Personalized neoantigen vaccine combined with PD-1 blockade increases CD8⁺tissue-resident memory T-cell infiltration in preclinical hepatocellular carcinoma models

Abstract

Background Personalized neoantigen vaccine could induce a robust antitumor immune response in multiple cancers, whose efficacy could be further enhanced by combining with programmed cell death 1 blockade (α-PD-1). However, the corresponding immune response and synergistic mechanisms remain largely unclear. Here, we aimed to develop clinically available combinational therapeutic strategy and further explore its potential antitumor mechanisms in hepatocellular carcinoma (HCC). Methods Neoantigen peptide vaccine (NeoVAC) for murine HCC cell line Hepa1-6 was developed and optimized by neoantigen screening and adjuvant optimization. Then the synergistic efficacy and related molecular mechanisms of NeoVAC combined with α-PD-1 in HCC were evaluated by orthotopic HCC mouse model, single-cell RNA sequencing, tetramer flow cytometry, immunofluorescence, etc. The tumor-killing capacity of CD8 + tissue-resident memory T cells (CD8 + T RMs ) was assessed by orthotopic HCC mouse model, and autologous patient-derived cells. Results NeoVAC, which consisted of seven high immunogenic neoantigen peptides and clinical-grade Poly(I:C), could generate a strong antitumor immune response in HCC mouse models. Significantly, its efficacy could be further improved by combining with α-PD-1, with 80% of durable tumor regression and long-term immune memory in orthotopic HCC models. Moreover, in-depth analysis of the tumor immune microenvironment showed that the percentage of CD8 + T RMs was remarkedly increased in NeoVAC plus α-PD-1 treatment group, and positively associated with the antitumor efficacy. In vitro and in vivo T-cell cytotoxicity assay further confirmed the strong tumor-killing capacity of CD8 + T RMs sorting from orthotopic mouse HCC or patient’s HCC tissue. Conclusions This study showed that NeoVAC plus α-PD-1 could induce a strong antitumor response and long-term tumor-specific immune memory in HCC by increasing CD8 + T RMs infiltration, which might serve as a potential immune-therapeutic target for HCC.

Spleen‐targeted neoantigen DNA vaccine for personalized immunotherapy of hepatocellular carcinoma

“…In our previous study, a Hepa 1‐6 tumor cell‐specific neoantigen (MKARNYLQSLPSKTKVA → MKARNYLQFLPSKTKVA) with high affinity to MHC I H‐2K b (C57BL/6 mice) was identified based on whole‐exome sequencing and transcriptomic sequencing of murine HCC cell line (Hepa 1‐6 cells) and C57BL/6 mouse tail tissue using our proprietary bioinformatics strategies, and further validated with strong antitumor immunogenicity in vivo (Chen et al , 2022). Afterward, the sequence of neoantigen peptide was engineered into a DNA plasmid (pDNA) by using a “PresentER” cassette comprised of endoplasmic reticulum (ER) signal sequence followed by a short peptide/epitope, which enabled readily display of neoantigen epitope on APC cells according to previously reported methods (Fig 1A; Gejman et al , 2018).…”

CD69 serves as a potential diagnostic and prognostic biomarker for hepatocellular carcinoma

“…Increased the number of CD69+CD8+ T cells to enhance antitumor efficacy in mouse model of HCC 39 . CD69+CD8+T cells were predictor for HCC prognosis, and patients showed significantly longer OS time with expressing higher CD69_ CD8a signaling 40 . CD69+ activated CD8+ T cells are significantly reduced in diethylnitrosamine induced HCC models and participate in tumor evasion of immune responses 41 .…”

Engineering PEG10 assembled endogenous virus-like particles with genetically encoded neoantigen peptides for cancer vaccination

“…DEC205 was amplified by PCR from mouse bone marrow derived DCs, and mCherry was fused to the C-terminal of DEC205 and then inserted to pCDH vector for plasmid construction. Hepa1-6 cell derived seven neoantigens were identified in our previous study (Chen et al, 2022), and the DNA sequences were fused to the C-terminal of PEG10 gag domain cloned into pcDNA3.1 vector. The DNA sequence of HBc18-27 epitope was also synthesized and fused to PEG10.…”

“…To prepare eVLP-based neoantigen vaccine, PEG10 gag domain was then fused with 7 tumor neoantigens from Hepa1-6 cell line (Chen et al, 2022) instead of eGFP, and the productivity of eVLP was evaluated by quantifying the total amount of proteins produced from one 10-cm dish of transfected HEK293T cells (eVLP vs control: 212±7.388 μg vs 76.59±7.463 μg) (Figure S2). But in vivo, solely relying on the eVLP-antigen complex for antigen delivery to antigen-presenting cells (APCs) and immune response activation is not efficient.…”