Scheme 6.

Active targeting to tumors by integrin-binding peptides combines the effects deriving from the peptides and a carrier nanoparticle. Integrin-binding peptides show various effects on cancer cells and tumors: from inhibition of tumor progression and metastasis to the opposite effect, and in some cases no effect on cancer cell proliferation or cytotoxicity are observed. If administered in a non-targeted way, nanoparticles retain in tumors due to the EPR effect, or passive targeting. Combined together, these active targeted nanoparticles retain in tumors due to both active and passive targeting, and are proposed for tumor and metastases visualization and eradication of thereof due to cytotoxicity, necrosis, or apoptosis.