PET Imaging Could Improve Cancer Treatment

Positron emission tomography (PET) tracking of liposomal nanomedicines could be used to validate drug delivery, according to a new study.

Developed by researcher at King’s College London (KCL; United Kingdom) Shaare Zedek Medical Center (Jerusalem, Israel), and other institutions, the PET radio-labeling method exploits the metal-chelating properties of certain drugs – bisphosphonates such as alendronate, and anthracyclines such as doxorubicin – and widely used ionophores in order to achieve excellent radio-labeling yields, purities, and stabilities with 89Zr, 52Mn, and 64Cu, and without needing to modify the nanomedicine components.

Imaging with PET in mouse models of breast and ovarian cancer showed that the drugs accumulate in tumors and metastatic tissues in varying therapeutic concentrations, and in most cases, at levels well above those in normal tissues. According to the study, in one mouse strain the nanomedicines unexpectedly showed up in the uterus, a result that would not have been detected without the PET imaging study. The study was published on October 26, 2016, in ACS Nano.

“This technique allows quantification of the biodistribution of a radio-labeled stealth liposomal nanomedicine containing alendronate that shows high uptake in primary tumors and metastatic organs,” concluded senior author Rafael Torres Martin de Rosales, PhD, of KCL, and colleagues. “The versatility, efficiency, simplicity, and GMP compatibility of this method may enable submicrodosing imaging studies of liposomal nanomedicines containing chelating drugs in humans, and may have clinical impact by facilitating the introduction of image-guided therapeutic strategies.”

Chelation involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and the single central atom of a metallic ion. The ligands are usually organic compounds, known as chelants or chelating agents. Chelation is useful for delivering nutritional supplements, in chelation therapy to remove toxic metals from the body, as contrast agents in MRI and PET scanning, in manufacturing using homogeneous catalysts, and in fertilizers.

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King’s College London
Shaare Zedek Medical Center