Glioblastomas belong to the most aggressive human cancers with short survival times.Due to the blood-brainbarrier,they are mostly inaccessible to traditional chemotherapy.We have recently shown that doxorubicin boundto polysorbate-coated nanoparticles crossed the intact blood-brain barrier,thus reaching therapeutic concentra-tions in the brain.Here,we investigated the therapeutic potential of this formulation of doxorubicin in vivo using ananimal model created by implantation of 101/8 glioblastoma tumor in rat brains.Groups of 5-8 glioblastoma- Glioblastomas belong to the most aggressive human cancers with short survival times. Due to the blood-brain barrier, they are mostly inaccessible to traditional chemotherapy. We have recently demonstrated that doxorubicin bound to polysorbate-coated nanoparticles crossed the intact blood-brain barrier, thus reaching therapeutic concentra-tions in the brain. Here, we investigated the therapeutic potential of this formulation of doxorubicin in vivo using an animal model created by implantation of 101/8 glioblastoma tumor in rat brains. Group of 5-8 glioblastoma-