Synthesis and Structure-Activity Relationships for 2,4-Dinitrobenzamide-5-mustards as Prodrugs for the Escherichia coli nfsB Nitroreductase in Gene Therapy

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• 作者：Graham J. Atwell ; Shangjin Yang ; Frederik B. Pruijn ; Susan M. Pullen ; Alison Hogg ; Adam V. Patterson ; William R. Wilson ; William A. Denny
• 刊名：Journal of Medicinal Chemistry
• 出版年：2007
• 出版时间：March 22, 2007
• 年：2007
• 卷：50
• 期：6
• 页码：1197 - 1212
• 全文大小：281K
• 年卷期：v.50,no.6(March 22, 2007)
• ISSN：1520-4804

文摘

A series of 2,4-dinitrobenzamide mustards were prepared from 5-chloro-2,4-dinitrobenzoic acid or thecorresponding 5-dimesylate mustard as potential prodrugs for gene-directed enzyme prodrug therapy (GDEPT)with the E. coli nfsB nitroreductase (NTR). The compounds, including 32 new examples, were evaluated infour pairs of NTR^+ve/-ve cell lines for selective cytotoxicity (IC₅₀ and IC₅₀ ratios), in multicellular layer(MCL) cultures for bystander effects, and for in vivo activity against tumors grown from stably NTRtransfected EMT6 and WiDr cells in nude mice. Multivariate regression analysis of the IC₅₀ results wasundertaken using a partial least-squares projection to latent structures model. In NTR^-ve lines, cytotoxicitycorrelated positively with logP, negatively with hydrogen bond acceptors (HA) and donors (HD) in theamide side chain, and positively with the reactivity of the less-reactive leaving group of the mustard function,likely reflecting toxicity due to DNA monoadducts. Potency and selectivity for NTR^+ve lines was increasedby logP and HD, decreased by HA, and was positively correlated with the leaving group efficiency of themore-reactive group, likely reflecting DNA crosslinking. NTR selectivity was greatest for asymmetric chloro/mesylate and bromo/mesylate mustards. Bystander effects in the MCL assay also correlated positively withlogP and negatively with leaving group reactivity, presumably reflecting the transcellular diffusion/reactionproperties of the activated metabolites. A total of 18 of 22 mustards showed equal or greater bystanderefficiencies in MCLs than the aziridinylbenzamide CB 1954, which is currently in clinical trial for NTR-GDEPT. The dibromo and bromomesylate mustards were surprisingly well tolerated in mice. High MTD/IC₅₀ (NTR^+ve) ratios translated into curative activity of several compounds against NTR^+ve tumors. Abromomesylate mustard showed superior activity against WiDr tumors grown from 1:9 mixtures of NTR^+veand NTR^-ve cells, indicating a strong bystander effect in vivo.