Lenvatinib also inhibited the phosphorylation of RET with the activated mutation C634W in TT cells. These data demonstrate that lenvatinib provides antitumor activity mainly via angiogenesis inhibition but also inhibits FGFR and RET signaling pathway in preclinical human thyroid cancer models....These data demonstrate that lenvatinib inhibits the RET signaling pathway that is activated by mutations in RET in vitro and lenvatinib thus may show significant antitumor effects in the human MTC TT xenograft model.