RESUMEN
The alkylation products formed by in vitro treatment of DNA with tritium-labeled 1,3-bis(2-chloroethyl)-1-nitrosourea ((3)H-BCNU) were identified and quantified. Twelve adducts were resolved by high-performance liquid chromatography (HPLC). The principal DNA adducts formed by BCNU treatment corresponded to N-7-(2-hydroxyethyl)guanine (N7-HOEtG) (26%), N-7-(2-chloroethyl)guanine (15%), and phosphotriesters (19%). In addition, several minor products were identified as 1,2-(diguan-7-yl)ethane, N-1-(2-hydroxyethyl)-2-deoxyguanosine, 1-(N-1-2-deoxyguanosinyl), 2-(N-3-2-deoxycytidyl)ethane cross-link, and O-6-(2-hydroxyethyl)-2-deoxyguanosine, and individually they represented 1% to 5% of the total alkylation. An HPLC-electrochemical method was applied to quantify the levels of N7-HOEtG in samples treated with BCNU. Treatment of either purified DNA or U87MG cells with various amounts of BCNU produced a linear increase in the amount of N7-HOEtG. These results demonstrated that the levels of N7-HOEtG formed by BCNU treatment could be used as a molecular dosimeter of BCNU treatment dose. We measured the levels of N7-HOEtG in DNA isolated from tumor samples taken from four patients with GBM tumors following stereotactic intratumoral injection with DTI-015 (BCNU-ethanol). The level of N7-HOEtG in these samples ranged from 14.7 to 121.9 micromol N7-HOETG/mol DNA within 1 cm of the site of injection. As the distance from the site of injection increased, the levels of N7-HOEtG in tumor DNA decreased. In two of the samples, the levels of N7-HOEtG were 0.2 to 0.3 micromol N7-HOETG/mol DNA at 3.5 to 3.9 cm from the site of injection, demonstrating significant distribution of BCNU in the tumor. The levels of N7-HOEtG in these tumor samples corresponded to BCNU treatment concentrations of 0.02 to 43.0 mM. These studies demonstrate that stereotactic intratumoral injection of DTI-015 into human GBM tumors produces high concentrations of BCNU up to 2.5 cm from the site of injection in some of the tumors. These observations suggest that intratumoral injection of DTI-015 may be of benefit in the treatment of primary and recurrent GBM tumors.
Asunto(s)
Antineoplásicos Alquilantes/farmacocinética , Neoplasias Encefálicas/metabolismo , Carmustina/farmacocinética , Glioblastoma/metabolismo , Guanina/análogos & derivados , Antineoplásicos Alquilantes/metabolismo , Neoplasias Encefálicas/tratamiento farmacológico , Carmustina/metabolismo , Cromatografía Líquida de Alta Presión , Reactivos de Enlaces Cruzados , ADN de Neoplasias/metabolismo , Etanol , Glioblastoma/tratamiento farmacológico , Guanina/administración & dosificación , Humanos , Inyecciones Intralesiones , Células Tumorales CultivadasRESUMEN
Intratumoral (IT) administration of DTI-015 (BCNU in 100% ethanol) utilizes solvent facilitated perfusion for the treatment of tumors. RIF-1 tumors were treated by IT injection of either ethanol alone or 0.05-1.0 mg of DTI-015 or by i.v. injection of 0.5 mg of BCNU. Treatment with ethanol alone or i.v. injection of 0.5 mg of BCNU did not produce a significant growth delay. In contrast, IT administration of DTI-015 produced a significant growth delay at each of the treatment doses (p < 0.05 to p < 0.001). We have quantified the levels of N7-(2-hydroxyethyl) guanine (N7-HOEtG) in RIF-1 tumors 24h following either IT treatment with 0.5 mg DTI-015 or i.p. administration of 0.5 mg BCNU. Levels of N7-HOEtG (micromol/mol DNA) were < or = 0.08 for both untreated controls and following i.p. treatment with BCNU and 13.1 +/- 5.6 following IT administration of DTI-015. The levels of N7-HOEtG detected in RIF-1 tumors following IT administration of DTI-015 were 164-fold higher than the level(s) of N7-HOEtG in the i.p. BCNU treated tumor samples. These studies demonstrate that IT administration of DTI-015 produces high levels of DNA adducts in the tumor which correspond to a significant increase in tumor growth delay compared to the same dose of BCNU administered systemically.