['We have studied the antitumor activity of a novel cyclic amide, CLM94, with anti-vascular endothelial growth factor (VEGF) receptor-2 and antiangiogenic activity in primary anaplastic thyroid cancer (ATC) cells in vitro and in vivo.', 'CLM94 was tested: 1) in two human cell lines (HMVEC-d, dermal microvascular endothelial cells; and 8305C, undifferentiated thyroid cancer) at 0.001-100 μm; 2) in ATC cells at the concentrations of 10, 30, and 50 μm; and 3) in an ATC cell line (AF) in CD nu/nu mice.', 'CLM94 significantly inhibited VEGF receptor-2 and epidermal growth factor receptor phosphorylation in HMVEC-d and proliferation in HMVEC-d and 8305C cells. A significant reduction of proliferation with CLM94 in ATC cells (P < 0.01, ANOVA) and a slight but significant reduction of proliferation with CLM94 30 and 50 μm in normal thyroid follicular cells (P < 0.01, ANOVA) were shown. CLM94 increased the percentage of apoptotic ATC cells dose-dependently (P < 0.001, ANOVA) and inhibited migration (P < 0.01) and invasion (P < 0.001). AF cell line was injected sc in CD nu/nu mice, and tumor masses became detectable 25 d afterward. CLM94 (40 mg/kg · d) significantly inhibited tumor growth (starting 10 d after the beginning of treatment). CLM94 significantly decreased the VEGF-A gene expression in the AF cell line and the VEGF-A protein and microvessel density in AF tumor tissues.'] Is cLM94 , a novel cyclic amide with anti-VEGFR-2 and antiangiogenic properties , active against primary anaplastic thyroid cancer in vitro and in vivo?