Injecting the Flu Vaccine Into a Tumor Gets the Immune System To Attack It

"Injecting the flu vaccine into a tumor gets the immune system to attack it," reports Ars Technica.

Joe_NoOne (Slashdot reader #48,818) shared their report:
This is one of those ideas that seems nuts but had so many earlier results pointing toward it working that it was really just a matter of time before someone tried it. To understand it, you have to overcome the idea that the immune system is always diffuse, composed of cells that wander the blood stream. Instead, immune cells organize at the sites of infections (or tumors), where they communicate with each other to both organize an attack and limit that attack so that healthy tissue isn't also targeted.

From this perspective, the immune system's inability to eliminate tumor cells isn't only the product of their similarities to healthy cells. It's also the product of the signaling networks that help restrain the immune system to prevent it from attacking normal cells... A number of recently developed drugs help release this self-imposed limit, winning their developers Nobel Prizes in the process. These drugs convert a "cold" immune response, dominated by signaling that shuts things down, into a "hot" one that is able to attack a tumor...

[More recently] researchers identified over 30,000 people being treated for lung cancer and found those who also received an influenza diagnosis. You might expect that the combination of the flu and cancer would be very difficult for those patients, but instead, they had lower mortality than the patients who didn't get the flu. For more detailed tests, the researchers moved to mice, using melanoma cells that can form tumors when transplanted into the lungs of the mice... Having an active influenza virus infection reduced the ability of the melanoma cells to establish themselves in the lung. The effect isn't limited to the location of the infection, though, as tumors in the lung that wasn't infected were also inhibited. The effects were similar when breast cancer cells were placed into the lung, as well. All of this is consistent with the immune stimulation provided by a pathogen. The stimulation causes a general activation of the immune system that releases it from limits on its activity that prevent it from attacking tumor cells....

[T]he researchers obtained this year's flu vaccine and injected it into the sites of tumors. Not only was tumor growth slowed, but the mice ended up immune to the flu virus.... [T]he story does fit in well with the general consensus that the immune system can be a powerful tool against cancer, provided it can be mobilized properly. And, in at least some cases, a flu vaccine just might do the trick.