This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ward, T. H. Articles by Butler, J. Search for Related Content PubMed PubMed Citation Articles by Ward, T. H. Articles by Butler, J.

Preclinical Evaluation of the Pharmacodynamic Properties of 2,5-Diaziridinyl-3-Hydroxymethyl-6-Methyl-1,4-Benzoquinone

Authors' Affiliations: ¹ Clinical and Experimental Pharmacology Group, Paterson Institute for Cancer Research, Christie Hospital; ² Department of Oncology, Christie Hospital, Manchester; and ³ Drug Design Group, University of Salford, Salford, United Kingdom

Requests for reprints: Timothy H. Ward, Clinical and Experimental Pharmacology group, Paterson Institute for Cancer Research, Christie Hospital NHS Trust,Wilmslow Road, Manchester M20 4BX, United Kingdom. Phone:44-0-161-446-3149; Fax: 44-0-161-446-3109; E-mail: tward{at}picr.man.ac.uk.

Purpose: The purpose of our study was to investigate the cellular accumulation, DNA cross-linking ability, and cellular toxicity of RH1 (2,5-diaziridinyl-3-[hydroxymethyl[-6-methyl-1,4-benzoquinone), a novel DNA alkylating agent currently in clinical trials. In addition, the in vivo efficacy of RH1 formulated in different vehicles was also compared.

Experimental Design: RH1 is activated by the two-electron reducing enzyme NQO1 [NAD(P)H:quinone oxidoreductase] forming a potent cytotoxic agent that cross-links DNA. We have used whole blood, cell lines, and primary explanted tumor cultures to measure both the cellular accumulation, DNA cross-linking, and cytotoxicity of RH1. Furthermore, the pharmacokinetic and pharmacodynamic characteristics of RH1 formulated in different vehicles were measured in vivo using the validated comet-X assay in mice bearing human tumor xenografts.

Results: Accumulation of RH1 was shown to be both time and concentration dependent, reaching a maximum after 2 hours and correlated well with DNA cross-linking measurements. DNA cross-linking in vitro could be detected at low (1-10 nmol/L) concentrations after as little as 2 hours exposure. In primary tumor cultures, RH1 induces much higher levels of DNA cross-links at lower doses than either mitomycin C or cisplatin. In vivo efficacy testing using polyvinyl pyrrolidone, saline, or cyclodextrin as vehicles showed DNA cross-links readily detectable in all tissues examined and was enhanced when given in cyclodextrin compared with polyvinyl pyrrolidone or saline.

Conclusions: RH1 represents a potent bioreductive anticancer drug, which may prove effective in the treatment of cancers, particularly those that overexpress NQO1. DNA cross-linking can be reliably measured in tissue using the validated comet-X assay.

Key Words: Comet-assay • DNA Cross-linking • pharmacokinetics • bioreductive activation