Green-stained macrophages engulf red-labeled cancer cells after treatment with PSEs. The red signal inside the macrophages shows that they have taken up cancer cells. Credit: Valerio Sabatino, University of Basel
Researchers from Cambridge and Basel have developed small molecules that could make cancer immunotherapies more effective. They work in two ways: they prompt macrophages to engulf cancer cells and alter the surrounding tissue, reducing its ability to suppress immune attacks on the tumor.
"Cold tumors" is a term experts use for cancers that shield themselves so effectively from the immune system that therapies often have little effect. New therapeutic approaches are therefore needed.
Researchers are increasingly turning their attention to the tissue surrounding tumors. Cancer reshapes this environment to its own advantage. One molecule, PD-L1, plays a key role: It acts like a stop signal for the immune system's T cells, preventing them from attacking the tumor.
"But PD-L1 is found not only on the cancer cells themselves but also on certain immune cells in the tumor microenvironment known as macrophages or phagocytic cells," says professor Gregor Hutter of the University of Basel and University Hospital Basel. "Cancer effectively co-opts these immune cells to suppress T-cell responses."
