Clinical Aspects and Significance of ß-Chemokines, γ-Chemokines, and δ-Chemokines in Molecular Cancer Processes in Acute Myeloid Leukemia (AML) and Myelodysplastic Neoplasms (MDS).

BACKGROUND/OBJECTIVES: Acute myeloid leukemia (AML) is a type of leukemia with a very poor prognosis. Consequently, this neoplasm is extensively researched to discover new therapeutic strategies. One area of investigation is the study of intracellular communication and the impact of the bone marrow microenvironment on AML cells, with chemokines being a key focus. The roles of ß-chemokines, γ-chemokines, and δ-chemokines in AML processes have not yet been sufficiently characterized. METHODS: This publication summarizes all available knowledge about these chemotactic cytokines in AML and myelodysplastic neoplasm (MDS) processes and presents potential therapeutic strategies to combat the disease. The significance of ß-chemokines, γ-chemokines, and δ-chemokines is detailed, including CCL2 (MCP-1), CCL3 (MIP-1α), CCL5 (RANTES), CCL23, CCL28, and CX3CL1 (fractalkine). Additionally, the importance of atypical chemokine receptors in AML is discussed, specifically ACKR1, ACKR2, ACKR4, and CCRL2. RESULTS/CONCLUSIONS: The focus is on the effects of these chemokines on AML cells, particularly their influence on proliferation and resistance to anti-leukemic drugs. Intercellular interactions with non-AML cells, such as mesenchymal stem cells (MSC), macrophages, and regulatory T cells (Treg), are also characterized. The clinical aspects of chemokines are thoroughly explained, including their effect on overall survival and the relationship between their blood levels and AML characteristics.

Stem Cell Mobilization Performed with Different Doses of Cytarabine in Plasma Cell Myeloma Patients Relapsing after Previous Autologous Hematopoietic Cell Transplantation-A Multicenter Report by the Polish Myeloma Study Group.

Salvage autologous hematopoietic cell transplantation (auto-HCT) may be used to treat relapse of plasma cell myeloma occurring after previous auto-HCT. When an insufficient number of hematopoietic stem cells have been stored from the initial harvest, remobilization is necessary. Here, we aimed to analyze the efficacy and safety of different doses of cytarabine (total 800 vs. 1600 vs. 2400 mg/m2) for remobilization. Sixty-five patients, 55% male, with a median age at remobilization 63 years, were included. Remobilization was performed with cytarabine_800 in 7, cytarabine_1600 in 36, and cytarabine_2400 in 22 patients. Plerixafor rescue was used in 25% of patients receiving cytarabine_1600 and 27% of those receiving cytarabine_2400. Patients administered cytarabine_800 were not rescued with plerixafor. Remobilization was successful in 80% of patients (57% cytarabine_800; 86% cytarabine_1600; 77% cytarabine_2400; p = 0.199). The yield of collected CD34+ cells did not differ between the different cytarabine doses (p = 0.495). Patients receiving cytarabine_2400 were at the highest risk of developing severe cytopenias, requiring blood product support, or having blood-stream infections. One patient died of septic shock after cytarabine_2400. In summary, remobilization with cytarabine is feasible in most patients. All doses of cytarabine allow for successful remobilization. Cytarabine_2400 is associated with higher toxicity; therefore, lower doses (800 or 1600 mg/m2) seem to be preferable.

Effect of Hematopoietic Stem Cell Transplantation and Post-Transplantation Cyclophosphamide on the Microglia Phenotype in Rats with Experimental Allergic Encephalomyelitis.

Microglia are the resident immune cells of the central nervous system, playing a role in the inflammatory process development and resolution, presenting two main phenotypes, pro-inflammatory M1, and anti-inflammatory M2. Therapies affecting the microglia phenotype may be beneficial in treating inflammatory neurodegenerative diseases. In our experiments, we used the animal multiple sclerosis model, experimental allergic encephalomyelitis (EAE). Rats were treated during the pre- or symptomatic phase of the disease with cyclophosphamide, followed by hematopoietic stem cell transplantation, and with/without post-transplantation cyclophosphamide. Our study aimed to analyze the microglia phenotype in animals subjected to this treatment. The number of M1 cells in the spinal cord, and inducible nitric oxide synthase (iNOS) levels in the brain were similar in all experimental groups. The differences were observed in M2 cells number and arginase 1 (Arg1) levels, which were decreased in EAE animals, and increased after treatment in the symptomatic phase of EAE, and in the pre-symptomatic phase, but only with post-transplantation cyclophosphamide. Analysis of gene expression in the brain showed decreased iNOS expression in EAE animals treated in the symptomatic phase of EAE and no differences in Arg1 expression. Results indicate that treatment applied to experimental animals influences the microglia phenotype, promoting differentiation towards M2 cells.

Rationale for the Use of Cord Blood in Hypoxic-Ischaemic Encephalopathy.

Hypoxic-ischaemic encephalopathy (HIE) is a severe complication of asphyxia at birth. Therapeutic hypothermia, the standard method for HIE prevention, is effective in only 50% of the cases. As the understanding of the immunological basis of these changes increases, experiments have begun with the use of cord blood (CB) because of its neuroprotective properties. Mechanisms for the neuroprotective effects of CB stem cells include antiapoptotic and anti-inflammatory actions, stimulation of angiogenesis, production of trophic factors, and mitochondrial donation. In several animal models of HIE, CB decreased oxidative stress, cell death markers, CD4+ T cell infiltration, and microglial activation; restored normal brain metabolic activity; promoted neurogenesis; improved myelination; and increased the proportion of mature oligodendrocytes, neuron numbers in the motor cortex and somatosensory cortex, and brain weight. These observations translate into motor strength, limb function, gait, and cognitive function and behaviour. In humans, the efficacy and safety of CB administration were reported in a few early clinical studies which confirmed the feasibility and safety of this intervention for up to 10 years. The results of these studies showed an improvement in the developmental outcomes over hypothermia. Two phase-2 clinical studies are ongoing under the United States regulations, namely one controlled study and one blinded study.

Ice-cream used as cryotherapy during high-dose melphalan conditioning reduces oral mucositis after autologous hematopoietic stem cell transplantation.

Oral mucositis (OM) is one of the most frequent adverse events of high-dose conditioning chemotherapy with melphalan prior to autologous hematopoietic stem cell transplantation (AHSCT). It significantly reduces the patients' quality of life. One of the preventive strategies for OM is cryotherapy. We retrospectively analyzed whether commercially available ice-cream could prevent OM during the melphalan infusion. We retrospectively analyzed 74 patients after AHSCT to see whether there is any correlation between OM and cryotherapy (ice-cream), melphalan dose (140 mg/m2 or 200 mg/m2). The incidence of OM in our study inversely correlated with cryotherapy in the form of ice-cream. Out of 74 patients receiving conditioning chemotherapy with high-dose melphalan, 52 received cryotherapy. Fifteen patients in the cryotherapy group (28.84%) developed OM, whereas 13 patients (59.09%) developed it in the group without cryotherapy. In a multiple linear regression test cryotherapy remained a significant protective factor against OM (p = 0.02) We have also seen the relationship between melphalan dose with OM (p < 0.005). Cryotherapy in the form of ice-cream is associated with a lower rate of OM and, therefore, could potentially be used as a cost-effective, less burdensome, and easy to implement method in prevention of oral mucositis.

Risk of infectious complications in adult patients after allogeneic hematopoietic stem cell transplantation depending on the site of central venous catheter insertion-multicenter prospective observational study, from the IDWP EBMT and Nurses Group of EBMT.

The current guidelines for prevention of infections in hematopoietic stem cell transplantation (HSCT) do not specify which central venous catheter (CVC) insertion site should be preferred in allogeneic HSCT recipients-internal jugular vein (IJV) or subclavian vein (SCV). We designed a multicenter prospective observational study comparing the risk of infectious and non-infectious complications between the two most common sites of CVC insertion (IJV and SCV) in allogeneic HSCT. There were in total 232 consecutive patients (86 IJV and 146 SCV) who underwent adult allogeneic HSCT reported from 11 centers in 8 countries. The center independent analysis of central line associated/related blood stream infections with ECDC criteria has shown statistically significant difference favoring SCV (23% IJV vs 13% SCV (OR 2.03 (1.01-4.06), p = 0.047)). The differences in CLABSI per 1000 days of CVC use favored SCV over IJV (7.93/1000 days IJV vs 2.79/1000 days SCV, p = 0.002). The frequency of all non-infectious complications was similar in both arms-13% IJV and 12% SCV (OR 1.1 (0.5-2.5), p = 0.8). This multicenter prospective study showed statistically significant lower confirmed number of CLABSI per 1000 days of CVC use without higher risk of noninfectious complications related to the subclavian insertion site in allogeneic HSCT recipients.

Post Transplantation Cyclophosphamide Improves Outcome of Autologous Hematopoietic Stem Cell Transplantation in Animal Model of Multiple Sclerosis.

Experimental allergic encephalomyelitis (EAE) is the animal model of multiple sclerosis (MS). Autologous hematopoietic stem cell transplantation (AHSCT) has recently been recognized as the standard treatment for MS. The aim of our experiment was to investigate the effect of AHSCT with the addition of low-dose post-transplantation cyclophosphamide (Cy) on EAE in rats. Low dose post-transplantation Cy is used in haploidentical HSCT to reduce the risk of graft versus host disease. We hypothesized that it could bring additional benefit in autologous HSCT in autoimmune diseases. Rats with evoked EAE were treated with high dose (125 mg/kg) Cy, followed by AHSCT or high dose (125 mg/kg) Cy followed by AHSCT followed by low dose (20 mg/kg) Cy in two-time schedules-with the therapy applied during the pre-symptomatic or symptomatic phase of the disease. Both AHSCT and AHSCT with post-transplantation Cy in accordance with both time schedules reduce the intensity of the inflammatory response in the CNS, in comparison with non-treated EAE rats. The reduction of clinical symptoms was present in all AHSCT treatment protocols, however, it was significantly stronger when post-transplantation Cy was given during the symptomatic phase of the disease. AHSCT with the addition of post HSCT low dose Cy improved the results of AHSCT by not only reducing the intensity of inflammation in the CNS but also by significantly reducing the clinical symptoms in treated animals when compared to AHSCT alone. We provide an experimental rationale that the addition of post-transplantation Cy may improve the outcome of HSCT in MS.

Hematopoietic stem cell transplantation for autoimmune diseases in the time of COVID-19: EBMT guidelines and recommendations.

Coronavirus disease-19 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), represents one of the biggest challenges of 21st century, threatening public health around the globe. Increasing age and presence of co-morbidities are reported risk factors for severe disease and mortality, along with autoimmune diseases (ADs) and immunosuppressive treatments such as haematopoietic stem cell transplantation (HSCT), which are also associated with adverse outcomes. We review the impact of the pandemic on specific groups of patients with neurological, rheumatological, and gastroenterological indications, along with the challenges delivering HSCT in adult and pediatric populations. Moving forward, we developed consensus-based guidelines and recommendations for best practice and quality of patient care in order to support clinicians, scientists, and their multidisciplinary teams, as well as patients and their carers. These guidelines aim to support national and international organizations related to autoimmune diseases and local clinical teams delivering HSCT. Areas of unmet need and future research questions are also highlighted. The waves of the COVID-19 pandemic are predicted to be followed by an "endemic" phase and therefore an ongoing risk within a "new normality". These recommendations reflect currently available evidence, coupled with expert opinion, and will be revised according to necessary modifications in practice.

Impact of Immunoablation and Autologous Hematopoietic Stem Cell Transplantation on Treatment Cost of Multiple Sclerosis: Real-World Nationwide Study.

OBJECTIVES: To provide real-world data on the impact of autologous hematopoietic stem cell transplantation (AHSCT) on treatment costs of patients with multiple sclerosis (MS) in Poland. METHODS: Medical data of 105 patients who underwent AHSCT in the years 2011 to 2016 were obtained from the National Health Fund (NHF) database. Treatment costs were calculated from the public payer's perspective per patient-year for the total available period as well as 12 months before and after AHSCT. The statistical analysis was performed using MATLAB 2016b. RESULTS: Mean treatment-related costs covered by the NHF per patient-year before and after the transplantation were €4314.9 and €1188.8 , respectively. The average cost of disease-modifying drugs per patient was reduced from €2497.9/year before to €65.3/year after AHSCT. CONCLUSIONS: Although the initial cost of AHSCT is high, the costs involving AHSCT and post-AHSCT treatment could, according to our analysis, pay off in 3.9 years, when compared to the costs of disease-modifying drug therapy in aggressive MS. The study provides evidence that the AHSCT can lead to significant savings in treatment costs of aggressive MS from the public payer's perspective.

Seasonal variation of human physiology does not influence the harvest of peripheral blood CD34+ cells from unrelated hematopoietic stem cell donors.

There are many reports on factors predicting the outcome of PBSC (peripheral blood stem cell) mobilization, such as the donor's gender, age, weight, white blood cell count, platelets pre apheresis, LDH and iron status. Although there are reports of seasonal variation in the physiology of the human immune system and hematopoiesis there are no data that such differences play a role in the response to G-CSF in healthy hematopoietic stem cell donors. The response to G-CSF could also impact the collection results during different seasons. To assess the possible impact of seasonal variation we performed a retrospective, single-center analysis of mobilization and harvest of PBSC in 330 healthy unrelated donors. We found no significant differences in the number of CD34+ cells in peripheral blood after G-CSF mobilization and in collection results when all donors were analyzed. In the subgroup of male donors the number of CD34+ stem cells after G-CSF mobilization was higher than average in summer and autumn (p = 0.036), however, it did not translate into clinically relevant differences in stem cell harvest. We conclude that although there is possible seasonal variation in the response to G-CSF in male donors there is no impact on PBSC harvest in healthy unrelated donors.

EQ-5D-Derived Health State Utility Values in Hematologic Malignancies: A Catalog of 796 Utilities Based on a Systematic Review.

OBJECTIVES: We performed a systematic review of health state utility values (HSUVs) obtained using the EQ-5D questionnaire for patients with hematologic malignancies. METHODS: The following databases were searched up to September 2018: MEDLINE, EMBASE, The Cochrane Library, and the EQ-5D publications database on the EuroQol website. Additional references were extracted from reviewed articles. Only studies presenting EQ-Index results were incorporated. In view of the heterogeneity across the included publications, we limited ourselves to a narrative synthesis of original HSUVs found. RESULTS: Fifty-nine studies (described in 63 articles) met the inclusion criteria. Data from 21 635 respondents provided 796 HSUV estimates for hematologic malignancy patients. EQ-Index scores ranged from -0.025 to 0.980. The most represented area was multiple myeloma (4 studies, 11 112 patients, and 249 HSUVs). In clinical areas such as chronic myeloid leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, non-Hodgkin lymphoma, and mantle cell lymphoma, we described over 50 health utilities in each. In contrast, we identified only 13 HSUVs (based on 4 studies and the data of 166 patients) for Hodgkin lymphoma. Areas without EQ-5D-based health utilities comprised: polycythemia vera, primary myelofibrosis, essential thrombocythemia, mastocytosis, myeloid sarcoma, chronic myelomonocytic, eosinophilic leukemia, and neutrophilic leukemia. CONCLUSIONS: There is a wide range of HSUVs available for hematologic cancer patients with different indications. The review provides a catalog of utility values for use in cost-effectiveness models for hematologic malignancies.

Negative Impact of Borderline Creatinine Concentration and Glomerular Filtration Rate at Baseline on the Outcome of Patients With Multiple Myeloma Treated With Autologous Stem Cell Transplant.

BACKGROUND: Renal impairment (RI) is one of the multiple myeloma (MM)-defining events for initiating therapy. After induction therapy, high-dose chemotherapy followed by autologous peripheral blood stem cell transplant (ASCT) remains the standard of care for transplant-eligible patients with MM. According to the International Myeloma Working Group (IMWG), the organ criterion for kidney damage is defined by a serum creatinine concentration (CrC) > 2 mg/dL or estimated glomerular filtration rate (eGFR) < 40 mL/min. In this long-term study, we evaluated the impact of CrC and eGFR calculated by the Modification of Diet in Renal Disease equation on progression-free and overall survival using a lower threshold than the IMWG criteria. PATIENTS AND METHODS: We studied the longitudinal outcomes as measured by progression-free survival and overall survival in 59 transplant-eligible patients with MM: 38 patients with normal renal function and 21 patients with RI defined as a CrC higher than upper limit of normal (≥ 1.1 mg/dL), eGFR < 60 mL/min, treated with ASCT from 1998 to 2004. RESULTS: The risk of disease progression and death following ASCT increased by 16.5% (P = .005) and 19% (P < .0009) per 1 mg/dL of CrC, respectively. The thresholds for the association of renal insufficiency and negative outcomes were CrC > 1.4 mg/dL and eGFR < 55mL/min. CONCLUSIONS: We observed a negative correlation between minimal renal insufficiency and long-term outcomes. Management of patients with even marginally increased CrC and/or decreased eGFR not fulfilling IMWG RI criteria requires more concentrated effort to reverse even minimal renal insufficiency.

Prior blood donations do not affect efficacy of G-CSF mobilization nor outcomes of haematopoietic stem cell collection in healthy donors.

BACKGROUND AND OBJECTIVES: Many consider volunteer blood donors as ideal candidates for unrelated haematopoietic progenitor cell (HPC) donation. However, frequent blood donations could influence the results of HPC mobilization. To our best knowledge, there are no data on the possible impact of repeated blood donation on efficiency of subsequent HPC mobilization by granulocyte colony-stimulating factor (G-CSF). MATERIALS AND METHODS: We compared outcomes of HPC mobilization in unrelated donors with and without a history of blood donation. We conducted a prospective study on 287 consecutive donors admitted to the Department of Hematology since January 2016. The final analysis included 153 donors who agreed to take part in the study and had undergone stem cell mobilization with G-CSF. RESULTS: History of blood donations prior to haematopoietic stem cell mobilization with G-CSF does not have a significant impact on the number of collected CD34+ cells in the first leucocytapheresis (516.2 x 106 (170-1148) in blood donors vs 490.5 x 106 (101-1154) in non-donors) (P = 0.32). In all donors, in this study mobilization of HPC was successful: 87.5% of blood donors and 85.6% of non-donors collected the required cell number in a single apheresis. In blood donors, a higher number of blood donations within 2 and 5 years prior to HPC mobilization correlated significantly with successful donation within one leucocytapheresis (P = 0.014 and P = 0.024, respectively). CONCLUSION: Multiple blood donations do not significantly influence the outcome of HPC collection in unrelated donors. Blood donors and non-donors have similar results of HPC collection, so there is no reason to favour either group.

Bone marrow harvest in donors with anaemia.

BACKGROUND: Bone marrow harvest (BMH) for haematopoietic stem cell transplantation is a well-established procedure. The guidelines of World Marrow Donor Association provide information on donor selection. However, some of the guidelines regarding donors with anaemia prior to harvest lack in supporting data from clinical studies. With this study, we aimed to provide such data. MATERIAL AND METHODS: In this retrospective, single-centre study, we analysed the interplay between haemoglobin levels and BMH and BMH impact on haemoglobin levels in a cohort of 149 unrelated BM donors, including 13 subjects with mild anaemia. RESULTS: The BMH led to significantly lower decrease in haemoglobin levels in donors with anaemia than in control group (1·79 g/dl vs. 2·56 g/dl, P < 0·0001). The following parameters: BMH volume (ml), BMH volume/donor body weight (ml/kg), total nucleated cells (TNC) in product (×108 ) and TNC/kg recipient body weight in product (×108 /kg) did not differ significantly between those two analysed groups (P > 0·05). Median BM volume harvested from anaemic donors was 16·34 ml/kg; none of them required blood transfusion after BMH. CONCLUSION: Mild anaemia prior to BMH does not significantly impact the collection results. The BMH is safe and feasible in donors with mild anaemia.

Lack of persistent remission following initial recovery in patients with type 1 diabetes treated with autologous peripheral blood stem cell transplantation.

AIMS: To assess metabolic control in patients with newly diagnosed type 1 diabetes mellitus who underwent immunoablation followed by autologous peripheral blood stem cell transplantation (APBSCT) as a treatment of diabetes. METHODS: APBSCT was performed in 23 patients. Control group comprised 8 non-APBSCT patients in whom after diagnosis insulin therapy was initiated. Fasting plasma glucose, glycated hemoglobin, fasting and postprandial C-peptide were assessed in all subjects and continuous glucose monitoring was performed at 6th, 12th, 24th, 36th, 48th month after transplantation. The APBSCT group was observed for 72 months. RESULTS: Six months after the procedure, 22 of 23 transplant patients remained insulin-free, but after 6 years, there was only one APBSCT insulin-free patient. Good glycemic control was observed in all patients throughout the observation period, although fasting plasma glucose in control group was significantly higher in comparison with the both transplanted groups up to the 36th month. HbA1c values were significantly lower in the insulin-free group only at the 24th and 36th month. Fasting and postprandial C-peptide concentrations were higher in APBSCT group as compared with control group. The most serious adverse event was a fatal case of Pseudomonas aeruginosa sepsis. CONCLUSIONS: The effectiveness of APBSCT as a treatment for newly diagnosed DM1 seems to be limited in time. The metabolic control of APBSCT patients is similar to conventionally treated patients. The lower fasting plasma glucose and higher C-peptide achieved with APBSCT seem to not exceed the risks associated with the procedure.

Autologous peripheral blood stem cell transplantation in dialysis-dependent multiple myeloma patients-DAUTOS Study of the Polish Myeloma Study Group.

INTRODUCTION: Dialysis-dependent (DD) multiple myeloma patients (MM) have a poor prognosis and high tumour burden, thus may benefit from autologous peripheral blood stem cell transplantation (auto-PBSCT), however, these patients have an increased risk of toxicity. AIMS: To evaluate the outcomes (toxicity, PFS, OS) of high dose therapy followed by auto-PBSCT during an observational study and after propensity score matching. PATIENTS AND METHODS: Between 2004-2015, 24 DD patients, (aged 38-67 years), ISS 3, treated with auto-PBSCT, requiring dialysis at diagnosis and auto-PBSCT were evaluated, matched and compared to 55 normal renal function MM patients (NRF) with ISS 3 for outcomes of interest. RESULTS: In DD patients compared to NRF patients risk of mucositis (88% vs 55%), infection (79% vs 51%), parenteral nutrition (50% vs 24%), diarrhoea (71% vs 38%), prolonged duration of hospitalisation (medians: 30 vs 21 days), requirement for RBC transfusion (83% vs 36%) were significantly higher, while no significant differences were found in post-transplant response (ORR; 75% vs 87%), 5-year PFS (36% vs 20%) and OS (39% vs 50%). Subgroup analyses based on toxicity supported these results. CONCLUSIONS: Despite the increased risk of toxicity in DD patients these events do not significantly affect both the PFS and OS.

Continuous Mononuclear Cell Collection (cMNC) protocol impact on hematopoietic stem cell collections in donors with negative collection predictors.

BACKGROUND: Recently, novel protocol utilizing Continuous Mononuclear Cell Collection (cMNC) have been introduced for leukapheresis. We compared the efficacy of cMNC with an older protocol - mononuclear cell collection (MNC) for CD34+ cell collection in unrelated donors with negative stem cell collection predictors. MATERIAL AND METHODS: Retrospective data from a series of 258 consecutive unrelated hematopoietic stem cell donors was included in this single-center study (80 donors collected with cMNC and 178 with MNC). The donors with poor predictors for collection such as low number of circulating CD34+ cells and/or weight disproportion were assigned to the cMNC arm. RESULTS: The cMNC protocol yielded a higher number of CD34 + cells per donor body weight (7.63 × 106/kg vs 6.82 × 106/kg, p = 0.027). One apheresis was sufficient for collection of target cell number in 89% individuals from both groups despite negative predictors in the cMNC group. In donors with CD34 + cell count <100/µL and a body weight disproportion between donor and recipient one apheresis was sufficient in 83% of donors in cMNC group and in 58% in MNC group (p = 0.0345) with collection efficiency CE2% values of 61% for cMNC and 62% for MNC (p = 0.77). CONCLUSION: cMNC protocol is more efficient in donors with low pre-apheresis CD34+ cell count and weight disproportion between donor and recipient. This suggests that the use of cMNC in unrelated donors could possibly further improve the results of HSC collections.

Experience with Saccharomyces boulardii Probiotic in Oncohaematological Patients.

Very few reports have been published to date on the bloodstream infections caused by Saccharomyces spp. in oncohaematological patients, and there are no guidelines on the use of this probiotic microorganism in this population. We describe the use of probiotic preparation containing Saccharomyces boulardii in a large group of oncohaematological patients. We retrospectively analysed the data from 32,000 patient hospitalisations at the haematological centre during 2011-2013 (including 196 haematopoietic stem cell transplant recipients) in a tertiary care university-affiliated hospital. During the study period, 2270 doses of Saccharomyces boulardii probiotic were administered to the oncohaematological patients. In total, 2816 mycological cultures were performed, out of which 772 (27.4%) were positive, with 52 indicating digestive tract colonisation by Saccharomyces spp., mainly in patients with acute myeloid leukaemia (AML), myelodysplastic syndrome (MDS) or multiple myeloma (MM). While colonised, they were hospitalised for 1683 days and 416 microbiological cultures of their clinical samples were performed. In the studied group of patients, there were six blood cultures positive for fungi; however, they comprised Candida species: two C. glabrata, one C. albicans, one C. krusei, one C. tropicalis and one C. parapsilosis. There was no blood culture positive for Saccharomyces spp. Our study indicates that despite colonisation of many oncohaematological patients with Saccharomyces spp., there were no cases of fungal sepsis caused by this species.