New radiotracer for imaging cancer cells

According to the Centre, [99mTc]Tc-DB15 consists of a diagnostic radioactive technetium isomer Tc-99m, bound associated with a GRPR (Gastrin-Releasing Peptide Receptor) antagonist found in the cells of certain types of cancer.

An isomer of a given element is an element with the same mass and atomic number (with the same number of protons and neutrons in the nucleus), where at least one of the nucleons is at a higher energy level.

Tc-99m is mainly obtained from the decay of molybdenum-99 in radionuclide generators, manufactured by POLATOM, among others.

The use of the compound [99mTc]Tc-DB15 allows to detect cancer thanks to the use of Tc-99m, which emits photons with energies in the gamma range during its decay. These photons are then recorded by a SPECT (Single Photon Emission Computed Tomography) scanner. This device, similar to PET (Positron Emission Tomography), observes the photons from Tc-99m decay, and after processing with a special algorithm it generates a 3D image of the patient with clearly visible sites of photon emission from the decay of the radioisotope. Technetium-99m, bound to the receptor antagonist, accumulates in cells with increased GRPR density, i.e. in cancer cells. As a result, it allows to locate cancer cells and determine their activity.

The Centre said: “Cell receptor antagonists used in diagnostics can also potentially be used in theranostics, i.e. therapeutics combined with diagnostics, by using ionising radiation to kill cancer cells.”

According to the National Centre for Nuclear Research, preliminary studies on the new radiotracer, carried out in vitro on breast cancer and prostate cancer cells, show that cancer cells accumulate the radiotracer well.

Further in vivo studies were conducted in mice implanted with GRPR-positive prostate and breast cancer cells. The results show that after administration, the preparation quickly accumulates in cancer cells. After the safety of the study drug was confirmed, two female patients suffering from breast cancer whose cells had GRPR receptors were subjected to this method of imaging. In a press release the Centre said: “The research was carried out based on a research protocol approved by the Bioethics Committee of the Poznan University of Medical Sciences. The patients gave their informed consent to participate in the study.”

The Centre’s Professor Renata Mikołajczak added: “Modern medicine uses very similar strategies to the one we propose, such as the treatment of breast cancer with HER2 receptors.

“The new procedure, based on the use of GRPR antagonists, would be another personalized method in the treatment of a specific type of cancer cells, and increasing the number of methods allows to precisely and effectively treat various types of cancer.”

PAP - Science in Poland

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