Selective boron accumulation in human ocular melanoma vs surrounding eye components after 10B1-p-boronophenylalanine administration. Prerequisite for clinical trial of neutron-capture therapy.

We have developed neutron-capture therapy (NCT) for cutaneous malignant melanoma using a melanoma-seeking 10B-dopa, analogue, 10B1-para-boronophenylalanine (10B1-BPA). In order to explore the feasibility of applying NCT further to ocular melanoma, we investigated the boron concentrations in ocular melanomas and normal ocular tissues by 10B1-BPA administration to three patients, because success of NCT depends mainly upon selective boron accumulation in melanoma. In the first and second ocular melanoma patients, to whom 10B1-BPA fructose complex (total dose of 10B1-BPA: 170 mg/kg body weight) was administered orally in two divided doses, the boron concentrations in blood, vitreous body, sclera and retina choroidea were lower than that in melanoma examined. In the third conjunctival melanoma patient, to whom 10B1-BPA fructose complex (dose of 10B1-BPA: 85 mg/kg body weight) was administered by intravenous drip infusion, the average boron concentration in four melanoma samples was 17.7 ppm, which was estimated to be within the range necessary for melanoma eradication by thermal neutron irradiation. Boron uptake by lens, vitreous body, retina choroidea and sclera was much lower than that by melanoma. It was suggested that such a superficial ocular melanoma as iris melanoma can be destroyed by NCT, although vision may be affected--mainly due to cataract formation.