Investigation of a vitamin B12 conjugate as a PET imaging probe

Oluwatayo F. Ikotun, Bernadette V. Marquez, Christopher H. Fazen, Anna R. Kahkoska, Robert P. Doyle, Suzanne E. Lapi

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Nutrient demand is a fundamental characteristic of rapidly proliferating cells. Vitamin B12 is vital for cell proliferation; thus neoplastic cells have an increased demand for this essential nutrient. In this study we exploited the vitamin B12 uptake pathway to probe the nutritional demand of proliferating cells with a radiolabeled B12 derivative in various preclinical tumor models. We describe the synthesis and biological evaluations of copper-64-labeled B12-ethylenediamine-benzyl-1,4,7- triazacyclononane-N,N′,N′′-triacetic acid (B 12-en-Bn-NOTA-64Cu), the first example of a B12 derivative for positron emission tomography (PET) imaging. Small-animal imaging and pharmacological evaluation show high tumor uptake ranging from 2.20 to 4.84-%-ID-g-1 at 6 h post-administration. Competition studies with excess native B12 resulted in a 95-% decrease in tumor accumulation, indicating the specificity of this radiopharmaceutical for B12 endocytotic transport proteins. These results show that a vitamin B12 PET radiopharmaceutical has potential utility for non-invasive imaging of enhanced nutrient demand in proliferating cells. Co-opting cobalamin: Vitamin B12 is an essential nutrient for all proliferating cells. Rapid proliferation is a common hallmark of cancer; consequently, neoplastic cells have an increased demand for vitamin B12. We exploited the vitamin B12 uptake pathway to non-invasively probe the nutrient demand of cancer cells. The synthesis, characterization, and tumor-homing properties of a vitamin B12 PET radiotracer are described.

Original languageEnglish (US)
Pages (from-to)1244-1251
Number of pages8
Issue number6
StatePublished - Jun 2014


  • CD320
  • cobalamin
  • positron emission tomography
  • radiochemistry
  • vitamins

ASJC Scopus subject areas

  • Drug Discovery
  • General Pharmacology, Toxicology and Pharmaceutics
  • Molecular Medicine
  • Biochemistry
  • Pharmacology
  • Organic Chemistry


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