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Miraki-Moud F.,Queen Mary, University of London | Ghazaly E.,Queen Mary, University of London | Ariza-McNaughton L.,Cancer Research UK Research Institute | Hodby K.A.,Queen Mary, University of London | And 12 more authors.
Blood | Year: 2015

The strategy of enzymatic degradation of amino acids to deprive malignant cells of important nutrients is an established component of induction therapy of acute lymphoblastic leukemia. Here we show that acute myeloid leukemia (AML) cells from most patients with AML are deficient in a critical enzyme required for arginine synthesis, argininosuccinate synthetase-1 (ASS1). Thus, these ASS1-deficient AML cells are dependent on importing extracellular arginine. We therefore investigated the effect of plasma arginine deprivation using pegylated arginine deiminase (ADI-PEG 20) against primary AMLs in a xenograft model and in vitro. ADI-PEG 20 alone induced responses in 19 of 38 AMLs in vitro and 3 of 6 AMLs in vivo, leading to caspase activation in sensitive AMLs. ADI-PEG 20-resistant AMLs showed higher relative expression of ASS1 than sensitive AMLs. This suggests that the resistant AMLs survive by producing arginine through this metabolic pathway and ASS1 expression could be used as a biomarker for response. Sensitive AMLs showed more avid uptake of arginine from the extracellular environment consistent with their auxotrophy for arginine. The combination of ADI-PEG 20 and cytarabine chemotherapy was more effective than either treatment alone resulting in responses in 6 of 6 AMLs tested in vivo. Our data show that arginine deprivation is a reasonable strategy in AML that paves the way for clinical trials. © 2015 by The American Society of Hematology. Source

Syed N.,Imperial College London | Langer J.,Imperial College London | Janczar K.,Imperial College London | Singh P.,Imperial College London | And 10 more authors.
Cell Death and Disease | Year: 2013

Arginine deprivation, either by nutritional starvation or exposure to ADI-PEG20, induces adaptive transcriptional upregulation of ASS1 and ASL in glioblastoma multiforme ex vivo cultures and cell lines. This adaptive transcriptional upregulation is blocked by neoplasia-specific CpG island methylation in either gene, causing arginine auxotrophy and cell death. In cells with methylated ASS1 or ASL CpG islands, ADI-PEG20 initially induces a protective autophagic response, but abrogation of this by chloroquine accelerates and potentiates cytotoxicity. Concomitant methylation in the CpG islands of both ASS1 and ASL, observed in a subset of cases, confers hypersensitivity to ADI-PEG20. Cancer stem cells positive for CD133 and methylation in the ASL CpG island retain sensitivity to ADI-PEG20. Our results show for the first time that epigenetic changes occur in both of the two key genes of arginine biosynthesis in human cancer and confer sensitivity to therapeutic arginine deprivation. We demonstrate that methylation status of the CpG islands, rather than expression levels per se of the genes, predicts sensitivity to arginine deprivation. Our results suggest a novel therapeutic strategy for this invariably fatal central nervous system neoplasm for which we have identified robust biomarkers and which overcomes the limitations to conventional chemotherapy imposed by the blood/ brain barrier. © 2013 Macmillan Publishers Limited All rights reserved. Source

Yang T.-S.,Chang Gung University | Lu S.-N.,Kaohsiung Chang Gung Memorial Hospital | Chao Y.,Taipei Veterans General Hospital | Sheen I.-S.,Chang Gung University | And 11 more authors.
British Journal of Cancer | Year: 2010

Background:Human hepatocellular carcinoma (HCC) cells are largely deficient of argininosuccinate synthetase and thus auxotrophic for arginine. This study aims to investigate the efficacy and pharmacodynamics of pegylated arginine deiminase (ADI-PEG 20), a systemic arginine deprivation agent, in Asian HCC patients.Methods:Patients with advanced HCC who were not candidates for local therapy were eligible and randomly assigned to receive weekly intramuscular injections of ADI-PEG 20 at doses of 160 or 320 IU m 2. The primary end point was disease-control rate (DCR).Results:Of the 71 accruals, 43.6% had failed previous systemic treatment. There were no objective responders. The DCR and the median overall survival (OS) of the intent-to-treat population were 31.0% (95% confidence interval (CI): 20.5-43.1) and 7.3 (95% CI: 4.7-9.9) months respectively. Both efficacy parameters were comparable between the two study arms. The median OS of patients with undetectable circulating arginine for more than or equal to and 4 weeks was 10.0 (95% CI: 2.1-17.9) and 5.8 (95% CI: 1.4-10.1) months respectively (P0.251, log-rank test). The major treatment-related adverse events were grades 1-2 local and/or allergic reactions.Conclusions:ADI-PEG 20 is safe and efficacious in stabilising the progression of heavily pretreated advanced HCC in an Asian population, and deserves further exploration. © 2010 Cancer Research UK. All rights reserved. Source

Tomlinson B.K.,University of California at Davis | Thomson J.A.,Polaris Pharmaceuticals Inc. | Bomalaski J.S.,Polaris Pharmaceuticals Inc. | Diaz M.,Polaris Pharmaceuticals Inc. | And 10 more authors.
Clinical Cancer Research | Year: 2015

Purpose: This phase I study examined the toxicity and tolerability of pegylated arginine deiminase (ADI-PEG 20) in combination with docetaxel in patients with advanced solid malignancies. Experimental Design: Eligible patients had histologically proven advanced solid malignancies, with any number of prior therapies, Zubrod performance status 0-2, and adequate organ function. Patients received ADI-PEG 20 weekly intramuscular injection ranging from 4.5 to 36 mg/m2 and up to 10 doses of docetaxel (75 mg/m2) every 3 weeks. Primary endpoints were safety, toxicity, and a recommended phase II dose. Circulating arginine levels were measured before each cycle. Tumor response was measured as a secondary endpoint every 6 weeks on study. Results: Eighteen patients received a total of 116 cycles of therapy through four dose levels of ADI-PEG 20. A single doselimiting toxicity (grade 3 urticarial rash) was observed at the 1st dose level, with no additional dose-limiting toxicities observed. Hematologic toxicities were common with 14 patients experiencing at least one grade 3 to 4 leukopenia. Fatigue was the most prevalent toxicity reported by 16 patients. Arginine was variably suppressed with 10 patients achieving at least a 50% reduction in baseline values. In 14 patients with evaluable disease, four partial responses (including 2 patients with PSA response) were documented, and 7 patients had stable disease. Conclusions: ADI-PEG 20 demonstrated reasonable toxicity in combination with docetaxel. Promising clinical activity was noted, and expansion cohorts are now accruing for both castrate-resistant prostate cancer and non-small cell lung cancer at a recommended phase II dose of 36 mg/m2. © 2015 AACR. Source

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