New PET tracer may improve melanoma detection

A novel radiotracer tested for the first time in humans may help improve the detection of primary and metastatic melanoma, a highly aggressive form of skin cancer, according to a study published in the January issue of the Journal of Nuclear Medicine.

The new tracer, N-(2-(diethylamino)-ethyl)-18F-5-fluoropicolinamide (18F-P3BZA) is designed to target the melanin pigment in melanoma lesions which often affects the behavior of such cancers. Melanin production is found to decrease overall survival in metastatic patients.

“While melanin-targeted PET probes have been studied in small animal models for a long time, this is the first time such a probe has been successfully translated into clinical evaluation,” said Zhen Cheng, PhD, of Stanford University, in a news release. “Our research shows that 18F-P3BZA is safe and, moreover, it is highly promising for clinical diagnosis and staging of melanoma.”

The researchers injected six healthy patients with 18F-P3BZA who then underwent whole-body PET/CT scans and blood tests to determine biodistribution, pharmacokinetic and radiation dosimetry at 10 minutes, one hour, two hours and four hours following the injection. Another five patients with suspected melanoma received 18F-P3BZA at 10 minutes and one hour. To compare diagnostic ability, all participants received 18F-FDG PET/CT scans on the third day.

Results showed 18F-P3BZA was safe and able to “clearly” define melanoma tumors, the group wrote.

“Given its specific melanoma-imaging capability, 18F-P3BZA is expected to be a new probe which may overcome some of the limitations of 18F-FDG, such as the false positive of inflammation and a substantially lower tumor-to-muscle contrast compared with 18F-P3BZA,” Cheng said in the release. “Therefore, 18F-P3BZA may improve melanoma and metastasis detection and help guide therapeutic planning for melanoma patients.”