Development of high-specific-activity 68Ga-labeled DOTA-rhenium-cyclized α-MSH peptide analog to target MC1 receptors overexpressed by melanoma tumors

Melchor V. Cantorias, Said D. Figueroa, Thomas P. Quinn, John R. Lever, Timothy J. Hoffman, Lisa D. Watkinson, Terry L. Carmack, Cathy S. Cutler

Research output: Contribution to journalArticle


Introduction: A previous report on 68Ga-1,4,7,10-tetraazacyclodedecane-N,N′,N″,N′″-tetraacetic acid (DOTA)-Re(Arg11)CCMSH was shown to indicate the imaging agent's potency for early detection of metastatic melanoma. However, the main limiting factor to developing high-specific-activity 68Ga-DOTA-Re(Arg11)CCMSH is the short half-life of 68Ga, which precludes further purification of the agent. To circumvent this problem, we incorporated the microwave technique to rapidly radiolabel the peptide with 68Ga, thereby allowing enough time to include high-performance liquid chromatography (HPLC) purification in the overall procedure. Methods: DOTA-Re(Arg11)CCMSH was radiolabeled with 68Ga in 68Ga-DOTA-Re(Arg11)CCMSH was then administered on B16/F1 murine melanoma-bearing C57 mice to study its biodistribution and positron emission tomography (PET) imaging capability. Results: The production of high-specific-activity 68Ga-DOTA-Re(Arg11)CCMSH resulted in an improved tumor uptake [6.93±1.11%ID/g at 30 min postinjection (p.i.) and 6.27±1.60%ID/g at 1 h p.i.] and tumor retention (5.85±1.32%ID/g at 4 h p.i.). Receptor-mediated tumor uptake was verified by blocking studies. Furthermore, high-resolution PET images of the tumor were obtained, owing to high tumor-to-nontarget organ ratios at an early time point (i.e., at 1 h biodistribution: tumor/blood, 14.3; tumor/muscle, 89.6; tumor/skin, 12.3) and fast clearance of the labeled peptide from kidney and other healthy tissues. Conclusion: High-specific-activity 68Ga-DOTA-Re(Arg11)CCMSH may have a potential role in the early diagnosis of metastasized melanoma.

Original languageEnglish (US)
Pages (from-to)505-513
Number of pages9
JournalNuclear Medicine and Biology
Issue number5
Publication statusPublished - Jul 2009
Externally publishedYes



  • α-Melanocyte-stimulating hormone
  • Ga-68
  • HPLC purification
  • Microwave labeling
  • PET
  • Specific activity

ASJC Scopus subject areas

  • Cancer Research
  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging

Cite this