Method for assessing photodynamic cancer therapy effectiveness developed at UNN

Biophysicists at Lobachevsky University have developed a photosensitizer that allows assessing the effectiveness of photodynamic anticancer therapy (PDT) in real time.

The porphyrazine-based compound has a unique set of properties and has no analogues in modern photodynamic therapy. The substance is both an antitumour agent and a cell viscosity sensor. The higher the viscosity of the intracellular medium, the higher the chance that a tumour is destroyed. 

"The photosensitizer is injected intravenously and accumulates selectively in the tumour, the tumour is then irradiated with light. As a result, energy is transferred to the photosensitizer, which activates oxygen that destroys the cancer cells. As they die, the cytoplasm becomes viscous. At this point, the photosensitizer changes its luminescence. We use special sensors to monitor the luminescence level. If the luminescence parameters have changed, it means that the tumour cell will certainly die," said Natalia Shilyagina, senior researcher at the UNN Department of Biophysics.

Depending on the luminescence of the photosensitizer, the dose of light required to destroy the tumour can be selected within a few minutes, depending on the individual characteristics of the disease. In contrast, existing PDT methods rely on standard treatment algorithms, require repeated diagnostics of the tumour, and often require new therapy sessions.

"Photodynamic therapy is an excellent way of minimally invasive treatment when the tumour is located at a small depth and can be eliminated without resorting to surgery. Our goal is to achieve maximum effectiveness of PDT with minimal risk to healthy tissues, so that the tumour death mechanism can be triggered in one session. With this approach, there will be fewer recurrences and side effects, and the patient's stress level will be reduced. Finally, it will save time for the doctor and the patient. If we manage to introduce our method into clinical practice, photodynamic therapy will become more personalised," explained Natalia Shilyagina.

Moreover, the photosensitizers developed at Lobachevsky University can be used to visualise tumour boundaries during surgery. Another advantage of the compound is its low skin phototoxicity, which reduces patients' sensitivity to ordinary light after a session of photodynamic therapy.

"In various experiments on cells and laboratory animals, the substance has shown its effectiveness. Experiments on mice have demonstrated not only that the tumour has disappeared, but also that the tissue has healed. To take the next step, we need to scale up the trials. Today, we continue to improve the compound with the help of fine chemical tuning, creating the "ideal photosensitizer". Its various variants can be used not only in medicine, but also to study intracellular processes," Natalia Shilyagina said.

The photosensitizers were synthesised at the Institute of Organometallic Chemistry of the Russian Academy of Sciences. Medical specialists of the Nizhny Novgorod Regional Clinical Oncological Clinic and the Semashko Nizhny Novgorod Regional Clinical Hospital also contributed to the project. The equipment for monitoring the state of the photosensitizer was developed at the Institute of Applied Physics of the Russian Academy of Sciences.

The research in this project has been ongoing for 10 years. The results of the work were summarised in an article published in the international journal Biophysical Reviews in 2023.