A randomized phase II/III trial of a tumor vascular disrupting agent fosbretabulin tromethamine (CA4P) with carboplatin (C) and paclitaxel (P) in anaplastic thyroid cancer (ATC): Final survival analysis for the FACT trial

5502 Background: CA4P, a vascular disrupting agent (VDA), has shown clinical activity as monotherapy in patients with ATC. Results include a durable CR in a phase I trial and a median survival of 4.7 months with 34% of patients alive at 6 months and 23% of patients alive at 1-year in a Phase 2 trial. Interim results previously presented from this phase II/III study evaluating CA4P in combination with carboplatin (C) + paclitaxel (P) in patients with ATC suggested a survival benefit with the combination therapy. Final survival and safety data are now available. Methods: This is a multicenter, open-label, 2:1 randomized trial for patients with histologically confirmed ATC. 80 out of 180 planned patients were randomized to receive up to 6 cycles of C + P with CA4P (CA4P Arm) or without CA4P (Control Arm). The targeted sample size of 180 patients was not reached due to slow enrollment. After 6 cycles of therapy, patients on the CA4P Arm without progression could continue to receive CA4P until disease progress...