On September 23, 2020, scientists received data on the first phase of clinical trials of a new radiopharmaceutical to diagnose an aggressive form of breast cancer. It was developed by the Tomsk Polytechnic University on the basis of technology unique to Russia, which uses a scaffold protein. The first phase of clinical trials was conducted last year at the Oncological Research Institute of the Tomsk National Research Medical Center of the Russian Academy of Sciences. Twenty-nine patients have participated in the trials and the drug has been proven successful.

The results have been published in the Journal of Nuclear Medicine and were presented in September at the first Swedish-Russian online forum for young scientists.

The resulting radiopharmaceutical differs in structure and contains a scaffold protein and a radioactive isotope, technetium-99. The protein is responsible for precise detection of tumor cells on the basis of the antigen-antibody reaction, and the isotope helps visualize the locations of those cells. The position of the isotope and the tumor cell can be observed with a gamma camera. All oncology centers have these devices. Diagnostics done in this manner are considered extremely promising due to their accuracy and lack of toxicity. They have not yet been widely used as a matter of general practice.

The research team used ADAPT6, a scaffold protein specific to the Her2/neu tumor marker, a receptor on the surface of a tumor cell. The more receptors are present on a cell, the more aggressive the disease. From 15 to 20 percent of patients with breast cancer show an increased expression of this receptor. Up to two million Her2/neu receptors may be present on one cell.

“Treatment of this type of breast cancer involves expensive targeted drugs that require an accurate diagnosis to locate tumor cells and minimize the effect of drugs on healthy tissue. Morphological and immunohistochemical examination methods are the standard for diagnosing tumors. They are invasive and require tissue removal. Previously, no one has used radionuclides to diagnose Her2/neu receptors. Our drug is the first in this regard. Nevertheless, it will not replace standard methods, but will make the diagnosis even more precise,” said Olga Bragina, one of the authors and a research associate at the TPU Oncoteranostika Research Center.

In the first phase of clinical trials, patients were divided into three groups according to the dose of the drug. They were intravenously injected with 250, 500, and 1,000 micrograms. Experts point out that even the maximum dose of the new medicine is lower than the normal dose of standard drugs used to diagnose other cancers. Each patient was injected with the drug once.

Patients were scanned with a gamma camera in two, four, six, and 24 hours after administration to assess the rate of drug distribution and accumulation.

“Results show a significant difference in drug accumulation in tumors with overexpression of Her2/neu compared to tumors without this receptor and with a high tumor-liver ratio. This means that this drug may have metastasis in both the mammary gland and liver. In one case, the status of Her2/neu has been changed. A negative expression was found in one patient, which led to a change in treatment strategy. In another case, additional metastatic lesions were found in the thoracic vertebra and rib, which were not previously visible with conventional diagnostic methods,” Bragina said.

The drug still needs to be clinically tested at several stages.

“That was just the first step. The potential of the drug will continue to be determined in clinical trials. It is planned to be used for visualization in other organs. Further research phases can take several years. The drug will then have to go through a long certification phase in order to be available to patients in other clinics,” said Vladimir Chernov, head of the Radionuclide Diagnostics Department.