Research published recently in the Journal of Experimental Medicine suggests that targeting macrophages in a new kind of immunotherapy could provide hope for patients with malignant ovarian cancer, which is known to be particularly difficult to diagnose. Because diagnosis remains difficult, only four out of six patients on average are still alive after five years, making effective treatment options all the more imperative.
Researchers from Aarhus University, Denmark have used mice models to show how it is possible to remove macrophage from omental fat in order to slow the spread of ovarian cancer. Omental fat is found in the abdominal cavity close to the intestines where it can act as an energy source for migrating cancer cells that originate in the fallopian tubes.
"This is where the omental fat becomes a kind of host for cells which would otherwise perish, and our research now shows that when tumor cells move into the omental fat, two specific types of immune cells known as macrophages alter character. They develop into the disease's small supporters," says Anders Etzerodt, lead author of the study. Anders Etzerodt is Ph.D. and assistant professor of cancer immunology at the Department of Biomedicine at Aarhus University.
"One of the macrophage types which is already present in the tissue simply begins to help the tumor spread further to the other organs in the abdominal cavity. At the same time, the second type of macrophage, which comes from the bloodstream and is recruited as a reaction to the infiltration of tumor cells into the omental fat, begins to counteract the immune system's attempt to fight the invasive cancer cells. In this way, they help the tumor to grow larger," explains Anders Etzerodt.
Hence, by removing these macrophages is both the affected tumors and the bloodstream, the researchers were able to simultaneously slow the spread of the tumors and shrink their sizes. While they have only tested their findings in mice thus far, they hope to develop a drug for human trials, both for ovarian cancer as well as skin cancer and potentially pancreatic cancer.
Speaking of the team’s findings, Anders Etzerodt comments, "We describe a type of immunotherapy which differs from the immunotherapy that is characterized by supporting the T-cells that kill a tumor, and which has become an established part of modern immunological treatment. What we're doing is also immunotherapy, but it focuses on another part of the immune system. This project is only the third scientific article to describe how macrophages with different origins affect tumor development, and precisely how the macrophages that are found to inhibit the immune system's ability to hamper the cancer can be removed. They 'put the brakes on the brake', if you will," he explains.