PT  - JOURNAL ARTICLE
AU  - Sah, Bert-Ram
AU  - Schibli, Roger
AU  - Waibel, Robert
AU  - von Boehmer, Lotta
AU  - Bläuenstein, Peter
AU  - Nexo, Ebba
AU  - Johayem, Anass
AU  - Fischer, Eliane
AU  - Müller, Ennio
AU  - Soyka, Jan D.
AU  - Knuth, Alexander K.
AU  - Haerle, Stefan K.
AU  - Schubiger, Pius August
AU  - Schaefer, Niklaus G.
AU  - Burger, Irene A.
TI  - Tumor Imaging in Patients with Advanced Tumors Using a New <sup>99m</sup>Tc-Radiolabeled Vitamin B12 Derivative
AID  - 10.2967/jnumed.113.122499
DP  - 2014 Jan 01
TA  - Journal of Nuclear Medicine
PG  - 43--49
VI  - 55
IP  - 1
4099  - http://jnm.snmjournals.org/content/55/1/43.short
4100  - http://jnm.snmjournals.org/content/55/1/43.full
SO  - J Nucl Med2014 Jan 01; 55
AB  - Targeting cancer cells with vitamin B12 (cobalamin) is hampered by unwanted physiologic tissue uptake mediated by transcobalamin. Adhering to good manufacturing practice, we have developed a new 99mTc-cobalamin derivative (99mTc(CO)3-[(4-amido-butyl)-pyridin-2-yl-methyl-amino-acetato] cobalamin, 99mTc-PAMA-cobalamin). The derivative shows no binding to transcobalamin but is recognized by haptocorrin, a protein present in the circulation and notably expressed in many tumor cells. In this prospective study, we investigated cancer-specific uptake of 99mTc-PAMA-cobalamin in 10 patients with various metastatic tumors. Methods: Ten patients with biopsy-proven metastatic cancer were included. Dynamic imaging was started immediately after injection of 300–500 MBq of 99mTc-PAMA-cobalamin, and whole-body scintigrams were obtained at 10, 30, 60, 120, and 240 min and after 24 h. The relative tumor activity using SPECT/CT over the tumor region after 4 h was measured in comparison to disease-free lung parenchyma. Patients 3–10 received between 20 and 1,000 μg of cobalamin intravenously before injection of 99mTc-PAMA-cobalamin. The study population comprised 4 patients with adenocarcinomas of the lung, 3 with squamous cell carcinomas of the hypopharyngeal region, 1 with prostate adenocarcinoma, 1 with breast, and 1 with colon adenocarcinoma. Results: The median age of the study group was 61 ± 11 y. Six of 10 patients showed positive tumor uptake on 99mTc-PAMA-cobalamin whole-body scintigraphy. The scan was positive in 1 patient with colon adenocarcinoma, in 3 of 4 lung adenocarcinomas, in 1 of 3 hypopharyngeal squamous cell carcinomas, and in 1 breast adenocarcinoma. Renal uptake was between 1% and 3% for the left kidney. Predosing with cobalamin increased the tumor uptake and improved blood-pool clearance. The best image quality was achieved with a predose of 20–100 ug of cold cobalamin. The mean patient dose was 2.7 ± 0.9 mSv/patient. Conclusion: To our knowledge, we report for the first time on 99mTc-PAMA-cobalamin imaging in patients with metastatic cancer disease and show that tumor targeting is feasible.