Background: Thyroid cancer is classified into differentiated (DTC), medullary (MTC), and anaplastic (ATC) types. Lenvatinib (LEN) significantly prolonged progression-free survival (PFS) vs placebo in the phase III SELECT trial of patients (pts) with ¹³¹I-refractory DTC (RR-DTC). Initial results of this phase 2 trial (Study 208) of LEN in RR-DTC, MTC, and ATC were reported with a cutoff date of 15 Jun 2014. Here we report the final results of this study. Methods: This was a single-arm, open-label, phase 2 study conducted in Japan with an updated data cutoff of 9 Jul 2015. Pts received LEN 24 mg/d in 28-d cycles until progressive disease or development of unacceptable toxicity. Primary endpoint was safety; secondary endpoint was efficacy as assessed by PFS, overall survival (OS), overall response rate (ORR), and disease control rate (DCR). Results: 51 Pts, including 25 pts with RR-DTC (previously 23), 9 pts with MTC, and 17 pts with ATC (previously 11) were enrolled. All pts had at least one treatment-emergent adverse event (TEAE). The most common any-grade TEAEs included hypertension (90%), decreased appetite (78%), palmar-plantar erythrodysaesthesia syndrome (77%), fatigue (73%), proteinuria (61%), stomatitis (57%), and diarrhea (55%). Incidences of Grade 3 and 4 TEAEs were similar among subgroups (RR-DTC, 72%; MTC, 100%; ATC, 88%). Of note, only 1 pt discontinued treatment due to a TEAE. There were 4 fatal serious AEs, all considered unrelated to LEN. Tumor shrinkage occurred in most pts, including pts with ATC. Median duration of treatment was 5.5 mos (range, 0.7–33.1) for pts with ATC; 8 received LEN for more than 6 mos. Efficacy parameters are shown in the table below. Conclusions: In this study, LEN showed tumor shrinkage in almost all pts with advanced thyroid cancer, including pts with ATC. Toxicities were manageable with dose modifications. LEN efficacy especially in ATC warrants further investigation. Clinical trial information: NCT01728623

NE, not evaluable. *All partial responses.