Polyacetal−Doxorubicin Conjugates Designed for pH-Dependent Degradation

Tomlinson, R., Heller, J., Brocchini, S. and Duncan, R. (2003) Polyacetal−Doxorubicin Conjugates Designed for pH-Dependent Degradation. Bioconjugate Chemistry, 14 (6). pp. 1096-1106. 10.1021/bc030028a.

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DOI: 10.1021/bc030028a

Abstract

Terpolymerization of poly(ethylene glycol) (PEG), divinyl ethers, and serinol can be used to synthesize water soluble, hydrolytically labile, amino-pendent polyacetals (APEGs) suitable for drug conjugation. As these polyacetals display pH-dependent degradation (with faster rates of hydrolysis at acidic pH) and they are not inherently hepatotropic after intravenous (iv) injection, they have potential for development as biodegradable carriers to facilitate improved tumor targeting of anticancer agents. The aim of this study was to synthesize a polyacetal-doxorubicin (APEG-DOX) conjugate, determine its cytotoxicity in vitro and evaluate its potential for improved tumor targeting in vivo compared to an HPMA copolymer-DOX conjugate in clinical development. Amino-pendent polyacetals were prepared, and following succinoylation (APEG-succ), the polymeric intermediate conjugated to DOX via one of three methods using carbodiimide mediated coupling (1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) in aqueous solution was the most successful). The resultant APEG-DOX conjugates had a DOX content of 3.0-8.5 wt %, contained <1.2% free DOX (relative to total DOX content) and had a MW = 60000-100000 g/mol and MW/Mn = 1.7-2.6. In vitro cytotoxicity studies showed APEG-DOX to be 10-fold less toxic toward B16F10 cells than free DOX (IC50 = 6μg/mL and 0.6 μg/mL respectively), but confirmed the serinol-succinoyl-DOX liberated during main-chain degradation to be biologically active. When administered iv to C57 black mice bearing subcutaneous (sc) B16F10 melanoma, APEG-DOX of MW = 86000 g/mol, and 5.0 wt % DOX content exhibited significantly (p < 0.05) prolonged blood half-life and enhanced tumor accumulation compared to an HPMA copolymer-GFLG-DOX conjugate of MW = 30000 g/mol and 6.2 wt % DOX content. Moreover, APEG-DOX exhibited lower uptake by liver and spleen. These observations suggest that APEG anticancer conjugates warrant further development as novel polymer therapeutics for improved tumor targeting.

Item Type:Article
Departments, units and centres:Department of Pharmaceutics > Department of Pharmaceutics
ID Code:2863
Journal or Publication Title:Bioconjugate Chemistry
Deposited By:Library Staff
Deposited On:24 Feb 2012 16:19
Last Modified:24 Feb 2012 16:19

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