Phase III Study Shows Exelixis’ Cabozantinib Nearly Triples PFS in Metastatic Medullary Thyroid Cancer

Exelixis reported additional positive data from a Phase III pivotal trial evaluating cabozantinib in the treatment of progressive, unresectable, and locally advanced or metastatic medullary thyroid cancer (MTC). The firm completed its cabozantinib NDA submission to FDA for the MTC indication at the end of May.

Carried out under Special Protocol Assessment with FDA, the placebo-controlled Exam study involved 330 patients. The study met its primary endpoint in terms of increasing median progression free survival (PFS) from 4 months (for placebo-treated patients) to 11.2 months for patients in the capozantinib arm. Cabozantinib therapy was associated with an estimated PFS at one year of 47.3%, compared with 7.2% for placebo. The overall response rate was 28% for cabozantinib-treated patients, and 0% among placebo-treated patients. Data for overall survival isn’t yet mature, Exelixis reports.

Cabozantinib is a targeted therapy that inhibits MET, VEGFR2, and RET, and has demonstrated tumoricidal, antimetastatic, and antiangiogenic effects. “Beyond MTC, we are also excited about the encouraging interim cabozantinib data that has been generated in a variety of other tumor indications, including hepatocellular carcinoma, renal cell carcinoma, and castration-resistant prostate cancer,” comments Michael M. Morrissee, Ph.D., president and CEO at Exelixis. “In particular, the prostate cancer data formed the basis for advancing cabozantinib into two recently initiated Phase III pivotal trials, Comet-1 and Comet-2."