Stanford researchers accidentally discovered that iron nanoparticles invented for anemia treatment have another use: triggering the immune system’s ability to destroy tumor cells. Iron nanoparticles can activate the immune system to attack cancer cells, according to a study led by researchers at the Stanford University School of Medicine. The nanoparticles, which are commercially available as the injectable iron supplement ferumoxytol, are approved by the Food and Drug Administration (FDA) to treat iron deficiency anemia.
The mouse study found that ferumoxytol prompts immune cells called tumor-associated macrophages to destroy cancer cells, suggesting that the nanoparticles could complement existing cancer treatments.
A mouse study found that ferumoxytol prompts immune cells called tumor-associated macrophages to destroy tumor cells.
“It was really surprising to us that the nanoparticles activated macrophages so that they started to attack cancer cells in mice,” said Heike Daldrup-Link, MD, who is the study’s senior author and an associate professor of radiology at the School of Medicine. “We think this concept should hold in human patients, too.”
The study showed that the iron nanoparticles switch the macrophages back to their cancer-attacking state, as evidenced by tracking the products of the macrophages’ metabolism and examining their patterns of gene expression.
Furthermore, in a mouse model of breast cancer, the researchers demonstrated that the ferumoxytol inhibited tumor growth when given in doses, adjusted for body weight, similar to those approved by the FDA for anemia treatment.
Daldrup-Link’s team conducted an experiment that used three groups of mice: an experimental group that got nanoparticles loaded with chemo, a control group that got nanoparticles without chemo and a control group that got neither. The researchers made the unexpected observation that the growth of the tumors in control animals that got nanoparticles only was suppressed compared with the other controls.
The discovery, described in a paper published online in Nature Nanotechnology, was made by accident while testing whether the nanoparticles could serve as Trojan horses by sneaking chemotherapy into tumors in mice.