A phase 3 (COSMIC-311), randomized, double-blind, placebo-controlled study of cabozantinib in patients with radioiodine (RAI)-refractory differentiated thyroid cancer (DTC) who have progressed after prior VEGFR-targeted therapy.

Abstract

TPS6097 Background: Treatment options are limited for patients with RAI-refractory DTC that is resistant to VEGFR-targeted therapy. Cabozantinib inhibits receptor tyrosine kinases including VEGFR2, MET, AXL, and RET, which are implicated in the development of DTC, and has shown clinical activity in early-phase studies of patients with RAI-refractory DTC. This study evaluates the efficacy and safety of cabozantinib in patients with RAI-refractory DTC who have progressed during or after prior VEGFR-targeted therapy. Methods: This is a phase 3, multicenter, randomized, double-blind, placebo-controlled trial (NCT03690388). The co-primary endpoints are progression-free survival and objective response rate evaluated by blinded independent radiology committee (BIRC) per RECIST v 1.1. Additional endpoints include safety, overall survival, quality of life, and changes in relevant biomarker levels (eg, thyroglobulin). Approximately 300 patients will be randomized in a 2:1 ratio to receive either cabozantinib (60 mg QD orally) or placebo. Randomization is stratified by prior treatment with lenvatinib and age (≤ 65 yrs vs > 65 yrs). Eligible patients must have a pathologic diagnosis of DTC and must have been previously treated with or deemed ineligible for treatment with iodine-131 for DTC. Patients must have received lenvatinib or sorafenib for DTC and progressed during or following treatment with a VEGFR inhibitor. Up to 2 prior VEGFR-targeting TKI agents are allowed. Patients randomized to placebo may be eligible for real time on-study crossover to cabozantinib based on BIRC confirmation of disease progression. Unblinded patients randomized to cabozantinib may continue on study treatment if there is clinical benefit per investigator. Key words: Radioiodine-refractory differentiated thyroid cancer, cabozantinib, VEGFR-targeted therapy, trial-in-progress. Clinical trial information: NCT03690388.