Photodynamic therapy to treat breast cancer: proof of concept pre-clinical studies

Abstract

Breast cancer is the second leading cause of cancer-related deaths among women in the world. Concentered efforts have been made in recent years to develop therapies that are able to treat various forms of breast cancer more effectively. Targeted therapy in breast cancer is dictated by the expression of specific molecules such as hormone or growth factor receptors. However, these agents are ineffective in the treatment of metastatic disease, which is characterized by the presence of triple-negative breast cancers (TNBC). A promising alternative treatment is photodynamic therapy (PDT), consisting in tissue destruction by visible light in the presence of a photosensitizer substance and oxygen. Previous results have shown that PDT using methylene blue, as a photosensitizer (MB-PDT) is able to selectively eliminate tumor breast cells in vitro models of cultured cells in monolayer or in spheroids, being more aggressive with the triple negative ones. In order to further validate this therapy, it is essential to continue the evaluation of the effectiveness of MB-PDT in tumors in vivo. Therefore, in the present project, we set out to perform pre-clinical trials for MB-PDT, analyzing its effectiveness in activating the immune system and completely killing the tumoral cells, minimizing the chances of recurrence. It is important to note that, preliminary data indicate that the MB-PDT has potential to induce a pro-inflammatory response against tumoral cells, demonstrating the importance of continuing these studies. From a translational point of view, this project will help to clarify yet unknown molecular mechanisms and to demonstrate the efficacy of MB-PDT, both fundamental to the development and feasibility of this strategy for treatment of more aggressive tumors.