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Abstract Background Nephrotic syndrome (NS) is a rare complication that can occur after haematopoietic stem cell transplantation (HSCT). In patients with membranous nephropathy (MN) who have undergone allogeneic HSCT, a new antigen called protocadherin FAT1 has been identified. Our objective is to present a case series of MN patients after HSCT with a novel antigen-based stratification. Case presentations Patients who developed full-blown NS due to MN after an HSCT were enrolled in the University Hospital Centre Zagreb study. The first two patients were treated with an HSCT for acute myeloid leukaemia, and both developed NS after cessation of graft versus host disease (GVHD) prophylaxis. The first patient had reduced kidney function, while the second had completely preserved function. Kidney biopsy showed MN with only subepithelial deposits. A thorough examination revealed that there was no secondary cause of the disease. The patients achieved complete remission after undergoing immunosuppression treatment. The third patient underwent HSCT for acute lymphoblastic leukaemia. He developed both acute and chronic GVHD and also experienced avascular hip necrosis. After sixteen years, the patient developed NS with preserved kidney function. The kidney specimen showed membranous nephropathy (MN) with mesangial and subepithelial deposits. Extensive research was conducted, but no secondary cause for the MN was detected. All three cases tested negative for anti-PLA2R antibodies. Biopsy tissue samples were analysed using laser microdissection and tandem mass spectrometry of glomeruli for the detection of different specific antigens. Patients one and two tested positive for FAT1, whereas patient three tested positive for PCSK6. Conclusions MN can develop at various time intervals after HSCT. Specific antigen testing can help establish the relationship between MN and HSCT. In the future, serum testing for anti-FAT1 antibodies in HSCT patients could be significant in diagnosing FAT1-associated MN, similar to how anti-PLA2R antibodies are significant in diagnosing PLA2R-associated MN.

BackgroundGraft-versus-host disease (GVHD) is the major cause of short- and long-term morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Treatment options beyond corticosteroid therapy remain limited, and prolonged treatment often leads to impaired quality of life (QoL). A better understanding of the needs and experiences of patients with GVHD is required to improve patient care. ObjectiveThe aim of this study is to explore different social media (SM) channels for gathering and analyzing the needs and experiences of patients and other stakeholders across 14 European countries. MethodsWe conducted a retrospective analysis of SM data from the public domain. The Talkwalker social analytics tool collected data from open-access forums, blogs, and various social networking sites using predefined search strings. The raw data set derived from the aggregator tool was automatically screened for the relevancy of posts, generating the curated data set that was manually reviewed to identify posts that fell within the predefined inclusion and exclusion criteria. This final data set was then used for the deep-dive analysis. ResultsA total of 9016 posts relating to GVHD were identified between April 2019 and April 2021. Deduplication and relevancy checks resulted in 325 insightful posts, with Twitter contributing 250 (77%) posts; blogs, 49 (15%) posts; forums, 13 (4%) posts; Facebook, 7 (2%) posts; and Instagram and YouTube, 4 (1%) posts. Patients with GVHD were the primary stakeholders, contributing 63% of all SM posts. In 234 posts, treatment was the most discussed stage of the patient journey (68%), followed by symptoms (33%), and diagnosis and tests (21%). Among treatment-related posts (n=159), steroid therapy was most frequently reported (54/159, 34%). Posts relating to treatment features (n=110) identified efficacy (45/110, 41%), side effects (38/110, 35%), and frequency and dosage (32/110, 29%), as the most frequently discussed features. Symptoms associated with GVHD were described in 24% (77/325) of posts, including skin-related conditions (49/77, 64%), dry eyes or vision change (13/77, 17%), pain and cramps (16/77, 21%), and fatigue or muscle weakness (12/77, 16%). The impacts of GVHD on QoL were discussed in 51% (165/325) of all posts, with the emotional, physical and functional, social, and financial impacts mentioned in 69% (114/165), 50% (82/165), 5% (8/165), and 2% (3/165) of these posts, respectively. Unmet needs were reported by patients or caregivers in 24% (77/325) of analyzed conversations, with treatment-related side effects being the most common (35/77, 45%) among these posts. ConclusionsSM listening is a useful tool to identify medical needs. Treatment of GVHD, including treatment-related side effects, as well as its emotional and physical impact on QoL, are the major topics that GVHD stakeholders mention on SM. We encourage a structured discussion of these topics in interactions between health care providers and patients with GVHD. Trial RegistrationNot applicable

Abstract Background Assessment of measurable residual disease (MRD) is rapidly transforming the therapeutic and prognostic landscape of a wide range of hematological malignancies. Its prognostic value in acute lymphoblastic leukemia (ALL) has been established and MRD measured at the end of induction is increasingly used to guide further therapy. Although MRD detectable immediately before allogeneic hematopoietic cell transplantation (HCT) is known to be associated with poor outcomes, it is unclear if or to what extent this differs with different types of conditioning. Methods In this retrospective registry study, we explored whether measurable residual disease (MRD) before allogeneic hematopoietic cell transplantation (HCT) for acute lymphoblastic leukemia is associated with different outcomes in recipients of myeloablative total body irradiation (TBI)-based versus chemotherapy-based conditioning. We analyzed outcomes of 2780 patients (median age 38 years, range 18–72) who underwent first HCT in complete remission between 2000 and 2017 using sibling or unrelated donors. Results In 1816 of patients, no disease was detectable, and in 964 patients, MRD was positive. Conditioning was TBI-based in 2122 (76%) transplants. In the whole cohort MRD positivity was a significant independent factor for lower overall survival (OS) and leukemia-free survival (LFS), and for higher relapse incidence (RI), with respective hazard ratios (HR, 95% confidence intervals) of 1.19 (1.02–1.39), 1.26 (1.1–1.44), and 1.51 (1.26–1.8). TBI was associated with a higher OS, LFS, and lower RI with HR of 0.75 (0.62–0.90), 0.70 (0.60–0.82), and 0.60 (0.49–0.74), respectively. No significant interaction was found between MRD status and conditioning. When investigating the impact of MRD separately in the TBI and chemotherapy-based conditioning cohorts by multivariate analysis, we found MRD positivity to be associated with lower OS and LFS and higher RI in the TBI group, and with higher RI in the chemotherapy group. TBI-based conditioning was associated with improved outcomes in both MRD-negative and MRD-positive patients. Conclusions In this large study, we confirmed that patients who are MRD-negative prior to HCT achieve superior outcomes. This is particularly apparent if TBI conditioning is used. All patients with ALL irrespective of MRD status benefit from TBI-based conditioning in the myeloablative setting.

Disease- and treatment-mediated immunodeficiency might render SARS-CoV-2 vaccines less effective in patients with hematologic diseases. We performed a prospective non-interventional study to evaluate humoral response after one and two doses of mRNA-1273, BNT162b2, or ChAdOx1 nCoV-19 vaccine in 118 patients with different malignant or non-malignant hematologic diseases from three Croatian treatment centers. An electrochemiluminescent assay was used to measure total anti-SARS-CoV-2 S-RBD antibody titers. After one vaccine dose, 20/66 (33%) achieved seropositivity with a median antibody titer of 6.1 U/mL. The response rate (58/90, 64.4%) and median antibody titer (>250 U/mL) were higher after two doses. Seropositivity varied with diagnosis (overall p < 0.001), with the lowest rates in lymphoma (34.6%) and chronic lymphocytic leukemia (52.5%). The overall response rate in chronic myeloproliferative neoplasms (CMPN) was 81.3% but reached 100% in chronic myeloid leukemia and other non-myelofibrosis CMPN. At univariable analysis, age > 67 years, non-Hodgkin’s lymphoma, active treatment, and anti-CD20 monoclonal antibody therapy increased the likelihood of no vaccine response, while hematopoietic stem cell recipients were more likely to respond. Age and anti-CD20 monoclonal antibody therapy remained associated with no response in a multivariable model. Patients with the hematologic disease have attenuated responses to SARS-CoV-2 vaccines, and significant variations in different disease subgroups warrant an individualized approach.

Rituximab (R) is increasingly incorporated in reduced intensity conditioning (RIC) regimens for allogeneic hematopoietic cell transplantation (alloHCT) in patients with B-cell malignancies, not only to improve disease control, but also to prevent graft-versus-host disease (GVHD). There are no randomized prospective data to validate this practice, although single center data and the CIBMTR analysis have shown promising results. We aimed at validation of these findings in a large registry study. We conducted a retrospective analysis using the EBMT registry of 3,803 adult patients with B-cell malignancies undergoing alloHCT (2001–2013) with either rituximab (R-RIC-9%) or non-rituximab (RIC-91%) reduced intensity regimens respectively. Median age and median follow up were 55 years (range 19.1–77.3) and 43.2 months (range 0.3–179.8), respectively. There was no difference in transplant outcomes (R-RIC vs RIC), including 1-year overall survival (69.9% vs 70.7%), 1-year disease-free survival (64.4% vs 62.2%), 1-year non-relapse mortality (21% vs 22%), and day-100 incidence of acute GVHD 2-4° (12% vs 12%). In summary, we found that addition of rituximab in RIC regimens for B-cell malignancies had no significant impact on major transplant outcome variables. Of note, data on chronic GVHD was not available, limiting the conclusions that can be drawn from the present study.

Abstract There is an increased risk of GVHD and of non-relapse mortality (NRM) after allogeneic stem cell transplantations (alloSCT) when mismatched unrelated donors (MMUD) are used. In Europe, it is standard practice to use rabbit anti-thymocyte globulin (rATG) to reduce the high NRM and GVHD risks after MMUD alloSCT. As an alternative to rATG, post-transplantation Cyclophosphamide (PTCy) is in increasing clinical use. It is currently impossible to give general recommendations regarding preference for one method over another since comparative evidence from larger data sets is lacking. To improve the evidence base, we analyzed the outcome of rATG vs. PTCy prophylaxis in adult patients with hematologic malignancies undergoing first peripheral blood alloSCT from MMUD (9/10 antigen match) between Jan 2018 and June 2021 in the database of the European Society for Blood and Marrow Transplantation (EBMT). We performed multivariate analyses using the Cox proportional-hazards regression model. We included 2123 patients in the final analyses (PTCy, n = 583; rATG, n = 1540). p values and hazard ratios (HR) presented here are multivariate outcomes. Two years after alloSCT we found a lower NRM in the PTCy group of 18% vs. 24.9% in the rATG group; p = 0.028, HR 0.74. Overall survival in the PTCy cohort was higher with 65.7% vs. 55.7% in the rATG cohort; p

CAR-T cells are in standard clinical use to treat relapsed or refractory hematologic malignancies, such as non-Hodgkin’s lymphoma, multiple myeloma and acute lymphoblastic leukemia. Owing to the rapidly progressing field of CAR-T cell therapy and the lack of generally accepted treatment guidelines, we hypothesized significant differences between European centers in prevention, diagnosis and management of short- and long-term complications. To capture the current CAR-T cell management among EBMT centers and to determine the medical need and specific areas for future clinical research the EBMT Transplant Complications Working Party performed a survey among 227 EBMT CAR-T cell centers. We received complete servey answers from 106 centers (47%) addressing questions in the areas of product selection, CAR-T cell logistics, management of cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome as well as management in later phases including prolonged cytopenias. We identified common patterns in complication management, but also significant variety in clinical management of the centers in important aspects. Our results demonstrate a high medical need for treatment harmonization and future clinical research in the following areas: treatment of steroid-refractory and very severe CRS/neurotoxicity, treatment of cytopenia, early discharge and outpatient management, as well as immunoglobulin substitution.

Background We previously reported that the “Endothelial Activation and Stress Index” (EASIX; ((creatinine×lactate dehydrogenase)÷thrombocytes)) measured before start of conditioning predicts mortality after allogeneic hematopoietic stem cell transplantation (alloSCT) when used as continuous score. For broad clinical implementation, a prospectively validated EASIX-pre cut-off is needed that defines a high-risk cohort and is easy to use.Method In the current study, we first performed a retrospective cohort analysis in n=2022 alloSCT recipients and identified an optimal cut-off for predicting non-relapse mortality (NRM) as EASIX-pre=3. For cut-off validation, we conducted a multicenter prospective study with inclusion of n=317 first alloSCTs from peripheral blood stem cell in adult patients with acute leukemia, lymphoma or myelodysplastic syndrome/myeloproliferative neoplasms in the European Society for Blood and Marrow Transplantation network.Results Twenty-three % (n=74) of alloSCT recipients had EASIX-pre ≥3 taken before conditioning. NRM at 2 years was 31.1% in the high EASIX group versus 11.5% in the low EASIX group (p

IntroductionExtracorporal Photophoresis (ECP) is in clinical use for steroid-refractory and steroid-dependent acute GVHD (SR-aGVHD). Based on recent Phase-III study results, ruxolitinib has become the new standard of care for SR-aGVHD. Our aim was to collect comparative data between ruxolitinib and ECP in SR-aGVHD in order to improve the evidence base for clinical decision making. MethodsWe asked EBMT centers if they were willing to participate in this study by completing a data form (Med-C) with detailed information on GVHD grading, -therapy, -dosing, -response and complications for each included patient.Results31 centers responded positively (14%) and we included all patients receiving alloSCT between 1/2017-7/2019 and treated with ECP or ruxolitinib for SR-aGVHD grades II-IV from these centers. We identified 53 and 40 patients with grades II-IV SR-aGVHD who were treated with ECP and ruxolitinib, respectively. We performed multivariate analyses adjusted on grading and type of SR-aGVHD (steroid dependent vs. refractory). At day+90 after initiation of treatment for SR-aGVHD we found no statistically significant differences in overall response. The odds ratio in the ruxolitinib group to achieve overall response vs. the ECP group was 1.13 (95% CI = [0.41; 3.22], p = 0.81). In line, we detected no statistically significant differences in overall survival, progression-free survival, non-relapse mortality and relapse incidence.DiscussionThe clinical significance is limited by the retrospective study design and the current data can’t replace prospective studies on ECP in SR-aGVHD. However, the present results contribute to the accumulating evidence on ECP as an effective treatment option in SR-aGVHD.

We investigated ≥ grade 3 (CTC-AE) organ toxicities for commercial CD19 chimeric antigen receptor T cell (CAR-T cell) products in 492 patients (Axi-Cel; n = 315; Tisa-Cel; n = 177) with Large B-cell Lymphoma in the European Society for Blood and Marrow Transplantation (EBMT) CAR-T registry. The incidence of ≥ grade 3 organ toxicities during the first 100 days after CAR-T was low and the most frequent were: renal (3.0%), cardiac (2.3%), gastro-intestinal (2.3%) and hepatic (1.8%). The majority occurred within three weeks after CAR-T cell therapy. Overall survival was 83.1% [79.8-86.5; 95% CI] at 3 months and 53.5% [49-58.4; 95% CI] at one year after CAR-T. The most frequent cause of death was tumour progression (85.1%). Non-relapse mortality was 3.1% [2.3-4.1; 95% CI] at 3 months and 5.2% [4.1-6.5; 95% CI] at one year after CAR-T. The most frequent causes of non-relapse mortality were cell-therapy-related toxicities including organ toxicities (6.4% of total deaths) and infections (4.4% of total deaths). Our data demonstrates good safety in the European real-world setting.

We investigated the incidence and outcome of anti-CD19 chimeric antigen receptor (CAR) T-cells-associated Common Terminology Criteria for Adverse Events (CTCAE) ≥grade 3 cytopenia. In the EBMT CAR-T registry, we identified 398 adult patients with large B-cell lymphoma who had been treated with CAR-T-cells with axicel (62%) or tisacel (38%) before August 2021 and had cytopenia status documented for the first 100 days. Most patients had received two or three previous lines of therapy, however, 22.3% had received four or more. Disease status was progressive in 80.4%, stable in 5.0% and partial/complete remission in 14.6%. 25.9% of the patients had received a transplantation before. Median age was 61.4 years (min–max; IQR=18.7–81; (52.9–69.5)).The cumulative incidence of ≥grade 3 cytopenia was 9.0% at 30 days (95% CI (6.5 to 12.1)) and 12.1% at 100 days after CAR T-cell infusion (95% CI (9.1 to 15.5)). The median time from CAR-T infusion to cytopenia onset was 16.5 days (min–max; IQR=1–90; (4–29.8)). Grade 3 and grade 4 CTCAE cytopenia occurred in 15.2% and 84.8%, respectively. In 47.6% there was no resolution.Severe cytopenia had no significant impact on overall survival (OS) (HR 1.13 (95% CI 0.74 to 1.73), p=0.57). However, patients with severe cytopenia had a poorer progression-free survival (PFS) (HR 1.54 (95% CI 1.07 to 2.22), p=0.02) and a higher relapse incidence (HR 1.52 (95% CI 1.04 to 2.23), p=0.03). In those patients who developed severe cytopenia during the first 100 days (n=47), OS, PFS, relapse incidence and non-relapse mortality at 12 months after diagnosis of severe cytopenia were 53.6% (95% CI (40.3 to 71.2)), 20% (95% CI (10.4 to 38.6)), 73.5% (95% CI (55.2 to 85.2)) and 6.5% (95% CI (1.7 to 16.2)), respectively.In multivariate analysis of severe cytopenia risk factors, only year of CAR-T infusion (HR=0.61, 95% CI (0.39 to 0.95), p=0.028) and total number of treatment lines before CAR-T infusion (one or two lines vs three or more, HR=0.41, 95% CI (0.21 to 0.83), p=0.013) had a significant positive association with the incidence of cytopenia. Other factors, such as previous transplantation, disease status at time of CAR-T, patient age and patient sex, had no significant association.Our data provide insight on frequency and clinical relevance of severe cytopenia after CAR T-cell therapy in the European real-world setting.

Graft versus host disease (GVHD) prophylaxis with posttransplantation cyclophosphamide (PTCY) has been established to reduce severe GVHD, and thereby potentially reducing nonrelapse mortality (NRM) after allogeneic stem cell transplantation (alloSCT). We evaluated the predictive capacity of established NRM-risk scores in patients receiving PTCY-based GVHD prophylaxis, and subsequently developed and validated a novel PTCY-specific NRM-risk model. Adult patients (n = 1861) with AML or ALL in first complete remission who received alloSCT with PTCY-based GVHD prophylaxis were included. The PTCY-risk score was developed using multivariable Fine and Gray regression, selecting parameters from the hematopoietic cell transplantation-comorbidity index (HCT-CI) and European Group for Blood and Marrow Transplantation (EBMT) score with a subdistribution hazard ratio (SHR) of ≥1.2 for 2-year NRM in the training set (70% split), which was validated in the test set (30%). The performance of the EBMT score, HCT-CI, and integrated EBMT score was relatively poor for discriminating 2-year NRM (c-statistic 51.7%, 56.6%, and 59.2%, respectively). The PTCY-risk score included 10 variables which were collapsed in 3 risk groups estimating 2-year NRM of 11% ± 2%, 19% ± 2%, and 36% ± 3% (training set, c-statistic 64%), and 11% ± 2%, 18% ± 3%, and 31% ± 5% (test set, c-statistic 63%), which also translated into different overall survival. Collectively, we developed an NRM-risk score for acute leukemia patients receiving PTCY that better predicted 2-year NRM compared with existing models, which might be applicable to the specific toxicities of high-dose cyclophosphamide.

In this registry-based study, we compared outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) in adult patients with acute lymphoblastic leukemia (ALL) transplanted in first complete remission (CR-1), following conditioning with total body irradiation (TBI) at a standard 12-Gray or at a lower 8-Gray total dose. Patients received fludarabine (flu) as the sole chemotherapy complementing TBI. Eight-Gray TBI/flu was used in 494 patients and 12-Gray TBI/flu in 145 patients. Eighty-eight (23.1%) and 36 (29%) of the patients had Ph-negative B-ALL, 222 (58.3%) and 53 (42.7%) had Ph-positive B-ALL, 71 (18.6%) and 35 (28.2%) T-ALL, respectively (P = 0.008). Patients treated with 8-Gray were older than ones received 12-Gray (median 55.7 versus 40.3 years, P < 0.0001) and were more frequently administered in vivo T-cell depletion (71% versus 40%, P

Acute graft-versus-host disease (aGvHD) remains a major threat to successful outcome following allogeneic hematopoietic cell transplantation though advances in prophylaxis and supportive care have been made. The aim of this study is to test whether the incidence and mortality of aGvHD have decreased over time. 102,557 patients with a median age of 47.6 years and with malignancies after first allogeneic sibling or unrelated donor (URD) transplant were studied in the following periods: 1990-1995, 1996-2000, 2001-2005, 2006-2010 and 2011-2015. Findings: 100-day incidences of aGvHD grades II-IV decreased from 40% to 38%, 32%, 29% and 28%, respectively, over calendar time (P

Despite its involvement in various immune functions, including the allogeneic activation of T-lymphocytes, the relevance of calcium (Ca2+) for GVHD pathobiology is largely unknown. To elucidate a potential association between Ca2+and GVHD, we analyzed Ca2+-sensing G-protein coupled receptor 6a (GPRC6a) signaling in preclinical GVHD models and conducted a prospective EBMT study on Ca2+ serum levels prior alloSCT including 363 matched sibling allogeneic peripheral blood stem cell transplantations (alloSCTs). In experimental models, we found decreased Gprc6a expression during intestinal GVHD. GPRC6a deficient alloSCT recipients had higher clinical and histopathological GVHD scores leading to increased mortality. As possible underlying mechanism, we found increased antigen presentation potential in GPRC6a–/– alloSCT recipients demonstrated by higher proliferation rates of T-lymphocytes. In patients with low Ca2+ serum levels (≤median 2.2 mmol/l) before alloSCT, we found a higher incidence of acute GVHD grades II-IV (HR = 2.3 Cl = 1.45–3.85 p = 0.0006), severe acute GVHD grades III-IV (HR = 3.3 CI = 1.59–7.14, p = 0.002) and extensive chronic GVHD (HR = 2.0 Cl = 1.04–3.85 p = 0.04). In conclusion, experimental and clinical data suggest an association of reduced Ca2+ signaling with increased severity of GVHD. Future areas of interest include the in depth analysis of involved molecular pathways and the investigation of Ca2+ signaling as a therapeutic target during GVHD.

The FMS-like tyrosine kinase 3 (FLT3) gene is mutated in 25-30% of patients with acute myeloid leukemia (AML). Because of the poor prognosis associated with FLT3-internal tandem duplication mutated AML, allogeneic hematopoietic stem-cell transplantation (SCT) was commonly performed in first complete remission. Remarkable progress has been made in frontline treatments with the incorporation of FLT3 inhibitors and the development of highly sensitive minimal/measurable residual disease assays. Similarly, recent progress in allogeneic hematopoietic SCT includes improvement of transplant techniques, the use of haploidentical donors in patients lacking an HLA matched donor, and the introduction of FLT3 inhibitors as post-transplant maintenance therapy. Nevertheless, current transplant strategies vary between centers and differ in terms of transplant indications based on the internal tandem duplication allelic ratio and concomitant nucleophos-min-1 mutation, as well as in terms of post-transplant maintenance/consolidation. This review generated by international leukemia or transplant experts, mostly from the European Society for Blood and Marrow Transplantation, attempts to develop a position statement on best approaches for allogeneic hematopoietic SCT for AML with FLT3-internal tandem duplication including indications for and modalities of such transplants and on the potential optimization of post-transplant maintenance with FLT inhibitors.

Graft-versus-host disease (GVHD) prophylaxis for unmanipulated haploidentical hematopoietic cell transplantation (haplo-HCT) include post-transplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG). Utilizing EBMT registry, we compared ATG versus PTCy based GVHD prophylaxis in adult acute lymphoblastic leukemia (ALL) patients undergoing haplo-HCT. Included were 434 patients; ATG (n=98) and PTCy (n=336). Median follow-up was ~2 years. Baseline characteristics were similar between the groups except that the ATG-group was more likely to have relapsed/refractory ALL (P=0.008), non-TBI conditioning (P

Introduction: Secondary haemophagocytic lymphohistiocytosis (sHLH) or Macrophage Activation Syndrome (MAS) is a life-threatening hyperinflammatory syndrome that can occur in patients with severe infections, malignancy or autoimmune diseases. It is also a rare complication of haematopoetic stem cell transplantation (HSCT), with a high mortality. It may be associated with graft vs. host disease in the allogeneic HSCT setting. It is also reported following CAR-T cell therapy, but differentiation from cytokine release syndrome (CRS) is challenging. Here, we summarise the literature and present results of a survey of current awareness and practice in EBMT-affiliated centres of sHLH/MAS following HSCT and CAR-T cell therapy.Methods: An online questionnaire was sent to the principal investigators of all EBMT member transplant centres treating adult patients (18 years and over) inviting them to provide information regarding: number of cases of sHLH/MAS seen in their centre over 3 years (2016–2018 inclusive); screening strategies and use of existing diagnostic/classification criteria and treatment protocols.Results: 114/472 centres from 24 different countries responded (24%). We report estimated rates of sHLH/MAS of 1.09% (95% CI = 0.89–1.30) following allogeneic HSCT, 0.15% (95% CI = 0.09–5.89) following autologous HSCT and 3.48% (95% CI = 0.95–6.01) following CAR-T cell therapy. A majority of centres (70%) did not use a standard screening protocol. Serum ferritin was the most commonly used screening marker at 78% of centres, followed by soluble IL-2 receptor (24%), triglycerides (15%), and fibrinogen (11%). There was significant variation in definition of “clinically significant” serum ferritin levels ranging from 500 to 10,000 μg/mL. The most commonly used criteria to support diagnosis were HLH-2004 (43%) and the H score (15%). Eighty percent of responders reported using no standard management protocol, but reported using combinations of corticosteroids, chemotherapeutic agents, cytokine blockade, and monoclonal antibodies.Conclusions: There is a remarkable lack of consistency between EBMT centres in the approach to screening, diagnosis and management. Further research in this field is needed to raise awareness of and inform harmonised, evidence-based approaches to the recognition and treatment of sHLH/MAS following HSCT/CAR-T cell therapy.