Enhanced permeability and retention effect for selective targeting of anticancer nanomedicine: are we there yet?

Enhanced permeability and retention (EPR) effect is a popular strategy for targeting nanosize anticancer drugs to tumor tissues. In this review we discuss how EPR effect outcome can be influenced by variables such as tumor diversity, animal models, biodistribution, intracellular interaction, and release rate of active cytotoxic cargo from its nanosize carrier. Thoughtful understanding of the phenomenon and its limitation is crucial for the clinical success of EPR-based anticancer nanomedicine.