LAKE BUENA VISTA, FLA. – Outcomes in patients with radioiodine-refractory differentiated thyroid cancer treated with lenvatinib did not differ based on metastatic site, according to a subanalysis of data from the phase 3, randomized, double-blind SELECT trial.
The overall response rate in 257 patients from that trial (the Study of Lenvatinib in Differentiated Cancer of the Thyroid) who had one or more metastatic sites of radioiodine-refractory differentiated thyroid cancer (RR-DTC) was more than 50% (vs. 1.6% or less in 131 treated with placebo) regardless of the number of metastatic sites at baseline and regardless of the site, Dr. Mouhammed Amir Habra reported in a poster at the International Thyroid Congress.
Further, the overall response rate did not differ significantly between those with zero to one vs. two or more metastatic sites, said Dr. Habra of the University of Texas MD Anderson Cancer Center, Houston.
For common sites of metastasis, including bone, liver, lungs, and lymph nodes, median progression-free survival (PFS) was significantly prolonged with lenvatinib vs. placebo. The median was not estimable for those with one or no metastatic sites who were treated with lenvatinib and was 3.7 months for those who received placebo. The corresponding values for those with two or more metastatic sites were 15.9 vs. 3.6 months.
An exception was in those with brain metastasis, who had PFS of 8.8 vs. 3.7 months with lenvatinib vs. placebo, respectively, but this subgroup included only 16 patients, Dr. Habra noted.
Time to first objective response was also similar between metastatic groups (1.9, 3.6, 3.5, and 2 months in those with brain, bone, liver, and lung metastases at baseline, respectively). The median duration of objective response was 6.9 months in those with brain metastases and 9.2 months in those with liver metastases at baseline. The duration of objective response was not reached in those with bone and lung metastases at baseline.
In the pivotal SELECT trial, the oral multikinase inhibitor lenvatinib significantly prolonged PFS in patients with RR-DTC vs. placebo (median PFS of 18.3 vs. 3.6 months).
“These [current] findings suggest a treatment benefit vs. placebo with lenvatinib regardless of number and type of metastatic sites at baseline,” Dr. Habra concluded at the meeting held by the American Thyroid Association, Asia-Oceania Thyroid Association, European Thyroid Association, and Latin American Thyroid Society.
The study was funded by Eisai, and additional support was provided by Oxford PharmaGenesis.