Spanish researchers have shown in mice the antitumor effect of a type of virus hidden in mesenchymal stem cells. The therapy manages to activate the subject’s immune response and opens the door to the possibility of a universal treatment. The work has just been published in Cancer Immunology.
A novel therapy, known as Celyvir, has demonstrated the antitumor effect of oncolytic viruses —capable of infecting and decomposing cancer cells— hidden in mesenchymal stem cells, i.e. those that can give rise to several types of cells of skeletal tissues, like cartilage, bone and fat.
The research, conducted in mice in the Cell Biotechnology Unit of the Carlos III Health Institute, combines cells and viruses to act as a kind of cellular Trojan horse that awakens the antitumor immune system.
“Our work has confirmed in mice that the mesenchymal stem cells that carry the antitumor virus could be obtained both from the patient himself (syngeneic cells) and from a donor (allogeneic cells), reducing the volume of the tumor by 35%,” explains Álvaro Morales , lead author of the study.
In both cases, the treatment not only succeeded in activating the immune response, but also increased the infiltration of certain anticancer immune cells (the so-called N2 antitumor neutrophils) in the treated cancers.
Previous work has indicated that this greater infiltration of the immune system in the tumor is extensively related to a better prognosis of the disease and a greater response to other immunotherapies.
A universal treatment
Oncolytic viruses are those that selectively replicate in tumor cells, destroying them. The problem with this therapy is that the virus does not reach the tumor on its own, since the immune system usually exerts an antiviral response against it.
To solve it, experts have used mesenchymal stem cells, transporting those viruses inside them as if they were a cellular Trojan horse. In this way, the oncolytic virus reaches the tumor within the stem cells themselves, where it is released and produces a greater antitumor response.
“The results open the possibility of producing a universal treatment of mesenchymal stem cells as transporters of the oncolytic virus without the need to obtain them from patients, which facilitates the speed and availability of this viroimmunotherapy,” concludes Morales.