Therapeutic efficacy of targeting TWEAK/Fn14 in gastrointestinal cancer. The effect of TWEAK/Fn14 blockade on gastrointestinal cancer was examined in vivo. Colon-26 was implanted in the flank of the syngeneic BALB/c mice. The mice were treated with 0.3 mg of each mAb every other day for 3 weeks. The control mice received control IgG. The mean tumor volume at 1, 2, 3 and 4 weeks after starting treatment was; anti-TWEAK mAb, 243, 279, 656 and 2,311 mm3, respectively; anti-Fn14 mAb, 91, 111, 676 and 1,713 mm3, respectively; control, 781, 870, 1,722 and 5,747 mm3, respectively. n=6 for each group. Data points, mean tumor size; bars, SD. Either TWEAK or Fn14 blockade inhibited tumor growth compared to the controls. The statistical differences were; TWEAK blockade, 0.005, <0.0001, 0.02 and 0.07 at 1, 2, 3 and 4 weeks, respectively, compared to the control; Fn14 blockade, 0.0007, <0.0001, 0.06 and 0.02, respectively, compared to the control.