Bio-distribution and anti-tumor efficacy of PEG/PLA nano particles loaded doxorubicin

As a more effective in vivo drug delivery system, several methods loading anti- cancer drugs to biodegeradable and biocompatible nano-particles have been explored and developed. Supposedly due to the enhanced permeability and retention ( EPR) effect, systemic administration of these nano-particles have been found to result in accumulation of nano- particles into solid tumors. In this study, we prepared nano- particles using polyethylene glycol ( PEG)/poly-L-lactide ( PLLA) diblock copolymer and loaded doxorubicin into these nano- particles ( Nano-dox). The fabricated nano- particles exhibited sustained release kinetics of the drug in vitro. To follow the in vivo biodistribution of 200 - 350nm sized nano-dox particles in tumor ( syngenic renal cell adenocarcinoma: RENCA) bearing mouse, the carboxylfluorescenin diacetate succinimidyl ester ( CFSE) was loaded into the nano-particles. Nano-dox accumulated preferentially in tumors; however, in terms of its anti- tumor efficacy, it did not show any marked benefits, compared to freely- administered doxorubicin. This result suggests the need to re- consider and evalute what type of anti-cancer reagents we to be used in the ongoing efforts of coupling drug delivery system with tumor EPR effects.