Multicenter Randomized Double-Blind Phase III Trial of Donafenib in Progressive Radioactive Iodine-Refractory Differentiated Thyroid Cancer.

[PURPOSE] The phase II/III study of donafenib was initiated when there was no available treatment indicated for Chinese patients with progressive radioactive iodine-refractory differentiated thyroid cancer (RAIR-DTC). Donafenib, an oral tyrosine kinase inhibitor (TKI), showed good efficacy and tolerability in the phase II study. We aimed to further evaluate the antitumor activity and safety of donafenib in Chinese patients with RAIR-DTC.

[PATIENTS AND METHODS] This multicenter, double-blind, placebo-controlled, phase III study enrolled 191 patients with progressive RAIR-DTC and randomized in a ratio of 2:1 to donafenib (300 mg twice daily, n = 128) or matched placebo (n = 63). An open-label donafenib treatment period was allowed upon disease progression. The primary endpoint was progression-free survival (PFS) assessed by the independent review committee. The second endpoints include objective response rate (ORR), disease control rate (DCR), safety, etc.

[RESULTS] Donafenib demonstrated prolonged median PFS over placebo [12.9 vs. 6.4 months; hazard ratio (HR), 0.39; 95% confidence interval (CI), 0.25-0.61; P < 0.0001] in Chinese patients with RAIR-DTC. Improved ORR (23.3% vs. 1.7%; P = 0.0002) and DCR (93.3% vs. 79.3%; P = 0.0044) were observed in the donafenib group over placebo. For donafenib, the most common grade ≥ 3 treatment-related adverse events (AE) included hypertension (13.3%) and hand-foot syndrome (12.5%), 42.2% underwent dose reduction or interruption, and 6.3% experienced discontinuation.

[CONCLUSIONS] Donafenib was well-tolerated and demonstrated clinical benefit in terms of improved PFS, ORR, and DCR in patients with RAIR-DTC. The results suggest that donafenib could be a new treatment option for patients with RAIR-DTC.