Lenvatinib enhances the antitumor effects of paclitaxel in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is a rare malignancy and has a very poor prognosis due to its aggressive behavior and resistance to treatment. No effective treatment modalities are currently available. Lenvatinib has shown encouraging results in the patients with radioiodine-refractory differentiated thyroid cancer (DTC); however, lenvatinib monotherapy has a relatively low efficacy against ATC. In this study, we assessed the antitumor effects of a combination of lenvatinib and microtubule inhibitor paclitaxel in ATC cells in vitro and in vivo. Our data showed that lenvatinib monotherapy was less effective than paclitaxel monotherapy in ATC cell lines and xenografts. The addition of lenvatinib to paclitaxel synergistically inhibited colony formation and tumor growth in nude mice, and induced G2/M phase cell cycle arrest and cell apoptosis as compared to lenvatinib or paclitaxel monotherapy. Taken together, this is the first study to suggest that lenvatinib/paclitaxel combination may be a promising candidate therapeutic strategy for ATC.