Iodide benzamides for the in-vivo detection of melanoma and metastases.

The aim of this work was to synthesize, label and evaluate in vivo [I]N-(2-diethylaminoethyl)-3-iodo-4-methoxybenzamide ([I]IMBA) as a radiotracer for B16-F0 melanoma cells, in C57 mice bearing a subcutaneous melanoma tumour and experimentally induced lung metastases. The average radio-iodination yield achieved, after labelling and Sep-Pak purification, was 65%, with a radiochemical purity of > or = 96%. Biodistribution studies using [I]IMBA (2.2 GBq/micromol) showed high specific tumour uptake, with low non-target tissue background, due to a rapid renal clearance from the animal body (corporal retention was 19.7 +/- 7.1% of the injected dose at 6 h and 4.00 +/- 2.4% of the injected dose at 24 h). The very high targeting efficiency of this radiopharmaceutical was also confirmed by images in which primary subcutaneous tumour and induced lung metastases were clearly visualized. In addition, a clear correlation was found between the uptake of radioactivity in the lungs (percentage of the injected dose per gram of tissue) and the number of metastases carried by them.