L-Asparaginase e perspectivas no tratamento da leucemia linfoblástica aguda: revisão de literatura / L-Asparaginase and perspectives in the treatment of leukemia acute lymphoblastic: literature review

Introdução: A L-asparaginase tem sido estudada como alternativa no tratamento da Leucemia Linfoblástica Aguda (LLA) uma vez que possui a capacidade de induzir apoptose em células leucêmicas sem causar danos às células normais. Estudos mostraram benefícios no tratamento da LLA, porém com o risco de desenvolver efeitos adversos. Objetivo: Este trabalho visa apresentar e explicar o histórico da L-asparaginase, desafios enfrentados pelo Brasil, mecanismos de ação que envolvem as formas da enzima e efeitos adversos de sua utilização. Métodos: Foram incluídos neste trabalho 54 artigos na língua portuguesa e inglesa consultados em bancos de artigos como PubMed e SciELO, entre o período de 1953 até 2021. Resultados: A L-asparaginase é uma enzima que converte asparagina em aspartato e amônia, isolada a partir de colônias de Escherichia coli e de Erwinia chrysanthemi, além disso foi polimerizada com polietilenoglicol. O uso de corticosteroides, anti-histamínicos e suplementação vitamínica se mostraram eficientes para amenizar os efeitos adversos. Conclusões: É necessário evitar um desabastecimento de L-Asparaginase no Brasil, principalmente por conta da dificuldade de comercialização e alto custo, mesmo sendo um medicamento presente na lista da Organização Mundial da Saúde, considerado essencial.

Introduction: L-asparaginase has been studied as an alternative in the treatment of Acute Lymphoblastic Leukemia (ALL) since it has the ability to induce apoptosis in leukemic cells without causing damage to normal cells. Studies have shown benefits in the treatment of ALL, but with the risk of developing adverse effects. Objective: This work aims to present and explain the history of L-asparaginase, challenges faced by Brazil, mechanisms of action involving the forms of the enzyme and adverse effects of its use. Methods: 54 articles in Portuguese and English were included in this work, consulted in article banks such as PubMed and SciELO, between the period of 1953 to 2021. Results: L-asparaginase is an enzyme that converts asparagine into aspartate and ammonia, isolated from from Escherichia coli and Erwinia chrysanthemi colonies, it was also polymerized with polyethylene glycol. The use of corticosteroids, antihistamines and vitamin supplementation proved to be efficient in mitigating adverse effects. Conclusions: It is necessary to avoid a shortage of L-Asparaginase in Brazil, mainly due to the difficulty of commercialization and high cost, even though it is a drug present on the World Health Organization list, considered essential.

Correlation of L-asp Activity, Anti-L-asp Antibody, Asn and Gln With Adverse Events Especially Anaphylaxis Risks in PEG-asp-Contained Regime Treated Pediatric ALL Patients.

OBJECTIVE: This study aimed to investigate the correlation of L-asparaginase (L-asp) activity, anti-L-asp antibody, asparagine and glutamine levels with the risks of adverse events (AEs), especially anaphylaxis, in pediatric acute lymphoblastic leukemia (ALL) patients who underwent polyethylene glycol-conjugated L-asp (PEG-asp)-contained treatment. METHODS: Plasma samples were collected from 91 pediatric ALL patients who underwent PEG-asp-contained treatment on the 7th day after drug administration. Plasma L-asp activity, anti-L-asp antibody level, asparagine level and glutamine level were detected. Meanwhile, AEs related to PEG-asp administration were recorded. RESULTS: AEs occurred in 13 (14.3%) patients, among which 7 (7.7%) patients had anaphylaxis, while another 6 patients had non-anaphylaxis AEs (including 4 (4.4%) patients who had acute pancreatitis, 1 (1.1%) patient who had abdominal pain and diarrhea, as well as 1 (1.1%) patient who had nausea and vomiting). L-asp activity was decreased, while asparagine and glutamine levels were increased in patients with AEs compared to patients without AEs, and ROC curves showed that they were correlated with higher AEs risk. Notably, further analyses revealed that L-asp activity, anti-L-asp antibody, asparagine and glutamine levels were highly correlated with anaphylaxis risk, but they were not associated with the risk of non-anaphylactic AEs. CONCLUSION: The measurement of L-asp activity, anti-L-asp antibody level, asparagine level and glutamine level might assist the prevention of anaphylaxis-related AEs in pediatric ALL patients who underwent PEG-asp-contained treatment.

Identification and validation of l-asparaginase as a potential metabolic target against Mycobacterium tuberculosis.

Multidrug-resistant Mycobacterium tuberculosis (Mtb) has emerged as a major health challenge, necessitating the search for new molecular targets. A secretory amidohydrolase, l-asparaginase of Mtb (MtA), originally implicated in nitrogen assimilation and neutralization of acidic microenvironment inside human alveolar macrophages, has been proposed as a crucial metabolic enzyme. To investigate whether this enzyme could serve as a potential drug target, it was studied for structural details and active site-specific inhibitors were tested on cultured Mycobacterial strain. The structural details of MtA obtained through comparative modeling and molecular dynamics simulations provided insights about the orchestration of an alternate reaction mechanism at the active site. This was contrary to the critical Tyr flipping mechanism reported in other asparaginases. We report the novel finding of Tyr to Val replacement in catalytic triad I along with the structural reorganization of a ß-hairpin loop upon substrate binding in MtA active site. Further, 5 MtA-specific, active-site-based inhibitors were obtained by following a rigorous differential screening protocol. When tested on Mycobacterium culture, 3 of these, M3 (ZINC 4740895), M26 (ZINC 33535), and doxorubicin showed promising results with inhibitory concentrations (IC 50 ) of 431, 100, and 56 µM, respectively. Based on our findings and considering stark differences with human asparaginase, we project MtA as a promising molecular target against which the selected inhibitors may be used to counteract Mtb infection effectively.

Expression and purification of L-asparaginase from Escherichia coli and the inhibitory effects of cyclic dipeptides.

L-asparaginase, a key enzyme involved in nitrogen metabolism, is an effective anti-tumour agent. Cyclic dipeptides, a group of compounds, contain several important biological functions. In this paper, we proposed a novel method for L-asparaginase expression and purification from Echerichia coli and determined the effect of cyclic dipeptides on the enzymatic activity of recombinant L-asparaginase. The gene ansB encoding L-asparaginase was amplified from the genome of E. coli BL21 (DE3) by polymerase chain reaction and sub-cloned into pET-15b vector to construct expressing plasmid pET-15b-ansB. The expression of recombinant protein was purified by affinity chromatography using a nickel resin followed by anion exchange chromatography. The purity and quality of the recombinant L-asparaginase were optimised. The results indicated that km for the recombinant L-asparaginase was 3.02 × 10-4 mol/L. Both cyclo-(Pro-Tyr) and cyclo-(Pro-Phe) could inhibit the activity of recombinant L-asparaginase at the level of 10-5 mol/L.

Impact of anti-PEG IgM antibodies on the pharmacokinetics of pegylated asparaginase preparations in mice.

The potential impact of pre-existing anti-PEG antibodies on the asparaginase activity kinetics of two pegylated l-asparaginase preparations - pegylated recombinant l-asparaginase (PEG-rASNase MC0609) and pegaspargase (pegylated Escherichia colil-asparaginase) - was investigated in immune competent, naïve B6D2F1-hybrid mice. To generate anti-PEG antibodies, mice were pre-sensitised by repeated injections of 40kDa PEG-Diol without being conjugated to a carrier. Successful PEG-Diol pre-sensitisation was verified by analysis of anti-PEG antibody titers in serum. 88-100% of animals developed PEG-specific anti-PEG IgM antibodies after PEG-Diol pre-sensitisation. All animals positive for anti-PEG IgM antibodies and control animals (without prior PEG-Diol pre-sensitisation) were treated once with PEG-rASNase MC0609 or pegaspargase, and asparaginase enzyme activity levels and immunogenicity of both preparations were analysed. Known serum asparaginase activity profiles were measured after treatment with PEG-rASNase MC0609 or pegaspargase in all treatment groups. No rapid decrease of asparaginase activity was observed - irrespective of successful PEG-Diol pre-sensitisation and presence of acquired anti-drug-IgG and/or anti-PEG IgM antibodies. In conclusion, the pharmacokinetics of pegylated l-asparaginase was unaffected by the presence of pre-existing anti-PEG IgM antibodies in immune competent B6D2F1-hybrid mice Probably the titre or affinity of these anti-PEG IgM antibodies were too low to influence the pharmacokinetics of PEG-rASNase MC0609 or pegaspargase or anti-PEG IgM antibodies bound to PEG-ASNase without neutralising capabilities. Thus, early loss of asparaginase activity as observed in serum of ALL patients is a complex process and cannot be explained solely by the existence of pre-existing anti-PEG antibodies.

Consensus expert recommendations for identification and management of asparaginase hypersensitivity and silent inactivation.

L-asparaginase is an integral component of therapy for acute lymphoblastic leukemia. However, asparaginase-related complications, including the development of hypersensitivity reactions, can limit its use in individual patients. Of considerable concern in the setting of clinical allergy is the development of neutralizing antibodies and associated asparaginase inactivity. Also problematic in the use of asparaginase is the potential for the development of silent inactivation, with the formation of neutralizing antibodies and reduced asparaginase activity in the absence of a clinically evident allergic reaction. Here we present guidelines for the identification and management of clinical hypersensitivity and silent inactivation with Escherichia coli- and Erwinia chrysanthemi- derived asparaginase preparations. These guidelines were developed by a consensus panel of experts following a review of the available published data. We provide a consensus of expert opinions on the role of serum asparaginase level assessment, indications for switching asparaginase preparation, and monitoring after change in asparaginase preparation.

L-Asparaginase as a new molecular target against leishmaniasis: insights into the mechanism of action and structure-based inhibitor design.

l-Asparaginases belong to a family of amidohydrolases that catalyze the conversion of l-asparagine into l-aspartic acid and ammonia. Although bacterial l-asparaginases have been used extensively as anti-leukemic agents, their possible role as potential drug targets for pathogenic organisms has not been explored. The presence of genes coding for putative l-asparaginase enzymes in the Leishmania donovani genome hinted towards the specific role of these enzymes in extending survival benefit to the organism. To investigate whether this enzyme can serve as a potential drug target against the Leishmania pathogen, we obtained structural models of one of the putative Leishmania l-asparaginase I (LdAI). Using an integrated computational approach involving molecular modelling, docking and molecular dynamics simulations, we found crucial differences between catalytic residues of LdAI as compared to bacterial l-asparaginases. The deviation from the canonical acid-base pair at triad I, along with the structural reorganization of a ß-hairpin loop in the presence of a substrate, indicated an altogether new mechanism of action of the LdAI enzyme. Moreover, the finding of compositional and functional differences between LdAI and human asparaginase was used as a criterion to identify specific small molecule inhibitors. Through virtual screening of a library of 11 438 compounds, we report five compounds that showed favorable interactions with the active pocket of LdAI, without adversely affecting human asparaginase. One of these compounds when tested on cultured Leishmania promastigotes displayed a promising leishmanicidal effect. Overall, our work not only provides first hand mechanistic insights of LdAI but also proposes five strongly active compounds which may prove as effective anti-leishmaniasis molecules.

A multicenter, open-label, Phase 1 study evaluating the safety and tolerability of pegaspargase in combination with gemcitabine in advanced metastatic solid tumors and lymphoma.

PURPOSE: To evaluate the maximum tolerated dose, safety profile, pharmacokinetics, and pharmacodynamics of pegaspargase (PEG-ASP) in combination with gemcitabine in patients with advanced metastatic solid tumors and lymphoma. METHODS: We conducted a multicenter, open label, nonrandomized, Phase 1 dose escalation study designed to evaluate up to 10 cohorts of patients with advanced or metastatic solid tumors and lymphoma. Seventeen patients were treated with of PEG-ASP in combination with gemcitabine. RESULTS: The study was terminated early because the doses for PEG-ASP suggested for de-escalation were predicted not to provide desired sustained asparaginase concentrations based on the analysis of treated patients.

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.

Anticancer properties of highly purified L-asparaginase from Withania somnifera L. against acute lymphoblastic leukemia.

Withania somnifera L. has been traditionally used as a sedative and hypnotic. The present study was carried out for the purification, characterization, and in vitro cytotoxicity of L-asparaginase from W. somnifera L. L-Asparaginase was purified from the fruits of W. somnifera L. up to 95% through chromatography. The purified L-asparaginase was characterized by size exclusion chromatography, polyacrylamide gel electrophoresis (PAGE), and 2D PAGE. The antitumor and growth inhibition effect of the L-asparaginase was assessed using [3-(4, 5-dimethyl-thiazol-2yl)-2, 5-diphenyl-tetrazolium bromide] (MTT) colorimetric dye reduction method. The purified enzyme is a homodimer, with a molecular mass of 72 +/- 0.5 kDa, and the pI value of the enzyme was around 5.1. This is the first report of the plant containing L-asparaginase with antitumor activity. Data obtained from the MTT assay showed a LD(50) value of 1.45 +/- 0.05 IU/ml. W. somnifera L. proved to be an effective and a novel source of L: -asparaginase. Furthermore, it shows a lot of similarity with bacterial L-asparaginases EC-2.

Cell growth stimulation by CRASH, an asparaginase-like protein overexpressed in human tumors and metastatic breast cancers.

The gene encoding CRASH, a human asparaginase-like protein, has been cloned and its transcriptional activation has been detected in gynecologic cancers. To define the expression of CRASH in human tumors and its possible functional role, monoclonal antibodies against the CRASH protein have been generated. In non-transformed tissues CRASH was only detected in testis, brain, esophagus, prostate and proliferating endometrium. On the other hand, 36/50 ovarian carcinomas, 16/78 mammary carcinomas, 6/6 uroepithelial bladder carcinomas and 5/33 colon carcinomas scored positive for CRASH, with the absence of reactivity in the corresponding normal tissues. Strikingly, 11 out of the 16 breast cancers that expressed CRASH were metastatic, nominating CRASH to be functionally relevant in tumor progression. Twenty-eight out of 42 endometrium tumors expressed CRASH at high levels as did 5/41 prostate carcinomas, as well as ovary and breast cancers, indicating a regulation of CRASH expression by sex hormones. A bona fide estrogen responsive element was detected at bases -201/-183. This proved to be highly preserved across species, supporting an actual functional role. Asparaginase-like proteins play a role in growth regulation and signaling by p70 S6 kinase. The somatic knock-out of CRASH resulted in significant inhibition of growth of KM12L4A colon carcinoma cells, which abundantly express CRASH, whereas the proliferation of the syngeneic, weakly-expressing, slowly-growing KL12SM was not affected. These results are consistent with a selective growth advantage for aggressive cancers expressing CRASH, and nominate CRASH as a novel diagnostic and therapeutic tumor target.

Engineering thermal stability of L-asparaginase by in vitro directed evolution.

L-asparaginase (EC 3.5.1.1, L-ASNase) catalyses the hydrolysis of l-Asn, producing L-Asp and ammonia. This enzyme is an anti-neoplastic agent; it is used extensively in the chemotherapy of acute lymphoblastic leukaemia. In this study, we describe the use of in vitro directed evolution to create a new enzyme variant with improved thermal stability. A library of enzyme variants was created by a staggered extension process using the genes that code for the L-ASNases from Erwinia chrysanthemi and Erwinia carotovora. The amino acid sequences of the parental L-ASNases show 77% identity, but their half-inactivation temperature (T(m)) differs by 10 degrees C. A thermostable variant of the E. chrysamthemi enzyme was identified that contained a single point mutation (Asp133Val). The T(m) of this variant was 55.8 degrees C, whereas the wild-type enzyme has a T(m) of 46.4 degrees C. At 50 degrees C, the half-life values for the wild-type and mutant enzymes were 2.7 and 159.7 h, respectively. Analysis of the electrostatic potential of the wild-type enzyme showed that Asp133 is located at a neutral region on the enzyme surface and makes a significant and unfavourable electrostatic contribution to overall stability. Site-saturation mutagenesis at position 133 was used to further analyse the contribution of this position on thermostability. Screening of a library of random Asp133 mutants confirmed that this position is indeed involved in thermostability and showed that the Asp133Leu mutation confers optimal thermostability.

FDA drug approval summary: pegaspargase (oncaspar) for the first-line treatment of children with acute lymphoblastic leukemia (ALL).

On July 24, 2006, the U.S. Food and Drug Administration granted approval to pegaspargase (Oncaspar; Enzon Pharmaceuticals, Inc., Bridgewater, NJ; hereafter, O) for the first-line treatment of patients with acute lymphoblastic leukemia (ALL) as a component of a multiagent chemotherapy regimen. O was previously approved in February 1994 for the treatment of patients with ALL who were hypersensitive to native forms of L-asparaginase. The trial supporting this new indication was an open label, randomized, multicenter clinical trial that enrolled 118 children (age, 1-9 years) with previously untreated, standard risk ALL. Patients received either native Escherichia coli asparaginase (Elspar; Merck, Whitehouse Station, NJ; hereafter, E) or O along with multiagent chemotherapy during remission induction and delayed intensification (DI) phases of treatment. O, at a dose of 2,500 IU/m(2), was administered i.m. on day 3 of the 4-week induction phase and on day 3 of each of two 8-week DI phases. E, at a dose of 6,000 IU/m(2), was administered i.m. three times weekly for nine doses during induction and for six doses during each DI phase. This study allowed direct comparison of O and E for asparagine depletion, asparaginase activity, and development of asparaginase antibodies. An unplanned comparison of event-free survival (EFS) was conducted to rule out a deleterious O efficacy effect. Following induction and DI treatment there was complete (0.03 IU/ml in O-treated subjects was greater than the number of days in E-treated subjects during both the induction and DI phases of treatment. There was no correlation, however, between asparaginase activity and serum asparagine levels, making the former determination less clinically relevant. Using the protocol-prespecified threshold for a positive result of >2.5 times the control, 7 of 56 (12%) O subjects tested at any time during the study demonstrated antiasparaginase antibodies and 16 of 57 (28%) E subjects tested at any time during the study had antiasparaginase antibodies. In both study arms EFS was in the range of 80% at 3 years. The most serious, sometimes fatal, O toxicities were anaphylaxis, other serious allergic reactions, thrombosis (including sagittal sinus thrombosis), pancreatitis, glucose intolerance, and coagulopathy. The most common adverse events were allergic reactions (including anaphylaxis), hyperglycemia, pancreatitis, central nervous system thrombosis, coagulopathy, hyperbilirubinemia, and elevated transaminases. Disclosure of potential conflicts of interest is found at the end of this article.

Effective gene suppression using small interfering RNA in hard-to-transfect human T cells.

RNA interference (RNAi) is an evolutionarily conserved cellular defense mechanism that protects cells from hostile genes and regulates the function of normal genes during growth and development. In this study, we established proof of principle of small interfering RNA (siRNA) silencing in hard-to-transfect human T cell lines and primary human CD4 T cells. We used public and in-house programs to design four siRNAs each for GFP, for our novel cellular gene HALP, and for their corresponding scrambled siRNA controls. We generated siRNA expression cassettes (SECs) by PCR and directly transfected the PCR products into T cells using amaxa Nucleofector technology. The most effective SECs were selected and cloned into a TA cloning vector and titered with their respective controls to increase transfection efficiency. Flow cytometry and fluorescence microscopy analyses were performed for GFP siRNAs, and Northern blot analysis was done to assess the HALP silencing effect. These experiments demonstrate that SECs are an excellent screening tool to identify siRNA sequences effective in silencing expression of genes of interest. The vector expressing the most effective siRNA robustly inhibited GFP expression (up to 92%) in the context of co-transfection in human T cell lines and primary CD4 T cells. The optimized siRNA for our endogenous cellular gene HALP also silenced its target RNA expression by more than 90%. These studies demonstrate that the combination of SEC, siRNA expression vectors and Nucleofector technology can be successfully applied to hard-to-transfect human T cell lines and primary T cells to effectively silence genes.

Isolation and characterization of Enterobacter cloacae capable of metabolizing asparagine.

A gram-negative, rod-shaped bacterium capable of utilizing L-asparagine as its sole source of carbon and nitrogen was isolated from soil and identified as Enterobacter cloacae. An intracellularly expressed L-asparaginase was detected and it deaminated L-asparagine to aspartic acid and ammonia. High-pressure liquid chromatography analysis of a cell-free asparaginase reaction mixture indicated that 2.8 mM L-asparagine was hydrolyzed to 2.2 and 2.8 mM aspartic acid and ammonia, respectively, within 20 min of incubation. High asparaginase activity was found in cells cultured on L-fructose, D-galactose, saccharose, or maltose, and in cells cultured on L-asparagine as the sole nitrogen source. The pH and temperature optimum of L-asparaginase was 8.5 and 37-42 degrees C, respectively. The half-life of the enzyme at 30 degrees C and 37 degrees C was 10 and 8 h, respectively.

Why a "benign" mutation kills enzyme activity. Structure-based analysis of the A176V mutant of Saccharomyces cerevisiae L-asparaginase I.

A conservative and apparently harmless A176V mutation in intracellular S. cerevisiae L-asparaginase (ScerAI) completely abolishes the enzyme activity. Sequence and structural comparisons with type II bacterial L-asparaginases show that the mutated residue is in a very conservative region and plays a vital role in the cohesion of functional tetramers of these enzymes through participation in side-chain...main-chain (Ser) Oy...O (Ala) hydrogen bonds across the tetramer interface. The fact that bacterial L-asparaginases of type I show less conservation in this region suggests that they may have different quaternary structure while adopting the subunit fold and intimate dimer architecture of type II enzymes. A comparison of all available sequences of microbial L-asparaginases confirms that separate intra- and extra-cellular enzymes evolved in prokaryotes and eukaryotes independently. However, an analysis of the available complete genome sequences reveals a surprising fact that Haemophilus influenzae possesses only a type II asparaginase while the archaebacterium Methanococcus jannaschii has a type I gene, but not a type II.

Determination of L-asparagine in biological samples in the presence of L-asparaginase.

The antileukaemic efficacy of L-asparaginase is related to the ability of the enzyme to induce the complete disappearance from plasma of L-asparagine, an amino acid essential to lymphoblastic leukaemia cells. It is not feasible to monitor L-asparagine plasma levels in patients under L-asparaginase treatment using the usual analytical procedures as the enzyme continues the hydrolysis of L-asparagine after blood sampling and during plasma extraction. A method was therefore developed for the determination of L-asparagine in patients receiving L-asparaginase. Sulphosalicylic acid is added to blood samples to deproteinize and inactivate L-asparaginase rapidly. The samples are then analysed by HPLC using a Novapack C18 column and fluorescence detection. With the same method L-asparagine is determined in blood cells and, by difference, plasma levels are calculated. This method is highly specific and sufficiently simple and sensitive for clinical use.