Allogeneic GM-CSF-secreting tumor cell immunotherapies generate potent anti-tumor responses comparable to autologous tumor cell immunotherapies

Genomic analysis of the prognostic value of colony-stimulating factors (CSFs) and colony-stimulating factor receptors (CSFRs) across 24 solid cancer types

Background

The prognostic roles of granulocyte-/granulocyte-macrophage colony-stimulating factor (G-/GM-CSF) and its receptors (CSFRs) from the genomic perspective remain controversial. The aim of our study was to evaluate their prognostic value in multiple cancer types by analyzing omics data.

Methods

The omics data of G-/GM-CSF and receptors were obtained from the cBioportal database. Cutoff values were determined by X-tile. Overall survival (OS) was assessed by Kaplan–Meier curves. Differentially expressed genes (DEGs) and common regulated genes were analyzed using R software and Venny 2.1.0, while enrichment pathway analyses were performed by Metascape.

Results

A comprehensive mRNA analysis was performed in 8,565 patients across 24 cancer types. The combination subgroup of CSF2 and its receptors with high expression and favorable prognosis was associated with the activation of immune-related pathways, while the subgroup with unfavorable prognosis was associated with the activation of inflammatory and cellular pathways. As for the combination subgroup of CSF3 and its receptor, the high expression and poor prognosis subgroup was accompanied by the activation of inflammation and signaling transduction pathways.

Conclusions

The prognostic value of CSFs and CSFRs are cancer-type dependent. Therefore, personalized risk stratification based on CSF and CSFR pathway should be considered for cancer patients.

Cancer immunotherapy: moving forward with peptide T cell vaccines

Recent advances in cancer immunology, such as the discovery of immune checkpoint inhibitors, have validated immune cells as potential key players for effective cancer treatment. The efficacy of these therapies seems to be codependent on a tumor-reactive T lymphocyte response. For many years, numerous attempts and strategies in developing vaccines to generate tumor-reactive T cells have yielded poor results in the clinic due to suboptimal immunogenicity and the inability to overcome an immunosuppressive tumor microenvironment. In this review, we summarize past and current advances in T cell vaccines and describe our experience in developing optimized methods for antigen/adjuvant selection and vaccine administration in order to induce powerful anti-tumor responses.

Systemic Tolerance Mediated by Melanoma Brain Tumors Is Reversible by Radiotherapy and Vaccination

PURPOSE

Immune responses to antigens originating in the central nervous system (CNS) are generally attenuated, as collateral damage can have devastating consequences. The significance of this finding for the efficacy of tumor-targeted immunotherapies is largely unknown.

EXPERIMENTAL DESIGN

The B16 murine melanoma model was used to compare cytotoxic responses against established tumors in the CNS and in the periphery. Cytokine analysis of tissues from brain tumor-bearing mice detected elevated TGFβ secretion from microglia and in the serum and TGFβ signaling blockade reversed tolerance of tumor antigen-directed CD8 T cells. In addition, a treatment regimen using focal radiation therapy and recombinant Listeria monocytogenes was evaluated for immunologic activity and efficacy in this model.

RESULTS

CNS melanomas were more tolerogenic than equivalently progressed tumors outside the CNS as antigen-specific CD8 T cells were deleted and exhibited impaired cytotoxicity. Tumor-bearing mice had elevated serum levels of TGFβ; however, blocking TGFβ signaling with a small-molecule inhibitor or a monoclonal antibody did not improve survival. Conversely, tumor antigen-specific vaccination in combination with focal radiation therapy reversed tolerance and improved survival. This treatment regimen was associated with increased polyfunctionality of CD8 T cells, elevated T effector to T regulatory cell ratios, and decreased TGFβ secretion from microglia.

CONCLUSIONS

These data suggest that CNS tumors may impair systemic antitumor immunity and consequently accelerate cancer progression locally as well as outside the CNS, whereas antitumor immunity may be restored by combining vaccination with radiation therapy. These findings are hypothesis-generating and warrant further study in contemporary melanoma models as well as human trials.

Dendritic cell-based vaccination in cancer: therapeutic implications emerging from murine models

Dendritic cells (DCs) play a pivotal role in the orchestration of immune responses, and are thus key targets in cancer vaccine design. Since the 2010 FDA approval of the first cancer DC-based vaccine (Sipuleucel-T), there has been a surge of interest in exploiting these cells as a therapeutic option for the treatment of tumors of diverse origin. In spite of the encouraging results obtained in the clinic, many elements of DC-based vaccination strategies need to be optimized. In this context, the use of experimental cancer models can help direct efforts toward an effective vaccine design. This paper reviews recent findings in murine models regarding the antitumoral mechanisms of DC-based vaccination, covering issues related to antigen sources, the use of adjuvants and maturing agents, and the role of DC subsets and their interaction in the initiation of antitumoral immune responses. The summary of such diverse aspects will highlight advantages and drawbacks in the use of murine models, and contribute to the design of successful DC-based translational approaches for cancer treatment.

Preclinical evidence that PD1 blockade cooperates with cancer vaccine TEGVAX to elicit regression of established tumors

Biomarker studies have shown that expression of the T-cell coregulatory ligand PDL1 on tumor cells correlates with clinical responsiveness to the PD1 antibody nivolumab. Here, we report the findings of a preclinical cancer vaccine study demonstrating vaccine-dependent PDL1 upregulation in the tumor microenvironment. We formulated an IFNγ-inducing cancer vaccine called TEGVAX that combined GM-CSF and multiple Toll-like receptor agonists to increase the number of activated dendritic cells. Treatment of established tumors with TEGVAX retarded tumor growth in a manner associated with enhanced systemic antitumor immunity. Unexpectedly, TEGVAX also upregulated PDL1 expression in the tumor microenvironment, possibly explaining why tumors were not eliminated completely. In support of this likelihood, PDL1 upregulation in this setting relied upon IFNγ-expressing tumor-infiltrating CD4(+) and CD8(+) T cells and administration of a PD1-blocking antibody with TEGVAX elicited complete regression of established tumors. Taken together, our findings provide a mechanistic rationale to combine IFNγ-inducing cancer vaccines with immune checkpoint blockade.

Various ways to improve whole cancer cell vaccines

Immunotherapy based on whole cancer cell vaccines is regarded as a promising avenue for cancer treatment. However, limited efficacy in the first human clinical trials calls for more optimized whole cancer cell vaccines and better patient selection. It is suggested that whole cancer cell vaccines consist preferably of immunogenically killed autologous cancer stem cells associated with dendritic cells. Adjuvants should stimulate both immune effector cells and memory cells, which could be achieved through their correct dosage and timing of administration. There are indications that whole cancer cell vaccination is less effective in patients who are immunocompromised, who have specific genetic defects in their immune or cancer cells, as well as in patients in an advanced cancer stage. However, such patients form the bulk of enrolled patients in clinical trials, prohibiting an objective evaluation of the true potential of whole cancer cell immunotherapy. Each key point will be discussed.

Immune-dependent and independent antitumor activity of GM-CSF aberrantly expressed by mouse and human colorectal tumors

Granulocyte-macrophage colony-stimulating factor (GM-CSF/CSF2) is a cytokine produced in the hematologic compartment that may enhance antitumor immune responses, mainly by activation of dendritic cells. Here, we show that more than one-third of human colorectal tumors exhibit aberrant DNA demethylation of the GM-CSF promoter and overexpress the cytokine. Mouse engraftment experiments with autologous and homologous colon tumors engineered to repress the ectopic secretion of GM-CSF revealed the tumor-secreted GM-CSF to have an immune-associated antitumor effect. Unexpectedly, an immune-independent antitumor effect was observed that depended on the ectopic expression of GM-CSF receptor subunits by tumors. Cancer cells expressing GM-CSF and its receptor did not develop into tumors when autografted into immunocompetent mice. Similarly, 100% of the patients with human colon tumors that overexpressed GM-CSF and its receptor subunits survived at least 5 years after diagnosis. These data suggest that expression of GM-CSF and its receptor subunits by colon tumors may be a useful marker for prognosis as well as for patient stratification in cancer immunotherapy.

Novel immunotherapy for metastatic bladder cancer using vaccine of human interleukin-2 surface-modified MB 49 cells

OBJECTIVE

To develop a novel protein-anchor technology to immobilize human interleukin-2 on tumor cells to induce antitumor immunity.

METHODS

Interleukin-2 surface-modified MB49 cells were prepared as a vaccine. Subcutaneous and pulmonary metastatic mouse models of MB49 bladder cancer were used to evaluate the antitumor efficiency of the vaccine. Immunohistochemistry, flow cytometric, and cytotoxic T-lymphocyte assay were performed to assess the proportion and cytotoxicity of the T lymphocytes.

RESULTS

The IL-2 surface-modified MB49 cell vaccine inhibited tumor growth and extended the survival of the mice, and the vaccine-cured mice effectively resisted the second MB49 but not the RM-1 prostate cancer cell challenge. Furthermore, more cytotoxicity on the MB49 cells and more CD4-positive, CD8-positive T cells appeared in the vaccine-treated group.

CONCLUSION

The results of our study have demonstrated that the human interleukin-2 surface-modified MB49 bladder cancer cell vaccine induced specific antitumor immunity and was efficient against metastatic bladder cancer.

Vaccination with Human Induced Pluripotent Stem Cells Creates an Antigen-Specific Immune Response Against HIV-1 gp160

Induced pluripotent stem cells (iPSCs) are artificially derived from somatic cells that have been transduced with defined reprogramming factors. A previous report has indicated the possibility of using iPSCs as an immune stimulator to generate antigen-specific immunity. In our current study, we have investigated whether human iPSCs (hiPSCs) have the ability to enhance specific immune response against a human immunodeficiency virus type 1 (HIV-1) antigen in a xenogenic mouse model. Our results show that BALB/c mice immunized with hiPSCs transduced with an adenoviral vector encoding HIV-1 gp160 exhibited prominent antigen-specific cellular immune responses. We further found that pre-treatment of hiPSCs with ionizing radiation promotes the secretion of pro-inflammatory cytokines such as interleukin-1 alpha (IL-1α), IL-12, and IL-18. These cytokines might promote the activation of antigen-presenting cells and the effective induction of cellular immunity. Our present findings thus demonstrate that a hiPSCs-based vaccine has the potential to generate cellular immunity against viral antigens such as HIV-1 gp160 in a xenogenic condition.

Cellular vaccine approaches

Therapeutic cancer vaccines aim to generate immunologic targeting of cancer cells through the induction of effective cellular and antibody-mediated responses specific for antigens selectively expressed by the tumor. Exploiting the adaptive immune system as a targeted tool against cancer is appealing in its capacity for exact specificity and avoidance of unintended tissue damage seen by other conventional agents such as chemotherapy. There are a multitude of challenges to designing effective vaccine strategies. The components of a vaccine strategy start with the challenges of selecting immunogenic, tumor-specific antigen targets, choosing a platform with which to deliver the antigens, and enhancing the immunostimulatory context in which the vaccines are delivered. Although understanding the components of effective T-cell activation is essential, successful effector T cells can only be produced if there is also an understanding of the natural processes that tumors exploit to down-modulate active immune responses. These processes are normally used to down-regulate excessive tissue-destructive immune responses against infectious agents once the infecting agent is cleared or to prevent autoimmunity. Advances in molecular and cellular technologies continue to provide insights into the regulation of immune responses both to infectious agents and to cancer that may be manipulated to tip the balance in favor of tumor regression over immune tolerance. This review focuses primarily on cellular vaccines. For the purpose of this review, cellular vaccines are defined as vaccines that use whole cells or cell lysates either as the source of antigens or the platform in which to deliver the antigens. Dendritic cell (DC)-based vaccines focus on ex vivo antigen delivery to DCs. Other platforms such as GVAX (tumor cells genetically engineered to produce granulocyte-macrophage colony-stimulating factor) aim to deliver tumor antigens in vivo in an immune stimulatory context to endogenous DCs. Because data continue to emerge regarding the importance of the maturation status of DCs and the importance of the particular subset of DCs being targeted, these insights will be integrated into vaccine strategies that are likely to produce more effective vaccines.