Antigen-loaded Dendritic Cells Research Articles

Design of TOLERANT: phase I/II safety assessment of intranodal administration of HSP70/mB29a self-peptide antigen-loaded autologous tolerogenic dendritic cells in patients with rheumatoid arthritis

IntroductionIn rheumatoid arthritis (RA), immunosuppressive therapies may achieve symptomatic relief, but do not induce long-term, drug-free remission. Meanwhile, the lifelong use of immunosuppressive drugs confers increased risk for malignancy and...

A pilot study of multi-antigen stimulated cell therapy-I plus camrelizumab and apatinib in patients with advanced bone and soft-tissue sarcomas

BackgroundCell-based immunotherapy shows the therapeutic potential in sarcomas, in addition to angiogenesis-targeted tyrosine kinase inhibitor (TKI) and immune checkpoint inhibitor (ICI). Multi-antigen stimulated cell therapy-I (MASCT-I) technology is a sequential immune cell therapy for cancer, which composes of multiple antigen-loaded dendritic cell (DC) vaccines followed by the adoptive transfer of anti-tumor effector T-cells.MethodsIn this phase 1 study, we assessed MASCT-I plus camrelizumab (an ICI against PD-1) and apatinib (a highly selective TKI targeting VEGFR2) in patients with unresectable recurrent or metastatic bone and soft-tissue sarcoma after at least one line of prior systemic therapy. One MASCT-I course consisted of 3 DC subcutaneous injections, followed by 3 active T cell infusions administered 18–27 days after each DC injection. In schedule-I group, 3 DC injections were administered with a 28-day interval in all courses; in schedule-II group, 3 DC injections were administered with a 7-day interval in the first course and with a 28-day interval thereafter. All patients received intravenous camrelizumab 200 mg every 3 weeks and oral apatinib 250 mg daily.ResultsFrom October 30, 2019, to August 12, 2021, 19 patients were enrolled and randomly assigned to schedule-I group (n = 9) and schedule-II group (n = 10). Of the 19 patients, 11 (57.9%) experienced grade 3 or 4 treatment-related adverse events. No treatment-related deaths occurred. Patients in schedule-II group showed similar objective response rate (ORR) with those in schedule-I group (30.0% versus 33.3%) but had higher disease control rate (DCR; 90.0% versus 44.4%) and longer median progression-free survival (PFS; 7.7 versus 4.0 months). For the 13 patients with soft-tissue sarcomas, the ORR was 30.8%, DCR was 76.9%, and median PFS was 12.9 months; for the 6 patients with osteosarcomas, the ORR was 33.3%, the DCR was 50.0%, and median PFS was 5.7 months.ConclusionsOverall, MASCT-I plus camrelizumab and apatinib was safe and showed encouraging efficacy in advanced bone and soft-tissue sarcoma, and schedule-II administration method was recommended.Trial registrationClinicalTrials.gov, NCT04074564.

Enhanced TLR5-denpendent migration and activation of antigen-loaded airway dendritic cells by flagellin.

Toll-like receptor 5 (TLR5) agonist flagellin is an effective mucosal adjuvant via intranasal (i.n.) administration. Previous studies demonstrated that the mucosal adjuvanticity of flagellin depends on TLR5 signaling of airway epithelial cells. Since dendritic cells (DCs) play a central role in antigen sensitization and the initiation of primary immune responses, we wondered how DCs were modulated by the intranasally administrated flagellin. In this study, a mouse model of i.n. immunization with ovalbumin (OVA), a model antigen, in the presence or absence of flagellin was utilized. We found that nasal administration of flagellin enhanced the coadministered antigen specific antibody responses, and T cell clonal expansion in a TLR5-dependent manner. However, neither the entering of flagellin to nasal lamina propria, nor the uptake of coadministered antigen by nasal resident DCs was associated with TLR5 signaling. In contrary, migration of antigen-loaded DCs from the nasal cavity to the cervical lymph nodes (CLN) and activation of DC in the CLN were both enhanced through TLR5 signaling. Furthermore, for the DCs, flagellin enhanced the expression of CCR7, which was pivotal for DCs in the priming site migrating to draining lymph nodes. Interestingly, the migration, activation and chemokine receptor expression levels of antigen-loaded DC were all significantly higher than that of bystander DCs. In conclusion, intranasally administrated flagellin enhanced TLR5-dependent antigen loaded DCs' migration and activation, but not antigen uptake.

Anti-TNFR2 enhanced the antitumor activity of a new HMGN1/3M-052 stimulated dendritic cell vaccine in a mouse model of colon cancer

Immunotherapy is the new approach for cancer treatment that can be achieved through several strategies, one of which is dendritic cells (DCs) vaccine therapy. However, traditional DC vaccination lacks accurate targeting, so DC vaccine preparation needs to be optimized. Immunosuppressive CD4+Foxp3+ regulatory T cells (Tregs) in the tumor microenvironment can promote tumor immune escape. Therefore, targeting Tregs has become a strategy for tumor immunotherapy. In this study, we found that HMGN1 (N1, a dendritic cell-activating TLR4 agonist) and 3M-052 (a newly synthesized TLR7/8 agonist) synergistically stimulate DCs maturation and increase the production of proinflammatory cytokines TNFα and IL-12. In a colon cancer mice model, vaccination with N1 and 3M-052 stimulated and tumor antigen-loaded DCs combined with anti-TNFR2 inhibited tumor growth in mice, and the antitumor effect was mainly achieved through stimulation of cytotoxic CD8 T cell activation and depletion of Tregs. Overall, the combinating of DC activation by N1 and 3M-052 with inhibition of Tregs by antagonizing TNFR2 as a therapeutic strategy may represent a more effective strategy for cancer treatment.

Research progress of neoantigen-based dendritic cell vaccines in pancreatic cancer.

The mutation of the crucial genes such as tumor suppressors or oncogenes plays an important role in the initiation and development of tumors. The non-synonymous mutations in the tumor cell genome will produce non-autologous proteins (neoantigen) to activate the immune system by activating CD4+ and CD8+ T cells. Neoantigen-based peptide vaccines have exhibited exciting therapeutic effects in treating various cancers alone or in combination with other therapeutic strategies. Furthermore, antigen-loaded DC vaccines are more powerful in inducing stronger immune responses than vaccines generated by antigens and adjuvants. Therefore, neoantigen-based dendritic cell (DC) vaccines could achieve promising effects in combating some malignant tumors. In this review, we summarized and discussed the recent research progresses of the neoantigen, neoantigen-based vaccines, and DC-based vaccine in pancreatic cancers (PCs). The combination of the neoantigen and DC-based vaccine in PC was also highlighted. Therefore, our work will provide more detailed evidence and novel opinions to promote the development of a personalized neoantigen-based DC vaccine for PC.

Activated T cell therapy targeting glioblastoma cancer stem cells

Naïve T cells become effector T cells following stimulation by antigen-loaded dendritic cells (DCs) and sequential cytokine activation. We aimed to develop procedures to efficiently activate T cells with tumor-associated antigens (TAAs) to glioblastoma (GBM) stem cells. To remove antigen presentation outside of the immunosuppressive tumor milieu, three different glioma stem cell (GSC) specific antigen sources to load DCs were compared in their ability to stimulate lymphocytes. An activated T cell (ATC) protocol including cytokine activation and expansion in culture to target GSCs was generated and optimized for a planned phase I clinical trial. We compared three different antigen-loading methods on DCs to effectively activate T cells, which were GBM patient-derived GSC-lysate, acid-eluate of GSCs and synthetic peptides derived from proteins expressed in GSCs. DCs derived from HLA-A2 positive blood sample were loaded with TAAs. Autologous T cells were activated by co-culturing with loaded DCs. Efficiency and cytotoxicity of ATCs were evaluated by targeting TAA-pulsed DCs or T2 cells, GSCs, or autologous PHA-blasts. Characteristics of ATCs were evaluated by Flow Cytometry and ELISpot assay, which showed increased number of ATCs secreting IFN-γ targeting GSCs as compared with non-activated T cells and unloaded target cells. Neither GSC-lysate nor acid-eluate loading showed enhancement in response of ATCs but the synthetic peptide pool showed significantly increased IFN-γ secretion and increased cytotoxicity towards target cells. These results demonstrate that ATCs activated using a TAA synthetic peptide pool efficiently enhance cytotoxicity specifically to target cells including GSC.

CRISPR-Cas9 genetic screening approaches to uncover machinery involved in cross-presentation

Antigen cross-presentation is a critical process involved in the initiation of anti-viral and anti-tumour immunity. During cross-presentation, exogenous antigens are captured by dendritic cells (DCs), imported into the cytosol, and processed by proteasome for presentation on MHC class I. Our goal is to identify genes required for cross-presentation using CRISPR-Cas9 screening approaches. In order to perform pooled genetic screens, we established a range of novel assays to monitor antigen cross-presentation in single cells. To identify individual cross-presenting cells, we developed a method where cell:cell conjugates between antigen-loaded DCs and naive T cells are isolated using flow cytometry. To identify genes involved in antigen import into the cytosol specifically, we used saporin as model antigen and performed puromycin-labelling of nascent polypeptides to monitor saporin import into the cytosol and the resulting arrest in translation. As a proof of concept, we applied these assays to a heterogenous population of splenocytes and discovered that, in addition to DCs, splenic red pulp macrophages (RPMs) are also efficient in antigen import and cross-presentation. We then employed these methods in CRISPR-Cas9 pooled screens using a cDC1 cell line, MutuDCs and a custom sgRNA library targetting genes highly expressed in cross-presenting cells. We are now further characterising the hits with the overall goal to improve our understanding of mechanistic details underlying cross-presentation.

Triiodothyronine-stimulated dendritic cell vaccination boosts antitumor immunity against murine colon cancer

Given the ability of dendritic cells (DCs) to modulate other immune players, their manipulation holds great potential for inducing efficient antitumor immunity. However, DC vaccine manufacturing deserve optimization since tumor cell cargo and DC functional state induced by maturation signals influence their in vivo immunogenic potential. We reported that triiodothyronine (T3) stimulates mice DCs’ maturation and their ability to promote pro-inflammatory and cytotoxic T-cell responses. This study aimed to evaluate the efficacy of T3-conditioned DC vaccination in a murine model of colon carcinoma, deciphering the molecular players involved; and to examine the effects of T3 on the maturation and activation of human DCs (huDCs). Bone marrow-derived DCs were exposed to T3 and MC38 cancer cells that underwent cell death (MC38-Apo/Nec) by UVB irradiation. Our results showed that MC38-Apo/Nec cells are efficiently uptaken by DCs and that T3 upregulates CD86 expression with increased production of the pro-inflammatory cytokines IL-12, IL-6 and TGF-β. In a colon cancer model, vaccination with T3-stimulated and tumor antigen-loaded DCs inhibited tumor growth in wild type mice, an effect that was eliminated in IL-17-deficient animals. Notably, secretion of high levels of IFN-γ and IL-17, induction of Th1, Th17 and tumor-specific cytotoxic T lymphocytes characterized the antitumor response upon vaccination. Moreover, our initial findings demonstrated a significant increase in CD86 expression and IL-12 production by huDCs induced by T3. Overall, these results reinforce the adjuvant properties of T3-conditioned DCs to potentiate T-cell-mediated antitumor immunity and support promising advances in the translation process to human oncotherapy.

Lung-resident memory CD4 T cells recognizing antigen in the airway enhance the kinetics of antigen presentation and naive T cell activation in draining lymph nodes

Abstract CD4+ tissue-resident memory (TRM) T cells act as sentinels at previous sites of infection and rapidly initiate protective inflammatory responses upon antigen re-encounter. Here, we tested if beyond local impacts in the lung, TRM responses lead to faster egress of antigen-loaded dendritic cells (DC) resulting in their more rapid accumulation in draining lymph nodes (DLN). To do so, we used a mouse model originally developed to examine CD4+ TRM-mediated protection against influenza virus infection. We established a TRM population in otherwise naïve mice by intranasal transfer of memory CD4 T cells specific for ovalbumin (OVA). The mice were then challenged with fluorescently-labelled OVA protein intranasally. Faster migration from the lung to the DLN by OVA+ DC was seen within 48 hours of protein administration in mice receiving TRM compared to controls without TRM transfer. We hypothesized that the enhanced kinetics of OVA presentation in DLN mediated by TRM antigen recognition would result in more rapid systemic activation of OVA-specific CD4 T cells. We thus transferred an indicator population of naïve OVA-specific CD4 T cells intravenously to mice receiving TRM transfer or not prior to OVA protein administration. Faster kinetics of naïve T cell activation were seen in recipients of TRM within 3 days as judged by expression of activation markers and proliferation. Most importantly, by day 4, responding naïve cells reached the lung in greater numbers and were more functional in mice receiving TRM. Our results reveal that CD4+ TRM activation can enhance the kinetics of antigen presentation in DLNs and suggest this mechanism can be harnessed by vaccines to fully integrate protective local and systemic CD4 T cell responses. Supported by grants from NIH (R21 R21AI148882)

Oncolytic Vaccinia Virus Augments T Cell Factor 1-Positive Stem-like CD8+ T Cells, Which Underlies the Efficacy of Anti-PD-1 Combination Immunotherapy.

Oncolytic virotherapy has garnered attention as an antigen-agnostic therapeutic cancer vaccine that induces cancer-specific T cell responses without additional antigen loading. As anticancer immune responses are compromised by a lack of antigenicity and chronic immunosuppressive microenvironments, an effective immuno-oncology modality that converts cold tumors into hot tumors is crucial. To evaluate the immune-activating characteristics of oncolytic vaccinia virus (VACV; JX-594, pexastimogene devacirepvec), diverse murine syngeneic cancer models with different tissue types and immune microenvironments were used. Intratumorally administered mJX-594, a murine variant of JX-594, potently increased CD8+ T cells, including antigen-specific cancer CD8+ T cells, and decreased immunosuppressive cells irrespective of tissue type or therapeutic efficacy. Remodeling of tumors into inflamed ones by mJX-594 led to a response to combined anti-PD-1 treatment, but not to mJX-594 or anti-PD-1 monotherapy. mJX-594 treatment increased T cell factor 1-positive stem-like T cells among cancer-specific CD8+ T cells, and anti-PD-1 combination treatment further increased proliferation of these cells, which was important for therapeutic efficacy. The presence of functional cancer-specific CD8+ T cells in the spleen and bone marrow for an extended period, which proliferated upon encountering cancer antigen-loaded splenic dendritic cells, further indicated that long-term durable anticancer immunity was elicited by oncolytic VACV.

JAK1 signaling in dendritic cells promotes peripheral tolerance in autoimmunity through PD-L1-mediated regulatory Tcell induction.

Dendritic cells (DCs) induce peripheral Tcell tolerance, but cell-intrinsic signaling cascades governing their stable tolerogenesis remain poorly defined. Janus Kinase 1 (JAK1) transduces cytokine-receptor signaling, and JAK inhibitors (Jakinibs), including JAK1-specific filgotinib, break inflammatory cycles in autoimmunity. Here, we report in heterogeneous DC populations of multiple secondary lymphoid organs that JAK1 promotes peripheral Tcell tolerance during experimental autoimmune encephalomyelitis (EAE). Mice harboring DC-specific JAK1 deletion exhibit elevated peripheral CD4+ Tcell expansion, less regulatory Tcells (Tregs), and worse EAE outcomes, whereas adoptive DC transfer ameliorates EAE pathogenesis by inducing peripheral Tregs, programmed cell death ligand 1 (PD-L1) dependently. This tolerogenic program is substantially reduced upon the transfer of JAK1-deficient DCs. DC-intrinsic IFN-γ-JAK1-STAT1 signaling induces PD-L1, which is required for DCs to convert CD4+ Tcells into Tregs invitro and attenuated upon JAK1 deficiency and filgotinib treatment. Thus, DC-intrinsic JAK1 promotes peripheral tolerance, suggesting potential unwarranted DC-mediated effects of Jakinibs in autoimmune diseases.

Combined effects of oncolytic vaccinia virus and dendritic cells on the progression of melanoma B16-F10 in mice

Aim: We aimed to test the hypothesis that loading of dendritic cells (DCs) with both viral and tumor-specific antigens would enhance the efficacy antitumor DC-based therapy applied simultaneously with oncolytic virus. Methods: Vaccinia virus LIVP/GFP and melanoma B16-F10 were used in this study. DCs were pulsed with various combinations of viral and tumor-associated antigens. The maturation status of DCs was verified by expression of the markers CD80, CD86, and CCR7 and assessment of IL-6, TNF-α, and IL-12 secretion. The most efficient combination of antigens for DC loading was selected based on the analysis of the cytotoxic activity of T lymphocytes. Combination therapy using vaccinia virus LIVP/GFP and DCs pulsed with viral and tumor-specific antigens was administered to the B16-F10 melanoma/mouse C57Bl tumor model. Results: We found that loading of DCs with viral antigens, or with a combination of viral and tumor antigens, resulted in similar levels of expression of DC maturation markers. The maximal in vitro cytotoxicity against virus-infected and non-infected B16 melanoma cells exhibited T lymphocytes activated by DCs loaded with the heat inactivated lysate of vaccinia virus LIVP/GFP infected tumor cell. The results show that the combination of vaccinia virus LIVP/GFP and DCs loaded with both tumor and viral antigens inhibit tumor growth of B16-F10 murine melanoma by more than two-fold. Conclusions: Combination therapy with oncolytic vaccinia virus LIVP/GFP and tumor/virus antigen-loaded DCs limited the growth of established melanoma B16-F10, but no synergistic antitumor effects were observed. We propose that optimization of the therapy regimen could enhance the efficiency of combination therapy.

Vaccines Against Different Types of Cancer: Literature Review

According to the World Health Organization, in 2018, cancer was considered the second leading cause of death in the world, corresponding to 9.6 million deaths. Faced with this situation, some alternatives to combat tumors in some organs were developed, such as immunotherapy involving vaccines. Among the vaccines already developed, Sipuleucel-T (Provenge®) can be mentioned, that has been approved by the Food and Drug Administration in 2010 for cases of metastatic prostate cancer; prophylactic bivalent and quadrivalent vaccines to human papillomavirus; the nanoparticulate liposomal RNA vaccine, the melanoma FixVac (BNT111); peptide-based vaccines, such as carcinoembryonic antigen, and those that involve antigen-loaded dendritic cells for the treatment of colorectal cancer, as well as colorectal cancer stem cell-based vaccines and, for cases of ovarian cancer, dendritic cell vaccines. In relation to breast cancer, research is aimed at both immunotherapy with dendritic cells pulsed with tumor antigens and vaccines that have a combined therapy of dendritic cells and Natural Killer cells. In general, vaccines promote the induction of helper and cytotoxic cells to thereby eliminate tumor cells. This characteristic of using dendritic cells with tumor antigens already processed and presented on the cell surface allows the questioning about the use of the term “vaccine”, since it does not correspond to conventional vaccines. Thus, the studies carried out in this area of immunotherapy, although complex and expensive, show promise in the treatment of several types of cancer, with great possibilities of positively impacting the lives of all those who suffer from the disease.

Phase 1 trial of autologous dendritic cell vaccination with imiquimod immunomodulation in children and adults with refractory sarcoma.

11542 Background: Sarcomas are rare, heterogeneous, and aggressive neoplasms that often affect otherwise healthy individuals. Patients with advanced or metastatic sarcomas have dismal outcomes. Immunotherapy presents promising new modalities to help treat sarcomas. One such therapy, autologous dendritic cell (DC) vaccines, using antigen-loaded DCs, intensify the adaptive immune response by enhancing T-cell activity and inducing tumor cell death through apoptosis and cytolysis. We present the results of a phase 1 study of DC vaccine for refractory sarcomas. Methods: A phase 1 dose-escalation study of autologous DC vaccination was conducted in children and adults with recurrent/refractory sarcomas who underwent surgical resection of a primary or metastatic tumor between 2014-2019. A 5+3 dose-escalation schema was chosen to determine safety and recommended phase 2 dose. Patient monocytes were collected by pheresis and incubated with GM-CSF plus IL-4 to generate immature DCs which were then loaded with autologous tumor lysates from the patient’s surgical resection. Three dose levels, 3, 6, and 12 million DCs per treatment were tested. The DC product was administered intradermally in imiquimod-treated skin to complete in situ maturation. Treatment consisted of four weekly injections of the DC product, followed by four monthly “boosters” of tumor lysate. The primary and secondary endpoints included safety/feasibility and preliminary clinical efficacy, respectively. Results: Nineteen patients were enrolled with a median age 50 years (13-75 years) and 47% female. Seven patients were treated on dose level 1 and six each on dose level 2 and 3. Thirteen patients received all planned injections while the remaining six patients progressed during treatment. There was no treatment related dose limiting toxicity. Grade 1-2 fever, headache, arthralgia, injection site reaction attributable to treatment were noted in four patients. There were no adverse events > grade 2. Disease progression before or after completion of study treatment was noted in 15 patients with a median PFS of 9.5 months (95%CI 5.6-28.7). The two-year PFS and OS was 36.8% and 68.1%, respectively. There were seven deaths due to disease, one patient was discharged to hospice and two patients have been lost to follow up. Five patients are currently receiving alternative therapy. Four patients remain in follow up without evidence of disease progression including three patients (pleomorphic myxofibrosarcoma, pleomorphic myosarcoma, and leiomyosarcoma) who are disease free over two years from initiating study therapy and one pediatric patient (Ewing sarcoma) disease free for over one year. Conclusions: Autologous DC vaccine with imiquimod immunomodulation for patients with relapsed/refractory sarcomas is feasible and well-tolerated. Refinement to augment initial and sustained antitumor activity is needed. Clinical trial information: NCT01803152.

COMPARATIVE ANALYSIS OF IMPACT OF TUMOUR ANTIGEN PREPARATION METHODS ON HUMAN DENDRITIC CELLS PRIMING AND EFFICIENT CYTOKINE-INDUCED KILLER CELLS ACTIVATION IN VITRO

Adaptive cell immunotherapy namely combination of dendritic cells (DC) and cytokine-induced killer (CIK) cells is a promising tool in treating various types of cancer and choosing the appropriate technique of tumour antigens obtaining is a challenging issue. CIK cells also called NKT cells are an in vitro propagated population of cells characterized by hybrid NK cells and T cells phenotype. DCs are highly specialized antigen-presenting cells, which uptake, process and present antigens to effector cells of the immune system. In this study, we compared the effect of tumour antigens obtained by different methods on dendritic cells maturation and their ability to activate CIK cells. Cytotoxicity of CIK cells, generated in two different conditions (whole blood or peripheral blood mononuclear cells), was accessed using SW620 cells as a target by MTT assay. According to obtained results, CIK cells expanded from whole blood showed significantly strong anti-tumoral activity compared to CIK cells generated from peripheral blood mononuclear cells isolated by Histopaque-1077 density gradient centrifugation. Also, we determined that all examined methods of antigen preparation can be used, but only in the case of antigen-loaded DCs cocultivation with CIK cells. Key words: Сytokine-induced killer cell, dendritic cell, immunogenic cell death, damage-associated molecular pattern, TNF-alpha.

Methotrexate enhances antigen presentation and maturation of tumour antigen-loaded dendritic cells through NLRP3 inflammasome activation: a strategy for dendritic cell-based cancer vaccine.

Background:Dendritic cells (DCs) are antigen-presenting cells that play a pivotal role in adaptive cell-mediated immunity by priming and activating T cells against specific tumour and pathogenic antigens. Methotrexate (MTX), a folate derivative, functions as an immunoregulatory agent. However, the possible effect of MTX on tumour antigen-loaded DCs has not yet been investigated.Methods:We analysed the effect of MTX on the maturation and function of DCs along with tumour cell lysates (TCLs). Using bone marrow-derived DCs, we investigated the effect of MTX combined TCL-loaded DCs on T cells priming and proliferation. We also tested the anti-tumour immune effect on DCs when treated with MTX and/or TCL in vivo.Results:MTX combined with TCL not only enhanced DC maturation and stimulated cytokine release but also promoted CD8+ T cell activation and proliferation. The latter was associated with increased tumour antigen uptake and cross-presentation to T cells. Mechanistically, DC maturation and antigen presentation were partly modulated by NLRP3 inflammasome activation. Furthermore, immunisation of mice with MTX and TCL-pulsed DCs before a tumour challenge significantly delayed tumour onset and retarded its growth. This protective effect was due to priming of IFN-γ releasing CD8+ T cells and enhanced killing of tumour cells by cytotoxic T lymphocytes isolated from these immunised mice.Conclusion:MTX can function as a potent adjuvant in DC vaccines by increasing antigen presentation and T cell priming. Our findings provide a new strategy for the application of DC-based anti-tumour immunotherapy.

Th17-inducing autologous dendritic cell vaccination promotes antigen-specific cellular and humoral immunity in ovarian cancer patients

In ovarian cancer (OC), IL-17-producing T cells (Th17s) predict improved survival, whereas regulatory T cells predict poorer survival. We previously developed a vaccine whereby patient-derived dendritic cells (DCs) are programmed to induce Th17 responses to the OC antigen folate receptor alpha (FRα). Here we report the results of a single-arm open-label phase I clinical trial designed to determine vaccine safety and tolerability (primary outcomes) and recurrence-free survival (secondary outcome). Immunogenicity is also evaluated. Recruitment is complete with a total of 19 Stage IIIC-IV OC patients in first remission after conventional therapy. DCs are generated using our Th17-inducing protocol and are pulsed with HLA class II epitopes from FRα. Mature antigen-loaded DCs are injected intradermally. All patients have completed study-related interventions. No grade 3 or higher adverse events are seen. Vaccination results in the development of Th1, Th17, and antibody responses to FRα in the majority of patients. Th1 and antibody responses are associated with prolonged recurrence-free survival. Antibody-dependent cell-mediated cytotoxic activity against FRα is also associated with prolonged RFS. Of 18 patients evaluable for efficacy, 39% (7/18) remain recurrence-free at the time of data censoring, with a median follow-up of 49.2 months. Thus, vaccination with Th17-inducing FRα-loaded DCs is safe, induces antigen-specific immunity, and is associated with prolonged remission.

Closing the system: production of viral antigen-presenting dendritic cells eliciting specific CD8+ T cell activation in fluorinated ethylene propylene cell culture bags

BackgroundA major obstacle to anti-viral and -tumor cell vaccination and T cell immunotherapy is the ability to produce dendritic cells (DCs) in a suitable clinical setting. It is imperative to develop closed cell culture systems to accelerate the translation of promising DC-based cell therapy products to the clinic. The objective of this study was to investigate whether viral antigen-loaded monocyte-derived DCs (Mo-DCs) capable of eliciting specific T cell activation can be manufactured in fluorinated ethylene propylene (FEP) bags.MethodsMo-DCs were generated through a protocol applying cytokine cocktails combined with lipopolysaccharide or with a CMV viral peptide antigen in conventional tissue culture polystyrene (TCPS) or FEP culture vessels. Research-scale (< 10 mL) FEP bags were implemented to increase R&D throughput. DC surface marker profiles, cytokine production, and ability to activate antigen-specific cytotoxic T cells were characterized.ResultsMonocyte differentiation into Mo-DCs led to the loss of CD14 expression with concomitant upregulation of CD80, CD83 and CD86. Significantly increased levels of IL-10 and IL-12 were observed after maturation on day 9. Antigen-pulsed Mo-DCs activated antigen-responsive CD8+ cytotoxic T cells. No significant differences in surface marker expression or tetramer-specific T cell activating potency of Mo-DCs were observed between TCPS and FEP culture vessels.ConclusionsOur findings demonstrate that viral antigen-loaded Mo-DCs produced in downscaled FEP bags can elicit specific T cell responses. In view of the dire clinical need for closed system DC manufacturing, FEP bags represent an attractive option to accelerate the translation of promising emerging DC-based immunotherapies.

Dendritic Cells Transfected with MHC Antigenic Determinants of CBA Mice Induce Antigen-Specific Tolerance in C57Bl/6 Mice.

Background Nonspecific immunosuppressive therapy for graft rejection and graft-versus-host disease (GVHD) is often accompanied by severe side effects such as opportunistic infections and cancers. Several approaches have been developed to suppress transplantation reactions using tolerogenic cells, including induction of FoxP3+ Tregs with antigen-loaded dendritic cells (DCs) and induction of CD4+IL-10+ cells with interleukin IL-10-producing DCs. Here, we assessed the effectiveness of both approaches in the suppression of graft rejection and GVHD. Methods IL-10-producing DCs were generated by the transfection of DCs with DNA constructs encoding mouse IL-10. Antigen-loaded DCs from C57BL/6 mice were generated by transfection with DNA constructs encoding antigenic determinants from the H2 locus of CBA mice which differ from the homologous antigenic determinants of C57BL/6 mice. Results We found that both IL-10-producing DCs and antigen-loaded immature DCs could suppress graft rejection and GVHD but through distinct nonspecific and antigen-specific mechanisms, respectively. Discussion. We provide data that the novel approach for DCs antigen loading using DNA constructs encoding distinct homologous determinants derived from major histocompatibility complex genes is effective in antigen-specific suppression of transplantation reactions. Such an approach eliminates the necessity of donor material use and may be useful in immunosuppressive therapy side effects prevention.

Generation of dendritic cells using viral lysate of tumor cells in vitro.

e15202 Background: The purpose of the study was to investigate the effect of a new unclassified rotavirus on the effectiveness of maturation of dendritic cells (DC) and their activation of lymphocytes in vitro. Methods: Strain No.100 of the RVK virus was isolated by S.A. Kolpakov and characterized as rotavirus. U87MG cell lysate (glioblastoma) was obtained by incubation with 108 RVK particles in the DMEM medium with L-glutamine for 72 hours; a cytopathic effect was observed. Immature DCs were cultured for 7 days in the presence of IL-4 and GM-CSF. For antigen loading of DCs, we used the following options for 48 h: a) U87MG lysate obtained by repeated freeze-thaw cycles (TL); b) U87MG lysate obtained by co-cultivation with RVK (VTL); c) RVK. To assess the DC ability to activate autologous lymphocytes, they were co-cultured for 5 days in a 3:1 ratio. Results: The use of VTL culture for DC loading caused an increase in the expression of mature DC (mDC) markers compared to TL: the number of CD83+/CD86+ cells increased by more than 2 times, CD83+/CD80+ by 1.2 times, CD83+HLA-DR - by 5.5 times. With VTL, expression of markers of immature DCs (CD1a, CD14) was minimal. The use of RVK as an antigen induced the generation of DCs from monocytes, but their maturation was much less pronounced: a significant increase in the membrane expression of CD86, but not CD83, was determined. These DCs demonstrated a higher expression of markers of immature DCs, compared to stimulation with cell lysates (both TL and VTL): CD1a and CD14; CD80+/CD86+ level was the highest among all options. Analysis of the DC effect on co-cultivated lymphocytes showed that DCs loaded with RVK, both alone and as part of VTL, stimulated predominantly the NKT subpopulation. The same samples contained more T lymphocytes, activated CD4+ and CD8+ compared to samples stimulated by TL. However, the samples co-cultivated with VTL contained the maximal amount of CD4+/CD25+/CD127dim phenotypically corresponding to Tregs. Conclusions: The antigen loading of immature DCs with RVK alone causes their activation, but not maturation, which is not realized in typical terms of the DC generation from blood monocytes. The presence of RVK, including in VTL, has a stimulating effect on NKT lymphocytes suggesting the possible generation of specific highly active cytotoxic lymphocytes.