Thyroid cancer is classified into differentiated (DTC), medullary (MTC), and anaplastic (ATC) types. Lenvatinib prolonged progression-free survival (PFS) versus placebo in the phase 3 SELECT trial for 131I-refractory DTC (RR-DTC). Initial results of this phase 2 trial in RR-DTC, MTC, and ATC were previously reported; final results are reported here.
This single-arm, open-label study was conducted in Japan (updated data cutoff: 9 July 2015). Patients received lenvatinib (24 mg/d, 28-d cycles) until progressive disease or development of unacceptable toxicity. Primary endpoint was safety; secondary endpoints included PFS, overall survival (OS), overall response rate (ORR), and disease control rate (DCR).
Fifty-one patients (25 with RR-DTC [previously 23], 9 with MTC, and 17 with ATC [previously 11]) enrolled. All had ≥1 treatment-emergent adverse event (TEAE). Common TEAEs included hypertension (90%), decreased appetite (78%), palmar-plantar erythrodysesthesia syndrome (77%), fatigue (73%), proteinuria (61%), stomatitis (57%), and diarrhea (55%). Incidences of grade 3/4 TEAEs were similar among subgroups (RR-DTC, 72%; MTC, 100%; ATC, 88%). Only 1 patient discontinued due to a TEAE. There were 4 fatal AEs (none treatment-related). Most patients showed tumor shrinkage. Median duration of treatment was 5.5 months (range, 0.7–33.1) for patients with ATC; 8 received lenvatinib for >6 months. Median PFS (95% CI) was 25.8 (18.4–not evaluable [NE]), 9.2 (1.8–NE) and 7.4 (1.7–12.9) months for RR-DTC, MTC, and ATC, respectively. Median OS (95% CI) was 31.8 (31.8–NE), 12.1 (3.8–NE), and 10.6 (3.8–19.8) months for RR-DTC, MTC, and ATC, respectively. ORR was 68% for RR-DTC, 22% for MTC and 24% for ATC (all partial responses). DCR was 100% for RR-DTC and MTC and 71% for ATC.
Lenvatinib showed tumor shrinkage in most patients, including those with ATC. Toxicities were manageable with dose modifications. Lenvatinib efficacy, especially in ATC, warrants further investigation.