Exelixis says cabozantinib study showed 'encouraging' efficacy
Exelixis announced results from a phase 2 investigator-sponsored trial of cabozantinib for the first-line treatment of metastatic radioiodine-refractory differentiated thyroid carcinoma. The results were the subject of a news briefing that took place earlier today and will be presented during an oral session on February 16 starting at 1:30 p.m. MT at the 2018 Multidisciplinary Head and Neck Cancers Symposium, which is being held in Scottsdale, Arizona, February 15-17, 2018. Patients with metastatic, RAI-refractory DTC were enrolled in this single-arm, open-label trial, and were administered oral cabozantinib 60 mg once daily. The primary endpoint of the trial is objective response rate. Among the 35 patients who were evaluable for response, partial response was achieved by 54 percent of patients, and stable disease was reported in 43 percent of patients per RECIST 1.1. All but one evaluated patient experienced a decrease in tumor target lesions. Secondary endpoints of the trial include progression-free survival, time to progression, duration of response and clinical benefit rate defined as the number of patients achieving an objective response or stable disease for at least 6 months. The CBR at six months was 80 percent. With a median follow up for the study of 35 weeks the median PFS has not been reached. The median TTP among those patients who progressed was 35 weeks. "While many patients with differentiated thyroid cancer can be treated successfully with radioiodine, there are very few options for those patients whose tumors have become resistant to treatment," said Marcia Brose, M.D., Ph.D., Associate Professor of Otorhinolaryngology: Head and Neck Surgery and Director of the Center for Rare Cancers at the Abramson Cancer Center of the University of Pennsylvania, and principal investigator of the trial. "These findings suggest that cabozantinib, which showed encouraging efficacy and a manageable safety profile in this phase 2 trial, may be a promising treatment option for this patient population and warrants further evaluation."