In vitro anti-tumor immune response induced by dendritic cells transfected with EBV-LMP2 recombinant adenovirus

Impact of Epstein Barr Virus Infection on Treatment Opportunities in Patients with Nasopharyngeal Cancer

Chemical, physical, and infectious agents may induce carcinogenesis, and in the latter case, viruses are involved in most cases. The occurrence of virus-induced carcinogenesis is a complex process caused by an interaction across multiple genes, mainly depending by the type of the virus. Molecular mechanisms at the basis of viral carcinogenesis, mainly suggest the involvement of a dysregulation of the cell cycle. Among the virus-inducing carcinogenesis, Epstein Barr Virus (EBV) plays a major role in the development of both hematological and oncological malignancies and importantly, several lines of evidence demonstrated that nasopharyngeal carcinoma (NPC) is consistently associated with EBV infection. Cancerogenesis in NPC may be induced by the activation of different EBV "oncoproteins" which are produced during the so called "latency phase" of EBV in the host cells. Moreover, EBV presence in NPC does affect the tumor microenvironment (TME) leading to a strongly immunosuppressed status. Translational implications of the above-mentioned statements are that EBV-infected NPC cells can express proteins potentially recognized by immune cells in order to elicit a host immune response (tumor associated antigens). Three immunotherapeutic approaches have been implemented for the treatment of NPC including active, adoptive immunotherapy, and modulation of immune regulatory molecules by use of the so-called checkpoint inhibitors. In this review, we will highlight the role of EBV infection in NPC development and analyze its possible implications on therapy strategies.

EBV-associated diseases: Current therapeutics and emerging technologies

EBV is a prevalent virus, infecting >90% of the world's population. This is an oncogenic virus that causes ~200,000 cancer-related deaths annually. It is, in addition, a significant contributor to the burden of autoimmune diseases. Thus, EBV represents a significant public health burden. Upon infection, EBV remains dormant in host cells for long periods of time. However, the presence or episodic reactivation of the virus increases the risk of transforming healthy cells to malignant cells that routinely escape host immune surveillance or of producing pathogenic autoantibodies. Cancers caused by EBV display distinct molecular behaviors compared to those of the same tissue type that are not caused by EBV, presenting opportunities for targeted treatments. Despite some encouraging results from exploration of vaccines, antiviral agents and immune- and cell-based treatments, the efficacy and safety of most therapeutics remain unclear. Here, we provide an up-to-date review focusing on underlying immune and environmental mechanisms, current therapeutics and vaccines, animal models and emerging technologies to study EBV-associated diseases that may help provide insights for the development of novel effective treatments.

The Safety and Immunological Effects of rAd5-EBV-LMP2 Vaccine in Nasopharyngeal Carcinoma Patients: A Phase I Clinical Trial and Two-Year Follow-Up

Epstein-Barr virus (EBV)-encoded latent membrane protein 2 (LMP2) promotes nasopharyngeal carcinoma (NPC) progression. Previously, we reported that the dendritic cells (DCs) transfected with EBV-LMP2 recombinant serotype 5 adenoviruses (rAd5) induced anti-tumor effect by eliciting cytotoxic T lymphocytes (CTLs)-mediated immune response in vitro and the adenoviral vaccine of EBV-LMP2 (rAd5-EBV-LMP2) stimulated antigen-specific cellular immunity in mice. However, the safety and immunological effect of rAd5-EBV-LMP2 vaccine in human still remained unknown. Here we conducted a single-center, non-randomized, open-label, single-arm phase I clinical trial to clarify this unsolved issue. A total of 24 patients with regional advanced NPC were sequentially enrolled into three dose level groups (2×10(9), 2×10(10), 2×10(11) vp). The rAd5-EBV-LMP2 vaccines were intramuscularly injected for four times within 28 d (D0, D7, D14, D28). Blood samples were harvested immediately before every vaccination, one week and one month after the last vaccination (D0, D7, D14, D28, D35, D58). All the vaccine inoculation-related toxicities presented as grade I/II adverse events. The most frequent systemic adverse reactions were fatigue (33.0%, 8/24), myalgia (29.2%, 7/24) and cough (29.2%, 7/24), while the most common regional adverse reaction was tenderness in the inoculation site (54.2%, 13/24). In addition, proportion of CD(3+)CD(4+) cells in peripheral blood was significantly increased in the high dose group (2×10(11) vp). The rAd5-EBV-LMP2 vaccine was generally well-tolerated and the high dose (2×10(11) vp) is recommended to be adopted in phase II studies. The long-term outcome of rAd5-EBV-LMP2 vaccine inoculation is required to be determined in following placebo-controlled trials.

2003-2013, a valuable study: Autologous tumor lysate-pulsed dendritic cell immunotherapy with cytokine-induced killer cells improves survival in stage IV breast cancer

Dendritic cells (DCs) and cytokine-induced killer (CIK) cells have both shown activity as immunotherapy in some malignancies. Our aim was to prospective assess the effect of this immunotherapy in patients with stage IV breast cancer. Between Aug 2003 and Dec 2013, we collected 368 patients who met inclusion criteria and divided into immunotherapy group (treatment group: 188 patients) and chemotherapy group (control group: 180 patients). DCs were prepared from the mononuclear cells isolated from patients in the treatment group using IL-2/GM-CSF and were loaded with tumour antigens; CIK cells were prepared by incubating peripheral blood lymphocytes with IL-2, IFN-γ, and CD3 antibodies. After the patients had received low-dose chemotherapy, those in the treatment group also received the DC-CIK therapy, which was repeated four times in a fortnight to form one cycle. At least three cycles of DC-CIK therapy were given. Immune function was measured in treatment group patients' sera. Disease-free survival (DFS) and Overall survival (OS) after the diagnosis of stage IV breast cancer was assessed after a 10-year follow-up. The result demonstrated that immune function is obviously enhanced after DC-CIK therapy. By Cox regression analysis, DC-CIK therapy reduced the risk of disease progression (p<0.01) with an increased OS (p<0.01). After low-dose chemotherapy, active immunization with DC-CIK immunotherapy is a potentially effective approach for the control of tumour growth in stage IV breast cancer patients.

Autologous tumor lysate-pulsed dendritic cell immunotherapy with cytokine-induced killer cells improves survival in gastric and colorectal cancer patients

Gastric and colorectal cancers (GC and CRC) have poor prognosis and are resistant to chemo- and/or radiotherapy. In the present study, the prophylactic effects of dendritic cell (DC) vaccination are evaluated on disease progression and clinical benefits in a group of 54 GC and CRC patients treated with DC immunotherapy combined with cytokine-induced killer (CIK) cells after surgery with or without chemo-radiotherapy. DCs were prepared from the mononuclear cells isolated from patients using IL-2/GM-CSF and loaded with tumor antigens; CIK cells were prepared by incubating peripheral blood lymphocytes with IL-2, IFN-γ, and CD3 antibodies. The DC/CIK therapy started 3 days after low-dose chemotherapy and was repeated 3–5 times in 2 weeks as one cycle with a total of 188.3±79.8×10⁶ DCs and 58.8±22.3×10⁸ CIK cells. Cytokine levels in patients' sera before and after treatments were measured and the follow-up was conducted for 98 months to determine disease-free survival (DFS) and overall survival (OS). The results demonstrate that all cytokines tested were elevated with significantly higher levels of IFN-γ and IL-12 in both GC and CRC cohorts of DC/CIK treated patients. By Cox regression analysis, DC/CIK therapy reduced the risk of post-operative disease progression (p<0.01) with an increased OS (<0.01). These results demonstrate that in addition to chemo- and/or radiotherapy, DC/CIK immunotherapy is a potential effective approach in the control of tumor growth for post-operative GC and CRC patients.

Exploiting the interplay between innate and adaptive immunity to improve immunotherapeutic strategies for Epstein-Barr-virus-driven disorders

The recent demonstration that immunotherapeutic approaches may be clinically effective for cancer patients has renewed the interest for this strategy of intervention. In particular, clinical trials using adoptive T-cell therapies disclosed encouraging results, particularly in the context of Epstein-Barr-virus- (EBV-) related tumors. Nevertheless, the rate of complete clinical responses is still limited, thus stimulating the development of more effective therapeutic protocols. Considering the relevance of innate immunity in controlling both infections and cancers, innovative immunotherapeutic approaches should take into account also this compartment to improve clinical efficacy. Evidence accumulated so far indicates that innate immunity effectors, particularly NK cells, can be exploited with therapeutic purposes and new targets have been recently identified. We herein review the complex interactions between EBV and innate immunity and summarize the therapeutic strategies involving both adaptive and innate immune system, in the light of a fruitful integration between these immunotherapeutic modalities for a better control of EBV-driven tumors.

Immune escape by Epstein-Barr virus associated malignancies

Persistent Epstein-Barr virus (EBV) infection remains asymptomatic in the majority of virus carriers, despite the potent growth transforming potential of this virus. The increased frequency of EBV associated B cell lymphomas in immune compromised individuals suggests that tumor-free chronic infection with this virus is in part due to immune control. Here we discuss the evidence that loss of selective components of EBV specific immunity might contribute to EBV associated malignancies, like nasopharyngeal carcinoma, Burkitt's and Hodgkin's lymphoma, in otherwise immune competent patients. Furthermore, we discuss how current vaccine approaches against EBV might be able to target these selective deficiencies.

Targeting the nuclear antigen 1 of Epstein-Barr virus to the human endocytic receptor DEC-205 stimulates protective T-cell responses

Dendritic cells (DCs) express many endocytic receptors that deliver antigens for major histocompatibility class (MHC) I and II presentation to CD8(+) and CD4(+) T cells, respectively. Here, we show that targeting Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) to one of them, the human multilectin DEC-205 receptor, in the presence of the DC maturation stimulus poly(I:C), expanded EBNA1-specific CD4(+) and CD8(+) memory T cells, and these lymphocytes could control the outgrowth of autologous EBV-infected B cells in vitro. In addition, using a novel mouse model with reconstituted human immune system components, we demonstrated that vaccination with alphaDEC-205-EBNA1 antibodies primed EBNA1-specific IFN-gamma-secreting T cells and also induced anti-EBNA1 antibodies in a subset of immunized mice. Because EBNA1 is the one EBV antigen that is expressed in all proliferating cells infected with this virus, our data suggest that DEC-205 targeting should be explored as a vaccination approach against symptomatic primary EBV infection and against EBV-associated malignancies.

Dendritic cells expressing a combined PADRE/MUC4-derived polyepitope DNA vaccine induce multiple cytotoxic T-cell responses

The tumor-associated antigen, mucin4 (MUC4), is overexpressed on various epithelial malignancies, making it a potentially broadly applicable candidate vaccine therapy. In this paper, we report on the creation of a dendritic cell (DC)-based vaccine, using cells transduced with the universal DR-restricted Th helper epitope (PADRE) combined with human leukocyte antigen (HLA)-A1- and HLA-A2-restricted epitopes from MUC4 (rAd-pE-DCs). We examined this vaccine's biologic characteristics and immune activity in vitro, finding that infection with the polyepitope adenovirus did not alter the typical morphology of mature DC and the typical markers of these cells (CD86, CD83, CD80, and HLA-DR) were highly expressed on rAd-pE-DCs. Lymphocytes primed with rAd-pE-DCs generated potent cytotoxic responses. By contrast, lymphocytes primed with a GFP-expressing adenovirus (rAd-GFP-DCs) or mock-transfected DCs were not cytotoxic. Transduction of DCs with an adenovirus encoding PADRE combined with HLA-A1- and HLA-A2-restricted epitopes may be a potential strategy for the immunotherapy of MUC4-associated tumors.

Dendritic cells reconstituted with a human heparanase gene induce potent cytotoxic T-cell responses against gastric tumor cells in vitro

BACKGROUND AND AIMS

Dendritic cell-based tumor vaccination is a promising approach in the treatment of cancer. Strategies to modify dendritic cells (DCs) with tumor-associated antigens (TAAs) can elicit specific immune responses against tumors. Heparanase is overexpressed in gastric cancer, especially in invasive and metastatic cells, but is downregulated in differential normal tissue. Therefore, heparanase is a potential target in immunotherapy for patients with advanced gastric cancer who are not candidates for surgery. The present paper was designed to investigate the immune response of a heparanase gene-modified DC-based vaccine against gastric cancer cell lines in vitro.

METHODS

DCs from peripheral blood mononuclear cells of healthy HLA-A2-positive donors were transfected with recombinant adenovirus containing the full-length cDNA of heparanase (rAd-Hpa) to generate heparanase gene-modified DC vaccine. T lymphocytes from the same donors were repeatedly activated by genetically modified DC vaccine to generate heparanase-specific cytotoxicity T lymphocytes (CTLs). CTL-mediated cell lysis of gastric cancer cells lines (KATO-III and SGC-7901) was analyzed in vitro by a standard (51)Cr releasing assay. IFN-gamma secretion was measured by ELISA in heparanase-specific CTLs cocultured with those gastric cancer cell lines.

RESULTS

Our results showed that the expression of heparanase in DCs transfected with rAd-Hpa was significantly increased. Furthermore, DCs transfected with rAd-Hpa could induce heparanase-specific CTLs against HLA-matched and heparanase-positive gastric cancer cells in vitro, while there were no killing effects on autologous lymphocytes. Meanwhile, these rAd-Hpa-modified DCs could increase IFN-gamma secretion of effector cells when cocultured with KATO-III cells.

CONCLUSIONS

These findings demonstrate for the first time that the transduction of DCs with rAd-Hpa can induce CTLs that specifically lyse heparanase-positive gastric cancer cells and increase IFN-gamma secretion in an MHC-restricted fashion. Heparanase gene-modified DC vaccine offers a great opportunity for immunotherapy in patients with advanced gastric cancer and possibly also with other malignancies.