Cancer becomes far more dangerous when it spreads from its original location to other parts of the body. This process, known as metastasis, is responsible for most cancer-related deaths.
When cancer cells break away from the main tumor and travel through the bloodstream or lymph system, they can settle in other organs such as the lungs, liver, or brain. Once these cells begin to grow in new locations, the disease becomes much harder to treat.
Doctors have traditionally focused on controlling or shrinking the primary tumor. Surgery, radiation therapy, and chemotherapy are often used to remove or destroy the main tumor in the body.
However, even when the original tumor is successfully treated, a small number of cancer cells may have already spread elsewhere. These cells can remain hidden and later grow into new tumors in distant organs.
Because of this challenge, scientists are searching for ways to stop metastasis before it begins. A new study from researchers at the Dana-Farber Cancer Institute has uncovered a possible strategy that may help the immune system destroy cancer cells that have spread through the body.
The research focused on a particularly aggressive form of breast cancer known as triple-negative breast cancer, often shortened to TNBC.
This type of breast cancer is called “triple negative” because the cancer cells do not carry three common receptors that many breast cancer treatments target. As a result, TNBC is more difficult to treat and tends to spread more quickly than other types of breast cancer.
The study was led by Dr. Judith Agudo, a scientist at Dana-Farber. Her team wanted to understand why some cancer cells are able to escape the body’s natural immune defenses when they spread to other organs.
Normally, the immune system acts as the body’s defense force. Immune cells patrol the body looking for abnormal cells, including cancer cells. When they find them, they attempt to destroy them. However, cancer cells can sometimes develop ways to hide from the immune system or resist being attacked.
To investigate how this happens, the researchers created a new experimental tool called “Jedi.” This technology allowed them to identify cancer cells that had spread from the original tumor and survived in distant organs in animal models. By studying these surviving cells, the team hoped to discover what allowed them to evade immune attack.
Using advanced genetic analysis techniques, including RNA sequencing and epigenetic tools, the scientists examined the biological activity of these metastatic cancer cells. They discovered that some of the cancer cells activated a specific biological pathway involving a protein known as the glucocorticoid receptor.
The glucocorticoid receptor plays an important role in how the body responds to stress hormones. In the metastatic cancer cells, activation of this receptor appeared to protect the tumor cells from being destroyed by immune cells.
In other words, the receptor helped the cancer cells survive in their new environment even when the immune system tried to eliminate them.
After making this discovery, the researchers looked for ways to block this protective effect. They found that a drug called mifepristone could inhibit the glucocorticoid receptor.
Mifepristone is already approved by the U.S. Food and Drug Administration for other medical uses, which makes it especially interesting for researchers exploring new treatments.
When the scientists treated animal models with mifepristone, the cancer cells that had spread to other organs became more vulnerable to immune attack. The immune system was better able to recognize and destroy these cells. As a result, the number of tiny metastatic tumors, known as micro-metastases, was significantly reduced.
The researchers also tested whether combining this treatment with immunotherapy could produce even better results. Immunotherapy drugs known as immune checkpoint inhibitors help boost the immune system’s ability to fight cancer. In this study, the team used an anti-PD1 checkpoint inhibitor along with mifepristone.
The combination produced stronger effects. The number of metastatic tumors decreased further, and survival improved in the animal models. This suggests that blocking the glucocorticoid receptor may make immunotherapy more effective in preventing the spread of cancer.
Although these findings are promising, the researchers emphasize that the work has so far only been tested in mice. More research will be needed to determine whether the same strategy works in human patients.
However, there are encouraging signs. Previous studies have shown that the glucocorticoid receptor is active in human samples of triple-negative breast cancer. Higher activity of this receptor has been linked with increased metastasis and poorer outcomes in patients. This supports the idea that the same biological mechanism may also be present in people.
If future clinical trials confirm these results, the approach could represent a major shift in how cancer is treated. Instead of focusing only on shrinking existing tumors, doctors might be able to prevent metastasis from occurring in the first place.
This could be especially important for many types of solid tumors, including breast, prostate, and colon cancer. In these diseases, the risk of death rises dramatically once the cancer spreads to other organs. Preventing metastasis could therefore save many lives.
The research was published in the journal Nature and highlights the potential of using the body’s own immune system to stop cancer cells before they form new tumors.
When reviewing the findings, the study presents an exciting new strategy for cancer treatment. By identifying how metastatic tumor cells protect themselves from immune attack, scientists have uncovered a possible weakness that can be targeted with existing drugs.
However, because the research is based on animal models, careful human studies will be necessary before the treatment can be used in clinical practice. If future trials confirm its effectiveness, this strategy could lead to new therapies that prevent metastasis and greatly improve survival for patients with aggressive cancers.
If you care about breast cancer, please read studies about how eating patterns help ward off breast cancer, and soy and plant compounds may prevent breast cancer recurrence.
For more health information, please see recent studies about how your grocery list can help guard against cancer, and a simple way to fight aging and cancer.
The study is published in Nature.
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