GUCY2C Prime-Boost Vaccination for Advanced Colorectal and Small Bowel Adenocarcinomas

This is an open-label, non-randomized, single-center, dose-escalation Phase 1 trial using a heterologous prime-boost strategy of vaccination with Ad5.F35-hGUCY2C-PADRE and recombinant Listeria monocytogenes (Lm-GUCY2C) vaccines in patients with advanced solid tumors including colorectal cancer, and small bowel adenocarcarcinomas who have progressed on available standard therapies. The study treatment will begin with Ad5.F35-hGUCY2C-PADRE vaccine administered intramuscularly (IM) once at the recommended Phase 2 dose (RPTD) dose, followed four weeks later by two administrations of Lm-GUCY2C intravenously (IV) at one of three escalating dose levels, four weeks apart. Treatment-related toxicity and development of immune responses will be evaluated every four weeks through week 8 after initial Lm-GUCY2C vaccination. Primary endpoints will include maximum tolerated dose (MTD) and safety and tolerability as measured by treatment emergent adverse events (TEAEs) and clinically significant changes in safety laboratory tests in the dose limiting toxicity (DLT) evaluation period defined as 4 weeks after the initial Lm-GUCY2C vaccination.