Previous research has linked neutrophils to cancer metastasis, but a new study published in Science Translational Medicine may have uncovered more information about why this happens.
The study’s researchers found that neutrophil extracellular traps (NETs), which the immune system normally uses to kill harmful pathogens, may help metastatic cancer cells form new tumors in other parts of the body.

The researchers hope that the findings may one day be used to develop new targeted therapies for cancer. Current targeted treatments have focused on other immune cells such as T cells and macrophages, but so far no cancer treatments have targeted neutrophils.

NETs are involved in a treatment currently available for cystic fibrosis, however, called DNase I. The treatment administers an inhaled enzyme that dissolves the NETs that can cause mucus buildup in the lungs of patients with cystic fibrosis.

The researchers tested the NET treatment in mouse models, using a modified form of DNase I that was bound to nanoparticles, allowing the drug to be active in the body long enough to reach metastatic tumors. In their study, three of the nine mice injected with metastatic breast cancer cells who received the modified DNase I had no detectable metastases. All of the mice in the treatment arm had fewer and smaller metastases than those who received control nanoparticles without DNase I.

Researchers cautioned that the findings are still early and many questions remain unanswered about neutrophils’ role in cancer. They said that the relationship is a fine balance, because other research has shown that the cells promote tumor growth in some situations and hinder it in others.

Additional studies are needed to understand exactly how NETs are involved in metastasis and the best way to formulate treatments.

Park, J., Wysocki, R.W., Amoozgar, Z., Maiorino, L., Fein, M.R., Jorns, J., . . . Egeblad, M. (2016). Cancer cells induce metastasis-supporting neutrophil extracellular DNA traps. Science Translational Medicine, 8, 361ra138. doi:10.1126/scitranslmed.aag1711