Characterization of Dasatinib and Its Structural Analogs as CYP3A4 Mechanism-Based Inactivators and the Proposed Bioactivation Pathways

Li, Xiaohai; He, Yuanjun; Ruiz, Claudia; Koenig, Marcel; Cameron, Michael D.

doi:10.1124/dmd.108.025932

Cited by 113 publications

(116 citation statements)

References 31 publications

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“…For conjugates 1 and 2, conjugation at the methyl is likely to occur through the formation of a quinone methide intermediate. While this has been observed previously in GST conjugation to methyl-substituted aromatic rings (Kassahun et al, 2001;Li et al, 2009), this is, to our knowledge, the first report of such a GST conjugate to TNT. For both GST-U24 and GST-U25, catalytic activity increased with pH, with the optimum appearing to be pH 9.5 or greater.…”

Section: Glutathione-tnt Productsmentioning

confidence: 42%

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

et al. 2014

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The explosive 2,4,6-trinitrotoluene (TNT) is a major worldwide military pollutant. The presence of this toxic and highly persistent pollutant, particularly at military sites and former manufacturing facilities, presents various health and environmental concerns. Due to the chemically resistant structure of TNT, it has proven to be highly recalcitrant to biodegradation in the environment. Here, we demonstrate the importance of two glutathione transferases (GSTs), GST-U24 and GST-U25, from Arabidopsis (Arabidopsis thaliana) that are specifically up-regulated in response to TNT exposure. To assess the role of GST-U24 and GST-U25, we purified and characterized recombinant forms of both enzymes and demonstrated the formation of three TNT glutathionyl products. Importantly, GST-U25 catalyzed the denitration of TNT to form 2-glutathionyl-4,6-dinitrotoluene, a product that is likely to be more amenable to subsequent biodegradation in the environment. Despite the presence of this biochemical detoxification pathway in plants, physiological concentrations of GST-U24 and GST-U25 result in only a limited innate ability to cope with the levels of TNT found at contaminated sites. We demonstrate that Arabidopsis plants overexpressing GST-U24 and GST-U25 exhibit significantly enhanced ability to withstand and detoxify TNT, properties that could be applied for in planta detoxification of TNT in the field. The overexpressing lines removed significantly more TNT from soil and exhibited a corresponding reduction in glutathione levels when compared with wild-type plants. However, in the absence of TNT, overexpression of these GSTs reduces root and shoot biomass, and although glutathione levels are not affected, this effect has implications for xenobiotic detoxification.The containment and cleanup of environmental pollutants is increasingly both a legal requirement and a responsible action in many developed countries. The most commonly used explosives in military weapons are 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and their continual use, along with production and decommissioning, are progressively contaminating millions of hectares of military land . Bioremediation of TNT is particularly challenging, as the electron-withdrawing properties of the three nitro groups render the aromatic ring particularly resistant to oxidative attack and ring cleavage by microbial oxygenases, which in the environment are normally central to the biodegradation of aromatic compounds (Qasim et al., 2007). In the United States, the Environmental Protection Agency and the military are addressing methods by which toxic TNT and RDX can be contained and detoxified on active military training ranges. One way this problem might be tackled is through the use of plants that are adapted to detoxify these compounds. This could be achieved either by traditional breeding programs or by genetic modification, as has been demonstrated previously for both RDX and TNT (Hannink et al., 2001;Rylott et al., 2006;Jackson et al., 2007).In t...

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Section: Glutathione-tnt Productsmentioning

confidence: 42%

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

et al. 2014

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“…As these drugs can inactivate CYP3A4, the enzyme responsible for the oxidation of BU after initially being conjugated with glutathione, the hypothesis that tyrosine kinase inhibitors could affect BU metabolism cannot be excluded. [15][16][17][18] Variations in BU AUC have been previously observed in approximately 20% of the patients. 3,6,7,11,12 In particular, these variations were higher in a pediatric population with rapidly changing metabolism, 13 and the test dose was used to address this problem before a reduced-intensity conditioning HSCT.…”

Section: Discussionmentioning

confidence: 99%

Reliability of a pretransplant i.v. BU test dose performed 2 weeks before myeloablative FluBu conditioning regimen

Beri

Chunduri

Sweiss

et al. 2009

Bone Marrow Transplant

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A pretransplant test dose of i.v. BU was previously used in pediatric patients undergoing a reduced-intensity allogeneic hematopoietic SCT (HSCT). Here, we used a BU test dose in 23 adult patients who were not pancytopenic and underwent a myeloablative allogeneic HSCT prepared with fludarabine and i.v. BU (FluBU). Pharmacokinetics (PK) of BU were calculated after a test dose (0.8 mg/kg) was performed 2 weeks before transplant. Targeted BU area under the curve (AUC) range was 4800-5200 lM min. The mean BU dose calculated after the test dose was 3.5 ± 0.5 mg/kg. To validate the test dose, PK studies were repeated in 17 patients after the first dose of BU during the conditioning regimen. An AUC below the therapeutic value of 4000 lM min was observed in 23% of the patients receiving a wt-based dose and in 0% of patients whose dose was calculated on the basis of the test dose (P ¼ 0.03). In patients who had a test dose, a significant correlation (Po0.0001) between the first and subsequent doses of BU during the conditioning regimen was observed. Our findings may allow more centers to pursue transplant strategies with targeted BU by overcoming the time limitation for PK studies during the conditioning regimen.

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“…For example, erlotinib and dasatinib are mechanism-based inactivators of CYP3A [15,16], a characteristic of many important inhibitors of drug metabolism [17,18]. Product information for these drugs indicates minor impact on the clearance of CYP3A substrates [Sprycel® (dasatinib), labelling,Tarceva® (erlotinib) labelling], but these data are not in the public domain.…”

Section: Discussionmentioning

confidence: 99%

Perpetrators of pharmacokinetic drug–drug interactions arising from altered cytochrome P450 activity: a criteria‐based assessment

Polasek

Lin

Miners

et al. 2011

Brit J Clinical Pharma

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WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Many drugs inhibit or induce cytochrome P450 enzymes (CYP) to cause clinically significant changes in the concentrations of other drugs, i.e.'perpetrate' pharmacokinetic drug-drug interactions (PK-DDIs).• Tables that list the substrates, inhibitors and inducers of CYP are common, but they lack consistency and are constructed from evidence of variable quality. WHAT THIS STUDY ADDS• This is the first study to catalogue important perpetrators of PK-DDIs using objective criteria and clinical pharmacokinetic drug interaction studies. This information is intended to inform clinical decisions on PK-DDIs.• Existing tables of CYP inhibitors and inducers have low sensitivity and low positive predictive value in identifying the major perpetrators of PK-DDIs. • Several drugs were identified which potentially perpetrate CYP-mediated PK-DDIs, but quality clinical pharmacokinetic interaction studies are lacking. This information may be used to inform future research. AIMSTo catalogue the perpetrators of CYP-mediated pharmacokinetic drug-drug interactions (PK-DDIs) using clinically relevant criteria, and to compare this with an analogous catalogue. METHODSCandidate inhibitors and inducers of CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A ('perpetrators') were evaluated using published clinical pharmacokinetic interaction studies. Studies were selected on the basis of Նsix human subjects, use of a validated in vivo probe substrate for the CYP enzyme, and clinically relevant dosing. Inhibitors were described according to the FDA classifications of strong, moderate or weak, whereas inducers were classified as major (Նtwofold decrease in AUC) or weak (

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Characterization of Dasatinib and Its Structural Analogs as CYP3A4 Mechanism-Based Inactivators and the Proposed Bioactivation Pathways

Cited by 113 publications

References 31 publications

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

Arabidopsis Glutathione Transferases U24 and U25 Exhibit a Range of Detoxification Activities with the Environmental Pollutant and Explosive, 2,4,6-Trinitrotoluene

Reliability of a pretransplant i.v. BU test dose performed 2 weeks before myeloablative FluBu conditioning regimen

Perpetrators of pharmacokinetic drug–drug interactions arising from altered cytochrome P450 activity: a criteria‐based assessment

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