Indium-111-labelled liposomes: dosimetry and tumour detection in patients with cancer

Neutral phospholipid vesicles (VesCan), which had been prepared for clinical use, were loaded with 37 MBq indium-111 and administered to seven patients with malignant tumours. The median lipid dose was 2.0 mg/kg. Sequential images showed rapid blood clearance at the early stage, with homogeneous uptake of 111In-labelled VesCan (111In-labelled V-liposomes) in the liver and spleen. Dosimetric estimates for these organs were 1.2 and 1.5 mGy/MBq, respectively, with a whole-body exposure dose of 0.076 mGy/MBq. Total renal excretion of 111In was less than 10% of the injected dose, occurring mainly as 111In-EDTA in three patients. Gamma camera images 24-48 h after administration revealed increased activity in the tumours of four patients. 111In-labelled V-liposomes may enable the demonstration of the tumour site without toxicity and with radiation doses comparable to other radionuclide imaging techniques.