Iron nanoparticles activated tumour-associated macrophages in the immune systems of mice with cancer, causing their bodies to start fighting the disease, according to a recent study.

The anaemia drug ferumoxytol was found in a study with mice to complement chemotherapy for cancer treatment, and even had an effect on its own, researchers at Stanford University report in a study published in the journal Nature Nanotechnology.

In healthy people, macrophages detect and eat tumour cells, but as tumours grow larger they hijack the macrophages to force them to secrete factors promoting cancer growth rather than working against it.

While nanoparticles have been used to assist or bolster the effect of cancer treatment, researchers at Stanford wanted to test the effects of nanoparticles alone for treating cancer.

"In many studies, researchers just consider nanoparticles as drug vehicles," Dr. Heike Daldrup-Link an associate professor of radiology at Stanford University and senior author of the study, said in a press release. "But they may have hidden intrinsic effects that we won't appreciate unless we look at the nanoparticles themselves."

For the study, researchers experimented with three groups of mice: One received nanoparticles loaded with chemotherapy, one received nanoparticles without chemotherapy and a third received neither treatment.

The researchers found the growth of tumours was suppressed in both groups receiving nanoparticles, but not the untreated group.

To test the effects of nanoparticles alone, the researchers found that in lab tests of cultured cancer cells, those with macrophages reacted to the treatment: Macrophages returned to their cancer-attacking stance, rather than assisting growth of the disease.

"It was really surprising to us that the nanoparticles activated macrophages so that they started to attack cancer cells in mice," Daldrup-Link said. "We think this concept should hold in human patients, too."

Because ferumoxytol is already approved by the FDA for use with anaemia patients, it will be easier for researchers to start testing its use with humans.

Already, they think ideal uses could be for patients between rounds of chemotherapy or in patients whose tumours cannot be completely removed during surgery.

Source: Nature Nanotechnology