Potential synergistic effects of sorafenib and CP-31398 for treating anaplastic thyroid cancer with p53 mutations.

Thyroid cancer is the most commonly diagnosed endocrine cancer. Anaplastic thyroid cancer (ATC) is the most aggressive type of thyroid cancer and has a poor prognosis. Loss of p53 function has been reported to lead to poorly differentiated thyroid tumors; therefore, mutant p53 protein can be considered a crucial therapeutic target in patients with ATC. Sorafenib, a multi-kinase inhibitor, has been approved for the treatment of metastatic and differentiated thyroid cancer. Combined targeted therapy, including sorafenib, may be clinically significant for patients with ATC harboring p53 mutations. In the present study, CP-31398, a p53-restoring agent, was used to improve the therapeutic efficacy of sorafenib in SW579 cells, an ATC cell line harboring p53 mutations. The molecular function of CP-31398 was evaluated using western blot analysis and a luciferase reporter assay. The decreased viability of SW579 cells, following CP-31398 treatment, was augmented by sorafenib, and CP-31398 enhanced the antimitogenic effect of sorafenib; thus, sorafenib and CP-31398 synergistically inhibited the growth of SW579 cells. These results indicate a potential clinical application of CP-31398 for patients with ATC harboring p53 abnormalities, since these individuals generally respond poorly to sorafenib alone.