Exelixis declares results from Phase 2 IST of Cabozantinib treating RAI-DTC

In a bid to treat metastatic radioiodine (RAI)-refractory differentiated thyroid carcinoma (DTC), Exelixis declared results from a Phase 2 Investigator-sponsored trial of cabozantinib.

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 (n=19), and stable disease was reported in 43 percent of patients (n=15) 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 (PFS), time to progression (TTP), duration of response (DOR) and clinical benefit rate (CBR) defined as the number of patients achieving an objective response or stable disease for at least 6 months.

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 claimed “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.”

Gisela Schwab, M.D., President, Product Development and Medical Affairs and Chief Medical Officer, Exelixis said “Based on these promising results and data from other studies of cabozantinib in previously treated DTC, Exelixis plans to initiate a pivotal phase 3 study with cabozantinib in patients with advanced DTC later this year.”

The IST is being conducted by the Center for Rare Cancers and Personalized Therapy at the Abramson Cancer Center of the University of Pennsylvania. Enrollment for the trial was completed in August 2017. Dr. Marcia Brose, Associate Professor of Otorhinolaryngology: Head and Neck Surgery, Perelman School of Medicine of the University of Pennsylvania is the principal investigator. The median age of patients is 65 years (range 45 to 84) and 17 patients (49 percent) are male. Of the patients in the trial, 23 (66 percent) had papillary thyroid cancer, 3 (9 percent) had follicular (Hürthle cell) thyroid cancer and 9 (26 percent) had poorly differentiated histology.