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Robert Clarke, PhD, executive director and professor, and Lu Jin, MS, researcher at The Hormel Institute, University of Minnesota, have co-authored a paper recently published in the journal ACS Nano.

The paper, “Iron oxide nanoparticles inhibit tumor progression and suppress lung metastases in mouse models of breast cancer,” details the findings of a study exploring how interactions between immune cells and certain nanoparticles can trigger immune system responses that effectively fight off cancer cells, potentially extending survival.

A continuation of research initiated by Robert Ivkov, PhD, Professor at Johns Hopkins University, the study was a collaboration between researchers at Johns Hopkins University School of Medicine and The Hormel Institute, University of Minnesota.

One of the leading causes of breast cancer mortality is metastasis, or the spread of cancer cells to other parts of the body. Despite major therapeutic advances, the five-year survival rate for patients with metastatic breast cancer remains less than 30%. Whether cancer is able to grow and spread, and how quickly, are highly influenced by the body’s immune responses to cancer cells. The findings of this study suggest a potential new tool that could be used to reawaken immune responses to win battles against cancer cells, limit cancer spread, and extend patient lives.

The researchers found that immune cells that routinely remove nanoparticles from the body may exhibit an “infection-like” response that is triggered by some iron oxide nanoparticles (IONPs). This response also works to inhibit tumor growth and metastasis. In tissue samples that were genetically predisposed to develop metastatic breast cancer, the researchers observed an immune system response effectively fighting off cancer cells and slowing tumor growth, preventing the spread (metastases) of cancer to lung tissue.

After triggering this immune response, tissue samples from preclinical models receiving a placebo treatment went on to develop metastases, while no metastasis was found in any of the preclinical model tissues treated with a single injection of certain iron oxide nanoparticles.

Researchers found:

• Iron presence was crucial in helping to initiate immune response.

• In addition to iron, other qualities of the nanoparticles appear to be just as important in triggering the necessary immune response against cancer cells.

• Only certain IONPs induced immune responses in their host (not all).

The study suggests further research is warranted to determine whether IONP formulations could serve as immune adjuvants to boost patients’ immune responses without requiring uptake by cancer cells, which is currently a lingering challenge in cancer treatment.

“This offers the ability to repurpose relatively safe and non-toxic IONPs as adjuvants to existing therapies to increase host immune responses to tumors and potentially increase overall survival for some patients,”  Clarke said.