- Synthesis and evaluation of novel radioiodinated benzamides for malignant melanoma
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The imaging potential of a series of [123I]benzamides was studied in mice bearing B16F0 melanoma tumors. Compound [123I]25 exhibited tumor uptake >8 %ID/g at 1 h, while that of [123I]14d and [123I]25 reached a maximum of 9-12 %ID/g at 6 h. Standardized uptake values of [123I]14d were higher than 100 between 24 and 72 h after injection. In haloperidol treated animals, the tumor uptake of [ 123I]14d was not significantly different to controls, while significant reduction of [123I]25 uptake was observed, supporting that [123I]14d uptake relates to melanin interaction, whereas part of the mechanism of [123I]25 uptake is related to its σ1-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.
- Pham, Tien Q.,Greguric, Ivan,Liu, Xiang,Berghofer, Paula,Ballantyne, Patrice,Chapman, Janette,Mattner, Filomena,Dikic, Branko,Jackson, Timothy,Loc'h, Christian,Katsifis, Andrew
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p. 3561 - 3572
(2008/02/09)
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- Radioiodinated N-(2-diethylaminoethyl)benzamide derivatives with high melanoma uptake: Structure-affinity relationships, metabolic fate, and intracellular localization
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Several radioiodinated N-(dialkylaminoalkyl)benzamides have been used for planar scintigraphy and single-photon emission computed tomography (SPECT) of melanoma metastases. In a quest for improved melanoma uptake and tissue selectivity, structure-activity studies for N-(2-diethylaminoethyl)benzamides with variation of phenyl substituents were performed using C57B1/6 mice bearing B16 melanoma. Compounds 2 (4-amino-5-bromo-N-(2-diethylaminoethyl)-3-[131I]iodo-2-methoxybenzamide) and 6 (4-acetamido-N-(2-diethylaminoethyl)-5-[131I]iodo-2-methoxybenzamide) showed at 6 h post iv injection, for example, melanoma uptake of 16.6 and 23.2% ID/g, respectively (mean values, n = 3). Uptake was 3-5 times higher (P 1-receptor affinities of K(i) = 0.278 ± 0.018 and 5.19 ± 0.40 μM, respectively. Uptake studies with IMBA (N-(2-diethylaminoethyl)-3-[131I]-iodo-4-methoxybenzamide) or BZA (N-(2-diethylaminoethyl)-4-[131I]iodobenzamide) showed that with increasing dose of unlabeled compound the measured uptake of label was unchanged (IMBA) or even enhanced (BZA) while receptor binding of label decreased. Differential and equilibrium density-gradient centrifugation revealed that most of the radioactivity from labeled IMBA was associated with fractions containing melanin granules. Thus, structure-activity studies indicate that blood clearance rates and metabolic stability are the main determinants for benzamide uptake in melanoma. The high uptake and slow clearance of 6 offer considerable potential for melanoma imaging in patients, and this compound may also prove to be useful for radionuclide therapy.
- Eisenhut,Hull,Mohammed,Mier,Lay,Just,Gorgas,Lehmann,Haberkorn
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p. 3913 - 3922
(2007/10/03)
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