It turns out that certain cells send signals to the regions where cancer is going to claim territory.

Scientists have used genetic engineering to modify immune cells called myeloid cells in order to target cancer cells that may spread to other organs. They conducted a study on mice and found that the engineered cells were able to shrink tumors and prevent the cancer from spreading. The research, led by scientists at the National Cancer Institute, the Center for Cancer Research, and the National Institutes of Health (NIH) in the US, was published in March 2021.

Metastatic cancer, which is cancer that has spread from its original location, is difficult to treat, says an NIH release. The researchers aimed to prevent cancer from spreading in the first place. They discovered that before cancer spreads, it sends out signals that prepare other parts of the body for its arrival. These prepared sites are called premetastatic niches. 

In the study, the researchers focused on immune cells in the premetastatic niche.

They observed that in the lungs of the mice, where the cancer hadn't yet spread, there were few cancer-killing immune cells but many cells that suppress the immune system. Myeloid cells were particularly abundant in the premetastatic niche and were sending signals that suppressed the cancer-fighting immune cells.

The researchers then genetically engineered the myeloid cells by adding a gene for a signal called interleukin 12 (IL-12). The goal was to activate the immune system in the premetastatic niche. In mice with a type of muscle cancer, the engineered cells produced IL-12, recruited cancer-killing immune cells, and reduced the signals that suppress the immune system.

Mice treated with these engineered cells had less cancer in their lungs, smaller tumors, and lived longer compared to mice treated with non-engineered cells. The combination of the engineered cells with chemotherapy, surgery, or T-cell transfer therapy showed even better results. In some cases, the combination treatment completely eliminated all traces of cancer.

The researchers also found evidence that the combination treatment created a long-lasting immune memory of the cancer, preventing it from coming back. They tested the engineered cells using human cells in the lab and saw similar results.
The team plans to conduct clinical trials to test the safety and effectiveness of these engineered cells in adults, and later in children and adolescents with cancer. They are cautious about potential side effects and want to ensure the treatment is safe.

The researchers believe that the engineered cells, which produce a small amount of IL-12 similar to the body's natural response, can activate the immune system against the cancer without causing toxic effects.

So far, there is no effective treatment to cancer. Yet, if it is discovered early, modern medicine is capable of fighting back cancer, depending on a variety of factors.