Tumor lysis syndrome in induction therapy for acute myeloid leukemia before the rasburicase era.

Guidelines recommend rasburicase for high-risk patients to prevent tumor lysis syndrome (TLS). However, little information is available on the incidence and outcome of TLS in AML patients. We analyzed 145 patients with AML who underwent induction therapy before the approval of rasburicase to evaluate the incidence of TLS and the necessity of rasburicase as prophylaxis. Three patients had already developed clinical TLS (CTLS) at diagnosis of AML, and another three developed CTLS after the initiation of chemotherapy. In patients without TLS at diagnosis of AML, the risk for developing TLS was classified as high in 44 patients, intermediate in 41 and low in 57, according to the current guidelines. Allopurinol alone was administered to prevent hyperuricemia in all patients. All three patients who developed CTLS after diagnosis of AML were at high risk of TLS, and had elevated serum creatinine levels and a WBC count greater than 200,000 per microliter at diagnosis of AML. Allopurinol may be insufficient to prevent TLS in high-risk patients with renal dysfunction at diagnosis of AML, especially those with a high tumor burden and a WBC count of 200,000 or more, which indicates that prophylactic administration of rasburicase should be considered.

Treatment with Rasburicase in Hospitalized Patients with Cardiorenal Syndrome: Old Treatment, New Scenario.

Cardiorenal syndrome (CRS) involves joint dysfunction of the heart and kidney. Acute forms share biochemical alterations like hyperuricaemia (HU) with tumour lysis syndrome (TLS). The mainstay treatment of acute CRS with systemic overload is diuretics, but rasburicase is used in TLS to prevent and treat hyperuricaemia. An observational, retrospective study was performed to assess the effectiveness and safety of a single dose of rasburicase in hospitalized patients with cardiorenal syndrome, worsening renal function and uric acid levels above 9 mg/dL. Rasburicase improved diuresis and systemic congestion in the 35 patients included. A total of 86% of patients did not need to undergo RRT, and early withdrawal was possible in the remaining five. Creatinine (Cr) decreased after treatment with rasburicase from a peak of 3.6 ± 1.27 to 1.79 ± 0.83 mg/dL, and the estimated glomerular filtration rate (eGFR) improved from 17 ± 8 to 41 ± 20 mL/min/1.73 m2 (p = 0.0001). The levels of N-terminal type B Brain Natriuretic Peptide (Nt-ProBNP) and C-reactive protein (CRP) were also significantly reduced. No relevant adverse events were detected. Our results show that early treatment with a dose of rasburicase in patients with CRS and severe HU is effective to improve renal function and systemic congestion, avoiding the need for sustained extrarenal clearance, regardless of comorbidities and ventricular function.

Laboratory and clinical features of tumor lysis syndrome in children with non-Hodgkin lymphoma and evaluation of long-term renal functions in survivors.

OBJECTIVE: The purpose of our study is to investigate the laboratory and clinical features of tumor lysis syndrome (TLS) and acute kidney injury (AKI) in childhood non-Hodgkin lymphomas (NHL) and to reveal their impact on long term kidney function in survivors. METHODS: Our single-center retrospective study included 107 patients (0-18 years old) with NHL who were admitted and treated at our hospital between 1998 and 2020. The relationship between TLS and age, gender, histopathological subgroup, tumor stage, lactate dehydrogenase (LDH) level at presentation, bone marrow and kidney involvement were assessed. The long-term renal functions of the patients were investigated. RESULTS: 80.3% of the patients were male with a median age of 9.8 years. The most common detected histopathological subgroup was Burkitt lymphoma. Hyperhydration with or without alkalinisation, and allopurinol were used in first-line treatment and prophylaxis of TLS. Laboratory TLS and clinical TLS was observed in 30.8% and 12.1% of patients, respectively. A significant correlation was found between young age, advanced stage, high LDH level at presentation, and TLS. AKI was observed in 12.1% of the patients. When the glomerular filtration rate values of the patients at the first and last admissions were compared after an average of 6.9 years, a mean decrease of 10 mL/min/1.73 m2 was found. It was not, however, found to be statistically significant. CONCLUSION: Lower age, advanced stage, and high LDH level at presentation were found to be risk factors for TLS in our study. Long-term renal function loss was not observed in the survivors who received early and careful prophylaxis/treatment for TLS. The survivors are still being followed up.

Venetoclax plus low-dose cytarabine in patients with newly diagnosed acute myeloid leukemia ineligible for intensive chemotherapy: an expanded access study in Japan.

BACKGROUND: In a Phase 3 international clinical trial (VIALE-C), venetoclax plus low-dose cytarabine improved the response rate and overall survival versus placebo plus low-dose cytarabine in patients with newly diagnosed acute myeloid leukemia who were ineligible for intensive chemotherapy. After the enrollment period of VIALE-C ended, we conducted an expanded access study to provide preapproval access to venetoclax in combination with low-dose cytarabine in Japan. METHODS: Previously, untreated patients with acute myeloid leukemia who were ineligible for intensive chemotherapy were enrolled according to the VIALE-C criteria. Patients received venetoclax (600 mg, Days 1-28, 4-day ramp-up in Cycle 1) in 28-day cycles and low-dose cytarabine (20 mg/m2, Days 1-10). All patients took tumor lysis syndrome prophylactic agents and hydration. Safety endpoints were assessed. RESULTS: Fourteen patients were enrolled in this study. The median age was 77.5 years (range = 61-84), with 78.6% over 75 years old. The most common grade ≥ 3 treatment-emergent adverse event was neutropenia (57.1%). Febrile neutropenia was the most frequent serious adverse event (21.4%). One patient developed treatment-related acute kidney injury, leading to discontinuation of treatment. Two patients died because of cardiac failure and disease progression that were judged not related to study treatment. No patients developed tumor lysis syndrome. CONCLUSIONS: The safety outcomes were similar to those in VIALE-C without new safety signals and were well managed with standard medical care. In clinical practice, more patients with severe background disease are expected, in comparison with in VIALE-C, suggesting that it is important to carefully manage and prevent adverse events.

Successful Prevention of Tumour Lysis Syndrome in HER2-positive Breast Cancer: Case Report and Literature Review.

BACKGROUND/AIM: Tumour lysis syndrome (TLS) is a life-threatening oncological emergency. TLS is rare and associated with a higher mortality rate in solid tumours than in haematological malignancies. Our case report and literature review aimed to identify the distinctive features and hazards of TLS in breast cancer. CASE REPORT: A 41-year-old woman complained of vomiting and epigastric pain and was diagnosed with HER2-positive, hormone-receptor-positive breast cancer with multiple liver and bone metastases and lymphangitis carcinomatosis. She had several risk factors for TLS: high tumour volume, high sensitivity to antineoplastic treatment, multiple liver metastases, high lactate dehydrogenase levels, and hyperuricaemia. To prevent TLS, she was treated with hydration and febuxostat. One day after the first course of trastuzumab and pertuzumab, she was diagnosed with disseminated intravascular coagulation (DIC). After 3 further days of observation, she was relieved of DIC and administered a reduced dose of paclitaxel without life-threatening complications. The patient achieved a partial response after four cycles of anti-HER2 therapy and chemotherapy. CONCLUSION: TLS in solid tumours is a lethal situation and can be complicated by DIC. Early recognition of patients who are at risk of TLS and initiation of therapy is essential to avoid fatal situations.

CE: Tumor Lysis Syndrome: An Oncologic Emergency.

ABSTRACT: Tumor lysis syndrome is an oncologic emergency caused by the release of intracellular material, such as potassium, phosphate, and nucleic acids, into the bloodstream from the disintegration (lysis) of tumor cells. This condition, which is characterized by electrolyte imbalances, can be life-threatening, causing arrhythmias, seizures, acute kidney injury, and multiple organ failure. The prevention and treatment of tumor lysis syndrome requires immediate recognition of patients at risk for its development. With this knowledge, nurses can better manage and monitor treatments, thereby preventing complications and achieving better patient outcomes.

Evaluation of an interdisciplinary venetoclax initiation process in minimizing risk of tumor lysis syndrome.

Venetoclax is a BCL-2 inhibitor approved for treatment of adult patients with chronic lymphocytic leukemia (CLL). Due to significant risk of tumor lysis syndrome (TLS) upon treatment initiation, a 5-week dose ramp-up is recommended. University of North Carolina Medical Center (UNCMC) utilizes a novel interdisciplinary model of care involving clinical pharmacists (CPs) who oversee the 5-week ramp-up to minimize treatment-related adverse events. The aim of this study was to investigate the effects of a pharmacist-led venetoclax initiation protocol on patient outcomes. The primary objective was to determine the incidence of venetoclax-induced TLS during dose ramp-up in patients managed by a CP. In this cohort (n = 39), there were no cases of TLS during the venetoclax ramp-up. Reduced TLS rates were observed in CP-managed real-world patients compared to previous real-world reports. This real-world analysis supports the utilization of CPs for intensive monitoring of patients initiated on venetoclax.

[Tumor Lysis Syndrome-Up to Date].

Tumor lysis syndrome(TLS)is an oncologic emergency resulting from the lysis of large numbers of cancer cells leading to metabolic abnormalities when their contents are released into the bloodstream. TLS is sometimes fatal, and prevention is the cornerstone of TLS countermeasures. In 2010, Cairo et al reported the TLS development risk by cancer type after conventional chemotherapy. However, recently developed drug therapies are sufficiently different from earlier therapies to warrant reviewing the risk of TLS development. In this review, we will reassess the cancer-specific TLS risk based on new drug therapies and provide an overview of prevention and treatment methods.

Preventing and monitoring for tumor lysis syndrome and other toxicities of venetoclax during treatment of chronic lymphocytic leukemia.

Recent developments in the management of chronic lymphocytic leukemia (CLL) have moved the standard of care away from chemoimmunotherapy to targeted agents such as oral kinase inhibitors or BCL-2 antagonists, alone or in combination with anti-CD20 antibodies. Two different treatment approaches have evolved: continuous, indefinite treatment and, more recently, fixed-duration combination treatment. With venetoclax-based treatment, there is a requirement to follow the established guidelines for close monitoring during initiation and ramp up, to reduce the risk of tumor lysis syndrome. The patient's risk should be assessed before the initiation of venetoclax. Appropriate management strategies should be used, including uricosuric agents, hydration, and routine laboratory monitoring, per guidelines. With early identification, immediate management, and dose adjustments, we suggest that tumor lysis syndrome and other toxicities, such as neutropenia and infections, with venetoclax-based treatment can be dealt with successfully.

Prevention, recognition, and management of adverse events associated with gemtuzumab ozogamicin use in acute myeloid leukemia.

Gemtuzumab ozogamicin (GO), a humanized anti-CD33 monoclonal antibody conjugated to the cytotoxic antibiotic agent calicheamicin, is approved for the treatment of newly-diagnosed CD33 + AML in adults and children ≥ 1 month old, and relapsed or refractory CD33 + AML in adults and children ≥ 2 years old. GO treatment has been associated with an increased risk of hepatotoxicity and hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), especially following hematopoietic stem cell transplantation. Other non-specific serious adverse events (SAEs) associated with GO treatment are myelosuppression, bleeding/thrombocytopenia, infusion-related reaction, and tumor lysis syndrome. This report summarizes an expert panel of physicians' recommendations for the evaluation and management of SAEs following GO, emphasizing the prevention and management of VOD/SOS.

Evaluation of the safety and efficacy of low-dose rasburicase in critically ill children with haematological malignancies.

Background The recommended dose of rasburicase is quite expensive, thus limiting its use. Whether a lower dose of rasburicase would be equally effective for critically ill children, who often have more complicated situations and a higher risk of hospital death, is still unknown. Objective To explore the safety and efficacy of low-dose rasburicase in critically ill children with haematological malignancies who are at high risk of tumour lysis syndrome. Setting A single-centre retrospective cohort study. Method Children with haematological malignancies who had a history of rasburicase exposure during an intensive care unit stay were enrolled. Patients were divided into two groups according to the initial dosage of rasburicase: the standard-dose group (> 0.1 mg/kg/day) and the low-dose group (≤ 0.1 mg/kg/day). The adverse events and short-term prognosis of the two groups were compared. Results Thirty-seven children were selected, 22 in the standard-dose group and 15 in the low-dose group. The most common tumour type was Burkitt's lymphoma (81%), followed by acute lymphoblastic leukaemia (11%). All patients were at high risk of tumour lysis syndrome, and 73% of them had 3 or more tumour lysis syndrome risk factors. The uric acid levels of 90% of patients with hyperuricaemia returned to the normal range within 12 h (100% in the standard-dose group and 75% in the low-dose group, P = 0.083). Eighty-four percent of patients presented serious complications, including tumour lysis syndrome (73%), acute kidney injury (59%), renal replacement treatment (24%), respiratory failure (24%), disseminated intravascular coagulation (16%) and heart failure (11%). There was no significant difference in the incidence of serious complications between the two groups. The overall 7-day and 28-day survival rates after intensive care unit admission were 86% and 84%, respectively. The average length of stay in the intensive care unit was 9.92 ± 5.13 days. Neither the short-term mortality nor the length of stay in the intensive care unit were significantly different between the two groups. Conclusion Low-dose rasburicase is effective and may be an acceptable choice for critically ill children with haematological malignancies.

Prevention and Treatment of Tumor Lysis Syndrome in the Era of Onco-Nephrology Progress.

BACKGROUND: Tumor lysis syndrome (TLS) is an oncologic emergency due to a rapid break down of malignant cells usually induced by cytotoxic therapy, with hyperuricemia, hyperkalemia, hyperphosphatemia, hypocalcemia, and serious clinical consequences such as acute renal injury, cardiac arrhythmia, hypotension, and death. Rapidly expanding knowledge of cancer immune evasion mechanisms and host-tumor interactions has significantly changed our therapeutic strategies in hemato-oncology what resulted in the expanding spectrum of neoplasms with a risk of TLS. SUMMARY: Since clinical TLS is a life-threatening condition, identifying patients with risk factors for TLS development and implementation of adequate preventive measures remains the most critical component of its medical management. In general, these consist of vigilant laboratory and clinical monitoring, vigorous IV hydration, urate-lowering therapy, avoidance of exogenous potassium, use of phosphate binders, and - in high-risk cases - considering cytoreduction before the start of the aggressive agent or a gradual escalation of its dose. Key Messages: In patients with a high risk of TLS, cytotoxic chemotherapy should be given in the facility with ready access to dialysis and a treatment plan discussed with the nephrology team. In the case of hyperkalemia, severe hyperphosphatemia or acidosis, and fluid overload unresponsive to diuretic therapy, the early renal replacement therapy (RRT) should be considered. One must remember that in TLS, the threshold for RRT initiation may be lower than in other clinical situations since the process of cell breakdown is ongoing, and rapid increases in serum electrolytes cannot be predicted.

Leukocytapheresis for patients with acute myeloid leukemia presenting with hyperleukocytosis and leukostasis: a contemporary appraisal of outcomes and benefits.

Introduction: Hyperleukocytosis, defined as a total white blood cell count (WBC) >50 or more commonly >100 × 109 cells/L, is a presenting feature of acute myeloid leukemia (AML) in about 6-20% of cases and is associated with a higher risk of tumor lysis syndrome (TLS), disseminated intravascular coagulation (DIC), clinical leukostasis with end organ damage, and mortality.Areas covered: In this review, authors discuss the implications of hyperleukocytosis in AML and the current understanding of cytoreductive strategies with a focus on the use of leukocytapheresis.Expert commentary: Efforts to rapidly reduce peripheral myeloblasts have included the use of leukocytapheresis. Early studies demonstrated feasibility in reducing peripheral WBC and blast counts as well as clinically relevant patient outcomes which prompted its common use for many years. However, more recent data have directly challenged the previously touted reports of reduced TLS and DIC incidence as well as survival benefit, even in patients with clinical leukostasis. The use of leukocytapheresis remains highly controversial with wide practice variations among physicians, institutions, and countries given the lack of high-quality data, risks associated with leukocytapheresis itself, associated high costs, resource utilization, and lack of evidence-based clinical guidelines.

Recomendaciones para el manejo de la lisis tumoral / Recommendations for tumor lysis syndrome management

El síndrome de lisis tumoral representa una complicación potencialmente letal provocada por la liberación masiva de ácidos nucleicos, potasio y fosfato hacia la circulación como resultado de la lisis de células neoplásicas, las cuales se caracterizan por una rápida capacidad de proliferación y alta sensibilidad a fármacos. Esto puede ocurrir de forma espontánea antes del inicio del tratamiento y agravarse luego de haberse iniciado la quimioterapia. Presenta una alta mortalidad. Su prevención continúa siendo la medida terapéutica más importante. El cuadro clínico se caracteriza por la existencia de trastornos del metabolismo hidroelectrolítico, en particular, hipercalemia, hiperfosfatemia e hiperuricemia y por la aparición de una lesión renal aguda. Una adecuada intervención terapéutica implica hidratación intravenosa y medidas para prevenir o corregir las alteraciones metabólicas. En este artículo, se proponen lineamientos para seguir tanto en la etapa diagnóstica como en el tratamiento de esta complicación.

The tumor lysis syndrome represents a potentially lethal complication caused by the massive release of nucleic acids, potassium and phosphate into the circulation as a result of the lysis of neoplastic cells, which are characterized by a rapid proliferation capacity and high sensitivity to drugs. This may occur spontaneously prior to the start of treatment, becoming worse after the initiation of chemotherapy. It presents a high mortality; its prevention continues being the most important therapeutic measure. The clinical picture is characterized by the existence of hydroelectrolytic metabolism disorders, in particular hyperkalemia, hyperphosphatemia and hyperuricemia and by the appearance of an acute renal lesion. Adequate therapeutic intervention involves intravenous hydration and measures to prevent or correct metabolic alterations. This article proposes guidelines to follow both in the diagnostic stage and in the treatment of this complication.

Tumour lysis syndrome in patients with chronic lymphocytic leukaemia treated with BCL-2 inhibitors: risk factors, prophylaxis, and treatment recommendations.

Tumour lysis syndrome is a complication of chemotherapy for haematological malignancies; in particular, aggressive leukaemias and lymphomas. For haematological malignancies, targeted therapies, such as small molecule inhibitors and monoclonal antibodies, have a high anti-tumour activity, are well tolerated, and have a low incidence of associated tumour lysis syndrome. The BCL-2 inhibitor venetoclax has a high anti-tumour activity in chronic lymphocytic leukaemia, achieving deep remissions by potently inducing apoptosis and increasing the risk for tumour lysis syndrome. In this Viewpoint, we discuss the pathophysiology, risk factors, monitoring, changes in laboratory parameters, and clinical manifestations of tumour lysis syndrome, and the prophylaxis and treatments available for this complication. Prophylaxis and treatment strategies have been implemented as standard of care in patients receiving venetoclax to minimise the risk of both laboratory and clinical manifestations of tumour lysis syndrome.

Impact of early rasburicase on incidence of clinical tumor lysis syndrome in lymphoma.

Early administration of rasburicase to enhance uric acid (UA) elimination has been adopted without robust evidence in support of its impact on clinical outcomes in tumor lysis syndrome (TLS), specifically, the prevention of acute kidney injury (AKI). This was a retrospective cohort study of adult lymphoma patients at intermediate or high risk for TLS. Excluded patients had AKI or were on dialysis at hospital admission. The incidence of new AKI in the setting of TLS was described along with predictors of its development, including early rasburicase use. In 383 included patients, the incidence of new-onset AKI during hospitalization was 6%. Predictors included age, history of renal or cardiovascular disease, and UA >8 mg/dL. Rasburicase use did not significantly impact the risk of developing AKI (HR 2.3; p = .11). The UA level at the time of administration did not modify the effect of rasburicase on prevention of AKI (p = .36 for the interaction term).

Febuxostat administration for the prevention of tumour lysis syndrome: A meta-analysis.

WHAT IS KNOWN AND OBJECTIVE: Tumour lysis syndrome is an oncological emergency, characterized by rapid cytolysis leading to an abrupt rise of serum uric acid levels. The aim of the present meta-analysis is to evaluate the efficacy and safety of febuxostat as a preventive measure in patients at risk of tumour lysis syndrome development, by comparing it with allopurinol administration. METHODS: MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, Clinicaltrials.gov and Google Scholar databases were searched from inception to 15 December 2018. All studies evaluating the effectiveness of febuxostat in preventing tumour lysis syndrome were held eligible. RESULTS AND DISCUSSION: Six studies were included with a total of 658 patients. Compared to allopurinol, febuxostat achieved a similar response rate (OR: 1.39, 95% CI: [0.55, 3.51]) and tumour lysis syndrome incidence (OR: 1.01, 95% CI: [0.56, 1.81]). Serum uric acid levels did not differ between the investigated groups at the second (MD: -0.21 mg/dL, 95% CI: [-1.30, 0.88]) and seventh (MD: -0.43 mg/dL, 95% CI: [-1.38, 0.51]) day of treatment. Elevation of liver function tests was the most common adverse effect, although its incidence was similar among patients treated with allopurinol and febuxostat. WHAT IS NEW AND CONCLUSIONS: The present meta-analysis suggests that febuxostat may serve as an effective alternative to allopurinol in the prevention of tumour lysis syndrome. Future large-scale studies should define the optimal febuxostat dosage, explore the most appropriate population for its administration and better define its safety profile.

Cost-effectiveness analysis of rasburicase over standard of care for the prevention and treatment of tumor lysis syndrome in children with hematologic malignancies in China.

Aims: To conduct a lifetime cost-effectiveness analysis (CEA) of rasburicase compared with standard of care (SOC) for tumor lysis syndrome (TLS) in children with hematologic malignancies from the Chinese healthcare system perspective. Materials and methods: The CEA was performed using a decision tree model with a lifetime horizon. The model explores the cost-effectiveness of rasburicase vs SOC for both preventing TLS and treating established TLS among pediatric patients with acute myeloid leukemia (AML), acute lymphoid leukemia (ALL), and non-Hodgkin's lymphoma (NHL). Both the prophylaxis-use model and treatment-use model incorporate long-term health states of the diseases: survival without TLS and death. The efficacy data of rasburicase and SOC were obtained from published literature. Drug costs, healthcare resource utilization (HRU), and adverse event (AE) management costs were obtained via a published study with clinical experts. Costs in US dollar and quality-adjusted life year (QALY) are reported, and incremental cost-effectiveness ratios (ICERs) were also calculated. Uncertainties due to parameter fluctuations in the model were assessed through one-way sensitivity analysis and probabilistic sensitivity analysis (PSA). Results: During TLS prevention, compared with SOC, the ICER of rasburicase treatment in China are $17,580.04/QALY, $5,783.45/QALY, and $5,391.00/QALY for pediatric patients with AML, ALL, and NHL, respectively. For the established TLS treatment, compared with SOC, the ICERs of rasburicase treatment are $2,031.18/QALY, $1,142.93/QALY, and $990.37/QALY for pediatric patients with AML, ALL, and NHL, respectively. Limitations: The clinical data for SOC are based on the published study in China, and the rasburicase prevention or treatment failure rate was either calculated based on the risk ratio or directly from the clinical study among non-Chinese pediatric patients. Another study limitation was the lack of utility data for pediatric patients with TLS and without TLS. Thus, the utility scores of pediatric cancer survivors were used as an alternative. Conclusion: Rasburicase is estimated to be a cost-effective alternative to SOC in the prevention and treatment of TLS among Chinese pediatric patients with AML, ALL, and NHL.

Tumor Lysis, Adverse Events, and Dose Adjustments in 297 Venetoclax-Treated CLL Patients in Routine Clinical Practice.

PURPOSE: Clinical trials of venetoclax reported negligible rates of clinical tumor lysis syndrome (TLS) in patients with chronic lymphocytic leukemia (CLL) when using an extended dose escalation schedule. We aimed to understand TLS prophylaxis, rates of select adverse events (AE), and impact of dosing modifications in routine clinical practice. EXPERIMENTAL DESIGN: This retrospective cohort study included 297 CLL venetoclax-treated patients outside of clinical trials in academic and community centers. Demographics, baseline disease characteristics, venetoclax dosing, TLS risk and prophylaxis, and AEs were collected. RESULTS: The group was 69% male, 96% had relapsed/refractory CLL, 45% had deletion chromosome 17p, 84% had unmutated IGHV, 80% received venetoclax monotherapy, and median age was 67. TLS risk was categorized as low (40%), intermediate (32%), or high (28%), and 62% had imaging prior to venetoclax initiation. Clinical TLS occurred in 2.7% of patients and laboratory TLS occurred in 5.7%. Pre-venetoclax TLS risk group and creatinine clearance independently predict TLS development in multivariable analysis. Grade 3/4 AEs included neutropenia (39.6%), thrombocytopenia (29.2%), infection (25%), neutropenic fever (7.9%), and diarrhea (6.9%). Twenty-two patients (7.4%) discontinued venetoclax due to an AE. Progression-free survival was similar regardless of number of dose interruptions, length of dose interruption, and stable venetoclax dose. CONCLUSIONS: These data provide insights into current use of venetoclax in clinical practice, including TLS rates observed in clinical practice. We identified opportunities for improved adherence to TLS risk stratification and prophylaxis, which may improve safety.