Advancements in Personalized CAR-T Therapy: Comprehensive Overview of Biomarkers and Therapeutic Targets in Hematological Malignancies.

Chimeric antigen receptor T-cell (CAR-T) therapy is a novel anticancer therapy using autologous or allogeneic T-cells. To date, six CAR-T therapies for specific B-cell acute lymphoblastic leukemia (B-ALL), non-Hodgkin lymphomas (NHL), and multiple myeloma (MM) have been approved by the Food and Drug Administration (FDA). Significant barriers to the effectiveness of CAR-T therapy include cytokine release syndrome (CRS), neurotoxicity in the case of Allogeneic Stem Cell Transplantation (Allo-SCT) graft-versus-host-disease (GVHD), antigen escape, modest antitumor activity, restricted trafficking, limited persistence, the immunosuppressive microenvironment, and senescence and exhaustion of CAR-Ts. Furthermore, cancer drug resistance remains a major problem in clinical practice. CAR-T therapy, in combination with checkpoint blockades and bispecific T-cell engagers (BiTEs) or other drugs, appears to be an appealing anticancer strategy. Many of these agents have shown impressive results, combining efficacy with tolerability. Biomarkers like extracellular vesicles (EVs), cell-free DNA (cfDNA), circulating tumor (ctDNA) and miRNAs may play an important role in toxicity, relapse assessment, and efficacy prediction, and can be implicated in clinical applications of CAR-T therapy and in establishing safe and efficacious personalized medicine. However, further research is required to fully comprehend the particular side effects of immunomodulation, to ascertain the best order and combination of this medication with conventional chemotherapy and targeted therapies, and to find reliable predictive biomarkers.

Response to anti-SARS-CoV-2 mRNA vaccines in multiple myeloma and chronic lymphocytic leukemia patients.

Multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) patients have increased morbidity and mortality rates of COVID-19 due to immunosuppression associated with the disease and ongoing therapy. The same immune impairment accompanying CLL and MM also affects suboptimal vaccine response. The study assessed the effectiveness of the humoral and T cell-mediated immunity following mRNA COVID-19 vaccination (using either BNT162b2 or mRNA-1273) in short-term (2-5 weeks after second dose) and long-term follow-up (12 weeks after vaccination). Between March and August 2021, blood samples were obtained from 62 CLL and 60 MM patients from eight different hematology departments in Poland. Total anti-RBD antibodies were detected in 37% MM patients before vaccination, increased to 91% and 94% in short- and long-term follow-up, respectively. In CLL, serological responses were detectable in 21% of patients before vaccination and increased to 45% in the short-term and 71% in long-term observation. We detected a tendency to higher frequencies of specific CD8+ T cells against SARS-CoV-2 after vaccination compared to samples before vaccination in MM patients and no changes in frequencies of specific T cells in CLL patients. Our study provides novel insights into mRNA vaccination efficacy in immunocompromised MM and CLL patients, and our findings highlight that specific CD8+ T cells against SARS-CoV-2 might be induced by vaccination but do not correlate positively with serological responses.

Rheumatological manifestations of chronic graft versus host disease - Case series.

OBJECTIVES: To present the rheumatological manifestations of chronic graft versus host disease (cGVHD) and describe how they differ from primary systemic connective tissue diseases. METHODS: Description of 7 patients with cGVHD with symptoms resembling Sjögren's syndrome and scleroderma, with a critical review of the literature. RESULTS: 7 patients treated at the hematology department, who developed cGVHD with present antinuclear antibodies, were referred to the rheumatology department for further evaluation. All patients presented symptoms of dry eye syndrome confirmed with ophthalmic tests. If the diagnosis of GVHD was not an exclusion criterion, Sjögren's syndrome criteria would be met by 4 of our patients - they presented not only with dryness but also with typical antibodies, inflammatory changes in salivary glands on ultrasound examination, and mononuclear cell infiltration in histopathological examination of labial salivary glands. Additionally, three patients presented with scleroderma-like syndromes, but with symptoms easy to differentiate from systemic sclerosis. CONCLUSION: cGVHD may be difficult to distinguish from Sjögren's syndrome, but such distinction is important due to the different standards of treatment in cGVHD and primary connective tissue diseases.

SARS-CoV-2 Infection in Patients Treated with Azacitidine and Venetoclax for Acute Leukemia: A Report of a Case Series Treated in a Single Institution.

INTRODUCTION: Venetoclax combined with azacitidine (AZA-VEN) constitutes an option for the treatment of acute myeloid leukemia. There are, however, no data on the COVID-19 incidence and outcome in patients treated with AZA-VEN. METHODS: Patients with acute leukemia treated with AZA-VEN at a single institution were included in this prospective observational study. RESULTS: Thirteen patients were enrolled, 46% with treatment-naïve, and 56% with relapsed/refractory disease. Fifty-four percent of patients were males; the median age was 69 years. Six patients (46%) developed COVID-19 during the observation time. The median time to COVID-19 was 24 days from the initiation of AZA-VEN. The 2-month cumulative incidence of COVID-19 was 46.2%. Two patients (33%) succumbed to COVID-19. The 100-day COVID-19-free survival from AZA-VEN initiation was 61%. The median follow-up time was 4.3 months. DISCUSSION/CONCLUSION: COVID-19 constitutes a frequent complication of AZA-VEN treatment in the era of the COVID-19 pandemic, leading to death in a significant proportion of patients.

The prevalence of anemia in people with chronic kidney disease after hematopoietic stem cell transplantation.

The hematopoietic stem cell transplantation (HSCT) is performed for various hematological diseases. Chronic kidney disease (CKD) occurs relatively often after HSCT. Anemia after HSCT may be due to CKD and/or other reasons. The aim of this study is to assess the prevalence of anemia and its possible relationship to the presence of CKD in patients at least 3 months after HSCT. The study included 156 patients who underwent allogeneic HSCT treatment in our center in the years 1998 to 2021 due to different hematologic pathologies (acute myeloid leukemia, acute lymphoblastic leukemia, lymphoma, and others). Anemia was diagnosed in 13% of women and 35% of men. Anemia was most common in people after HSCT due to a history of acute myeloid leukemia (55% women, 30% men). In 56% of women and 17% of men, anemia was associated with chronic kidney disease. In patients with anemia, age was related to the eGFR (r = -0.39, p < 0.001), in patients without anemia age was negatively related to eGFR (r = -0.56, p < 0.001), and hemoglobin was positively related to platelet count (r = 0.62, p < 0.001). Concluding, anemia, was relatively common in CKD after HSCT. In CKD, in particular with coexistent anemia, nephrology referral is to be taken into account to optimize therapy, including nephroprotection.

Improved outcome of patients with graft-versus-host disease after allogeneic hematopoietic cell transplantation for hematologic malignancies over time: an EBMT mega-file study.

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<0.001). In multivariate analysis URD, not in complete remission (CR) at transplant or untreated, and female donor for male recipient were factors associated with increased risk whereas the use of ATG/alemtuzumab decreased aGvHD incidence. Median follow-up was 214, 169, 127, 81 and 30 months, respectively, for the periods analyzed. Three-year-survival after aGvHD grades II-IV increased significantly from 38% to 40%, 43%, 44%, and 45%, respectively. In multivariate analysis URD, not in CR at transplant, peripheral blood as stem cell source, female donor for male recipient, and the use of ATG/alemtuzumab were associated with increased mortality whereas reduced-intensity conditioning was linked to lower mortality. Mortality increased with increasing patient age but decreased in the recent cohorts. Our analysis demonstrates that aGvHD has decreased over recent decades and also that the survival rates of patients affected with aGvHD has improved.

Haematological disorders following kidney transplantation.

Transplantation offers cure for some haematological cancers, end-stage organ failure, but at the cost of long-term complications. Renal transplantation is the best-known kidney replacement therapy and it can prolong end-stage renal disease patient lives for decades. However, patients after renal transplantation are at a higher risk of developing different complications connected not only with surgical procedure but also with immunosuppressive treatment, chronic kidney disease progression and rejection processes. Various blood disorders can develop in post-transplant patients ranging from relatively benign anaemia through cytopenias to therapy-related myelodysplasia and acute myeloid leukaemia (AML) and post-transplant lymphoproliferative disorders followed by a rare and fatal condition of thrombotic microangiopathy and haemophagocytic syndrome. So far literature mainly focused on the post-transplant lymphoproliferative disease. In this review, a variety of haematological problems after transplantation ranging from rare disorders such as myelodysplasia and AML to relatively common conditions such as anaemia and iron deficiency are presented with up-to-date diagnosis and management.

The Clinical Tumor Lysis Syndrome in a Patient with Mixed Phenotype Acute Leukemia Undergoing Induction with Venetoclax and Azacitidine: A Case Report.

A combination of azacitidine and venetoclax (AZA-VEN) has been approved for the treatment of adult treatment-naïve acute myeloid leukemia (AML) patients, ineligible for intensive chemotherapy. The protocol may also constitute an alternative for the treatment of patients with mixed phenotype acute leukemia (MPAL), for which no established treatment guidelines exist. It may be anticipated, that alike in AML or chronic lymphocytic leukemia, the treatment of MPAL may be complicated by the tumor lysis syndrome (TLS). No case of TLS in MPAL after VEN has been however reported so far. Here, we present a case of a patient with MPAL, who received AZA-VEN. The patient had a substantial bulk of disease with generalized lymphadenopathy and increased white blood cell count. Despite preventive measures, the patient developed the clinical TLS, which was successfully treated. Based on the current case and other published cases, the incidence of TLS after AZA-VEN was established at 17%.

Inflammasomes-New Contributors to Blood Diseases.

Inflammasomes are intracellular multimeric complexes that cleave the precursors of the IL-1 family of cytokines and various proteins, found predominantly in cells of hematopoietic origin. They consist of pattern-recognition receptors, adaptor domains, and the enzymatic caspase-1 domain. Inflammasomes become activated upon stimulation by various exogenous and endogenous agents, subsequently promoting and enhancing inflammatory responses. To date, their function has been associated with numerous pathologies. Most recently, many studies have focused on inflammasomes' contribution to hematological diseases. Due to aberrant expression levels, NLRP3, NLRP1, and NLRC4 inflammasomes were indicated as predominantly involved. The NLRP3 inflammasome correlated with the pathogenesis of non-Hodgkin lymphomas, multiple myeloma, acute myeloid leukemia, lymphoid leukemias, myelodysplastic neoplasms, graft-versus-host-disease, and sickle cell anemia. The NLRP1 inflammasome was associated with myeloma and chronic myeloid leukemia, whereas NLRC4 was associated with hemophagocytic lymphohistiocytosis. Moreover, specific gene variants of the inflammasomes were linked to disease susceptibility. Despite the incomplete understanding of these correlations and the lack of definite conclusions regarding the therapeutic utility of inflammasome inhibitors, the available results provide a valuable basis for clinical applications and precede upcoming breakthroughs in the field of innovative treatments. This review summarizes the latest knowledge on inflammasomes in hematological diseases, indicates the potential limitations of the current research approaches, and presents future perspectives.

Modern Advances in CARs Therapy and Creating a New Approach to Future Treatment.

Genetically engineered T and NK cells expressing a chimeric antigen receptor (CAR) are promising cytotoxic cells for the treatment of hematological malignancies and solid tumors. Despite the successful therapies using CAR-T cells, they have some disadvantages, such as cytokine release syndrome (CRS), neurotoxicity, or graft-versus-host-disease (GVHD). CAR-NK cells have lack or minimal cytokine release syndrome and neurotoxicity, but also multiple mechanisms of cytotoxic activity. NK cells are suitable for developing an "off the shelf" therapeutic product that causes little or no graft versus host disease (GvHD), but they are more sensitive to apoptosis and have low levels of gene expression compared to CAR-T cells. To avoid these adverse effects, further developments need to be considered to enhance the effectiveness of adoptive cellular immunotherapy. A promising approach to enhance the effectiveness of adoptive cellular immunotherapy is overcoming terminal differentiation or senescence and exhaustion of T cells. In this case, EVs derived from immune cells in combination therapy with drugs may be considered in the treatment of cancer patients, especially effector T and NK cells-derived exosomes with the cytotoxic activity of their original cells.

Increased Intestinal Permeability and Stool Zonulin, Calprotectin and Beta-Defensin-2 Concentrations in Allogenic Hematopoietic Cell Transplantation Recipients.

Significant progress has been made in understanding the connection between intestinal barrier function and allogenic hematopoietic cell transplantation (allo-HCT) recipients' outcomes. The purpose of this study was to further evaluate gut barrier permeability and other potential intestinal barrier disruption markers in the allo-HCT setting. Fifty-one patients were enrolled in the study. Intestinal permeability was assessed with the sugar absorption test and faecal concentrations of the zonulin, calprotectin and beta-defensin-2 levels in the peri-transplantation period. Most patients undergoing allo-HCT in our department had a disrupted intestinal barrier at the baseline, which was associated with older age and higher Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI). Regardless of this, we observed a further increase in gut barrier permeability after allo-HCT in most patients. However, there was no association between permeability assay and other markers (zonulin, calprotectin and beta-defensin-2). Patients with acute GVHD had significantly higher median calprotectin concentrations after allo-HCT compared with the patients without this complication. Our findings indicate that gut barrier damage develops prior to allo-HCT with progression after the procedure and precedes further complications, but did not prove other markers to be useful surrogates of intestinal permeability.

Prevalence of hypogammaglobulinemia and its management with subcutaneous immunoglobulin supplementation in patients after allogeneic hematopoietic stem cell transplantation-a single-center analysis.

Secondary immunodeficiencies are frequently observed after allo-HSCT. The efficacy of subcutaneous IgG preparations in this population is unknown. A retrospective single-institution study involved 126 adult patients transplanted in 2012-2019 for hematological malignancies. Patients were tested every 2-3 weeks for plasma IgG concentration during the 1st year after transplantation and supplemented with facilitated subcutaneous immunoglobulin when they either had IgG concentration < 500 mg/dl or between 500 and 700 mg/dl and recurrent infection. The IgG concentration < 500 mg/dL was diagnosed in 41 patients, while 500-700 mg/dL in 25 and altogether 53 patients received IgG supplementation. The median number of IgG administrations was 2. The median time to the first IgG administration after allo-HSCT was 4.1 months, while to the next administration (if more than one was required) 53 days (prophylactic group) and 32 days (group with infections). We did not observe any significant toxicity. Two situations were associated with increased probability of meeting criteria for IgG supplementation: diagnosis of either acute lymphoblastic leukemia (ALL) or chronic lymphocytic leukemia (CLL) (83.8% versus 39.3% for other diagnosis, p = 0.000) and the systemic use of corticosteroids (64.2% versus 31.5% for patients without systemic corticosteroids, p = 0.005). Over 40% of the adult recipients may require at least incidental immunoglobulin supplementation during the first year after allo-HSCT. Low IgG concentrations are associated with inferior outcomes. The subcutaneous route of IgG administration appeared to be safe and may allow for long persistence.

Azacitidine for relapse of acute myeloid leukemia or myelodysplastic syndrome after allogeneic hematopoietic stem cell transplantation, multicenter PALG analysis.

OBJECTIVES: Relapse of myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) belongs to the major causes of treatment failure. METHODS: Retrospective multicenter analysis of patients diagnosed with AML or MDS who had hematological relapse after allo-HSCT and were treated with azacitidine for this indication. RESULTS: Twenty-three patients receiving azacitidine as the first treatment of relapse (Group_1) and 8 patients receiving azacitidine after other treatment of relapse (Group_2) were included. There were 68% males, median age at initiation of azacitidine was 53 years (15-66). Median time to relapse was 3.5 months and 6.3 months in Group_1 and Group_2, respectively; median time from relapse to azacitidine 0.2 and 2.3 months. Azacitidine 75 mg/m2 , days 1-7, was administered in 78% and 75% of patients in Group_1 and Group_2, concomitant DLI in 48% and 50%. With median follow-up of 4.7 and 13.6 months, the median overall survival was 5.9 and 9.5 months. 17% and 37.5% patients proceeded to salvage allo-HSCT, with median OS of 11.6 months and not reached respectively. CONCLUSIONS: Azacitidine treatment for hematological relapse is associated with poor outcome; nevertheless, a proportion of patients may benefit from it, including patients receiving subsequent salvage allo-HSCT.

Prognostic impact of early-versus-late responses to different induction regimens in patients with myeloma undergoing autologous hematopoietic cell transplantation: Results from the CALM study by the CMWP of the EBMT.

BACKGROUND: In autologous stem cell transplant (ASCT)-eligible myeloma patients, prolonged induction does not necessarily improve the depth of response. METHOD: We analyzed 1222 ASCT patients who were classified based on (a) the interval between induction and stem cell collection, (b) the type of induction regimen: BID (Bortezomib, IMiDs, and Dexamethasone), Bortezomib-based, or CTD (Cyclophosphamide, Thalidomide, and Dexamethasone), and (c) the time to best response (Early ie, best response within 4 or 5 months, depending on the regimen vs Late; Good ie, VGPR or better vs Poor). RESULTS: The length of induction treatment required to achieve a Good response did not affect PFS (P = .65) or OS (P = .61) post-ASCT. The three types of regimen resulted in similar outcomes: median PFS 31, 27.7 and 30.8 months (P = .31), and median OS 81.7, 92.7, and 77.4 months, respectively (P = .83). On multivariate analysis, neither the type nor the duration of the induction regimen affected OS and PFS, except for Early Good Responders who had a better PFS compared to Early Poor Responders (HR = 1.21, P-value = .02). However, achieving a Good response at induction was associated with a better response (≥VGPR) post-transplant. CONCLUSION: The kinetics of response did not affect outcomes.

Eosinophilic gastroenteritis and graft-versus-host disease induced by transmission of Norovirus with fecal microbiota transplant.

Fecal microbiota transplantation (FMT) was performed to decolonize gastrointestinal tract from antibiotic-resistant bacteria before allogeneic hematopoietic cells transplantation (alloHCT). AlloHCT was complicated by norovirus gastroenteritis, acute graft-versus-host disease, and eosinophilic pancolitis. Norovirus was identified in samples from FMT material. Symptoms resolved after steroids course and second norovirus-free FMT from another donor.

Pseudoneutropenia as a factor-limiting access to chemotherapy for cancer patients: the effect of a simple meal.

BACKGROUND: Absolute neutrophil count (ANC) below 1.5 G/l or 1 G/l is commonly used as a factor to determine the decision to administer antineoplastic treatment including chemotherapy and novel agents to cancer patients. This practice is based on observations that below this ANC, there is an increased risk of bacterial and fungal infection. This is further based on the assumption that this parameter always correctly reflects the true shortage of these germ-fighting cells in patients. In reality, the circulating pool of neutrophils is only one of four reservoirs (bone marrow, circulating, marginal and tissue pools) and its size is influenced not only by shortage but also by transient shift of cells between these reservoirs. The aim of this study was to evaluate whether repeated blood collection affects ANC in the patient. METHODS: We retrospectively analysed the medical records of cancer patients with 0.8 G/l ≤ ANC < 1.5 G/l in whom CBC was repeated based on the physician's decision, which was done on the same day roughly 2 h after the first one. RESULTS: The patients at the time of repeating CBC had consumed breakfast. In 31 out of 32 patients, ANC exceeded 1 G/l or 1.5 G/l and antineoplastic treatment was administered as originally planned. There were no infectious complications observed. CONCLUSION: Cancer patients should not be fasting prior to blood collection, with the exception of special and rare situations. To achieve the maximum clinical benefit, delays and/or reductions of antineoplastic treatment should be avoided wherever possible. Pseudoneutropenia is an unnecessary reason for postponing chemotherapy.

Stem cell mobilization in multiple myeloma patients relapsing after previous autologous hematopoietic stem cell transplantation: A multicenter report by the Polish Myeloma Study Group.

BACKGROUND: Salvage autologous hematopoietic stem cell transplantation (autoHSCT) may be used to treat relapse of multiple myeloma occurring after previous autoHSCT. When insufficient number of hematopoietic stem cells was stored from the initial harvest, remobilization of stem cells is necessary. PURPOSE: The analysis of stem cell remobilization after previous autoHSCT. PATIENTS AND METHODS: Fifty-eight patients, 60% males, median 59 years, were included. Median time interval between autoHSCT and remobilization was 42 months. The first remobilization was performed mostly after chemotherapy: cyclophosphamide (33%), cytarabine (43%), and etoposide (19%). RESULTS: The first remobilization was successful in 67% patients. About 19% patients required plerixafor rescue, among whom it allowed for successful harvesting in 14%. Use of cyclophosphamide, cytarabine, and etoposide allowed for successful remobilization in 53%, 84%, and 55% patients, respectively. Patients treated with cytarabine had the highest yield of CD34+ cells (median 7.5 × 106 /kg vs 5.8 and 2.4 for etoposide and cyclophosphamide, P = .001). Higher percentage of patients was able to collect ≥2 × 106 CD34+ cells/kg during one leukapheresis after cytarabine (76% vs 21% for cyclophosphamide vs 36% for etoposide, P = .001). Cytarabine use was associated with lower risk of remobilization failure OR = 0.217, P = .02. Toxicity comprised mostly hematological toxicity (thrombocytopenia and neutropenia). One patient succumbed to septic shock. CONCLUSION: Remobilization after previous autoHSCT is feasible only in a proportion of patients. Cytarabine is associated with the highest rate of successful mobilization and the highest yield of mobilized CD34+ cells. The toxicity requires careful surveillance of these patients.

Impact of pre-transplantation sinus abnormalities assessed by Lund-Mackay scoring system on sinusitis occurrence after allogeneic hematopoietic cell transplantation in acute leukemia patients.

INTRODUCTION: Screening sinonasal evaluation is routinely performed before allogeneic hematopoietic cell transplantation (allo-HCT), however, data supporting such evaluation is inconsistent. O b j e c t i v e s: Assessment of the utility of screening sinonasal evaluation with computed tomography (CT). METHODS: A retrospective analysis of acute leukemia patients who underwent allo-HCT, for whom screening sinonasal CT scans were reevaluated, and for whom Lund-Mackay score (LMS) was calculated. R e s u l t s: Forty-eight patients, the median age at allo-HCT 38 years (18-58), 52% males, were included. 79% had acute myeloid leukemia (AML), 21% acute lymphoblastic leukemia (ALL). Conditioning intensity was myeloablative in 96% of patients, 21% of patients received total body irradiation. 19% of patients had a history of sinusitis before allo-HCT. Screening sinus CT was performed a median of 22 days before allo-HCT. The median LMS was 1 point (0- 10). The severity of sinus abnormalities was: no abnormalities (31%), mild (67%), moderate (2%), severe (0%). Mucosal thickening was the most frequent abnormality (69%). Eleven patients experienced sinusitis after a median of 93 days (11-607) after allo-HCT. 1-year cumulative incidence of sinusitis was 22%. No threshold of LMS and no type of sinus abnormalities were correlated with sinusitis development after allo-HCT. Mild sinus disease at screening did not negatively impact survival in comparison to no sinus disease. C o n c l u s i o n s: Despite the fact, that majority of analyzed patients had either no or mild sinus disease at screening a significant proportion of patients developed sinusitis after allo-HCT. Evaluation of LMS before allo-HCT did not help predict the development of sinusitis after the procedure.

Leukaemia cutis for clinicians, a literature review.

Leukaemia cutis (LC) describes infiltration of the skin by leukaemia cells, resulting in clinically identifiable cutaneous lesions. LC has a wide range of clinical manifestations, which can make it difficult to distinguish LC from other skin changes. In a group of patients, LC can be the first manifestation of leukaemia, therefore skin biopsy is crucial for the diagnosis. In this mini review, we discuss various types of leukaemia most frequently represented in leukaemia cutis, in both children and adults and skin changes in multiple myeloma, focusing on the clinical presentation of LC and prognosis in patients.

Investigation and Management of Bone Mineral Density Following Hematopoietic Cell Transplantation: A Survey of Current Practice by the Transplant Complications Working Party of the European Society for Blood and Marrow Transplantation.

Reduced bone mineral density (BMD) is a well-recognized complication of hematopoietic cell transplantation (HCT), with significant drops in BMD occurring within the first 12 months after HCT. Guidance on identifying and managing this complication is available in several published guidelines. In this study, we investigated current practices in the investigation and management of low BMD in centers registered with the European Society for Blood and Marrow Transplantation (EBMT). A questionnaire about bone health was sent to all registered centers, and responses were received from 99 centers in 25 countries (52%) currently registered with the EBMT. Our data highlight considerable heterogeneity in practices across European centers in relation to investigations, management, and use of guidelines. Our data demonstrate the need for better dissemination and implementation of existing guidelines and also for the development of multidisciplinary guidelines with input from all relevant stakeholders.