Exelixis launched its first drug, the oral tyrosine kinase inhibitor Cometriq (cabozantinib), for treating patients with metastatic medullary thyroid cancer (MTC), after US Food and Drug Administration approval on November 29. The agency did not require a risk evaluation and mitigation strategy for Cometriq, in contrast with London–based AstraZeneca's rival kinase inhibitor Caprelsa (vandetanib), the only other drug approved to treat the rare disease. In a phase 3 study, Cometriq extended progression-free survival for patients to 11.2 months compared with 4 months on placebo. The S. San Francisco, California–based biotech estimates an eligible patient population of 500–700 per year in the US, resulting in a modest marketing opportunity for Cometriq, whose monthly price is $9,900. Exelixis is also studying Cometriq in prostate cancer, a much larger but also crowded market. The two phase 3 trials in prostate cancer, whose data are not expected before 2014, are testing the drug in late-stage, castration-resistant patients who have already progressed on other therapies. Eric Schmidt, an analyst at Cowen and Co., estimates that if Cometriq is able to demonstrate a meaningful survival benefit in prostate cancer, it could garner peak global sales in this indication of $300–500 million.