Abstract | PURPOSE: A major mechanism of resistance to chlorethylnitrosureas and methylating agents involves the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT). We sought to determine the dose of oral 6-(4-bromo-2-thienyl) methoxy purin-2-amine ( lomeguatrib), a pseudosubstrate inactivator of MGMT, required to render active protein undetectable 12 hours after dosing in prostate, primary central nervous system (CNS), and colorectal cancer patients. EXPERIMENTAL DESIGN:
Lomeguatrib was administered orally as a single dose (20-160 mg) approximately 12 hours before tumor resection. Dose escalation was projected to continue until grade 2 toxicity or until complete inactivation of tumor MGMT was encountered. Total MGMT protein levels were quantified by ELISA, and active protein levels were quantified by biochemical assay. MGMT promoter methylation was determined in glioblastoma DNA by methylation-specific PCR. RESULTS: CONCLUSIONS: Total MGMT inactivation can be achieved in prostate, primary CNS, and colorectal cancers with a single administration of 120 or 160 mg lomeguatrib. The dose needed did not correlate with mean total MGMT protein concentrations. One hundred twenty to 160 mg/d of lomeguatrib should be administered to achieve total MGMT inactivation in future studies.
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Authors | Amanda J Watson, Ami Sabharwal, Mary Thorncroft, Gail McGown, Richard Kerr, Stana Bojanic, Zahir Soonawalla, Alexandra King, Andrea Miller, Sue Waller, Hing Leung, Geoffrey P Margison, Mark R Middleton |
Journal | Clinical cancer research : an official journal of the American Association for Cancer Research
(Clin Cancer Res)
Vol. 16
Issue 2
Pg. 743-9
(Jan 15 2010)
ISSN: 1557-3265 [Electronic] United States |
PMID | 20068091
(Publication Type: Clinical Trial, Journal Article, Multicenter Study, Research Support, Non-U.S. Gov't)
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Chemical References |
- Antineoplastic Agents
- Biomarkers, Pharmacological
- Purines
- O(6)-Methylguanine-DNA Methyltransferase
- lomeguatrib
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Topics |
- Administration, Oral
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Antineoplastic Agents
(administration & dosage, adverse effects, pharmacology)
- Biomarkers, Pharmacological
(analysis)
- Combined Modality Therapy
- DNA Methylation
(drug effects)
- Dose-Response Relationship, Drug
- Female
- Gene Expression Regulation, Enzymologic
(drug effects)
- Gene Expression Regulation, Neoplastic
(drug effects)
- Gene Silencing
(drug effects)
- Humans
- Male
- Middle Aged
- Neoplasms
(drug therapy, genetics, pathology, surgery)
- O(6)-Methylguanine-DNA Methyltransferase
(genetics, metabolism)
- Purines
(administration & dosage, adverse effects, pharmacology)
- Young Adult
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