NM-404 I-124 ([124I]CLR-1404, LIGHT ) is a phospholipid ether analog labeled with iodine I 124, with a potential imaging property upon positron emission tomography (PET). Upon administration, NM-404 I-124 selectively accumulates in and is retained within tumor cells for a prolonged period of time due to the decreased activity of a phospholipase D (PLD), most likely isoform 1 of PLD, in tumor cells compared to normal cells. As tumor cells are unable to metabolize and eliminate MN404, tumor cells can be visualized upon PET imaging. In addition, NM-404 I-124 may provide a more accurate image of the tumor than imaging with the current standard. PLD is an enzyme found in the cell membrane of normal cells that degrades phospholipids. NM-404 I-124 enters cells predominately via lipid rafts, specialized microdomains of plasma membranes enriched in cholesterol and glycosphingolipids, which are found to be overexpressed 6-10 fold in malignant cells compared to normal cells. Although blood pool uptake in major vascular structures demonstrates high uptake initially, there is no significant CLR1404 uptake in normal brain tissue. Therefore, avid brain tumor uptake results in high tumor to back-ground signal and thus clear identification of viable tumor cells on PET scans. NM-404 I-124 selectively illuminated malignant tumors in 52 of 54 animal models of cancer, demonstrating evidence of broad-spectrum, cancer-selective uptake and retention. FDA granted orphan drug designation in the United States for NM-404 I-124 as a diagnostic for the management of glioma.