Benzamide imaging agent could lead to a novel therapy for metastatic melanoma

Average survival for metastatic melanoma patients is less than 5 percent after five years—a disheartening figure, but incorporating benzamide in a melanin-targeted SPECT radiotracer could lead to more treatment options down the road, according to a study published Nov. 16 in the Journal of Nuclear Medicine.

Almost 80 percent of cutaneous cancer deaths are related to malignant melanoma—the fifth most prevalent cancer in men and the sixth in women. Surgical removal is the first line of treatment, but the cancer is often recurrent and metastatic. This study revealed the results of a phase III clinical trial for I-123 BZA2 for the detection of melanoma metastases. Researchers compared the efficacy of the tracer with conventional F-18 FDG PET/CT for disease staging.

“We have demonstrated that I-123 BZA2 tumor accumulation was clearly correlated to melanin content of the melanoma metastases,” said Florent Cachin, MD, PhD, lead author of the study from the department of nuclear medicine at Jean Perrin Cancer Center, Clermont-Ferrand, France, in a release. “Thus, I -123 BZA2 could be theoretically used for the diagnosis of melanoma metastases. However, given its low sensitivity due to the high proportion of non-pigmented lesion in the natural course of metastatic melanoma, I-123 BZA2 cannot be used for melanoma staging. Such results could appear discouraging, but the concept of melanin targeting may offer a real opportunity for therapy.”

A total of 87 subjects were found to have 86 metastatic lesions. While FDG’s sensitivity was higher than BZA2, 80 percent vs. 23 percent, respectively, BZA2 had higher specificity, 86 percent vs. 54 percent. BZA2’s overall diagnostic sensitivity was logged at 75 percent and specificity at 70 percent.