Experimental vaccine reprograms cancer to launch immunotherapy attack

Scientists have developed a new type of cancer vaccine that shows promise in clearing out leukemia in mice. The technique involves reprogramming cancer cells into immune cells so that they can teach the immune system how to fight off the disease.

One of the most common forms of immunotherapy works by removing T cells from a patient, programming them to recognize specific cancer antigens, and setting them loose in the body to hunt down cancers with those antigens. The problem is, this requires a degree of guesswork in figuring out which antigens would be most useful for each patient.

So for the new study, scientists at Stanford Medicine developed a way to teach T cells to recognize a broader swathe of antigens, increasing the chances that a patient’s immune system would successfully attack their cancer. The trick is to convert cancer cells into macrophages, which are a type of antigen-presenting cell (APC) that teaches T cells what to look for.

“We hypothesized that maybe cancer cells reprogrammed into macrophage cells could stimulate T cells because those APCs carry all the antigens of the cancer cells they came from,” said Ravi Majeti, senior author of the study.

To test the idea, the researchers induced leukemia cells in mice to transform into APCs. And sure enough, the mice in the control group successfully cleared out their cancer. Better yet, the vaccine strategy seemed to work longer term to prevent the disease recurring.

And finally, the researchers experimented with cells taken from human patients. Sure enough, APCs derived from human leukemia cells seemed to be successful in teaching T cells from the same patient what to look for. That suggests that the method could eventually be applied to humans, but far more work still needs to be done.

Image source: Steve Fisch, Stanford Medicine.