Adenovirus 5/F35-Human Guanylyl Cyclase C-PADRE(Thomas Jefferson University)

This is an open-label, dose-finding, Phase 2A/2B study of Ad5.F35-hGCC-PADRE as a vaccine for gastrointestinal (GI) malignancies (pancreatic, colorectal, esophageal, gastric, and small bowel adenocarcinomas) who have received surgical resection and standard adjuvant therapy. In Phase 2A, patients will be given multiple administrations of Ad5.F35-hGCC-PADRE intramuscularly at 1 of 3 dose levels. Treatment-related toxicity and development of immune responses to GCC will be evaluated at Weeks 5, 9, and 13 after the initial vaccination (Week 1). Primary safety endpoints will examine adverse events (AEs), injection-site reactions and clinically-significant changes in safety laboratory tests. Primary efficacy endpoints include the development of GCC-specific T-cell responses at different dose levels (1011, 1012, and 5x1012 virus particles or vp). In Phase 2B Dose Expansion cohort, a group of 20 colon cancer patients who are ctDNA+ by CLIA-certified standard of care assays will receive a single administration of Ad5.F35-hGCC-PADRE vaccine intramuscularly at prespecified dose of 1012 vp. Phase 2b is NOT randomized. Primary safety endpoints will examine AEs, injection-site reactions and clinically significant changes in safety laboratory tests. The primary efficacy endpoints include GCC-specific T-cell responses at 1012 vp in ctDNA+ patients. Additional exploratory endpoint will determine elimination of minimal residual disease (MRD) by ctDNA clearance.