Biodegradable hybrid polymer micelles for combination drug therapy in ovarian cancer

Abstract

The co-delivery of drug combination at a controlled ratio via the same vehicle to the cancer cells is offering the advantages such as spatial–temporal synchronization of drug exposure, synergistic therapeutic effects and increased therapeutic potency. In an attempt to develop such multidrug vehicle this work focuses on functional biodegradable and biocompatible polypeptide-based polymeric micelles. Triblock copolymers containing the blocks of ethylene glycol, glutamic acid and phenylalanine (PEG–PGlu–PPhe) were successfully synthesized via NCA-based ring-opening copolymerization and their composition was confirmed by 1H NMR. Self-assembly behavior of PEG–PGlu90–PPhe25 was utilized for the synthesis of hybrid micelles with PPhe hydrophobic core, cross-linked ionic PGlu intermediate shell layer, and PEG corona. Cross-linked (cl) micelles were about 90nm in diameter (ξ-potential=−20mV), uniform (narrow size distribution), and exhibited nanogels-like behavior. Degradation of cl-micelles was observed in the presence of proteolytic enzymes (cathepsin B). The resulting cl-micelles can incorporate the combination of drugs with very different physical properties such as cisplatin (15 w/w% loading) and paclitaxel (9 w/w% loading). Binary drug combination in cl-micelles exhibited synergistic cytotoxicity against human ovarian A2780 cancer cells and exerted a superior antitumor activity by comparison to individual drug-loaded micelles or free cisplatin in cancer xenograft model in vivo. Tunable composition and stability of these hybrid biodegradable micelles provide platform for drug combination delivery in a broad range of cancers.