Risk factors and survival outcomes in children with early cardiotoxicity after allogeneic hematopoietic stem cell transplantation

Cardiotoxicity in children is a potentially fatal complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT); therefore, early identification of risk factors can improve patient prognosis. However, there are few data on the clinical characteristics of early-stage cardiotoxicity in children after allo-HSCT. We conducted a retrospective single-center study of pediatric patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) between January 2016 and December 2022 at the Children's Hospital Affiliated with Chongqing Medical University to evaluate the clinical characteristics of early cardiac events (ECEs) after allo-HSCT and their impact on survival outcomes. We enrolled 444 patients who underwent allo-HSCT-304 males (68%) and 140 females (32%)-with a median age of 3.3 years (1.8-6.5 years) at transplantation. We found that 73 patients (16.4%) had ECEs after allo-HSCT. The ECEs included valvular disease (n = 46), pericardial effusion (n = 38), arrhythmia (n = 9), heart failure (n = 16), and dilated cardiomyopathy (n = 1). Female sex, age ≥ 6 years, body mass index (BMI) < 16 kg/m2 and HLA-type mismatches were risk factors for ECEs. We designed a stratified cardiac risk score that included these risk factors, and the higher the score was, the greater the cumulative incidence of ECEs. The occurrence of an ECE was closely associated with a lower overall survival (OS) rate and greater nonrelapse mortality (NRM). In addition, stratified analysis based on the number of combined ECEs showed that the greater the number of combined ECEs was, the more significant the negative impact on OS rates.

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.

Low dose post-transplant cyclophosphamide and sirolimus induce mixed chimerism with CTLA4-Ig or lymphocyte depletion in an MHC-mismatched murine allotransplantation model

Allogeneic hematopoietic cell transplantation (allo-HCT) offers a curative option for patients with certain non-malignant hematological diseases. High-dose post-transplant cyclophosphamide (PT-Cy) (200 mg/kg) and sirolimus (3 mg/kg), (HiC) synergistically induce stable mixed chimerism. Further, sirolimus and cytotoxic T lymphocyte-associated antigen-4 immunoglobulin (CTLA4-Ig), also known as Abatacept (Aba), promote immune tolerance and allograft survival. Here, in a major histocompatibility complex (MHC)-mismatched allo-HCT murine model, we combined Aba and/or T-cell depleting anti-Thy1.2 (Thy) with a lower dose of PT-Cy (50 mg/kg) and Sirolimus (3 mg/kg), (LoC). While mice in the LoC group showed graft rejection, the addition of Thy to LoC induced similar donor chimerism levels when compared to the HiC group. However, the addition of Aba to LoC led to graft acceptance only in younger mice. When Thy was added to the LoC+Aba setting, graft acceptance was restored in both age groups. Engrafted groups displayed significantly reduced frequencies of recipient-specific interferon-γ-producing T cells as well as an increased frequency in regulatory T cells (Tregs) except in the LoC+Aba group. Splenocytes from engrafted mice showed no proliferation upon restimulation with Balb/c stimulators. Collectively, in combination with Aba or Thy, LoC may be considered to reduce graft rejection in patients who undergo allo-HCT.

Post-Transplant Cyclophosphamide versus Anti-Thymocyte Globulin in Patients with Hematological Malignancies Treated with Allogeneic Hematopoietic Stem Cell Transplantation from Haploidentical and Matched Unrelated Donors: A Real-Life Experience

Background: Post-transplant cyclophosphamide (PTCY) is widely used as graft versus host disease (GvHD) prophylaxis in allogeneic hematopoietic stem cell transplant (HSCT) recipients, with reported clinical benefits in patients who underwent transplant from a matched unrelated donor (MUD). However, real-life data on clinical efficacy and safety of PTCY in haploidentical and MUD transplantations are still poor. Methods: In our real-life retrospective observational study, we included a total of 40 consecutive adult patients who underwent haploidentical or MUD HSCT for various hematological malignancies and who received PTCY (n = 24) or ATG (n = 16) as GvHD prophylaxis at Hematology Units from hospitals of Salerno and Avellino, Italy, and clinical outcomes were compared. Results: We showed protective effects of PTCY against disease relapse with the relapse rate after transplantation of 16% versus 50% in the ATG arm (p = 0.02). All-cause mortality was lower (36% vs. 75%; p = 0.02) and the 2-year overall survival was slightly superior in patients administered PTCY (61% vs. 42%; p = 0.26). Conclusions: We support the use of PTCY, even in a real-life setting; however, the optimization of this protocol should be further investigated to better balance relapse prevention and GvHD prophylaxis.

Impact of post-transplant cyclophosphamide (PTCy)-based prophylaxis in matched sibling donor allogeneic haematopoietic cell transplantation for patients with myelodysplastic syndrome: a retrospective study on behalf of the Chronic Malignancies Working Party of the EBMT

We retrospectively compared outcomes of 404 MDS patients undergoing 1st matched sibling donor allo-HCT receiving either PTCy-based (n = 66) or other "conventional prophylaxis" (n = 338; mostly calcineurin inhibitor + methotrexate or MMF). Baseline characteristics were balanced, except for higher use of myeloablative regimens in the PTCy group (52.3% vs. 38.2%, p = 0.047). Incidences of neutrophil (Day +28: 89% vs. 97%, p = 0.011) and platelet (Day +100: 89% vs. 97%, p < 0.001) engraftment were lower for PTCy-based. Day +100 cumulative incidences of grade II-IV and III-IV aGVHD, and 5-year CI of extensive cGVHD were 32%, 18% and 18% for PTCy-based and 25% (p = 0.3), 13% (p = 0.4) and 31% (p = 0.09) for the conventional cohort. Five-year OS (51% vs. 52%, p = 0.6) and GRFS (33% vs. 25%, p = 0.6) were similar between groups. Patients receiving PTCy had a trend to a lower cumulative incidence of relapse (20% vs. 33%, p = 0.06), not confirmed on multivariable analysis (p = 0.3). Although higher NRM rates were observed in patients receiving PTCy (32% vs. 21%, p = 0.02) on univariate analysis, this was not confirmed on multivariate analysis (HR 1.46, p = 0.18), and there was no resultant effect on OS (HR 1.20, p = 0.5). Based on these data, PTCy prophylaxis appears to be an attractive option for patients with MDS undergoing MSD allo-HCT.

Allogeneic Hematopoietic Cell Transplantation with Non-Myeloablative Conditioning and Post-Transplant Cyclophosphamide Prophylaxis in Patients with Reduced Systolic Function

Post-transplantation cyclophosphamide (PTCy) has become standard of care for graft-versus-host disease (GVHD) prophylaxis after allogeneic hematopoietic cell transplantation (alloHCT), allowing for expanded donor options. However, there is scant literature examining outcomes of patients with reduced systolic function receiving PTCy. The present study aimed to describe our experience in performing alloHCT in patients with reduced systolic function, including their nonrelapse mortality (NRM), overall survival (OS), and cumulative incidence of early cardiac events (ECEs). We performed a retrospective descriptive analysis using the Johns Hopkins Hematologic Malignancy database. From 2017 through 2021, 1118 consecutive patients underwent alloHCT with nonmyeloablative (NMA) conditioning and PTCy. Forty-three of those patients had a pretransplantation left ventricular ejection fraction (LVEF) ≤45% measured by transthoracic echocardiography. Patients whose LVEF improved on treatment prior to transplantation were also included. These 2 cohorts were stratified into 2 groups-heart failure with reduced ejection fraction (HFrEF) and heart failure with recovered ejection fraction (HFrecEF)-and subgroup analyses compared NRM, OS, and cumulative incidence of ECEs, including arrhythmia, coronary artery disease, reduction in LVEF, and pericardial effusion, within 100 days post-transplantation. The median LVEF was 40% to 45% (range, 30% to 45%) for the 31 patients undergoing transplantation with HFrEF and 35% to 40% (range, 20% to 45%) for the 12 patients with HFrecEF. The NRM for all 43 patients was 16% (95% confidence interval [CI], 5% to 27%) at 100 days and 23% (95% CI, 11% to 36%) at 2 years. The NRM was 23% (95% CI, 8% to 38%) at 100 days and 26% (95% CI, 10% to 42%) at 2 years for the HFrEF cohort and 0 at 100 days and 18% (95% CI, 0 to 41%) at 2 years for the HFrecEf cohort. The OS at 3 years was 41% (95% CI, 26% to 62%), 40% (95% CI, 25% to 65%) and 38% (95% CI, 14% to 100%) in the combined, HFrEF, and HFrecEF cohorts, respectively. The cumulative incidence of any ECE was 37.2% (95% CI, 22% to 51.9%), including 39% of HFrEF subjects and 33% of HFrecEF subjects. Grade ≥3 toxicities were seen in 56% of patients. Reduced ejection fraction was the most common ECE. One death was attributable to a cardiac etiology. Cardiac toxicities seemed to be more frequent and severe in patients with a history of systolic dysfunction, but this did not lead to worse survival outcomes. This study adds to and extends the existing literature supporting the use of NMA conditioning and PTCy in patients with systolic dysfunction.

Cardio-oncology and transplantation for acute myeloid leukemia

Despite the rapidly evolving treatment landscape for acute myeloid leukemia (AML), allogeneic hematopoietic cell transplantation (allo-HCT) remains an important and potentially curative treatment option for many high-risk AML patients. Cardiovascular disease is an important competing risk throughout allo-HCT and a key driver of morbidity and mortality long after treatment. Cardio-oncology is a new discipline in cardiology which provides multidisciplinary care and expertise to complex cancer patients with the aims of optimizing cardiovascular health plus monitoring and treating potential cardiotoxicity related to cancer treatments. As allogeneic HCT techniques get more sophisticated there will be an increase in transplant eligible older patients with a rise in comorbidities including established cardiovascular disease highlighting the need for close collaboration with cardio-oncology specialists from the time of diagnosis through late survivorship.

Comorbidities in transplant recipients with acute myeloid leukemia receiving low-intensity conditioning regimens: an ALWP EBMT study

Older age and a high burden of comorbidities often drive the selection of low-intensity conditioning regimens in allogeneic hematopoietic stem cell transplantation recipients. However, the impact of comorbidities in the low-intensity conditioning setting is unclear. We sought to determine the contribution of individual comorbidities and their cumulative burden on the risk of nonrelapse mortality (NRM) among patients receiving low-intensity regimens. In a retrospective analysis of adults (≥18 years) who underwent transplantation for acute myeloid leukemia in the first complete remission between 2008 and 2018, we studied recipients of low-intensity regimens as defined by the transplantation conditioning intensity (TCI) scale. Multivariable Cox models were constructed to study associations of comorbidities with NRM. Comorbidities identified as putative risk factors in the low-TCI setting were included in combined multivariable regression models assessed for overall survival, NRM, and relapse. A total of 1663 patients with a median age of 61 years received low-TCI regimens. Cardiac comorbidity (including arrhythmia/valvular disease) and psychiatric disease were associated with increased NRM risk (hazard ratio [HR], 1.54; 95% confidence interval [CI], 1.13-2.09 and HR, 1.69; 95% CI, 1.02-2.82, respectively). Moderate pulmonary dysfunction, though prevalent, was not associated with increased NRM. In a combined model, cardiac, psychiatric, renal, and inflammatory bowel diseases were independently associated with adverse transplantation outcomes. These findings may inform patient and regimen selection and reinforce the need for further investigation of cardioprotective transplantation approaches.

[Cardiac complications following allogeneic hematopoietic stem cell transplantation: Recommendations of the SFGM-TC]

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) can lead to early cardiac complications as well as late sequelae. A cardiac evaluation is essential in the pre-transplant assessment given the patient's comorbidities and previous chemotherapy treatments received. Various thresholds of cardiac function are recommended as eligibility criteria. The rise of haplo-identical transplantation with the use of post-transplant high-dose cyclophosphamide (PT-Cy) as a prophylaxis against graft-versus-host disease (GVHD) is accompanied by a resurgence of cardiological concerns. Arrhythmias are also a concern and the list of drugs implicated in this complication is growing. The rare occurrence of cardiac GVHD has been reported, although the entity is not well defined. Finally, although long-term follow-up recommendations exist, they are not accompanied by specific targets for cardiovascular risk factors, the presence of which is nevertheless increased after HSCT. In the framework of the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC) practice harmonization workshops held in Lille in September 2019, the prophylaxis, the diagnostic approach and the treatments of cardiac complication following HSCT were reviewed after analysis of published studies.

How I prevent GVHD in high-risk patients: posttransplant cyclophosphamide and beyond

Advances in conditioning, graft-versus-host disease (GVHD) prophylaxis and antimicrobial prophylaxis have improved the safety of allogeneic hematopoietic cell transplantation (HCT), leading to a substantial increase in the number of patients transplanted each year. This influx of patients along with progress in remission-inducing and posttransplant maintenance strategies for hematologic malignancies has led to new GVHD risk factors and high-risk groups: HLA-mismatched related (haplo) and unrelated (MMUD) donors; older recipient age; posttransplant maintenance; prior checkpoint inhibitor and autologous HCT exposure; and patients with benign hematologic disorders. Along with the changing transplant population, the field of HCT has dramatically shifted in the past decade because of the widespread adoption of posttransplantation cyclophosphamide (PTCy), which has increased the use of HLA-mismatched related donors to levels comparable to HLA-matched related donors. Its success has led investigators to explore PTCy's utility for HLA-matched HCT, where we predict it will be embraced as well. Additionally, combinations of promising new agents for GVHD prophylaxis such as abatacept and JAK inhibitors with PTCy inspire hope for an even safer transplant platform. Using 3 illustrative cases, we review our current approach to transplantation of patients at high risk of GVHD using our modern armamentarium.

Cardiac Toxicity after Matched Allogeneic Hematopoietic Cell Transplantation in the Post-Transplant Cyclophosphamide Era

Graft-versus-host-disease (GVHD) is one of the leading causes of non-relapse mortality (NRM) following allogeneic hematopoietic cell transplantation (alloHCT). Post-transplant cyclophosphamide (PTCy) has shown promise in managing GVHD. However, cyclophosphamide has known cardiac toxicities and few studies have evaluated the cardiac toxicities that arise following PTCy. Here, we completed a retrospective analysis of matched alloHCT patients at our institution who received PTCy or non-PTCy-based GVHD prophylaxis, with the goal of determining the incidence of cardiac toxicities up to 100 days after alloHCT. We included 585 patients in our analysis and found that 38 patients (6.5%) experienced cardiac toxicities after alloHCT. The toxicities observed included arrhythmias (n=21), heart failure (n=14), pericardial effusions (n=10), and myocardial infarction or ischemia (n=7). Patients who received PTCy had a 7.4% incidence of cardiac toxicities, while non-PTCy patients had an incidence of 5.8% (p=0.4). We found that age > 55 years (p=0.02), history of hypertension (p=0.01), arrhythmia (p=0.003), diabetes (p=0.04), and cardiac comorbidities (p<0.001) were significant predictors of cardiac toxicity, while none of the preparative and GVHD prophylaxis regimens used were predictive of cardiac toxicity. From these findings, we proposed the use of a Cardiac Risk Stratification Score to quantify the risk of cardiac toxicity following alloHCT and found that a higher score correlated with cardiac toxicity incidence. Furthermore, the development of cardiac toxicity was associated with worse 1-yr overall survival (OS) and NRM while the use of PTCy was associated with improvements in 1-year OS and NRM rates.

Serial Changes in Cardiac Strain and Contractility After Hematopoietic Stem Cell Transplantation in Patients with Hematologic Malignancies

Hematopoietic stem cell transplantation (HSCT) is occasionally associated with cardiac dysfunction during long-term follow-up. Global longitudinal strain (GLS) has emerged as an early predictor of cardiotoxicity associated with cancer therapy; however, the serial changes in GLS before and after HSCT have not been elucidated. To clarify the association between HSCT and GLS, we investigated serial changes in GLS before and after HSCT. We evaluated cardiac function before and 1, 3, and 6 months after HSCT in 38 consecutive HSCT patients enrolled in this study. Overall, GLS and left ventricular (LV) ejection fraction (EF) temporally decreased 1 month post-HSCT. LVEF completely recovered to baseline at 3 months after HSCT, whereas GLS partially recovered 6 months after HSCT. Except for five patients who died within 6 months, GLS values in the low EF group (LVEF ≤ 55% at 6 months post-HSCT, n = 6) were significantly and consistently lower than those in the normal EF group (LVEF > 55% at 6 months post-HSCT, n = 27) at any time during follow-up. These findings suggest that GLS before HSCT might be associated with a decrease in LVEF after HSCT in patients with hematologic malignancies. Further prospective and long-term data will be important for understanding the management of HSCT-associated cardiac dysfunction.

Cardiovascular disease and its management in children and adults undergoing hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for many malignancies, hemoglobinopathies, metabolic diseases, bone marrow failure syndromes, and primary immune deficiencies. Despite the significant improvement in survival afforded by HSCT, the therapy is associated with major short and long-term morbidity and mortality. Cardiovascular complications such as cardiomyopathy, arrhythmias, pulmonary hypertension, and pericardial effusions are increasingly recognized as potential outcomes following HSCT. The incidence of cardiac complications is related to various factors such as age, co-morbid medical conditions, whether patients received cardiotoxic chemotherapy prior to HSCT, the type of HSCT (autologous versus allogeneic), and the specific conditioning regimen. Thus, the cardiovascular evaluation has become a core component of the pre-transplant assessment, however, the practice differs from center to center as national guidelines and contemporary high-quality studies are lacking. We review the incidence of cardiotoxicity in pediatric and adult HSCT, potential mechanisms of injury, and effects on long-term outcomes. We also discuss the possible therapeutic approaches when disease arises, as well as the indications and need for surveillance before, during, and after transplantation.

Multicenter Phase II Study on Haploidentical Bone Marrow Transplantation Using a Reduced-Intensity Conditioning Regimen and Posttransplantation Cyclophosphamide in Patients with Poor-Prognosis Lymphomas

Allogeneic stem cell transplantation from haploidentical donors using unmanipulated bone marrow and posttransplantation cyclophosphamide has been largely employed to cure high-risk lymphomas. However, the increased incidence of relapse associated with the use of a nonmyeloablative conditioning regimen is still considered a concerning issue. The aim of our study was to prospectively evaluate the efficacy and feasibility of a reduced-intensity conditioning regimen, including thiotepa, cyclophosphamide, and fludarabine, in high-risk lymphoma patients. This was a prospective multicenter study. We enrolled 49 patients, of whom 47 were evaluable. Graft source (bone marrow) and graft-versus-host disease (GVHD) prophylaxis were the same for all patients. The primary endpoint was the proportion of patients free of disease progression at 1 year. The primary endpoint was met, as 29 out of 47 patients were alive and free of disease at 1 year (1-year progression-free survival, 60%). Forty-five recipients engrafted and achieved full donor chimerism at day 100. The cumulative incidences (CIs) of ANC engraftment at 30 days and platelet engraftment at 60 days were 89% and 83%, respectively. Two patients experienced graft failure. The CIs of day 100 grades 2 to 4 acute GVHD and 2-year moderate-to-severe chronic GVHD were 26% and 16%, respectively. With a median follow-up of 47.5 months (range, 22 to 74), the 4-year progression-free survival and overall survival were 54% and 64%, respectively. The 4-year CI of relapse was 28%, and the 4-year nonrelapse mortality was 15%. Thiotepa-based reduced-intensity conditioning was well tolerated with encouraging survival in a cohort of patients with poor-prognosis lymphoma. Both the incidence of relapse and nonrelapse mortality were acceptable.

Clinical prevalence and outcome of cardiovascular events in the first 100 days postallogeneic hematopoietic stem cell transplant

INTRODUCTION

Recent advances in allogeneic hematopoietic stem cell transplant (HSCT) have allowed us to offer HSCT to older, advanced disease patients with more co-morbidities. Cardiovascular toxicity post-transplant is a major concern due to the increased risk of mortality. Few studies have examined the prevalence of CV events including CAD (MI, angina, PCI, CABG, CHF, arrhythmias), HTN, stroke/TIA, and death in the first 100 days post-transplant.

PATIENTS

We assessed the impact of pretransplant MUGA results in predicting postallogeneic HSCT CV events and overall survival in the first 100 days, and whether or not transient anthracycline-induced cardiomyopathy or cumulative anthracycline dose affected overall survival. This retrospective, cohort study included 665 patients with a median age of 52 years who underwent HSCT from 2009 to 2015.

RESULTS

The most frequent CV event in the first 100 days post-HSCT was arrhythmia seen in 2.9% of patients followed up by CHF (12.3%), MI (9%), and angina (8%). Two patients had PCI, and both survived the first 100 days. Cardiovascular risk factors predict for a poor MUGA scan but not survival. Higher dose anthracycline pretransplant predicted for a poor outcome.

CONCLUSION

A history of CV disease, MI, or CAD was the most important predictive of CV events, P-value = .00002. 88.6% survived the first 100 days. Patients with an EF < 50% had a significant likelihood of having a CV event compared to patients with an EF > 60% (OR = 5.3, 95% CI [1.6-18.1], P = .0219). Cumulative anthracycline dose did not have a significant impact on overall survival.

HLA-haploidentical stem cell transplantation using posttransplant cyclophosphamide

HLA-haploidentical stem cell transplantation using posttransplant cyclophosphamide has spread rapidly worldwide. This strategy was initially developed in the setting of bone marrow transplantation following nonmyeloablative conditioning. Recently, peripheral blood stem cell grafts and/or myeloablative conditioning regimen have been widely used. In Japan, prospective, multicenter, phase II studies have been conducted by the Japan Study Group for Cell Therapy and Transplantation to evaluate the safety and efficacy of HLA-haploidentical peripheral blood stem cell transplantation using posttransplant cyclophosphamide (PTCy-haploPBSCT). In the first such study (JSCT Haplo 13 study), we demonstrated that PTCy-haploPBSCT after busulfan-based reduced-intensity conditioning (RIC) enables stable donor engraftment and low incidences of both acute and chronic graft-versus-host disease (GVHD). In the second (JSCT Haplo 14 study), we showed that both myeloablative conditioning (MAC) and RIC are valid options for PTCy-haploPBSCT. Emerging evidence, including our findings, suggests that donor type (HLA-haploidentical donor versus HLA-matched related or unrelated donor) may no longer be a significant predictor of transplant outcome.

Haploidentical hematopoietic cell transplantation for adult acute myeloid leukemia: a position statement from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Allogeneic blood or marrow hematopoietic cell transplantation continues to be the most potent anti-leukemic treatment for adult patients with standard, high-risk, or chemo-refractory acute myeloid leukemia. Until recently, this procedure was generally limited to those recipients who had an available matched-sibling donor or matched-unrelated donor. Technical advances in graft cell processing and manipulation, control of bidirectional T cell alloreactivity, graft-versus-host disease prophylaxis, and other supportive measures in haploidentical transplantation now enable nearly all patients with acute myeloid leukemia to benefit from the graft-versus-leukemia effect with substantial reduction in procedure-related mortality. Over recent years, haploidentical donors have been increasingly adopted as a valid donor source in allogeneic hematopoietic cell transplantation for acute myeloid leukemia in the absence of an HLA-matched donor. Among centers of the European Society for Blood and Marrow Transplantation, the use of haploidentical related donor transplantation has increased by 250% since 2010, and 291% since 2005. On behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize recent utilization trends in haploidentical transplantation for acute myeloid leukemia and describe the transformative changes in haploidentical hematopoietic cell transplantation techniques over the past decade, which have led to the current widespread use of this procedure. Furthermore, we review the efficacy of haploidentical hematopoietic cell transplantation for acute myeloid leukemia from available studies, including preliminary comparative studies, and bring attention to remaining unanswered questions and directions for future research. We conclude this report with our recommendations for the role of haploidentical hematopoietic cell transplantation in acute myeloid leukemia.