CHUM research unlocks path to stronger breast cancer virus therapy

A Montreal research team has identified a mechanism that could make some of the most difficult breast cancers vulnerable to viral therapy.

Researcher Marie-Claude Bourgeois-Daigneault and her colleagues at the Centre hospitalier de l'Université de Montréal discovered that estrogen blocks a natural cellular defense pathway called NF-kappaB, which normally protects cells from viruses. When this defense mechanism is blocked, cancer cells become more sensitive to oncolytic virus treatment.

"We realized that there were certain types of breast cancer that were much more sensitive than others," Bourgeois-Daigneault explained. "Then we were able to identify which patients would respond best to our treatment."

The findings are particularly significant for triple-negative breast cancers, among the most difficult to treat. The research suggests it's now possible to make tumors that are currently immune to viral therapy sensitive to the approach.

Bourgeois-Daigneault noted that oncolytic viruses are designed to specifically attack cancerous tumors, making the treatment safe for the rest of the body. However, the discovery also revealed a downside: hormonal treatments used as a first-line cancer defense can reduce the effectiveness of oncolytic viruses by blocking estrogen.

The next step is combining oncolytic viruses with drugs that block NF-kappaB, which could open the door to more flexible treatments adapted to clinical needs and applicable to other solid cancers. The findings were published in the journal Molecular Therapy.