18-(P-(124I)-Iodophenyl)octadecyl phosphocholine
Iodine I 124 Iopofosine is a radioconjugate composed of the radioisotope iodine I 124 covalently attached to the alkylphospholipid ether (PLE) analog iopofosine, with potential imaging activity upon positron emission tomography (PET). Upon administration, iodine I 124 iopofosine is selectively taken up by tumor cells via membrane lipid rafts and accumulates in tumor cells. The accumulation of this agent is due to a decreased ability of tumor cells to metabolize PLEs because certain tumor cells have lower levels of the enzyme phospholipase-D (PLD), in comparison to normal cells. As tumor cells are unable to metabolize and eliminate iopofosine, tumor cells can be visualized upon PET imaging. Lipid rafts, specialized microdomains of plasma membrane, are overexpressed in cancer cells compared to normal cells. In addition, the radioiodine moiety of this agent is resistant to de-iodination. PLD is an enzyme found in the cell membrane of normal cells that degrades phospholipids.