Warm up the tumor

Flu vaccine "warmed up" human tumors in mice

Polina Loseva, N+1

Scientists have proposed using the flu vaccine as an additional antitumor therapy. They tested their method on mice and found that vaccination stops tumor growth – however, only in the tissue where the neutralized viral particles hit. This works even in those mice that have been "infected" with human tumors – which means that it can theoretically work on humans. The work is published in the journal Proceedings of the National Academy of Sciences (Newman et al., Intratumoral injection of the seasonal flu shot converts immunologically cold tumors to hot and serves as an immunotherapy for cancer).

One of the main obstacles to the victory over cancer is the inactivity of the patient's own immune system. In some cases, immune cells manage to get inside the tumor and start the inflammatory process there – such tumors are called "hot", the chances of survival and cure in patients with such tumors are increased. It is much more difficult to cope with "cold" tumors that avoid the immune system and do not let its cells inside.

You can try to cope with this problem with the help of another, external stimulus of the immune system. The fact is that tumor cells can suppress the activity of immune cells. And if you introduce some obviously alien pathogen into the body, then the total number of pro-inflammatory proteins and active immune cells in the body will increase, and at the same time the chances of penetrating the tumor will increase.

Jenna Newman The Rugers Cancer Research Institute and her colleagues suggested using the flu virus as such an irritant. They injected melanoma cells into the lungs of model mice, and when they took root, infected them with the flu. Under the influence of infection, the number of tumor foci decreased by half. And if, at the same time, mice were treated for cancer with checkpoint inhibitors, then the foci became two times less.

The researchers checked their assumptions on a medical database, selecting from there the medical histories of more than 30 thousand patients with lung cancer. It turned out that those of them who were hospitalized with the flu at least once during the illness survived several percent better compared to those who did not have the flu.

Then the researchers tried to repeat the same experiment, but with a different mouse tissue – skin. However, the influenza virus itself did not affect either the survival rate of mice or the number of tumors. Then the scientists tried to use a viral vaccine instead of the virus – and in this case, the mice again survived better than the control group, and the tumor size was three times smaller.

Scientists have tested whether the effect of the vaccine is able to spread within the tissue. To do this, they "infected" only one of the two lung mice with melanoma, and then injected them with an inactivated virus as a vaccine. Tumor growth has slowed down in both lungs – from this, doctors concluded that the immune response is enhanced in the tissue as a whole, and not only in the area of vaccine administration. Finally, the researchers replicated their experiment on a humanized human cancer model – mice that had grown a human tumor. They also had the introduction of the vaccine into the tumor or adjacent tissue helped to stop its growth.

Based on their data, the authors concluded that their method can also be used in humans. They emphasize that, unlike many other means of fighting a tumor, the flu vaccine is the least dangerous for the body and causes a minimum of side effects – it is not for nothing that it is recommended even to children. At the same time, vaccination could enhance the effects of other, more dangerous and unstable cancer therapies, such as checkpoint inhibitors.

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