Several types of metal nanoparticles are capable of converting energy, such as that carried by near-infrared light or an oscillating magnetic field, into heat at a level high enough to kill tumors. Now, a recently completed Phase I clinical trial in patients with recurrent prostate cancer has shown that magnetic nanoparticles can be safely administered to humans and will produce localized tumor-killing temperatures when stimulated by an oscillating magnetic field.
Reporting its work in the International Journal of Hyperthermia, a research team head by Manfred Johannsen, M.D., at the Humboldt University Hospital Cherité in Berlin, Germany, describes the results of a Phase I clinical trial involving 10 patients with locally recurrent prostate cancer who had failed primary therapy. The investigators injected biocompatible magnetic iron oxide nanoparticles directly into the patients' tumors using ultrasound and fluoroscopic imaging to guide the injections. The researchers then used a magnetic field applicator designed specifically for administering thermal anticancer therapy to excite the nanoparticles. Each treatment lasted 1 hour and was repeated weekly for 6 weeks.
Using National Cancer Institute criteria for common toxicities associated with cancer therapy, the researchers determined that there were no dose-limiting toxicities. Patients experienced mild discomfort from internal heating, but this could be managed by cooling the skin. Four patients experienced difficulty urinating after therapy, but this problem resolved within 4 weeks. Measures of quality of life showed no lasting adverse effects resulting from therapy.
Although this study was too small to draw statistically significant conclusions about the efficacy of nanoparticle-enabled thermal therapy, the researchers did note that 8 of 10 patients experienced a decline in prostate specific antigen levels that lasted an average of 4.5 months after therapy. One of the nonresponding patients had suboptimal injection of the magnetic nanoparticles, while the other was found subsequently to have preexisting metastatic disease.
This work is detailed in the paper "Morbidity and quality of life during thermotherapy using magnetic nanoparticles in locally recurrent prostate cancer: Results of a prospective Phase I trial." Investigators at MagForce Nanotechnologies, in Berlin, also participated in this study. An abstract of this paper is available through PubMed. View abstract.