Combining Drugs May Improve Ovarian Cancer Survival

Researchers at Johns Hopkins have found that combination therapy improved ovarian cancer survival in mice studies, prolonging survival and reducing tumor burden.

They performed a mouse experiment in which mice with ovarian cancer were treated with combination therapy using two otherwise ineffective drugs. They found that a careful pairing of ovarian cancer drugs improved the survival rate of their experimental mice.

Two initially ineffective ovarian cancer drugs turned out to be successful

What the researchers did was take two ineffective therapies, a gene therapy, and an immunotherapy approach, and use them together. The combined use of these drugs led to a huge improvement in the body's ability to fight off the ovarian cancer cells. Senior author Dr. Cynthia Zahnow explains that when used together, the immune system gets stimulated and does a better job of attacking the malignant cells.

The combination involves a drug that targets the immune system paired with a drug that controls gene expression

The combination pairs an immunotherapy drug with one that targets gene silencing. Immunotherapy drugs, which have been used successfully to treat other cancers like melanoma and lung cancer, work by helping immune cells recognize cancer cells so they can do a better job attacking them and killing them off. Gene-silencing drugs, on the other hand, work by adding chemical tags known as methyl groups to DNA, marking genes for storage by proteins known as histones. Both of these drugs have been unsuccessful when used alone to treat ovarian cancer, but Zahnow has seen promising results in her mice when they are used together.

Mouse models are helpful for scientists to study human diseases

Zahnow's mice are good representations of advanced disease in humans. Despite the obvious physical differences between mice and humans, it turns out that we also share a lot of biological similarities that can be harnessed for medical research. Mouse models are widely used in science to help us understand physiologic processes of various human diseases. Zahnow and her colleagues have been injecting mice stomachs with ovarian cancer cells to mimic advanced cancer. When injected, these cells spread far and wide in the body, producing hundreds of little tumors similar to what happens in metastatic ovarian cancer. The mice often develop ascites, which is a condition where fluid collects into the abdominal cavity. In this fluid, there are lots of cancer and immune cells. Researchers are easily able to tap into this fluid to perform studies on the animal's immune response to these cancerous cells.

Previous work also proved to be successful

Zahnow's team has had a long track record working with ovarian cancer. They were inspired to investigate combination therapy because their previous work found that epigenetic drugs can actually activate genes that turn on the immune system. These drugs work by modifying the chemical structure of DNA, resulting in changes of gene expression and ultimately, cell properties. They wondered if they could harness this effect by strengthening the activated immune system by using immunotherapy drugs.

Read on to learn more about this important discovery and what it might mean for the future of ovarian cancer survival.