Breakthrough of the year 2013. Cancer immunotherapy

The place of targeted agents in the treatment of elderly patients with metastatic colorectal cancer

Despite the high prevalence of colorectal cancer in a continuously aging population and the substantial advances in the treatment of metastatic disease during the past decade, the treatment of elderly patients with advanced, unresectable or metastatic colorectal cancer is a clearly unmet need. Since older patients are under-represented or even excluded from randomized trials, the evidence that oncologists use as guidance is weak. However, small prospective studies, pooled analyses and observational studies show that combination approaches are safe, efficacious and feasible in the geriatric population with metastatic colorectal cancer. The use of biologic agents targeting angiogenesis and the epidermal growth factor receptor, which have been shown to clearly improve outcomes in multiple prospective trials in patients with advanced colorectal cancer, is a vital component of the aforementioned combination approaches. Herein, we review all available data concerning the management of elderly patients with these agents and underscore the differences between this age subgroup and younger patients.

Beyond CTLA-4: novel immunotherapy strategies for metastatic melanoma

The treatment of metastatic melanoma is rapidly evolving. The discovery of BRAF and MEK inhibitors was an important milestone. Unfortunately, although response rates are high, disease progression is universal. Despite the success of IL-2 and adjuvant IFL-α2b, these two agents remained the only approved immunotherapy approaches. In recent years, the use of immunotherapy has drawn attention with the recognition of the mechanisms of tumor immune evasion. Blockade of these mechanisms may improve outcomes. However, the potential adverse events, the optimal use of these modalities, the high cost and the absence of predictive markers remain unmet challenges. Herein, we review the immunotherapy strategies in melanoma, either approved or under evaluation, and present the relevant data concerning their efficacy and safety.

The bitter side of sweet: the role of Galectin-9 in immunopathogenesis of viral infections

In recent years, a critical role for β-galactoside-binding protein, Galectin-9 (Gal-9) has emerged in infectious disease, autoimmunity, and cancer. It is a ligand for T cell immunoglobulin mucin domain 3 (Tim-3), a type-I glycoprotein that is persistently expressed on dysfunctional T cells during chronic viral infections. Gal-9 exerts its pivotal immunomodulatory effects by inducing apoptosis or suppressing effector functions via engagement with its receptor, Tim-3. Recent studies report elevation of circulating Gal-9 in humans infected with different viral infections. Interaction of soluble Gal-9 with Tim-3 expressed on the surface of activated CD4+ T cells renders them less susceptible to HIV-1 infection, while enhanced HIV infection occurs when Gal-9 interacts with a different receptor than Tim-3. This indicates the versatile role of Gal-9 in viral pathogenesis. For instance, higher expression of Tim-3 during chronic viral infection and elevation of plasma Gal-9 may have evolved to limit persistent immune activation and pathogenic T cells activity. In contrast, Gal-9 can suppress the effectiveness of immunity against viral infections. In agreement, Gal-9 knockout mice mount a more robust and vigorous virus-specific immune response in acute and chronic viral infections resulting in rapid viral clearance. In line with this observation, blocking Gal-9 signals to Tim-3-expressing T cells result in improved immune responses. Here we review the biological and immunological properties of Gal-9 in viral infections (HIV, HCV, HBV, HSV, CMV, influenza, and dengue virus). Manipulating Gal-9 signals may have immunotherapeutic potential and could represent an alternative approach for improving immune responses to viral infections/vaccines.

Meeting report from the second EurocanPlatform summer school on translational cancer research, Portugal, 20-24 October 2014

The second EurocanPlatform summer school was held in Algarve, Portugal and attracted scientists, clinicians and pathologists with a common interest in cancer research to discuss the latest developments and challenges in the field. The meeting focused on translational cancer research and also included lectures, workshops and discussions, which covered all aspects of the translational research continuum, from early detection through treatment to survivorship. The rate of new cancer cases and cancer mortality increases every year. Although the last decade witnessed enormous progress in understanding cancer biology and the development of new therapies, the efficacy of these therapies is challenged by cancer resistance. It clearly suggests that new druggable targets are required and their translation from laboratory to bedside must be faster and more efficient to improve survival rates and standards of care.

Optical in vivo imaging of the alarmin S100A9 in tumor lesions allows for estimation of the individual malignant potential by evaluation of tumor-host cell interaction

Tumors recruit and reprogram immune cells to support tumor development and spread, the most prominent among them being of monocytic origin such as tumor-associated macrophages (TAM) or myeloid-derived suppressor cells (MDSC). The alarmin S100A8/A9 has been implicated in the induction of TAM and MDSC. We assessed S100A9 as a molecular imaging marker for the activity of tumor-associated immune cells in a syngeneic murine breast cancer model. S100A9 could serve as a surrogate marker for tumor immune crosstalk as a function of malignancy, providing a tool with the potential for both basic research in tumor immunology and clinical stratification of patients.

METHODS

BALB/c mice were inoculated with murine breast cancer cells of common origin but different metastatic capability. At different times during tumor development, optical imaging was performed using a S100A9-specific probe to visualize activated monocytes. To further explore the impact of tumor-educated monocytes, splenic myeloid cells were isolated from either healthy or tumor-bearing animals and injected into tumor-bearing mice. We analyzed the effect of the cell transfer on immune cell activity and tumor development.

RESULTS

We could prove S100A9-driven imaging to sensitively and specifically reflect monocyte activity in primary tumor lesions. The imaging results were corroborated by histology and fluorescence-activated cell sorting analyses. In a prospective experiment, S100A9 imaging proved indicative of the individual tumor growth, with excellent correlation. Moreover, we could show that the monocyte activity as depicted by S100A9 activity in the primary tumor lesion mirrored the tumor's metastatic behavior. Treatment with tumor-primed splenic monocytes induced increased tumor growth, accompanied by an augmented infiltration of activated myeloid cells (MDSC and TAM) into the tumor. The consecutive S100A9 expression as depicted by in vivo imaging was significantly increased.

CONCLUSION

S100A9 proved to be a sensitive and specific marker for the activity of tumor-associated immune cells. To our knowledge, S100A9 imaging represents a first in vivo imaging approach for the estimation of recruitment and activity of tumor-associated myeloid immune cells. We demonstrated the potential value of this imaging approach for prediction of local and systemic tumor development.

MICA SNPs and the NKG2D system in virus-induced HCC

Hepatocellular carcinoma (HCC) is one of the most frequent causes of cancer-related death globally. Above well-known risk factors for HCC development ranging from various toxins to diseases such as diabetes mellitus, chronic infection with hepatitis B virus and hepatitis C virus (HCV) poses the most serious threat, constituting the cause in more than 80 % of cases. In addition to the viral genes intensively investigated, the pathophysiological importance of host genetic factors has also been greatly and increasingly appreciated. Genome-wide association studies (GWAS) comprehensively search the host genome at the single-nucleotide level, and have successfully identified the genomic region associated with a whole variety of diseases. With respect to HCC, there have been reports from several groups on single nucleotide polymorphisms (SNPs) associated with hepatocarcinogenesis, among which was our GWAS discovering MHC class I polypeptide-related sequence A (MICA) as a susceptibility gene for HCV-induced HCC. MICA is a natural killer (NK) group 2D (NKG2D) ligand, whose interaction with NKG2D triggers NK cell-mediated cytotoxicity toward the target cells, and is a key molecule in tumor immune surveillance as its expression is induced on stressed cells such as transformed tumor cells for the detection by NK cells. In this review, the latest understanding of the MICA-NKG2D system in viral HCC, particularly focused on its antitumor properties and the involvement of MICA SNPs, is summarized, followed by a discussion of targets for state-of-the-art cancer immunotherapy with personalized medicine in view.

Sequencing the functional antibody repertoire--diagnostic and therapeutic discovery

The development of high-throughput DNA sequencing technologies has enabled large-scale characterization of functional antibody repertoires, a new method of understanding protective and pathogenic immune responses. Important parameters to consider when sequencing antibody repertoires include the methodology, the B-cell population and clinical characteristics of the individuals analysed, and the bioinformatic analysis. Although focused sequencing of immunoglobulin heavy chains or complement determining regions can be utilized to monitor particular immune responses and B-cell malignancies, high-fidelity analysis of the full-length paired heavy and light chains expressed by individual B cells is critical for characterizing functional antibody repertoires. Bioinformatic identification of clonal antibody families and recombinant expression of representative members produces recombinant antibodies that can be used to identify the antigen targets of functional immune responses and to investigate the mechanisms of their protective or pathogenic functions. Integrated analysis of coexpressed functional genes provides the potential to further pinpoint the most important antibodies and clonal families generated during an immune response. Sequencing antibody repertoires is transforming our understanding of immune responses to autoimmunity, vaccination, infection and cancer. We anticipate that antibody repertoire sequencing will provide next-generation biomarkers, diagnostic tools and therapeutic antibodies for a spectrum of diseases, including rheumatic diseases.

CRISPR-Cas9: a new and promising player in gene therapy

First introduced into mammalian organisms in 2013, the RNA-guided genome editing tool CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease 9) offers several advantages over conventional ones, such as simple-to-design, easy-to-use and multiplexing (capable of editing multiple genes simultaneously). Consequently, it has become a cost-effective and convenient tool for various genome editing purposes including gene therapy studies. In cell lines or animal models, CRISPR-Cas9 can be applied for therapeutic purposes in several ways. It can correct the causal mutations in monogenic disorders and thus rescue the disease phenotypes, which currently represents the most translatable field in CRISPR-Cas9-mediated gene therapy. CRISPR-Cas9 can also engineer pathogen genome such as HIV for therapeutic purposes, or induce protective or therapeutic mutations in host tissues. Moreover, CRISPR-Cas9 has shown potentials in cancer gene therapy such as deactivating oncogenic virus and inducing oncosuppressor expressions. Herein, we review the research on CRISPR-mediated gene therapy, discuss its advantages, limitations and possible solutions, and propose directions for future research, with an emphasis on the opportunities and challenges of CRISPR-Cas9 in cancer gene therapy.

Redirection of genetically engineered CAR-T cells using bifunctional small molecules

Chimeric antigen receptor (CAR)-engineered T cells (CAR-Ts) provide a potent antitumor response and have become a promising treatment option for cancer. However, despite their efficacy, CAR-T cells are associated with significant safety challenges related to the inability to control their activation and expansion and terminate their response. Herein, we demonstrate that a bifunctional small molecule "switch" consisting of folate conjugated to fluorescein isothiocyanate (folate-FITC) can redirect and regulate FITC-specific CAR-T cell activity toward folate receptor (FR)-overexpressing tumor cells. This system was shown to be highly cytotoxic to FR-positive cells with no activity against FR-negative cells, demonstrating the specificity of redirection by folate-FITC. Anti-FITC-CAR-T cell activation and proliferation was strictly dependent on the presence of both folate-FITC and FR-positive cells and was dose titratable with folate-FITC switch. This novel treatment paradigm may ultimately lead to increased safety for CAR-T cell immunotherapy.

Robust Antitumor Effects of Combined Anti-CD4-Depleting Antibody and Anti-PD-1/PD-L1 Immune Checkpoint Antibody Treatment in Mice

Depletion of CD4(+) cells in tumor-bearing mice has strong antitumor effects. However, the mechanisms underlying these effects and the therapeutic benefits of CD4(+) cell depletion relative to other immunotherapies have not been fully evaluated. Here, we investigated the antitumor effects of an anti-CD4-depleting mAb as a monotherapy or in combination with immune checkpoint mAbs. In B16F10, Colon 26, or Lewis lung carcinoma subcutaneous tumor models, administration of the anti-CD4 mAb alone had strong antitumor effects that were superior to those elicited by CD25(+) Treg depletion or other immune checkpoint mAbs, and which were completely reversed by CD8(+) cell depletion. CD4(+) cell depletion led to the proliferation of tumor-specific CD8(+) T cells in the draining lymph node and increased infiltration of PD-1(+)CD8(+) T cells into the tumor, with a shift toward type I immunity within the tumor. Combination treatment with the anti-CD4 mAb and immune checkpoint mAbs, particularly anti-PD-1 or anti-PD-L1 mAbs, synergistically suppressed tumor growth and greatly prolonged survival. To our knowledge, this work represents the first report of robust synergy between anti-CD4 and anti-PD-1 or anti-PD-L1 mAb therapies.

Rational development and characterization of humanized anti-EGFR variant III chimeric antigen receptor T cells for glioblastoma

Chimeric antigen receptors (CARs) are synthetic molecules designed to redirect T cells to specific antigens. CAR-modified T cells can mediate long-term durable remissions in B cell malignancies, but expanding this platform to solid tumors requires the discovery of surface targets with limited expression in normal tissues. The variant III mutation of the epidermal growth factor receptor (EGFRvIII) results from an in-frame deletion of a portion of the extracellular domain, creating a neoepitope. We chose a vector backbone encoding a second-generation CAR based on efficacy of a murine scFv-based CAR in a xenograft model of glioblastoma. Next, we generated a panel of humanized scFvs and tested their specificity and function as soluble proteins and in the form of CAR-transduced T cells; a low-affinity scFv was selected on the basis of its specificity for EGFRvIII over wild-type EGFR. The lead candidate scFv was tested in vitro for its ability to direct CAR-transduced T cells to specifically lyse, proliferate, and secrete cytokines in response to antigen-bearing targets. We further evaluated the specificity of the lead CAR candidate in vitro against EGFR-expressing keratinocytes and in vivo in a model of mice grafted with normal human skin. EGFRvIII-directed CAR T cells were also able to control tumor growth in xenogeneic subcutaneous and orthotopic models of human EGFRvIII(+) glioblastoma. On the basis of these results, we have designed a phase 1 clinical study of CAR T cells transduced with humanized scFv directed to EGFRvIII in patients with either residual or recurrent glioblastoma (NCT02209376).

Radiation meets immunotherapy - a perfect match in the era of combination therapy?

PURPOSE

This review focuses on recent advances in the field of combining radiation with immunotherapy for the treatment of malignant diseases, since various combinatorial cancer therapy approaches have lately proven highly successful.

RESULTS

With initial case reports and anecdotes progressively converting into solid clinical data, interest in cancer immunotherapy (CIT) has risen steeply. Especially immune checkpoint blockade therapies have recently celebrated tremendous successes in the treatment of severe malignancies resistant to conventional treatment strategies. Nevertheless, the high variability of patient responses to CIT remains a major hurdle, clearly indicating an urgent need for improvement. It has been suggested that successful cancer therapy most probably involves combinatorial treatment approaches. Radiotherapy (RT) has been proposed as a powerful partner for CIT due to its broad spectrum of immune modulatory characteristics. Several preclinical studies, supported by an increasing number of clinical observations, have demonstrated synergistic interactions between RT and CIT resulting in significantly improved therapy outcomes.

CONCLUSIONS

Numerous reports have shown that radiation is capable of tipping the scales from tumor immune evasion to elimination in different tumor types. The next puzzle to be solved is the question of logistics - including types, schedule and dosage of combinatorial RT and CIT strategies.

Targeting the tumor microenvironment to enhance antitumor immune responses

The identification of tumor-specific antigens and the immune responses directed against them has instigated the development of therapies to enhance antitumor immune responses. Most of these cancer immunotherapies are administered systemically rather than directly to tumors. Nonetheless, numerous studies have demonstrated that intratumoral therapy is an attractive approach, both for immunization and immunomodulation purposes. Injection, recruitment and/or activation of antigen-presenting cells in the tumor nest have been extensively studied as strategies to cross-prime immune responses. Moreover, delivery of stimulatory cytokines, blockade of inhibitory cytokines and immune checkpoint blockade have been explored to restore immunological fitness at the tumor site. These tumor-targeted therapies have the potential to induce systemic immunity without the toxicity that is often associated with systemic treatments. We review the most promising intratumoral immunotherapies, how these affect systemic antitumor immunity such that disseminated tumor cells are eliminated, and which approaches have been proven successful in animal models and patients.

Regulatory T cells are not a strong predictor of survival for patients with glioblastoma

BACKGROUND

Regulatory T cells (Tregs) are potentially prognostic indicators in patients with glioblastoma. If differences in frequency of Tregs in tumor or blood account for substantial variation in patient survival, then reliably measuring Tregs may enhance treatment selection and improve outcomes.

METHODS

We measured Tregs and CD3+ T cells in tumors and blood from 25 patients with newly diagnosed glioblastoma. Tumor-infiltrating Tregs and CD3+ T cells, measured by quantitative DNA demethylation analysis (epigenetic qPCR) and by immunohistochemistry, and peripheral blood Treg proportions measured by flow cytometry were correlated with patient survival. Additionally, we analyzed data from The Cancer Genome Atlas (TCGA) to correlate the expression of Treg markers with patient survival and glioblastoma subtypes.

RESULTS

Tregs, as measured in tumor tissue and peripheral blood, did not correlate with patient survival. Although there was a correlation between tumor-infiltrating Tregs expression by epigenetic qPCR and immunohistochemistry, epigenetic qPCR was more sensitive and specific. Using data from TCGA, mRNA expression of Forkhead box protein 3 (FoxP3) and Helios and FoxP3 methylation level did not predict survival. While the classical glioblastoma subtype corresponded to lower expression of Treg markers, these markers did not predict survival in any of the glioblastoma subtypes.

CONCLUSIONS

Although immunosuppression is a hallmark of glioblastoma, Tregs as measured in tissue by gene expression, immunohistochemistry, or demethylation and Tregs in peripheral blood measured by flow cytometry do not predict survival of patients. Quantitative DNA demethylation analysis provides an objective, sensitive, and specific way of identifying Tregs and CD3+ T cells in glioblastoma.

Targeted localized use of therapeutic antibodies: a review of non-systemic, topical and oral applications

Therapeutic antibodies provide important tools in the "medicine chest" of today's clinician for the treatment of a range of disorders. Typically monoclonal or polyclonal antibodies are administered in large doses, either directly or indirectly into the circulation, via a systemic route which is well suited for disseminated ailments. Diseases confined within a specific localized tissue, however, may be treated more effectively and at reduced cost by a delivery system which targets directly the affected area. To explore the advantages of the local administration of antibodies, we reviewed current alternative, non-systemic delivery approaches which are in clinical use, being trialed or developed. These less conventional approaches comprise: (a) local injections, (b) topical and (c) peroral administration routes. Local delivery includes intra-ocular injections into the vitreal humor (i.e. Ranibizumab for age-related macular degeneration), subconjunctival injections (e.g. Bevacizumab for corneal neovascularization), intra-articular joint injections (i.e. anti-TNF alpha antibody for persistent inflammatory monoarthritis) and intratumoral or peritumoral injections (e.g. Ipilimumab for cancer). A range of other strategies, such as the local use of antibacterial antibodies, are also presented. Local injections of antibodies utilize doses which range from 1/10th to 1/100th of the required systemic dose therefore reducing both side-effects and treatment costs. In addition, any therapeutic antibody escaping from the local site of disease into the systemic circulation is immediately diluted within the large blood volume, further lowering the potential for unwanted effects. Needle-free topical application routes become an option when the condition is restricted locally to an external surface. The topical route may potentially be utilized in the form of eye drops for infections or corneal neovascularization or be applied to diseased skin for psoriasis, dermatitis, pyoderma gangrenosum, antibiotic resistant bacterial infections or ulcerated wounds. Diseases confined to the gastrointestinal tract can be targeted directly by applying antibody via the injection-free peroral route. The gastrointestinal tract is unusual in that its natural immuno-tolerant nature ensures the long-term safety of repeatedly ingesting heterologous antiserum or antibody materials. Without the stringent regulatory, purity and clean room requirements of manufacturing parenteral (injectable) antibodies, production costs are minimal, with the potential for more direct low-cost targeting of gastrointestinal diseases, especially with those caused by problematic antibiotic resistant or toxigenic bacteria (e.g. Clostridium difficile, Helicobacter pylori), viruses (e.g. rotavirus, norovirus) or inflammatory bowel disease (e.g. ulcerative colitis, Crohn's disease). Use of the oral route has previously been hindered by excessive antibody digestion within the gastrointestinal tract; however, this limitation may be overcome by intelligently applying one or more strategies (i.e. decoy proteins, masking therapeutic antibody cleavage sites, pH modulation, enzyme inhibition or encapsulation). These aspects are additionally discussed in this review and novel insights also provided. With the development of new applications via local injections, topical and peroral routes, it is envisaged that an extended range of ailments will increasingly fall within the clinical scope of therapeutic antibodies further expanding this market.

Mechanisms of and strategies for overcoming resistance to anti-vascular endothelial growth factor therapy in non-small cell lung cancer

Sustained angiogenesis is a hallmark of cancer. Because of the primary role of vascular endothelial growth factors (VEGFs) and their receptors in angiogenesis, VEGF-targeted agents have been developed to inhibit these signaling processes in non-small cell lung cancer (NSCLC). However, the clinical benefits are transient and resistance often rapidly develops. Insights into the molecular mechanisms of resistance would help to develop novel strategies to improve the efficacy of antiangiogenic therapies. This review discusses the mechanisms of resistance to anti-VEGF therapy and the postulated strategies to optimize antiangiogenic therapy. A number of multitargeted tyrosine kinase inhibitors currently in phase III clinical development for NSCLC are summarized. The emerging combination of antiangiogenic therapy with tumor immunotherapy is also discussed.

Current and Future Approaches in the Management of Non-Small-Cell Lung Cancer Patients With Resistance to EGFR TKIs

Metastatic non-small-cell lung cancer carries a dismal prognosis. However, the recognition of the predictive value of activating epidermal growth factor receptor (EGFR) mutations and the availability of tyrosine kinase inhibitors has markedly improved the prognosis of these patients, because treatment with these inhibitors induces rapid and robust responses. Unfortunately, the responses are not durable and resistance inevitably occurs after a median of 9 to 14 months. Although the management of resistant patients who harbor EGFR mutations is rapidly evolving, there are no conclusive guidelines regarding this issue. However, palliative cytotoxic chemotherapy is considered the standard of care for these patients. The elucidation of the mechanisms of acquired resistance has led to efforts to personalize the treatment approach. Promising results from early clinical trials using the third-generation inhibitors that specifically target the most common mechanism of resistance, the gatekeeper T790M mutation, provide the basis to look to the future with cautious optimism. Moreover, it has been shown that in some cases of oligoprogressive disease, aggressively treating all metastatic sites while continuing the targeted treatment could improve outcomes. Herein, we review the treatment strategies being evaluated that will shape the future management of these patients.

Standing on the shoulders of giants: a scientific journey from Singapore to stem cells

Cellular therapy was introduced in the early 1980s as adoptive immunotherapy for cancer and has now expanded to stem cell treatment for a wide variety of indications. During the same period, the concept of the fetus as a patient evolved from fantasy to everyday reality. The intersection of these two fields offers great potential for cures in childhood diseases. The fetal treatment of spina bifida is one such disease. Global surgery has also emerged as a cost effective approach to reducing the worldwide burden of childhood disease.

The New Era of Cancer Immunotherapy: Manipulating T-Cell Activity to Overcome Malignancy

Using the immune system to control cancer has been investigated for over a century. Yet it is only over the last several years that therapeutic agents acting directly on the immune system have demonstrated improved overall survival for cancer patients in phase III clinical trials. Furthermore, it appears that some patients treated with such agents have been cured of metastatic cancer. This has led to increased interest and acceleration in the rate of progress in cancer immunotherapy. Most of the current immunotherapeutic success in cancer treatment is based on the use of immune-modulating antibodies targeting critical checkpoints (CTLA-4 and PD-1/PD-L1). Several other immune-modulating molecules targeting inhibitory or stimulatory pathways are being developed. The combined use of these medicines is the subject of intense investigation and holds important promise. Combination regimens include those that incorporate targeted therapies that act on growth signaling pathways, as well as standard chemotherapy and radiation therapy. In fact, these standard therapies have intrinsic immune-modulating properties that can support antitumor immunity. In the years ahead, adoptive T-cell therapy will also be an important part of treatment for some cancer patients. Other areas which are regaining interest are the use of oncolytic viruses that immunize patients against their own tumors and the use of vaccines against tumor antigens. Immunotherapy has demonstrated unprecedented durability in controlling multiple types of cancer and we expect its use to continue expanding rapidly.

Intradermal vaccination using the novel microneedle device MicronJet600: Past, present, and future

Intradermal immunization has become a forefront of vaccine improvement, both scientifically and commercially. Newer technologies are being developed to address the need to reduce the dose required for vaccination and to improve the reliability and ease of injection, which have been major hurdles in expanding the number of approved vaccines using this route of administration. In this review, 7 y of clinical experience with a novel intradermal delivery device, the MicronJet600, which is a registered hollow microneedle that simplifies the delivery of liquid vaccines, are summarized. This device has demonstrated both significant dose-sparing and superior immunogenicity in various vaccine categories, as well as in diverse subject populations and age groups. These studies have shown that intradermal delivery using this device is safe, effective, and preferred by the subjects. Comparison with other intradermal devices and potential new applications for intradermal delivery that could be pursued in the future are also discussed.

Classification of current anticancer immunotherapies

During the past decades, anticancer immunotherapy has evolved from a promising therapeutic option to a robust clinical reality. Many immunotherapeutic regimens are now approved by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, and many others are being investigated as standalone therapeutic interventions or combined with conventional treatments in clinical studies. Immunotherapies may be subdivided into "passive" and "active" based on their ability to engage the host immune system against cancer. Since the anticancer activity of most passive immunotherapeutics (including tumor-targeting monoclonal antibodies) also relies on the host immune system, this classification does not properly reflect the complexity of the drug-host-tumor interaction. Alternatively, anticancer immunotherapeutics can be classified according to their antigen specificity. While some immunotherapies specifically target one (or a few) defined tumor-associated antigen(s), others operate in a relatively non-specific manner and boost natural or therapy-elicited anticancer immune responses of unknown and often broad specificity. Here, we propose a critical, integrated classification of anticancer immunotherapies and discuss the clinical relevance of these approaches.

HLA ligandome analysis identifies the underlying specificities of spontaneous antileukemia immune responses in chronic lymphocytic leukemia (CLL)

The breakthrough development of clinically effective immune checkpoint inhibitors illustrates the potential of T-cell-based immunotherapy to effectively treat malignancies. A remaining challenge is to increase and guide the specificities of anticancer immune responses, e.g., by therapeutic vaccination or by adoptive T-cell transfer. By analyzing the landscape of naturally presented HLA class I and II ligands of primary chronic lymphocytic leukemia (CLL), we delineated a novel category of tumor-associated T-cell antigens based on their exclusive and frequent representation in the HLA ligandome of leukemic cells. These antigens were validated across different stages and mutational subtypes of CLL and found to be robustly represented in HLA ligandomes of patients undergoing standard chemo-/immunotherapy. We demonstrate specific immune recognition of these antigens exclusively in CLL patients, with the frequencies of representation in CLL ligandomes correlating with the frequencies of immune recognition by patient T cells. Moreover, retrospective survival analysis revealed survival benefits for patients displaying immune responses to these antigens. These results directly imply these nonmutant self-peptides as pathophysiologically relevant tumor antigens and encourages their implementation for cancer immunotherapy.

CC motif chemokine ligand 19 suppressed colorectal cancer in vivo accompanied by an increase in IL-12 and IFN-γ

In this study we investigate the role of CC motif chemokine ligand 19 (CCL19) to colorectal cancer (CRC) in vivo. We injected different dose of recombinant mouse CCL19 (rmCCL19) in the tumor site of the model of transplanted tumor. Result shows that rmCCL19 can suppress CRC tumorigenesis and growth in vivo, and it can also prolong overall survival of mice. Quantitative reverse transcription-polymerase chain reaction and enzyme linked immunosorbent assay results showed that the interferon-γ (IFN-γ) and interleukin-12 (IL-12) levels in the tumors and plasma were significantly enhanced after processing with rmCCL19.

Stereotactic Radiation Therapy Augments Antigen-Specific PD-1-Mediated Antitumor Immune Responses via Cross-Presentation of Tumor Antigen

The immune-modulating effects of radiotherapy (XRT) have gained considerable interest recently, and there have been multiple reports of synergy between XRT and immunotherapy. However, additional preclinical studies are needed to demonstrate the antigen-specific nature of radiation-induced immune responses and elucidate potential mechanisms of synergy with immunotherapy. Here, we demonstrate the ability of stereotactic XRT to induce endogenous antigen-specific immune responses when it is combined with anti-PD-1 checkpoint blockade immunotherapy. Using the small animal radiation research platform (SARRP), image-guided stereotactic XRT delivered to B16-OVA melanoma or 4T1-HA breast carcinoma tumors resulted in the development of antigen-specific T cell- and B cell-mediated immune responses. These immune-stimulating effects of XRT were significantly increased when XRT was combined with either anti-PD-1 therapy or regulatory T cell (Treg) depletion, resulting in improved local tumor control. Phenotypic analyses of antigen-specific CD8 T cells revealed that XRT increased the percentage of antigen-experienced T cells and effector memory T cells. Mechanistically, we found that XRT upregulates tumor-associated antigen-MHC complexes, enhances antigen cross-presentation in the draining lymph node, and increases T-cell infiltration into tumors. These findings demonstrate the ability of XRT to prime an endogenous antigen-specific immune response and provide an additional mechanistic rationale for combining radiation with PD-1 blockade in the clinic.

Preclinical screening for acute toxicity of therapeutic monoclonal antibodies in a hu-SCID model

Monoclonal antibodies (mAbs) have been a spectacular clinical and commercial success in the treatment of cancer and autoimmune diseases. Many of these mAbs (for example, OKT3, Campath-1H, rituximab and infliximab) are against surface or secreted products of lymphocytes. However, mAbs can have a variety of adverse effects including fever, chills and nausea. This is probably a result of cytokine release, which is most seriously manifested as a ‘cytokine storm' as highlighted by the TGN1412 (anti-CD28) trial. Prediction of adverse effects of mAbs would be clinically advantageous and numerous in vitro assays attempting to predict adverse effects have been reported. Here, we report an in vivo humanized mouse model to detect adverse effects in response to OKT3, Campath-1H or the polyclonal Ab preparation anti-thymocyte globulin. We found that the administration of each of these Abs to humanized mice led to acute clinical symptoms such as piloerection, hypomotility and hypothermia, particularly when delivered via the intravenous route. A cytokine storm occurred in the humanized mice receiving OKT3. This model system is a potentially useful tool to predict adverse effects and select initial doses for first-in-human trials. We would advocate this in vivo model, in addition to current in vitro preclinical testing, as a more representative and robust means of assessing potential adverse effects of mAb before their human use.

STING, nanoparticles, autoimmune disease and cancer: a novel paradigm for immunotherapy?

DNA has potent immunogenic properties that are useful to enhance vaccine efficacy. DNA also incites hyperinflammation and autoimmunity if DNA sensing is not regulated. Paradoxically, DNA regulates immunity and autoimmunity when administered systemically as DNA nanoparticles. DNA nanoparticles regulated immunity via cytosolic DNA sensors that activate the signaling adaptor stimulator of interferon genes. In this review, we describe how DNA sensing to activate stimulator of interferon genes promotes regulatory responses and discuss the biological and clinical implications of these responses for understanding disease progression and designing better therapies for patients with chronic inflammatory diseases, such as autoimmune syndromes or cancer.

Development of T cells redirected to glypican-3 for the treatment of hepatocellular carcinoma

PURPOSE

The aim of our study is to elucidate whether T cells expressing GPC3-targeted chimeric antigen receptor (CAR) can efficiently eliminate GPC3-positive HCC cells and their potential in the treatment of HCC.

EXPERIMENTAL DESIGN

T cells expressing a first-generation and third-generation GPC3-targeted CAR were prepared using lentiviral vector transduction. The in vitro and in vivo cytotoxic activities of the genetically engineered CAR T cells were evaluated against various HCC cell lines.

RESULTS

GPC3-targeted CAR T cells could efficiently kill GPC3-positive HCC cells but not GPC3-negative cells in vitro. These cytotoxic activities seemed to be positively correlated with GPC3 expression levels in the target cells. In addition, T cells expressing the third-generation GPC3-targeted CAR could eradicate HCC xenografts with high level of GPC3 expression and efficiently suppress the growth of HCC xenografts with low GPC3 expression level in vivo. The survival of the mice bearing established orthotopic Huh-7 xenografts was significantly prolonged by the treatment with the third-generation GPC3-targeted CAR T cells.

CONCLUSIONS

GPC3-targeted CAR T cells could potently eliminate GPC3-positive HCC cells, thereby providing a promising therapeutic intervention for GPC3-positive HCC.

STAT1-S727 - the license to kill

Serine phosphorylation has generally been considered indispensable for full transcriptional activity of STAT proteins. Recent data indicate that CDK8-mediated phosphorylation of signal transducer and activator of transcription 1 (STAT1) on S727 inhibits natural killer (NK) cell cytotoxicity and restrains tumor surveillance. These findings implicate CDK8 as a promising target for immunotherapy.

Tumor-induced myeloid dysfunction and its implications for cancer immunotherapy

Immune function relies on an appropriate balance of the lymphoid and myeloid responses. In the case of neoplasia, this balance is readily perturbed by the dramatic expansion of immature or dysfunctional myeloid cells accompanied by a reciprocal decline in the quantity/quality of the lymphoid response. In this review, we seek to: (1) define the nature of the atypical myelopoiesis observed in cancer patients and the impact of this perturbation on clinical outcomes; (2) examine the potential mechanisms underlying these clinical manifestations; and (3) explore potential strategies to restore normal myeloid cell differentiation to improve activation of the host antitumor immune response. We posit that fundamental alterations in myeloid homeostasis triggered by the neoplastic process represent critical checkpoints that govern therapeutic efficacy, as well as offer novel cellular-based biomarkers for tracking changes in disease status or relapse.

Novel approaches to enhance the specificity and safety of engineered T cells

T-cell therapies using engineered T cells show great promise for cancer immunotherapy, as illustrated by the CD19 paradigm. Much of the excitement about this approach, and second-generation CARs in particular, is due to the dramatic clinical results recently reported by a few centers, especially in acute lymphoblastic leukemia, and the applicability of this approach, in principle, to a wide range of cancers. Extending the use of CAR therapies to cancers other than B-cell malignancies will require selective tumor targeting with minimal or acceptable "on-target, off-tumor" effects. The identification of new CAR target antigens is thus one of the next big challenges to address. Recognizing the paucity of currently available tumor-specific targets, we have developed broadly applicable approaches to enhance the tumor selectivity and safety of engineered T cells. Here, we review 2 promising concepts. One is to improve tumor targeting based on combinatorial antigen recognition. The other uses receptors that provide antigen-specific inhibition, which we named iCARs, to divert T cells from the normal tissues one wants to protect.

Cancer Immunotherapy Using γδT Cells: Dealing with Diversity

The broad and potent tumor-reactivity of innate-like γδT cells makes them valuable additions to current cancer immunotherapeutic concepts based on adaptive immunity, such as monoclonal antibodies and αβT cells. However, clinical success using γδT cells to treat cancer has so far fallen short. Efforts of recent years have revealed a striking diversity in γδT cell functions and immunobiology, putting these cells forward as true “swiss army knives” of immunity. At the same time, however, this heterogeneity poses new challenges to the design of γδT cell-based therapeutic concepts and could explain their rather limited clinical efficacy in cancer patients. This review outlines the recent new insights into the different levels of γδT cell diversity, including the myriad of γδT cell-mediated immune functions, the diversity of specificities and affinities within the γδT cell repertoire, and the multitude of complex molecular requirements for γδT cell activation. A careful consideration of the diversity of antibodies and αβT cells has delivered great progress to their clinical success; addressing also the extraordinary diversity in γδT cells will therefore hold the key to more effective immunotherapeutic strategies with γδT cells as additional and valuable tools to battle cancer.

Universes collide: combining immunotherapy with targeted therapy for cancer

There have been significant advances in the past several years with regard to targeted therapy and immunotherapy for cancer. This is highlighted in melanoma, where treatment with targeted therapy (against the BRAF oncoprotein) results in responses in the majority of patients, although the duration of response is limited. In contrast, treatment with immunotherapy results in a lower response rate, but one that tends to be more durable. Insights about mechanisms of response and potential synergy between these treatment strategies for melanoma are a focus of this review, with opportunities to extend these insights to the treatment of other cancers.

SIGNIFICANCE

Two major advances in melanoma have occurred concurrently and involve treatment with targeted therapy and immune checkpoint blockade. However, each of these approaches has limitations with regard to overall response rates or duration of response. To address this, investigators have proposed combining these strategies, and this concept is being tested empirically in clinical trials. There is a scientific rationale supporting the combination of targeted therapy and immunotherapy, and these concepts are discussed herein.

Combination of 4-1BB agonist and PD-1 antagonist promotes antitumor effector/memory CD8 T cells in a poorly immunogenic tumor model

Immunotherapies targeting the programmed death 1 (PD-1) coinhibitory receptor have shown great promise for a subset of patients with cancer. However, robust and safe combination therapies are still needed to bring the benefit of cancer immunotherapy to broader patient populations. To search for an optimal strategy of combinatorial immunotherapy, we have compared the antitumor activity of the anti-4-1BB/anti-PD-1 combination with that of the anti-PD-1/anti-LAG-3 combination in the poorly immunogenic B16F10 melanoma model. Pronounced tumor inhibition occurred only in animals receiving anti-PD-1 and anti-4-1BB concomitantly, while combining anti-PD-1 with anti-LAG-3 led to a modest degree of tumor suppression. The activity of the anti-4-1BB/anti-PD-1 combination was dependent on IFNγ and CD8(+) T cells. Both 4-1BB and PD-1 proteins were elevated on the surface of CD8(+) T cells by anti-4-1BB/anti-PD-1 cotreatment. In the tumor microenvironment, an effective antitumor immune response was induced as indicated by the increased CD8(+)/Treg ratio and the enrichment of genes such as Cd3e, Cd8a, Ifng, and Eomes. In the spleen, the combination treatment shaped the immune system to an effector/memory phenotype and increased the overall activity of tumor-specific CD8(+) CTLs, reflecting a long-lasting systemic antitumor response. Furthermore, combination treatment in C57BL/6 mice showed no additional safety signals, and only minimally increased severity of the known toxicity relative to 4-1BB agonist alone. Therefore, in the absence of any cancer vaccine, anti-4-1BB/anti-PD-1 combination therapy is sufficient to elicit a robust antitumor effector/memory T-cell response in an aggressive tumor model and is therefore a candidate for combination trials in patients.

"Glowing head" mice: a genetic tool enabling reliable preclinical image-based evaluation of cancers in immunocompetent allografts

Preclinical therapeutic assessment currently relies on the growth response of established human cell lines xenografted into immunocompromised mice, a strategy that is generally not predictive of clinical outcomes. Immunocompetent genetically engineered mouse (GEM)-derived tumor allograft models offer highly tractable preclinical alternatives and facilitate analysis of clinically promising immunomodulatory agents. Imageable reporters are essential for accurately tracking tumor growth and response, particularly for metastases. Unfortunately, reporters such as luciferase and GFP are foreign antigens in immunocompetent mice, potentially hindering tumor growth and confounding therapeutic responses. Here we assessed the value of reporter-tolerized GEMs as allograft recipients by targeting minimal expression of a luciferase-GFP fusion reporter to the anterior pituitary gland (dubbed the "Glowing Head" or GH mouse). The luciferase-GFP reporter expressed in tumor cells induced adverse immune responses in wildtype mouse, but not in GH mouse, as transplantation hosts. The antigenicity of optical reporters resulted in a decrease in both the growth and metastatic potential of the labeled tumor in wildtype mice as compared to the GH mice. Moreover, reporter expression can also alter the tumor response to chemotherapy or targeted therapy in a context-dependent manner. Thus the GH mice and experimental approaches vetted herein provide concept validation and a strategy for effective, reproducible preclinical evaluation of growth and response kinetics for traceable tumors.

Interleukin-15 in the treatment of cancer

IL-15 is a 14-15 kDa member of the four α-helix bundle of cytokines that acts through a heterotrimeric receptor involving IL-2/IL-15R β, γc and the IL-15 specific receptor subunit IL-15R α. IL-15 stimulates the proliferation of T, B and NK cells, and induces stem, central and effector memory CD8 T cells. In rhesus macaques, continuous infusion of recombinant human IL-15 at 20 μg/kg/day was associated with approximately a 10-fold increase in the numbers of circulating NK, γ/δ cells and monocytes, and an 80- to 100-fold increase in the numbers of effector memory CD8 T cells. IL-15 has shown efficacy in murine models of malignancy. Clinical trials involving recombinant human IL-15 given by bolus infusions have been completed and by subcutaneous and continuous intravenous infusions are underway in patients with metastatic malignancy. Furthermore, clinical trials are being initiated that employ the combination of IL-15 with IL-15R α(+/-) IgFc.

A validated mathematical model of tumor growth including tumor-host interaction, cell-mediated immune response and chemotherapy

We consider a dynamical model of cancer growth including three interacting cell populations of tumor cells, healthy host cells and immune effector cells. The tumor-immune and the tumor-host interactions are characterized to reproduce experimental results. A thorough dynamical analysis of the model is carried out, showing its capability to explain theoretical and empirical knowledge about tumor development. A chemotherapy treatment reproducing different experiments is also introduced. We believe that this simple model can serve as a foundation for the development of more complicated and specific cancer models.

Copy number loss of the interferon gene cluster in melanomas is linked to reduced T cell infiltrate and poor patient prognosis

While immunotherapies are rapidly becoming mainstays of cancer treatment, significant gaps remain in our understanding of how to optimally target them, alone or in combination. Here we describe a novel method to monitor levels of immune cells and pathways in expression data from solid tumors using pre-defined groups or modules of co-regulated immune genes. We show that expression of an interconnected sub-network of type I interferon-stimulated genes (ISGs) in melanomas at the time of diagnosis significantly predicted patient survival, as did, to a lesser extent, sub-networks of T helper/T regulatory and NK/T Cytotoxic cell genes. As a group, poor prognosis tumors with reduced ISG and immune gene levels exhibited significant copy number loss of the interferon gene cluster located at chromosome 9p21.3. Our studies demonstrate a link between type I interferon action and immune cell levels in melanomas, and suggest that therapeutic approaches augmenting both activities may be most beneficial.