Potential radiopharmaceuticals for the detection of ocular melanoma. Part II. Iodoquinoline derivatives and 67Ga-citrate.

The uptake and distribution of several 4-(substituted amino)-iodoquinolines, 131I-labelled, and of 67Ga-citrate were investigated in Syrian golden hamsters with Greene melanomas. Because of its uptake in the melanoma (tumour/eye ratio 8.9), 4-(dimethylamino-ethylamino)-7-iodoquinoline (NM113) was selected for further investigations as a possible radiopharmaceutical for ocular scintigraphy when labelled with 123I. High uptake of NM113 turned out to be incidental and could not be favourably influenced by several pharmacological pretreatments. Affinity for melanin, as shown in in vitro experiments, unfavourably influences NM113 tumour-to-eye ratios. In comparison with 67Ga-citrate, the latter, with a high tumour-to-eye ratio (44.8 after 24 h) is more promising in patient studies in which NM113 123I was not.