Immunotherapy to treat breast tumours

Toni Celià-Terrassa

Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Spain

Immunotherapy has revolutionised the treatment of some types of cancer, such as melanoma and certain lung cancers, while in others, such as breast cancer, which is the second leading cause of cancer death among women, it is still not very effective. The reason, according to the researchers at IMIM, seems to be a failure in the mechanism of a protein, LCoR.

Under normal conditions, this protein allows the immune system to destroy diseased cells. Specifically, LCoR ensures that these cancer cells display antigens – molecules that the body's defences recognise – on their outer membrane, allowing them to identify cancer cells and attack them. However, in some breast cancers, this mechanism fails to work and the cancer cells do not display antigens on their membranes, so they become invisible to the immune system. This means that immunotherapy treatments are not effective, and resistance to these treatments builds up.

The IMIM researchers have developed an innovative experimental system based on messenger RNA, very similar to the technology used by the Moderna and Pfizer vaccines developed to combat COVID-19. By this means, they produce LCoR and make tumour cells visible and sensitive to the immune system again. They have also observed that they can increase the efficacy of immunotherapy treatments against breast cancer by increasing the levels of this protein.