. Engraftment of platelets was similarly delayed, while reconstitution of reticulocytes was not affected.

Conclusions

Since MF is a rare hematologic malignancy, this data from a large number of HCT for MF is essential to substantiate that later neutrophil and platelet engraftment in MF relates both to host and treatment-related factors. Observations from this longitudinal cohort support that novel conditioning schemes administered also to rare entities such as MF, require detailed evaluation in larger, multi-center cohorts to assess also indicators of long-term graft function and overall outcome in patients with this infrequent hematopoietic neoplasm undergoing allogeneic transplantation.

Applying Rituximab During the Conditioning Regimen Prevents Epstein-Barr Virus Infection Following Allogeneic Hematopoietic Stem Cell Transplant in a Children's Cohort: A Retrospective Case-Control Study

INTRODUCTION

Since hematopoietic stem cell transplant (HSCT) is an important therapy for malignant and non-malignant pediatric diseases, improving transplant-related mortality remains a challenge. Currently, rituximab, a monoclonal antibody of anti-CD20, is widely used for several post-HSCT complications. However, few studies have focused on the application of rituximab before HSCT.

METHODS

We conducted a retrospective case-control study from January 2019 to July 2021 to determine this effect in a single center. Forty-eight patients were included in the rituximab group, with a one-to-one ratio matched to the control group.

RESULTS

Both the occurrence rate and cumulative incidence rate of Epstein-Barr virus (EBV) infection were significantly lower in the rituximab group than in the without-rituximab group (10.4% vs. 33.3%, p = 0.014 and 12.2% vs. 39.3% p = 0.0026, respectively). Furthermore, without the application of rituximab was identified as a risk factor for post-HSCT EBV infection via both univariate [hazard ratio (HR) = 4.17, 95%CI (1.52-11.43), p = 0.005] and multivariate analyses [HR = 4.65, 95%CI (1.66-13.0), p = 0.003]. Although the overall survival (OS) probability of the rituximab group was comparable to the without-rituximab group, a markedly improved OS of the rituximab group was found in the malignant disease subgroup (78.9% vs. 42.1%, p = 0.032). The outcomes of graft-versus-host disease, neutrophil and platelet engraftment, other viral infections, and the reconstitution of lymphocytes showed no significant differences between the two groups.

CONCLUSIONS

The administration of rituximab before HSCT may prevent EBV infection following HSCT.

Second haploidentical stem cell transplantation (HAPLO-SCT2) after relapse from a first HAPLO-SCT in acute leukaemia-a study on behalf of the Acute Leukaemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

For patients with acute myeloid and lymphoblastic leukaemia (AML/ALL) lacking a matched sibling or unrelated donor, haploidentical stem cell transplantation (HAPLO-SCT) is increasingly used. However, available data on the treatment of relapse after HAPLO-SCT, including feasibility and efficacy of a second HAPLO-SCT (HAPLO-SCT2), is scarce. Hence, adults with AML/ALL, that had undergone HAPLO-SCT2 without ex-vivo manipulation after haematologic relapse from HAPLO-SCT1 were selected for a retrospective registry analysis. Eighty-two patients (AML, n = 63, ALL, n = 19, median follow-up: 33 months) were identified. Engraftment rate was 87%. At day +180, cumulative incidences of acute GvHD II-IV°/chronic GvHD were 23.9%/22.6%, respectively. Two-year overall survival/leukaemia-free survival (OS/LFS) were 34.3%/25.4%; 2-year non-relapse mortality (NRM) and relapse incidence (RI) were 17.6% and 57%. Leukaemia was the most frequent cause of death. Separated by disease, 2-year OS/LFS/NRM/RI were 28.7%/22.3%/16.2%/61.6% in AML, and 55.3%/38.4%/23.5%/38.2% in ALL patients. In a risk-factor analysis among patients with AML, stage at HAPLO-SCT1 and HAPLO-SCT2, and interval from HAPLO-SCT1 to relapse significantly influenced outcome. Our data demonstrate that HAPLO-SCT2 is a viable option in acute leukaemia relapse after HAPLO-SCT1. Engraftment, toxicity, risk factors and long-term outcome are comparable to data reported after allo-SCT2 in a matched donor setting.

Investigation of KIR/HLA relationship and other clinical variables after T-cell-replete haploidentical bone marrow transplantation in patients with acute myeloid leukemia (AML)

BACKGROUND

KIR/HLA mismatch in hematopoietic stem cell transplantation (HSCT), particularly in patients with acute myeloid leukemia (AML), was related to decreased recurrence rates, improved engraftment, and a reduction in graft-versus-host disease, according to recent research (GVHD). Uncertainty exists about the impact of KIR/HLA mismatch on haploidentical-HSCTs treated with post-transplant cyclophosphamide (PTCy). We attempted to analyze the effects of KIR/HLA mismatch on clinical outcomes on transplant outcomes using the cohort of 54 AML patients who received a haplo-HSCT with PTCy.

RESULTS

In contrast to KIR/HLA match, our findings showed that donor KIR/HLA mismatch was substantially associated with superior OS (HR, 2.92; (P = 0.04)). Moreover, donor KIR/HLA mismatch (KIR2DS1_D/C2⁺ _R and KIR2DS2_D/C1⁺ _R mismatch versus KIR2DL1_D/C2^- _R mm, KIR2DL2/3_D/C1^- _R mm and KIR3DL1_D/Bw4^- mm) was correlated with the improvements in OS (HR, 0.74; P = 0.085) and activating. KIR/HLA mismatch versus KIR/HLA match was significantly correlated with improvements in OS (HR, .46; P = 0.03) and inhibitory. KIR/HLA mismatch versus KIR/HLA match was enhancement in the OS (HR, .93; P = 0.06). Despite a higher rate of aGvHD (grade I-IV) in the patients with KIR/HLA mismatch compared to KIR/HLA matched (57% vs. 33% (p = 0.04). However, the KIR/HLA mismatch group saw a decreased relapse rate (3.2% vs. 23%, p = 0.04).

CONCLUSION

This analysis shows the significance of KIR/HLA Incompatibility, other clinical variables like CMV, the relationship between donor/recipient and donor age, and the relationship between donor/recipient and donor age in the haplo-donor selection process. It also suggests that KIR and HLA mismatching between donor and recipient could be routinely performed for haplo-donor selection and may improve clinical outcomes after haplo-HSCTs with PTCy.

αβ+ /CD19+ -depleted haploidentical stem cell transplantation for children with acute leukemia: Is there a protective effect of increased γδ+ T-cell content in the graft?

BACKGROUND

Haploidentical hematopoietic stem cell transplantation (HSCT) with depletion of αβ⁺ T cells and CD19⁺ B cells has emerged as a viable alternative to traditional donors for treating acute leukemia in children. As the use of this innovative approach continues to grow and more experience is gained, it is essential to identify and comprehend the key factors that contribute to successful transplantation and improved outcomes.

METHODS

We conducted a retrospective analysis of single-center data from 27 children with acute lymphoblastic leukemia and 11 children with acute myeloid leukemia who underwent haploidentical HSCT with depletion of αβ⁺ T cells and CD19⁺ B cells between the years 2013 and 2020.

RESULTS

Engraftment was successful in 35 out of 38 patients (92%), who were all children conditioned using either a total body irradiation-based regimen or a treosulfan, fludarabine, and thiotepa regimen engrafted successfully. The 5-year overall survival and event-free survival rates were 51% and 42%, respectively. There were no cases of grade III-IV acute graft-versus-host disease, and only two patients developed chronic graft-versus-host disease. Patients with a higher content of γδ⁺ T cells in the graft demonstrated a longer event-free survival.

CONCLUSIONS

αβ⁺ /CD19⁺ -depleted haploidentical hematopoietic stem cell transplantation can offer long-term remission for children with acute leukemia with minimal graft-versus-host disease.

Effects of different types of allogeneic hematopoietic stem cell transplantation donors on Philadelphia chromosome-positive acute lymphoblastic leukemia during the tyrosine kinase inhibitor era: A systematic review and meta-analysis

BACKGROUND

Matched donor (MD) allogeneic hematopoietic stem cell transplantation (allo-HSCT) is currently the preferred choice of treatment for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) patients who have achieved complete remission. This systematic review and meta-analysis was conducted to investigate the effects of allo-HSCTs from different donor types for Ph+ ALL patients who received tyrosine kinase inhibitors (TKIs).

METHODS

Studies in EMBASE and MEDLINE between inception and December 2020 were identified using search terms related to "Ph+ ALL" and "HSCT." Eligible studies were studies with Ph+ ALL patients who received a TKI and allo-HSCT. The primary outcomes of interest-the overall survival (OS) or relapse-free survival (RFS)-needed to be reported. The Mantel-Haenszel method was used to combine the effect estimates and associated 95% confidence intervals (CIs) of each donor type.

RESULTS

Fourteen cohort studies were identified for the meta-analysis. Haploidentical (HID)-HSCT for Ph+ ALL patients resulted in a superior RFS to MD-HSCT, with a pooled odds ratio (OR) of 1.57 (95% CI, 1.05-2.32; I2 = 0%). However, HID-HSCT and MD-HSCT had comparable OS. Furthermore, HID-HSCT group had a significantly lower relapse rate than MD-HSCT group. On the other hand, the risks of graft-versus-host disease (GvHD) were higher for HID-HSCT and pooled OR of chronic GvHD rate. The OS and RFS of matched sibling-HSCT, matched unrelated-HSCT, and cord blood-HSCT were comparable with those of HID-HSCT.

CONCLUSION

This systematic review and meta-analysis showed that HID-HSCT is as effective as MD-HSCT in Ph+ ALL patients.

The Benefits of the Post-Transplant Cyclophosphamide in Both Haploidentical and Mismatched Unrelated Donor Setting in Allogeneic Stem Cells Transplantation

Allogeneic hematopoietic cell transplantation (alloHSCT) is a standard therapeutic approach for acute leukemias and many other hematologic malignancies. The proper choice of immunosuppressants applicable to different types of transplantations still requires strict and careful consideration, and data in this regard are divergent. For this reason, in this single-centered, retrospective study, we aimed to compare the outcome of 145 patients who received post-transplant cyclophosphamide (PTCy) for MMUD and haplo-HSCT or GvHD prophylaxis for MMUD-HSCT alone. We attempted to verify if PTCy is an optimal strategy in MMUD setting. Ninety-three recipients (93/145; 64.1%) underwent haplo-HSCT while 52 (52/145; 35.9%) underwent MMUD-HSCT. There were 110 patients who received PTCy (93 in haplo and 17 in MMUD group) and 35 patients received conventional GvHD prophylaxis based on antithymocyte globulin (ATG), cyclosporine (CsA), and methotrexate (Mtx) in the MMUD group only. Our study revealed that patients receiving post-transplant cyclophosphamide (PTCy) show decreased acute GvHD rates and CMV reactivation as well as a statistically lower number of CMV copies before and after antiviral treatment compared to the CsA + Mtx + ATG group. Taking into account chronic GvHD, the main predictors are donor age, ≥40 years, and haplo-HSCT administration. Furthermore, the survival rate of patients following MMUD-HSCT and receiving PTCy with tacrolimus and mycophenolate mofetil was more than eight times greater in comparison to patients receiving CsA + Mtx + ATG (OR = 8.31, p = 0.003). These data taken together suggest that the use of PTCy displays more benefits in terms of survival rate compared to ATG regardless of the type of transplantation performed. Nevertheless, more studies with a larger sample size are required to confirm the conflicting results in the literature studies.

Benchmarking of survival outcomes following Haematopoietic Stem Cell Transplantation (HSCT): an update of the ongoing project of the European Society for Blood and Marrow Transplantation (EBMT) and Joint Accreditation Committee of ISCT and EBMT (JACIE)

From 2016 EBMT and JACIE developed an international risk-adapted benchmarking program of haematopoietic stem cell transplant (HSCT) outcome to provide individual EBMT Centers with a means of quality-assuring the HSCT process and meeting FACT-JACIE accreditation requirements relating to 1-year survival outcomes. Informed by previous experience from Europe, North America and Australasia, the Clinical Outcomes Group (COG) established criteria for patient and Center selection, and a set of key clinical variables within a dedicated statistical model adapted to the capabilities of the EBMT Registry. The first phase of the project was launched in 2019 to test the acceptability of the benchmarking model through assessment of Centers' performance for 1-year data completeness and survival outcomes of autologous and allogeneic HSCT covering 2013-2016. A second phase was delivered in July 2021 covering 2015-2019 and including survival outcomes. Reports of individual Center performance were shared directly with local principal investigators and their responses were assimilated. The experience thus far has supported the feasibility, acceptability and reliability of the system as well as identifying its limitations. We provide a summary of experience and learning so far in this 'work in progress', as well as highlighting future challenges of delivering a modern, robust, data-complete, risk-adapted benchmarking program across new EBMT Registry systems.

Hematopoietic cell transplantation and cellular therapies in Europe 2021. The second year of the SARS-CoV-2 pandemic. A Report from the EBMT Activity Survey

In 2021, 47,412 HCT (19,806 (42%) allogeneic and 27,606 (58%) autologous) in 43,109 patients were reported by 694 European centers. 3494 patients received advanced cellular therapies, 2524 of which were CAR-T treatments, an additional 3245 received DLI. Changes compared to the previous year were CAR-T treatment (+35%), allogeneic HCT +5.4%, autologous HCT +3.9%, more pronounced in non-malignant disorders. Main indications for allogeneic HCT were myeloid malignancies 10,745 (58%), lymphoid malignancies 5127 (28%) and non-malignant disorders 2501 (13%). Main indications for autologous HCT were lymphoid malignancies 22,129 (90%) and solid tumors 1635 (7%). In allogeneic HCT, use of haploidentical donors decreased by -0.9% while use of unrelated and sibling donors increased by +4.3% and +9%. Cord blood HCT decreased by -5.8%. Pediatric HCT increased overall by +5.6% (+6.9% allogeneic and +1.6% autologous). Increase in the use of CAR-T was mainly restricted to high-income countries. The drop in HCT activity reported in 2020 partially recovered in 2021, the second year of the SARS-CoV-2 pandemic. The transplant community confronted with the pandemic challenge, continued in providing patients access to treatment. This annual EBMT report reflects current activities useful for health care resource planning.

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.

The effect of pre-conditioning immunoglobulin and absolute lymphocyte count on the outcomes of allogeneic hematopoietic cell transplantation

INTRODUCTION

The prevention of mortality and morbidity related to the increasingly used allogeneic hematopoietic cell transplantation (allo-HCT), along with the effects of pre- and post-transplant immune status on transplant outcomes, have become the focus of the studies conducted on this subject in recent years. In parallel, this study was designed to investigate the effects of pre-conditioning immunoglobulin (pre-conditioning-Ig) and pre-conditioning absolute lymphocyte count (pre-conditioning-ALC) levels on transplant outcomes.

METHODS

This study was designed as a retrospective, observational and cross-sectional study. The objective of the study is to investigate the effects of pre-conditioning-Ig and ALC levels primarily on the rate of patients with febrile neutropenia (FEN) and the duration of FEN and length of hospital stay (LoS), and secondarily on acute graft-versus-host disease (aGVHD), cytomegalovirus (CMV) viremia, and mortality in the acute leukemia patients who underwent allo-HCT.

RESULTS

A total of 104 acute leukemia patients, of whom 55 had acute lymphoblastic leukemia (ALL) and 49 had acute myeloid leukemia (AML), were included in the study. Compared to the AML group, the median pre-conditioning-IgG, IgA, and IgM levels were found to be significantly lower in the ALL group (11.3 vs. 6.6, p < 0.001; 1.8 vs. 0.9, p < 0.001; and 0.7 vs. 0.4, p < 0.001; respectively). But, there was no significant difference between the groups in pre-conditioning-Ig and ALC levels and transplant outcomes. However, subgroup analysis revealed that high pre-conditioning-ALC levels were significantly correlated with aGVHD levels (Odds Ratio: 1.02; p = 0.034) and low pre-conditioning-IgM levels were significantly correlated with increased mortality rate (Hazard Ratio: 0.08; p = 0.042) in AML patients.

CONCLUSION

The significant difference determined between the ALL and AML groups in pre-conditioning-Ig levels was not reflected on the effects of pre-conditioning-Ig and ALC levels on transplant outcomes. However, we observed that pre-conditioning-IgM and ALC levels have an impact on transplant outcomes in AML patients.

Haploidentical haematopoietic stem cell transplantation for TP53-mutated acute myeloid leukaemia

Acute myeloid leukaemia (AML) patients with tumour protein p53 (TP53) mutations are often resistant to chemotherapy and have worse clinical outcomes than patients without TP53 mutations. In this study, we compared clinical outcomes of patients with AML with and without TP53 mutations who underwent haploidentical haematopoietic stem cell transplantation (haplo-HSCT). For the TP53-mutation group and TP53 wild-type group, the 2-year cumulative incidence of relapse (CIR) was (39.0% vs. 21.2% respectively, p = 0.088), the 2-year non-relapse mortality (NRM) rate was (3.2% vs. 8.4% respectively, p = 0.370), the 2-year leukaemia-free survival (LFS) was (57.7% vs. 71.3% respectively, p = 0.205), the 2-year overall survival (OS) rate was (69.9% vs. 81.3% respectively, p = 0.317), the 100-day cumulative incidence of Grade II-IV acute graft-versus-host disease (GvHD) was (6.5% vs. 20.7% respectively, p = 0.074), the 2-year cumulative incidence of chronic GvHD was (52.3% vs. 53.1% respectively, p = 0.493) and the 2-year GvHD-free/relapse-free survival (GRFS) was (57.7% vs. 69.6% respectively, p = 0.347). Our data showed that there were no significant differences in 2-year clinical outcomes between the two groups. Multivariable analysis showed TP53 mutations had no significant impact on CIR, NRM, OS, GvHD, LFS or GRFS. Our findings suggest that patients with AML with TP53 mutations may at least partially benefit from haplo-HSCT. Haplo-HSCT might be the recommended treatment for such patients.

Outcomes associated with allogeneic hematopoietic stem cell transplantation for relapsed and refractory Hodgkin lymphoma in the era of novel agents

BACKGROUND

Relapsed or refractory Hodgkin lymphoma (R/R HL) is a challenging disease with limited treatment options beyond brentuximab vedotin and checkpoint inhibitors. Herein we present the time-trend analysis of R/R HL patients who received allogeneic hematopoietic cell transplantation (allo-HCT) at our center from 2001-2017.

METHODS

The patients were divided into two distinct treatment cohorts: era1 (2001-2010), and era2 (2011-2017). The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), non-relapse mortality (NRM), and cumulative incidence of acute and chronic graft versus host disease (GVHD).

RESULTS

Among the 51 patients included in the study, 29 were in era1, and 22 were in era2. There was decreased use of myeloablative conditioning in era2 (18% vs. 31%) compared to era1 and 95% of patients in era2 previously received brentuximab Vedotin (BV). Haploidentical donors were seen exclusively in era2 (0% vs. 14%) and more patients received alternative donor transplants (7% vs. 32%) in era2. The 4-year OS (34% vs. 83%, p < 0.001) and 4-year PFS (28% vs. 62%, p = 0.001) were significantly inferior in era1 compared to era2. The incidence of 1-year NRM was lower in era2 compared to era1 (5% vs. 34%, p = 0.06). The cumulative incidence of acute GVHD at day 100 was similar in both eras (p = 0.50), but the incidence of chronic GVHD at 1 year was higher in era2 compared to era1 (55% vs. 21%, p = 0.03).

CONCLUSIONS

Despite the advent of novel therapies, allo-HCT remains an important therapeutic option for patients with R/R HL.

Comparison of NK alloreactivity prediction models based on KIR-MHC interactions in haematopoeitic stem cell transplantation

The biological processes underlying NK cell alloreactivity in haematopoietic stem cell transplantation (HSCT) remain unclear. Many different models to predict NK alloreactivity through KIR and MHC genotyping exist, raising ambiguities in its utility and application for clinicians. We assessed 27 predictive models, broadly divided into six categories of alloreactivity prediction: ligand-ligand, receptor-ligand, educational, KIR haplotype-based, KIR matching and KIR allelic polymorphism. The models were applied to 78 NGS-typed donor/recipient pairs undergoing allogeneic HSCT in genoidentical (n=43) or haploidentical (n=35) matchings. Correlations between different predictive models differed widely, suggesting that the choice of the model in predicting NK alloreactivity matters. For example, two broadly used models, educational and receptor-ligand, led to opposing predictions especially in the genoidentical cohort. Correlations also depended on the matching fashion, suggesting that this parameter should also be taken into account in the choice of the scoring strategy. The number of centromeric B-motifs was the only model strongly correlated with the incidence of acute graft-versus-host disease in our set of patients in both the genoidentical and the haploidentical cohorts, suggesting that KIR-based alloreactivity, not MHC mismatches, are responsible for it. To our best knowledge, this paper is the first to experimentally compare NK alloreactivity prediction models within a cohort of genoidentical and haploidentical donor-recipient pairs. This study helps to resolve current discrepancies in KIR-based alloreactivity predictions and highlights the need for deeper consideration of the models used in clinical studies as well as in medical practice.

Correlative factors of ocular surface lesions after allogeneic hematopoietic stem cell transplantation: A retrospective study

BACKGROUND

Ocular graft-versus-host disease (oGVHD) is one of the complications after allogeneic hematopoietic stem cell transplantation (HSCT), which impairs the quality of life and may indicate poor prognosis. In this retrospective study, the aim was to investigate the characteristics of ocular surface after HSCT, and analyze the risk factors related to the severity of ocular surface lesions.

METHODS

248 post-HSCT patients were enrolled in this retrospective study. Subjects were divided into no lesion group, mild lesion group and severe lesion group, according to the severity of ocular surface lesions. The correlations between grades of ocular surface lesions and gender, age, primary disease, donor source, human leukocyte antigen (HLA) type, kinship, donor-recipient relationship, blood type, source of stem cell and systemic GVHD were analyzed.

RESULTS

The median scores of corneal epitheliopathy, lid margin lesions and meibomian gland loss were 3, 6 and 2 points, respectively. The grade of corneal epitheliopathy was related to donor source (P<0.001), kinship (P=0.033), HLA-matching (P<0.001), and systemic GVHD (P=0.007), especially oral GVHD (P<0.001) and liver GVHD (P=0.002). The grade of lid margin lesions was related to donor source (P=0.019), HLA-matching (P=0.006), and systemic GVHD (P=0.013), especially skin GVHD (P=0.019) and oral GVHD (P=0.019). The grade of meibomian gland loss was related to age (P=0.035) and gastrointestinal GVHD (P=0.007). The grade of corneal epitheliopathy after HSCT was related to the lid margin lesion score (P<0.001).

CONCLUSIONS

The occurrence and development of ocular GVHD are mostly accompanied by the history of systemic GVHD. While in few cases, ocular surface lesions related to GVHD can be observed prior to the rejection of other tissues and organs. Severe corneal epitheliopathy occurs in patients with severe lid margin lesions in ocular GVHD. The lesions of corneal epithelium and lid margin are milder in HLA partially matching transplantation.

The late outcomes of syngeneic hematopoietic stem cell transplantation in patients with blood disorders

Introduction. Syngeneic hematopoietic stem cell transplantation is a type of allogeneic stem cell transplantation when the donor of stem cells is a genetically identical (monozygotic) twin of the recipient. After this type of transplantation, there is no immunological conflict as the graft versus host disease, but at the same time, there is no positive effect of the graft-versus-leukemia effect.

Aim: to assess the overall survival, event-free survival, probability of relapse, and transplant-related mortality rates associated with syngeneic stem cell transplantation.

Patients and methods. In the National Research Center for Hematology from January 1988 to December 2018 we performed 654 allo-HSCT: 17 (2.5%) of them from a syngeneic donor. We performed a «paired analysis» with patients after allo-HSCT from a HLA-identical sibling donor. We included patients after allo-HSCT from an HLA-identical related donor (n = 28) in Group 1 and patients after syngeneic stem cell transplantation in group 2 (n = 14). Patients with aplastic anemia (n = 3) were excluded from the «paired analysis».

Results. Patients after syngeneic stem cell transplantation did not develop a graft-versus-host disease. The relapse developed in 50% of cases (n = 7). Five patients (35.7%) died: 4 of them due to the relapse of the disease, and 1 – due to the graft failure. The relapse probability in patients after syngeneic HSCT was higher and amounted to 18.4% versus 54.2% (p = 0.047) for allo-HSCT from HLA-identical sibling donor and a syngeneic donor, respectively. Overall and event-free survival in patients after syngeneic HSCT is comparable to those in patients after allo-HSCT from an HLA-identical sibling donor.

Conclusion. Syngeneic hematopoietic stem cell transplantation is justified in the absence of another related or unrelated donor of hematopoietic stem cells. The use of myeloablative conditioning regimens, peripheral blood stem cells as a source of stem cells, or high doses of nucleated cells/kg in the case of using bone marrow will improve post-transplant parameters in patients after syngeneic hematopoietic stem cell transplantation.

Haploidentical Versus Matched Sibling Donor Hematopoietic Stem Cell Transplantation for Adult Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia: A Study From the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

The results of haploidentical stem cell transplantation (haploHCT) for patients with acute lymphoblastic leukemia (ALL) transplanted in active disease remain largely unknown. We retrospectively analyzed adult patients with R/R ALL who underwent haploHCT or matched sibling donor (MSD-HCT) as a first transplantation between 2012 and 2020. The analysis comprised 274 patients, 94 had a haploHCT, and 180 had an MSD-HCT. The median follow-up was 32 months. The median age was 33 (range 18-76) and 37 (18-76) years in the haplo- and MSD-HCT groups, respectively. Post-transplant cyclophosphamide (PTCy) was used in 88% of haploHCT and in 4% of the MSD-HCT group. Graft-versus-host disease grade III-IV was higher in haploHCT than in the MSD-HCT group (18% versus 9%; P = 0.042). The 2-year chronic (c) graft-versus-host disease rates were 17% versus 33% (hazard ratio [HR] = 0.56; P = 0.14), respectively. By multivariate analysis, relapse incidence, and leukemia-free survival were not significatively different between the transplant groups, while nonrelapse mortality (NRM) was significantly higher (25% versus 18% at 2 years; HR = 2.03; P = 0.042) and overall survival (OS) lower (22% versus 38% at 2 years; HR = 1.72; P = 0.009) in the haploHCT group compared with the MSD-HCT group. We conclude that the 2-year OS of R/R ALL patients undergoing MSD transplants is significantly better than in haploHCT with a higher NRM in the latter.

Modified combination of anti-thymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy) as compared with standard ATG protocol in haploidentical peripheral blood stem cell transplantation for acute leukemia

In haploidentical peripheral blood stem cell transplantation (haplo-PBSCT), the combination of anti-thymocyte globulin and post-transplant cyclophosphamide (ATG/PTCy) has a synergistic impact in preventing graft-versus-host disease (GvHD). However, little is known about the long-term consequences of the new combination approach. Our goal is to evaluate the efficacy of ATG/PTCy versus a standard ATG regimen by focusing at long-term outcomes in a more homogeneous group of patients. We retrospectively included 118 adult patients up to 60 years with acute leukemia who underwent haplo-PBSCT at our single institution, following the same myeloablative conditioning regimen. From 2010 to 2020, 78 patients received a modified combination of ATG (2.5 mg/kg/day, on days −3, −2, and −1) and PTCy (40 mg/kg/day on days +3 and +4) compared to 40 patients who had a standard ATG-based regimen (2.5 mg/kg/day from days −4 to −1) from 2008 to 2015. The median follow-up time for all patients was 5.36 years, respectively. The cumulative incidence (CI) of neutrophil and platelet engraftment, as well as CMV reactivation, did not differ statistically between the two groups. The CI of the acute GvHD of grades II–IV and III–IV and extensive chronic GvHD were considerably lower in the ATG/PTCy (34.6%, 8.97%, and 13.63%) than in the ATG cohort (57.5%, 30%, and 38.23%) as validated by multivariable modeling. Additionally, compared to the ATG arm, the ATG/PTCy was a hazard factor associated with a higher risk of relapse (HR = 2.23, p = 0.039). The probability of 5-year overall survival, disease-free survival, and GvHD-free relapse-free survival in the ATG/PTCy group (53.34%, 49.77%, and 36.04%) was comparable with the ATG group (47.5%, 42.5%, and 22.5%), respectively. Our finding suggested that a modified ATG/PTCy combination resulted in a lower risk of acute and chronic GvHD and a higher risk of relapse than the standard ATG-based protocol but had no effect on long-term outcomes. However, certain adjustments in the immunosuppression protocol are warranted to improve the outcome.

Donor specific HLA antibody in hematopoietic stem cell transplantation: Implications for donor selection

Advances in hematopoietic stem cell transplant (HSCT) have led to changes in the approach to donor selection. Many of these new approaches result in greater HLA loci mismatching, either through the selection of haploidentical donors or permissive HLA mismatches. Although these approaches increase the potential of transplant for many patients by expanding the number of acceptable donor HLA genotypes, they add the potential barrier of donor-specific HLA antibodies (DSA). DSA presents a unique challenge in HSCT, as it can limit engraftment and lead to graft failure. However, transient reduction of HLA antibodies through desensitization treatments can limit the risk of graft failure and facilitate engraftment. Thus, the consideration of DSA in donor selection and the management of DSA prior to transplant are playing an increasingly important role in HSCT. In this review, we will discuss studies addressing the role of HLA antibodies in HSCT, the reported impact of desensitization on DSA levels, and the implications for selecting donors for patients with DSA. We found that there is a clear consensus that moderate strength DSA should be avoided, while desensitization strategies are reported to be effective in most cases at reducing DSA to amenable levels. There is limited information regarding the impact of specific characteristics of DSA, such as HLA loci or overall level of sensitization, which could further aid in donor selection for sensitized HSCT candidates.

Comparison of Outcomes of Haploidentical Peripheral Blood Stem Cell Transplantation Supported by Third-Party Cord Blood Versus Human Leukocyte Antigen-Matched Sibling Peripheral Blood Stem Cell Transplantation in Hematologic Malignancy Patients

Recent studies have shown that haploidentical hematopoietic stem cell transplantation supported by third-party cord blood (haplo-cord-HSCT) results in rapid hematopoietic recovery, low incidences of graft-versus-host disease (GVHD), and relapse of hematologic malignancies. However, few reports on haploidentical peripheral blood stem cell transplantation supported by third-party cord blood (haplo-cord-PBSCT) have been published. To evaluate the outcomes of patients who underwent haplo-cord-PBSCT or human leukocyte antigen (HLA)-matched sibling donor peripheral blood stem cell transplantation (MSD-PBSCT), we retrospectively reviewed the clinical data of patients with hematologic malignancies who underwent haplo-cord-PBSCT (n = 93) or MSD-PBSCT (n = 72) in our hospital from March 2017 to December 2020. In the haplo-cord-PBSCT and MSD-PBSCT groups, the median time for neutrophil and platelet engraftment was 13 vs. 12 days (p = 0.07) and 16 vs. 13 days (p = 0.06), respectively. The 30-day cumulative incidences of neutrophil engraftment were 100.0% and 98.6% (p = 0.12). The 100-day cumulative incidences of platelet engraftment were 96.8% and 98.6% (p = 0.01). The 100-day cumulative incidences of grade II–IV and grade III–IV acute GVHD were 29.1% vs. 23.6% (p = 0.42) and 9.7% vs. 4.2% (p = 0.18). The cumulative incidences of total and moderate/severe chronic GVHD at 1 year were 26.5% vs. 17.4% and 8.1% vs. 4.5%, respectively, and at 3 years were 34.7% vs. 34.3% (p = 0.60) and 13.6% vs. 10.6% (p = 0.49), respectively. The cumulative incidences of relapse at 1 year were 9.3% and 7.2% and at 3 years were 17.0% and 17.0% (p = 0.98). Non-relapse mortality (NRM) at 1 year was 14.6% and 8.6% and at 3 years was 17.4% and 8.6% (p = 0.13) in two groups. The probabilities of overall survival (OS), disease-free survival (DFS), and GVHD-free/relapse-free survival (GRFS) at 1 year were 81.7% vs. 88.6%, 76.1% vs. 84.2%, and 71.7% vs. 79.7%, respectively, and at 3 years were 78.7% vs. 79.0%, 65.6% vs. 74.4%, and 55.5% vs. 63.6%, respectively, in the corresponding group, p > 0.05. In conclusion, for patients with acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) and acute lymphoid leukemia (ALL), haplo-cord-PBSCT results in similar outcomes compared with MSD-PBSCT, and it may be a valid alternative transplantation method.

Outcomes of haploidentical peripheral stem cell transplantation with combination of post-transplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG) compared to unrelated donor transplantation in acute myeloid leukemia: A retrospective 10-year experience

In the evolution of haploidentical hematopoietic stem cell transplantation (haplo-HSCT), In vivo T-cell modulation with concomitant use of anti-thymocyte globulin (ATG) and high-dose post-transplant cyclophosphamide (PTCy) provides a novel promising method on transplant outcomes; however, the long-term effects of this therapy are mostly unknown. We retrospectively compared the long-term outcomes of adult acute myeloid leukemia (AML) patients undergoing a haplo-HSCT (n = 92) with a new modified combination of ATG and PTCy in the context of peripheral blood stem cell (PBSC) and myeloablative conditioning (MAC) with an otherwise similar group of AML patients who received an unrelated donor (URD) HSCT (n = 57) with ATG protocol from February 2010 to December 2020 at our single-center (HORCSCT). Median follow-up was 3.73 and 4.28 years for haploidentical and URD-HSCT, respectively. In haplo-HSCT, the cumulative incidence of grades II-IV and III-IV acute graft versus host disease (aGvHD) and extensive chronic GvHD (cGvHD) was much lower than in URD (27% versus 56% for grades II-IV, 8.7% versus 24.5% for grades III-IV, and 15.4% versus 34.7% for extensive cGvHD, respectively). Five-year overall survival (OS) was 54.03% for haplo and 54.48% for URD (p = 0.927); GvHD-free relapse-free survival (GRFS) was 44.1% and 29.86% (p = 0.149); relapse incidence was 15.79% and 26.95% (p = 0.72); and non-relapse mortality (NRM) was 29.48% and 26.32% (p = 0.73), respectively. Using multivariable analyses, when compared to Haplo, URD was a significant predictor of relapse (HR=1.80, p = 0.039); however, no difference in OS, GRFS, and NRM was noted between haplo and URD. Therefore, given the favorable results with haplo-HSCT and considering donor availability promptly with low cost, it conservatively suggested that haplo-HSCT with the introduced protocol could be viewed as the first alternative for patients with AML in the absence of matched sibling donors.