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Posted: Oct 04, 2016
New study shows that iron oxide nanoparticles inhibit tumour growth
(Nanowerk Spotlight) The intravenous iron-replacement product ferumoxytol and other iron oxide nanoparticles are being used for treating iron deficiency, as contrast agents for magnetic resonance imaging, and as drug carriers.
In a new study, for the first time, researchers have shown an intrinsic therapeutic effect of ferumoxytol on the growth of early mammary cancers and lung cancer metastases in liver and lungs. They showed that ferumoxytol can activate the immune system to attack cancer cells.
"Our data have broad implications for diagnostic and therapeutic nanoparticle applications," says Morteza Mahmoudi, an assistant professor at Tehran University of Medical Sciences, who heads the Laboratory of Nano-Bio Interactions, and co-author of the paper. "Since ferumoxytol is FDA-approved for intravenous treatment of iron deficiency, it could be applied 'off label' to protect the liver in patients from metastatic seeds and potentiate TAMs-modulating cancer immunotherapies."
Previous studies have described the use of iron oxide nanoparticles for targeted delivery of therapeutics (see for instance our previous Nanowerk Spotlight: "Smart cancer nanotheranostics"). In these studies, the nanoparticles served as carriers of therapeutic drugs to the tumor microenvironment.
Conversely, in this new study, the scientists observed an intrinsic therapeutic effect of iron oxide nanoparticles themselves.
"Our proposed approach to suppress liver metastases by repetitive systemic ferumoxytol administrations should be achievable without significant impact on iron load or liver toxicity," notes Zanganeh.
He adds that, due to the large surface area and chemically defined surface structure, iron oxide nanoparticles such as ferumoxytol can be conjugated or functionalized to numerous ancillary molecules to further amplify the desired immune-modulating properties.
The scientists explain that ferumoxytol could be locally delivered to unresectable tumors via interventional procedures, to micrometastases in confined spaces – e.g. peritoneal seeds. Or to tumor resection margins at the end of a tumor surgery with positive resection margins, in order to induce a pro-inflammatory reaction against cancer cells and suppress tumor growth in the interval between a tumor surgery and initiation of postsurgical chemotherapy or irradiation.
On the other hand, patients with primary tumors that typically metastasize to the liver could receive protective ferumoxytol medications to prevent early metastatic seeds.
In the next stage of their study, the researchers will be more focused on the evaluations of nanoparticle-drug combinations. Potential clinical applications of ferumoxytol-mediated pro-inflammatory immune responses could entail potentiating the efficacy of other M1-activating cancer immunotherapies, such as anti-CD47 mAbs or antibodies blocking IL-4 or IL-13 signaling.