Clinical and immunological responses to a DNA fusion vaccine in patients with carcinoembryonic antigen-expressing tumors: A Cancer Research UK phase I/II study.

2579 Background: We have designed DNA fusion vaccines encoding a tumor-derived peptide, linked to a tolerance-breaking domain sequence (DOM) from tetanus toxin. One peptide sequence from prostate cancer is in clinical trial with CD8+ T-cell responses detected in 60% of patients. For patients with CEA expressing cancers, the target peptide is an HLA-A2-binding sequence, CAP-1 (CEA605–613). Methods: We undertook a single dose level, two-arm phase I/II study to examine the safety and immunogenicity of the DNA fusion vaccine (p.DOM-CAP-1) in patients with CEA-expressing cancers (bowel, lung, and breast cancer). 1mg/dose of DNA was given at weeks 0, 1, 2, 4, 8 and 12. 15 patients with measurable disease were recruited to arm I, 12 patients without radiological evidence of disease to arm II of the study. Results: Interim immunological results reveal humoral and cellular responses to the DOM vaccine component in both arms, confirming successful delivery of the vaccine. CAP1–specific CD8+ T-cells were detected us...