A Montreal team has identified a mechanism that increases the effectiveness of oncolytic viruses in the treatment of breast cancer, particularly in the face of the most recalcitrant breast cancers.
This work suggests that it is possible to make tumors that are currently immune to viral therapy, in particular triple-negative breast cancers, which are among the most difficult to treat, sensitive to viral therapy.
“We realized that there were certain types of breast cancer that were much more sensitive than others,” explained the study’s author, researcher Marie-Claude Bourgeois-Daigneault of the Centre hospitalier de l’Université de Montréal. Then, we were able to identify which patients would respond best to our treatment.”
In short, Bourgeois-Daigneault and her colleagues have discovered that estrogen blocks a natural cellular defense pathway, called NF-kappaB, that normally protects cells from viruses.
Once this defense mechanism is blocked, the cancer naturally becomes more sensitive to viral treatment.
“This hormone makes our treatment better,” said Bourgeois-Daigneault. Because if we are able to block NF-kappaB, the cells can no longer protect themselves against infection.”
And all of this is safe for the rest of the body, since oncolytic viruses are designed to specifically attack cancerous tumours, she said.
On the other hand, this discovery also reveals that hormonal treatments used as a first line of defense against cancer can reduce the effectiveness of oncolytic viruses by blocking estrogen ― since without estrogen, cells can defend themselves more effectively against the virus.
The idea would now be to combine oncolytic viruses with drugs that block NF-kappaB to pave the way for more flexible, inclusive treatments that are better adapted to clinical needs, it was explained in a press release.
This strategy would open the door to all breast cancers, and even to other solid cancers that do not depend on hormones, it is claimed.
“Even patients who did not respond to our treatment could now respond to it thanks to what we have identified,” predicted Bourgeois-Daigneault.
The findings of this study were published in the journal Molecular Therapy.
–This report by La Presse Canadienne was translated by CityNews
