NEO-PV-01

mRNA vaccines are regarded as a highly promising avenue for next‐generation cancer therapy. Nevertheless, the intricacy of production, inherent instability, and low expression persistence of linear mRNA significantly restrict their extensive utilization. Circular RNAs (circRNAs) offer a novel solution to these limitations due to their efficient protein expression ability, which can be rapidly generated in vitro without the need for extra modifications. Here, we present a novel neoantigen vaccine based on circRNA that induces a potent anti‐tumor immune response by expressing hepatocellular carcinoma‐specific tumor neoantigens. By cyclizing linearRNA molecules, we were able to enhance the stability of RNA vaccines and form highly stable circRNA molecules with the capacity for sustained protein expression. We confirmed that neoantigen‐encoded circRNA can promote dendritic cell (DC) activation and enhance DC‐induced T‐cell activation in vitro, thereby enhancing T‐cell killing of tumor cells. Encapsulating neoantigen‐encoded circRNA within lipid nanoparticles for in vivo expression has enabled the creation of a novel circRNA vaccine platform. This platform demonstrates superior tumor treatment and prevention in various murine tumor models, eliciting a robust T‐cell immune response. Our circRNA neoantigen vaccine offers new options and application prospects for neoantigen immunotherapy in solid tumors.

Outcomes for patients with glioblastoma (GBM) remain poor despite multimodality treatment with surgery, radiation, and chemotherapy. There are few immunotherapy options due to the lack of tumor immunogenicity. Several clinical trials have reported promising results with cancer vaccines. To date, studies have used data from a single tumor site to identify targetable antigens, but this approach limits the antigen pool and is antithetical to the heterogeneity of GBM. We have implemented multisector sequencing to increase the pool of neoantigens across the GBM genomic landscape that can be incorporated into personalized peptide vaccines called NeoVax.

In this study, we report the findings of four patients enrolled onto the NeoVax clinical trial (NCT0342209).

Immune reactivity to NeoVax neoantigens was assessed in peripheral blood mononuclear cells pre- and post-NeoVax for patients 1 to 3 using IFNγ-ELISPOT assay. A statistically significant increase in IFNγ producing T cells at the post-NeoVax time point for several neoantigens was observed. Furthermore, a post-NeoVax tumor biopsy was obtained from patient 3 and, upon evaluation, revealed evidence of infiltrating, clonally expanded T cells.

Collectively, our findings suggest that NeoVax stimulated the expansion of neoantigen-specific effector T cells and provide encouraging results to aid in the development of future neoantigen vaccine–based clinical trials in patients with GBM. Herein, we demonstrate the feasibility of incorporating multisector sampling in cancer vaccine design and provide information on the clinical applicability of clonality, distribution, and immunogenicity of the neoantigen landscape in patients with GBM.