Natural killer cells (or NK cells), as part of the body´s immune system, can effectively fight cancer.
Unfortunately, they quickly lose their aggressiveness and hence are unable to reject solid tumors. Scientists from the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) have now discovered a cocktail consisting of three different immune mediators that leaves NK killer cells active over a long period of time. In mice, cocktail-boosted NK cells let tumors shrink. The cocktail was able to persistently activate human NK cells, too.
Fighting cancer using the body’s own defense system is a promising treatment approach. Immune therapies have even become clinical routine in treating a few cancers such as malignant melanoma and prostate cancer. Natural killer cells (or NK cells) are considered to be particularly suitable weapons against cancer. They are part of the innate immune system and respond to a wide range of cancer cells of diverse origin. Moreover, NK cells also kill tumor cells that have lost a specific target and go unnoticed by other immune cells.
“The big problem in using NK cells for therapy is their rapid loss of activity, hence their aggressiveness,” says Dr. Adelheid Cerwenka. Together with her team at the German Cancer Research Center (DKFZ), Cerwenka is trying to develop cancer therapies based on NK cells. “Although there are good treatment results for certain types of blood cancer, NK cells have been clinically effective in fighting solid tumors only in a few cases,” the immunologist explains.
Cerwenka’s team has now been the first to enhance the NK cells’ deadly potential in mice using a cocktail of three different immune mediators (interleukins 12, 15, and 18). NK cells that were activated in the culture dish and then injected into cancerous mice significantly slowed down tumor growth. The animals survived significantly longer and in one quarter of animals the tumors even regressed completely. By contrast, NK cells without prior treatment were ineffective.