Antitumor activity of KD3–IFN combined with regulatable expression of TRAIL. (a) Expression of TRAIL increases the antitumor efficacy of the cancer-specific Ad armed with ADP and IFN-α. Established subcutaneous Hep3B tumors were injected intratumorally with PBS (n = 5), 1 × 109PFU of KD3–IFN (n = 11), 1 × 108PFU of TetON–TRAIL (n = 5) or 1 × 109PFU of KD3–IFN plus 1 × 108PFU of TetON–TRAIL (n = 11). The injections were repeated with 1-day intervals for a total of five injections. Mice injected with TetON–TRAIL or TetON–TRAIL+KD3–IFN received Dox with the drinking water. (b) For animals from (a) Kaplan–Meier survival curves were plotted. ADP, Adenovirus Death Protein; IFN, interferon; PFU, plaque forming unit; TRAIL, tumor necrosis factor-related apoptosis-inducing ligand.