Development and Optimization of a GMP-Compliant Manufacturing Process for a Personalized Tumor Lysate Dendritic Cell Vaccine.

With the emergence of immune checkpoint inhibitors and adoptive T-cell therapies, there is a considerable interest in using personalized autologous dendritic cell (DC) vaccines in combination with T cell-targeting immunotherapies to potentially maximize the therapeutic impact of DC vaccines. Here, we describe the development and optimization of a Good Manufacturing Practice (GMP)-compliant manufacturing process based on tumor lysate as a tumor antigen source for the production of an oxidized tumor cell lysate loaded DC (OC-DC) vaccine. The manufacturing process required one day for lysate preparation and six days for OC-DC vaccine production. Tumor lysate production was standardized based on an optimal tumor digestion protocol and the immunogenicity was improved through oxidation using hypochloric acid prior to freeze-thaw cycles resulting in the oxidized tumor cell lysate (OC-L). Next, monocytes were selected using the CliniMACS prodigy closed system and were placed in culture in cell factories in the presence of IL-4 and GM-CSF. Immature DCs were loaded with OC-L and matured using MPLA-IFNγ. After assessing the functionality of the OC-DC cells (IL12p70 secretion and COSTIM assay), the OC-DC vaccine was cryopreserved in multiple doses for single use. Finally, the stability of the formulated doses was tested and validated. We believe this GMP-compliant DC vaccine manufacturing process will facilitate access of patients to personalized DC vaccines, and allow for multi-center clinical trials.

A Phase I/II trial comparing autologous dendritic cell vaccine pulsed either with personalized peptides (PEP-DC) or with tumor lysate (OC-DC) in patients with advanced high-grade ovarian serous carcinoma.

BACKGROUND: Most ovarian cancer patients are diagnosed at a late stage with 85% of them relapsing after surgery and standard chemotherapy; for this reason, new treatments are urgently needed. Ovarian cancer has become a candidate for immunotherapy by reason of their expression of shared tumor-associated antigens (TAAs) and private mutated neoantigens (NeoAgs) and the recognition of the tumor by the immune system. Additionally, the presence of intraepithelial tumor infiltrating lymphocytes (TILs) is associated with improved progression-free and overall survival of patients with ovarian cancer. The aim of active immunotherapy, including vaccination, is to generate a new anti-tumor response and amplify an existing immune response. Recently developed NeoAgs-based cancer vaccines have the advantage of being more tumor specific, reducing the potential for immunological tolerance, and inducing robust immunogenicity. METHODS: We propose a randomized phase I/II study in patients with advanced ovarian cancer to compare the immunogenicity and to assess safety and feasibility of two personalized DC vaccines. After standard of care surgery and chemotherapy, patients will receive either a novel vaccine consisting of autologous DCs pulsed with up to ten peptides (PEP-DC), selected using an agnostic, yet personalized, epitope discovery algorithm, or a sequential combination of a DC vaccine loaded with autologous oxidized tumor lysate (OC-DC) prior to an equivalent PEP-DC vaccine. All vaccines will be administered in combination with low-dose cyclophosphamide. This study is the first attempt to compare the two approaches and to use NeoAgs-based vaccines in ovarian cancer in the adjuvant setting. DISCUSSION: The proposed treatment takes advantage of the beneficial effects of pre-treatment with OC-DC prior to PEP-DC vaccination, prompting immune response induction against a wide range of patient-specific antigens, and amplification of pre-existing NeoAgs-specific T cell clones. Trial registration This trial is already approved by Swissmedic (Ref.: 2019TpP1004) and will be registered at http://www.clinicaltrials.gov before enrollment opens.

A Phase Ib Study of the Combination of Personalized Autologous Dendritic Cell Vaccine, Aspirin, and Standard of Care Adjuvant Chemotherapy Followed by Nivolumab for Resected Pancreatic Adenocarcinoma-A Proof of Antigen Discovery Feasibility in Three Patients.

Despite the promising therapeutic effects of immune checkpoint blockade (ICB), most patients with solid tumors treated with anti-PD-1/PD-L1 monotherapy do not achieve objective responses, with most tumor regressions being partial rather than complete. It is hypothesized that the absence of pre-existing antitumor immunity and/or the presence of additional tumor immune suppressive factors at the tumor microenvironment are responsible for such therapeutic failures. It is therefore clear that in order to fully exploit the potential of PD-1 blockade therapy, antitumor immune response should be amplified, while tumor immune suppression should be further attenuated. Cancer vaccines may prime patients for treatments with ICB by inducing effective anti-tumor immunity, especially in patients lacking tumor-infiltrating T-cells. These "non-inflamed" non-permissive tumors that are resistant to ICB could be rendered sensitive and transformed into "inflamed" tumor by vaccination. In this article we describe a clinical study where we use pancreatic cancer as a model, and we hypothesize that effective vaccination in pancreatic cancer patients, along with interventions that can reprogram important immunosuppressive factors in the tumor microenvironment, can enhance tumor immune recognition, thus enhancing response to PD-1/PD-L1 blockade. We incorporate into the schedule of standard of care (SOC) chemotherapy adjuvant setting a vaccine platform comprised of autologous dendritic cells loaded with personalized neoantigen peptides (PEP-DC) identified through our own proteo-genomics antigen discovery pipeline. Furthermore, we add nivolumab, an antibody against PD-1, to boost and maintain the vaccine's effect. We also demonstrate the feasibility of identifying personalized neoantigens in three pancreatic ductal adenocarcinoma (PDAC) patients, and we describe their optimal incorporation into long peptides for manufacturing into vaccine products. We finally discuss the advantages as well as the scientific and logistic challenges of such an exploratory vaccine clinical trial, and we highlight its novelty.

Personalized Dendritic Cell Vaccines-Recent Breakthroughs and Encouraging Clinical Results.

With the advent of combined immunotherapies, personalized dendritic cell (DC)-based vaccination could integrate the current standard of care for the treatment of a large variety of tumors. Due to their proficiency at antigen presentation, DC are key coordinators of the innate and adaptive immune system, and have critical roles in the induction of antitumor immunity. However, despite proven immunogenicity and favorable safety profiles, DC-based immunotherapies have not succeeded at inducing significant objective clinical responses. Emerging data suggest that the combination of DC-based vaccination with other cancer therapies may fully unleash the potential of DC-based cancer vaccines and improve patient survival. In this review, we discuss the recent efforts to develop innovative personalized DC-based vaccines and their use in combined therapies, with a particular focus on ovarian cancer and the promising results of mutanome-based personalized immunotherapies.

Local endothelial complement activation reverses endothelial quiescence, enabling t-cell homing, and tumor control during t-cell immunotherapy.

Cancer immunotherapy relies upon the ability of T cells to infiltrate tumors. The endothelium constitutes a barrier between the tumor and effector T cells, and the ability to manipulate local vascular permeability could be translated into effective immunotherapy. Here, we show that in the context of adoptive T cell therapy, antitumor T cells, delivered at high enough doses, can overcome the endothelial barrier and infiltrate tumors, a process that requires local production of C3, complement activation on tumor endothelium and release of C5a. C5a, in turn, acts on endothelial cells promoting the upregulation of adhesion molecules and T-cell homing. Genetic deletion of C3 or the C5a receptor 1 (C5aR1), and pharmacological blockade of C5aR1, impaired the ability of T cells to overcome the endothelial barrier, infiltrate tumors, and control tumor progression in vivo, while genetic chimera mice demonstrated that C3 and C5aR1 expression by tumor stroma, and not leukocytes, governs T cell homing, acting on the local endothelium. In vitro, endothelial C3 and C5a expressions were required for endothelial activation by type 1 cytokines. Our data indicate that effective immunotherapy is a consequence of successful homing of T cells in response to local complement activation, which disrupts the tumor endothelial barrier.

Potential approaches for more successful dendritic cell-based immunotherapy.

INTRODUCTION: Dendritic cells (DCs) are the most important antigen-presenting cell population for activating antitumor T-cell responses; therefore, they offer a unique opportunity for specific targeting of tumors. AREAS COVERED: We will discuss the critical factors for the enhancement of DC vaccine efficacy: different DC subsets, types of in vitro DC manufacturing protocol, types of tumor antigen to be loaded and finally different adjuvants for activating them. We will cover potential combinatorial strategies with immunomodulatory therapies: depleting T-regulatory (Treg) cells, blocking VEGF and blocking inhibitory signals. Furthermore, recommendations to incorporate these criteria into DC-based tumor immunotherapy will be suggested. EXPERT OPINION: Monocyte-derived DCs are the most widely used DC subset in the clinic, whereas Langerhans cells and plasmacytoid DCs are two emerging DC subsets that are highly effective in eliciting cytotoxic T lymphocyte responses. Depending on the type of tumor antigens selected for loading DCs, it is important to optimize a protocol that will generate highly potent DCs. The future aim of DC-based immunotherapy is to combine it with one or more immunomodulatory therapies, for example, Treg cell depletion, VEGF blockage and T-cell checkpoint blockage, to elicit the most optimal antitumor immunity to induce long-term remission or even cure cancer patients.

Immunotherapy for ovarian cancer: recent advances and perspectives.

PURPOSE OF REVIEW: Epithelial ovarian cancer is the most frequent cause of gynecologic cancer-related mortality in women, and prognosis for patients with recurrent or metastatic disease is extremely poor. Therefore, there is an enormous unmet need for the development of novel therapies in this indication. Although surgery and chemotherapy can improve survival rates, it is necessary to integrate alternative strategies, such as immunotherapy to improve the outcomes for patients with advanced ovarian cancer. RECENT FINDINGS: We will discuss the rationale of immunotherapy and some of the mechanisms of immunogenicity in ovarian cancer. We will highlight current results with cancer vaccines, adoptive T-cell therapy and immunomodulatory agents and will summarize the immune effects of selected chemotherapeutic agents, radiotherapy and recent results with combinatorial approaches in this disease setting. We will also discuss recent and potential future therapeutic interventions that might circumvent tumor-mediated immunosuppression. SUMMARY: Dramatic increase in the number of immunotherapy clinical trials was seen in the past decade with promising results in enhancing antitumor immune response and cancer vaccine efficacy. The future challenge for immunotherapy against ovarian cancer is to use a combinatorial approach to test rational, potentially synergistic immunotherapy combinations that can induce efficient antitumor immunity and prolong patients' survival.

Ionizing radiation selectively reduces skin regulatory T cells and alters immune function.

The skin serves multiple functions that are critical for life. The protection from pathogens is achieved by a complicated interaction between aggressive effectors and controlling functions that limit damage. Inhomogeneous radiation with limited penetration is used in certain types of therapeutics and is experienced with exposure to solar particle events outside the protection of the Earth's magnetic field. This study explores the effect of ionizing radiation on skin immune function. We demonstrate that radiation, both homogeneous and inhomogeneous, induces inflammation with resultant specific loss of regulatory T cells from the skin. This results in a hyper-responsive state with increased delayed type hypersensitivity in vivo and CD4+ T cell proliferation in vitro. The effects of inhomogeneous radiation to the skin of astronauts or as part of a therapeutic approach could result in an unexpected enhancement in skin immune function. The effects of this need to be considered in the design of radiation therapy protocols and in the development of countermeasures for extended space travel.

A Phase I vaccine trial using dendritic cells pulsed with autologous oxidized lysate for recurrent ovarian cancer.

PURPOSE: Ovarian cancer, like most solid tumors, is in dire need of effective therapies. The significance of this trial lies in its promise to spearhead the development of combination immunotherapy and to introduce novel approaches to therapeutic immunomodulation, which could enable otherwise ineffective vaccines to achieve clinical efficacy. RATIONALE: Tumor-infiltrating T cells have been associated with improved outcome in ovarian cancer, suggesting that activation of antitumor immunity will improve survival. However, molecularly defined vaccines have been generally disappointing. Cancer vaccines elicit a modest frequency of low-to-moderate avidity tumor-specific T-cells, but powerful tumor barriers dampen the engraftment, expansion and function of these effector T-cells in the tumor, thus preventing them from reaching their full therapeutic potential. Our work has identified two important barriers in the tumor microenvironment: the blood-tumor barrier, which prevents homing of effector T cells, and T regulatory cells, which inactivate effector T cells. We hypothesize that cancer vaccine therapy will benefit from combinations that attenuate these two barrier mechanisms. DESIGN: We propose a three-cohort sequential study to investigate a combinatorial approach of a new dendritic cell (DC) vaccine pulsed with autologous whole tumor oxidized lysate, in combination with antiangiogenesis therapy (bevacizumab) and metronomic cyclophosphamide, which impacts Treg cells. INNOVATION: This study uses a novel autologous tumor vaccine developed with 4-day DCs pulsed with oxidized lysate to elicit antitumor response. Furthermore, the combination of bevacizumab with a whole tumor antigen vaccine has not been tested in the clinic. Finally the combination of bevacizumab and metronomic cyclophosphamide in immunotherapy is novel.

Tumour hypoxia promotes tolerance and angiogenesis via CCL28 and T(reg) cells.

Although immune mechanisms can suppress tumour growth, tumours establish potent, overlapping mechanisms that mediate immune evasion. Emerging evidence suggests a link between angiogenesis and the tolerance of tumours to immune mechanisms. Hypoxia, a condition that is known to drive angiogenesis in tumours, results in the release of damage-associated pattern molecules, which can trigger the rejection of tumours by the immune system. Thus, the counter-activation of tolerance mechanisms at the site of tumour hypoxia would be a crucial condition for maintaining the immunological escape of tumours. However, a direct link between tumour hypoxia and tolerance through the recruitment of regulatory cells has not been established. We proposed that tumour hypoxia induces the expression of chemotactic factors that promote tolerance. Here we show that tumour hypoxia promotes the recruitment of regulatory T (T(reg)) cells through induction of expression of the chemokine CC-chemokine ligand 28 (CCL28), which, in turn, promotes tumour tolerance and angiogenesis. Thus, peripheral immune tolerance and angiogenesis programs are closely connected and cooperate to sustain tumour growth.

Effect of solar particle event radiation on gastrointestinal tract bacterial translocation and immune activation.

Space flight conditions within the protection of Earth's gravitational field have been shown to alter immune responses, which could lead to potentially detrimental pathology. An additional risk of extended space travel outside the Earth's gravitational field is the effect of solar particle event (SPE) radiation exposure on the immune system. Organisms that could lead to infection include endogenous, latent viruses, colonizing pathogenics, and commensals, as well as exogenous microbes present in the spacecraft or other astronauts. In this report, the effect of SPE-like radiation on containment of commensal bacteria and the innate immune response induced by its breakdown was investigated at the radiation energies, doses and dose rates expected during an extravehicular excursion outside the Earth's gravitational field. A transient increase in serum lipopolysaccharide was observed 1 day after irradiation and was accompanied by an increase in acute-phase reactants and circulating proinflammatory cytokines, indicating immune activation. Baseline levels were reestablished by 5 days postirradiation. These findings suggest that astronauts exposed to SPE radiation could have impaired containment of colonizing bacteria and associated immune activation.

Active Notch1 confers a transformed phenotype to primary human melanocytes.

The importance of mitogen-activated protein kinase signaling in melanoma is underscored by the prevalence of activating mutations in N-Ras and B-Raf, yet clinical development of inhibitors of this pathway has been largely ineffective, suggesting that alternative oncogenes may also promote melanoma. Notch is an interesting candidate that has only been correlated with melanoma development and progression; a thorough assessment of tumor-initiating effects of activated Notch on human melanocytes would clarify the mounting correlative evidence and perhaps identify a novel target for an otherwise untreatable disease. Analysis of a substantial panel of cell lines and patient lesions showed that Notch activity is significantly higher in melanomas than their nontransformed counterparts. The use of a constitutively active, truncated Notch transgene construct (N(IC)) was exploited to determine if Notch activation is a "driving" event in melanocytic transformation or instead a "passenger" event associated with melanoma progression. N(IC)-infected melanocytes displayed increased proliferative capacity and biological features more reminiscent of melanoma, such as dysregulated cell adhesion and migration. Gene expression analyses supported these observations and aided in the identification of MCAM, an adhesion molecule associated with acquisition of the malignant phenotype, as a direct target of Notch transactivation. N(IC)-positive melanocytes grew at clonal density, proliferated in limiting media conditions, and also exhibited anchorage-independent growth, suggesting that Notch alone is a transforming oncogene in human melanocytes, a phenomenon not previously described for any melanoma oncogene. This new information yields valuable insight into the basic epidemiology of melanoma and launches a realm of possibilities for drug intervention in this deadly disease.

Role of vascular leukocytes in ovarian cancer neovascularization.

Vascular leukocytes are a unique population of CD45+ VE-cadherin+ cells with diverse functions. VLCs are capable of antigen presentation, as well as formation of endothelial-like structures in vitro and in vivo. VLCs are largely present among CD45+ cells infiltrating human ovarian carcinomas and are highly represented in the beta-defensin-VEGF-ID8 syngenic mouse model. Vascular leukocytes are a new and promising novel therapeutic target for anti-angiogenic therapy. Their unique mechanism merits thorough and extensive exploration in the future.

Endothelin B receptor mediates the endothelial barrier to T cell homing to tumors and disables immune therapy.

In spite of their having sufficient immunogenicity, tumor vaccines remain largely ineffective. The mechanisms underlying this lack of efficacy are still unclear. Here we report a previously undescribed mechanism by which the tumor endothelium prevents T cell homing and hinders tumor immunotherapy. Transcriptional profiling of microdissected tumor endothelial cells from human ovarian cancers revealed genes associated with the absence or presence of tumor-infiltrating lymphocytes (TILs). Overexpression of the endothelin B receptor (ET(B)R) was associated with the absence of TILs and short patient survival time. The ET(B)R inhibitor BQ-788 increased T cell adhesion to human endothelium in vitro, an effect countered by intercellular adhesion molecule-1 (ICAM-1) blockade or treatment with NO donors. In mice, ET(B)R neutralization by BQ-788 increased T cell homing to tumors; this homing required ICAM-1 and enabled tumor response to otherwise ineffective immunotherapy in vivo without changes in systemic antitumor immune response. These findings highlight a molecular mechanism with the potential to be pharmacologically manipulated to enhance the efficacy of tumor immunotherapy in humans.

Notch1 signaling promotes primary melanoma progression by activating mitogen-activated protein kinase/phosphatidylinositol 3-kinase-Akt pathways and up-regulating N-cadherin expression.

Cellular signaling mediated by Notch receptors results in coordinated regulation of cell growth, survival, and differentiation. Aberrant Notch activation has been linked to a variety of human neoplasms. Here, we show that Notch1 signaling drives the vertical growth phase (VGP) of primary melanoma toward a more aggressive phenotype. Constitutive activation of Notch1 by ectopic expression of the Notch1 intracellular domain enables VGP primary melanoma cell lines to proliferate in a serum-independent and growth factor-independent manner in vitro and to grow more aggressively with metastatic activity in vivo. Notch1 activation also enhances tumor cell survival when cultured as three-dimensional spheroids. Such effects of Notch signaling are mediated by activation of the mitogen-activated protein kinase (MAPK) and Akt pathways. Both pathways are activated in melanoma cells following Notch1 pathway activation. Inhibition of either the MAPK or the phosphatidylinositol 3-kinase (PI3K)-Akt pathway reverses the Notch1 signaling-induced tumor cell growth. Moreover, the growth-promoting effect of Notch1 depends on mastermind-like 1. We further showed that Notch1 activation increases tumor cell adhesion and up-regulates N-cadherin expression. Our data show regulation of MAPK/PI3K-Akt pathway activities and expression of N-cadherin by the Notch pathway and provide a mechanistic basis for Notch signaling in the promotion of primary melanoma progression.

Inhibition of endothelial cell proliferation by Notch1 signaling is mediated by repressing MAPK and PI3K/Akt pathways and requires MAML1.

The requirement for Notch signaling in vasculogenesis and angiogenesis is well documented. In a previous study, we showed that activation of the Notch pathway in endothelial cells induces differentiation-associated growth arrest; however, the underlying mechanism remains to be elucidated. Here, we show that activation of the Notch pathway by either stimulation of cell surface Notch receptors with crosslinked soluble delta-like 4 (sDll4)/Jagged1 (sJag1) or constitutive expression of the Notch1 intracellular domain (N(IC)) suppresses endothelial cell proliferation. This suppression is mediated by the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt pathways. Following Notch1 activation, both pathways were suppressed in endothelial cells, and alterations in MAPK or PI3K/Akt pathway activity reversed Notch1-induced growth inhibition. Furthermore, we found the effect of Notch1 on endothelial cells to require Mastermind-like (MAML). Overexpression of a dominant-negative mutant of MAML1 antagonized the effects of activated Notch1 on the MAPK and PI3K/Akt pathways. Ectopic expression of Hairy/Enhancer of Split 1 (HES1) consistently reproduced the inhibitory effect of N(IC) on endothelial cell proliferation. Together, our data demonstrate that the Notch/MAML-HES signaling cascade can regulate both MAPK and PI3K/Akt pathways, which suggests a molecular mechanism for the inhibitory effect of Notch signaling on endothelial cell proliferation.

Activation of Notch1 signaling is required for beta-catenin-mediated human primary melanoma progression.

Notch is a highly conserved transmembrane receptor that determines cell fate. Notch signaling denotes cleavage of the Notch intracellular domain, its translocation to the nucleus, and subsequent activation of target gene transcription. Involvement of Notch signaling in several cancers is well known, but its role in melanoma remains poorly characterized. Here we show that the Notch1 pathway is activated in human melanoma. Blocking Notch signaling suppressed whereas constitutive activation of the Notch1 pathway enhanced primary melanoma cell growth both in vitro and in vivo yet had little effect on metastatic melanoma cells. Activation of Notch1 signaling enabled primary melanoma cells to gain metastatic capability. Furthermore, the oncogenic effect of Notch1 on primary melanoma cells was mediated by beta-catenin, which was upregulated following Notch1 activation. Inhibiting beta-catenin expression reversed Notch1-enhanced tumor growth and metastasis. Our data therefore suggest a beta-catenin-dependent, stage-specific role for Notch1 signaling in promoting the progression of primary melanoma.