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sup 123^I-BZA2 as a Melanin-Targeted Radiotracer for the Identification of Melanoma Metastases: Results and Perspectives of a Multicenter Phase III Clinical Trial
Ist Teil von
The Journal of nuclear medicine (1978), 2014-01, Vol.55 (1), p.15
Ort / Verlag
New York: Society of Nuclear Medicine
Erscheinungsjahr
2014
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
Our group has developed a new radiopharmaceutical, ^sup 123^I-N-(2-diethylaminoethyl)-2-iodobenzamide (^sup 123^I-BZA2), a benzamide derivative able to bind to melanin pigment in melanoma cells. In a prospective and multicentric phase III clinical study, the value of 18F-FDG PET/CT and ^sup 123^I-BZA2 scintigraphy was compared for melanoma staging. Patients with a past history of cutaneous or ocular melanoma were included from 8 hospitals. ^sup 18^F-FDG imaging was performed according to a standard PET protocol. Whole-body, static planar, and SPECT/CT (if available) images were acquired 4 h after injection of a 2 MBq/kg dose of ^sup 123^I-BZA2. ^sup 18^F-FDG and ^sup 123^I-BZA2 sensitivity and specificity for the diagnosis of melanoma metastasis were calculated and compared on both a lesion basis and a patient basis. True-positive and true-negative lesion status was determined after 6 mo of clinical follow-up or according to lesion biopsies (if available). Melanin content in biopsies was evaluated with the standard Fontana-Masson silver method and was correlated with ^sup 123^I-BZA2 uptake. Based on statistical analysis, the number of inclusions was estimated at 186. In all, 87 patients were enrolled from 2008 to 2010. Of these, 45 (52%) had metastases. A total of 338 imaging abnormalities were analyzed; 86 lesions were considered metastases, and 20 of 25 lesion biopsies found melanoma metastases. In a patient-based analysis, the sensitivity of ^sup 18^F-FDG for diagnosis of melanoma metastases was higher than that of ^sup 123^I-BZA2, at 87% and 39%, respectively (P < 0.05). For specificity, ^sup 18^F-FDG and ^sup 123^I-BZA2 were not statistically different, at 78% and 94%, respectively. In a lesion-based analysis, the sensitivity of ^sup 18^F-FDG was statistically higher than that of ^sup 123^I-BZA2 (80% vs. 23%, P < 0.05). The specificity of ^sup 18^F-FDG was lower than that of ^sup 123^I-BZA2 (54% vs. 86%, P < 0.05). According to biopsy analysis, only 9 of 20 metastatic lesions (45%) were pigmented with high melanin content. ^sup 123^I-BZA2 imaging was positive for 6 of 8 melanin-positive lesions, fairly positive for 3 of 10 melanin-negative lesions, and negative for 7 of 10 melanin-negative lesions. The sensitivity and specificity of ^sup 123^I-BZA2 for the diagnosis of melanin-positive lesions were 75% and 70%, respectively. Because of a low ^sup 123^I-BZA2 sensitivity, this clinical trial was prematurely closed after 87 patients had been included. This study confirms the value of ^sup 18^F-FDG PET/CT for melanoma staging and strengthens the high accuracy of ^sup 123^I-BZA2 for diagnosis of melanin-positive metastatic melanoma. Moreover, benzamide derivatives radiolabeled with therapeutic radionuclide may offer a new strategy for the treatment of metastatic melanoma patients harboring melanin-positive metastases.