Targeted drug delivery using iRGD peptide for solid cancer treatment

Many solid tumor types, such as pancreatic cancer, have a generally poor prognosis, in part because the delivery of a therapeutic regimen is prohibited by pathological abnormalities that block access to tumor vasculature, leading to poor bioavailability. The recent development of the tumor-penetrating iRGD peptide that is covalently conjugated on the nanocarriers' surface or co-administered with nanocarriers becomes a popular approach for tumor targeting. More importantly, scientists have unlocked an important tumor transcytosis mechanism by which drug-carrying nanoparticles directly access solid tumors (that seems to be independent to leaky vasculature), thereby allowing systemically injected nanocarriers to more abundantly distribute at the tumor site with improved efficacy. In this focused review, we summarize the design and implementation strategy for iRGD-mediated tumor targeting. This includes the working principle of such a peptide and discussion on a patient-specific iRGD effect in vivo, commensurate with the level of key biomarker (i.e. neuropilin-1) expression in tumor vasculature. This highlights the necessity to contemplate the use of a personalized approach when iRGD technology is used in the clinic.