“Build your enemy a golden bridge to retreat across” is a piece of advice offered by Sun Tzu in his ancient military treatise, The Art of War. It turns out that cancerous growths adopt this strategy in their battle against the immune system. In a new study being published in Cell Reports, researchers from Prof. Idit Shachar’s laboratory at the Weizmann Institute of Science have discovered that a certain type of aggressive breast cancer prompts nearby immune cells to build “molecular bridges” between themselves, which causes these cells to refrain from attacking the cancer and leads to immune suppression. An antibody treatment that blocks the building of these bridges was shown to restore the immune system’s ability to attack with force, inhibiting the cancer’s progression in a mouse model.
In the past, cancer treatment focused on destroying the malignant cells by, for example, using radiation treatment or chemotherapy. In recent decades, however, it has become evident that a tumor’s development depends on the communication between the cancer and the nearby noncancerous cells. In an earlier study, researchers from Shachar’s lab in Weizmann’s Systems Immunology Department showed that blood cancer cells create “molecular bridges” with nearby support cells in order to survive and proliferate – otherwise they die within a matter of days. The researchers identified a protein, CD84 (SLAMF5), that is used to construct these bridges: When this protein is present on the surface of a specific immune cell, it can bind to a similar protein on a different cell, creating an intercellular