An open label phase II study of modified vaccinia ankara (MVA) expressing the tumor antigen 5T4 given in conjunction with chemotherapy: Safety and immunogenicity before, during and after chemotherapy

2578 Background: 5T4 is a tumour associated antigen that is widely expressed on the surface of most human adenocarcinomas, including colorectal, but rarely in normal cells. Modified Vaccinia Ankara (MVA) has been employed as a vaccine vector to deliver 5T4 (TroVax). Previously, TroVax has been evaluated in a phase I/II clinical trial in Duke’s D colorectal cancer patients. TroVax was shown to be safe and well tolerated and induced 5T4 specific immune responses in most patients. Furthermore, periods of disease stabilisation up to 18 months were observed. Methods: Two phase II clinical trials were initiated in which TroVax was administered in conjunction with either 5-FU/leukovorin and irinotecan (TV2-Irinotecan trial) or 5-FU/leukovorin and oxaliplatin (TV2-Oxaliplatin) in patients with advanced colorectal cancer. Both trials are open label and entail the administration of up to 6 injections of TroVax, 2 prior to, 2 during and 2 post-chemotherapy. The primary objective is to assess the effect of repeat cyc...