Quantitation of 6-thioguanine residues in peripheral blood leukocyte DNA obtained from patients receiving 6-mercaptopurine-based maintenance therapy.
Cancer Res
; 55(8): 1670-4, 1995 Apr 15.
Article
em En
| MEDLINE
| ID: mdl-7712473
ABSTRACT
The antimetabolite 6-mercaptopurine is widely utilized in maintenance therapy for childhood acute lymphoblastic leukemia. Following p.o. administration, this prodrug undergoes extensive biotransformation, resulting in the generation of a plethora of metabolites including 2'-deoxy-6-thioguanosine triphosphate. Incorporation of 6-thioguanine (6-TG) bases into DNA is generally considered to be central to thiopurine-mediated cytotoxicity. We have developed a novel precolumn derivatization HPLC technique for quantifying 6-TG base accumulation into leukocyte DNA obtained from acute lymphoblastic leukemia patients receiving 6-mercaptopurine maintenance therapy. The method is based on enzymatic degradation of DNA to 2'-deoxyribonucleosides and the derivatization of released 2'-deoxy-6-thioguanosine with a thiol-reactive reagent containing a 7-amino-4-methylcoumarin-3-acetic acid fluorophore. The 2'-deoxy-6-thioguanosine-7-amino-4-methylcoumarin-3-acetic acid adduct is resolved by reversed-phase HPLC and quantified fluorometrically. Assay response is linear from 15 pmol to 60 fmol 6-TG bases/microgram DNA with a limit of quantitation corresponding to the incorporation of 1 6-TG residue per 50,000 bases. In a small cohort of acute lymphoblastic leukemia patients receiving p.o. 6-mercaptopurine-based maintenance therapy, significant interindividual variation in the accumulation of 6-TG bases into leukocyte DNA was revealed. The determined levels of drug base incorporation ranged from 95 to 710 fmol 6-TG bases/microgram DNA (6-TG basenucleotide ratio 132,000 to 14,000). The assay may provide a novel methodology for pharmacological monitoring of thiopurine therapy either in the routine clinical setting or during studies of alternative routes of drug delivery.
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Coleções:
01-internacional
Temas:
Geral
/
Tipos_de_cancer
/
Outros_tipos
Base de dados:
MEDLINE
Assunto principal:
Tioguanina
/
DNA
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DNA de Neoplasias
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Leucemia-Linfoma Linfoblástico de Células Precursoras
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Leucócitos
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Mercaptopurina
Limite:
Child
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Humans
Idioma:
En
Revista:
Cancer Res
Ano de publicação:
1995
Tipo de documento:
Article