Nanoparticle encapsulation enables systemic IGF-Trap delivery to inhibit intracerebral glioma growth.

BACKGROUND: Glioblastoma is an aggressive brain cancer with a 5-year survival rate of 5-10%. Current therapeutic options are limited, due in part to drug exclusion by the blood-brain barrier, restricting access of targeted drugs to the tumor. The receptor for the type 1 insulin-like growth factor (IGF-1R) was identified as a therapeutic target in glioblastoma. We previously reported that the intracerebral growth of glioma cells with reduced IGF-1R levels was inhibited. The objectives of this study were to evaluate the sensitivity of glioma cells to a novel IGF-axis inhibitor, the IGF-Trap, and optimize its delivery to the brain. METHODS: We tested the effect of the IGF-Trap on the growth of the human glioma stem cells MES-1123 and U87 MG cells, and of murine GL261 cells in vivo, using subcutaneous and orthotopic implantation. RESULTS: We show that the growth of glioma cells implanted subcutaneously or orthotopically in the brain was inhibited by systemic and direct intracerebral administration of IGF-Trap, respectively, resulting in increased survival. To increase the efficiency of systemic delivery to the brain, we encapsulated the IGF-Trap in trimethyl chitosan (TRIOZAN™) nanoparticles prior to intravenous injection. We found that nanoparticle encapsulation increased the uptake and retention of the IGF-Trap in the brain and resulted in an improved therapeutic effect against intra-cerebrally growing tumors. CONCLUSION: Our results identify the IGF-Trap as a potent inhibitor of intracerebral glioma growth and show that encapsulation in nanoparticles can improve delivery of biologics such as the IGF-Trap to the brain, thereby enhancing the therapeutic response.