Oncology company Exelixis Inc (NASDAQ:EXEL) revealed on Tuesday the admission of the first 100 patients under its phase 3 pivotal COSMIC-311 trial evaluating cabozantinib (CABOMETYX) versus placebo for radioactive iodine-refractory differentiated thyroid cancer.

The company said the phase 3 pivotal trial will evaluate cabozantinib versus placebo in patients with radioactive iodine-refractory differentiated thyroid cancer who have progressed after up to two vascular endothelial growth factor (VEGF) receptor-targeted therapies.

COSMIC-311 is the company's multicentre randomised, double-blind, placebo-controlled phase 3 pivotal trial that aims to enroll 300 patients at 150 sites globally. The patients will be randomized in a 2:1 ratio to receive either cabozantinib 60 mg or placebo once daily.

Additionally, the company expects to announce analysis in the first 100 patients for the co-primary endpoint of objective response rate and an interim analysis of progression-free survival in the second half of 2020. The total enrollment of 300 patients is expected in the second half of 2020.

Cancerous thyroid tumors include differentiated, medullary and anaplastic forms, but differentiated thyroid tumors make up about 90 percent of cases. For these patients, life expectancy is only three to six years from the time metastatic lesions are detected.