Is an earlier strategy for harvesting peripheral blood stem cells in healthy allogeneic donors feasible?

INTRODUCTION: Peripheral blood stem cells (PBSC) mobilization with granulocyte colony stimulating factor (G-CSF) for healthy donors is generally performed at 5th day. However, earlier collection is sometimes feasible, raising the question of whether to initiate apheresis early to limit further G-CSF exposure, while considering the risk of mobilization failure. In the current study, we examined the factors predicting successful 4th day collection and developed a model that can be used practically. PATIENTS AND METHODS: The study was carried out by obtaining the data of PBSC mobilizations performed between January 2009 and September 2022 in our transplantation center. RESULTS: A total of 141 healthy donors with a median donor age of 32 (18-64) were included. Adequate mobilization was achieved in 115 (81.6 %) patients. Median peripheral CD34 + cell count was 69.4/µL in the adequate mobilization group and 46/µL in the mobilization failure group (p < 0001). Multivariate analysis revealed that donor/recipient weight ratio and the 4th day peripheral CD34 + cell count≥ 50/µL were independent markers for 4th day collection success. A predictive model of our center including these parameters was available with 0.765 sensitivity and 0.968 specificity [(AUC):0.948 (95 % CI, 0.90-0.99), p < 0.001]. CONCLUSION: The result of the current study shows that peripheral 4th day collection can be performed in selected donors, taking into account peripheral CD34+ cell count and donor/recipient weight ratio. In addition, using these indicators, new predictive models can be created that may assist clinicians in daily practice.

International Forum: The Turkish perspective on apheresis activity: The Turkish apheresis registry report.

Therapeutic apheresis is an extracorporeal treatment that selectively removes abnormal cells or harmful substances in the blood that are associated with or cause certain diseases. During the last decades the application of therapeutic apheresis has expanded to a broad spectrum of hematological and non-hematological diseases due to various studies on the clinical efficacy of this procedure. In this context there are more than 30 centers performing therapeutic apheresis and registered in the apheresis database in Turkey. Herein, we, The Turkish Apheresis Registry, aimed to analyze some key articles published so far from Turkey regarding the use of apheresis for various indications.

The outcome of COVID-19 in patients with hematological malignancy.

In this study, we aim to report the outcomes for COVID-19 in patients with hematological malignancy in Turkey. Data from laboratory-confirmed 188 897 COVID-19 patients diagnosed between 11 March 2020 and 22 June 2020 included in the Republic of Turkey, Ministry of Health database were analyzed retrospectively. All COVID-19 patients with hematological malignancy (n = 740) were included in the study and an age, sex, and comorbidity-matched cohort of COVID-19 patients without cancer (n = 740) at a 1:1 ratio was used for comparison. Non-Hodgkin lymphoma (30.1%), myelodysplastic syndrome (19.7%), myeloproliferative neoplasm (15.7%) were the most common hematological malignancies. The rates of severe and critical disease were significantly higher in patients with hematological malignancy compared with patients without cancer (P = .001). The rates of hospital and intensive care unit (ICU) admission were higher in patients with hematological malignancy compared with the patients without cancer (P = .023, P = .001, respectively). The length of hospital stay and ICU stay was similar between groups (P = .7, P = .3, retrospectively). The rate of mechanical ventilation (MV) support was higher in patients with hematological malignancy compared with the control group (P = .001). The case fatality rate was 13.8% in patients with hematological malignancy, and it was 6.8% in the control group (P = .001). This study reveals that there is an increased risk of COVID-19-related serious events (ICU admission, MV support, or death) in patients with hematological malignancy compared with COVID-19 patients without cancer and confirms the high vulnerability of patients with hematological malignancy in the current pandemic.

Does myeloma genetic have an effect on stem cell mobilization?

BACKGROUND: Autologous stem cell transplantation (ASCT) after induction treatment is the standard of care. Our understanding of myeloma genetics has been very limited and its effect to stem cell mobilization is not widely investigated. We aimed to investigate the effect of genetic abnormalities on stem cell mobilization in myeloma. METHODS: The data of 150 MM patients who underwent stem cell mobilization at our center between 2009-2020 were included and analyzed retrospectively. Pre-treatment bone marrow cytogenetics and fluorescence in situ hybridization tests were performed for each patient. RESULTS: Groups were divided into two as patients with normal cytogenetic and abnormal cytogenetic. No difference observed between groups regarding age, gender and ECOG (p = 0.4; p = 0.2; p = 0.3). Groups were similar concerning myeloma characteristics, received treatment and treatment response. Median CD34+ cells/kg harvested was 444(2-11.29) in normal cytogenetic group whereas it was 4,8(2.4-8.6) in abnormal cytogenetic group(p = 0.2). Optimal CD34+ cells level achievement was 73 (67 %) in normal cytogenetic group while it was 25(71.4 %) in abnormal cytogenetic group(p = 0.6). Neutrophil and platelet engraftment durations were similar among cytogenetic groups (p = 0.7; p = 0.9). R-ISS based groups were also did not differ regarding harvested CD34+ cells and achievement optimal CD34 level (p = 0.79, p = 0.74). Engraftment durations for neutrophil and platelet were comparable between R-ISS based groups (p = 0.59, p = 0.65) CONCLUSIONS: Here we were not able to find any impact of genetic abnormalities on stem cell mobilization in myeloma patients. Expanded studies can aid to identify the effect of particular genetic anomalies on the stem cell mobilization.

Mesenchymal stem cell transfusion: Possible beneficial effects in COVID-19 patients.

SARS-CoV-2 attaches to the angiotensin-converting enzyme 2 (ACE-2) receptor on human cells. The virus causes hypercytokinemia, capillary leak, pulmonary edema, acute respiratory distress syndrome, acute cardiac injury, and leads to death. Mesenchymal stem cells (MSCs) are ACE-2 negative cells; therefore, can escape from SARS-CoV-2. MSCs prevent hypercytokinemia and help the resolution of the pulmonary edema and other damages occurred during the course of COVID-19. In addition, MSCs enhance the regeneration of the lung and other tissues affected by SARS-CoV-2. The case series reported beneficial effect of MSCs in COVID-19 treatment. However, there are some concerns about the safety of MSCs, particularly referring to the increased risk of disseminated intravascular coagulation, and thromboembolism due to the expression of TF/CD142. Prospective, randomized, large scale studies are needed to reveal the optimum dose, administration way, time, efficacy, and safety of MSCs in the COVID-19 treatment.

Old is bad? The effect of age on peripheral stem cell mobilization and transplantation outcomes.

INTRODUCTION: Allogeneic stem cell transplantation (Allo-SCT) is a well-established treatment option for hematological malignancies. With the introduction of reduced-intensity conditioning regimens (RIC) and better supportive measures the elderly are able to receive Allo-SCT. A considerable number of patients are elderly, and often their HLA matched sibling donor is elderly, moreover. Here, we aim to explore the effect of donors' age on stem cell harvesting, engraftment duration after Allo-SCT, and product quality. METHOD: Sixty-one healthy allogeneic stem cell donors aged 50 years and older who underwent stem cell mobilization at our center between 2009-2019 were enrolled for the study. All donors received 4-5 days of G-CSF, mostly filgrastim or lenograstim and their biosimilar equivalents were given subcutaneously as a total dose of 10 mcg/kg/day. Groups were separated into three groups as aged 50-54 group A, 55-59 group B, aged 60 and older group C. RESULTS: Pre-apheresis peripheral blood CD34+ count was similar all groups (p = 0.2). One day apheresis was sufficient for 72.7 % of group A, 27.3 % for group B and 47.1 % for group C (p = 0.02). Total harvested CD34+ cells were comparable among groups (p = 0.5). CONCLUSION: Adequate stem cell harvest in older donors is feasible. Older donors may require more than one apheresis procedure and generally procedure was well tolerated. When assessing donors, age should represent less significance.

Convalescent plasma therapy in patients with COVID-19.

INTRODUCTION: Passive antibody therapy has been used to immunize vulnerable people against infectious agents. In this study, we aim to investigate the efficacy of convalescent plasma (CP) in the treatment of severe and critically ill patients diagnosed with COVID-19. METHOD: The data of severe or critically ill COVID-19 patients who received anti-SARS-CoV-2 antibody-containing CP along with the antiviral treatment (n = 888) and an age-gender, comorbidity, and other COVID-19 treatments matched severe or critically ill COVID-19 patients at 1:1 ratio (n = 888) were analyzed retrospectively. RESULTS: Duration in the intensive care unit (ICU), the rate of mechanical ventilation (MV) support and vasopressor support were lower in CP group compared with the control group (p = 0.001, p = 0.02, p = 0.001, respectively). The case fatality rate (CFR) was 24.7 % in the CP group, and it was 27.7 % in the control group. Administration of CP 20 days after the COVID-19 diagnosis or COVID-19 related symptoms were associated with a higher rate of MV support compared with the first 3 interval groups (≤5 days, 6-10 days, 11-15 days) (p=0.001). CONCLUSION: CP therapy seems to be effective for a better course of COVID-19 in severe and critically ill patients.

Gemcitabine, dexamethasone and cisplatin (GDP) is an effective and well-tolerated mobilization regimen for relapsed and refractory lymphoma: a single center experience

Background/aim: Gemcitabine, dexamethasone and cisplatin (GDP) is a well-established salvage regimen for relapsed and refractory lymphomas. In this study, we aimed to share our experience with the patients who received GDP/R-GDP (rituximab-gemcitabine, dexamethasone and cisplatin) for stem cell mobilization. Materials and methods: Data of 69 relapsed and refractory Hodgkin lymphoma (HL) and Non-Hodgkin lymphoma (NHL) patients who received GDP/R-GDP as salvage chemotherapy in our center between July 2014 and January 2020 were retrospectively evaluated. After the evaluation of response, 52 patients had a chemosensitive disease and underwent mobilization with GDP/R-GDP plus G­CSF (granulocyte colony-stimulating factor). Collected CD34+ stem cells and related parameters were compared in terms of diagnosis of HL and NHL, early and late stage, patients who did not receive RT and those who received RT, and patients aged under 60 and over 60. Results: On the 15th day on average (range 11­20), a median number of 8.7 × 106 /kg (4.1­41.5) CD34+ stem cells were collected in 51 (98%) of our 52 chemosensitive patients and 1 (2%) patients failed to mobilize. We observed acceptable hematological and nonhematological toxicity. The targeted amount of 2 × 106 /kg CD34+ stem cells was attained by 98% (n: 51) patients, and all of them underwent autologous stem cell transplantation. Moreover, low toxicity profiles provide outpatient utilization option clinics with close follow-up and adequate supportive care. Conclusion: We suggest that GDP/R-GDP plus G-CSF can be used as an effective chemotherapy regimen for mobilizing CD34+ stem cells from peripheral blood in relapsed and refractory lymphoma patients due to low toxicity, effective tumor reduction, and successful stem cell mobilization. It can also be assumed that the GDP mobilization regimen may be more effective, especially in patients with early-stage disease and in HL patients.

COVID-19 clinical course and blood groups: Turkish population-based study

Background/aim: SARS-CoV-2 enters the cell through the binding of the S glycoprotein on the surface of the virus to the angiotensin- converting enzyme 2 (ACE-2) in the host cells and also SARS-CoV S protein binding to ACE-2 was inhibited by anti-A antibodies. The aim of the study was to investigate the relationship between blood groups and the course of COVID-19 in Turkey. Materials and methods: Laboratory confirmed COVID-19 patients aged 18 and over (n = 39.850) were randomized in age and sex- matched groups according to blood groups. Results: Advanced age, male sex and blood group A were found to be related with increased rate of intensive care unit (ICU) admission (OR = 1.089, 95% CI: 1.085­1.093 for age; OR = 1.963, 95% CI: 1.737­2.218 for male sex; OR = 1.216, 95% CI: 1.023­1.446 for blood group A). When blood group O individuals were compared to non-O individuals, no significant difference was observed regarding the rate of hospital and ICU admission, mechanical ventilation (MV) support, length of hospital and ICU stay, and case fatality rate (CFR). The CFR in patients with blood group A, B, O, and AB were 2.6%, 2.2%, 3.1%, and 2.3%, respectively. There were no significant differences between Rh-negative and positive patients regarding the rate of hospital and ICU admission (p = 0.280 and p = 0.741, respectively), also the rate of MV support and CFR was similar (p = 0.933 and p = 0.417). Conclusion: Our study revealed that ABO and Rh blood groups do not have any impact on the rate of hospital admission, hospital and ICU stay, MV support, and CFR.

The effect of serum vitamin B12, folate, ferritin levels and transferrin saturation on stem cell mobilization in allogeneic donors.

INTRODUCTION: Peripheric blood derived stem cells are used in 75 % of allogeneic stem cell transplantations. Iron, vitamin B12 and folate involve in hematopoiesis. Therefore serum levels of iron, vitamin B12 and folat may effect stem cell mobilization. We aimed to analyze the effects of iron status, vitamin B12 and folate levels on peripheric blood stem cell mobilization in healthy donors. METHOD: The mobilization results of 218 allogeneic donors were analyzed retrospectively. RESULTS: In 64 donors, serum ferritin level was <15 µg / L and transferrin saturation was <20 %. When we compared the donors with iron deficiency to the donors without iron deficiency, the number of collected CD34 + cell was significantly higher in donors without iron deficiency. We did not find any impact of serum vitamin B12 and folate level on CD34+ cells collected. CONCLUSION: Our study shows that serum ferritin and transferrin saturation have a greater effect on the amount of CD34+ cells collected from donors than serum vitamin B12 and folate levels. Consequently, when compliance tests of allogeneic donors are performed, the evaluation of vitamin B12 and folate levels is not necessary; whereas iron deficiency must be assessed and -if possible- corrected before apheresis is performed.

Inferior prognosis in poor mobilizing myeloma patients.

INTRODUCTION: Induction treatment followed by autologous stem cell transplantation (ASCT) has been accepted as the standard treatment for multiple myeloma (MM) patients. Granulocyte colony stimulating agent (G-CSF), chemotherapy or agents likes plerixafor are being used for the mobilization of stem cells from bone marrow. In this study, we evaluated the impact of the mobilization methods on the outcome of MM patients after ASCT. METHOD: The data of 205 MM patients who underwent ASCT at our center between December 2009 and January 2019 were retrospectively analyzed. Patients were divided into 2 groups as good mobilizers (patients who were mobilized with G-CSF alone) and poor mobilizers (patients who were failed to mobilize with G-CSF alone and mobilized with G-CSF + cylophosphomide or G-CSF + plerixafor). RESULTS: The median progression free survival (PFS) was 18.27 ± 3.22 months in good mobilizers and 14.22 ± 3.7 months in poor mobilizers. In G-CSF + cyclophosphamide method median PFS was 15.4 ± 4.9 months wheras it was only 4 months in G-CSF + plerixafor method. We did not find a statistically significant difference between good and poor mobilizers regarding median PFS (p: 0.342). The median overall survival (OS) was found 34.48 ± 4.2 months in good mobilizers and 15.13 ± 5.78 months in poor mobilizers. In G-CSF + cyclophosphamide method median OS was 17 ± 14.01 months wheras it was 10.66 ± 7.68 months in G-CSF + plerixafor method. We found a statistically significant difference between good and poor mobilizers regarding median OS (p: 0.007*). CONCLUSION: Our study shows that difficulty in stem cell mobilization is correlated with worse outcome.

Outcome of COVID-19 in patients with chronic myeloid leukemia receiving tyrosine kinase inhibitors.

INTRODUCTION: In this study, we aim to report the outcome of COVID-19 in chronic myeloid leukemia (CML) patients receiving tyrosine kinase inhibitor (TKI). METHOD: The data of 16 laboratory-confirmed COVID-19 patients with CML receiving TKI and age, gender, and comorbid disease matched COVID-19 patients without cancer at a 3/1 ratio (n = 48), diagnosed between March 11, 2020 and May 22, 2020 and included in the Republic of Turkey, Ministry of Health database, were analyzed retrospectively. RESULTS: The rates of intensive care unit (ICU) admission, and mechanical ventilation (MV) support were lower in CML patients compared to the control group, however, these differences did not achieve statistical significance (p = 0.1, and p = 0.2, respectively). The length of hospital stay was shorter in CML patients compared with the control group; however, it was not statistically significant (p = 0.8). The case fatality rate (CFR) in COVID-19 patients with CML was 6.3%, and it was 12.8% in the control group. Although the CFR in CML patients with COVID-19 was lower compared to the control group, this difference did not achieve statistical significance (p = 0.5). When CML patients were divided into 3 groups according to the TKI, no significant difference was observed regarding the rate of ICU admission, MV support, CFR, the length of stay in both hospital and ICU (all p > 0.05). CONCLUSION: This study highlights that large scale prospective and randomized studies should be conducted in order to investigate the role of TKIs in the treatment of COVID-19.

The effect of gemcitabine, dexamethasone, and cisplatin chemotherapy in relapsed/refractory NHL and HL patients: A single center experience.

The optimal choice of salvage therapy for patients with relapsed/refractory non-Hodgkin lymphoma or Hodgkin lymphoma remains controversial. In this study, we aimed to share our experience in relapsed/refractory lymphoma patients who received GDP/R-GDP as salvage chemotherapy in our center. Data of 47 relapsed/refractory Hodgkin lymphoma and non-Hodgkin lymphoma patients who received GDP or R-GDP as salvage chemotherapy in our center between July 2014 and October 2017 were retrospectively evaluated. Non-Hodgkin lymphoma and Hodgkin lymphoma patients were divided into two groups as primary refractory and relapsed. The one-year overall survival was 100% (for relapsed) and 36.9% (for refractory) in the non-Hodgkin lymphoma groups, and 82.5% (for relapsed) and 80% (for refractory) in the Hodgkin lymphoma group. The one-year progression-free survival (PFS) was 72.7% (for relapsed) and 38.5% (for refractory) in patients with NHL, and 41% (for relapsed) and 18.2% (for refractory) in patients with HL. GDP/R-GDP seems to be a well-tolerated out-patient salvage regimen for relapsed/refractory non-Hodgkin lymphoma and Hodgkin lymphoma. Although proven efficacy, negative toxicity profile, and ease of administration, the application of gemcitabine-based therapy for patients with primary refractory non-Hodgkin lymphoma and Hodgkin lymphoma provided limited success.

The effect of high-dose cytarabine followed by autologous hematopoietic stem cell transplantation on the outcome of patients with mantle cell lymphoma.

INTRODUCTION: The aim of this study was to investigate the influence of high-dose cytosine arabinoside (HDAC)-containing treatments followed by autologous hematopoietic stem cell transplantation on the survival of patients with mantle cell lymphoma. MATERIAL AND METHODS: The data of 27 MCL patients who were followed-up between January 2009 and December 2015 were analyzed retrospectively. RESULTS: The median age of the patients was 63 (range, 45-82) with 22 (81.4%) males and 5 (18.6%) females. Eight of 27 patients were treated with HDAC-containing regimens either as induction or salvage chemotherapy followed by autologous hematopoietic stem cell transplantation (AHSCT). The patients who received HDAC-containing regimen followed by AHSCT were found to have better one-year survival compared to others (p = 0.03). Median follow-up of patient cohort was 27.6 months and median overall survival (OS) was not reached. The probability of one-year OS for all patients was 76.8%. CONCLUSION: Our findings suggest that HDAC treatment followed by AHSCT seems to provide the best outcome for young-fit patients presenting with mantle cell lymphoma.

Evaluation of neutropenia-related outcomes in Hodgkin's lymphoma patients with moderate or severe neutropenia who received ABVD chemotherapy without using granulocyte-colony stimulating factor.

OBJECTIVE: To evaluate the possible neutropenia-related effects of administering adriamycin [doxorubicin], bleomycin, vinblastin, dacarbazine (ABVD) chemotherapy in Hodgkin's lymphoma patients with moderate or severe neutropenia without granulocyte-colony stimulating factor supplementation. METHODS: This study evaluated neutropenia-related outcomes and the need for granulocyte-colony stimulating factor use during the periods between chemotherapy rounds. Forty-three rounds of ABVD chemotherapy were evaluated in the study. The outcomes that could be related to neutropenia were analyzed. In addition, rounds of ABVD chemotherapy given in the presence of severe neutropenia were compared with ABVD chemotherapy rounds given in the presence of moderate neutropenia in terms of neutropenia-related outcomes and the need for granulocyte-colony stimulating factor use. The study only included patients with classical Hodgkin's disease (lymphoma). Patients with a final neutrophil count of <1 × 103 cells/µL (<1000 cells/µL) prior to chemotherapy round and those receiving ABVD chemotherapy for Hodgkin's lymphoma were included in the study. RESULTS: We observed that none of the patients with moderate neutropenia before the start of chemotherapy round needed granulocyte-colony stimulating factor, and four patients with severe neutropenia prior to the start of chemotherapy round required granulocyte-colony stimulating factor. However, there was no statistically significant relationship between the severity of neutropenia (in terms of moderate and severe) before chemotherapy and granulocyte-colony stimulating factor requirement after chemotherapy (p> 0.05). Furthermore, none of the patients included in the study had bleomycin-related lung toxicity during the treatment periods included in the study. CONCLUSION: Administering ABVD chemotherapy to patients with moderate neutropenia seems to be safe.

The effect of pre-conditioning immunoglobulin and absolute lymphocyte count on the outcomes of allogeneic hematopoietic cell transplantation.

INTRODUCTION: The prevention of mortality and morbidity related to the increasingly used allogeneic hematopoietic cell transplantation (allo-HCT), along with the effects of pre- and post-transplant immune status on transplant outcomes, have become the focus of the studies conducted on this subject in recent years. In parallel, this study was designed to investigate the effects of pre-conditioning immunoglobulin (pre-conditioning-Ig) and pre-conditioning absolute lymphocyte count (pre-conditioning-ALC) levels on transplant outcomes. METHODS: This study was designed as a retrospective, observational and cross-sectional study. The objective of the study is to investigate the effects of pre-conditioning-Ig and ALC levels primarily on the rate of patients with febrile neutropenia (FEN) and the duration of FEN and length of hospital stay (LoS), and secondarily on acute graft-versus-host disease (aGVHD), cytomegalovirus (CMV) viremia, and mortality in the acute leukemia patients who underwent allo-HCT. RESULTS: A total of 104 acute leukemia patients, of whom 55 had acute lymphoblastic leukemia (ALL) and 49 had acute myeloid leukemia (AML), were included in the study. Compared to the AML group, the median pre-conditioning-IgG, IgA, and IgM levels were found to be significantly lower in the ALL group (11.3 vs. 6.6, p < 0.001; 1.8 vs. 0.9, p < 0.001; and 0.7 vs. 0.4, p < 0.001; respectively). But, there was no significant difference between the groups in pre-conditioning-Ig and ALC levels and transplant outcomes. However, subgroup analysis revealed that high pre-conditioning-ALC levels were significantly correlated with aGVHD levels (Odds Ratio: 1.02; p = 0.034) and low pre-conditioning-IgM levels were significantly correlated with increased mortality rate (Hazard Ratio: 0.08; p = 0.042) in AML patients. CONCLUSION: The significant difference determined between the ALL and AML groups in pre-conditioning-Ig levels was not reflected on the effects of pre-conditioning-Ig and ALC levels on transplant outcomes. However, we observed that pre-conditioning-IgM and ALC levels have an impact on transplant outcomes in AML patients.

Real-world data on the effectiveness and safety of Ixazomib-Lenalidomide-Dexamethasone therapy in relapsed/refractory multiple myeloma patients: a multicenter experience in Turkey.

A multicenter, retrospective, observational study was conducted to explore effectiveness and safety of ixazomib plus lenalidomide with dexamethasone (IRd) in relapsed/refractory multiple myeloma (RRMM) patients following at least ≥ two lines of therapy. Patients' treatment responses, overall response rate, progression-free survival rate, and adverse events were recorded. Mean age of 54 patients was 66.5 ± 9.1 years. There were 20 patients (37.0%) with progression. Median progression-free survival was 13 months in patients who received a median of three therapy lines in a 7.5-month follow-up period. Overall response rate was 38.5%. Of 54 patients, 19 (40.4%) had at least one adverse event, and nine (19.1%) had an adverse event of at least grade 3 or more. Of 72 adverse events observed in 47 patients, 68% were grade 1 or 2. Treatment was not stopped in any patient due to adverse events. IRd combination therapy was effective and safe in heavily treated RRMM patients.

Single-Dose Rasburicase Might Be Adequate To Overcome Tumor Lysis Syndrome In Hematological Malignancies.

INTRODUCTION: Tumor lysis syndrome (TLS) is a commonly observed oncological emergency that requires prompt diagnosis and treatment. Rasburicase is a recombinant urate oxidase endorsed in TLS for the treatment of hyperuricemia. The effect of single-dose 7.5 mg rasburicase at longer follow-ups was not widely investigated. PATIENTS AND METHODS: Eighty-two patients included in the study with clinical TLS and laboratory TLS. The primary endpoint was the normalization of uric acid (<6mg/dL) within 24 hours of rasburicase administration, which was described as treatment success. The secondary endpoint was defined as having sustained response at the first week. The third endpoint was defined as the reaching the baseline renal function before TLS. RESULTS: We found that the use of a 7.5 mg dose of rasburicase controlled uric acid in 74 of 82 (90,2%) patients at the 24th hour. In the first week, uric acid remained at normal levels in 69 of 82 (84,1%) patients. At 24 hours, the TLS risk group was the only predictor for failing uric acid normalization; at the end of the first week, no predictive factor was identified for failing uric acid normalization. CONCLUSION: Rasburicase at 7.5 mg dose is an important agent for controlling laboratory and clinical TLS at 24 hours and extending its effect to the first week.