Agent offers 3D view of colon cancer via dual-modality virtual colonoscopy

CONTEXT: Building on established methods for CT virtual colonoscopy, Dr. Jamey Weichert, an associate professor of radiology at the University of Wisconsin, Madison, and colleagues tested a method for colonic tumor detection and characterization using PET/CT imaging. Iodine-124 NM404 (a radioiodinated phospholipid ether analog) was used as a PET tracer. NM404 has shown prominent tumor avidity and prolonged tumor retention in more than 30 preclinical malignant tumor types and in early clinical evaluation of lung cancer patients. Fluorine-18 FDG-PET was used for comparison. When labeled with iodine-125 or other radioisotopes commonly used in radiotherapy, NM404 has also shown promise as a radioimmunotherapeutic agent.

RESULTS: Two PIRC rats (a transgenic model for testing colon cancer progression) were injected with F-18 FDG followed 24 hours later by an injection of 124I-NM404. MicroPET and microCT scans were performed immediately following FDG injection and at 24 and 96 hours after NM404 injection. The in vivo NM404 microPET/microCT data distinguished three lesions as adenocarcinomas. Results confirmed a high degree of specificity for malignancy with NM404, while FDG did not differentiate between malignant and benign lesions.

IMAGE: In vivo microCT virtual colonoscopy fly-through of a PIRC rat indicates NM404 uptake in three potentially cancerous lesions.

IMPLICATIONS: The study is part of a larger program to establish clinical trials for NM404 dual-modality virtual colonoscopy. Future research will calculate standardized uptake values of NM404 versus FDG in colonic lesions in greater numbers of mice.