Potential tumor or organ-imaging agents. 30. Radioiodinated phospholipid ethers.

A radioiodinated analogue of a naturally occurring alkyl lysophospholipid (ALP) was synthesized for evaluation as a potential tumor-localizing imaging agent. rac-1-[12-(m-Iodophenyl)dodecyl]-2-methylglycero-3-phosphocholine (ET-12IP-OMe, 14) was radiolabeled with iodine-125 via an isotope-exchange procedure. Tissue distribution studies with [125I]ET-12IP-OMe in tumor-bearing rats revealed an immediate tumor uptake of radioactivity. Although radioactivity was also present in nontarget tissues at this time, clearance of tracer from the tumor was much slower and thus provided a suitable tumor to nontarget tissue ratio at 24 h. As a result of this selective accumulation, it was possible to clearly delineate the tumor with gamma-camera scintigraphy.