Researchers explore novel therapeutic approach for thyroid cancer

Some forms of differentiated thyroid cancer (DTC) respond to treatment with radioactive iodine, which is taken up by the thyroid gland, destroying the cancerous cells. However patients with two forms of thyroid cancer, radioiodine-refractory DTC and anaplastic thyroid cancer (ATC), do not benefit from radioiodine therapy, and other treatment options are limited.

Christine Spitzweg, MD, and colleagues from Ludwig-Maximilians-University, Munich, Germany, are exploring a novel therapeutic approach intended to modify the genetic make-up of radioiodine-refractory forms of thyroid cancer to make them more susceptible to the anti-cancer effects of radioiodine therapy. Using a non-viral gene delivery system based on nanoparticle vectors, the researchers are able to introduce the gene for the sodium iodide symporter (NIS) into radioiodine-refractory tumor cells, enhancing their uptake of therapeutic radioiodine.

The vectors contain the NIS gene, a protective polymer, and a synthetic peptide that targets the particle to an epidermal growth factor receptor (EGFR) present at varying levels on the surface of thyroid tumor cells. The researchers mixed the thyroid tumor cells with the nanoparticles. In a parallel experiment, the researchers created a similar nanoparticle complex that lacked the EGFR-specific targeting peptide.

According to data presented today at the 81st Annual Meeting of the American Thyroid Association, tumor cell lines containing higher levels of EGFR incorporated more of the nanoparticle complexes. The tumor cell lines that exhibited the most efficient nanoparticle transduction had a 7-10 fold increase in iodide uptake when the nanoparticles contained the EGFR targeting peptide compared to experiments using the complexes lacking the EGFR targeting peptide.

Preliminary tests of this therapeutic approach in mice indicate that a tumor-selective gene delivery strategy can enhance radioiodine uptake by refractory DTC and ATC tumors.