Phase 2 clinical trial of sunitinib as adjunctive treatment in patients with advanced differentiated thyroid cancer

Objective: Our objective was to evaluate the efficacy and safety of sunitinib following at least one course of radioactive iodine treatment in patients with advanced differentiated thyroid cancer (DTC). The study endpoints included best response rate (including best objective response rate) and progression-free survival (PFS) per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, measurement of serum thyroglobulin (Tg), and toxicity evaluation. Design and methods: This was a single center, nonrandomized, open-label, phase 2 clinical trial. In total, 23 patients were enrolled and were treated with a starting daily, oral dose of 37.5 mg sunitinib. Patients were evaluated with imaging, laboratory tests, and physical examination periodically per protocol. Results: The mean best response was a decrease of 17.2% (S.D. 22.8) in tumor sum from baseline. Six (26%) patients achieved a partial response (PR), and 13 (57%) had stable disease (SD) for a clinical benefit rate (PRCSD) of 83%. The overall median PFS was 241 days (interquartile limits, 114-518). No statistically significant difference was observed between the medians of the baseline and post-treatment Tg values (P=0.24). The most common adverse events included grades 1 and 2 decreases in blood cell counts (especially leukocytes), diarrhea, fatigue, hand-foot skin reaction, nausea, musculoskeletal pain, and hypertension. Conclusions: These data demonstrate that sunitinib exhibits significant anti-tumor activity in patients with advanced DTC. Since sunitinib was relatively well-tolerated, there is the potential for clinical benefit in these patients, and further investigation of this agent is warranted.