Naturally occurring tumor‐specific CD8 + T‐cell precursors in individuals with and without cancer

Novel Cancer Prevention Strategies in Individuals With Hereditary Cancer Syndromes: Focus on BRCA1, BRCA2, and Lynch Syndrome

Germline pathogenic variants (PVs) in the BRCA1 and BRCA2 genes confer elevated risks of breast, ovarian, and other cancers. Lynch syndrome (LS) is associated with increased risks of multiple cancer types including colorectal and uterine cancers. Current cancer risk mitigation strategies have focused on pharmacologic risk reduction, enhanced surveillance, and preventive surgeries. While these approaches can be effective, they stand to be improved on because of either limited efficacy or undesirable impact on quality of life. The current review summarizes ongoing investigational efforts in cancer risk prevention strategies for patients with germline PVs in BRCA1, BRCA2, or LS-associated genes. These efforts span radiation, surgery, and pharmacology including vaccine strategies. Understanding the molecular events involved in the premalignant to malignant transformation in high-risk individuals may ultimately contribute significantly to novel prevention strategies.

Phase 1 study of safety, tolerability and immunogenicity of the human telomerase (hTERT)-encoded DNA plasmids INO-1400 and INO-1401 with or without IL-12 DNA plasmid INO-9012 in adult patients with solid tumors

Background

Human telomerase reverse transcriptase (hTERT) is frequently classified as a ‘universal’ tumor associated antigen due to its expression in a vast number of cancers. We evaluated plasmid DNA-encoded hTERT as an immunotherapy across nine cancer types.

Methods

A phase 1 clinical trial was conducted in adult patients with no evidence of disease following definitive surgery and standard therapy, who were at high risk of relapse. Plasmid DNA encoding one of two hTERT variants (INO-1400 or INO-1401) with or without plasmid DNA encoding interleukin 12 (IL-12) (INO-9012) was delivered intramuscularly concurrent with the application of the CELLECTRA constant-current electroporation device 4 times across 12 weeks. Safety assessments and immune monitoring against native (germline, non-mutated, non-plasmid matched) hTERT antigen were performed. The largest cohort of patients enrolled had pancreatic cancer, allowing for additional targeted assessments for this tumor type.

Results

Of the 93 enrolled patients who received at least one dose, 88 had at least one adverse event; the majority were grade 1 or 2, related to injection site. At 18 months, 54.8% (51/93) patients were disease-free, with median disease-free survival (DFS) not reached by end of study. For patients with pancreatic cancer, the median DFS was 9 months, with 41.4% of these patients remaining disease-free at 18 months. hTERT immunotherapy induced a de novo cellular immune response or enhanced pre-existing cellular responses to native hTERT in 96% (88/92) of patients with various cancer types. Treatment with INO-1400/INO-1401±INO-9012 drove hTERT-specific IFN-γ production, generated hTERT-specific CD4+ and CD8+ T cells expressing the activation marker CD38, and induced hTERT-specific activated CD8 +CTLs as defined by cells expressing perforin and granzymes. The addition of plasmid IL-12 adjuvant elicited higher magnitudes of cellular responses including IFN-γ production, activated CD4+ and CD8+ T cells, and activated CD8+CTLs. In a subset analysis of pancreatic cancer patients, the presence of immunotherapy-induced activated CD8+ T cells expressing PD-1, granzymes and perforin correlated with survival.

Conclusions

Plasmid DNA-encoded hTERT/IL-12 DNA immunotherapy was well-tolerated, immune responses were noted across all tumor types, and a specific CD8+ phenotype increased by the immunotherapy was significantly correlated with survival in patients with pancreatic cancer.

Strong antigen-specific T-cell immunity induced by a recombinant human TERT measles virus vaccine and amplified by a DNA/viral vector prime boost in IFNAR/CD46 mice

Cancer immunotherapy is seeing an increasing focus on vaccination with tumor-associated antigens (TAAs). Human telomerase (hTERT) is a TAA expressed by most tumors to overcome telomere shortening. Tolerance to hTERT can be easily broken both naturally and experimentally and hTERT DNA vaccine candidates have been introduced in clinical trials. DNA prime/boost strategies have been widely developed to immunize efficiently against infectious diseases. We explored the use of a recombinant measles virus (MV) hTERT vector to boost DNA priming as recombinant live attenuated measles virus has an impressive safety and efficacy record. Here, we show that a MV-TERT vector can rapidly and strongly boost DNA hTERT priming in MV susceptible IFNAR/CD46 mouse models. The cellular immune responses were Th1 polarized. No humoral responses were elicited. The 4 kb hTERT transgene did not impact MV replication or induction of cell-mediated responses. These findings validate the MV-TERT vector to boost cell-mediated responses following DNA priming in humans.

Immune regulation and anti-cancer activity by lipid inflammatory mediators

Rodent and clinical studies have documented that myeloid cell infiltration of tumors is associated with poor outcomes, neutrophilia and lymphocytopenia. This contrasts with increased lymphocyte infiltration of tumors, which is correlated with improved outcomes. Lifestyle parameters, such as obesity and diets with high levels of saturated fat and/or omega (ω)-6 polyunsaturated fatty acids (PUFAs), can influence these inflammatory parameters, including an increase in extramedullary myelopoiesis (EMM). While tumor secretion of growth factors (GFs) and chemokines regulate tumor-immune-cell crosstalk, lifestyle choices also contribute to inflammation, abnormal pathology and leukocyte infiltration of tumors. A relationship between obesity and high-fat diets (notably saturated fats in Western diets) and inflammation, tumor incidence, metastasis and poor outcomes is generally accepted. However, the mechanisms of dietary promotion of an inflammatory microenvironment and targeted drugs to inhibit the clinical sequelae are poorly understood. Thus, modifications of obesity and dietary fat may provide preventative or therapeutic approaches to control tumor-associated inflammation and disease progression. Currently, the majority of basic and clinical research does not differentiate between obesity and fatty acid consumption as mediators of inflammatory and neoplastic processes. In this review, we discuss the relationships between dietary PUFAs, inflammation and neoplasia and experimental strategies to improve our understanding of these relationships. We conclude that dietary composition, notably the ratio of ω-3 vs ω-6 PUFA regulates tumor growth and the frequency and sites of metastasis that together, impact overall survival (OS) in mice.

Mertk on tumor macrophages is a therapeutic target to prevent tumor recurrence following radiation therapy

Radiation therapy provides a means to kill large numbers of cancer cells in a controlled location resulting in the release of tumor-specific antigens and endogenous adjuvants. However, by activating pathways involved in apoptotic cell recognition and phagocytosis, irradiated cancer cells engender suppressive phenotypes in macrophages. We demonstrate that the macrophage-specific phagocytic receptor, Mertk is upregulated in macrophages in the tumor following radiation therapy. Ligation of Mertk on macrophages results in anti-inflammatory cytokine responses via NF-kB p50 upregulation, which in turn limits tumor control following radiation therapy. We demonstrate that in immunogenic tumors, loss of Mertk is sufficient to permit tumor cure following radiation therapy. However, in poorly immunogenic tumors, TGFβ inhibition is also required to result in tumor cure following radiation therapy. These data demonstrate that Mertk is a highly specific target whose absence permits tumor control in combination with radiation therapy.

Effective control of acute myeloid leukaemia and acute lymphoblastic leukaemia progression by telomerase specific adoptive T-cell therapy

Telomerase (TERT) is a ribonucleoprotein enzyme that preserves the molecular organization at the ends of eukaryotic chromosomes. Since TERT deregulation is a common step in leukaemia, treatments targeting telomerase might be useful for the therapy of hematologic malignancies. Despite a large spectrum of potential drugs, their bench-to-bedside translation is quite limited, with only a therapeutic vaccine in the clinic and a telomerase inhibitor at late stage of preclinical validation. We recently demonstrated that the adoptive transfer of T cell transduced with an HLA-A2-restricted T-cell receptor (TCR), which recognize human TERT with high avidity, controls human B-cell chronic lymphocytic leukaemia (B-CLL) progression without severe side-effects in humanized mice. In the present report, we show the ability of our approach to limit the progression of more aggressive leukemic pathologies, such as acute myeloid leukaemia (AML) and B-cell acute lymphoblastic leukaemia (B-ALL). Together, our findings demonstrate that TERT-based adoptive cell therapy is a concrete platform of T cell-mediated immunotherapy for leukaemia treatment.

Lipid Inflammatory Mediators in Cancer Progression and Therapy

Rodent and clinical studies have documented that myeloid cell infiltration of tumors is associated with neutrophilia, lymphocytopenia and poor patient outcomes. This contrasts with lymphocyte infiltration of tumors, which is associated with improved outcomes. Lifestyle parameters such as high fat diet s and omega (ω)-6 polyunsaturated fatty acids (PUFA) intake may influence these inflammatory parameters including extramedullary myelopoiesis that can contribute to a metastatic "niche". While, tumor secretion of growth factors (GFs) and chemokines regulate tumor-immune-cell crosstalk, in this chapter, we also emphasize how lifestyle choices, including, obesity, high-fat and high ω-6 PUFA dietary content, contribute to inflammation and myeloid cell infiltration of tumors. A relationship between obesity and high-fat diets (notably the saturated fats in Western diets) and tumor incidence, metastasis, and poor outcomes is generally accepted. However, the mechanisms of dietary promotion of inflammatory microenvironments and targeted drugs to inhibit the clinical sequel remain an unmet challenge. One approach, modification of dietary intake may have a preventative or therapeutic approach to regulate tumor-associated inflammation and remains an attractive, but little studied intervention.

In vitro activation of hTERT-specific T cell responses in lung cancer patients following chemotherapy

OBJECTIVE

The aim of this study was to examine chemotherapy concomitant in vitro activation of human telomerase reverse transcriptase (hTERT)-specific T cell responses in peripheral blood mononuclear cell (PBMC) samples of patients with advanced non-small cell lung cancer (NSCLC).

METHODS

PBMCs depleted of regulatory T cells were stimulated by peptide loaded dendritic cells (DC) matured either by application of cytokines (cDC) or a Toll-like receptor 7/8-agonist combined with a soluble CD40-ligand (ligDC). The hTERT peptide-specific T cell responses were assessed using flow cytometry for intracellular interferon-γ (IFN-γ).

RESULTS

After cDC activation, T cells producing IFN-γ in response to hTERT were found in PBMC samples of 4 patients. In 2 of these patients the hTERT-specific T cell responses were further increased after ligDC application. However, PBMC of 3 other patients showed little or no induction of hTERT-specific T cell responses as a result of the methods applied during this study.

CONCLUSIONS

These results indicate, that concomitant to chemotherapy hTERT-specific T cell responses can be activated in PBMC of NSCLC patients in vitro. This activation can be further increased by ligDC though the number of responding patients is still limited.

Differential requirements of CD4(+) T-cell signals for effector cytotoxic T-lymphocyte (CTL) priming and functional memory CTL development at higher CD8(+) T-cell precursor frequency

Increased CD8(+) T-cell precursor frequency (PF) precludes the requirement of CD4(+) helper T (Th) cells for primary CD8(+) cytotoxic T-lymphocyte (CTL) responses. However, the key questions of whether unhelped CTLs generated at higher PF are functional effectors, and whether unhelped CTLs can differentiate into functional memory cells at higher PF are unclear. In this study, ovalbumin (OVA) -pulsed dendritic cells (DC(OVA)) derived from C57BL/6, CD40 knockout (CD40(-/-)) or CD40 ligand knockout (CD40L(-/-)) mice were used to immunize C57BL/6, Ia(b-/-), CD40(-/-) or CD40L(-/-) mice, whose PF was previously increased with transfer of 1 × 10(6) CD8(+) T cells derived from OVA-specific T-cell receptor (TCR) transgenic OTI, OTI(CD40(-/-)) or OTI(CD40L(-/-)) mice. All the immunized mice were then assessed for effector and memory CTL responses. Following DC immunization, relatively comparable CTL priming occurred without CD4(+) T-cell help and Th-provided CD40/CD40L signalling. In addition, the unhelped CTLs were functional effectors capable of inducing therapeutic immunity against established OVA-expressing tumours. In contrast, the functional memory development of CTLs was severely impaired in the absence of CD4(+) T-cell help and CD40/CD40L signalling. Finally, unhelped memory CTLs failed to protect mice against lethal tumour challenge. Taken together, these results demonstrate that CD4(+) T-cell help at higher PF, is not required for effector CTL priming, but is required for functional memory CTL development against cancer. Our data may impact the development of novel preventive and therapeutic approaches in cancer patients with compromised CD4(+) T-cell functions.

Immunotherapy of tumors with α2-macroglobulin-antigen complexes pre-formed in vivo

The cell surface receptor CD91/LRP-1 binds to immunogenic heat shock proteins (HSP) and α₂M ligands to elicit T cell immune responses. In order to generate specific immune responses, the peptides chaperoned by HSPs or α₂M are cross-presented on MHC molecules to T cells. While the immunogenic HSPs naturally chaperone peptides within cells and can be purified as an intact HSP-peptide complex, the peptides have had to be complexed artificially to α₂M in previous studies. Here, we show that immunogenic α₂M-peptide complexes can be isolated from the blood of tumor-bearing mice without further experimental manipulation in vitro demonstrating the natural association of tumor antigens with α₂M. The naturally formed immunogenic α₂M-peptide complexes are effective in prophylaxis and therapy of cancer in mouse models. We investigate the mechanisms of cross-presentation of associated peptides and co-stimulation by APCs that interact with α₂M. These data have implications for vaccine design in immunotherapy of cancer and infectious disease.

Simplified sequence-specific oligonucleotide-based polymerase chain reaction protocol to characterize human major histocompatibility complex A*02 and A*24 specificities

Major histocompatibility complex (MHC) multimer technology is used in studies of high scientific and clinical interest for the identification, analysis, purification, and adoptive transfer of virus-specific T cells. MHC peptide multimers are usually specific for MHC A*02 or A*24 specificities because both specificities exhibit a high worldwide frequency. However, commercially available typing methods perform complete typing instead of browsing for these prevailing specificities. In this study we demonstrate an easy and accessible polymerase chain reaction-based method to accurately identify A*02 and A*24 samples in a cost-effective way.

Cytolytic T-cell response against Epstein-Barr virus in lung cancer patients and healthy subjects

Background

This study aimed to examine whether EBV seropositive patients with lung cancer have an altered virus-specific CTL response, as compared to age-matched healthy controls and whether any variation in this response could be attributed to senescence.

Methods

Peripheral blood mononuclear cells from lung cancer patients, age-matched and younger healthy individuals were used to measure EBV-specific CTLs after in vitro amplification with the GLCTLVAML and RYSIFFDYM peptides followed by HLA-multimer staining.

Results

Lung cancer patients and aged-matched controls had significantly lesser EBV-specific CTL than younger healthy individuals. Multimer positive populations from either group did not differ with respect to the percentage of multimer positive CTLs and the intensity of multimer binding.

Conclusions

This study provides evidence that patients with lung cancer exhibit an EBV-specific CTL response equivalent to that of age-matched healthy counterparts. These data warrant the examination of whether young individuals have a more robust anti-tumor response, as is the case with the anti-EBV response.