Phase II Trial of Sorafenib in Patients with Advanced Anaplastic Carcinoma of the Thyroid

Background: Anaplastic thyroid cancer (ATC) is a rare but highly aggressive malignancy with a median survival of 3-5 months. The BRAF oncogene is mutated to its active form in up to 24% of ATC cases. Sorafenib is a tyrosine kinase inhibitor that acts on the RAF-1 serine/threonine kinase. In preclinical mouse models, sorafenib inhibits the growth of ATC xenografts and improves survival. No study of sorafenib in ATC has been conducted. We conducted a multi-institutional phase II trial of sorafenib in patients with ATC who had failed up to two previous therapies. Methods: The primary endpoint of the trial was the Response Evaluation Criteria In Solid Tumors (RECIST)-defined imaging response rate. Twenty patients with ATC were treated with sorafenib 400 mg twice daily. Results: Two of the 20 patients had a partial response (10%) and an additional 5 of 20 (25%) had stable disease. The duration of response in the two responders was 10 and 27 months, respectively. For the patients with stable disease, the median duration was 4 months (range 3-11 months). The overall median progression-free survival was 1.9 months with a median and a 1-year survival of 3.9 months and 20%, respectively. Toxicity was manageable and as previously described for sorafenib, including hypertension and skin rash. Conclusion: Sorafenib has activity in ATC, but at a low frequency and similar to our previous experience with fosbretabulin. One patient with a response had previously progressed on fosbretabulin. Toxicities were both predictable and manageable.