Gene-modified Tumor Cells Research Articles

822. Preclinical Efficacy Data of MGN1601, a Tumor Vaccine Comprising 4-Fold Gene-Modified and Irradiated Allogeneic Tumor Cells in Combination with a DNA-Based Immunomodulator for the Treatment of Metastatic Renal Carcinoma

822. Preclinical Efficacy Data of MGN1601, a Tumor Vaccine Comprising 4-Fold Gene-Modified and Irradiated Allogeneic Tumor Cells in Combination with a DNA-Based Immunomodulator for the Treatment of Metastatic Renal Carcinoma

Selective elimination of a chemoresistant side population of B-CLL cells by cytotoxic T lymphocytes in subjects receiving an autologous hCD40L/IL-2 tumor vaccine

Side-population (SP) analysis identifies precursor cells in normal and malignant tissues. Cells with this phenotype have increased resistance to many cytotoxic agents, and in malignant disease may represent a primary drug resistant population. To discover whether drug resistant malignant SP cells are nonetheless sensitive to immune-mediated killing, we first established the presence of a malignant CD5+CD19+ SP subset in the blood of 18/21 subjects with B-CLL. We examined the fate of these cells in 6 of these individuals who received autologous hCD40L/IL-2 gene-modified tumor cells as part of a tumor vaccine study. Vaccinated patients showed an increase in B-CLL-reactive T cells followed by a corresponding decline in circulating CD5+CD19+ SP cells. T cell lines and clones generated from vaccinated patients specifically recognized B-CLL SP tumor cells. Elimination of SP cells is likely triggered by their increased expression of target antigens such as RHAMM following stimulation of the malignant cells by hCD40L, since CD8+ RHAMM-specific T cells could be detected in the peripheral blood of immunized patients and were associated with the decline in B-CLL SP cells. Hence malignant B cells with a primary drug resistant phenotype can be targeted by T cell mediated effector activity following immunization of human subjects.

Glioma pathogenesis-related protein 1: tumor-suppressor activities and therapeutic potential.

After glioma pathogenesis-related protein 1 (GLIPR1/Glipr1) was identified, the expression of GLIPR1 was shown to be down-regulated in human prostate cancer, owing in part to methylation in the regulatory region of this gene in prostate cancer cells. Additional studies showed that GLIPR1/Glipr1 expression is induced by DNA-damaging agents independent of p53. Functional analysis of GLIPR1 using in vitro and in vivo gene-transfer approaches revealed both growth suppression and proapoptotic activities for mouse Glipr1 and human GLIPR1 in multiple cancer cell lines. The proapoptotic activities were dependent on production of reactive oxygen species and sustained c-Jun-NH2 kinase signaling. It was interesting that adenoviral vector-mediated Glipr1 (AdGlipr1) transduction into prostate cancer tissues using an immunocompetent orthotopic mouse model revealed additional biologic activities consistent with tumor-suppressor functions. Significantly reduced tumor-associated angiogenesis and direct suppression of endothelial-cell sprouting activities were documented. In addition, AdGlipr1 strongly stimulated antitumor immune responses that resulted in specific cytotoxic T-lymphocyte activities in this model. Glipr1-related antitumor immunostimulatory activities were confirmed and extended in subsequent studies. Administration of a novel Glipr1 gene-modified tumor cell vaccine had significant antitumor activity in a mouse model of recurrent prostate cancer. In conclusion, restoration of GLIPR1 function in prostate cancer cells through GLIPR1 gene-based or GLIPR protein-based delivery methods may provide a safe and effective approach for targeted therapy for a range of malignancies.

Human survivin modified DCs vaccine inhibits laryngeal cancer in vivo and in vitro

Construction of human full-length survivin gene-modified DCs vaccine and observe the biological characteristics and the role of laryngeal cancer treatment. Construction of homologous recombination through the full-length survivin-human adenovirus (pAd-sur), and transfection of immature DCs, induced by access to sophisticated cultivate DCs, the proliferation of activated T lymphocytes; DCs vaccine different groups observed in vitro, in vivo biological activity. The success in bringing human to build a full-length survivin gene recombinant adenovirus vector pAd-sur; get with the typical characteristics of DCs, the expression level of the surface molecules of up to CD1a 46.2%, CD80 64.2%, CD83 80.5%, HLA-DR 84.3%, vaccine for in vitro cell killing rate 51.5%, compared with the control group, the difference was significant (t = 7.1358, P < 0.01). Gene-modified tumor cell vaccine group was 54.9% of apoptosis and necrosis rate of 21.9%, compared with the control group, the difference was significant (t value was 33.0209 and 17.5057, all P < 0.01). Human full-length survivin gene modified, DCs The expression of surface molecules than the rate of gene-modified DCs without a significant increase, with more to stimulate T lymphocyte proliferation, and promote secretion of gamma-IFN; in vivo, in vitro to promote the ability of anti-laryngeal cancer cells.

Cytokine gene‐mediated immunotherapy: Current status and future perspectives

Recent understanding of the molecular events crucial in overcoming immunosuppressive tumor microenvironments and generating effective antitumor immunity provides us with the wreath opportunity to manipulate genes that have a key role in antitumor immune responses. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-12 (IL-12) are two indispensable cytokines for activating dendritic cells and boosting the strong immune responses against cancer. In this review, we describe the antitumor mechanisms and clinical application of gene-modified tumor cells and dendritic cells to secrete GM-CSF or IL-12, respectively, in various preclinical and clinical settings. The principles operative in these vaccination strategies may prove applicable to other immunotherapy strategies, especially in combination with other therapeutic modalities, such as chemotherapy and targeted therapy.

Editorial Comment on: Vaccine Therapy in Patients with Renal Cell Carcinoma

antigens have been identified, which has led to the testing of cell–based tumor vaccines. Approaches have included gene-modified tumor cells and dendritic cell–based vaccines [1]. Most of these approaches, however, failed to demonstrate significant efficacy in randomized phase 3 trials. The single exception was Reniale, a patient-specific vaccine using lysates from autologous tumors cells extracted at the time of surgery. Although promising results were reported with Reniale, questions arose regarding the study design [2]. There are plans to conduct an international phase 3 trial to confirm these results, which will hopefully lead to regulatory approval for the product. As Van Poppel et al [3] describe in their review article, there have been a number of phase 3 clinical trial failures in the field of RCC. What explains these failures [4,5]? Some vaccines (eg, Oncophage) may have low potency to induce specific T-cell responses, resulting in controlling patients with only small-volume disease. The pivotal clinical trial of Oncophage showed improvement in the unplanned analysis of earlier stage patients but not in the overall patient population. Other vaccines (like Trovax) use single-cancer antigens that may facilitate treatment escape through downregulation or total expression loss. Additionally, in the Trovax trial, problems in the design, like the use of adjuvant alone in the control arm, could also have skewed the statistical power. Finally, the development decisions of a vaccine program need to be based on clinical data, not just on immune response (eg, with Vitespen, for which rare objective regressions of metastatic disease were seen). Immune responses have not been predictive of clinical benefit. The rare vaccines that do generate brisk B-cell or T-cell responses, for example, apparently do not induce the correct effector functions to reject tumors or to overcome immunosuppression. As stated by Van Poppel et al [3], the success of clinical effectiveness in selected populations combined with more potent vaccines with novel adjuvants and strategies aimed at circumventing tumor-associated immunosuppression [4] may improve the efficacy of tumor vaccines and cellular immunotherapy so that they live up to their promise.

Isolation and properties of gene-modified mouse bcr-abl-transformed cells expressing various immunostimulatory factors

B210 cells are murine (BALB/c) cells transformed by bcr-abl fusion gene. After intravenous administration they are capable of inducing leukaemia-like disease in syngeneic mice. From these cells a thymidine-kinase less subline was derived. It was significantly less pathogenic than the parental cells. However, a highly pathogenic clone denoted B210cTK-/cl-2 was isolated from its population. As determined by Western blotting, these cells produced more p210 protein than the parental B210 cells. To successfully transfect these cells a modified electroporation method was introduced. Bicistronic plasmids carrying gene for herpes simplex thymidine kinase (HSV TK) and the gene for either granulocyte-monocyte colony stimulation factor (GM-CSF), interleukin-2 (IL-2) or interleukin 12 (IL-12) were used for the transfection experiments. Gradually, cell lines producing these cytokines were isolated in media supplemented with hypoxantin, aminopterin and thymidine (HAT). All of them were highly sensitive to ganciclovir in vitro confirming that the cells produced HSV TK. The genetic modification of B210cTK-/cl-2 was associated neither with the alteration of p210 bcr-abl production nor with any changes in expression of MHC class I molecules. From populations of each of the three lines several cell clones were isolated and tested for the production of the respective cytokines. The original uncloned population and several clones differing in the cytokine production were administered intravenously into mice. All animals survived without symptoms of the disease suggesting that the gene-modification was associated with the loss of pathogenicity. CML, Bcr-Abl, HSV TK, cytokines, gene-modified tumour cells, pathogenicity.

A study on anti-tumor immunity induced by gene-modified melanoma B16 cells

T cell-mediated cell immunity is the main anti-tumor immunity in which the effector T cells need specific antigen and costimulatory signals. One of the vaccines applied in tumor immunotherapy is the gene-modified tumor cell vaccine. One potential method to increase cell epitope density is to link the antigen with the major histcompatibility complex subunit beta2m. Our previous research indicated that the strategy of epitope fusion gene OVA-linker-beta2m can promote the formation of specific compounds on the tumor cell surface in vitro. In this study, we constructed two coexpression vectors pGL3-CD80-OVA-linker-beta2m and pGL3-IL21-OVA-linker-beta2m, in order to explore the cooperative action of CD80 or interleukin-21 (IL21) with the epitope fusion gene in anti-tumor immunity. Results showed that gene-modified B16 cells (B16/OVA, B16/CD80-OVA and B16/IL21-OVA) grew slower than B16 cells in vitro and in vivo, especially the B16/IL21-OVA subline, which illustrated that such gene modification decreased oncogenicity of malignant tumor cells. On the other hand, gene-modified tumor cell subline immunization can induce effective long-term anti-tumor immunity defending tumor cell attacks. IL21 played a more cooperative role with the OVA-linker-beta2m than CD80 in this study. This strategy might lay foundations for the research of a new type of tumor vaccine.

Immunotherapy for Renal Cell Carcinoma

Since spontaneous regression of metastatic renal cell carcinoma (mRCC) has been reported, immunotherapy for mRCC has been the therapeutic option. The goal of modulating an immune response to the tumor cell with passive and/or active immunotherapy can be achieved through the increasing technological sophistication and the understanding of the immune system. Currently, among the several available cytokines to treat mRCC, high-dose interleukin-2 (IL-2) administration is the only way to obtain complete remission. However, due to the lack of prominent benefit and toxicity of high dose IL-2 therapy, cytokine-based immunotherapy for the treatment of mRCC is threatened by the intriguing molecularly targeted agents, which are still under the trials. Different types of cellular (autologous tumor cell, gene modified tumor cell, dendritic cell) and non-cellular therapeutic vaccines of mRCC have been applied in the clinical setting, and the success of clinical effectiveness in selected population has been reported. Future treatment approaches for mRCC or locally advanced RCC would be directed with combined therapy with immunotherapy and targeted agent. Additionally, molecularly targeted agents and vaccines modulating tumor immunology cascade will be another immunotherapeutic approach for RCC.

Synergistic antitumor effect of chemotactic-prostate tumor-associated antigen gene-modified tumor cell vaccine and anti-CTLA-4 mAb in murine tumor model

In this study, we demonstrate that an effective immune response against prostate tumors in mouse tumor model can be elicited using a strategy that combines CTLA-4 blockade and pSLC-3P-Fc-modified tumor cell vaccine (named B16F10-SLC-3P-Fc). Treatment of B16F10-3P-bearing mice resulted in a significant reduction in tumor incidence as assessed 2 months after treatment. In vivo Ab depletion confirmed that the antitumor effect was primarily CD8 + T cells and CD4 + T lymphocytes were required for the induction of CD8 + CTL response in B16F10-SLC-3P-Fc + anti-CTLA-4 mAb-immunized mice. Moreover, mice that were cured of an established tumor were protected against a rechallenge with the same tumor for at least 4 months, suggesting the generation of memory responses. Adoptive transfer experiments further indicate that antitumor reactivity can be transferred to naïve mice by splenocytes. These findings demonstrate that this combinatorial treatment can elicit a potent anti-tumor immune response and suggest potential of this approach for treatment of prostate cancer.

HLA-A0201-positive, IL-7/B7.1-cotransfected allogeneic tumor cells as a vaccine in metastatic renal cell cancer—A clinical phase-I trial

3072 Background: Tumor vaccination remains a promising experimental approach in RCC. HLA-A0201-restricted T cell immunity against RCC is well established. RCC26 is an allogeneic HLA-A0201+ human RCC cell line, a T cell clone specifically recognising RCC26 and other RCC in the context of HLA-A0201 has previously been generated, the TCR of this T cell clone was characterised. Furthermore, IL-7/B7.1 cotransfected tumor cells are a potent vaccine in animal models. Methods: RCC26 was transfected with pKEx-IL-7-IR-B7 coding for human IL-7 and B7.1 (CD80). 10 HLA-A0201+ patients with metastatic RCC and disease progression under cytokine therapy were included. 10 vaccinations with 2.5–40x106 gene-modified irradiated tumor cells which had been produced under GMP conditions were performed s.c. over 22 weeks. Primary endpoints of the study were feasibility, safety and immunological response, secondary endpoint was clinical response. The protocol was approved by the ethics committee, all patients gave informed consent. Results: Gene-modified RCC26 cells produced IL-7 (3.4 ng/106 cells/24h), more than 90% of the cells were CD80+. Vaccination was feasible and safe with no severe toxicity. Local DTH-reactions were observed in 4 patients. Skin biopsies of the vaccination site showed lymphocytic infiltrates dominated by CD4+T cells. In 8 patients vaccination induced HLA- and /or antinuclear antibodies without clinical signs of autoimmunity. Analysis of the T cell response against RCC-associated antigens is under way. No partial or complete responses could be documented. However, 50% of the patients had stable disease with the longest TTP being 69 weeks. Mean TTP in our cohort was 25 weeks (range 4 to 69 weeks). Conclusion: Our results show that vaccination with an allogeneic gene-modified tumor cell line is feasible and safe. Stable disease lasting up to 69 weeks in a substantial proportion of patients suggests immunological activity of the vaccine. Vaccination of patients with a low tumor burden is a promising strategy for the future, i.e. after surgery or treatment with novel multi-kinase inhibitors. No significant financial relationships to disclose.

Therapeutic effect of IL-12 gene modified tumor cell vaccine on transplanted intraocular melanoma in mice

目的 观察白细胞介素12(IL-12)基因修饰瘤苗对移植性黑色素瘤的疗效.方法 将荷瘤模型鼠分为PBS治疗组,野生型肿瘤细胞疫苗(WTV)治疗组,IL-12基因修饰肿瘤细胞疫苗(GTV)治疗组.模型建立后的第3 d、10 d分别在各组鼠结膜下注射30 μl PBS、30 μl(3.0×106个细胞)灭活的WTV及GTV,观察角膜溃破时间、淋巴结和肺的转移率及生存时间.结果 PBS组及WTV组角膜溃破时间早于GTV组,前两组间差异无统计学意义;模型建立后的第18 d,GTV组淋巴结转移瘤发生率低于PBS组及WTV组,后两组间差异无统计学意义;模型建立后第28 d的各组间小鼠肺转移瘤发生率及各组间小鼠生存时间均无统计学意义.结论 IL-12基因修饰瘤苗对实验模型鼠荷瘤早期起到了一定的抗肿瘤效应。

Increased induction of antitumor response by exosomes derived from interleukin-2 gene-modified tumor cells

Tumor-derived exosomes (TEX) have been proposed as a new kind of cancer vaccine; however, their in vivo antitumor effects are not satisfactory. In order to further improve the efficacy of vaccination with TEX, we investigated whether interleukin-2 (IL-2) genetic modification of tumor cells can make IL-2 presence in the exosomes, thus increasing antitumor effects of the TEX. E.G7-OVA tumor cells expressing Ovalbumin (OVA) as a tumor model antigen were used to prepare TEX by serial centrifugation and sucrose gradients ultracentrifugation. To demonstrate their antitumor effects, IL-2-containing exosomes (Exo/IL-2) were injected subcutaneously into C57BL/C mice: either bearing tumor or followed by tumor inoculation. We found IL-2 within those exosomes as detected by both ELISA and Western blot. Vaccination with these Exo/IL-2 could induce antigen-specific Th1-polarized immune response and Cytotoxic T lymphocytes (CTL) more efficiently, resulting in more significant inhibition of tumor growth. CD8(+) T cells are the main effector cells, however, CD4(+) T cells, and NK cells are also involved in the induction of antitumor response of this approach. Our results demonstrate that IL-2 genetic modification of tumor cells can make the TEX contain IL-2 with the increased antitumor effects, representing a promising way of exosome-based tumor vaccine.

Therapeutic Vaccine for Lymphoma

The unique antigenic determinants (Idiotype [Id]) of the immunoglobulin expressed on a given B-cell malignancy can serve as a tumor-specific antigen for active immunotherapy. Therapeutic vaccines targeting the tumor-specific idiotype have demonstrated promising results against lymphomas in phase I/II studies and are currently being evaluated in phase III randomized trials. Additional vaccine therapies being developed include those based on DNA, dendritic cells, gene-modified tumor cells. It is hoped that immunotherapeutic agents, used in tandem or in combination, may in the future allow effective treatment of lymphoid malignancies and delay or even replace the need for conventional cytotoxic therapies.

Potent Systemic Antitumor Immunity Induced by Vaccination with Chemotactic-Prostate Tumor Associated Antigen Gene-Modified Tumor Cell and Blockade of B7-H1

We previously reported that several DNA fragments from human prostate-specific membrane antigen (hPSM), mouse prostatic acid phosphatase (mPAP), and human prostate-specific antigen (hPSA) genes were selected and fused to create a novel hPSM-mPAP-hPSA fusion gene (named 3P gene), and human secondary lymphoid tissue chemokine (SLC), 3P, and human IgG Fc genes were inserted into pcDNA3.1 to construct a DNA vaccine, designated pSLC-3P-Fc. In this report, to establish a more efficient treatment for immunotherapy against prostate cancer, the construct was transfected into B16F10 to generate gene-modified tumor cell vaccine (named B16F10-SLC-3P-Fc). In poorly immunogenic B16F10 mouse melanoma model, the immunization with B16F10-SLC-3P-Fc resulted in a strong antitumor response and 50% of tumor-bearing mice achieved long-term survival (>120 days). In vivo depletion of lymphocytes indicated that CD8(+) T cells were involved in the direct tumor killing, whereas CD4(+) T lymphocytes were required for the induction of CD8(+) CTL response in B16F10-SLC-3P-Fc-immunized mice. Splenocytes from B16F10-SLC-3P-Fc-immunized mice specifically recognized and lysed PSM, PAP, PSA, and 3P expressing tumor cells. The combined therapy of B16F10-SLC-3P-Fc plus anti-B7-H1 MAbs further enhanced the immune response. Rechallenge experiment showed that a persistent memory response was successfully induced by the combined therapy. These observations suggest pSLC-3P-Fc-modified tumor cells could serve as a vaccine against prostate cancer, and the therapy combined with anti-B7-H1 MAbs further enhanced the antitumor immune response.

Immune Responses Are Induced Against Side-Population B-CLL “Stem Cells ” by Patient Vaccination with hCD40L/IL2 Gene Modified Tumor Cells.

An apparent stem cell population can be identified in many normal and malignant tissues by their side-population (SP) phenotype, characterized by a high level of Hoechst dye efflux. Malignant SP cells have increased resistance to many cytotoxic drugs and may contribute to relapse and disease progression. We have looked for SP cells in patients with B cell chronic lymphocytic leukemia (B-CLL) and determined whether these cells could be targeted by an immune response after immunization with hCD40L/IL2 gene modified tumor vaccines. We also assessed the impact of any anti-SP immune response on overall disease. For SP analysis, PBMC containing >90% CD5+CD19+ cells were obtained pre-treatment. We incubated the cells with 5mg/ml Hoechst 33342 dye for 2 hours at 37°C. Cells were then labeled with CD5, CD19 and propidium iodide and sorted by flow cytometry into SP and non-SP populations. 11 of 12 patient tumor samples contained a distinct CD5+CD19+ SP population (0.04%–2%), whereas SP were undetectable in PBMC from healthy donors. SP cells had increased gene expression compared to non-SP for ABCG2 (4±2-fold) and the “stemness” genes p21cip1/waf1 (8±12-fold) and Bmi-1 (12±21-fold) supporting their function as a precursor population for the bulk of tumor cells. In 5 of the patients, SP analysis was done on samples taken before, during and after receiving tumor vaccines. We observed a significant decrease (p< 0.05) in B-CLL SP cells in all 5, although in 4/5, the decrease was transient, returning to pre-treatment levels by 4 months post-immunization. To determine if the observed reduction in tumor SP was associated with an immune response to these cells, B-CLL-specific cytotoxic T lymphocytes (CTL) were generated from T cells during immunization (2–4 weeks). These CTLs were specific for autologous bulk B-CLL cells (week 2 CTL, 40±4 IFN-gamma spot forming units (SFU) versus unstimulated controls 20±12 SFU, rising to 334±14 SFU versus control 20±5 SFU by week 4, P<0.01). Moreover, CTL lines obtained at 4 weeks after immunization were highly reactive against SP B-CLL cells. To determine the effects of the induced anti-B-CLL SP reactivity on the patients' disease, we followed the 5 patients for >1 year. In the 4 individuals in whom the anti-SP cell response was transient, no sustained effect on disease burden was evident. In one patient, however, the tumor SP cells remained at undetectable levels after immunization. This individual subsequently had a delayed (from 6 months onwards) but progressive disease response, and by 15 months had resolution of lymphadenopathy, a reduction in splenomegaly and a >90% decrease in the circulating B-CLL count. Hence, B-CLL cells contain a primitive side-population, which can be targeted by an immune response after immunization with autologous CD40L and IL2 expressing tumor cells. A sustained anti-B-CLL SP response was associated with a delayed but progressive response in the bulk tumor population. This effect is consistent with “stem cell” activity in the SP of B-CLL, and suggests that tumor SP cells may be an important target for therapy.

Enhanced induction of dendritic cell maturation and HLA-A*0201-restricted CEA-specific CD8+ CTL response by exosomes derived from IL-18 gene-modified CEA-positive tumor cells

Dendritic cells (DC)-derived or tumor-derived exosomes are a population of nanometer sized membrane vesicles that can induce specific anti-tumor immunity. However, the immunogenic potential and efficiency of exosomes-based tumor vaccine are not satisfactory enough to achieve a curative effect in clinical trials. In this article we investigated whether IL-18 genetic modification of tumor cells can increase the efficacy of exosomes derived from IL-18 gene-modified tumor cells. We transfected carcinoembryonic antigen (CEA)-expressing tumor cells with a recombinant adenovirus encoding human IL-18 (AdhIL-18) and prepared the exosomes, Exo/IL-18, from IL-18 gene-modified tumor cells. We found that Exo/IL-18 naturally contain CEA and bioactive IL-18. Moreover, Exo-IL-18 are potent in chemoattracting DC and T cells, enhancing the proliferation and Th1 cytokine release of PBMC, and promoting the phenotypic and functional maturation of DC. Furthermore, Exo/IL-18-pulsed DC are quite potent to induce HLA-A*0201-restricted, CEA-specific CD8+ CTL from the PBMC of HLA-A*0201 CEA+ cancer patients in vitro. In almost all of these experiments, Exo/IL-18 show more potent functions than the conventionally prepared exosomes derived from parent tumor cells without IL-18 gene modification. Our findings suggest that Exo/IL-18 has more potent capability to induce specific anti-tumor immunity, and our strategy of IL-18 modification of exosomes is a feasible approach to develop exosomes-based tumor vaccines.

630. A Phase 2 Randomized Study of GM-CSF Gene-Modified Autologous Tumor Cell Immunotherapy (CG8123) with and without Low- Dose Cyclophosphamide in Advanced Stage Non- Small Cell Lung Cancer (NSCLC)

A previous trial of autologous GVAX® immunotherapy for lung cancer in NSCLC yielded successful product manufacturing in 81% of patients enrolled and demonstrated complete tumor responses in 3 of 33 advanced stage patients treated (Nemunaitis, JNCI 2004;96:326–31). A novel closed cell processing system was developed which shortens the process time to one day. We initiated a phase 2 trial with this modified manufacturing process in stage IIIB/IV NSCLC. Patients with successful product manufacturing were randomized to immunotherapy alone (every 2 wks × 5; cohort A) vs.

Vaccination with IFN-inducible T cell α chemoattractant (ITAC) gene-modified tumor cell attenuates disseminated metastases of circulating tumor cells

Immunotherapeutic strategies for metastatic diseases are being developed. IFN-inducible T cell α chemoattractant (ITAC) has been demonstrated to be able to induce Th1-type immune response. However, the effects of ITAC on the tumor metastasis have not been fully understood. In the present study, the ITAC-modified tumor cell vaccine in inhibiting the disseminated pulmonary metastasis was evaluated. ITAC-modified tumor cell vaccine 4T1-ITAC was developed by stably transfecting 4T1 cells with pcDNA3-ITAC plasmid. Mice were vaccinated with 4T1-ITAC. Mice vaccinated with 4T1-pcDNA3 and 4T1 were used as controls. Specific cellular immune responses against 4T1 were tested by in vitro proliferation, cytokine production and cytotoxic assay. The number of clonogenic metastatic tumor cells and metastatic forci on the surface of lung were counted by histological examination. Results showed that a significant enhancement of proliferative and cytotoxic activities accompanied with increased IFN-γ and TNF-α production as well as decreased IL-4 production were obtained from the mice vaccinated with 4T1-ITAC. The number of clonogenic metastatic tumor cells in the mice vaccinated with 4T1-ITAC cells reduced markedly and no visible metastasis was found in the lungs of the 4T1-ITAC vaccinated mice. Consequently, the survival rate was dramatically increased in these mice. Taken together, our results demonstrated that ITAC-modified tumor cell vaccine can enhance the anti-tumor immunity and reduce the incidence of disseminated metastasis.

Fusion Hybrid of Dendritic Cells and Engineered Tumor Cells Expressing Interleukin-12 Induces Type 1 Immune Responses against Tumor

Dendritic cell (DC)-tumor fusion hybrid vaccinees that facilitate antigen presentation represent a novel powerful strategy in cancer immunotherapy. Preclinical studies have demonstrated that IL-12 promotes specific antitumor immunity mediated by T cells in several types of tumors. In the present study, we investigated the antitumor immunity derived from vaccination of fusion hybrids between DCs and engineered J558/IL-12 myeloma cells secreting Th1 cytokine IL-12. The expression vector pcDNA-IL-12 was generated and transfected into J558 myeloma cells and then bone marrow-derived DCs were fused with engineered J558/IL-12 cells. The antitumor immunity derived from vaccination of the fusion hybrid DC/J558/IL-12 was evaluated in vitro and in vivo. DC/J558/IL-12 cells secreted recombinant IL-12 (1.6 ng/mL), and inoculation of BALB/c mice with DC/J558/IL-12 hybrid induced a Th1 dominant immune response and resulted in tumor regression. Immunization of mice with engineered DC/J558/IL-12 hybrid elicited stronger J558 tumor-specific cytotoxic T lymphocyte (CTL) responses in vitro as well as more potent protective immunity against J558 tumor challenge in vivo than immunization with the mixture of DCs and J558/IL-12, J558/IL-12 and J558, respectively. Furthermore, the anti-tumor immunity mediated by DC/J558/IL-12 tumor cell vaccination in vivo appeared to be dependent on CD8+ CTL. These results demonstrate that the engineered fusion hybrid vaccines that combine Th1 cytokine gene-modified tumor cells with DCs may be an attractive strategy for cancer immunotherapy.