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Posted: February 12, 2007
Nanoparticle boost for antitumor vaccines
(Nanowerk News) Researchers have known for some time that certain sequences of synthetic DNA induce potent immune responses when injected into animals and humans. A new study, conducted by Ying Tam, Ph.D., and colleagues at Inex Pharmaceuticals, demonstrates that encapsulating these synthetic DNAs in lipid-based nanoparticles greatly enhances the immunogenicity of these DNAs and that the nanoparticle-encased DNA sequences trigger antitumor activity when administered together with tumor-associated antigens.
Previous work by this group of investigators showed that lipid-based nanoparticles enhance the immune system stimulation activity of so-called CpG oligodeoxynucleotides by improving their uptake by immune cells. This boost occurs regardless of whether the nanoparticles are injected into the bloodstream, beneath the skin (subcutaneously), or directly into a tumor.
In the current study, the results of which were published in the journal Cancer Immunology and Immunotherapy ("Encapsulation in liposomal nanoparticles enhances the immunostimulatory, adjuvant and anti-tumor activity of subcutaneously administered CpG ODN."), the investigators wanted to determine if the nanoparticle-encapsulated CpG construct could be used to create antitumor vaccines from tumor-associated antigens. To test this hypothesis, the researchers co-injected the nanoparticles and an antigen known as TRP-2, which is found on melanoma cells, into a mouse model of melanoma. Animals injected with TRP-2 or empty nanoparticles showed no antitumor response. In contrast, mice injected with CpG-containing nanoparticles and TRP-2 showed a large, statistically signficant decrease in the number of lung metastases.