Tumors harboring non-synonymous deoxyribonucleic acid (DNA) mutations present peptides containing these mutations as non-self antigens in the context of human leukocyte antigens (HLAs) on the tumor cell surface. A fraction of mutated peptides results in neoantigens capable of generating T cell responses that exclusively target tumor cells. Sensitive detection of these mutations allows for the identification of neoantigens unique to each patient's tumor to be included in a personalized cancer vaccine that targets these neoantigens. This vaccine regimen uses two vaccine vectors as a heterologous prime/boost approach (GRT-C901, ChAd as prime and GRT-R902, samRNA as boost) to stimulate an immune response. This study (GRANITE-ADJUVANT) will explore the anti-tumor activity of this individualized, patient specific immunotherapy in combination with checkpoint inhibitors.
The primary objective is to assess and characterize the antitumor activity and safety and tolerability of adjuvant treatment with an individualized neoantigen vaccine called GRT-C901/GRT-R902 (chimpanzee adenovirus [ChAd] and self-amplifying messenger RNA [samRNA] vectors), in combination with checkpoint inhibitors. Antitumor activity will be based on molecular response in patients with colon cancer who have circulating tumor deoxyribonucleic acid (ctDNA) following surgical resection.