Liposomal distribution in malignant glioma: possibilities for therapy

We investigated the potential of 111In-labelled liposomes to specifically target recurrent high-grade glioma in eight patients, all of whom had clinical and radiological evidence of relapse following prior treatment with surgery and radiotherapy. The phospholipid liposomes were labelled with 74 MBq 111In and injected intravenously. The distribution of radioactive material in the brain was imaged using a dedicated neuro-SPET imager. Images were taken 1 h post-injection and repeated at 24, 48 and 72 h. In addition, whole-body images were performed with a gamma camera and blood taken for radioactivity determination. At 72 h post-injection, excellent tumour demarcation could be seen in seven of eight patients. The images obtained correlated well with the corresponding computed tomography images. Blood radioactivity levels gradually declined over the 72 h. Tumour uptake continued to rise throughout this time and, together with the steady fall in normal brain tissue, the tumour-to-brain contrast gradually increased (maximum 7:5). Whole-body images indicate that the liver is the major organ of uptake with up to 50% of the injected dose. No toxicity could be attributed to the injected liposomes. Although the total percentage uptake was low (1.1%), the tumour-to-brain contrast ratios, together with the SPET images, suggest the potential for tumour-specific targeting.