Polyacetal-diethylstilboestrol: a polymeric drug designed for pH-triggered activation

Area of Science:

• Polymer Chemistry
• Medicinal Chemistry
• Materials Science

Background:

• Current polymer anticancer-drug conjugates have a tripartite structure (polymer, drug, linker).
• Simplifying this construct by integrating the drug into the polymer backbone is desirable for improved therapeutic strategies.

Purpose of the Study:

• To synthesize polyacetals incorporating a bis-hydroxyl functional drug into the polymer backbone.
• To develop anticancer polymer therapeutics with main-chain drug incorporation for triggered release.

Main Methods:

• Utilized a tert-polymerization reaction between divinyl ethers and diols (PEG) to incorporate diethylstilbestrol (DES).
• Characterized the resulting polymers using GPC and 1H-NMR spectroscopy.
• Evaluated in vitro cytotoxicity against MCF-7 and B16F10 cancer cell lines.
• Assessed hydrolytic degradation and drug release at different pH values.

Main Results:

• Synthesized water-soluble polyacetals with DES incorporated into the main chain, achieving DES loadings of 4.3-4.7 wt.%.
• DES-polyacetals exhibited significantly greater cytotoxicity than free DES against human and murine tumor cell lines.
• Polymers demonstrated minimal hemolysis up to 20 mg/ml, indicating good hemocompatibility.
• Enhanced hydrolytic degradation and release of DES at acidic pH (5.5) compared to neutral pH (7.4).

Conclusions:

• Developed the first water-soluble anticancer polymers with main-chain drug incorporation for acidic pH-triggered release.
• These bioresponsive DES-polyacetals offer a simplified construct and enhanced therapeutic potential.
• The promising in vitro characteristics warrant further in vivo evaluation for anticancer applications.