Therapeutic Leukocytapheresis to relieve priapism due to leukostasis in CML patients: Our experience in a tertiary care centre

Hyperleukocytosis in leukemic patients may cause tumour lysis syndrome, disseminated intravascular coagulopathy, and leukostasis, resulting in decreased tissue perfusion and increasing the risk of mortality. Since the myeloid blasts are larger than lymphoid blasts and are less deformable, complications of leukostasis are seen more frequently in myeloid leukemia. Priapism is a less common complication associated with leukostasis in leukaemia patients that should be treated as soon as possible to avoid ischemic injuries. Although chemotherapeutic drugs such as hydroxyurea and imatinib are used to treat hyperleukocytosis in CML patients, leukocytapheresis (LCP) can achieve rapid cytoreduction. Prophylactic LCP could not offer any advantage over aggressive chemotherapy, but therapeutic leukocyte depletion has a proven role in patients having symptomatic leukostasis due to high tumour burden. Three patients with ischaemic priapism were reported at our institute's emergency department, where detumescence could not be achieved by distal shunting or aspiration with phenylephrine instillation. The procedure of therapeutic LCP was performed in all three patients on an emergency basis, which resolved painful priapism by rapid cytoreduction.

What Is Different in Acute Hematologic Malignancy-Associated ARDS? An Overview of the Literature

Background and Objectives: Acute hematologic malignancies are a group of heterogeneous blood diseases with a high mortality rate, mostly due to acute respiratory failure (ARF). Acute respiratory distress syndrome (ARDS) is one form of ARF which represents a challenging clinical condition. The paper aims to review current knowledge regarding the variable pathogenic mechanisms, as well as therapeutic options for ARDS in acute hematologic malignancy patients. Data collection: We provide an overview of ARDS in patients with acute hematologic malignancy, from an etiologic perspective. We searched databases such as PubMed or Google Scholar, including articles published until June 2022, using the following keywords: ARDS in hematologic malignancy, pneumonia in hematologic malignancy, drug-induced ARDS, leukostasis, pulmonary leukemic infiltration, pulmonary lysis syndrome, engraftment syndrome, diffuse alveolar hemorrhage, TRALI in hematologic malignancy, hematopoietic stem cell transplant ARDS, radiation pneumonitis. We included relevant research articles, case reports, and reviews published in the last 18 years. Results: The main causes of ARDS in acute hematologic malignancy are: pneumonia-associated ARDS, leukostasis, leukemic infiltration of the lung, pulmonary lysis syndrome, drug-induced ARDS, radiotherapy-induced ARDS, diffuse alveolar hemorrhage, peri-engraftment respiratory distress syndrome, hematopoietic stem cell transplantation-related ARDS, transfusion-related acute lung injury. Conclusions: The short-term prognosis of ARDS in acute hematologic malignancy relies on prompt diagnosis and treatment. Due to its etiological heterogeneity, precision-based strategies should be used to improve overall survival. Future studies should focus on identifying the relevance of such etiologic-based diagnostic strategies in ARDS secondary to acute hematologic malignancy.

Deletion of Tgfβ signal in activated microglia prolongs hypoxia-induced retinal neovascularization enhancing Igf1 expression and retinal leukostasis

Retinal neovascularization (NV) is the major cause of severe visual impairment in patients with ischemic eye diseases. While it is known that retinal microglia contribute to both physiological and pathological angiogenesis, the molecular mechanisms by which these glia regulate pathological NV have not been fully elucidated. In this study, we utilized a retinal microglia-specific Transforming Growth Factor-β (Tgfβ) receptor knock out mouse model and human iPSC-derived microglia to examine the role of Tgfβ signaling in activated microglia during retinal NV. Using a tamoxifen-inducible, microglia-specific Tgfβ receptor type 2 (Tgfβr2) knockout mouse [Tgfβr2 KO (ΔMG)] we show that Tgfβ signaling in microglia actively represses leukostasis in retinal vessels. Furthermore, we show that Tgfβ signaling represses expression of the pro-angiogenic factor, Insulin-like growth factor 1 (Igf1), independent of Vegf regulation. Using the mouse model of oxygen-induced retinopathy (OIR) we show that Tgfβ signaling in activated microglia plays a role in hypoxia-induced NV where a loss in Tgfβ signaling microglia exacerbates and prolongs retinal NV in OIR. Using human iPSC-derived microglia cells in an in vitro assay, we validate the role of Transforming Growth Factor-β1 (Tgfβ1) in regulating Igf1 expression in hypoxic conditions. Finally, we show that Tgfβ signaling in microglia is essential for microglial homeostasis and that the disruption of Tgfβ signaling in microglia exacerbates retinal NV in OIR by promoting leukostasis and Igf1 expression.

Hyperleukocytosis and Leukostasis in Acute Myeloid Leukemia: Can a Better Understanding of the Underlying Molecular Pathophysiology Lead to Novel Treatments?

Up to 18% of patients with acute myeloid leukemia (AML) present with a white blood cell (WBC) count of greater than 100,000/µL, a condition that is frequently referred to as hyperleukocytosis. Hyperleukocytosis has been associated with an adverse prognosis and a higher incidence of life-threatening complications such as leukostasis, disseminated intravascular coagulation (DIC), and tumor lysis syndrome (TLS). The molecular processes underlying hyperleukocytosis have not been fully elucidated yet. However, the interactions between leukemic blasts and endothelial cells leading to leukostasis and DIC as well as the processes in the bone marrow microenvironment leading to the massive entry of leukemic blasts into the peripheral blood are becoming increasingly understood. Leukemic blasts interact with endothelial cells via cell adhesion molecules such as various members of the selectin family which are upregulated via inflammatory cytokines released by leukemic blasts. Besides their role in the development of leukostasis, cell adhesion molecules have also been implicated in leukemic stem cell survival and chemotherapy resistance and can be therapeutically targeted with specific inhibitors such as plerixafor or GMI-1271 (uproleselan). However, in the absence of approved targeted therapies supportive treatment with the uric acid lowering agents allopurinol and rasburicase as well as aggressive intravenous fluid hydration for the treatment and prophylaxis of TLS, transfusion of blood products for the management of DIC, and cytoreduction with intensive chemotherapy, leukapheresis, or hydroxyurea remain the mainstay of therapy for AML patients with hyperleukocytosis.

Rapid Fire: Acute Blast Crisis/Hyperviscosity Syndrome

Emergency providers are likely to encounter patients with acute and chronic leukemias. In some cases, the first presentation to the emergency department may be for symptoms related to blast crisis and leukostasis. Making a timely diagnosis and consulting a hematologist can be life saving. Presenting symptoms are caused by complications of bone marrow infiltration and hyperleukocytosis with white blood cell counts over 100,000. Presentations may include fatigue (anemia), bleeding (thrombocytopenia), shortness of breath, and/or neurologic symptoms owing to hyperleukocytosis and subsequent leukostasis. Treatment of symptomatic cases involves induction chemotherapy and/or leukapheresis. Asymptomatic hyperleukocytosis can be treated with hydroxyurea.

[Successful induction therapy for acute myeloid leukemia complicated with brain hemorrhage and hyperleukocytosis]

Adequate management of hyperleukocytosis in patients with acute myeloid leukemia (AML) is essential for the prevention of life-threatening complications related to leukostasis and tumor lysis syndrome, but the optimal therapeutic strategy remains unclear. We report a 15-year-old girl with newly diagnosed AML who had extreme hyperleukocytosis (leukocyte count at diagnosis, 733,000/μl) leading to a brain hemorrhage. She was initially treated with hydroxyurea, but presented with brain hemorrhage due to leukostasis and underwent leukapheresis emergently with intensive care and mechanical ventilation. Full-dose standard induction chemotherapy was initiated after achieving gradual cytoreduction (leukocyte count, 465,000/μl) within five days after the initiation of therapy with hydroxyurea and leukapheresis. These treatments were successful and she experienced no complications. The patient ultimately recovered fully and was discharged with complete remission of AML. Although the effects of hydroxyurea and leukapheresis in the setting of hyperleukocytosis are still controversial, these initial treatments may contribute to successful bridging therapy followed by subsequent induction chemotherapy, especially in AML cases with extreme hyperleukocytosis or life-threatening leukostasis.

[Chronic myeloid leukemia complicated with cerebellar hemorrhage and acute hydrocephalus successfully treated with imatinib and intensive supportive care]

We report a case of a 46-year-old female demonstrating general fatigue and visual disturbances with retinal bleeding. She had a white blood cell count of 419,300/mm. Thereafter, she developed vomiting associated with vertigo caused by cerebellar hemorrhage, deteriorating to acute hydrocephalus secondary to obstruction of the cerebral aqueduct. Emergency procedures for cerebral protection, such as hyperventilation, administration of mannitol, and barbiturate coma, were performed. Bone marrow examination showed a positive BCR-ABL/t(9;22)(q34;q11) chromosomal translocation detected by FISH and RT-PCR (masked Ph) and she was diagnosed as having chronic myeloid leukemia (CML) in the chronic phase (CP). She was administered Ara-C, together with imatinib 600 mg/d through a nasogastric tube. Eight days later, she underwent successful extubation and recovered without any neurological defect. She was maintained on imatinib 400 mg/d and demonstrated a major molecular response at 15 months. Physicians need to be aware that brain hemorrhage may develop as an initial symptom of CML patients in CP.

Central nervous system complications of blastic hyperleukocytosis in childhood acute lymphoblastic leukemia: diagnostic and prognostic implications

Intracranial hemorrhage during blastic crisis is a rare but critically important occurrence in children with acute lymphoblastic leukemia. This form of hemorrhage has not been described since the advent of magnetic resonance imaging (MRI), leaving radiologists and clinicians unfamiliar with its unique imaging features. The authors describe 2 boys with severe intracranial pathology secondary to blastic hyperleukocytosis. Both patients were followed with serial MRI. Imaging findings in relation to the pathophysiology of white matter leukostasis are discussed and implications for treatment and prognosis are considered.

Analyzing cell mechanics in hematologic diseases with microfluidic biophysical flow cytometry

Pathological processes in hematologic diseases originate at the single-cell level, often making measurements on individual cells more clinically relevant than population averages from bulk analysis. For this reason, flow cytometry has been an effective tool for single-cell analysis of properties using light scattering and fluorescence labeling. However, conventional flow cytometry cannot measure cell mechanical properties, alterations of which contribute to the pathophysiology of hematologic diseases such as sepsis, diabetic retinopathy, and sickle cell anemia. Here we present a high-throughput microfluidics-based 'biophysical' flow cytometry technique that measures single-cell transit times of blood cell populations passing through in vitro capillary networks. To demonstrate clinical relevance, we use this technique to characterize biophysical changes in two model disease states in which mechanical properties of cells are thought to lead to microvascular obstruction: (i) sepsis, a process in which inflammatory mediators in the bloodstream activate neutrophils and (ii) leukostasis, an often fatal and poorly understood complication of acute leukemia. Using patient samples, we show that cell transit time through and occlusion of microfluidic channels is increased for both disease states compared to control samples, and we find that mechanical heterogeneity of blood cell populations is a better predictor of microvascular obstruction than average properties. Inflammatory mediators involved in sepsis were observed to significantly affect the shape and magnitude of the neutrophil transit time population distribution. Altered properties of leukemia cell subpopulations, rather than of the population as a whole, were found to correlate with symptoms of leukostasis in patients-a new result that may be useful for guiding leukemia therapy. By treating cells with drugs that affect the cytoskeleton, we also demonstrate that their transit times could be significantly reduced. Biophysical flow cytometry offers a low-cost and high-throughput diagnostic and drug discovery platform for hematologic diseases that affect microcirculatory flow.

Long-term global retinal microvascular changes in a transgenic vascular endothelial growth factor mouse model

AIMS/HYPOTHESIS

Vascular endothelial growth factor (VEGF) plays a pivotal role in the pathogenesis of diabetic retinopathy. We investigated whether transgenic mice with moderate VEGF expression in photoreceptors (trVEGF029) developed changes similar to diabetic retinopathy and whether retinopathy progressed with time.

MATERIALS AND METHODS

Human VEGF(165) (hVEGF(165)) expression was analysed using ELISA and quantitative RT-PCR; serum glucose levels were also measured. Fundus fluorescein angiography (FA) was used to screen the degree of retinopathy from 6 weeks. Dynamic changes in the density of retinal microvasculature, as well as other changes similar to diabetic retinopathy, including retinal leucostasis, capillary endothelial cell and pericyte loss, and numbers of acellular capillaries, were quantified.

RESULTS

trVEGF029 mice were normoglycaemic and showed a moderate, short-term hVEGF(165) upregulation for up to 3 weeks. Changes in the retinal microvasculature not only mimicked those seen in diabetic retinopathy, but also showed similar pathological progression with time. FA at 6 weeks identified two phenotypes, mild and moderate, which were distinguished by the extent of vascular leakage. Quantitative analysis of diabetic retinopathy-like changes revealed that these parameters were tightly correlated with the initial degree of vascular leakage; low levels reflected slow and limited retinal microvascular changes in mild cases and high levels reflected more rapid and extensive changes in moderate cases.

CONCLUSIONS/INTERPRETATION

The data suggest that even an early short-term elevation in hVEGF(165) expression might set a train of events that lead to progressive retinopathy. Induction of many features characteristic of diabetic retinopathy in trVEGF029 enables mechanisms leading to the disease state to be examined, and provides a relevant animal model for testing novel therapeutics.

Correlation between expression of CD56/NCAM and severe leukostasis in hyperleukocytic acute myelomonocytic leukaemia

OBJECTIVE

The possible contribution of surface molecules to the development of leukostasis syndrome in hyperleukocytic acute myeloid leukaemia (AML) was assessed by routine immunophenotyping and grading of the probability of clinical leukostasis.

METHODS

Fifty-three patients (23 women, 30 men, median age 59 yr) with hyperleukocytic AML [white blood count (WBC) above 50 x 10(9)/L] were graded for the probability of clinical leukostasis according to the severity of neurologic, pulmonary and other symptoms possibly caused by leukostasis using a recently published scoring system. Age, WBC, absolute blast count, haemoglobin, cytogenetic risk group, infection, relative CD56 expression and absolute count of CD56 positive blasts were analyzed in multivariate stepwise backward logistic regression analysis.

RESULTS

In patients with acute monocytic leukaemia (AML M4/M5) the absolute count of leukaemic blasts expressing CD56/NCAM was highly associated with the development of symptoms graded as highly probable leukostasis and all three patients succumbing to early death were CD56 positive. Only the absolute count of CD56 positive blasts was a significant predictor of risk of severe leukostasis (P = 0.020). This was not found in AML without monocytic involvement (AML M1, M2, M3v).

CONCLUSIONS

The expression of CD56/NCAM, a surface marker used in routine immunophenotyping of AML, may help to predict severe and potentially fatal leukostasis in hyperleukocytic acute myelomonocytic leukaemia. These results emphasize the usefulness of this four-stage clinical grading scale for analysing the factors, which lead to severe leukostasis in hyperleukocytic patients. We extend previous findings that the mechanisms of leukostasis are different depending on the involvement of the monocytic lineage.

Therapeutic leukapheresis in hyperleukocytic leukaemias--the experience of a tertiary institution in Singapore

INTRODUCTION

Hyperleukocytic leukaemias are associated with early mortality due to respiratory or neurological complications. They result from endothelial damage secondary to leukostasis. Leukapheresis, which aims to lower the white blood cell (WBC) count, has been used in certain patients to reduce the threat from leukostasis. However, there are very few published clinical investigations on the most appropriate use of leukapheresis in hyperleukocytosis.

MATERIALS AND METHODS

We performed a retrospective analysis of 14 patients with hyperleukocytic leukaemia who presented to our institution and underwent therapeutic leukapheresis. We compare their clinical and biological characteristics and investigate the impact of leukapheresis on early mortality and long-term prognosis.

RESULTS

The median presenting WBC count was 439 x 10(3)/mm(3). Although patients with acute myeloid leukaemia (AML) had the lowest median presenting WBC counts, they constituted the largest group of patients with symptomatic hyperleukocytosis. Leukapheresis was highly effective, with the mean absolute and percentage reduction in WBC after each cycle being 126 x 10(3)/mm(3) and 31.9% respectively. Four patients with AML died within 2 weeks of presentation despite prompt and effective leukapheresis.

CONCLUSION

The interaction between the leukaemic cells and the vascular environment, a mechanism that none of the current therapies directly address, is probably more important in causing leukostasis than the absolute cell count itself.

Aseptic necrosis of both femoral heads as first symptom of chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a disease of the elderly; in rare cases it occurs in childhood or adolescence. One complication at primary diagnosis is leukostasis, which usually causes respiratory, retinal, or central nervous symptoms. In this report we describe the case of a 24-year-old woman who developed aseptic necrosis of both femoral heads, which was successfully treated by bore holes in the femoral heads. This is a very rare complication of severe leukostasis, leading to the diagnosis of CML in this case. To our knowledge, this is the first case of an adult patient showing aseptic necrosis of femoral heads caused by leukostasis.

Pulmonary leukostasis mimicking pulmonary embolism

We report a case of a 32-year-old woman who presented with shortness of breath and pleuritic chest pain, and mismatched perfusion defects on a ventilation-perfusion scan suspicious for pulmonary embolism. However, subsequent data revealed the diagnosis of acute myelogenous leukemia with hyperleukocytosis and associated pulmonary leukostasis. Unfortunately, the patient died despite urgent leukopheresis. Autopsy examination revealed extensive infiltration of leukemic cells in all major organs with no evidence of pulmonary embolism. This case highlights the clinical, radiographic and histologic features of pulmonary leukostasis, and reminds the clinician that not all ventilation-perfusion mismatching is due to thromboembolic disease.

Sudden death in a patient with chronic lymphocytic leukemia

The authors describe a 51-year-old man with chronic lymphocytic leukemia who presented with respiratory distress and then died suddenly while in hospital. Autopsy revealed pulmonary leukostasis and a large intracardiac mass containing mostly mature lymphocytes and fibrin. Although leukostasis and lymphocyte thrombi have been described (albeit rarely) in chronic lymphocytic leukemia, an intracardiac "clot" has not. It seems plausible that this intracardiac mass caused the patient's death.

Acute cardiorespiratory failure as presenting symptom of chronic lymphocytic leukemia

A patient with acute cardiorespiratory failure caused by hyperleukocytosis due to chronic lymphocytic leukaemia (CLL) is described. Although acute pulmonary failure due to leukostasis is a known and often postmortem finding in patients with acute myelocytic leukaemia (AML) or chronic myelocytic leukaemia (CML) in blastic crises, it is rare in CLL.