Researchers from Stanford Medicine may have found a powerful new way to fight cancer while examining a type of bacteria that lives on each person’s healthy skin. To fight cancer, scientists ran a series of tests by altering the genomes of skin-based microbes and bacteria. This genetically engineered bacterium was applied to mice with cancer, and the results are revolutionary.After the scientists genetically engineered the bacterium, called Staphylococcus epidermidis, to produce a tumor antigen (a tumor-specific protein that can stimulate the immune system), they applied the live bacteria to the hairs of mice with cancer. The resulting immune response was strong enough to kill even Melanoma, an aggressive form of metastatic skin cancer, without causing inflammation.
The results were like “magic”
“It was almost like magic. These mice had very aggressive tumors growing on their sides, and we gave them a gentle treatment, we just took a swab of bacteria and rubbed it into the hair of their heads,” says Michael Fischbach, associate professor of bioengineering. says.Staph epidermidis was chosen for the trial because of their unique ability to trigger the production of powerful immune cells called CD8 T cells, which are known to fight cancer or severe infections among colonizing bacteria. In tests, the genetically modified bacteria was able to elicit an immune response that killed or shrunk cancerous cells even far away from where it was applied topically. Fischbach added: “It was shocking to see these tumors disappear—especially in an area far from where we applied the bacteria. It took us a while to believe that this was happening.”
He says Stanford scientists don’t yet know whether Staph epidermidis will elicit a similarly strong immune response in humans, and it’s worth noting that trials on mice don’t always result in trials in humans. The researchers also replaced the skin cancer antigen with a prostate cancer antigen in their test and found that tumor growth was significantly slowed. The researchers said this shows that genetically modified skin-colonizing bacteria can trigger a potent immune response against other cancers.
15 of 16 tumors disappeared
The researchers used this method on mice with Melanoma, the most aggressive and life-threatening skin cancer. Even when melanoma metastasized to the lungs, the treatment greatly reduced or eliminated the size of the tumors and significantly improved the survival times of the mice. The benefit became even more apparent when the researchers combined the new treatment with a second type of immunotherapy designed to boost T-cell activity called “checkpoint blockade”: 15 of the 16 established tumors disappeared. When the mice were injected with more cancer cells after 30 days, their tumors did not grow. In the later stages of the research, it is aimed to switch to human tests.
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