New clues about how the ovarian cancer tumor works to evade the body’s immune system could offer new leads for treatment and early diagnosis, Johns Hopkins researchers said.
Researchers found that fluid secretions from ovarian tumors, known as ascites, can suppress a specific immune system cell called natural killer T cells.
The cancer tumors shut down these T cells, which are critical for an immune response, said Dr. Jonathan Schneck, co-investigator of a study being published in today’s issue of the journal Clinical Cancer Research.
“This really allows us to now target a specific cell type which is the first, we think, to not function properly,” Schneck said.
For the study, researchers collected ascites from 25 women with ovarian cancer and tested the samples to see if they blocked the activation of the natural killer T cells.
Researchers found this blocking occurred to a specific protein needed to activate the T cells.
The study shows the first evidence tying a specific T cell to ovarian cancer, and the first evidence in humans about how ascites affect the natural killer T cells, researchers said.
“Other cancers can shed or secrete lipids that can impact the immune response of natural killer T cells, but that has never been shown before for ovarian cancer,” said senior investigator Mathias Oelke, an immunologist and assistant professor at Johns Hopkins in Baltimore.
If researchers can find ways to activate the natural killer T cells, they may slow the spreading cancer, Schneck said.
“We can try to develop immune responses or vaccination protocols that can enhance the [natural killer T cell] activity and use that in treating the early stages of ovarian cancer,” he said.
Ovarian cancer kills more women than any other female reproductive cancer, according to the Centers for Disease Control and Prevention.
This type of cancer is difficult to detect, because women often don’t have symptoms until it is in the late stages. Less than half of women with ovarian cancer survive after five years, according to national cancer data.
More than 20,000 U.S. women were diagnosed with ovarian cancer in 2004, and 14,716 women died from the disease.
The Hopkins researchers’ findings may also aid in diagnosing the disease, Oelke said, but future studies are needed to see how early this can be detected.
Researchers want to determine what exactly is inside the ascites that turns the cells off, he said.
“The next step,” Oelke said, “is to identify the substance in the ascites that causes the inhibition.”
