Association of bone mineral density and potential risk factors for osteoporosis in patients with severe haemophilia A.

INTRODUCTION: In people with haemophilia (PWH), recurrent episodes of bleeding lead to joint deterioration and bone resorption. To date, the effects of various other factors on bone mineral density (BMD) reduction have found conflicting results. AIM: The aim of this study was to analyse the relationships between BMD, bone mineral content (BMC), and trabecular bone score (TBS) parameters based on the dual X-ray absorptiometry method (DXA) and potential risk factors for osteoporosis in patients with severe haemophilia A. METHODS: Fifty-five men with severe haemophilia A, aged 18-68 years, and 59 healthy volunteer men were enrolled in this study. Densitometric-derived lumbar spine and femoral neck BMD, BMC, and TBS were measured. Blood analyses were performed for morphology parameters, liver and kidney function parameters, and viral status. Serum levels of oestradiol (E2 ), testosterone (T), dehydroepiandrosterone sulphate (DHEA-S), parathormone, and vitamin D were measured. RESULTS: Patients showed significantly lower BMD compared to controls (p < .003). The result below the expected range for age was nearly double (6.82% vs. 3.92%) in PWH under 50 years old compared to controls. Haemophilic patients also exhibited significantly higher vitamin D3 deficiency (p < .0001), which was strongly associated with low TBS. Additionally, low body mass index and high neutrophil/lymphocyte ratio were correlated with low BMC and BMD. CONCLUSIONS: This study confirms the prevalence of low BMD and BMC in patients with haemophilia in Poland. Factors that contribute to low BMD are primarily vitamin D deficiency, low BMI, high neutrophil/lymphocyte ratio, and low testosterone/oestradiol ratio.

CD117 (c-kit) expression on CD34+ cells participates in the cytogenetic response to imatinib in patients with chronic myeloid leukemia in the first chronic phase.

BACKGROUND: Chronic myeloid leukemia (CML) biology seemed to be perfectly explored especially at the beginning of the tyrosine kinase inhibitors era. Later years with imatinib and second-generation tyrosine kinase inhibitors showed a variety of resistance mechanisms and it became obvious that the bcr-abl chimeric gene is not the only enemy to fight. Some studies assumed the decreased rate of programmed cell death (apoptotic) to be the primary mechanism by which BCR-ABL affects expansion of the leukemic clone in CML. Therefore, the aim of this study was to investigate the role of c-kit inhibition in treatment response. METHODS: Cytogenetic analysis, real-time quantitative reverse-transcriptase polymerase chain reaction, flow-cytometric analysis and imatinib serum level quantification were applied. RESULTS: The percentage of CD34+ cells expressing c-kit (CD117) isolated from bone marrow samples of 54 CML patients treated with standard-dose imatinib was significantly lower among imatinib responders. The fraction of apoptotic CD34+CD117+ cells in this patient group was significantly higher than in nonresponders. CONCLUSION: To achieve optimal treatment response in CML patients, the elimination of CD34+CD117+ may be necessary through an apoptotic pathway.

Expression of PIM-2 and NF-κB genes is increased in patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) and is associated with complete remission rate and overall survival.

INTRODUCTION: PIM-2 is a proto-oncogene that encodes for a serine/threonine kinase that interacts with various signaling molecules. PIM-2 is highly expressed in neoplastic tissues and in leukemic and lymphoma cell lines, which is consistent with its role during oncogenic transformation. The nuclear factor kappa B (NF-κB) pathway appears to be deregulated in a variety of tumors, with sustained activity of NF-κB leading to apoptotic resistance in tumor cells. The aim of this study was to investigate whether expression of PIM-2 and NF-κB is altered in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: One hundred forty-three patients were included: 91 with AML and 52 with ALL, aged 18-84 (median 46.7). Eighty-three patients (51 AML and 32 ALL) reached complete remission (CR). Bone marrow samples were collected at the time of diagnosis. Control samples were obtained from 24 healthy donors. We analyzed PIM-2 and NF-κB expression by RQ-PCR analysis. RESULTS: Expression of both PIM-2 and NF-κB in all leukemia patients and subgroups was significantly higher than in controls. AML patients who reached CR expressed PIM-2 and NF-κB at significantly lower levels than did patients with primary resistance to chemotherapy and who did not reach CR (NCR). Survival analysis revealed that in AML patients with higher expression of PIM-2 the overall survival (OS) was significantly shorter than in patients with lower expression. CONCLUSION: Our data indicate that PIM-2 and NF-κB gene expression is increased in patients with AML and ALL. Moreover, high PIM-2 expression is associated with CR rate and OS in AML patients.

CD8+CD28-lymphocytes in peripheral blood and serum concentrations of soluble interleukin 6 receptor are increased in patients with Graves' orbitopathy and correlate with disease activity.

BACKGROUND: The extrathyroid, orbital manifestation of Graves' disease (GD)--Graves' orbitopathy (GO)--presents a difficult clinical problem. The immunological status of GO patients is still under investigation. The aim of this study was to assess the serum concentration of interleukin 6 (IL-6), soluble interleukin 6 receptor (sIL-6R), and CD8+CD28- lymphocytes in GO patients and to evaluate if these parameters were associated with disease activity. PATIENTS: Thirty-nine patients (29 women and 10 men, aged 24-71, mean 50.18) with newly diagnosed GD were enrolled in the study. Active GO was diagnosed in 20 patients. The control group included 12 healthy individuals. METHODS: Serum concentrations of IL-6 and sIL-6R were estimated by ELISA. Percentages of CD8+CD28- lymphocytes in peripheral blood were assessed by flow cytometry. RESULTS: Mean serum IL-6 and sIL-6R concentrations were significantly higher in all GD patients and in GO and non-GO patients than in normal controls. In all GD patients and the non-GO group, serum IL-6 and sIL-6R concentrations were significantly reduced after efficient treatment. In GO patients, only serum sIL-6R concentration was significantly lower after efficient treatment. In all GD patients, the mean percentage of CD8+CD28- lymphocytes was significantly lower after efficient treatment. In GO patients, the mean percentage of CD8+CD28- lymphocytes was significantly higher than in the non-GO group or in normals. Moreover, in the GO group, the mean percentage of CD8+CD28- lymphocytes was significantly lower after treatment. CONCLUSION: Our results have shown that CD8+CD28- lymphocyte percentage in peripheral blood and serum concentration of sIL-6R are increased in GO patients and correlate with disease activity.

BKV Related Hemorrhagic Cystitis-An Insight into Risk Factors and Later Complications-An Analysis on Behalf of Polish Adult Leukemia Group.

BK virus reactivation increases the likelihood of hemorrhagic cystitis (HC) after allogeneic hematopoietic stem cell transplant (HCT). In this study, we aimed to identify predictive and risk factors associated with the increased occurrence of this condition following HCT. On a group of 124 patients aged ≤71 years old (median 40 years) who underwent HCT, we analyzed sex, age, time from diagnosis to transplantation, type of conditioning, donor's relationship, age, and sex, the impact of immunosuppression with different drugs, and acute and chronic GVHD, BK viremia and viruria as potential factors increasing the risk of BK-related HC after HCT. HC occurred among 24 patients (24/124; 29.2%). A significant correlation was observed between HC incidences after HCT, BK viremia and viruria, and acute GVHD occurrence. Furthermore, the level of BKV DNA in serum at day +21 (>0.75 × 103) significantly impacted the patients' survival time. According to our results, the likelihood ratio of BKV-DNA on day +21 in serum is 6.25, indicating that this diagnostic test has the potential to be utilized in a clinical setting. These findings may be used as a voice in the discussion on implementing an optimal preemptive treatment in BKV reactivation after allogeneic HCT.

Hematopoietic stem cell mobilization with the reversible CXCR4 receptor inhibitor plerixafor (AMD3100)-Polish compassionate use experience.

Recent developments in the field of targeted therapy have led to the discovery of a new drug, plerixafor, that is a specific inhibitor of the CXCR4 receptor. Plerixafor acts in concert with granulocyte colony-stimulating factor (G-CSF) to increase the number of stem cells circulating in the peripheral blood (PB). Therefore, it has been applied in the field of hematopoietic stem cell mobilization. We analyzed retrospectively data regarding stem cell mobilization with plerixafor in a cohort of 61 patients suffering from multiple myeloma (N = 23), non-Hodgkin's lymphoma (N = 20), or Hodgkin's lymphoma (N = 18). At least one previous mobilization attempt had failed in 83.6% of these patients, whereas 16.4% were predicted to be poor mobilizers. The median number of CD34+ cells in the PB after the first administration of plerixafor was 22/µL (range of 0-121). In total, 85.2% of the patients proceeded to cell collection, and a median of two (range of 0-4) aphereses were performed. A minimum of 2.0 × 10(6) CD34+ cells per kilogram of the patient's body weight (cells/kg b.w.) was collected from 65.6% of patients, and the median number of cells collected was 2.67 × 10(6) CD34+ cells/kg b.w. (0-8.0). Of the patients, 55.7% had already undergone autologous stem cell transplantation, and the median time to neutrophil and platelet reconstitution was 12 and 14 days, respectively. Cases of late graft failure were not observed. We identified the diagnosis of non-Hodgkin's lymphoma and previous radiotherapy as independent factors that contributed to failure of mobilization. The current report demonstrates the satisfactory efficacy of plerixafor plus G-CSF for stem cell mobilization in heavily pre-treated poor or predicted poor mobilizers.

Early Administration of Convalescent Plasma Improves Survival in Patients with Hematological Malignancies and COVID-19.

The use of convalescent plasma in the treatment of COVID-19 may lead to a milder course of infection and has been associated with improved outcomes. Determining optimal treatments in high risk populations is crucial, as is the case in those with hematological malignancies. We analyzed a cohort of 23 patients with hematological malignancies and COVID-19 who had received plasma 48-72 h after the diagnosis of infection and compared it with a historical group of 22 patients who received other therapy. Overall survival in those who received convalescent plasma was significantly higher than in the historical group (p = 0.03460). The plasma-treated group also showed a significantly milder course of infection (p = 0.03807), characterized by less severe symptoms and faster recovery (p = 0.00001). In conclusion, we have demonstrated that convalescent plasma is an effective treatment and its early administration leads to clinical improvement, increased viral clearance and longer overall survival in patients with hematological malignancies and COVID-19. To our knowledge, this is the first report to analyze the efficacy of convalescent plasma in a cohort of patients with hematological malignancies.

Fecal microbiota transplantation in the treatment of intestinal steroid-resistant graft-versus-host disease: two case reports and a review of the literature.

Acute graft-versus-host disease (aGvHD) reduces the efficiency and safety of allogeneic hematopoietic stem cell transplantation (allo-HSCT). In recent years, attempts have been made to transplant fecal microbiota from healthy donors to treat intestinal GvHD. This study presented two cases of patients undergoing allo-HSCT who were later selected for fecal microbiota transplantation (FMT). In the first patient, FMT resulted in the complete resolution of symptoms, whereas therapeutic efficacy was not achieved in the second patient. FMT eliminated drug-resistant pathogens, namely very drug-resistant Enterococcus spp., but not multidrug-resistant Acinetobacter baumannii or Candida spp. Further research is needed, particularly on the safety of FMT in patients with intestinal steroid-resistant GvHD and on the distant impact of transplanted microflora on the outcomes of allo-HSCT. FMT appears promising for the treatment of patients with steroid-resistant GvHD.

High intracellular content of cyclin-dependent kinase inhibitor p27(Kip1) in early- and intermediate stage B-cell chronic lymphocytic leukemia lymphocytes predicts rapid progression of the disease.

Previous studies showed that peripheral blood lymphocytes of B-cell chronic lymphocytic leukemia (B-CLL) displayed a high intracellular level of cell cycle inhibitory protein p27(Kip1). It has been suggested that its' high expression may confer them survival advantage and lead to unfavorable prognosis, but the prognostic significance of p27(Kip1) expression for previously untreated, non-advanced stage B-CLL was not established. We studied a relationship between the intracellular level of p27(Kip1) of lymphocytes of early- and intermediate stage B-CLL patients and their spontaneous apoptosis in vitro, as well as prognostic significance of p27(Kip1) in B-CLL lymphocytes for the risk of disease progression. Intracellular p27(Kip1) content of peripheral blood lymphocytes obtained from 48 previously untreated 0-II Rai stage B-CLL patients was determined by flow cytometry. The viability and apoptosis of those lymphocytes after 72-h culture were also assessed. During the follow-up period (6-71 months, median 59.5), we recorded the time elapsed to the doubling of lymphocyte count, progression to a higher Rai stage and the appearance of indications for cytostatic treatment. The p27(Kip1) expression was neither correlated with initial lymphocyte count, CD38 expression, cell viability nor spontaneous apoptosis ratio after 72-h culture. Higher p27(Kip1) level was related to the probability of earlier occurrence of each of three above-mentioned events. We did not find a prognostic significance of in vitro cell viability nor apoptosis as to the risk of disease progression. Our results indicate that elevated intracellular p27(Kip1) level in leukemic lymphocytes of early- and intermediate stage B-CLL patients contributes to rapid progression of the disease.

Increased percentage of CD8+CD28- suppressor lymphocytes in peripheral blood and skin infiltrates correlates with advanced disease in patients with cutaneous T-cell lymphomas.

INTRODUCTION: T cells with the CD8+CD28- phenotype are CD8+ lymphocytes with regulatory function. Their increased numbers were observed in infections, autoimmune and neoplastic diseases, and in elderly healthy individuals. CD8+CD28- lymphocyte levels in patients with cutaneous T-cell lymphoma (CTCL) has not yet been described. The aim of the study was to determine their levels in these patients' peripheral blood and cutaneous infiltrates and their relation to the clinical stage of disease. MATERIAL/METHODS: Forty-one untreated patients, 26 males and 15 females, with CTCL were enrolled in the study. CD8+CD28- lymphocyte levels were determined by flow cytometry in peripheral blood and by immunochemistry in skin infiltrates. RESULTS: The percentage of CD8+CD28- lymphocytes in the peripheral blood of the patients was significantly higher than in the controls. Patients with advanced disease displayed a higher percentage of CD8+CD28- lymphocytes in the peripheral blood and skin than did the individuals with early stages of the disease. Moreover, positive correlations between CD8+CD28- lymphocyte level in peripheral blood and age, clinical stage, and the levels in the skin infiltrates was revealed. Additionally, the percentage of CD8+CD28- T cells in the skin infiltrates correlated positively with age and clinical stage of the disease. CONCLUSIONS: These data suggest that CD8+CD28- lymphocytes play an important role in the development of immunotolerance in the progression of cutaneous T-cell lymphoma.

Expression of the PIM2 gene is associated with more aggressive clinical course in patients with chronic lymphocytic leukemia.

BACKGROUND: The PIM2 gene belongs to the PIM family, which encodes serine/threonine kinases involved in cell survival and apoptosis. The relation between the expression of the PIM2 gene and the course of chronic lymphocytic leukemia (CLL) has not been fully determined. OBJECTIVES: The aim of the study was to evaluate the role of the PIM2 gene as a marker of CLL malignancy and its importance as a predictive and prognostic factor. MATERIAL AND METHODS: Sixty-seven patients, 35 females and 32 males, aged 49-90 years, with de novo CLL, and 14 healthy individuals were enrolled in the study. Expression of the PIM2 gene was analyzed using TaqMan RQ-PCR assay and western blot test. RESULTS: Median PIM2 gene expression in CLL patients was higher than in controls. Patients with high expression of the PIM2 gene had shorter progression-free survival and time to first treatment than patients with low PIM2 expression. It was found that patients with CR had lower expression of the PIM2 gene than patients without complete remission (CR). Notably, associations between high PIM2 expression and rapid lymphocyte doubling time, the percentage of malignant lymphocytes with ZAP70 expression and the Rai stage were revealed. CONCLUSIONS: We found that the PIM2 gene is associated with a more aggressive clinical course of CLL.

Influence of CYP2C19 Genotypes on the Occurrence of Adverse Drug Reactions of Voriconazole among Hematological Patients after Allo-HSCT.

The aim of this study was to determine the influence of different CYP2C19 genotypes on selected liver function parameters, and ADR occurrence during VCZ prophylaxis in adult patients after allo-HSCT (allogeneic hematopoietic stem cell transplantation). CYP2C19 mutations were determined in a cohort of 30 adults using PCR-RFLP methods established by Sim et al. and Goldstein and Blaisdell. The patients' protocol included biometrical and biochemical data, information on the underlying disease, chemotherapy, molds infections occurring during VCZ treatment, adverse drug reactions typical for the use of voriconazole, and probable drug - drug interactions. The observation and reporting of ADR took place from the -1 until the +20th day of VCZ therapy. For statistical analysis the χ2 test was used (p < 0.05). Among the examined patients 23 suffered from at least one side effect during VCZ therapy. Most frequent ADR were gastrointestinal disturbances (n = 15), nervous system (n = 11) and skin (n = 7) disorders. Patients with at least one loss of function allele (*2) were more likely to experience adverse drug reactions than those, with different genotypes. Due to the limited number of patients the result could not be proven with a statistical significance. Previous determination of CYP2C19 genotype may be a useful tool for prevention of adverse drug reactions during VCZ prophylaxis among patients after allo-HSCT.

Elevated serum concentrations of metalloproteinases (MMP-2, MMP-9) and their inhibitors (TIMP-1, TIMP-2) in patients with Graves' orbitopathy.

BACKGROUND: Graves' orbitopathy (GO), also known as thyroid-associated ophthalmopathy, is characterized by dramatic tissue reactivity. Both inflammation and tissue remodeling characterize the clinical course of GO. Some data has been found regarding the association of MMPs and TIMPs in GO. MATERIAL AND METHODS: Serum concentrations of MMP-9, MMP-2, TIMP-1, and TIMP-2 were determined by ELISA method. OBJECTIVES: Forty-eight patients (34 females, 14 males, with median age 51.5 years) with GD and hyperthyroidism were enrolled in the study. In 28 patients, active, moderate-to-severe grade orbitopathy was diagnosed. The aim of this study was to assess the serum concentrations of MMP-2, MMP-9, TIMP-1, and TIMP-2 in patients with Graves' disease (GD), with and without GO, and their relationship with disease severity, as well as to evaluate how these concentrations change after successful treatment. RESULTS: Median serum concentrations of MMP-2 and MMP-9 were significantly higher in all patients with GD as well as in the subgroup with GO than in the control group. Median serum concentrations of TIMP-1 and TIMP-2 were significantly higher in all patients with GD than in controls. The same significant differences were observed in the subgroups with and without GO in comparison with controls. The GO subgroup showed a significant positive correlation between the MMP-9 concentration and the serum level of TSHRAb antibodies, and a clinical activity score ≥4 according to EUGOGO. CONCLUSIONS: In our study we found that only MMP-9 differentiates the patients with and without GO, and may be used as a marker of the disease severity in patients with this manifestation of GD.

Primary Intraocular Diffuse Large B-cell Lymphoma: Diagnostic Difficulties in Deep Retinal Infiltrations with Vitritis.

PURPOSE: Primary intraocular lymphoma (PIOL) is a rare malignancy with an aggressive clinical course. It is usually considered as a subset of primary central nervous system lymphoma. Differential diagnosis should include infectious and non-infectious aetiologies, particularly the common masqueraders sarcoidosis, tuberculosis, viral retinitis and syphilis. PATIENT: The article presents a case of bilateral vitreoretinal lymphoma manifesting as uveitis and vitritis resistant to corticosteroid therapy. The final diagnosis was based on a retinal biopsy. RESULTS: The patient was successfully treated with systemic and local therapy. Long-term complete remission (CR) was reached. The relapse of diffuse large B-cell lymphoma was revealed in the frontal left lobe after 48 months of CR duration. CONCLUSION: The diagnosis of PIOL is always very difficult. Cooperation of pathologists, ophthalmologists and hematologists is required for a quick and accurate diagnosis. Local and systemic treatment is needed to achieve CR, but the relapse rate remains very high.

Elevated PIM2 gene expression is associated with poor survival of patients with acute myeloid leukemia.

The PIM2 gene encodes the serine/threonine kinase involved in cell survival and apoptosis. The aim of the study was to evaluate the expression of the PIM2 gene in acute myeloid leukemia (AML) and to examine its role in apoptosis of the blastic cells. We analyzed the PIM2 expression in 148 patients: 91 with AML, 57 with acute lymphoblastic leukemia and 24 healthy controls by Real-Time PCR and Western blot. Inhibition of the PIM2 gene in human leukemic HL60 cell line was performed with RNAi and apoptosis rate was analyzed. Our results indicate that overexpression of PIM2 in AML is associated with low complete remission rate, high-risk cytogenetics, shorter leukemia-free survival, and event-free survival. Cytometric analysis of HL60/PAC-GFP and HL60/PAC-GFP-shPIM2 cells revealed an increase in the number of apoptotic cells after inhibition of PIM2 gene. In summary, the elevated expression of PIM2 in blastic cells is associated with poor prognosis of AML patients and their resistance to induction therapy.

Increased expression of metalloproteinase-2 and -9 (MMP-2, MMP-9), tissue inhibitor of metalloproteinase-1 and -2 (TIMP-1, TIMP-2), and EMMPRIN (CD147) in multiple myeloma.

INTRODUCTION: Activity of metalloproteinases (MMP) is controlled both by specific tissue inhibitors (TIMP) and activators (extracellular matrix metalloproteinase inducer, EMMPRIN). There are few data available concerning concentration the bone marrow of MMP-2, MMP-9, TIMP-1, and TIMP-2, or EMMPRIM expression by bone marrow mesenchymal stromal cells (BMSCs) in patients with multiple myeloma (MM). PATIENTS AND METHODS: We studied 40 newly diagnosed, untreated patients: 18 males and 22 females with de novo MM and 11 healthy controls. Bone marrow was collected prior to therapy. BMSCs were derived by culturing bone marrow cells on MesenCult. Protein concentrations were determined in bone marrow plasma and culture supernatants by ELISA. EMMPRIN expression by BMSCs was assessed by flow cytometry. RESULTS: The median concentrations of MMP-9, TIMP-1, and TIMP-2 in both marrow plasma and culture supernatants were significantly higher in MM patients than controls. CONCLUSION: EMMPRIN expression and ratios MMP-9/TIMP-1 and MMP-2/TIMP-2 were higher in MM patients, our results demonstrate that in MM patients MMP-2 and MMP-9 are secreted in higher amounts and are not balanced by inhibitors.

The Hasford Score May Predict Molecular Response in Chronic Myeloid Leukemia Patients: A Single Institution Experience.

The Sokal, Hasford, and EUTOS scores were established in different treatment eras of chronic myeloid leukemia (CML). None of them was reported to predict molecular response. In this single center study we tried to reevaluate the usefulness of three main scores in TKI era. The study group included 88 CML patients in first chronic phase treated initially with standard imatinib dose. All of them achieved major molecular response (MMR) in time points defined by European LeukemiaNet (ELN). 42 patients lost MMR in a median time of 47 months and we found a significant difference in MMR maintenance between intermediate-risk (IR) and low-risk (LR) patients assessed by Hasford score. All 42 patients were switched to second-generation TKI (2G-TKI) treatment. At 18 months of 2G-TKI therapy we have still found a significant difference in BCR-ABL transcript levels and MMR rate between IR and LR groups. We did not find any of the described differences discriminating patients by Sokal or EUTOS score. In this retrospective single center analysis we found Hasford score to be useful in predicting molecular response in first chronic phase of CML patients.

Mycotic Infections of the Eye.

Fungal infections of the eye are an important cause of significant visual loss and blindness in some regions of the world, especially developing countries. Ocular mycoses remain a diagnostic and therapeutic challenge to the ophthalmologist. Corneal infection is the most frequent presentation, but the orbit, eyelids, lacrimal apparatus, conjunctiva, sclera and internal structures of the eye can also be affected. Candida spp., Fusarium spp. and Aspergillus spp. are the most frequently isolated organisms in fungal keratitis and in endophthalmitis. The difficulties posed by ocular mycoses are mainly related to establishing the clinical diagnosis, isolation of the fungal pathogen and effective local treatment, particularly in infections of the cornea. The critical issue in diagnosing fungal infection of the eye is microbiological identification of the etiologic agent in clinical samples. Early diagnosis and prompt treatment allow serious complications, including blindness, to be avoided. Local, systemic and even surgical treatment is applied in the therapy.

The use of hyperbaric oxygen therapy in the treatment of hemorrhagic cystitis after allogeneic stem cell transplantation from an unrelated donor.

Hemorrhagic cystitis (HC) is a diffuse inflammation of the bladder of an infectious or non-infectious etiology, causing bleeding of the bladder mucosa. There are no explicit guidelines defining the appropriate treatment of HC. Hyperbaric oxygen therapy (HBO) is a non-invasive method involving the use of 100 % oxygen under increased pressure, which penetrates to poorly perfused areas. The most appropriate group for treatment with HBO is patients with BK virus-associated HC after allogenic human stem cell transplantation (alloHSCT). In this report, we present five patients after alloHSCT from a matched unrelated donor with symptoms of HC successfully treated with HBO. All patients received therapy with 100 % oxygen in a hyperbaric chamber at 2.5 atmospheres for 60 min, delivered 5 days per week. Complete response with resolution of pain and hematuria, as well as eradication of viral load, was achieved by all the patients after a mean of 13 sessions (range 11-30) of HBO. These data indicate that HBO therapy is sufficient and effective in the treatment of HC, and represents a well-tolerated procedure with good clinical and laboratory results after ineffective primary treatment.