Enhanced permeability and retention effect in tumor tissue (EPR effect)

The enhanced permeability and retention (EPR) effect is a property of solid tumor tissue characterized by abnormal, leaky vasculature and poor lymphatic drainage[1][2][3][4][5][6][7]. These features allow macromolecules, such as nanoparticles, liposomes, and polymer-conjugated drugs, to accumulate and be retained in tumor tissue at greater levels than in normal tissues. The EPR effect is foundational for passive tumor targeting in nanomedicine, but its efficacy in humans is limited and varies greatly between tumor types and patients[4][6][7]. The EPR mechanism is not a druggable receptor, enzyme, transporter, or other canonical molecular target; rather, it is a widely used concept to guide the design of tumor-targeted drug delivery systems[1][2][3][4][5]. Note: For databases and structured informatics, this entry should not be indexed as a molecule or receptor target, but as a tissue-level pathophysiological property whose exploitation is critical for nanoparticle-based tumor therapies.

Other names

EPR effectEnhanced permeability and retention phenomenonPassive tumor targeting

Passive targeting and accumulation of drugs via leaky tumor vasculature and impaired lymphatic drainage. Drugs are carried into tumor by nanoparticles exploiting the EPR effect, allowing for enhanced retention and drug release within the tumor microenvironment.