Residue substitution enhances the immunogenicity of neoepitopes from gastric cancers

Area of Science:

• Immunology
• Oncology
• Biochemistry

Background:

• Neoantigens derived from tumor gene mutations can elicit specific immune responses.
• Neoantigen-based immunotherapies are under clinical investigation for cancer treatment.
• Gastric cancer immunotherapy efficacy can potentially be improved by enhancing neoepitope immunogenicity.

Purpose of the Study:

• To characterize the efficacy of modified neoepitopes in boosting immunogenicity against gastric cancer.
• To investigate the impact of specific amino acid substitutions (P1Y and P2L) on neoepitope-HLA binding and stability.
• To evaluate the capacity of altered neoepitopes to stimulate CD8+ T cell responses and cytotoxic activity.

Main Methods:

• Whole-exome sequencing data from a gastric cancer patient were analyzed to identify neoepitopes.
• Neoepitopes were modified via P1Y and P2L substitutions.
• T2 binding and stability assays assessed neoepitope-HLA complex affinities.
• Dendritic cells (DCs) presented neoepitopes to stimulate CD8+ T cells.
• ELISA, flow cytometry, and LDH assays measured cytokine release (IFN-γ, TNF-α), T cell proliferation, and cytotoxicity.

Main Results:

• Residue substitution in neoepitopes increased their affinity and stability with HLA molecules.
• Altered neoepitopes presented by DCs induced greater CD8+ T cell proliferation and IFN-γ release compared to wild-type neoepitopes.
• CD8+ T cells stimulated by altered neoepitopes exhibited enhanced killing of target cells via increased secretion of IFN-γ, TNF-α, and perforin.

Conclusions:

• Modified neoepitopes demonstrate superior immunogenicity compared to their wild-type counterparts.
• Amino acid residue substitution represents a viable strategy for enhancing neoantigen immunogenicity in cancer immunotherapy.
• This approach offers a novel therapeutic avenue for targeting neoantigens in gastric cancer and potentially other malignancies.