Nanoparticle encapsulation enables systemic IGF-Trap delivery to inhibit intra-cerebral glioma growth

Abstract 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.