Intraarterial O6-benzylguanine enables the specific therapy of nitrosourea resistant intracranial human glioma xenografts in athymic rats with 1,3-bis(2-chloroethyl)-1-nitrosourea

Shekar N. Kurpad, M. Eileen Dolan, Roger E. McLendon, Gerald E. Archer, Robert C. Moschel, Anthony E. Pegg, Darell D. Bigner, Henry S. Friedman

Research output: Contribution to journalArticle

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Abstract

The prognosis for patients with malignant gliomas continues to be dismal. The high degree of resistance of gliomas to nitrosourea-based chemotherapy is one major factor in poor treatment outcome. The identification of O6-alkylguanine-DNA alkyltransferase (AGAT) as a major determinant of nitrosourea resistance has resulted in the development of several agents to inactivate this repair protein and counteract tumor cell resistance. However, a major problem in preclinical trials has been the marked nitrosourea dose limitations imposed by the prior administration of AGAT-depleting agents. We investigated the AGAT depletion and selective enhancement of BCNU activity of intraarterial (i.a.) O6-benzylguanine (O6BG) in the human malignant glioma xenograft D-456 MG growing intracranially (i.c.) in athymic rats. Whereas i.a. O6BG at 2.5 mg/kg produced 100% inhibition of D-456 MG AGAT i.c. activity 8 h after administration, intraperitoneal (i.p.) O6BG at this dose produced only 40% inhibition, requiring dose escalation to 10 mg/kg to produce 100% AGAT depletion. Prior administration of i.p. O6BG (10 mg/kg) and i.a. O6BG (2.5 mg/kg) limited maximum tolerated intravenous (i.v.) BCNU doses (37.5 mg/kg when given alone) to 6.25 and 25 mg/kg, respectively. Higher doses of BCNU alone or in combination with O6BG produced histopathologic evidence of cerebral and hepatic toxicity. Therapy experiments revealed a significantly improved median survival for rats treated with O6BG i.a. (2.5 mg/kg) plus BCNU i.v. (25 mg/kg, days 61 and 59 in duplicate experiments) compared with saline (day 21, P = 0.001), O6BG i.a. or i.p. (days 22 and 23, P = 0.001), BCNU i.v. (37.5 mg/kg, day 29, P = 0.001), and O6BG i.p. (10 mg/kg) plus BCNU i.v. (6.25 mg/kg, day 37, P < 0.001). Therefore, O6BG i.a., by virtue of rapid AGAT depletion and selective uptake into i.c. tumors, offers significant potential for regional chemomodulation of AGAT-mediated nitrosourea resistance in malignant human gliomas with concomitant reduction of systemic toxicity.

Original languageEnglish (US)
Pages (from-to)307-316
Number of pages10
JournalCancer Chemotherapy and Pharmacology
Volume39
Issue number4
DOIs
StatePublished - Jan 1 1997

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Nude Rats
Carmustine
Heterografts
Glioma
Rats
Therapeutics
Toxicity
Tumors
O(6)-benzylguanine
Chemotherapy
DNA alkyltransferase
Neoplasms
Repair
Experiments
Cells

All Science Journal Classification (ASJC) codes

  • Oncology
  • Toxicology
  • Pharmacology
  • Cancer Research
  • Pharmacology (medical)

Cite this

Kurpad, Shekar N. ; Dolan, M. Eileen ; McLendon, Roger E. ; Archer, Gerald E. ; Moschel, Robert C. ; Pegg, Anthony E. ; Bigner, Darell D. ; Friedman, Henry S. / Intraarterial O6-benzylguanine enables the specific therapy of nitrosourea resistant intracranial human glioma xenografts in athymic rats with 1,3-bis(2-chloroethyl)-1-nitrosourea. In: Cancer Chemotherapy and Pharmacology. 1997 ; Vol. 39, No. 4. pp. 307-316.
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abstract = "The prognosis for patients with malignant gliomas continues to be dismal. The high degree of resistance of gliomas to nitrosourea-based chemotherapy is one major factor in poor treatment outcome. The identification of O6-alkylguanine-DNA alkyltransferase (AGAT) as a major determinant of nitrosourea resistance has resulted in the development of several agents to inactivate this repair protein and counteract tumor cell resistance. However, a major problem in preclinical trials has been the marked nitrosourea dose limitations imposed by the prior administration of AGAT-depleting agents. We investigated the AGAT depletion and selective enhancement of BCNU activity of intraarterial (i.a.) O6-benzylguanine (O6BG) in the human malignant glioma xenograft D-456 MG growing intracranially (i.c.) in athymic rats. Whereas i.a. O6BG at 2.5 mg/kg produced 100{\%} inhibition of D-456 MG AGAT i.c. activity 8 h after administration, intraperitoneal (i.p.) O6BG at this dose produced only 40{\%} inhibition, requiring dose escalation to 10 mg/kg to produce 100{\%} AGAT depletion. Prior administration of i.p. O6BG (10 mg/kg) and i.a. O6BG (2.5 mg/kg) limited maximum tolerated intravenous (i.v.) BCNU doses (37.5 mg/kg when given alone) to 6.25 and 25 mg/kg, respectively. Higher doses of BCNU alone or in combination with O6BG produced histopathologic evidence of cerebral and hepatic toxicity. Therapy experiments revealed a significantly improved median survival for rats treated with O6BG i.a. (2.5 mg/kg) plus BCNU i.v. (25 mg/kg, days 61 and 59 in duplicate experiments) compared with saline (day 21, P = 0.001), O6BG i.a. or i.p. (days 22 and 23, P = 0.001), BCNU i.v. (37.5 mg/kg, day 29, P = 0.001), and O6BG i.p. (10 mg/kg) plus BCNU i.v. (6.25 mg/kg, day 37, P < 0.001). Therefore, O6BG i.a., by virtue of rapid AGAT depletion and selective uptake into i.c. tumors, offers significant potential for regional chemomodulation of AGAT-mediated nitrosourea resistance in malignant human gliomas with concomitant reduction of systemic toxicity.",
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Intraarterial O6-benzylguanine enables the specific therapy of nitrosourea resistant intracranial human glioma xenografts in athymic rats with 1,3-bis(2-chloroethyl)-1-nitrosourea. / Kurpad, Shekar N.; Dolan, M. Eileen; McLendon, Roger E.; Archer, Gerald E.; Moschel, Robert C.; Pegg, Anthony E.; Bigner, Darell D.; Friedman, Henry S.

In: Cancer Chemotherapy and Pharmacology, Vol. 39, No. 4, 01.01.1997, p. 307-316.

Research output: Contribution to journalArticle

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T1 - Intraarterial O6-benzylguanine enables the specific therapy of nitrosourea resistant intracranial human glioma xenografts in athymic rats with 1,3-bis(2-chloroethyl)-1-nitrosourea

AU - Kurpad, Shekar N.

AU - Dolan, M. Eileen

AU - McLendon, Roger E.

AU - Archer, Gerald E.

AU - Moschel, Robert C.

AU - Pegg, Anthony E.

AU - Bigner, Darell D.

AU - Friedman, Henry S.

PY - 1997/1/1

Y1 - 1997/1/1

N2 - The prognosis for patients with malignant gliomas continues to be dismal. The high degree of resistance of gliomas to nitrosourea-based chemotherapy is one major factor in poor treatment outcome. The identification of O6-alkylguanine-DNA alkyltransferase (AGAT) as a major determinant of nitrosourea resistance has resulted in the development of several agents to inactivate this repair protein and counteract tumor cell resistance. However, a major problem in preclinical trials has been the marked nitrosourea dose limitations imposed by the prior administration of AGAT-depleting agents. We investigated the AGAT depletion and selective enhancement of BCNU activity of intraarterial (i.a.) O6-benzylguanine (O6BG) in the human malignant glioma xenograft D-456 MG growing intracranially (i.c.) in athymic rats. Whereas i.a. O6BG at 2.5 mg/kg produced 100% inhibition of D-456 MG AGAT i.c. activity 8 h after administration, intraperitoneal (i.p.) O6BG at this dose produced only 40% inhibition, requiring dose escalation to 10 mg/kg to produce 100% AGAT depletion. Prior administration of i.p. O6BG (10 mg/kg) and i.a. O6BG (2.5 mg/kg) limited maximum tolerated intravenous (i.v.) BCNU doses (37.5 mg/kg when given alone) to 6.25 and 25 mg/kg, respectively. Higher doses of BCNU alone or in combination with O6BG produced histopathologic evidence of cerebral and hepatic toxicity. Therapy experiments revealed a significantly improved median survival for rats treated with O6BG i.a. (2.5 mg/kg) plus BCNU i.v. (25 mg/kg, days 61 and 59 in duplicate experiments) compared with saline (day 21, P = 0.001), O6BG i.a. or i.p. (days 22 and 23, P = 0.001), BCNU i.v. (37.5 mg/kg, day 29, P = 0.001), and O6BG i.p. (10 mg/kg) plus BCNU i.v. (6.25 mg/kg, day 37, P < 0.001). Therefore, O6BG i.a., by virtue of rapid AGAT depletion and selective uptake into i.c. tumors, offers significant potential for regional chemomodulation of AGAT-mediated nitrosourea resistance in malignant human gliomas with concomitant reduction of systemic toxicity.

AB - The prognosis for patients with malignant gliomas continues to be dismal. The high degree of resistance of gliomas to nitrosourea-based chemotherapy is one major factor in poor treatment outcome. The identification of O6-alkylguanine-DNA alkyltransferase (AGAT) as a major determinant of nitrosourea resistance has resulted in the development of several agents to inactivate this repair protein and counteract tumor cell resistance. However, a major problem in preclinical trials has been the marked nitrosourea dose limitations imposed by the prior administration of AGAT-depleting agents. We investigated the AGAT depletion and selective enhancement of BCNU activity of intraarterial (i.a.) O6-benzylguanine (O6BG) in the human malignant glioma xenograft D-456 MG growing intracranially (i.c.) in athymic rats. Whereas i.a. O6BG at 2.5 mg/kg produced 100% inhibition of D-456 MG AGAT i.c. activity 8 h after administration, intraperitoneal (i.p.) O6BG at this dose produced only 40% inhibition, requiring dose escalation to 10 mg/kg to produce 100% AGAT depletion. Prior administration of i.p. O6BG (10 mg/kg) and i.a. O6BG (2.5 mg/kg) limited maximum tolerated intravenous (i.v.) BCNU doses (37.5 mg/kg when given alone) to 6.25 and 25 mg/kg, respectively. Higher doses of BCNU alone or in combination with O6BG produced histopathologic evidence of cerebral and hepatic toxicity. Therapy experiments revealed a significantly improved median survival for rats treated with O6BG i.a. (2.5 mg/kg) plus BCNU i.v. (25 mg/kg, days 61 and 59 in duplicate experiments) compared with saline (day 21, P = 0.001), O6BG i.a. or i.p. (days 22 and 23, P = 0.001), BCNU i.v. (37.5 mg/kg, day 29, P = 0.001), and O6BG i.p. (10 mg/kg) plus BCNU i.v. (6.25 mg/kg, day 37, P < 0.001). Therefore, O6BG i.a., by virtue of rapid AGAT depletion and selective uptake into i.c. tumors, offers significant potential for regional chemomodulation of AGAT-mediated nitrosourea resistance in malignant human gliomas with concomitant reduction of systemic toxicity.

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