Doxorubicin is one of the most effective substances in vitro against cells derived from glioblastoma. However, it has no significant effect in vivo due to poor blood-brain-barrier penetration. In a tumor model, tissue and CSF-concentrations of doxorubicin were substantially increased when sterically stabilized liposomes were used resulting in a comparable clinical response using approximately half of the dose of stabilized liposomes compared to conventional doxorubicin. A pegylated formulation (PEG-liposomal Doxorubicin) even further improved the penetration of the blood-brain barrier. Case series and two phase II-studies in patients with recurrent glioblastoma have shown modestly promising results for PEG-Dox.