Santa Barbara, Calif., April 8, 2010 Researchers have shown that a peptide (a chain of amino acids) called iRGD helps co-administered drugs penetrate deeply into tumor tissue. The peptide has been shown to substantially increase treatment efficacy against human breast, prostate and pancreatic cancers in mice, achieving the same therapeutic effect as a normal dose with one-third as much of the drug. In a transformative paper published today in the online edition of the journal Science, Erkki Ruoslahti, M.D., Ph.D., distinguished professor at Sanford-Burnham Medical Research Institute and founding member of the UC Santa Barbara-Sanford|Burnham Center for Nanomedicine, Kazuki N. Sugahara, M.D., Ph.D., Tambet Teesalu, Ph.D., and fellow researchers at the Center for Nanomedicine and the Cancer Center of Santa Barbara, announced this significant advance in cancer therapy.
"Drugs generally have difficulty penetrating tumors beyond a few cell diameters from a blood vessel," said Dr. Ruoslahti. "This leaves some tumor cells with a suboptimal dose, increasing the risk of both recurrence and drug resistance. The iRGD peptide solves this problem by activating a transport system in tumors that distributes co-injected drugs into the entire tumor and increases drug accumulation in the tumor."
Dr. Ruoslahti showed in the 1980s that a 3 amino-acid peptide motif (RGDArginine-Glycine-Aspartic Acid) serves as a highly selective identifier of malignant tissue, binding to unique re-ceptors in the vasculature of cancers. The RGD peptide's ability to home to tumors has been used to design new compounds for cancer diagnosis and treatment.
The new variant of RGD (iRGDinternalizing RGD) combines the RGD motif with a tissue penetration element called CendR. Like the earlier RGD peptides, iRGD homes to tumors, but exposure of the CendR motif when the iRGD is enzymatically cleaved activates a transport system through tumor blood vessel walls into the tum
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Sanford-Burnham Medical Research Institute