Cells in our immune system are best known for providing security against external invaders such as bacteria and viruses. These immune cells also guard against internal threats, including cancerous tumors. Different forms of cancer cells and tumors have their own tricks for avoiding detection by the body’s security system altogether or otherwise sabotaging any attempts to muster an immune response. In the case of the most common and difficult-to-treat form of ovarian cancer, this ability to suppress the immune system also makes the cancer resistant to treatments known as immunotherapies that seek to supercharge immune cells.

“Even if you boost the capability of immune cells, a treatment will have limited success if the cells struggle to recognize and react to the tumor,” said David Schlaepfer, Ph.D., a professor in the department of OBGYN and Reproductive Sciences at the University of California San Diego Moores Cancer Center.