Application of boron-entrapped stealth liposomes to inhibition of growth of tumour cells in the in vivo boron neutron-capture therapy model

Abstract Tumour cell destruction in boron neutron-capture therapy (BNCT) is due to the nuclear reaction between 10 B and thermal neutrons. It is necessary for effective BNCT therapy to accumulate 10 B atoms in the tumour cells. The delivery system consisted of polyethylene-glycol (PEG) binding liposomes (DPPC/cholesterol/DSPC-PEG2000) with an entrapped 10 B-compound and we evaluated the cytotoxic effects of intravenously injected 10 B-PEG-liposomes on human pancreatic carcinoma xenografts in nude mice with thermal neutron irradiation. After thermal neutron irradiation of mice injected with 10 B-PEG-liposomes, growth of AsPC-1 tumours was suppressed relative to controls. Injection of 10 B-PEG-liposomes caused the greatest tumour suppression with thermal neutron irradiation in vivo. These results suggest that intravenous injection of 10 B-PEG-liposomes can increase the retention of 10 B atoms by tumour cells, causing suppression of tumour growth in vivo, after thermal neutron irradiation.