Synthesis of a macromolecular camptothecin conjugate with dual phase drug release

Mol Pharm. Sep-Oct 2004;1(5):375-82. doi: 10.1021/mp0499306.

Abstract

A water soluble macromolecular conjugate of camptothecin (CPT) with a new, dual phase hydrolytic drug release mechanism was prepared on the basis of a 60 kDa biodegradable hydrophilic "stealth" polyacetal, poly(1-hydroxymethylethylene hydroxy-methyl formal). Succinamido-glycinate was used as a prodrug releasing group. A model preparation with 7.5% CPT content w/w was water soluble. The lipophilic camptothecin prodrug, camptothecin-(O20)-succinimidoglycinate, was released from the conjugate with t(1/2) = 2.2 +/- 0.1 h in rodent plasma. The blood clearance in a rodent model as measured by CPT was release limited, t(1/2) = 2.1 +/- 0.2 h, while the conjugate half-life was 14.2 +/- 1.7 h. In a xenograft tumor model, the conjugate demonstrated higher antineoplastic efficacy than CPT at a less than equitoxic dose. This improved therapeutic window is in line with the modified drug pharmacokinetics and with camptothecin release in a stabilized lipophilic prodrug form. Regulation of prodrug release and hydrolysis rates through linker structure modification will open the way to further improve both pharmacokinetics and pharmacodynamics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenocarcinoma / drug therapy*
  • Adenocarcinoma / metabolism
  • Animals
  • Antineoplastic Agents / chemical synthesis*
  • Antineoplastic Agents / therapeutic use
  • Camptothecin / analogs & derivatives
  • Camptothecin / chemical synthesis*
  • Camptothecin / therapeutic use
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Colonic Neoplasms / drug therapy*
  • Colonic Neoplasms / metabolism
  • Delayed-Action Preparations / chemical synthesis
  • Delayed-Action Preparations / therapeutic use
  • Drug Stability
  • Glycine / analogs & derivatives
  • Glycine / chemical synthesis*
  • Glycine / therapeutic use
  • Humans
  • Macromolecular Substances / chemical synthesis
  • Macromolecular Substances / therapeutic use
  • Male
  • Mice
  • Mice, Nude
  • Molecular Structure
  • Time Factors
  • Xenograft Model Antitumor Assays / methods

Substances

  • Antineoplastic Agents
  • Delayed-Action Preparations
  • Macromolecular Substances
  • Glycine
  • Camptothecin