A Study of a Personalized Cancer Vaccine Targeting Shared Neoantigens

Tumors harboring non-synonymous deoxyribonucleic acid (DNA) mutations can present peptides containing these mutations as non-self antigens in the context of HLA on the tumor cell surface. A fraction of mutated peptides result in neoantigens capable of generating T-cell responses that exclusively target tumor cells. Some of these tumor-specific neoantigens are known or expected to be common across a subset of patients and are called shared neoantigens. This study aims to target shared neoantigens using a heterologous prime/boost therapeutic vaccine approach (GRT-C903 first followed by GRT-R904) in combination with checkpoint blockade to stimulate an immune response. This study will explore the safety and early clinical activity of this neoantigen-based immunotherapy intended to induce T-cell responses specific for the shared neoantigens contained within the therapeutic vaccine. Phase 1 will test multiple doses and combinations with checkpoint blockade and Phase 2 will test for early signs of clinical activity using a vaccine regimen based on Phase 1 data.