9 October 2018 - - US-based biotechnology company Exelixis, Inc. (NASDAQ: EXEL) has initiated a phase 3 pivotal trial (COSMIC-311) of single-agent cabozantinib in patients with radioiodine-refractory differentiated thyroid cancer who have progressed after up to two prior vascular endothelial growth factor receptor (VEGFR)-targeted therapies, the company said.

The co-primary endpoints for the trial are progression-free survival and objective response rate.

COSMIC-311 is a multicenter, randomised, double-blind, placebo-controlled phase 3 pivotal trial that aims to enroll approximately 300 patients at approximately 150 sites globally.

Patients will be randomised in a 2: 1 ratio to receive either cabozantinib 60 mg or placebo once daily.

Thyroid cancer is commonly diagnosed at a younger age than most other adult cancers and is the most rapidly increasing cancer in the US, tripling in incidence in the past three decades.

Approximately 54,000 new cases of thyroid cancer will be diagnosed in the US in 2018.

Nearly three out of four of these cases will be in women.

Cancerous thyroid tumors include differentiated, medullary and anaplastic forms.

Differentiated thyroid tumors, which make up about 90 % of all thyroid cancers, are typically treated with surgery followed by ablation of the remaining thyroid with radioiodine.

Approximately 5 to 15 % of differentiated thyroid tumors are resistant to radioiodine treatment.

For these patients, life expectancy is only three to six years from the time metastatic lesions are detected.

Cabometyx tablets are approved in the United States for the treatment of patients with advanced RCC. Cabometyx tablets are also approved in: the European Union, Norway, Iceland, Australia, Switzerland and South Korea for the treatment of advanced RCC in adults who have received prior VEGF-targeted therapy; in the European Union for previously untreated intermediate- or poor-risk advanced RCC; and in Canada for adult patients with advanced RCC who have received prior VEGF targeted therapy.

In March 2017, the FDA granted orphan drug designation to cabozantinib for the treatment of advanced HCC. In May 2018, the FDA accepted Exelixis' supplemental New Drug Application for Cabometyx as a treatment for patients with previously treated HCC and assigned it a Prescription Drug User Fee Act action date of January 14, 2019.

On March 28, 2018, Ipsen announced that the European Medicines Agency validated its application for a new indication for cabozantinib as a treatment for previously treated advanced HCC in the European Union; on September 20, 2018 the CHMP provided a positive opinion for Cabometyx as a monotherapy for the treatment of HCC in adults who have been previously treated with sorafenib. In 2016, Exelixis granted Ipsen exclusive rights for the commercialisation and further clinical development of cabozantinib outside of the United States and Japan.

In 2017, Exelixis granted exclusive rights to Takeda Pharmaceutical company Ltd. for the commercialization and further clinical development of cabozantinib for all future indications in Japan.

Cabometyx is not indicated for radioiodine-refractory DTC.

Founded in 1994, Exelixis, Inc. (NASDAQ: EXEL) is an oncology-focused biotechnology company that strives to accelerate the discovery, development and commercialization of new medicines for difficult-to-treat cancers.