Synthesis and evaluation of novel radioiodinated benzamides for malignant melanoma

The imaging potential of a series of [I-123]benzamides was studied in mice bearing B16F0 melanoma tumors. Compound [I-123]25 exhibited tumor uptake > 8 %ID/g at 1 h, while that of [I-123]14d and [I-123]25 reached a maximum of 9-12 %ID/g at 6 h. Standardized uptake values of [I-123]14d were higher than 100 between 24 and 72 h after injection. In haloperidol treated animals, the tumor uptake of [I-123]14d was not significantly different to controls, while significant reduction of [I-123]25 uptake was observed, supporting that [I-123]14d uptake relates to melanin interaction, whereas part of the mechanism of [I-123]25 uptake is related to its sigma(1)-receptor affinity. Benzamides 14d and 25, which display rapid and high tumor uptake, appear to be promising imaging agents for melanoma detection, while 14d, which displays a long lasting and high melanoma/nontarget ratio, is more suitable for evaluation as a potential radiotherapeutic.