Figure 6.

Suggested pathways for development of a nanomedicine by the pharmaceutical industry. Bypassing rather than exploiting the EPR effect may achieve better tumor control.

Notes: (A) Two pathways for the development of nanomedicine. The classical pathway refers to exploiting the EPR effect, whereas the alternative pathway refers to bypassing the EPR effect. Different points can be used to optimize nanoparticles for each pathway. (B) Regional delivery of nanomedicine. At the two extremes (conjugates that are too loose or too tight), a nanomedicine may produce unsatisfactory tumor-killing effects. Conjugates that are too loose behave as a free drug that produces a moderate effect, whereas conjugates that are too tight have almost no effect. Only regional delivery of a sustained-release nanomedicine in a timely fashion can produce satisfactory tumor-killing effects.

Abbreviations: CNS, central nervous system; EPR, enhanced permeability and retention; RES, reticuloendothelial system.