Combination immunotherapy of glioblastoma with dendritic cell cancer vaccines, anti-PD-1 and poly I:C

Abstract

Glioblastoma (GBM) is a lethal cancer with limited therapeutic options. Dendritic cell (DC)-based cancer vaccines provide a promising approach for GBM treatment. Clinical studies suggest that other immunotherapeutic agents may be combined with DC vaccines to further enhance antitumor activity. Here, we report a GBM case with combination immunotherapy consisting of DC vaccines, anti-programmed death-1 (anti-PD-1) and poly I:C as well as the chemotherapeutic agent cyclophosphamide that was integrated with standard chemoradiation therapy, and the patient remained disease-free for 69 months. The patient received DC vaccines loaded with multiple forms of tumor antigens, including mRNA-tumor associated antigens (TAA), mRNA-neoantigens, and hypochlorous acid (HOCl)-oxidized tumor lysates. Furthermore, mRNA-TAAs were modified with a novel TriVac technology that fuses TAAs with a destabilization domain and inserts TAAs into full-length lysosomal associated membrane protein-1 to enhance major histocompatibility complex (MHC) class I and II antigen presentation. The treatment consisted of 42 DC cancer vaccine infusions, 26 anti-PD-1 antibody nivolumab administrations and 126 poly I:C injections for DC infusions. The patient also received 28 doses of cyclophosphamide for depletion of regulatory T cells. No immunotherapy-related adverse events were observed during the treatment. Robust antitumor CD4⁺ and CD8⁺ T-cell responses were detected. The patient remains free of disease progression. This is the first case report on the combination of the above three agents to treat glioblastoma patients. Our results suggest that integrated combination immunotherapy is safe and feasible for long-term treatment in this patient. A large-scale trial to validate these findings is warranted.

Keywords: DC vaccine; Glioblastoma multiforme; Neoantigens; Tumor-associated antigens.

Graphical abstract

Fig. 1

Schematic diagram of the treatment process and magnetic resonance imaging scan results. (A) The process of an integrated combination immunotherapy from 2017 to 2022. The arrow indicates the timing of the events. (B) Magnetic resonance imaging (MRI) results during the treatment. The labeled month refers to the time after surgery. RT: radiotherapy. TMZ: temozolomide; DC: dendritic cell; PD-1: programmed death-1; CTX: cyclophosphamide; CTL: cytotoxic T lymphocytes.

Fig. 2

Identification and selection of tumor associated antigens and neoantigens. (A) Heatmap of mRNA expression of tumor associated antigens (TAAs) in the patient's tumor sample. The mRNAs of the indicated TAAs in tumor samples from resection were assayed by quantitative PCR (qPCR) in triplicate, and the expression levels of the measured genes were expressed as the mean fold changes. (B) Procedure for neoantigen identification and selection. The number of identified candidates is indicated for each step. (C) In vitro T-cell responses to synthesized neoantigen and wild-type peptides. Peripheral blood mononuclear cells (PBMCs) were stimulated with autologous dendritic cell (DC) pulsed with antigen peptides for 12 days and restimulated for 6 h. T cells were stained for intracellular expression of tumor necrosis factor alpha (TNF-α) and interferon-gamma (IFN-γ), and percentages of cytokine-expressing CD4⁺ or CD8⁺ T cells are shown. NGS: next generation sequencing.

Fig. 3

Antigen-specific T-cell responses to tumor associated antigens (TAAs) and neoantigens. All timepoint data was normalized with the data that collected before DC vaccine treatment. (A) Kinetics of antigen-specific CD4⁺ and CD8⁺ T-cell responses against TAAs. (B) Kinetics of antigen-specific CD4⁺ and CD8⁺ T-cell responses against neoantigens. Dotted lines in each panel indicate DC immunizations for that specific TAA or neoantigen. IFN-γ: interferon-γ.

Fig. 4

Dynamics of peripheral immune cell subsets and cytokine levels. (A) Cell counts of total lymphocytes and subsets during the course of the treatment. (B) Cytokine levels during the course of the treatment. Dotted lines in each panel indicate dendritic cell (DC) immunizations for any tumor associated antigens or neoantigens. NK: natural killer; TNF: tumor necrosis factor; IL: interleukin.