Tumor inhibition. (A) Growth inhibition of human lung cancer (A549) transplanted into athymic nude mice by intravenous administration of tTF-NGR (n = 11) compared with the administration of tTF (n = 4) or saline (0.9% NaCl, n = 10). Arrows indicate the time points of injection. Data are presented as means ± SE. The tumor growth was significantly retarded by tTF-NGR after the fourth injection in comparison to the saline group (P = .008, Mann-Whitney test) and after the fifth tTF-NGR injection in comparison to the tTF group (P = .007, Mann-Whitney test). * denotes first day of statistical significance between tTF-NGR and saline. (B) Effect of tTF-NGR on the growth of melanoma xenotransplants in mice. Growth inhibition of human melanoma (M21) transplanted into athymic nude mice by intravenous administration of tTF-NGR (n = 7) compared with the administration of tTF (n = 11) or saline (0.9% NaCl, n = 9). Time (days) shown represent days after first treatment. Arrows indicate the time point of injection. Data are presented as means ± SE. The tumor growth was significantly retarded on day 4 of the tTF-NGR treatment in comparison to the saline group (P = .016, Mann-Whitney test) and on day 5 in comparison to the tTF group (P = .035, Mann-Whitney test). * denotes first day of statistical significance between tTF-NGR and saline. (C) Effect of tTF-NGR on the growth of fibrosarcoma xenotransplants in mice. Growth inhibition of human fibrosarcoma (HT1080) transplanted into athymic nude mice by intravenous administration of tTF-NGR (n = 8) compared with the administration of tTF (n = 14) or saline (0.9% NaCl, n = 15). Time (days) shown represent days after first treatment. Arrows indicate the time point of injection. Data are presented as means ± SE. The tumor growth was significantly retarded at day 6 of the tTF-NGR treatment in comparison to the saline group (P = .023, Mann-Whitney test) and at day 6 in comparison to the tTF group (P = .02, Mann-Whitney test). * denotes statistical significance between tTF-NGR and saline.