Insufficient secretion of pancreatic FGF21 is the toxicological mechanism and therapeutic target of asparaginase-associated pancreatitis.

Asparaginase-associated pancreatitis (AAP) is a severe and potentially life-threatening drug-induced pancreas targeted toxicity in the combined chemotherapy of acute lymphoblastic leukemia among children and adolescents. The toxicological mechanism of AAP is not yet clear, and there are no effective preventive and treatment measures available clinically. Fibroblast growth factor 21 (FGF21) is a secretory hormone that regulates lipid, glucose, and energy metabolism balance. Acinar tissue is the main source of pancreatic FGF21 protein and plays an important role in maintaining pancreatic metabolic balance. In this study, we found that the decrease of FGF21 in pancreas is closely related to AAP. Pegaspargase (1 IU/g) induces widespread edema and inflammatory infiltration in the pancreas of rats/mice. The specific expression of FGF21 in the acinar tissue of AAP rats was significantly downregulated. Asparaginase caused dysregulation of the ATF4/ATF3/FGF21 axis in acinar tissue or cells, and thus mediated the decrease of FGF21. It greatly activated ATF3 in the acinar, which competed with ATF4 for the Fgf21 promoter, thereby inhibiting the expression of FGF21. Pharmacological replacement of FGF21 (1 mg/kg) or PERK inhibitors (GSK2656157, 25 mg/kg) can significantly mitigate the pancreatic tissue damage and reduce markers of inflammation associated with AAP, representing potential strategies for the prevention and treatment of AAP.

Toxicity of a Modified PEG-Asparaginase-Based SMILE Regimen Is Comparable to L-Asparaginase-Based SMILE in a Non-Asian Population.

INTRODUCTION: L-asparaginase-based chemotherapy regimens are effective for treating chemotherapy-resistant natural killer- (NK-) cell neoplasms. To treat these lymphoma subtypes in Asia, where NK/T-cell lymphomas are more prevalent, the NK-Cell Tumor Study Group developed the SMILE regimen, which includes a steroid, methotrexate, ifosfamide, L-asparaginase, and etoposide. In the US however, the only commercially available form of asparaginase is the pegylated form (PEG-asparaginase) which has been incorporated into a modified SMILE (mSMILE). We sought to study the toxicity associated with replacing L-asparaginase with PEG-asparaginase in mSMILE. PATIENTS AND METHODS: We retrospectively identified all adult patients treated with the mSMILE chemotherapy regimen in our database at Moffitt Cancer Center (MCC) between December 1, 2009, and July 30, 2021. Patients were included if they were treated with mSMILE irrespective of their underlying diagnosis. Toxicity was assessed using Common Terminology Criteria for Adverse Events (CTCAE) version 5. The rate of toxicity in our mSMILE treatment group was numerically compared to data published in a metanalysis of the SMILE regimen's toxicity (Pokrovsky et al., 2019). RESULTS: A total of 21 patients were treated with mSMILE at MCC during the 12-year analysis window. Compared to patients receiving the L-asparaginase-based SMILE, patients receiving mSMILE experienced grade 3 or 4 leukopenia less often, with a toxicity rate of 62% (median with SMILE, 85% [95% CI, 74%-95%]); thrombocytopenia, however, was more common, with a toxicity rate of 57% (median with SMILE, 48% [95% CI, 40%-55%]). Other hematological, hepatic and coagulation related toxicities were also reported. CONCLUSION: In a non-Asian population, the mSMILE regimen with PEG-asparaginase is a safe alternative to the L-asparaginase-based SMILE regimen. There is a comparable risk of hematological toxicity, and no treatment-related mortality was seen in our population.

Allergic reactions to asparaginase: retrospective cohort study in pediatric patients with acute lymphoid leukemia

ABSTRACT Introduction: To assess the frequency of allergic reactions to asparaginase (ASP) and possible risk factors for reactions in a cohort of pediatric patients. Method: The study was performed based on retrospective data from patients under acute lymphoid leukemia treatment in a general university hospital located in southern Brazil. Information on patients who used ASP from 2010 to 2017 was collected. Allergic reactions were identified in electronic medical records. Results: Among the 98 patients included in the study, 16 (16.3 %) experienced an allergic reaction to native l-asparaginase (L-ASP). Of the 22 patients (22.4 %) that received only intravenous (IV) administration of l-ASP, 10 (62.5 %) had allergic reactions, while 48 patients (49 %) received intramuscular (IM) administration and 28 (28.6 %) received IV and IM administrations. The occurrence of allergic reactions differed between the groups (p < 0.001), and IV administration was associated with allergic reactions. Association was also observed between the severity of the reaction and the route of administration, with the IM route associated with grade 2 and IV route associated with grade 3. Occurrence of allergic reactions was higher when the commercial formulation of l-ASP, Leuginase®, was used (p = 0.0009 in the analysis per patient and p = 0.0003 in the analysis per administration). Conclusions: The IV administration and commercial Leuginase® presentation were associated with more allergic reactions in the study population, which corroborates the findings in the literature. The IV route was also associated with higher severity of reactions in the present study.

National Italian Delphi panel consensus: which measures are indicated to minimize pegylated-asparaginase associated toxicity during treatment of adult acute lymphoblastic leukemia?

BACKGROUND: L-asparaginase (L-ASP) is a key component of acute lymphoblastic leukemia (ALL) treatment, but its use in clinical practice raises challenges to clinicians due to a relatively high incidence of drug-related adverse events, mainly in adult patients. In the past years the use of ASP in adult population has been mainly limited due to a poor knowledge of its safety profile and to an approximate management of ASP-related toxicity. Recently the development of pediatric-inspired treatment protocols for adult ALL has led to a wider use of ASP and since 2010 in Italy three national treatment protocols including Pegylated asparaginase (Peg-ASP) have been sequentially developed for adolescents, young adults and adults with Philadelphia-negative (Ph-) ALL. METHODS: With the aim to better understand the approach adopted in Italian centers for the management and prevention of Peg-ASP toxicity in adult ALL and to provide practical, consensus-based recommendations, a board of 6 Italian clinicians, with known expertise in adult ALL, designed 41 consensus statements on current challenges on the management of Peg-ASP associated toxicity. A group of 19 clinical experts in the field then rated these statements using the 5-point Likert-type scale (1 = strongly disagree; 5 = strongly agree). RESULTS: The main Peg-ASP related issues identified by the board included: 1) clinician's attitudes; 2) toxicity profile; 3) hypersensitivity reactions; 4) hepatic toxicity; 5) hepatic and/or metabolic toxicity; 6) hemorrhagic/thrombotic toxicity; 7) pancreatitis; 8) metabolic toxicity management and prevention; 9) activity levels monitoring. Overall, participants agreed on most statements, except those addressing the potential contraindications to the treatment with Peg-ASP, such as patients with a diagnosis of chronic liver disease or the subsequent administrations of the drug in patients who had previously developed chemical pancreatitis or severe metabolic toxicity. Participants agreed that adult patients with ALL should receive Peg-Asp because this drug is essential to improve treatment results. CONCLUSIONS: The panel agreed that a critical evaluation of specific risk factors for each patient is crucial in order to reduce the risk of adverse events and specific advices in the management of Peg-ASP toxicities are reported.

Asparaginase-induced hepatotoxicity: rapid development of cholestasis and hepatic steatosis.

BACKGROUND: L-Asparaginase is a bacterial enzyme used in the treatment of acute lymphoblastic leukemia. In the ongoing U.S. Drug-Induced Liver Injury Network (DILIN) prospective study, standard and pegylated asparaginase were the most frequent cause of liver injury with jaundice among anti-cancer agents (8 of 40: 20%). The unique features of this hepatotoxicity are described. METHODS: Eight cases from 5 DILIN centers were reviewed for clinical course, laboratory values, imaging, and histopathology. RESULTS: Seven females, aged 29-59 years, and one 8-year-old boy, all with leukemia, developed jaundice within 9-21 days (median 15 days) of starting asparaginase or pegaspargase, during the first (n = 6) or second (n = 2) cycle. Prominent symptoms were jaundice (n = 8), fatigue (6), abdominal pain (6) but rarely pruritus (1). Initial median ALT level was 284 U/L (range 83-1076), Alk P 159 U/L (64-452), and bilirubin 4.4 mg/dL (3.7-8.4). Bilirubin levels rose thereafter in all patients to median peak of 17.5 mg/dL (11.7-25.7), INR rose to 1.1-1.7 and serum albumin fell to 1.5-2.6 g/dL. Hepatic imaging revealed fatty liver in all patients. Liver biopsy showed steatosis but minimal hepatocyte necrosis. One patient restarted on pegaspargase re-developed less severe injury. CONCLUSION: Asparaginase is a common cause of antineoplastic-induced liver injury with jaundice, typically with short latency, marked steatosis, and prolonged jaundice, which can lead to delays in antileukemic therapy. The cause of injury is likely direct inhibition of hepatic protein synthesis caused by asparagine depletion.

Galactose protects against cell damage in mouse models of acute pancreatitis.

Acute pancreatitis (AP), a human disease in which the pancreas digests itself, has substantial mortality with no specific therapy. The major causes of AP are alcohol abuse and gallstone complications, but it also occurs as an important side effect of the standard asparaginase-based therapy for childhood acute lymphoblastic leukemia. Previous investigations into the mechanisms underlying pancreatic acinar cell death induced by alcohol metabolites, bile acids, or asparaginase indicated that loss of intracellular ATP generation is an important factor. We now report that, in isolated mouse pancreatic acinar cells or cell clusters, removal of extracellular glucose had little effect on this ATP loss, suggesting that glucose metabolism was severely inhibited under these conditions. Surprisingly, we show that replacing glucose with galactose prevented or markedly reduced the loss of ATP and any subsequent necrosis. Addition of pyruvate had a similar protective effect. We also studied the effect of galactose in vivo in mouse models of AP induced either by a combination of fatty acids and ethanol or asparaginase. In both cases, galactose markedly reduced acinar necrosis and inflammation. Based on these data, we suggest that galactose feeding may be used to protect against AP.

L-asparaginase isolated from Streptomyces ansochromogenes promotes Th1 profile and activates CD8+ T cells in human PBMC: an in vitro investigation.

AIMS: A new L-asparaginase produced by Streptomyces ansochromogenes UFPEDA 3420 actinobacteria was used in this study against human lymphocyte cultures to evaluate the immunological profile induced by this enzyme. METHODS AND RESULTS: Cultures of lymphocytes were stimulated with S. ansochromogenes L-asparaginase, and cytotoxicity, cell viability, cell stimulation and cytokine production were analysed. This new S. ansochromogenes L-asparaginase induced activation and proliferation of the TCD8+ lymphocyte subset and produced higher TNF-α, IFN-γ, IL-2 and IL-10 levels in a 24-h assay. CONCLUSION: Streptomyces ansochromogenes L-asparaginase is a promising molecule to be used in in vivo models and to deepen preclinical tests against acute lymphoblast leukaemia. SIGNIFICANCE AND IMPACT OF STUDY: L-asparaginase is an indispensable component of the chemotherapeutic treatment of acute lymphoblast leukaemia (ALL) and acute myeloid leukaemia (AML). Currently, drugs such as Asparaginase® , Kidrolase® , and Elspar® and Erwinase® are efficient against leukemic disease, but promote immunosuppression and other side effects in human organisms. Our purified S. ansochromogenes L-asparaginase showed promissory results inducing, in vitro, higher immunostimulation in human PBMC, especially in T CD8+ lymphocyte subsets.

Pegylated-asparaginase during induction therapy for adult acute lymphoblastic leukaemia: toxicity data from the UKALL14 trial.

Safety and efficacy data on pegylated asparaginase (PEG-ASP) in adult acute lymphoblastic leukaemia (ALL) induction regimens are limited. The UK National Cancer Research Institute UKALL14 trial NCT01085617 prospectively evaluated the tolerability of 1000 IU/m2 PEG-ASP administered on days 4 and 18 as part of a five-drug induction regimen in adults aged 25-65 years with de novo ALL. Median age was 46.5 years. Sixteen of the 90 patients (median age 56 years) suffered treatment-related mortality during initial induction therapy. Eight of the 16 died of sepsis in combination with hepatotoxicity. Age and Philadelphia (Ph) status were independent variables predicting induction death >40 versus ⩽40 years, odds ratio (OR) 18.5 (2.02-169.0), P=0.01; Ph- versus Ph+ disease, OR 13.60 (3.52-52.36), P<0.001. Of the 74 patients who did not die, 37 (50.0%) experienced at least one grade 3/4 PEG-ASP-related adverse event, most commonly hepatotoxicity (36.5%, n=27). A single dose of PEG-ASP achieved trough therapeutic enzyme levels in 42/49 (86%) of the patients tested. Although PEG-ASP delivered prolonged asparaginase activity in adults, it was difficult to administer safely as part of the UKALL14 intensive multiagent regimen to those aged >40 years. It proved extremely toxic in patients with Ph+ ALL, possibly owing to interaction with imatinib.

Purification, characterization, cytotoxicity and anticancer activities of L-asparaginase, anti-colon cancer protein, from the newly isolated alkaliphilic Streptomyces fradiae NEAE-82.

L-asparaginase is an important enzyme as therapeutic agents used in combination with other drugs in the treatment of acute lymphoblastic leukemia. A newly isolated actinomycetes strain, Streptomyces sp. NEAE-82, was potentially producing extracellular L-asparaginase, it was identified as Streptomyces fradiae NEAE-82, sequencing product was deposited in the GenBank database under accession number KJ467538. L-asparaginase was purified from the crude enzyme using ammonium sulfate precipitation, dialysis and ion exchange chromatography using DEAE Sepharose CL-6B. Further the kinetic studies of purified enzyme were carried out. The optimum pH, temperature and incubation time for maximum L-asparaginase activity were found to be 8.5, 40 °C and 30 min, respectively. The optimum substrate concentration was found to be 0.06 M. The Km and Vmax of the enzyme were 0.01007 M and 95.08 Uml(-1)min(-1), respectively. The half-life time (T1/2) was 184.91 min at 50 °Ð¡, while being 179.53 min at 60 °Ð¡. The molecular weight of the subunits of L-asparaginase was found to be approximately 53 kDa by SDS-PAGE analysis. The purified L-asparaginase showed a final specific activity of 30.636 U/mg protein and was purified 3.338-fold. The present work for the first time reported more information in the production, purification and characterization of L-asparaginase produced by newly isolated actinomycetes Streptomyces fradiae NEAE-82.

Albumin/asparaginase capsules prepared by ultrasound to retain ammonia.

Asparaginase reduces the levels of asparagine in blood, which is an essential amino acid for the proliferation of lymphoblastic malign cells. Asparaginase converts asparagine into aspartic acid and ammonia. The accumulation of ammonia in the bloodstream leads to hyperammonemia, described as one of the most significant side effects of asparaginase therapy. Therefore, there is a need for asparaginase formulations with the potential to reduce hyperammonemia. We incorporated 2 % of therapeutic enzyme in albumin-based capsules. The presence of asparaginase in the interface of bovine serum albumin (BSA) capsules showed the ability to hydrolyze the asparagine and retain the forming ammonia at the surface of the capsules. The incorporation of Poloxamer 407 in the capsule formulation further increased the ratio aspartic acid/ammonia from 1.92 to 2.46 (and 1.10 from the free enzyme), decreasing the levels of free ammonia. This capacity to retain ammonia can be due to electrostatic interactions and retention of ammonia at the surface of the capsules. The developed BSA/asparaginase capsules did not cause significant cytotoxic effect on mouse leukemic macrophage cell line RAW 264.7. The new BSA/asparaginase capsules could potentially be used in the treatment of acute lymphoblastic leukemia preventing hyperammonemia associated with acute lymphoblastic leukemia (ALL) treatment with asparaginase.

General control nonderepressible 2 deletion predisposes to asparaginase-associated pancreatitis in mice.

Treatment with the antileukemic agent asparaginase can induce acute pancreatitis, but the pathophysiology remains obscure. In the liver of mice, eukaryotic initiation factor 2 (eIF2) kinase general control nonderepressible 2 (GCN2) is essential for mitigating metabolic stress caused by asparaginase. We determined the consequences of asparaginase treatment on the pancreata of wild-type (WT, GCN2-intact) and GCN2-deleted (ΔGcn2) mice. Mean pancreas weights in ΔGcn2 mice treated with asparaginase for 8 days were increased (P < 0.05) above all other groups. Histological examination revealed acinar cell swelling and altered staining of zymogen granules in ΔGcn2, but not WT, mice. Oil Red O staining and measurement of pancreas triglycerides excluded lipid accumulation as a contributor to acini appearance. Instead, transmission electron microscopy revealed dilatation of the endoplasmic reticulum (ER) and accumulation of autophagic vacuoles in the pancreas of ΔGcn2 mice treated with asparaginase. Consistent with the idea that loss of GCN2 in a pancreas exposed to asparaginase induced ER stress, phosphorylation of protein kinase R-like ER kinase (PERK) and its substrate eIF2 was increased in the pancreas of asparaginase-treated ΔGcn2 mice. In addition, mRNA expression of PERK target genes, activating transcription factors 4, 3, and 6 (Atf4, Atf3, and Atf6), fibroblast growth factor 21 (Fgf21), heat shock 70-kDa protein 5 (Hspa5), and spliced Xbp1 (sXbp1), as well as pancreas mass, was elevated in the pancreas of asparaginase-treated ΔGcn2 mice. Furthermore, genetic markers of oxidative stress [sirtuin (Sirt1)], inflammation [tumor necrosis factor-α (Tnfα)], and pancreatic injury [pancreatitis-associated protein (Pap)] were elevated in asparaginase-treated ΔGcn2, but not WT, mice. These data indicate that loss of GCN2 predisposes the exocrine pancreas to a maladaptive ER stress response and autophagy during asparaginase treatment and represent a genetic basis for development of asparaginase-associated pancreatitis.

Effect of premedications in a murine model of asparaginase hypersensitivity.

A murine model was developed that recapitulates key features of clinical hypersensitivity to Escherichia coli asparaginase. Sensitized mice developed high levels of anti-asparaginase IgG antibodies and had immediate hypersensitivity reactions to asparaginase upon challenge. Sensitized mice had complete inhibition of plasma asparaginase activity (P = 4.2 × 10(-13)) and elevated levels of mouse mast cell protease 1 (P = 6.1 × 10(-3)) compared with nonsensitized mice. We investigated the influence of pretreatment with triprolidine, cimetidine, the platelet activating factor (PAF) receptor antagonist CV-6209 [2-(2-acetyl-6-methoxy-3,9-dioxo-4,8-dioxa-2,10-diazaoctacos-1-yl)-1-ethyl-pyridinium chloride], or dexamethasone on the severity of asparaginase-induced allergies. Combining triprolidine and CV-6209 was best for mitigating asparaginase-induced hypersensitivity compared with nonpretreated, sensitized mice (P = 1.2 × 10(-5)). However, pretreatment with oral dexamethasone was the only agent capable of mitigating the severity of the hypersensitivity (P = 0.03) and partially restoring asparaginase activity (P = 8.3 × 10(-4)). To rescue asparaginase activity in sensitized mice without requiring dexamethasone, a 5-fold greater dose of asparaginase was needed to restore enzyme activity to a similar concentration as in nonsensitized mice. Our results suggest a role of histamine and PAF in asparaginase-induced allergies and indicate that mast cell-derived proteases released during asparaginase allergy may be a useful marker of clinical hypersensitivity.

Differential mechanisms of asparaginase resistance in B-type acute lymphoblastic leukemia and malignant natural killer cell lines.

Bacterial L-asparaginase (ASNase), hydrolyzing L-asparagine (Asn), is an important drug for treating patients with acute lymphoblastic leukaemia (ALL) and natural killer (NK) cell lymphoma. Although different native or pegylated ASNase-based chemotherapy are efficient, disease relapse is frequently observed, especially in adult patients. The neo-synthesis of Asn by asparagine synthetase (AsnS) following ASNase treatment, which involves the amino acid response and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathways, is believed to be the basis of ASNase-resistance mechanisms. However, AsnS expression has not emerged as an accurate predictive factor for ASNase susceptibility. The aim of this study was to identify possible ASNase sensitivity/resistance-related genes or pathways using a new asparaginase, namely a pegylated r-crisantaspase, with a focus on classic Asn-compensatory responses and cell death under conditions of Asn/L-glutamine limitation. We show that, for B-ALL cell lines, changes in the expression of apoptosis-regulatory genes (especially NFκB-related genes) are associated with ASNase susceptibility. The response of malignant NK cell lines to ASNase may depend on Asn-compensatory mechanisms and other cellular processes such as cleavage of BCL2A1, a prosurvival member of the Bcl-2 protein family. These results suggest that according to cellular context, factors other than AsnS can influence ASNase susceptibility.

The eukaryotic initiation factor 2 kinase GCN2 protects against hepatotoxicity during asparaginase treatment.

Asparaginase is an important drug in the treatment regimen for acute lymphoblastic leukemia. Asparaginase depletes circulating asparagine and glutamine, activating an amino acid stress response (AAR) involving phosphorylation of eukaryotic initiation factor 2 (eIF2) by general control nonderepressible kinase 2 (GCN2). We hypothesized that GCN2 functions to mitigate hepatic stress during asparaginase therapy by activating the AAR. To test this idea, C57BL/6J wild-type mice (Gcn2(+/+)) and those deleted for Gcn2 (Gcn2(-/-)) were injected with asparaginase or saline excipient one time daily for 1 or 6 days. In liver, increased phosphorylation of eIF2 and mRNA expression of AAR target genes activating transcription factor 4, asparagine synthetase, eIF4E-binding protein 1, and CAAT enhancer-binding protein homologous protein were significantly blunted or blocked in the liver of Gcn2(-/-) mice. Loss of AAR during asparaginase coincided with increases in mammalian target of rapamycin signaling, hepatic triglyceride accumulation, and DNA damage in association with genetic markers of oxidative stress (glutathione peroxidase) and inflammation (tumor necrosis factor alpha-α). Although asparaginase depleted circulating asparagine in both Gcn2(+/+) and Gcn2(-/-) mice, all other amino acids, including plasma glutamine, were elevated in the plasma of Gcn2(-/-) mice. This study shows that loss of GCN2 promotes oxidative stress and inflammatory-mediated DNA damage during asparaginase therapy, suggesting that patients with reduced or dysfunctional AAR may be at risk of developing hepatic complications during asparaginase treatment.

Postinduction dexamethasone and individualized dosing of Escherichia Coli L-asparaginase each improve outcome of children and adolescents with newly diagnosed acute lymphoblastic leukemia: results from a randomized study--Dana-Farber Cancer Institute ALL Consortium Protocol 00-01.

PURPOSE: We assessed the toxicity and efficacy of dexamethasone and a novel dosing method of Escherichia coli L-asparaginase (EC-Asnase) in children and adolescents with newly diagnosed acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Patients achieving complete remission (CR) on Dana-Farber Cancer Institute ALL Consortium Protocol 00-01 were eligible for random assignment to 1) dexamethasone or prednisone, administered as 5-day pulses, every 3 weeks, and 2) weekly EC-Asnase, administered as a 25,000 IU/m(2) fixed dose (FD) or individualized dose (ID) starting at 12,500-IU/m(2), adjusted every 3 weeks based on nadir serum asparaginase activity (NSAA) determinations. RESULTS: Between 2000 and 2004, 492 evaluable patients (ages 1 to 18 years) enrolled; 473 patients (96%) achieved CR. Four hundred eight patients (86%) participated in the corticosteroid randomization and 384 patients (81%) in the EC-Asnase randomization. With 4.9 years of median follow-up, dexamethasone was associated with superior 5-year event-free survival (EFS; 90% v 81% for prednisone; P = .01) but higher rates of infection (P = .03) and, in older children, higher cumulative incidence of osteonecrosis (P = .02) and fracture (P = .06). ID EC-Asnase had superior 5-year EFS (90% v 82% for FD; P = .04), but did not reduce the frequency of asparaginase-related toxicity. Multivariable analysis identified both dexamethasone and ID EC-Asnase as independent predictors of favorable EFS. CONCLUSION: There was no overall difference in skeletal toxicity by corticosteroid type; dexamethasone was associated with more infections and, in older children, increased incidence of osteonecrosis and fracture. There was no difference in asparaginase-related toxicity by EC-Asnase dosing method. Dexamethasone and ID EC-Asnase were each associated with superior EFS. Monitoring NSAA during treatment with EC-Asnase may be an effective strategy to improve outcome in pediatric ALL.

The eIF2 kinase GCN2 is essential for the murine immune system to adapt to amino acid deprivation by asparaginase.

Amino acid starvation by asparaginase (ASNase) enhances phosphorylation of eukaryotic initiation factor 2 (eIF2) by general control nonderepressible 2 (GCN2) kinase, leading to reduced global mRNA translation rates. This conserves energy and allows cells time to reprogram stress-related gene expression to alleviate cell injury. This study addressed the importance of GCN2 for the immune system to adapt to amino acid starvation by ASNase. GCN2(+/+) and GCN2(-/-) mice were injected once daily with ASNase or saline for up to 7 d. In both thymus and spleen, activation of amino acid stress response genes to ASNase, such as asparagine synthetase and CAAT enhancer binding protein homologous protein, required GCN2. ASNase reduced food intake and body weight in both genotypes, but spleen and thymus wet weights and total cell numbers in thymus, spleen, bone marrow, and mesenteric lymph nodes were less in GCN2(-/-) mice treated with ASNase (genotype x ASNase, P < 0.05). In the thymus, GCN2(-/-) mice treated with ASNase demonstrated enhanced apoptosis and fewer cells in all subpopulations examined (CD3+, CD4-8-, CD4+8+, CD4+8-, CD4-8+) compared with GCN2(+/+) mice treated with ASNase (genotype x ASNase, P < 0.05). In the spleen, GCN2 deletion magnified ASNase-induced reductions in CD4+ T cells, CD8+ T cells, CD19+ B cells, and CD11b+ leukocytes (genotype x ASNase, P < 0.05). These results indicate that loss of GCN2 enhances immunosuppression by ASNase and that this eIF2 kinase is broadly required for amino acid stress management in the immune system.

Acute pancreatitis in children with acute lymphoblastic leukemia treated with L-asparaginase.

BACKGROUND: L-asparaginase (L-asp) is used as part of the initial treatment in children with acute lymphoblastic leukemia (ALL), inducing remission in 83% to 95% of the treated patients. Major toxicity effects reported are hypersensitivity reactions and dysfunctions of the liver and pancreas. Acute pancreatitis (AP) induced by L-asp has been noted in 2.5% to 16% of the treated patients. The purpose of this study was to determine the frequency and outcome of AP in children with ALL treated with L-asp in a tertiary care pediatric hospital. METHODS: From January 1999 to June 2005, the charts of children with ALL admitted for L-asp treatment were reviewed. Data from children who developed AP were analyzed retrospectively. AP was defined as the presence of clinical data (nausea, vomiting, and abdominal pain), elevated pancreatic enzymes, and changes in the abdominal ultrasound and/or computed tomography (CT) scan. Clinical and biochemical data, abdominal ultrasound, and CT scan findings, complications, treatment, and outcome were analyzed retrospectively. RESULTS: During the last 6 years, 266 ALL new cases were started on chemotherapy including L-asp, of which 18 of 266 (6.7%) developed AP. Pancreatic necrosis by CT scan was found in 10 patients, peripancreatic collections and pseudocyst formation were detected in 5 and 3 cases, respectively, and resolved by cystogastrostomy or drainage. Two patients developed chronic pancreatitis and 3 diabetes. There was no relationship between number of doses and pancreatic toxicity. None of the patient died due to pancreatic toxicity. CONCLUSIONS: L-asp is an effective drug to treat ALL, the administration of L-asp requires the monitoring of pancreatic toxicity to detect AP and have treatment initiated as early as possible. Chronic complications after AP occur in almost one third of cases.

L-asparaginase in the treatment of refractory and relapsed extranodal NK/T-cell lymphoma, nasal type.

There is no standard salvage regimen for patients with refractory and relapsed extranodal NK/T-cell lymphoma (NKTCL), nasal type. This study was conduced to evaluate the efficacy of L-asparaginase-based regimen as a salvage regimen, on refractory and relapsed extranodal NKTCL, nasal type. Between March 1996 and March 2008, 45 patients with refractory and relapsed extranodal NKTCL, nasal type, were studied retrospectively. All patients were treated with L-asparaginase-based salvage regimen. Thirty-nine patients also received primary involved-field radiation after L-asparaginase-based chemotherapy. The complete response rate, partial response rate, and overall response rate for the whole group were 55.6%, 26.7%, and 82.2%, respectively. Both of 3-year and 5-year overall survival (OS) rates were 66.9%. The major adverse effects of L-asparaginase were myelosuppression, liver dysfunction, hyperglycemia, and allergic reaction. In general, the side effects could be tolerated. On univariate analysis, age, the stage of disease, and performance status were found to be prognostic factors influencing OS. On multivariate analysis, the stage of disease and age were independent prognostic factors for OS. L-Asparaginase-based regimen was obviously effective for the patients with refractory and relapsed extranodal NKTCL, nasal type.

A mouse model for glucocorticoid-induced osteonecrosis: effect of a steroid holiday.

Glucocorticoid-induced osteonecrosis is a common and dose-limiting adverse event. The goal of this study was to establish a mouse model of glucocorticoid-induced osteonecrosis suitable for testing the effects of different treatment strategies on its frequency. Fourteen murine strains were screened using various glucocorticoids, routes of administration, and diets. Four-week-old male BALB/cJ mice were treated with oral dexamethasone for up to 12 weeks either by continuous dosing or by discontinuous dosing, with or without asparaginase. Histopathological features of the distal femurs were examined by light microscopy. Osteonecrotic lesions were characterized by empty lacunae and osteocyte ghosts in trabecular bone surrounded by necrotic marrow and edema. The incidence of dexamethasone induced osteonecrosis in BALB/cJ mice was 40-45% (4/10 or 5/11) at 12 weeks. The frequency of osteonecrosis trended lower after discontinuous compared to continuous dosing for 12 weeks (8 vs. 45%) (p = 0.06) despite comparable cumulative plasma exposure. Asparaginase hastened the occurrence of osteonecrosis, which was observed as early as 4 weeks and the incidence was 50% after 6 weeks. A mouse model of glucocorticoid-induced osteonecrosis was established. Discontinuous was less osteonecrotic than continuous dexamethasone treatment, consistent with the possible benefits of a "steroid holiday" seen in clinical settings. Moreover, asparaginase hastened osteonecrosis, indicating that drugs may interact with glucocorticoids to affect osteonecrosis risk.