Glioblastoma is a devastating cerebral tumour with a median survival time of 10-12 months. Current treatment involves surgical resection of the tumour, followed by chemotherapy and/or radiotherapy. Recent work in our laboratory has characterised the accumulation and retention of nanomedicines within brain tumours, following progressive leakiness of the blood brain barrier (BBB). A major challenge is to not only deliver high amounts of these nanomedicines into the tumour, but also into the extremities of the complex heterogeneous environment. This work further evaluated the delivery of doxorubicin-loaded PEG-based hyperbranched polymers into murine glioma at an optimal time-window. The polymers were synthesised using established RAFT-based strategies and targeted to Ephrin receptors unregulated on the tumours using a bispecific antibody approach previously reported by our group. A treatment regime of five equal biweekly injections was then tested, and the effect of treatment was monitored in real time using MRI and PET scanning. Overall, this research provides insight into the advantages of using hyperbranched polymers, and EphA2-targeting with bispecific antibodies, for intracellular-localised and safer chemotherapy of glioblastoma.