Fusion of the dendritic cell-targeting chemokine MIP3α to melanoma antigen Gp100 in a therapeutic DNA vaccine significantly enhances immunogenicity and survival in a mouse melanoma model

Abstract

BackgroundAlthough therapeutic cancer vaccines have been mostly disappointing in the clinic, the advent of novel immunotherapies and the future promise of neoantigen-based therapies have created the need for new vaccine modalities that can easily adapt to current and future developments in cancer immunotherapy. One such novel platform is a DNA vaccine fusing the chemokine Macrophage Inflammatory Protein-3α (MIP-3α) to an antigen, here melanoma antigen gp100. Previous published work has indicated that MIP-3α targets nascent peptides to immature dendritic cells, leading to processing by class I and II MHC pathways. This platform has shown enhanced efficacy in prophylactic melanoma and therapeutic lymphoma model systems.MethodsThe B16F10 melanoma syngeneic mouse model system was utilized, with a standard therapeutic protocol: challenge with lethal dose of B16F10 cells (5 × 104) on day 0 and then vaccinate by intramuscular electroporation with 50 μg plasmid on days three, 10, and 17. Efficacy was assessed by analysis of tumor burden, tumor growth, and mouse survival, using the statistical tests ANOVA, mixed effects regression, and log-rank, respectively. Immunogenicity was assessed by ELISA and flow cytometric methods, including intracellular cytokine staining to assess vaccine-specific T-cell responses, all tested by ANOVA.ResultsWe demonstrate that the addition of MIP3α to gp100 significantly enhances systemic anti-gp100 immunological parameters. Further, chemokine-fusion vaccine therapy significantly reduces tumor burden, slows tumor growth, and enhances mouse overall survival compared to antigen-only, irrelevant-antigen, and mock vaccines, with efficacy mediated by both CD4+ and CD8+ effector T cells. Antigen-only, irrelevant-antigen, and chemokine-fusion vaccines elicit significantly higher and similar CD4+ and CD8+ tumor-infiltrating lymphocyte (TIL) levels compared to mock vaccine. However, vaccine-specific CD8+ TILs are significantly higher in the chemokine-fusion vaccine group, indicating that the critical step induced by the fusion vaccine construct is the enhancement of vaccine-specific T-cell effectors.ConclusionsThe current study shows that fusion of MIP3α to melanoma antigen gp100 enhances the immunogenicity and efficacy of a DNA vaccine in a therapeutic B16F10 mouse melanoma model. This study analyzes an adaptable and easily produced MIP3α-antigen modular vaccine platform that could lend itself to a variety of functionalities, including combination treatments and neoantigen vaccination in the pursuit of personalized cancer therapy.Electronic supplementary materialThe online version of this article (doi:10.1186/s40425-016-0189-y) contains supplementary material, which is available to authorized users.

A Cancer Cell Program Promotes T Cell Exclusion and Resistance to Checkpoint Blockade

“…Second, inhibition of genes from the repressed component of the program in malignant melanoma cells conferred resistance to CD8 + T cells in a genome-wide CRISPR screen (p =1.67 × 10 −3 , hypergeometric test) (Patel et al, 2017). Third, the program marks the suppression of physical interactions between resistant malignant cells and other cell types in the tumor microenvironment, including MHC I:TCR (T cells), CD58:CD2 (T cells), and IL1RAP:IL1B (macrophages) (Figure 3B and STAR Methods), as well as the senescence-associated secretory phenotype (SASP) (p = 4.3 × 10 −166 and 3.6 × 10 −3 , one-sided t test and mixed effects, respectively; Figure 2D), which has been shown to enhance T cell responses (Gordy et al, 2016). …”

IFN-α and 5-Aza-2’-deoxycytidine enhance the anti-tumor efficacy of a dendritic- cell targeting MIP3a-Gp100-Trp2 DNA vaccine by affecting T-cell recruitment and tumor microenvironment gene expression

“…Previous work from our laboratory has shown that the fusion of MIP3α to gp100 enhanced the immunogenicity and efficacy of a DNA vaccine 4 . In the current experiment, a 100 amino acid region of the melanoma-associated antigen tyrosinase-related protein 2 (Trp2) was added to the construct to create a two-antigen vaccine referred to as MIP3α-GpTrp or MGpTrp.…”

“…MIP3α is fused to amino acids 25-235 of the human melanoma-associated antigen gp100 proved superior compared to vaccines comprised of defective MIP3α (D-MIP3α) fused to gp100 or MIP3α fused to an irrelevant antigen 4 .…”

“…The original plasmid encoded the MIP3α-hgp100 fusion sequence, where the antigen includes amino acids 25-235 of human gp100, as described 4 . A vaccine of mouse MIP3α fused to the combined antigens construct consisting of the hgp100 construct and mouse tyrosinase-related protein 2 (Trp2, amino acids 170-269) was created.…”

Transcutaneous delivery of DNA/mRNA for cancer therapeutic vaccination

“…116 Transcutaneous genetic vaccination of other melanoma-specific antigens, such as pg100 and MART-1, was also reported to activate T cells or trigger associative recognition after administration by gene guns 117 or eletroporation. 118,119 An enhanced human tyrosinase DNA antigen was designed using a codon-and RNA-optimized approach and it was found to reduce the frequencies of myeloidderived suppressor cells in a syngeneic prophylactic and therapeutic murine model, suggesting a potential strategy for preventing tumor progression and immune escape. 120 Despite the promising results obtained in animal models, it is not easy to evoke sufficient immune responses for significant clinical benefits.…”