One of the major obstacles to the effective treatment of cancer patients with potent anti-cancer medications is the successful delivery of the drug(s) to the entire tumor mass. Investigators led by Dr. Kazuki N. Sugahara at the Vascular Mapping Laboratory at the Center for Nanomedicine, Stanford-Burnham Medical Research Institute at the University of California at Santa Barbara have devised an approach to overcome this limitation.
Using the mouse as the animal model, they have utilized a tumor-penetrating peptide (a small protein) called iRGD to effectively increase the access of anti-cancer drugs to cancerous tumors and, thereby, increase the therapeutic potency of these medications.
The peptide iRGD penetrates into an actively proliferating tumor mass by specifically binding to the av integrins – proteins that are uniquely found on the endothelium (the cells that line the interior wall of blood vessels) of tumor blood vessels. In fact, when iRGD was co-injected with an albumin – albumin is a common protein found in circulating blood - binding dye used as a marker, the dye was found to successfully accumulate in five different tumor models including breast, prostate and pancreatic cancers.
In addition, the scientists involved in this research found that iRGD when co-injected with the anti-cancer drug Doxorubicin (DOX) resulted in a sevenfold increase in accumulation of DOX in prostate cancer tumors in the animals studies.
These results are especially encouraging given the fact that many anti-cancer drugs like DOX have significant side effects at high doses. This serious limitation can be sidestepped if the drug gains access to tumor cells at more manageable doses.