Evaluation of ipilimumab in combination with allogeneic pancreatic tumor cells transfected with a GM-CSF gene in previously treated pancreatic cancer. J Immunother. 2013;36:382-389. [PMID: 23924790 DOI: 10.1097/cji.0b013e31829fb7a2]

Challenges and Perspectives for Immunotherapy in Adenocarcinoma of the Pancreas: The Cancer Immunity Cycle

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with a devastating 5-year overall survival of only approximately 7%. Although just 4% of all malignant diseases are accounted to PDAC, it will become the second leading cause of cancer-related deaths before 2030. Immunotherapy has proven to be a promising therapeutic option in various malignancies such as melanoma, non-small cell lung cancer (NSCLC), microsatellite instability-high gastrointestinal cancer, urinary tract cancer, kidney cancer, and others. In this review, we summarize recent findings about immunological aspects of PDAC with the focus on the proposed model of the "cancer immunity cycle". By this model, a deeper understanding of the underlying mechanism in achieving a T-cell response against cancer cells is provided. There is currently great interest in the field around designing novel immunotherapy combination studies for PDAC based on a sound understanding of the underlying immunobiology.

How does the tumor microenvironment play a role in hepatobiliary tumors?

The tumor microenvironment (TME) is defined as the structural and dynamic network of cellular and non-cellular interactions between malignant cells and the surrounding non-malignant matrix. Hepatocellular carcinoma (HCC) and pancreatic ductal adenocarcinoma (PDAC) are two of the most challenging gastrointestinal malignancies. Despite clinical advancements in understanding tumor biology and growth of the chemotherapeutic industry, there have been no corresponding improvements in prognosis and overall survival of HCC and PDAC. Both of these cancers have a very intimate relationship with their surrounding environment; the TME is thought to actively participate in initiating and sustaining these malignancies. Individual TME constituents play a vital role in chemoresistance and recurrence after surgery and have been established as independent prognostic factors. This review article will highlight the diverse structural components, key signaling pathways, and extracellular matrices of HCC and PDAC and discuss their crosstalk with tumor cells to promote growth and metastasis. The article will also summarize the latest laboratory and clinical research based on therapeutic targets identified within the TME of both HCC and PDAC.

Novel agents for pancreatic ductal adenocarcinoma: emerging therapeutics and future directions

A poor prognosis of pancreatic ductal adenocarcinoma (PDAC) associated with chemoresistance has not changed for the past three decades. A multidisciplinary diagnosis followed by surgery and chemo(radiation)therapy is the main treatment approach. However, gemcitabine- and 5-fluorouracil-based therapies did not present satisfying outcomes. Novel regimens targeting pancreatic cancer cells, the tumor microenvironment, and immunosuppression are emerging. Biomarkers concerning the treatment outcome and patient selection are being discovered in preclinical or clinical studies. Combination therapies of classic chemotherapeutic drugs and novel agents or novel therapeutic combinations might bring hope to the dismal prognosis for PDAC patients.

Precision Immuno-Oncology: Prospects of Individualized Immunotherapy for Pancreatic Cancer

Pancreatic cancer, most commonly referring to pancreatic ductal adenocarcinoma (PDAC), remains one of the most deadly diseases, with very few effective therapies available. Emerging as a new modality of modern cancer treatments, immunotherapy has shown promises for various cancer types. Over the past decades, the potential of immunotherapy in eliciting clinical benefits in pancreatic cancer have also been extensively explored. It has been demonstrated in preclinical studies and early phase clinical trials that cancer vaccines were effective in eliciting anti-tumor immune response, but few have led to a significant improvement in survival. Despite the fact that immunotherapy with checkpoint blockade (e.g., anti-cytotoxic T-lymphocyte antigen 4 [CTLA-4] and anti-programmed cell death 1 [PD-1]/PD-L1 antibodies) has shown remarkable and durable responses in various cancer types, the application of checkpoint inhibitors in pancreatic cancer has been disappointing so far. It may, in part, due to the unique tumor microenvironment (TME) of pancreatic cancer, such as existence of excessive stromal matrix and hypovascularity, creating a TME of strong inhibitory signaling circuits and tremendous physical barriers for immune agent infiltration. This informs on the need for combination therapy approaches to engender a potent immune response that can translate to clinical benefits. On the other hand, lack of effective and validated biomarkers to stratify subgroup of patients who can benefit from immunotherapy poses further challenges for the realization of precision immune-oncology. Future studies addressing issues such as TME modulation, biomarker identification and therapeutic combination are warranted. In this review, advances in immunotherapy for pancreatic cancer were discussed and opportunities as well as challenges for personalized immune-oncology were addressed.

Combination Immunotherapy of MUC1 mRNA Nano-vaccine and CTLA-4 Blockade Effectively Inhibits Growth of Triple Negative Breast Cancer

Triple negative breast cancer (TNBC), which constitutes 10%-20% of all breast cancers, is associated with aggressive progression, a high rate of metastasis, and poor prognosis. The treatment of patients with TNBC remains a great clinical challenge. Preclinical reports support the combination immunotherapy of cancer vaccines and immune checkpoint blockades in non-immunogenic tumors. In this study, we constructed nanoparticles (NPs) to deliver an mRNA vaccine encoding tumor antigen MUC1 to dendritic cells (DCs) in lymph nodes to activate and expand tumor-specific T cells. An anti-CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) monoclonal antibody was combined with the mRNA vaccine to enhance the anti-tumor benefits. In vivo studies demonstrated that the NP-based mRNA vaccine, targeted to mannose receptors on DCs, could successfully express tumor antigen in the DCs of the lymph node; that the NP vaccine could induce a strong, antigen-specific, in vivo cytotoxic T lymphocyte response against TNBC 4T1 cells; and that combination immunotherapy of the vaccine and anti-CTLA-4 monoclonal antibody could significantly enhance anti-tumor immune response compared to the vaccine or monoclonal antibody alone. These data support both the NP as a carrier for delivery of mRNA vaccine and a potential combination immunotherapy of the NP-based mRNA vaccine and the CTLA-4 inhibitor for TNBC.

Immune Evasion in Pancreatic Cancer: From Mechanisms to Therapy

Pancreatic ductal adenocarcinoma (PDA), the most frequent type of pancreatic cancer, remains one of the most challenging problems for the biomedical and clinical fields, with abysmal survival rates and poor therapy efficiency. Desmoplasia, which is abundant in PDA, can be blamed for much of the mechanisms behind poor drug performance, as it is the main source of the cytokines and chemokines that orchestrate rapid and silent tumor progression to allow tumor cells to be isolated into an extensive fibrotic reaction, which results in inefficient drug delivery. However, since immunotherapy was proclaimed as the breakthrough of the year in 2013, the focus on the stroma of pancreatic cancer has interestingly moved from activated fibroblasts to the immune compartment, trying to understand the immunosuppressive factors that play a part in the strong immune evasion that characterizes PDA. The PDA microenvironment is highly immunosuppressive and is basically composed of T regulatory cells (Tregs), tumor-associated macrophages (TAMs), and myeloid-derived suppressive cells (MDSCs), which block CD8⁺ T-cell duties in tumor recognition and clearance. Interestingly, preclinical data have highlighted the importance of this immune evasion as the source of resistance to single checkpoint immunotherapies and cancer vaccines and point at pathways that inhibit the immune attack as a key to solve the therapy puzzle. Here, we will discuss the molecular mechanisms involved in PDA immune escape as well as the state of the art of the PDA immunotherapy.

Ipilimumab for the treatment of metastatic prostate cancer

INTRODUCTION

Immunotherapy with checkpoint inhibitors is beginning to be recognized as a valid weapon for the treatment of metastatic prostate cancer (PCa) when chemotherapy fails. Ipilimumab (ipi) is a fully humanized monoclonal antibody that blocks the activity of CTLA4. It also has a molecular weight of 148 kDa and is water-soluble at physiological pH. Ipi was first approved by the FDA for the treatment of malignant melanoma and is currently being studied in metastatic castration-resistant prostate cancer, with promising early results. Areas covered: The aim of this review is to collate the most significant preclinical and clinical studies available that look at ipi to propose new strategies for the future. Expert opinion: Additional studies are required to reduce toxicity and increase the activity of ipi in PCa. A possible strategy is to combine ipi with standard anti-cancer therapeutics such as vaccines, PDL1 inhibitors, antiandrogen drugs, and chemotherapy agents. Several initial results have suggested that combination strategies are useful to increase the activity in mCRPC, even if the toxicity of the treatment can increase. The activity of combined treatments is still not predictable, but considering the ongoing studies, we believe that they have good potential that will lead to the discovery of an optimal therapeutic strategy.

The Toll like receptor 4 ligand cold-inducible RNA-binding protein as vaccination platform against cancer

Tumor infiltrating lymphocytes have been associated with a better prognostic and with higher response rates in patients treated with checkpoint inhibiting antibodies, suggesting that strategies promoting tumor inflammation may enhance the efficacy of these currently available therapies. Our aim was thus to develop a new vaccination platform based on cold-inducible RNA binding protein (CIRP), an endogenous TLR4 ligand generated during inflammatory processes, and characterize whether it was amenable to combination with checkpoint inhibitors. In vitro, CIRP induced dendritic cell activation, migration and enhanced presentation of CIRP-bound antigens to T-cells. Accordingly, antigen conjugation to CIRP conferred immunogenicity, dependent on immunostimulatory and antigen-targeting capacities of CIRP. When applied in a therapeutic setting, vaccination led to CD8-dependent tumor rejection in several tumor models. Moreover, immunogenicity of this vaccination platform was enhanced not only by combination with additional adjuvants, but also with antibodies blocking PD-1/PD-L1, CTLA-4 and IL-10, immunosuppressive molecules usually present in the tumor environment and also induced by the vaccine. Therefore, priming with a CIRP-based vaccine combined with immune checkpoint-inhibiting antibodies rejected established B16-OVA tumors. Finally, equivalent activation and T-cell stimulatory effects were observed when using CIRP in vitro with human cells, suggesting that CIRP-based vaccination strategies could be a valuable clinical tool to include in combinatorial immunotherapeutic strategies in cancer patients.

Emerging trends in the immunotherapy of pancreatic cancer

Pancreatic cancer (PC) is the fourth leading cause of cancer-related deaths in the U.S., claiming approximately 43,000 lives every year. Much like other solid tumors, PC evades the host immune surveillance by manipulating immune cells to establish an immunosuppressive tumor microenvironment (TME). Therefore, targeting and reinstating the patient's immune system could serve as a powerful therapeutic tool. Indeed, immunotherapy has emerged in recent years as a potential adjunct treatment for solid tumors including PC. Immunotherapy modulates the host's immune response to tumor-associated antigens (TAAs), eradicates cancer cells by reducing host tolerance to TAAs and provides both short- and long-term protection against the disease. Passive immunotherapies like monoclonal antibodies or engineered T-cell based therapies directly target tumor cells by recognizing TAAs. Active immunotherapies, like cancer vaccines, on the other hand elicit a long-lasting immune response via activation of the patient's immune cells against cancer cells. Several immunotherapy strategies have been tested for anti-tumor responses alone and in combination with standard care in multiple preclinical and clinical studies. In this review, we discuss various immunotherapy strategies used currently and their efficacy in abrogating self-antigen tolerance and immunosuppression, as well as their ability to eradicate PC.

Clinical evaluation of macrophages in cancer: role in treatment, modulation and challenges

The focus of immunotherapeutics has been placed firmly on anti-tumour T cell responses. Significant progress has been made in the treatment of both local and systemic malignancies, but low response rates and rising toxicities are limiting this approach. Advancements in the understanding of tumour immunology are opening up a new range of therapeutic targets, including immunosuppressive factors in the tumour microenvironment. Macrophages are a heterogeneous group of cells that have roles in innate and adaptive immunity and tissue repair, but become co-opted by tumours to support tumour growth, survival, metastasis and immunosuppression. Macrophages also support tumour resistance to conventional therapy. In preclinical models, interference with macrophage migration, macrophage depletion and macrophage re-education have all been shown to reduce tumour growth and support anti-tumour immune responses. Here we discuss the role of macrophages in prognosis and sensitivity to therapy, while examining the significant progress which has been made in modulating the behaviour of these cells in cancer patients.

CTLA-4/CD80 pathway regulates T cell infiltration into pancreatic cancer

The ability of some tumors to exclude effector T cells represents a major challenge to immunotherapy. T cell exclusion is particularly evident in pancreatic ductal adenocarcinoma (PDAC), a disease where blockade of the immune checkpoint molecule CTLA-4 has not produced significant clinical activity. In PDAC, effector T cells are often scarce within tumor tissue and confined to peritumoral lymph nodes and lymphoid aggregates. We hypothesized that CTLA-4 blockade, despite a lack of clinical efficacy seen thus far in PDAC, might still alter T cell immunobiology, which would have therapeutic implications. Using clinically relevant genetic models of PDAC, we found that regulatory T cells (Tregs), which constitutively express CTLA-4, accumulate early during tumor development but are largely confined to peritumoral lymph nodes during disease progression. Tregs were observed to regulate CD4+, but not CD8+, T cell infiltration into tumors through a CTLA-4/CD80 dependent mechanism. Disrupting CTLA-4 interaction with CD80 was sufficient to induce CD4 T cell infiltration into tumors. These data have important implications for T cell immunotherapy in PDAC and demonstrate a novel role for CTLA-4/CD80 interactions in regulating T cell exclusion. In addition, our findings suggest distinct mechanisms govern CD4+ and CD8+ T cell infiltration in PDAC.

Immunotherapy in pancreatic ductal adenocarcinoma: an emerging entity?

The genomic-plasticity of the immune system creates a broad immune repertoire engaged to tackle cancer cells. Promising clinical activity has been observed with several immune therapy strategies in solid tumors including melanoma, lung, kidney, and bladder cancers, albeit as yet immunotherapy-based treatment approaches in pancreatic ductal adenocarcinoma (PDAC) remain to have proven value. While translational and early clinical studies have demonstrated activation of antitumor immunity, most recent late-phase clinical trials have not confirmed the early promise in PDAC except in MSI-High PDAC patients. These results may in part be explained by multiple factors, including the poorly immunogenic nature of PDAC along with immune privilege, the complex tumor microenvironment, and the genetic plasticity of PDAC cells. These challenges have led to disappointments in the field, nonetheless they have also advanced our understanding that may tailor the future steps for immunotherapy for PDAC. Therefore, there is significant hope that progress is on the horizon.

Deploying Immunotherapy in Pancreatic Cancer: Defining Mechanisms of Response and Resistance

The immune reaction to pancreatic ductal adenocarcinoma (PDAC) is a strong prognostic determinant of clinical outcomes and may be a promising therapeutic target. We use multiplex immunohistochemistry to illustrate distinct patterns of T-cell and myeloid cell infiltration seen in PDAC that have therapeutic implications and discuss the current state of immunotherapy in this disease. Based on collective findings from clinical and preclinical studies, two conceptual models have emerged for applying immunotherapy in PDAC that involve (1) restoring elements of T-cell immunosurveillance and (2) redirecting myeloid cells to condition tumors with increased sensitivity to cytotoxic therapies. Overall, the success of immunotherapy in PDAC will most likely rely on strategic combinations of therapies that are informed by well-designed correlative analyses that consider the spatial heterogeneity of immune responses detected in malignant tissues.

Cancer vaccine strategies: translation from mice to human clinical trials

We translated two cancer vaccine strategies from mice into human clinical trials. (1) In preclinical studies on TARP, an antigen expressed in most prostate cancers, we mapped epitopes presented by HLA-A*0201, modified them to increase affinity and immunogenicity in HLA transgenic mice, and induced human T cells that killed human cancer cells ("epitope enhancement"). In a clinical trial, HLA-A2⁺ prostate cancer patients with PSA biochemical recurrence (Stage D0) were vaccinated with two peptides either in Montanide-ISA51 or on autologous dendritic cells (DCs). In stage D0, the Prostate-Specific Antigen (PSA) slope is prognostic of time to radiographic evidence of metastases and death. With no difference between arms, 74% of combined subjects had a decreased PSA slope at 1 year compared to their own baseline slopes (p = 0.0004). For patients vaccinated with DCs, response inversely correlated with a tolerogenic DC signature. A randomized placebo-controlled phase II trial is underway. (2) HER2 is a driver surface oncogene product expressed in multiple tumors. We made an adenoviral vector vaccine expressing the extracellular and transmembrane domains of HER2 and cured mice with large established HER2⁺ tumors, dependent on antibodies to HER2, not T cells. The mechanism differed from that of trastuzumab. We tested a human version in advanced metastatic cancer patients naïve to HER2-directed therapies. At the second and third dose levels, 45% of evaluable patients showed clinical benefit. Circulating tumor cells also declined in some vaccinated patients. Thus, cancer vaccines developed in mice were successfully translated to humans with promising early results.

Focused ultrasound for immuno-adjuvant treatment of pancreatic cancer: An emerging clinical paradigm in the era of personalized oncotherapy

Current clinical treatment regimens, including many emergent immune strategies (e.g., checkpoint inhibitors) have done little to affect the devastating course of pancreatic ductal adenocarcinoma (PDA). Clinical trials for PDA often employ multi-modal treatment, and have started to incorporate stromal-targeted therapies, which have shown promising results in early reports. Focused ultrasound (FUS) is one such therapy that is uniquely equipped to address local and systemic limitations of conventional cancer therapies as well as emergent immune therapies for PDA. FUS methods can non-invasively generate mechanical and/or thermal effects that capitalize on the unique oncogenomic/proteomic signature of a tumor. Potential benefits of FUS therapy for PDA include: (1) emulsification of targeted tumor into undenatured antigens in situ, increasing dendritic cell maturation, and increasing intra-tumoral CD8+/ T regulatory cell ratio and CD8+ T cell activity; (2) reduction in intra-tumoral hypoxic stress; (3) modulation of tumor cell membrane protein localization to enhance immunogenicity; (4) modulation of the local cytokine milieu toward a Th1-type inflammatory profile; (5) up-regulation of local chemoattractants; (6) remodeling the tumor stroma; (7) localized delivery of exogenously packaged immune-stimulating antigens, genes and therapeutic drugs. While not all of these results have been studied in experimental PDA models to date, the principles garnered from other solid tumor and disease models have direct relevance to the design of optimal FUS protocols for PDA. In this review, we address the pertinent limitations in current and emergent immune therapies that can be improved with FUS therapy for PDA.

Undifferentiated Pancreatic Carcinomas Display Enrichment for Frequency and Extent of PD-L1 Expression by Tumor Cells

OBJECTIVES

Programmed death ligand 1 (PD-L1) expression in pancreatic ductal adenocarcinoma (PDA) has been described, but unselected PDAs have shown limited clinical responsiveness to anti-programmed death 1 (PD-1)/PD-L1 therapy.

METHODS

We studied 24 cases of undifferentiated pancreatic carcinoma (UPC) using immunohistochemistry for PD-L1 (E1L3N clone), CD3, CD20, CD68, and DNA mismatch repair proteins in this study. Slides were scored for extent of PD-L1 expression on tumor cells and tumor-infiltrating immune cells.

RESULTS

PD-L1 expression was more frequent in UPCs than in PDAs (63% vs 15%, P < .01). The extent of PD-L1 expression was greater in UPCs, with 13 (87%) of 15 cases containing 10% or more positive tumor cells compared with three of seven PDAs (P = .05). Both tumor groups showed similar numbers of tumor-infiltrating T cells, B cells, and macrophages.

CONCLUSIONS

UPC is enriched for PD-L1 expression in frequency and extent, relative to conventional PDA. Anti-PD-1/PD-L1 agents may represent a valuable therapeutic approach for this subset of highly aggressive pancreatic carcinoma.

Langerhans-type dendritic cells electroporated with TRP-2 mRNA stimulate cellular immunity against melanoma: Results of a phase I vaccine trial

Purpose: We conducted a phase I vaccine trial to determine safety, toxicity, and immunogenicity of autologous Langerhans-type dendritic cells (LCs), electroporated with murine tyrosinase-related peptide-2 (mTRP2) mRNA in patients with resected AJCC stage IIB, IIC, III, or IV (MIa) melanoma. Experimental Design: Nine patients received a priming immunization plus four boosters at three week intervals. Vaccines comprised 10 × 10⁶ mRNA-electroporated LCs, based on absolute number of CD83⁺CD86^brightHLA-DR^brightCD14^neg LCs by flow cytometry. Initial vaccines used freshly generated LCs, whereas booster vaccines used viably thawed cells from the cryopreserved initial product. Post-vaccination assessments included evaluation of delayed-type hypersensitivity (DTH) reactions after booster vaccines and immune response assays at one and three months after the final vaccine. Results: All patients developed mild DTH reactions at injection sites after booster vaccines, but there were no toxicities exceeding grade 1 (CTCAE, v4.0). At one and three months post-vaccination, antigen-specific CD4 and CD8 T cells increased secretion of proinflammatory cytokines (IFN-γ, IL-2, and TNF-α), above pre-vaccine levels, and also upregulated the cytotoxicity marker CD107a. Next-generation deep sequencing of the TCR-V-β CDR3 documented fold-increases in clonality of 2.11 (range 0.85-3.22) for CD4 and 2.94 (range 0.98-9.57) for CD8 T cells at one month post-vaccines. Subset analyses showed overall lower fold-increases in clonality in three patients who relapsed (CD4: 1.83, CD8: 1.54) versus non-relapsed patients (CD4: 2.31, CD8: 3.99). Conclusions: TRP2 mRNA-electroporated LC vaccines are safe and immunogenic. Responses are antigen-specific in terms of cytokine secretion, cytolytic degranulation, and increased TCR clonality, which correlates with clinical outcomes.

Cancer vaccines: Enhanced immunogenic modulation through therapeutic combinations

Therapeutic cancer vaccines have gained significant popularity in recent years as new approaches for specific oncologic indications emerge. Three therapeutic cancer vaccines are FDA approved and one is currently approved by the EMA as monotherapy with modest treatment effects. Combining therapeutic cancer vaccines with other treatment modalities like radiotherapy (RT), hormone therapy, immunotherapy, and/or chemotherapy have been investigated as a means to enhance immune response and treatment efficacy. There is growing preclinical and clinical data that combination of checkpoint inhibitors and vaccines can induce immunogenic intensification with favorable outcomes. Additionally, novel methods for identifying targetable neoantigens hold promise for personalized vaccine development. In this article, we review the rationale for various therapeutic combinations, clinical trial experiences, and future directions. We also highlight the most promising developments that could lead to approval of novel therapeutic cancer vaccines.

New Combination Strategies Using Programmed Cell Death 1/Programmed Cell Death Ligand 1 Checkpoint Inhibitors as a Backbone

The discovery of immune checkpoints and subsequent clinical development of checkpoint inhibitors have revolutionized the field of oncology. The durability of the antitumor immune responses has raised the hope for long-term patient survival and potential cure; however, currently, only a minority of patients respond. Combination strategies to help increase antigen release and T-cell priming, promote T-cell activation and homing, and improve the tumor immune microenvironment, all guided by predictive biomarkers, can help overcome the tumor immune-evasive mechanisms and maximize efficacy to ultimately benefit the majority of patients. Great challenges remain because of the complex underlying biology, unpredictable toxicity, and accurate assessment of response. Carefully designed clinical trials guided by translational studies of paired biopsies will be key to develop reliable predictive biomarkers to choose which patients would most likely benefit from each strategy.

Current challenges in optimizing systemic therapy for patients with pancreatic cancer: expert perspectives from the Australasian Gastrointestinal Trials Group (AGITG) with invited international faculty

INTRODUCTION

Despite recent progress, the outlook for most patients with pancreatic cancer remains poor. There is variation in how patients are managed globally due to differing interpretations of the evidence, partly because studies in this disease are challenging to undertake. This article collates the evidence upon which current best practice is based and offers an expert opinion from an international faculty on how latest developments should influence current treatment paradigms. Areas covered: Optimal chemotherapy for first and subsequent lines of therapy; optimal management of locally advanced, non-metastatic cancer including the role of neoadjuvant chemo(radio)therapy, current evidence for adjuvant chemotherapy, major advances in pancreatic cancer genomics and challenges in supportive care particularly relevant to patients with pancreatic cancer. For each section, literature was reviewed by comprehensive search techniques, including clinical trial websites and abstracts from international cancer meetings. Expert commentary: For each section, a commentary is provided. Overall the challenges identified were: difficulties in diagnosing pancreatic cancer early, challenges for performing randomised clinical trials in all stages of the disease, some progress in systemic therapy with new agents and in identifying molecular subtypes that may be clinically relevant and move towards personalized therapy, but still, pancreatic cancer remains a very poor prognosis cancer with significant palliative care needs.

Immune Modulation Therapy and Imaging: Workshop Report

A workshop at the National Cancer Institute on May 2, 2016, considered the current state of imaging in assessment of immunotherapy. Immunotherapy has shown some remarkable and prolonged responses in the treatment of tumors. However, responses are variable and frequently delayed, complicating the evaluation of new immunotherapy agents and customizing treatment for individual patients. Early anatomic imaging may show that a tumor has increased in size, but this could represent pseudoprogression. On the basis of imaging, clinicians must decide if they should stop, pause, or continue treatment. Other imaging technologies and approaches are being developed to improve the measurement of response in patients receiving immunotherapy. Imaging methods that are being evaluated include radiomic methods using CT, MRI, and ¹⁸F-FDG PET, as well as new radiolabeled small molecules, antibodies, and antibody fragments to image the tumor microenvironment, immune status, and changes over the course of therapy. Current studies of immunotherapy can take advantage of these available imaging options to explore and validate their use. Collection of CT, PET, and MR images along with outcomes from trials is critical to develop improved methods of assessment.

Host controls of HIV broadly neutralizing antibody development

Induction of broadly neutralizing antibodies (bNAbs) is a major goal of HIV vaccine development. BNAbs are made during HIV infection by a subset of individuals but currently cannot be induced in the setting of vaccination. Considerable progress has been made recently in understanding host immunologic controls of bNAb induction and maturation in the setting of HIV infection, and point to key roles for both central and peripheral immunologic tolerance mechanisms in limiting bnAb development. Immune tolerance checkpoint inhibition has been transformative in promotion of anti-tumor CD8 T-cell responses in the treatment of certain malignancies. Here, we review the evidence for host controls of bNAb responses, and discuss strategies for the transient modulation of immune responses with vaccines toward the goal of enhancing germinal center B-cell responses to favor bNAb B-cell lineages and to foster their maturation to full neutralization potency.

Seed-in-Soil: Pancreatic Cancer Influenced by Tumor Microenvironment

Pancreatic ductal adenocarcinoma is a fatal malignancy with a five-year survival rate lower than 7%, and most patients dying within six months of diagnosis. The factors that contribute to the aggressiveness of the disease include, but are not limited to: late diagnosis, prompt metastasis to adjacent vital organs, poor response, and resistance to anticancer treatments. This malignancy is uniquely associated with desmoplastic stroma that accounts for 80% of tumor mass. Understanding the biology of stroma can aid the discovery of innovative strategies for eradicating this lethal cancer in the future. This review highlights the critical components in the stroma and how they interact with the cancer cells to convey the devastating tumor progression.

Neoepitopes as cancer immunotherapy targets: key challenges and opportunities

Over the last half century, it has become well established that cancers can elicit a host immune response that can target them with high specificity. Only within the last decade, with the advances in high-throughput gene sequencing and bioinformatics approaches, are we now on the forefront of harnessing the host's immune system to treat cancer. Recently, some strides have been taken toward understanding effective tumor-specific MHC I restricted epitopes or neoepitopes. However, many fundamental questions still remain to be addressed before this therapy can live up to its full clinical potential. In this review, we discuss the major hurdles that lie ahead and the work being done to address them.

Pancreatic Ductal Adenocarcinoma: Current and Evolving Therapies

Pancreatic ductal adenocarcinoma (PDAC), which constitutes 90% of pancreatic cancers, is the fourth leading cause of cancer-related deaths in the world. Due to the broad heterogeneity of genetic mutations and dense stromal environment, PDAC belongs to one of the most chemoresistant cancers. Most of the available treatments are palliative, with the objective of relieving disease-related symptoms and prolonging survival. Currently, available therapeutic options are surgery, radiation, chemotherapy, immunotherapy, and use of targeted drugs. However, thus far, therapies targeting cancer-associated molecular pathways have not given satisfactory results; this is due in part to the rapid upregulation of compensatory alternative pathways as well as dense desmoplastic reaction. In this review, we summarize currently available therapies and clinical trials, directed towards a plethora of pathways and components dysregulated during PDAC carcinogenesis. Emerging trends towards targeted therapies as the most promising approach will also be discussed.

Overcoming the resistance of pancreatic cancer to immune checkpoint inhibitors

Immunotherapy has become a new modality of cancer treatment, but has had a limited success in treating PDAC. A combination approach to immunotherapy, using both immune checkpoint inhibitors and immune activating agonists, is needed, as PDAC does not respond to single-agent checkpoint inhibitors. Studies have also supported using vaccine-based therapies to prime the tumor microenvironment of PDAC with effector T-cells. Other therapeutic strategies including epigenetic agents, stroma modulators, radiotherapy, and T-cell transfer therapies may also prime the tumor microenvironment to overcome resistance to immune checkpoint inhibitors.

Clinical Development of PD-1/PD-L1 Immunotherapy for Gastrointestinal Cancers: Facts and Hopes

Gastrointestinal (GI) cancers are among the most deadly malignancies. Although serial incremental survival benefits have been made with cytotoxic chemotherapy with metastatic disease, a plateau of achievement has been reached. Applying modern integrative genomic technology, distinct molecular subgroups have been identified in GI cancers. This not only highlighted the heterogeneity in tumors of each primary anatomical site but also identified novel therapeutic targets in distinct molecular subgroups and might improve the yield of clinical success. Molecular characteristics of tumors and their interaction with the tumor microenvironment would further affect development of combination therapy, including immunotherapy. Currently, immune checkpoint blockade attracts the most intense research, and the successful integration of these novel agents in GI cancers in the treatment paradigm requires an in-depth understanding of the diverse immune environment of these cancers. Clin Cancer Res; 23(20); 6002-11. ©2017 AACR.

An Immunosuppressive Dendritic Cell Subset Accumulates at Secondary Sites and Promotes Metastasis in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) after complete surgical resection is often followed by distant metastatic relapse for reasons that remain unclear. In this study, we investigated how the immune response at secondary sites affects tumor spread in murine models of metastatic PDAC. Early metastases were associated with dense networks of CD11b⁺CD11c⁺MHC-II⁺CD24⁺CD64^lowF4/80^low dendritic cells (DC), which developed from monocytes in response to tumor-released GM-CSF. These cells uniquely expressed MGL2 and PD-L2 in the metastatic microenvironment and preferentially induced the expansion of T regulatory cells (Treg) in vitro and in vivo Targeted depletion of this DC population in Mgl2^DTR hosts activated cytotoxic lymphocytes, reduced Tregs, and inhibited metastasis development. Moreover, blocking PD-L2 selectively activated CD8 T cells at secondary sites and suppressed metastasis, suggesting that the DCs use this particular pathway to inhibit CD8 T-cell-mediated tumor immunity. Phenotypically similar DCs accumulated at primary and secondary sites in other models and in human PDAC. These studies suggest that a discrete DC subset both expands Tregs and suppresses CD8 T cells to establish an immunosuppressive microenvironment conducive to metastasis formation. Therapeutic strategies to block the accumulation and immunosuppressive activity of such cells may help prevent PDAC progression and metastatic relapse after surgical resection. Cancer Res; 77(15); 4158-70. ©2017 AACR.

Immunotherapy in pancreatic cancer: Unleash its potential through novel combinations

Pancreatic cancer is the third leading cause of cancer mortality in both men and women in the United States, with poor response to current standard of care, short progression-free and overall survival. Immunotherapies that target cytotoxic T lymphocyte antigen-4, programmed cell death protein-1, and programmed death-ligand 1 checkpoints have shown remarkable activities in several cancers such as melanoma, renal cell carcinoma, and non-small cell lung cancer due to high numbers of somatic mutations, combined with cytotoxic T-cell responses. However, single checkpoint blockade was ineffective in pancreatic cancer, highlighting the challenges including the poor antigenicity, a dense desmoplastic stroma, and a largely immunosuppressive microenvironment. In this review, we will summarize available clinical results and ongoing efforts of combining immune checkpoint therapies with other treatment modalities such as chemotherapy, radiotherapy, and targeted therapy. These combination therapies hold promise in unleashing the potential of immunotherapy in pancreatic cancer to achieve better and more durable clinical responses by enhancing cytotoxic T-cell responses.

Gene Therapy for Pancreatic Cancer: Specificity, Issues and Hopes

A recent death projection has placed pancreatic ductal adenocarcinoma as the second cause of death by cancer in 2030. The prognosis for pancreatic cancer is very poor and there is a great need for new treatments that can change this poor outcome. Developments of therapeutic innovations in combination with conventional chemotherapy are needed urgently. Among innovative treatments the gene therapy offers a promising avenue. The present review gives an overview of the general strategy of gene therapy as well as the limitations and stakes of the different experimental in vivo models, expression vectors (synthetic and viral), molecular tools (interference RNA, genome editing) and therapeutic genes (tumor suppressor genes, antiangiogenic and pro-apoptotic genes, suicide genes). The latest developments in pancreatic carcinoma gene therapy are described including gene-based tumor cell sensitization to chemotherapy, vaccination and adoptive immunotherapy (chimeric antigen receptor T-cells strategy). Nowadays, there is a specific development of oncolytic virus therapies including oncolytic adenoviruses, herpes virus, parvovirus or reovirus. A summary of all published and on-going phase-1 trials is given. Most of them associate gene therapy and chemotherapy or radiochemotherapy. The first results are encouraging for most of the trials but remain to be confirmed in phase 2 trials.

Shifting paradigm of developing biologics for the treatment of pancreatic adenocarcinoma

Pancreatic adenocarcinoma is still widely considered as a deadly disease even though there are substantial therapeutic developments in the past decade. Using combinational chemotherapy regimens, represented by gemcitabine plus nab-paclitaxel and FOLFIRINOX, was able to improve overall survival in patients with advanced disease to a limited extent. It has been a challenge to develop targeted therapies that are focused on the neoplasm cells of pancreatic adenocarcinoma. Recently, targeting the stroma and immune compartments of pancreatic adenocarcinoma has shown promising results. The paradigm of biologics drug development therefore has been shifted by extending to these exciting areas. Although some of the preclinical and clinical researches in targeting the tumor microenvironment of pancreatic adenocarcinoma have shown promising results, others have resulted in controversial findings. Both comprehensive and in-depth researches on the basic science of the tumor microenvironment of pancreatic adenocarcinoma are thus warranted for the development of effective biologics that target the tumor microenvironment. Moreover, an ideal treatment for pancreatic adenocarcinoma shall be a combination of targeting both neoplastic cells and the tumor microenvironment.

Primary, Adaptive, and Acquired Resistance to Cancer Immunotherapy

Cancer immunotherapy can induce long lasting responses in patients with metastatic cancers of a wide range of histologies. Broadening the clinical applicability of these treatments requires an improved understanding of the mechanisms limiting cancer immunotherapy. The interactions between the immune system and cancer cells are continuous, dynamic, and evolving from the initial establishment of a cancer cell to the development of metastatic disease, which is dependent on immune evasion. As the molecular mechanisms of resistance to immunotherapy are elucidated, actionable strategies to prevent or treat them may be derived to improve clinical outcomes for patients.

PD-1 Blockade Promotes Emerging Checkpoint Inhibitors in Enhancing T Cell Responses to Allogeneic Dendritic Cells

Immune checkpoint inhibitors, which target coinhibitory T cell molecules to promote anticancer immune responses, are on the rise to become a new pillar of cancer therapy. However, current immune checkpoint-based therapies are successful only in a subset of patients and acquired resistances pose additional challenges. Finding new targets and combining checkpoint inhibitors might help to overcome these limitations. In this study, human T cells stimulated with allogeneic dendritic cells (DCs) were used to compare immune checkpoint inhibitors targeting TIM-3, BTLA, LAG-3, CTLA-4, and TIGIT alone or in combination with a PD-1 antibody. We found that PD-1 blockade bears a unique potency to enhance T cell proliferation and cytokine production. Other checkpoint inhibitors failed to significantly augment T cell responses when used alone. However, antibodies to TIM-3, BTLA, LAG-3, and CTLA-4 enhanced T cell proliferation in presence of a PD-1 antibody. Upregulation of coinhibitory T cell receptors upon PD-1 blockade was identified as a potential mechanism for synergistic effects between checkpoint inhibitors. Donor-specific variation in response to immune checkpoint inhibitors was attributed to the T cells rather than DCs. Additionally, we analyzed the regulation of checkpoint molecules and their ligands on T cells and allogeneic DCs in coculture, which suggested a PD-1 blockade-dependent crosstalk between T cells and APC. Our results indicate that several immune checkpoint inhibitors have the capacity to enhance T cell responses when combined with PD-1 blockade. Additional in vitro studies on human T cells will be useful to identify antibody combinations with the potential to augment T cell responses in cancer patients.

[Immunotherapy: Activation of a system not a pathway]

Immunotherapy is on the roll. After revolutionary effects in melanoma, immunotherapy is invading other locations. If current treatments, chemotherapies or targeted therapies block one pathway, immunotherapy should be understood as the activation of a whole system. Indeed, oncogenesis process is defined as an escape of the immune system and the stimulation of this system can block the carcinogenic process. The aim of the present review is to describe the place of immunotherapy in the treatment of solid cancers.

Twelve-year survival and immune correlates in dendritic cell-vaccinated melanoma patients

BACKGROUND

Reports on long-term (≥10 years) effects of cancer vaccines are missing. Therefore, in 2002, we initiated a phase I/II trial in cutaneous melanoma patients to further explore the immunogenicity of our DC vaccine and to establish its long-term toxicity and clinical benefit after a planned 10-year followup.

METHODS

Monocyte-derived DCs matured by TNFα, IL-1β, IL-6, and PGE2 and then loaded with 4 HLA class I and 6 class II-restricted tumor peptides were injected intradermally in high doses over 2 years. We performed serial immunomonitoring in all 53 evaluable patients.

RESULTS

Vaccine-specific immune responses including high-affinity, IFNγ-producing CD4+ and lytic polyfunctional CD8+ T cells were de novo induced or boosted in most patients. Exposure of mature DCs to trimeric soluble CD40 ligand, unexpectedly, did not further enhance such immune responses, while keyhole limpet hemocyanin (KLH) pulsing to provide unspecific CD4+ help promoted CD8+ T cell responses - notably, their longevity. An unexpected 19% of nonresectable metastatic melanoma patients are still alive after 11 years, a survival rate similar to that observed in ipilimumab-treated patients and achieved without any major (>grade 2) toxicity. Survival correlated significantly with the development of intense vaccine injection site reactions, and with blood eosinophilia after the first series of vaccinations, suggesting that prolonged survival was a consequence of DC vaccination.

CONCLUSIONS

Long-term survival in advanced melanoma patients undergoing DC vaccination is similar to ipilimumab-treated patients and occurs upon induction of tumor-specific T cells, blood eosinophilia, and strong vaccine injection site reactions occurring after the initial vaccinations.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00053391.

FUNDING

European Community, Sixth Framework Programme (Cancerimmunotherapy LSHC-CT-2006-518234; DC-THERA LSHB-CT-2004-512074), and German Research Foundation (CRC 643, C1, Z2).

Yes-associated protein mediates immune reprogramming in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a high degree of inflammation and profound immune suppression. Here we identify Yes-associated protein (Yap) as a critical regulator of the immunosuppressive microenvironment in both mouse and human PDAC. Within Kras:p53 mutant pancreatic ductal cells, Yap drives the expression and secretion of multiple cytokines/chemokines, which in turn promote the differentiation and accumulation of myeloid-derived suppressor cells (MDSCs) both in vitro and in vivo. Pancreas-specific knockout of Yap or antibody-mediated depletion of MDSCs promoted macrophage reprogramming, reactivation of T cells, apoptosis of Kras mutant neoplastic ductal cells and pancreatic regeneration after acute pancreatitis. In primary human PDAC, YAP expression levels strongly correlate with an MDSC gene signature, and high expression of YAP or MDSC-related genes predicts decreased survival in PDAC patients. These results reveal multifaceted roles of YAP in PDAC pathogenesis and underscore its promise as a therapeutic target for this deadly disease.

Surface engineering tumor cells with adjuvant-loaded particles for use as cancer vaccines

Cell surface engineering is an expanding field and whilst extensive research has been performed decorating cell surfaces with biomolecules, the engineering of cell surfaces with particles has been a largely unexploited area. This study reports on the assembly of cell-particle hybrids where irradiated tumor cells were surface engineered with adjuvant-loaded, biodegradable, biocompatible, polymeric particles, with the aim of generating a construct capable of functioning as a therapeutic cancer vaccine. Successfully assembled cell-particle hybrids presented here comprised either melanoma cells or prostate cancer cells stably adorned with Toll-like receptor-9 ligand-loaded particles using streptavidin-biotin cross-linking. Both cell-particle assemblies were tested in vivo for their potential as therapeutic cancer vaccines yielding promising therapeutic results for the prostate cancer model. The ramifications of results obtained for both tumor models are openly discussed.

Transformation of the tumour microenvironment by a CD40 agonist antibody correlates with improved responses to PD-L1 blockade in a mouse orthotopic pancreatic tumour model

Despite the availability of recently developed chemotherapy regimens, survival times for pancreatic cancer patients remain poor. These patients also respond poorly to immune checkpoint blockade therapies (anti-CTLA-4, anti-PD-L1, anti-PD-1), which suggests the presence of additional immunosuppressive mechanisms in the pancreatic tumour microenvironment (TME). CD40 agonist antibodies (αCD40) promote antigen presenting cell (APC) maturation and enhance macrophage tumouricidal activity, and may therefore alter the pancreatic TME to increase sensitivity to immune checkpoint blockade. Here, we test whether αCD40 transforms the TME in a mouse syngeneic orthotopic model of pancreatic cancer, to increase sensitivity to PD-L1 blockade. We found that whilst mice bearing orthotopic Pan02 tumours responded poorly to PD-L1 blockade, αCD40 improved overall survival. αCD40 transformed the TME, upregulating Th1 chemokines, increasing cytotoxic T cell infiltration and promoting formation of an immune cell-rich capsule separating the tumour from the normal pancreas. Furthermore, αCD40 drove systemic APC maturation, memory T cell expansion, and upregulated tumour and systemic PD-L1 expression. Combining αCD40 with PD-L1 blockade enhanced anti-tumour immunity and improved overall survival versus either monotherapy. These data provide further support for the potential of combining αCD40 with immune checkpoint blockade to promote anti-tumour immunity in pancreatic cancer.

Crosstalk between stromal cells and cancer cells in pancreatic cancer: New insights into stromal biology

Pancreatic cancer (PC) remains one of the most lethal malignancies worldwide. Increasing evidence has confirmed the pivotal role of stromal components in the regulation of carcinogenesis, invasion, metastasis, and therapeutic resistance in PC. Interaction between neoplastic cells and stromal cells builds a specific microenvironment, which further modulates the malignant properties of cancer cells. Instead of being a "passive bystander", stroma may play a role as a "partner in crime" in PC. However, the role of stromal components in PC is complex and requires further investigation. In this article, we review recent advances regarding the regulatory roles and mechanisms of stroma biology, especially the cellular components such as pancreatic stellate cells, macrophages, neutrophils, adipocytes, epithelial cells, pericytes, mast cells, and lymphocytes, in PC. Crosstalk between stromal cells and cancer cells is thoroughly investigated. We also review the prognostic value and molecular therapeutic targets of stroma in PC. This review may help us further understand the molecular mechanisms of stromal biology and its role in PC development and therapeutic resistance. Moreover, targeting stroma components may provide new therapeutic strategies for this stubborn disease.

Clinical Outcomes of Specific Immunotherapy in Advanced Pancreatic Cancer: A Systematic Review and Meta-Analysis

Specific immunotherapies, including vaccines with autologous tumor cells and tumor antigen-specific monoclonal antibodies, are important treatments for PC patients. To evaluate the clinical outcomes of PC-specific immunotherapy, we performed a systematic review and meta-analysis of the relevant published clinical trials. The effects of specific immunotherapy were compared with those of nonspecific immunotherapy and the meta-analysis was executed with results regarding the overall survival (OS), immune responses data, and serum cancer markers data. The pooled analysis was performed by using the random-effects model. We found that significantly improved OS was noted for PC patients utilizing specific immunotherapy and an improved immune response was also observed. In conclusion, specific immunotherapy was superior in prolonging the survival time and enhancing immunological responses in PC patients.

Immune-Related Adverse Effects of Cancer Immunotherapy- Implications for Rheumatology

Immune checkpoint inhibitors (ICIs) are increasingly studied and used as therapy for a growing number of malignancies. ICIs work by blocking inhibitory pathways of T-cell activation, leading to an immune response directed against tumors. Such nonspecific immunologic activation can lead to immune-related adverse events (IRAEs). Some IRAEs, including inflammatory arthritis, sicca syndrome, myositis, and vasculitis, are of special interest to rheumatologists. As use of ICIs increases, recognition of these IRAEs and developing treatment strategies will become important. In this review, the current literature on rheumatic and musculoskeletal IRAEs is summarized. The incidence, clinical presentations, and treatment considerations are highlighted.

Macropinocytosis of Nab-paclitaxel Drives Macrophage Activation in Pancreatic Cancer

Pancreatic cancer is a devastating disease that is largely refractory to currently available treatment strategies. Therapeutic resistance is partially attributed to the dense stromal reaction of pancreatic ductal adenocarcinoma tumors that includes a pervasive infiltration of immunosuppressive (M2) macrophages. Nab-paclitaxel (trade name Abraxane) is a nanoparticle albumin-bound formulation of paclitaxel that, in combination with gemcitabine, is currently the first-line treatment for pancreatic cancer. Here, we show that macrophages internalized nab-paclitaxel via macropinocytosis. The macropinocytic uptake of nab-paclitaxel induced macrophage immunostimulatory (M1) cytokine expression and synergized with IFNγ to promote inducible nitric oxide synthase expression in a TLR4-dependent manner. Nab-paclitaxel was internalized by tumor-associated macrophages in vivo, and therapeutic doses of nab-paclitaxel alone, and in combination with gemcitabine, increased the MHCII⁺CD80⁺CD86⁺ M1 macrophage population. These data revealed an unanticipated role for nab-paclitaxel in macrophage activation and rationalized its potential use to target immune evasion in pancreatic cancer. Cancer Immunol Res; 5(3); 182-90. ©2017 AACR.

Targeted Therapies Combined With Immune Checkpoint Therapy

The age of personalized medicine continues to evolve within clinical oncology with the arsenal available to clinicians in a variety of malignancies expanding at an exponential rate. The development and advancement of molecular treatment modalities, including targeted therapy and immune checkpoint blockade, continue to flourish. Treatment with targeted therapy (BRAF, MEK, and other small molecule inhibitors) can be associated with swift disease control and high response rates, but limited durability when used as monotherapy. Conversely, treatment with immune checkpoint blockade monotherapy regimens (anti-cytotoxic T-lymphocyte antigen 4 and anti-programmed cell death protein 1/programmed cell death protein 1 ligand) tends to have lower response rates than that observed with BRAF-targeted therapy, although these treatments may offer long-term durable disease control. With the advent of these forms of therapy, there was interest early on in empirically combining targeted therapy with immune checkpoint blockade with the hopes of preserving high response rates and adding durability; however, there is now strong scientific rationale for combining these forms of therapy-and early evidence of synergy in preclinical models of melanoma. Clinical trials combining these strategies are ongoing, and mature data regarding response rates and durability are not yet available. Synergy may ultimately be apparent; however, it has also become clear that complexities exist regarding toxicity when combining these therapies. Nonetheless, this increased appreciation of the complex interplay between oncogenic mutations and antitumor immunity has opened up tremendous opportunities for studying targeted agents and immunotherapy in combination, which extends far beyond melanoma to other solid tumors and also to hematologic malignancies.