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This Article Figures Only Full Text Full Text (PDF) Supplemental Data All Versions of this Article: jnumed.109.066175v1 50/10/1692    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JNM Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Ren, G. Articles by Cheng, Z. PubMed PubMed Citation Articles by Ren, G. Articles by Cheng, Z.

Melanin-Targeted Preclinical PET Imaging of Melanoma Metastasis

¹ Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, Stanford, California; and ² Division of Nuclear Medicine, Department of Radiology, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts

Correspondence: For correspondence or reprints contact: Zhen Cheng, Molecular Imaging Program at Stanford, Department of Radiology, 1201 Welch Rd., Lucas Expansion, P020A, Stanford University, Stanford, CA 94305. E-mail: zcheng{at}stanford.edu

Dialkylamino-alkyl-benzamides possess an affinity for melanin, suggesting that labeling of such benzamides with ¹⁸F could potentially produce melanin-targeted PET probes able to identify melanotic melanoma metastases in vivo with high sensitivity and specificity. Methods: In this study, N-[2-(diethylamino)ethyl]-4-¹⁸F-fluorobenzamide (¹⁸F-FBZA) was synthesized via a 1-step conjugation reaction. The -receptor binding affinity of ¹⁹F-FBZA was determined along with the in vitro cellular uptake of radiofluorinated ¹⁸F-FBZA in B16F10 cells. In vivo distribution and small-animal PET studies were conducted on mice bearing B16F10 melanoma, A375M amelanotic melanoma, and U87MG tumors, and comparative studies were performed with ¹⁸F-FDG PET in the melanoma models. Results: In vitro, uptake of ¹⁸F-FBZA was significantly higher in B16F10 cells treated with L-tyrosine (P < 0.001). In vivo, ¹⁸F-FBZA displayed significant tumor uptake; at 2 h, 5.94 ± 1.83 percentage injected dose (%ID) per gram was observed in B16F10 tumors and only 0.75 ± 0.09 %ID/g and 0.56 ± 0.13 %ID/g was observed in amelanotic A375M and U87MG tumors, respectively. Lung uptake was significantly higher in murine lungs bearing melanotic B16F10 pulmonary metastases than in normal murine lungs (P < 0.01). Small-animal PET clearly identified melanotic lesions in both primary and pulmonary metastasis B16F10 tumor models. Coregistered micro-CT with small-animal PET along with biopsies further confirmed the presence of tumor lesions in the mouse lungs. Conclusion: ¹⁸F-FBZA specifically targets primary and metastatic melanotic melanoma lesions with high tumor uptake and may have translational potential.

Key Words: malignant melanoma • melanin • PET • imaging • ¹⁸F

COPYRIGHT © 2009 by the Society of Nuclear Medicine, Inc.

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