To determine whether brachytherapy could be performed without the need for surgical implantation of sealed radioactive "seeds" within a tumor and subsequent device removal, Wenge Liu, M.D., Ph.D., from Duke University in Durham, N.C., and colleagues tested a thermally responsive radioactive peptide polymer solution, composed of radiolabeled elastin-like polypeptide, that self-assembles into radionuclide seeds after intratumoral injection.

The researchers found that the formation of the nontoxic and biodegradable polymer seeds showed prolonged retention in the tumor, with about 85 percent retention of the radionuclide a week after injection. In mice bearing either human head and neck cancers or human prostate cancers, the radioactive polymers elicited a tumor growth delay in 100 percent of tumors, and cured 67 percent of animals after a single injection.

"These results suggest that in situ self-assembly of biodegradable and injectable radionuclide-containing polypeptide seeds could be a promising therapeutic alternative to conventional brachytherapy," Liu and colleagues conclude.

One author has a financial interest in PhaseBio Pharmaceuticals, which has licensed the technology described in the study.

Abstract
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