Alpha-helical, Hydrolysis-mediated Polymer-drug Conjugates derived from Poly(propargyl-L-glutamate)

Presenter: 

Brian Zhong

Authors: 

Brian Zhong Wade Wang Paula T. Hammond

Author Affiliation: 

B. Zhong: MIT Department of Chemical Engineering W. Wang: MIT Department of Chemistry P. T. Hammond: MIT Department of Chemical Engineering

Abstract: 

Cancer drugs are often small molecules that are effective at inhibiting cell growth, but suffer from low circulation time in the body due to rapid clearance by the kidneys. Polymer-drug conjugates mitigate this drawback by covalently binding the drug to polymers to reduce clearance. We have synthesized polymer-drug conjugates derived from an alpha-helical, poly(propargyl-L-glutamate) (PPLG) backbone using doxorubicin (Dox) as a model cancer drug. PPLG was synthesized via N-carboxyanhydride ring-opening polymerization of propargyl-L-glutamate. Dox was covalently bound to an azide-functionalized linker through an acid-labile hydrazone bond. Azide-functionalized Dox was attached to PPLG using copper-mediated azide-alkyne cycloaddition, and poly(ethylene glycol) (PEG) and dextran were attached as solubilizing fillers to yield polymer-drug conjugates with drug content of up to 34 wt%. Release profiles of the conjugates were obtained in PBS and cytotoxicity of the conjugates was evaluated in vitro. The conjugates released up to 65% of the drug content over 120 hours in PBS at pH 4 compared to 22% at pH 7.4. The IC50 values for the conjugates were found to be 10-100 times higher than those of free Dox. These results suggest that PPLG polymer-drug conjugates are viable drug-delivery vehicles for small molecule cancer drugs.