Pulsed Dendritic Cells Research Articles

DEX Immunotherapy Pharmaco-Biotechnological Advances in Multimodal Therapy for Cancer

This article reviews the synergy between pulsed dendritic cell exosome (DEX) immunotherapy and chemotherapy in cancer treatment. DEX exosomes, which act as immune system modulators, enhance chemotherapy efficacy by modifying the tumor microenvironment and activating an immune response targeted against tumor cells. This combination not only amplifies cancer cell destruction but also protects healthy cells, thus reducing systemic adverse effects of chemotherapy. The article highlights preclinical and clinical advances demonstrating the effectiveness of this combined strategy, showing promising results in tumors resistant to conventional treatments. Despite the benefits, challenges such as the high production cost of exosomes and the need to optimize treatment protocols for different cancer types are identified. Additionally, future research directions are presented, focusing on improving personalized treatments through genetically modified exosomes. In conclusion, the combination of DEX and chemotherapy has the potential to revolutionize cancer treatment, enhancing both treatment tolerance and clinical efficacy.

A pilot trial of personalized neoantigen pulsed autologous dendritic cell vaccine as adjuvant treatment in hepatocellular carcinoma.

e16264 Background: The primary treatment for hepatocellular carcinoma (HCC) is radical surgery. However, HCC has a high propensity to recur postoperatively and no standard adjuvant therapies have been approved. This Phase I trial aims to evaluate the safety and efficacy of an adjuvant personalized neoantigen pulsed autologous dendritic cell vaccine (Neo-DCVac-02) in patients with HCC. Methods: Eligible patients had histologically confirmed high-risk HCC after radical surgery. After obtaining the necessary baseline biopsy specimens and PBMCs of appropriate quality for DNA and RNA sequencing, neoantigen prediction, screening and synthesis were performed. Subsequently, leukapheresis was performed and DCs were isolated and cultured. DCs were then pulsed with neoantigen peptides to produce Neo-DCVac-02. On day 0, patients were treated with cyclophosphamide at a dose of 250 mg/m2. The prepared Neo-DCVac-02 vaccine was administered subcutaneously to the axillary and inguinal regions bilaterally on day 1, followed by daily administration of GM-CSF at a dose of 0.075 mg for 5 days (days 2-6). The primary objectives of this study were to assess feasibility and safety/tolerability. Secondary objectives included evaluation of immune responses (via vaccine response: IFNγ ELISpot), relapse-free survival (RFS) and overall survival (OS). Results: A total of 32 patients provided informed consent to initiate the process of personalized neoantigen discovery, of which 26 (81%) met the requirements for successful product selection for clinical manufacturing. Feasibility was demonstrated with 13 patients receiving Neo-DCVac-02. 13 patients did not receive the neoantigen vaccine (7 due to progressive disease, 6 due to withdrawal of informed consent because of COVID-19). The treatment was well tolerated with no grade 2+ treatment-related adverse events (TRAEs). The most common Grade 1 TRAEs were injection site reactions (75%), rash (16.7%), fatigue (8.3%), neutropenia (8.3%), and headache (8.3%). Five of 13 evaluable patients showed increased antigen-specific T-cell activity and more than 50% of the neoantigen peptides in Neo-DCVac-02, and sustained cellular responses were observed up to one year. Increases in T-cell activation/co-stimulation seen after treatment with Neo-DCVac-02, as demonstrated by flow cytometric analysis, suggest immune priming. At a median follow-up of 29.7 months, median RFS was not reached, with 1- and 2-year RFS of 84.6% and 60%, respectively, and all patients are alive. Patients with a strong immune response had a longer median relapse-free survival (not reached) compared to patients with a weak immune response (17.6 months, P = 0.003). Conclusions: These data demonstrate that Neo-DCVac-02 is safe, well tolerated and capable of inducing durable antigen-specific lymphocyte immune responses that may correlate with delayed HCC recurrence. Clinical trial information: NCT04147078 .

Immunomodulatory effects of Diospyros peregrina fruit preparation (DFP) in non-small cell lung cancer (NSCLC) by utilizing dendritic cell-mediated antigen presentation and T helper (TH) cell differentiation.

Diospyros peregrina is a dioecious plant which is native to India. It belongs to the family of Ebenaceae and is extensively used to treat various ailments, such as leucorrhoea and other uterine-related problems. Though few studies have been on D. peregrina for their anti-tumour response, little is known. Therefore, this intrigued us to understand its immunomodulator capabilities on various types of cancer extensively. Our primary focus is on NSCLC (Non-Small Cell Lung Cancer), which is ranked as the second largest form of cancer in the world, and the treatments demand non-invasive agents to target NSCLC effectively. In an objective to generate an efficient Lung Cancer Associated Antigen (LCA) specific anti-tumour immune response, LCA was presented using dendritic cells (DCs) in the presence of D. peregrina fruit preparation (DFP). Moreover, we also investigated DFP's role in the differentiation of T-helper (TH) cells. Therefore, this study aimed at better LCA presentation mediated by DFP by activating the LCA pulsed DCs and T helper cell differentiation for better immune response. DCs were pulsed with LCA for tumour antigen presentation in vitro, with and without DFP. Differentially pulsed DCs were irradiated to co-culture with autologous and allogeneic lymphocytes. Extracellular supernatants were collected for the estimation of cytokine levels by ELISA. LDH release assay was performed to test Cytotoxic T lymphocytes (CTLs) mediated lung tumour cell cytotoxicity. Thus, DFP may be a potential vaccine to generate anti-LCA immune responses to restrict NSCLC.

Development of dendritic cell loaded MAGE-A2 long peptide; a potential target for tumor-specific T cell-mediated prostate cancer immunotherapy

BackgroundProstate cancer (PCa) is the second leading cause of cancer-related deaths among men worldwide. Immunotherapy is an emerging treatment modality for cancers that harnesses the immune system’s ability to eliminate tumor cells. In particular, dendritic cell (DC) vaccines, have demonstrated promise in eliciting a tumor-specific immune response. In this study, we investigated the potential of using DCs loaded with the MAGE-A2 long peptide to activate T cell cytotoxicity toward PCa cell lines.MethodsHere, we generated DCs from monocytes and thoroughly characterized their phenotypic and functional properties. Then, DCs were pulsed with MAGE-A2 long peptide (LP) as an antigen source, and monitored for their transition from immature to mature DCs by assessing the expression levels of several costimulatory and maturation molecules like CD14, HLA-DR, CD40, CD11c, CD80, CD83, CD86, and CCR7. Furthermore, the ability of MAGE-A2 -LP pulsed DCs to stimulate T cell proliferation in a mixed lymphocyte reaction (MLR) setting and induction of cytotoxic T cells (CTLs) in coculture with autologous T cells were examined. Finally, CTLs were evaluated for their capacity to produce interferon-gamma (IFN-γ) and kill PCa cell lines (PC3 and LNCaP).ResultsThe results demonstrated that the antigen-pulsed DCs exhibited a strong ability to stimulate the expansion of T cells. Moreover, the induced CTLs displayed substantial cytotoxicity against the target cells and exhibited increased IFN-γ production during activation compared to the controls.ConclusionsOverall, this innovative approach proved efficacious in targeting PCa cell lines, showcasing its potential as a foundation for the development and improved PCa cancer immunotherapy.

CTIM-15. T CELL RESPONSE DYNAMICS IN PHASE 3 GLIOBLASTOMA PATIENTS IMMUNIZED WITH AUTOLOGOUS DENDRITIC CELLS PULSED WITH AUTOLOGOUS TUMOR CELL LYSATE

Abstract BACKGROUND 331 glioblastoma patients were immunized with autologous dendritic cells (DCs) pulsed with autologous tumor cell lysate or placebo in a Phase 3 clinical trial. Immunization with the pulsed DCs was associated with extended overall survival in both newly diagnosed and recurrent disease. Objective: To characterize T cell responses and T cell response dynamics in patients immunized with autologous dendritic cells pulsed with autologous tumor cell lysate. METHODS we performed T cell receptor sequencing on peripheral blood mononuclear cells from both newly diagnosed and recurrent glioblastoma patients that were treated with the pulsed DCs. Timepoints from both before and after immunization were compared to understand T cell response dynamics. RESULTS Expansion of several hundred new T cell clones as well as more than 700 previously detected T cell clones was detected over time in both newly diagnosed and recurrent GBM patients who were treated with the pulsed DCs. Investigation of the dynamics of the response demonstrated that further expansion was triggered by ongoing immunizations. Correlations between T cell response data and clinical outcomes are ongoing. CONCLUSION Immunization with autologous DCs pulsed with autologous tumor cell lysate induces broad spectrum immune responses in patients with glioblastoma.

Immunological analysis of hybrid neoantigen peptide encompassing class I/II neoepitope-pulsed dendritic cell vaccine.

Neoantigens/ are tumor-specific antigens that evade central immune tolerance mechanisms in the thymus. Long-term tumor-specific cytotoxic T lymphocyte activity maintenance requires class II antigen-reactive CD4+ T cells. We had previously shown that intranodal vaccination with class I neoantigen peptide-pulsed dendritic cells (DCs) induced a robust immune response in a subset of patients with metastatic cancer. The present study aimed to perform a detailed ex vivo analysis of immune responses in four patients receiving an intranodal hybrid human leukocyte antigen class II neoantigen peptide encompassing a class I neoantigen epitope (hybrid neoantigen)-pulsed DC vaccine. After vaccination, strong T-cell reactions against the hybrid class II peptide and the class I-binding neoantigen peptide were observed in all four patients. We found that hybrid class II neoantigen peptide-pulsed DCs stimulated CD4+ T cells via direct antigen presentation and CD8+ T cells via cross-presentation. Further, we demonstrated that hybrid class II peptides encompassing multiple class I neoantigen epitope-pulsed DCs could present multiple class I peptides to CD8+ T cells via cross-presentation. Our findings provide insight into the mechanisms underlying hybrid neoantigen-pulsed DC vaccine therapy and suggest future neoantigen vaccine design.

Cell Communication‐Mediated Selective Drug Delivery for Epitope‐Specific Deletion of Alloreactive T Cells in Organ Transplant

AbstractAllogeneic grafts are vulnerable to the attack launched by host alloreactive T cells, which accounts primarily for allograft failure in the clinic. Conventional pharmacological intervention mainly involves broad‐acting, nonspecific immunosuppressants that provide limited protection over the graft and may cause deleterious side effects due to insufficient allospecificity. Here, core–shell structured nanoparticles co‐loaded with allogeneic antigen (Ag) and immunosuppressive agent Tacrolimus (Ag@FK506‐NPs) are constructed. Dendritic cells (DCs) pulsed with Ag@FK506‐NPs present alloantigenic epitopes on the cell surface as a bait to capture specific T cells, especially CD8+ T cells, for intercellular FK506 transfer and alloreactive T‐cell deletion. Meanwhile, DCs are maintained in an immature tolerogenic state that induces the functional inactivation of recruited T cells. Compared with free FK506, the adoptive transfer of low immunosuppressant dose (25 000‐fold lower) of Ag@FK506‐NPs pulsed DCs is enough to yield a superior antirejection effect in a major histocompatibility complex‐mismatched murine skin transplant model. Of note, due to the cell–cell communication conferred selective T‐cell suppression, the recipient mouse is able to respond to the subsequent stimulation of an irrelevant Ag, indicating that off‐target toxicity is bypassed. Overall, this work may address some of the limitations of current allograft therapeutics.

A pilot trial of personalized neoantigen pulsed autologous dendritic cell vaccine as adjuvant treatment in hepatocellular carcinoma.

e14658 Background: The primary means of treating hepatocellular carcinoma (HCC) is radical surgery. However, HCC has a high propensity to recur post-operatively, and no standard adjuvant therapies have been approved. Tumor neoantigens, which are epitopes derived from tumor-specific mutations, may be utilized in personalized vaccines to activate T cell responses. This trial aims to assess the safety and efficacy of personalized neoantigen pulsed autologous dendritic cell vaccine (Neo-DCVac-02) in patients with HCC. Methods: Eligible patients had histologically confirmed high-risk HCC after radical surgery. Upon obtaining the baseline biopsy specimens and PBMCs of appropriate quality for DNA and RNA sequencing, neoantigen prediction, screening, and synthesis were performed. Subsequently, autologous dendritic cells (DCs) were generated and pulsed with neoantigen peptides to produce Neo-DCVac-02.On day 0, patients were treated with cyclophosphamide at a dose of 250 mg/m2. The prepared Neo-DCVac-02 vaccine was administered subcutaneously on day 1, followed by GM-CSF administered daily for 5 days. The primary objectives of this study were to evaluate the feasibility and safety/tolerability. Secondary objectives included assessment of immune responses (via vaccine response: IFNγ ELISpot), recurrence-free survival (RFS), and overall survival (OS). Results: A total of 32 patients provided informed consent to initiate the process of personalized neoantigen discovery, of which 26 (81%) met the requirements for successful product selection for clinical manufacturing. And feasibility was shown with 13 patients receiving Neo-DCVac-02. Thirteen patients did not receive neoantigen vaccines (7 for progressive disease,6 for withdrawal of informed consent because of COVID-19). Treatment was well-tolerated with no grade 2+ treatment-related adverse events (TRAEs). The common grade 1TRAEs were neutropenia (8.3%), injection site reactions (75%), rash (16.7%), fatigue (8.3%), and headache (8.3%). The median follow-up to date is 19.30 (14.4-31.9) months, with median RFS and OS not yet reached and a 1-year RFS of 83%. Five of 13 evaluable patients showed elevated antigen-specific T-cell activity by IFNγ ELISpot for more than 50% of neoantigen peptides in Neo-DCVac-02, and persistent cellular responses were noted out to 1 year. Increases in activation/co-stimulatory of T cells seen after treatment with Neo-DCVac-02 revealed by Flow-cytometric analyses, suggest immune priming. Conclusions: These data demonstrate that Neo-DCVac-02 is safe, well tolerated, and able to generate durable antigen-specific lymphocyte immune responses. Early signs of clinical efficacy were observed in HCC patients. Clinical trial information: NCT04147078 .

Engineering an active immunotherapy for personalized cancer treatment and prevention of recurrence.

Breast cancer has been shown to be resistant to immunotherapies. To overcome this challenge, we developed an active immunotherapy for personalized treatment based on a smart nanovesicle. This is achieved by anchoring membrane-bound bioactive interleukin 2 (IL2) and enriching T cell-promoting costimulatory factors on the surface of the dendritic cell-derived small extracellular vesicles. This nanovesicle also displays major histocompatibility complex-bound antigens inherited from tumor lysate-pulsed dendritic cell. When administrated, the surface-bound IL2 is able to guide the nanovesicle to lymphoid organs and activate the IL2 receptor on lymphocytes. Furthermore, it is able to perform antigen presentation in the replacement of professional antigen-presenting cells. This nanovesicle, named IL2-ep13nsEV, induced a strong immune reaction to rescue 50% of the mice in our humanized patient-derived xenografts, sensitized cancer cells to immune checkpoint inhibitor treatment, and prevented the recurrence of resected tumors. This paradigm presents a feasible strategy for the treatment and prevention of metastatic breast cancer.

Abstract 3200: Non-engineered T cells with specific anticancer effects in KRAS-mutated colorectal cancer

Abstract Cytokine-induced killer (CIK) cell therapy is known as a useful treatment for cancer immunotherapy due to its anticancer activity and safety. However, its clinical efficacy is limited due to its lack of antigen specificity and low in vivo persistence. KRAS mutations play an important role in promoting tumorigenesis in cancer. But, its clinical application as a biomarker for cancer treatment is still difficult. Non-engineered T cell therapy approaches could be a promising strategy for treating KRAS-mutated cancer. Herein we developed non-engineered T cells empowered with specific anticancer effects in KRAS-mutated colorectal cancer (CRC), and investigated its properties and anticancer effects compared to CIK cells. A recombinant overlapping peptide was designed to overlap the KRAS protein by 15 amino acids linked by a cathepsin S cleavage site (LRMK). It contained KRASG12D, KRASG12V, KRASG13D, and KRASWT epitope peptides and other KRAS protein regions. Peripheral blood mononuclear cells (PBMCs) from CRC patients with KRAS mutations were stimulated with the recombinant overlapping peptides in vitro for two days in the presence of interleukin (IL)-4, granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor (TNF)-α, IL-1β, and prostaglandin 2, and expanded using the 12-day CIK cell expansion method in the presence of IL-2 (200 IU/mL). To verify the enrichment of KRAS mutant-specific T cells, the expanded T cells were restimulated by pulsed monocyte-derived dendritic cells with KRAS mutant antigen for two days and the frequency of KRAS mutation-specific T cells was determined using the interferon (INF)-γ capture assay. Red fluorescent protein (RFP)-expressing HLA-matched cell lines and cell line-derived spheroids T3M10 (KRASG12D) and MCF-7 (KRASWT) were used for the Incucyte immune cell killing assay. T-cell phenotypes were determined by flow cytometry. The expanded non-engineered T cells stimulated with KRAS mutant antigen showed skewed CD4 T cell differentiation and increased central memory T cells compared to CIK cells, suggesting that they may have more long-term immunity and functionality than CIK cells. The KRASG12D-specific T cells were enriched 12-13% (9.4-fold) by in vitro stimulation compared to 1.3% in CIK cells. Anticancer activity in a 2D-culture model was significantly higher in KRASG12D-specific enriched T cells (82.5%) than in CIK cells (64.9%) co-cultured with T3M10 cells for 48 h. In a 3D spheroid-culture model, increased cytotoxicity was also detectable in the KRASG12D-specific enriched T cells (13.2% at 72 h and 14.1% at 142 h) compared to CIK cells. These results demonstrated that non-engineered T cells with KRAS mutated-specific anticancer activity are an ideal candidate for KRAS mutant cancer-targeted immunotherapy. Further studies are necessary to verify the anticancer effects in vivo. Citation Format: Sunki Lim, Yujeong Gho, Seoyoung Kim, Min Ki Kim, Jong Seob Park, Wang Jun Lee, Young-Kwan Lee, Hyoun Jong Moon, Excelsisbio.Inc, Goyang, Korea. Non-engineered T cells with specific anticancer effects in KRAS-mutated colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3200.

Abstract 696: Sensitizing breast cancers to immune checkpoint inhibitors through CD27 agonism and vaccination against tumor-associated antigen

Abstract Project objective: Despite the recent revolution in immune checkpoint inhibitors (ICIs), only modest improvement in overall survival and likely caused by not enough potent cellular immunity among BC patients. Our lab has been focus on inducing cellular immunity against HER2+ BC through vaccination against the tumor-associated antigen HER2. Approximately 20 years ago, we performed an experimental pilot study by administrating HER2 peptide and recombinant protein pulsed dendritic cells (DC vaccine) to six patients with refractory HER2+ advanced or metastatic (stage II (≥ 6 +LN), III, or stage IV) BC. We followed the patients on 2019 found that all of the six patients were still alive, 18 years after vaccination. Their blood sample were analyzed with cytometry by time-of-flight (CyTOF) and found there is a significantly increased presence of CD27 expressing memory T cells in response to HER2 peptide stimulation. Recent report on the SARS-CoV2 mRNA vaccine also suggested that CD27 expressing memory T cells plays a critical role in long-lasting cellular immunity against SARS-CoV2 infection. Therefore, we hypothesized that CD27 plays a critical role in cellular immunity against BC, and the stimulation of CD27 expressing T cells with mAb targeting CD27 significantly increase the cellular immunity triggered by vaccination against tumor-associated antigen. Results: We recapitulate the rise of CD27+ antigen specific T cells among the vaccinated patients using a transgenic mouse model expressing human CD27. When combined the adenoviral-vector based HER2 (Ad-HER2) vaccination with a single dose of human aCD27 antibody (Varlilumab), we found there is a robust increase in the HER2 specific T cells compared to vaccination alone, especially CD27+CD44+ memory CD4 T cells, even after 120 days post vaccination. Using an ICI-insensitive syngeneic HER2+ BC models, we found 50% of mice in the combination group of aCD27 antibody plus Ad-HER2 showed total tumor regression by the end of study. When combined with anti-PD1 antibody, the combination of AdHER2 and Varlilumab leads to total tumor regression in 90% of tumor bearing mice with syngeneic HER2+ BC, indicating that the vaccination against tumor associated antigen HER2 plus anti-CD27 antibody sensitized ICI-insensitive HER2+ BC toward ICI. Conclusions: Our data demonstrates that the administration of anti-CD27 antibody significantly increase the long term presence of CD27+ antigen specific memory T cells after vaccination against tumor associated antigen HER2. As consequence, combination of anti-CD27 with HER2 sensitized the immune unresponsive breast cancer toward anti-PD1 antibody. Our study suggests that the vaccination against tumor-associated antigen with mAb targeting CD27 leads to the robust cellular immunity, which is required for successful ICIs against breast cancer. Citation Format: Bin-Jin Hwang, Erika Crosby, Timothy Trotter, Li-Chung Tsao, Tao Wang, Xiao Yang, Herbert Kim Lyerly, Zachary Hartman. Sensitizing breast cancers to immune checkpoint inhibitors through CD27 agonism and vaccination against tumor-associated antigen [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 696.

Abstract P6-10-11: Engineered neoantigen-specific T cell receptors to treat metastatic breast cancer

Abstract T cell receptor engineered T cell (TCR T) therapy has emerged as a promising therapeutic modality for solid cancer following recent trials demonstrating the safety and efficacy of TCR T therapies against some types of metastatic solid cancers. However, the broader application of TCR T towards many solid tumors, including metastatic breast cancer (MBC), has been limited by several factors, chiefly among them the current scarcity of tumor selective target antigens. Neoantigens, which are expressed exclusively in cancer cells, are currently underrepresented in TCR T development, being targeted in only about 7% of trials conducted to date, and thus represent a relatively untapped source of potentially safe and effective novel targets. Driver mutations in AKT1, ESR1, PIK3CA, and TP53 are common in patients with MBC, and could serve as ideal neoantigen targets for TCR T therapies. We hypothesized that we could generate MBC driver mutation-specific T cells from which we could isolate and clone neoantigen-specific TCRs to generate TCR T products for MBC. We identified 13 driver missense mutations that are among the most frequent in patients with MBC, which included AKT1 (E17K), ESR1 (K303R, Y537S, D538G), PIK3CA (E542K, E545K, H1047L, H1047R), and TP53 (R175H, R248Q, R248W, R273C, R273H), then designed peptide libraries consisting of 15-mer overlapping peptides that contain these mutations. To determine if these neopeptides could elicit T cell responses, we isolated T cells from 15 healthy donors and 11 MBC patients who expressed at least one of the targeted mutations and performed successive stimulations with neopeptide pulsed dendritic cells, then screened the resulting T cell lines for neoantigen specificity using an IFN-γ ELISpot assay. We observed neopeptide T cell responses in 8/16 lines generated from healthy donors and 7/11 lines generated from MBC patients, which were collectively directed against 11/13 of the targeted driver mutations. To isolate neoantigen-specific TCRs from one of these lines, we performed IFN-γ capture, limiting dilution, and 5’ RACE, and isolated an HLA-B*35 restricted TP53 R248W-specifc TCR. Gene transfer of this TCR conferred edited T cells with potent activity towards the TP53 R248W and not the TP53 WT peptide as assessed by ELISpot (1036 vs 46 SFU/1 × 105 cells, respectively) and chromium release cytoxicity assay targeting peptide pulsed autologous PHA blasts (37.5% vs 0% lysis at E:T 40:1, respectively). To increase the throughput of TCR discovery, we next used a single cell RNA sequencing based TCR discovery approach whereby we stimulated T cells from one of the generated lines with ESR1 WT or neopeptide and identified responsive T cell clones through upregulation of IFN-γ and/or TNF-α. This strategy has so far enabled us to identify and validate two ESR1 mutant-specific TCRs. This includes an HLA-C*01 restricted TCR that confers edited T cells with dual activity towards both ESR1 Y537S and D538G, but not WT peptide as determined by both ELISpot (2094, 3194, and 79 SFU, respectively) and chromium release cytotoxicity (31.3%, 77.8%, and 9.1% lysis, respectively), as well as an HLA-B*40 restricted TCR that confers high ESR1 Y537S specificity (5039 vs 138 SFU in response to ESR1 Y537S vs WT peptide, respectively). In summary, we have demonstrated responses of T cells derived from both healthy donors and MBC patients towards neopeptides derived from common MBC driver mutations. We have so far isolated neoantigen specific TCRs from two of the neoantigen-specific T cells lines, including TCRs specific towards TP53 R248W, ESR1 Y537S, dual ESR1 Y537S+D538G that are restricted to three different HLA alleles, and have successfully used these TCRs to generate TCR T products with high neoantigen activity. These results encourage further efforts to identify TCRs recognizing these MBC driver mutations, with our ultimate aim to translate neoantigen-targeted TCR T therapies to clinical trials of MBC. Citation Format: Paul Shafer, Wingchi K. Leung, Mae L. Woods, Carlos Rodriguez-Plata, Arushana Ali, Saisha Nalawade, Lauren M. Kelley, Jarrett Joubert, Anthony Manliguez, Spyridoula Vasileiou, Suzanne A. Fuqua, Premal Lulla, Cliona Rooney, Ann Leen, Valentina Hoyos. Engineered neoantigen-specific T cell receptors to treat metastatic breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-10-11.

Estimation of Sensitization Status in Renal Transplant Recipients by Assessing Indirect Pathway CD4 + T Cell Response to Donor Cell-pulsed Dendritic Cell.

Generation of donor-specific human leukocyte antigen antibody (DSA) via indirect allorecognition is detrimental to long-term survival of transplant organs. The detection of such immune responses would make it possible to define patients with high risk of sensitization. In this study, we established a novel method for evaluating indirect allorecognition to assess sensitization in kidney transplant recipients. Recipient CD14 + monocytes were mixed with donor peripheral blood mononuclear cells; cultured in the presence of IL-4, GM-CSF, IL-1β, and TNFα; and used as pulsed dendritic cells (DCs). Cell proliferation and cytokine production were evaluated by carboxyfluorescein diacetate succinimidyl ester-based T cell proliferation assay and Enzyme-Linked ImmunoSpot assay, respectively. CD4 + T cell proliferation was strongly observed in following coculture with allogeneic antigen-pulsed DC leading to interferon-γ and IL-21 production. About 1% of CD4 + T cells exhibited Tfh-like phenotype (PD-1 high CXCR5 + ICOS + CD40L + ). Recipient DC pulsed with donor peripheral blood mononuclear cells was cocultured with recipient CD45RA+CD4+ and CD45RA-CD4+ (generally defined as naive and memory in humans, respectively) T cells. Irrespective of preformed or de novo DSA status, CD45RA + CD4 + T cells constantly produced IL-21. In contrast, IL-21-produced CD45RA - CD4 + T cells were significantly higher in preformed DSA-positive patients than those in negative patients (80.8 ± 51.2 versus 14.8 ± 20.4, P < 0.001). In de novo DSA-positive patients, IL-21-produced CD45RA - CD4 + T cells were significantly increased after transplantation compared with before transplantation (9.23 ± 9.08 versus 43.9 ± 29.1, P < 0.001). Assessment of indirect pathway CD4 + T cell response could provide new insights into the underlying mechanism of de novo DSA production, leading to the development of effective strategies against antibody-mediated rejection.

Toll-like Receptor 9 Induced Dendritic Cell Activation Promotes Anti-Myeloperoxidase Autoimmunity and Glomerulonephritis.

ANCA-associated vasculitis (AAV) is intricately linked with infections. Toll-like receptors (TLR) provide a potential link between infection and anti-myeloperoxidase (MPO) autoimmunity. TLR9 ligation has been shown to promote anti-MPO autoimmunity and glomerular vasculitis in murine MPO-AAV. This study investigates dendritic cell TLR9 ligation in murine experimental anti-MPO glomerulonephritis. We analyzed autoimmune responses to MPO following transfer of TLR9 stimulated, MPO pulsed dendritic cells and kidney injury following a sub-nephritogenic dose of sheep anti-mouse glomerular basement membrane globulin. TLR9 ligation enhanced dendritic cell activation upregulating CD40 and CD80 expression, promoting systemic anti-MPO autoimmunity and T cell recall responses and exacerbating kidney injury. CD40 upregulation by TLR9 was critical for the induction of nephritogenic autoimmunity. The presence of DEC205, which transports the TLR9 ligand to TLR9 located in the endosome, also promoted kidney injury. This confirms TLR9 mediated dendritic cell activation as a mechanism of anti-MPO autoimmunity in AAV and further defines the link between infection and the generation of MPO specific autoimmune inflammation.

A Systematic Review of Potential Immunotherapies Targeting PRAME in Retinoid Resistant Oral Potentially Malignant Disorders and Oral Cancer.

Backgound and objective: Early chemoprevention in Oral Potentially Malignant Disorders (OPMDs) and Oral Cancer (OC) has been extensively researched in order to mitigate the malignant transformation and progression of the lesion. Many agents have been attempted, but their cost inefficacy and inadequate outcomes posed a major hindrance in their successful adoption. Retinoid Based Therapy (RBT) though a cheap and effective treatment option, could not achieve much clinical usage because of variable responsiveness in clinical outcomes. Such clinical response variability may be attributed to the repression of retinoid receptors by Preferentially Expressed Antigen of Melanoma (PRAME) protein molecule. Therefore, in order to make RBT successful, targeting PRAME by various immunotherapies is an exciting area of research investigation. This review provides an insight into the various immunotherapeutic strategies targeting PRAME and their usefulness in retinoid-resistant OPMD and OC. Method of data collection: An exhaustive internet-based literature search following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was carried out in PUBMED and Google SCHOLAR database using terms 'Anti-PRAME' OR 'PRAME Immunotherapy' OR 'PRAME Vaccines' AND 'Cancer' AND 'Retinoid resistance'. Only articles in the English language with at least 1 citation, published in a journal with impact factor ≥ 1, having relevance to the context and availability of full text were considered. Results: After an initial search, 342 articles were yielded on the basis of inclusion criteria and, by reading the abstract and availability of full text, a total of 124 articles were selected. Further reading the full texts and considering articles from the references of the selected articles, a total of 65 articles were finally included in the review. Conclusion: Our analysis of the literature suggests that PRAME screening in OC and OPMDs prior to RBT should be done. In PRAME positive cases, approaches like PRAME based immunotherapy in the form of Cancer vaccine therapy [Acellular PRAME vaccine, PRAME pulsed Dendritic Cells (DC)]; Adoptive T Cell therapy/T Cell Receptor-T Cell therapy, Antibody therapy/Chimeric Antigen Receptor-T Cell therapy along with Presented antigen modulation Therapies employing histone deacetylase inhibitors and demethylation agents seem plausible. In the future, a combination therapy employing either PRAME vaccines or antibodies or Adoptive T cell Therapy and ATRA could be used in retinoid resistant OC and OPMDs.

Bioengineered immunomodulatory organelle targeted nanozymes for photodynamic immunometabolic therapy.

Intelligent nanomedicines integrated with stimuli-responsive components enable on-demand customizable treatment options which would improve therapeutic outcome and reduce systemic toxicity. In this work, we explore the synergistic therapeutic potential of photodynamic therapy and immunometabolic modulation to achieve tumour regression and to trigger an adaptive immunity to prevent tumour recurrence. The therapeutic potential of the fabricated Bioengineered Immunomodulatory Organelle targeted Nanozymes (BIONs) was tested on 3D printed mini-brains which could effectively recapitulate the biologically relevant interactions between glioblastoma cells and macrophages. In the presence of glioblastoma organotypic brain slices, activated BIONs upregulated the cell surface expression of CD86, a costimulatory molecule and CD83, maturation marker, on monocyte derived dendritic cells, suggesting its ability to elicit a strong immune response. Furthermore, the antigen pulsed dendritic cells by chemotaxis and transendothelial migration readily relocate into the draining lymph node where they present the antigenic cargo to enable the proliferation of T lymphocytes. The stealth and tunable catalytic activity of BIONs prevent ROS mediated diseases such as acute kidney injury by providing environment dependent protection without compromising on its promising anti-cancer activity.

A randomised phase II clinical trial of low-dose cyclophosphamide and transarterial chemoembolization (TACE) with or without vaccination with dendritic cells (DC) pulsed with HepG2 lysate ex vivo in patients with hepatocellular carcinoma (HCC): The ImmunoTACE trial.

4012 Background: A previous study by our group using autologous monocyte-derived DC pulsed ex vivo with HepG2 cell lysate showed some clinical benefit with evidence of antigen-specific T-cell responses in patients with advanced HCC. The current trial reports the activity of this vaccine in combination with TACE in patients with HCC. All patients also received low-dose cyclophosphamide to deplete regulatory T cells and thereby enhance vaccination. Methods: Patients with intermediate stage HCC (performance status 0-2, Child Pugh A/B7) were randomised 1:1 to TACE plus low-dose cyclophosphamide (Group 1) or TACE plus low-dose cyclophosphamide plus dendritic cell vaccination (Group 2). Cyclophosphamide was administered on Day 1 and 29 followed by TACE on Day 31 (+/- DC infusion), with further cyclophosphamide on Days 60, 90 and 120 (+/- additional DC infusions on Days 62, 92 and 122). The primary endpoint was progression free survival (PFS) by RECIST v1.1. Secondary endpoints included radiological response by RECIST v1.1, PFS and radiological response according to modified (m) RECIST, overall survival (OS), immune response and toxicity. Target recruitment was 48 evaluable patients (24 patients in each arm) to detect a 20% increase in PFS rate at 1 year (30% vs 50%) with a relaxed one-sided statistical significance level of 20% and 80% power using a logrank test. Results: Between March 2016 and October 2019, 55 patients from 3 UK centres were randomised of whom 48 were evaluable (24 each arm). Median PFS by RECIST criteria was significantly longer in Group 2 compared to Group 1 (18.6 vs 10.4 months: hazard ratio (HR) 0.43, 80% CI -∞-0.59; one-sided p = 0.02). Median PFS using mRECIST criteria showed a similar magnitude of benefit (18.6 vs 10.8 months: HR 0.48, 95% CI 0.22-1.02). Median OS was 25.7 months in Group 2 vs 21.5 months in Group 1 (HR 0.61, 95% CI 0.27-1.38). Group 2 showed a higher overall response rate (complete and partial response) by RECIST (54% vs 29%) and mRECIST (75% vs 54%) and a higher disease control rate (complete and partial response and stable disease) by RECIST (92% vs 67%) and mRECIST (88% vs 67%). Treatment with DC infusions was well tolerated; the most common adverse events were chills (30%), fatigue (22%) and nausea (22%), all of which were low grade. Immune response analyses are currently ongoing. Conclusions: The addition of tumour lysate pulsed DC infusions to treatment with TACE plus low-dose cyclophosphamide significantly increased PFS in patients with HCC. To the best of our knowledge, this is the first randomised study to demonstrate efficacy using DC in HCC. Further investigation of the role of DC infusions in the treatment of HCC are warranted but will need to take into account the current evolving immunotherapy landscape. Clinical trial information: 11889464.

Exosome-related Methods and Potential Use as Vaccines.

Although significant clinical advances have been made in the treatment of cancer using the immune system, discovery of therapeutic cancer vaccines still remains as an area of interest. Development of the method of pulsing dendritic cells with tumor antigens set the stage for the development of cancer vaccines. Exosomes have gained significant interest because of their ability to activate dendritic cells to recognize and kill cancerous cells. Because of their characteristics such as superior biosafety profile to other nanoparticles, exosomes are promising nanocarriers for clinical use, which makes them an attractive candidate for cancer vaccine development. Identification of novel vaccinations for immunoprevention can be studied by exosomes. This chapter describes commonly used methods to isolate and manipulate exosomes.

Identification of Immunogenic MHC Class II Human HER3 Peptides that Mediate Anti-HER3 CD4+ Th1 Responses and Potential Use as a Cancer Vaccine.

The HER3/ERBB3 receptor is an oncogenic receptor tyrosine kinase that forms heterodimers with EGFR family members and is overexpressed in numerous cancers. HER3 overexpression associates with reduced survival and acquired resistance to targeted therapies, making it a potential therapeutic target in multiple cancer types. Here, we report on immunogenic, promiscuous MHC class II-binding HER3 peptides, which can generate HER3-specific CD4+ Th1 antitumor immune responses. Using an overlapping peptide screening methodology, we identified nine MHC class II-binding HER3 epitopes that elicited specific Th1 immune response in both healthy donors and breast cancer patients. Most of these peptides were not identified by current binding algorithms. Homology assessment of amino acid sequence BLAST showed >90% sequence similarity between human and murine HER3/ERBB3 peptide sequences. HER3 peptide-pulsed dendritic cell vaccination resulted in anti-HER3 CD4+ Th1 responses that prevented tumor development, significantly delayed tumor growth in prevention models, and caused regression in multiple therapeutic models of HER3-expressing murine tumors, including mammary carcinoma and melanoma. Tumors were robustly infiltrated with CD4+ T cells, suggesting their key role in tumor rejection. Our data demonstrate that class II HER3 promiscuous peptides are effective at inducing HER3-specific CD4+ Th1 responses and suggest their applicability in immunotherapies for human HER3-overexpressing tumors.

In Vitro Priming of Human T Cells by Dendritic Cells Provides a Screening Tool for Candidate Vaccines for Burkholderia pseudomallei.

Murine dendritic cells, when pulsed with heat-killed Burkholderia pseudomallei and used to immunise naïve mice, have previously been shown to induce protective immunity in vivo. We have now demonstrated the in vitro priming of naïve human T cells against heat-killed B. pseudomallei, by co-culture with syngeneic B. pseudomallei-pulsed dendritic cells. Additionally, we have enriched the DC fraction such that a study of the differential response induced by pulsed DCs of either myeloid or plasmacytoid lineage in syngeneic human T cells was achievable. Whilst both mDCs and pDCs were activated by pulsing, the mDCs contributed the major response to B. pseudomallei with the expression of the migration marker CCR7 and a significantly greater secretion of the proinflammatory TNFα and IL1β. When these DC factions were combined and used to prime syngeneic T cells, a significant proliferation was observed in the CD4+ fraction. Here, we have achieved human T cell priming in vitro with unadjuvanted B. pseudomallei, the causative organism of melioidosis, for which there is currently no approved vaccine. We propose that the approach we have taken could be used to screen for the human cellular response to candidate vaccines and formulations, in order to enhance the cell-mediated immunity required to protect against this intracellular pathogen and potentially more broadly against other, difficult-to-treat intracellular pathogens. To date, the polysaccharide capsule of B. pseudomallei, fused to a standard carrier protein, e.g., Crm, looks a likely vaccine candidate. Dendritic cells (DCs), providing, as they do, the first line of defence to infection, process and present microbial products to the immune system to direct downstream immune responses. Here, we have sought to use DCs ex vivo to identify immunogenic products from heat-killed B. pseudomallei. Using practical volumes of fresh human donor blood, we show that heat-killed B. pseudomallei activated and stimulated the expression of pro-inflammatory cytokines TNF-α, IL-1β and IL-6 from both myeloid and plasmacytoid DCs. Furthermore, B. pseudomallei-pulsed DCs cultured with naïve syngeneic T cells ex vivo, induced the activation and proliferation of the CD4+ T-cell population, which was identified by cell surface marker staining using flow cytometry. Thus, both DC subsets are important for driving primary T helper cell responses to B. pseudomallei in healthy individuals and have the potential to be used to identify immunogenic components of B. pseudomallei for future therapies and vaccines.