A study published in the journal Scientific Reports shows that Claudin-4, a protein that increases in ovarian cancer, may be the culprit behind the cancer’s resistance, helping tumors both survive and hide from the body’s natural defense, the immune system.

The study was led by UTEP postdoctoral researcher Fabian R. Villagomez, Ph.D., and Benjamin G. Bitler, Ph.D., of the University of Colorado Anschutz.

The research team studied tumors growing in animal models that have an immune system similar to humans. Targeting Claudin-4 helped the immune system better find and attack the tumors, making the cancer more vulnerable to treatment.