CEACAM5 and neoplasm: 73 The recombinant viruses produce tumor-associated antigens, as viruses are inherently immunogenic. 74 In several clinical trials, the carcinoembryonic antigen (CEA) generated T-cell response was observed, along with disease stabilization in up to 40% of metastatic cancer patients. 75 Similarly, a phase II clinical trial examining the effectiveness of chemotherapy in conjunction with non-replicating canarypox virus vaccination with T-cell costimulatory molecule B7.1 showed that 50% of patients exhibited anti-CEA-specific T-cell responses. 76