Immune checkpoint modulation: rational design of combination strategies. Pharmacol Ther. 2015;150:23-32. [PMID: 25583297 DOI: 10.1016/j.pharmthera.2015.01.003]

Tumor-associated macrophages in anti-PD-1/PD-L1 immunotherapy for hepatocellular carcinoma: recent research progress

Hepatocellular carcinoma (HCC) is one of the cancers that seriously threaten human health. Immunotherapy serves as the mainstay of treatment for HCC patients by targeting the programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) axis. However, the effectiveness of anti-PD-1/PD-L1 treatment is limited when HCC becomes drug-resistant. Tumor-associated macrophages (TAMs) are an important factor in the negative regulation of PD-1 antibody targeted therapy in the tumor microenvironment (TME). Therefore, as an emerging direction in cancer immunotherapy research for the treatment of HCC, it is crucial to elucidate the correlations and mechanisms between TAMs and PD-1/PD-L1-mediated immune tolerance. This paper summarizes the effects of TAMs on the pathogenesis and progression of HCC and their impact on HCC anti-PD-1/PD-L1 immunotherapy, and further explores current potential therapeutic strategies that target TAMs in HCC, including eliminating TAMs in the TME, inhibiting TAMs recruitment to tumors and functionally repolarizing M2-TAMs (tumor-supportive) to M1-TAMs (antitumor type).

Phytochemicals in regulating PD-1/PD-L1 and immune checkpoint blockade therapy

Clinical treatment and preclinical studies have highlighted the role of immune checkpoint blockade in cancer treatment. Research has been devoted to developing immune checkpoint inhibitors in combination with other drugs to achieve better efficacy or reduce adverse effects. Phytochemicals sourced from vegetables and fruits have demonstrated antiproliferative, proapoptotic, anti-migratory, and antiangiogenic effects against several cancers. Phytochemicals also modulate the tumor microenvironment such as T cells, regulatory T cells, and cytokines. Recently, several phytochemicals have been reported to modulate immune checkpoint proteins in in vivo or in vitro models. Phytochemicals decreased programmed cell death ligand-1 expression and synergized programmed cell death receptor 1 (PD-1) monoclonal antibody to suppress tumor growth. Combined administration of phytochemicals and PD-1 monoclonal antibody enhanced the tumor growth inhibition as well as CD4+ /CD8+ T-cell infiltration. In this review, we discuss immune checkpoint molecules as potential therapeutic targets of cancers. We further assess the impact of phytochemicals including carotenoids, polyphenols, saponins, and organosulfur compounds on cancer PD-1/programmed cell death ligand-1 immune checkpoint molecules and document their combination effects with immune checkpoint inhibitors on various malignancies.

Overcoming anti-PD-1/PD-L1 immune checkpoint blockade resistance: the role of macrophage, neutrophils and mast cells in the tumor microenvironment

In recent years, the anti-PD-1/PD-L1 blockade has become a game changer in cancer treatment following the unprecedented response rate. Regardless of the substantial therapy efficacy across various cancer types, some patients do not still respond to these therapies, indicating that a deeper understanding of the mechanisms of anti-PD-1/PD-L1 resistance is highly important. To overcome such resistance, the tumor-induced immunosuppressive mechanisms have been focused and several suppressor cell populations in the tumor microenvironment have been identified. Among these cells, macrophages, neutrophils, and mast cells are known to play key roles in anti-PD-1/PD-L1 resistance. Hence, gaining control over these innate immune cells can open opportunities for breaking tumor resistance to immune checkpoint inhibitors. Herein, a summary of the role of macrophages, neutrophils, and mast cells in anti-PD-1/PD-L1 resistance has been described. Also, strategies to overcome their therapeutic resistance to anti-PD-1/PD-L1 have been discussed.

Integration of bioinformatics and machine learning strategies identifies APM-related gene signatures to predict clinical outcomes and therapeutic responses for breast cancer patients

BACKGROUND

Tumor antigenicity and efficiency of antigen presentation jointly influence tumor immunogenicity, which largely determines the effectiveness of immune checkpoint blockade (ICB). However, the role of altered antigen processing and presentation machinery (APM) in breast cancer (BRCA) has not been fully elucidated.

METHODS

A series of bioinformatic analyses and machine learning strategies were performed to construct APM-related gene signatures to guide personalized treatment for BRCA patients. A single-sample gene set enrichment analysis (ssGSEA) algorithm and weighted gene co-expression network analysis (WGCNA) were combined to screen for BRCA-specific APM-related genes. The non-negative matrix factorization (NMF) algorithm was used to divide the cohort into different clusters and the fgsea algorithm was applied to investigate the altered signaling pathways. Random survival forest (RSF) and the least absolute shrinkage and selection operator (Lasso) Cox regression analysis were combined to construct an APM-related risk score (APMrs) signature to predict overall survival. Furthermore, a nomogram and decision tree were generated to improve predictive accuracy and risk stratification for individual patients. Based on Tumor Immune Dysfunction and Exclusion (TIDE) method, random forest (RF) and Lasso logistic regression model were combined to establish an APM-related immunotherapeutic response score (APMis). Finally, immune infiltration, immunomodulators, mutational patterns, and potentially applicable drugs were comprehensively analyzed in different APM-related risk groups. IHC staining was used to assess the expression of APM-related genes in clinical samples.

RESULTS

In this study, APMrs and APMis showed favorable performances in risk stratification and therapeutic prediction for BRCA patients. APMrs exhibited more powerful prognostic capacity and accurate survival prediction compared to conventional clinicopathological features. APMrs was closely associated with distinct mutational patterns, immune cell infiltration and immunomodulators expression. Furthermore, the two APM-related gene signatures were independently validated in external cohorts with prognosis or immunotherapeutic responses. Potential applicable drugs and targets were mined in the APMrs-high group. APM-related genes were further validated in our in-house samples.

CONCLUSION

The APM-related gene signatures established in our study could improve the personalized assessment of survival risk and guide ICB decision-making for BRCA patients.

Correlation between PD-1/PD-L1 expression and polarization in tumor-associated macrophages: A key player in tumor immunotherapy

Tumor immunotherapy, such as PD-1/PD-L1 blockade, has shown promising clinical efficacy in patients with various types of tumors. However, the response to PD-1/PD-L1 blockade in a majority of malignancies is limited, indicating an urgent need for a deeper understanding of the mechanisms of PD-1/PD-L1 axis-mediated tumor tolerance. As the most abundant immune cells in the tumor stroma, macrophages display multiple phenotypes and functions in response to the stimuli of the tumor microenvironment. PD-1/PD-L1 has been demonstrated to be highly expressed in tumor-associated macrophages (TAMs), and TAM polarization has been shown to be important during tumor progression. In this review, we outline the relationship between TAM PD-1/PD-L1 expression and polarizations, summarize the involvement of M2 TAMs in PD-1/PD-L1-mediated T-cell exhaustion, and discuss improved approaches for overcoming PD-1/PD-L1 blockade resistance by inducing M2/M1 switching of TAMs.

The Role of Toll-like Receptor Agonists and Their Nanomedicines for Tumor Immunotherapy

Toll-like receptors (TLRs) are a class of pattern recognition receptors that play a critical role in innate and adaptive immunity. Toll-like receptor agonists (TLRa) as vaccine adjuvant candidates have become one of the recent research hotspots in the cancer immunomodulatory field. Nevertheless, numerous current systemic deliveries of TLRa are inappropriate for clinical adoption due to their low efficiency and systemic adverse reactions. TLRa-loaded nanoparticles are capable of ameliorating the risk of immune-related toxicity and of strengthening tumor suppression and eradication. Herein, we first briefly depict the patterns of TLRa, followed by the mechanism of agonists at those targets. Second, we summarize the emerging applications of TLRa-loaded nanomedicines as state-of-the-art strategies to advance cancer immunotherapy. Additionally, we outline perspectives related to the development of nanomedicine-based TLRa combined with other therapeutic modalities for malignancies immunotherapy.

Lactoferrin: A Nutraceutical with Activity against Colorectal Cancer

Homeostasis in the human body results from the tight regulation of several events, since too little inflammation disrupts the process of tissue repair and remodeling, whereas too much exerts a collateral effect by causing tissue damage with life-threatening consequences. In some clinical conditions, such as inflammatory bowel disease (IBD), inflammation functions as a double-edged sword by either enabling or inhibiting cancer development and progression. Generally, cancer develops through evasion mechanisms that regulate cell growth, causing a high rate of uncontrolled proliferation, and mechanisms for evading cell death, such as apoptosis. Moreover, chronic inflammation is a factor that contributes to colorectal cancer (CRC), as observed in individuals with IBD; all these conditions favor an increased rate of angiogenesis and eventual metastasis. Lactoferrin (Lf) is a mammalian iron-binding multifunctional glycoprotein regarded as a natural compound that up- and downregulates both humoral and cellular components of immunity involved in regulating the inflammatory response and maintaining gut homeostasis. Human and bovine Lf share high sequence homology and have very similar antimicrobial, anti-inflammatory, and immunomodulatory activities. Bovine Lf from milk is considered a safe molecule and is commercially available in large quantities. This review mainly focuses on the regulatory effects of orally administered bovine Lf on the inflammatory response associated with CRC; this approach indicates that CRC is one of the most frequently diagnosed cancers and affects the intestinal tract with high clinical and epidemiologic relevance. Thus, this review may provide foundations for the potential use of bovine Lf alone or as a natural adjunct agent to increase the effectiveness and reduce the side effects of anticancer chemotherapy.

Belantamab Mafodotin (GSK2857916) Drives Immunogenic Cell Death and Immune-mediated Antitumor Responses In Vivo

B-cell maturation antigen (BCMA) is an attractive therapeutic target highly expressed on differentiated plasma cells in multiple myeloma and other B-cell malignancies. GSK2857916 (belantamab mafodotin, BLENREP) is a BCMA-targeting antibody-drug conjugate approved for the treatment of relapsed/refractory multiple myeloma. We report that GSK2857916 induces immunogenic cell death in BCMA-expressing cancer cells and promotes dendritic cell activation in vitro and in vivo GSK2857916 treatment enhances intratumor immune cell infiltration and activation, delays tumor growth, and promotes durable complete regressions in immune-competent mice bearing EL4 lymphoma tumors expressing human BCMA (EL4-hBCMA). Responding mice are immune to rechallenge with EL4 parental and EL4-hBCMA cells, suggesting engagement of an adaptive immune response, immunologic memory, and tumor antigen spreading, which are abrogated upon depletion of endogenous CD8⁺ T cells. Combinations with OX40/OX86, an immune agonist antibody, significantly enhance antitumor activity and increase durable complete responses, providing a strong rationale for clinical evaluation of GSK2857916 combinations with immunotherapies targeting adaptive immune responses, including T-cell-directed checkpoint modulators.

A preclinical study: correlation between PD-L1 PET imaging and the prediction of therapy efficacy of MC38 tumor with 68Ga-labeled PD-L1 targeted nanobody

Although immunotherapy has achieved great clinical success in clinical outcomes, especially the anti-PD-1 or anti-PD-L1 antibodies, not all patients respond to anti-PD-1 immunotherapy. It is urgently required for a clinical diagnosis to develop non-invasive imaging meditated strategy for assessing the expression level of PD-L1 in tumors. In this work, a ⁶⁸Ga-labeled single-domain antibody tracer, ⁶⁸Ga-NOTA-Nb109, was designed for specific and noninvasive imaging of PD-L1 expression in an MC38 tumor-bearing mouse model. Comprehensive studies including Positron Emission Tomography (PET), biodistribution, blocking studies, immunohistochemistry, and immunotherapy, have been performed in differences PD-L1 expression tumor-bearing models. These results revealed that ⁶⁸Ga-NOTA-Nb109 specifically accumulated in the MC38-hPD-L1 tumor. The content of this nanobody in MC38 hPD-L1 tumor and MC38 Mixed tumor was 8.2 ± 1.3, 7.3 ± 1.2, 3.7 ± 1.5, 2.3 ± 1.2%ID/g and 7.5 ± 1.4, 3.6 ± 1.7, 1.7 ± 0.6, 1.2 ± 0.5%ID/g at 0.5, 1, 1.5, 2 hours post-injection, respectively. ⁶⁸Ga-NOTA-Nb109 has the potential to further noninvasive PET imaging and therapy effectiveness assessments based on the PD-L1 status in tumors. To explore the possible synergistic effects of immunotherapy combined with chemotherapy, MC38 xenografts with different sensitivity to PD-L1 blockade were established. In addition, we found that PD-1 blockade also had efficacy on the PD-L1 knockout tumors. RT-PCR and immunofluorescence analysis were used to detect the expression of PD-L1. It was observed that both mouse and human PD-L1 expressed among three types of MC38 tumors. These results suggest that PD-L1 on tumor cells affect the efficacy, but it on host myeloid cells might be essential for checkpoint blockade. Moreover, anti–PD-1 treatment activates tumor-reactive CD103⁺ CD39⁺ CD8+T cells (TILs) in tumor microenvironment.

Translational genomics of ovarian clear cell carcinoma

Ovarian clear cell carcinomas (OCCC) are rare aggressive, chemo-resistant tumours comprising approximately 13% of all epithelial ovarian cancers, which have distinct clinical and molecular features, when compared to other gynaecological malignancies. At present, there are no specific licensed targeted therapies for OCCC, although a number of candidate targets have been identified. This review focuses on recent knowledge underpinning our understanding of the pathogenesis of OCCC including direct and synthetic-lethal therapeutic strategies in particular focussing on ARID1A deficiency. We also discuss current targeted clinical trials and immunotherapeutic approaches.

Design, synthesis, and biological evaluation of 1,2,5-oxadiazole-3-carboximidamide derivatives as novel indoleamine-2,3-dioxygenase 1 inhibitors

Indoleamine 2,3-dioxygenase 1 (IDO1) is the enzyme catalyzing the oxidative metabolism of tryptophan, which accounts for cancer immunosuppression in tumor microenvironment. Several compounds targeting IDO1 have been reported and epacadostat shows strong inhibitory activity against IDO1, which is further studied in clinic trails. However, its pharmacokinetic profiles are not satisfactory. The half-life of epacadostat is 2.4 h in human and dosage is 50 mg BID in the phase III clinic trial. To overcome the shortcomings of epacadostat, structure-based drug design was performed to improve the pharmacokinetic profiles via changing the metabolic pathway of epacadostat and to enhance anti-tumor potency. A novel series of 1,2,5-oxadiazole-3-carboximidamide derivatives bearing cycle in the side chain were designed, synthesized, and biologically evaluated for their anti-tumor activity. Most of them exhibited potent activity against hIDO1 in enzymatic assays and in HEK293T cells over-expressing hIDO1. Among them, compound 23, 25 and 26 showed significant inhibitory activity against hIDO1 (IC₅₀ = 108.7, 178.1 and 139.1 nM respectively) and in HEK293T cells expressing hIDO1 (cellular IC₅₀ = 19.88, 68.59 and 57.76 nM respectively). Moreover, compound 25 displayed improved PK property with longer half-life (t_1/2 = 3.81 h in CD-1 mice) and better oral bioavailability (F = 33.6%) compared with epacadostat. In addition, compound 25 showed similar potency to inhibit the growth of CT-26 syngeneic xenograft compared to epacadostat, making it justifiable for further investigation.

High Affinity of Chlorin e6 to Immunoglobulin G for Intraoperative Fluorescence Image-Guided Cancer Photodynamic and Checkpoint Blockade Therapy

Cancer photodynamic therapy (PDT) represents an attractive local treatment in combination with immunotherapy. Successful cancer PDT relies on image guidance to ensure the treatment accuracy. However, existing nanotechnology for co-delivery of photosensitizers and image contrast agents slows the clearance of PDT agents from the body and causes a disparity between the release profiles of the imaging and PDT agents. We have found that the photosensitizer Chlorin e6 (Ce6) is inherently bound to immunoglobulin G (IgG) in a nanomolarity range of affinity. Ce6 and IgG self-assemble to form the nanocomplexes termed Chloringlobulin (Chlorin e6 + immunoglobulin G). Chloringlobulin enhances the Ce6 concentration in the tumor without changing its elimination half-life in blood. Utilizing the immune checkpoint inhibitor antiprogrammed death ligand 1 (PD-L1) (αPD-L1) to prepare αPD-L1 Chloringlobulin, we have demonstrated a combination of Ce6-based red-light fluorescence image-guided surgery, stereotactic PDT, and PD-L1 blockade therapy of mice bearing orthotopic glioma. In mice bearing an orthotopic colon cancer model, we have prepared another Chloringlobulin that allows intraoperative fluorescence image-guided PDT in combination with PD-L1 and cytotoxic T lymphocyte antigen 4 (CTLA-4) dual checkpoint blockade therapy. The Chloringlobulin technology shows great potential for clinical translation of combinatorial intraoperative fluorescence image-guided PDT and checkpoint blockade therapy.

Breaking Therapy Resistance: An Update on Oncolytic Newcastle Disease Virus for Improvements of Cancer Therapy

Resistance to therapy is a major obstacle to cancer treatment. It may exist from the beginning, or it may develop during therapy. The review focusses on oncolytic Newcastle disease virus (NDV) as a biological agent with potential to break therapy resistance. This avian virus combines, upon inoculation into non-permissive hosts such as human, 12 described anti-neoplastic effects with 11 described immune stimulatory properties. Fifty years of clinical application of NDV give witness to the high safety profile of this biological agent. In 2015, an important milestone was achieved, namely the successful production of NDV according to Good Manufacturing Practice (GMP). Based on this, IOZK in Cologne, Germany, obtained a GMP certificate for the production of a dendritic cell vaccine loaded with tumor antigens from a lysate of patient-derived tumor cells together with immunological danger signals from NDV for intracutaneous application. This update includes single case reports and retrospective analyses from patients treated at IOZK. The review also presents future perspectives, including the concept of in situ vaccination and the combination of NDV or other oncolytic viruses with checkpoint inhibitors.

An Oncolytic Adenovirus Targeting Transforming Growth Factor β Inhibits Protumorigenic Signals and Produces Immune Activation: A Novel Approach to Enhance Anti-PD-1 and Anti-CTLA-4 Therapy

In an effort to develop a new therapy for cancer and to improve antiprogrammed death inhibitor-1 (anti-PD-1) and anticytotoxic T lymphocyte-associated protein (anti-CTLA-4) responses, we have created a telomerase reverse transcriptase promoter-regulated oncolytic adenovirus rAd.sT containing a soluble transforming growth factor receptor II fused with human IgG Fc fragment (sTGFβRIIFc) gene. Infection of breast and renal tumor cells with rAd.sT produced sTGFβRIIFc protein with dose-dependent cytotoxicity. In immunocompetent mouse 4T1 breast tumor model, intratumoral delivery of rAd.sT inhibited both tumor growth and lung metastases. rAd.sT downregulated the expression of several transforming growth factor β (TGFβ) target genes involved in tumor growth and metastases, inhibited Th2 cytokine expression, and induced Th1 cytokines and chemokines, and granzyme B and perforin expression. rAd.sT treatment also increased the percentage of CD8⁺ T lymphocytes, promoted the generation of CD4⁺ T memory cells, reduced regulatory T lymphocytes (Tregs), and reduced bone marrow-derived suppressor cells. Importantly, rAd.sT treatment increased the percentage of CD4⁺ T lymphocytes, and promoted differentiation and maturation of antigen-presenting dendritic cells in the spleen. In the immunocompetent mouse Renca renal tumor model, similar therapeutic effects and immune activation results were observed. In the 4T1 mammary tumor model, rAd.sT improved the inhibition of tumor growth and lung and liver metastases by anti-PD-1 and anti-CTLA-4 antibodies. Analysis of the human breast and kidney tumors showed that a significant number of tumor tissues expressed high levels of TGFβ and TGFβ-inducible genes. Therefore, rAd.sT could be a potential enhancer of anti-PD-1 and anti-CTLA-4 therapy for treating breast and kidney cancers.

Human Immune System Increases Breast Cancer-Induced Osteoblastic Bone Growth in a Humanized Mouse Model without Affecting Normal Bone

Bone metastases are prevalent in many common cancers such as breast, prostate, and lung cancers, and novel therapies for treating bone metastases are needed. Human immune system-engrafted models are used in immuno-oncology (IO) studies for subcutaneous cancer cell or patient-derived xenograft implantations that mimic primary tumor growth. Novel efficacy models for IO compounds on bone metastases need to be established. The study was performed using CIEA NOG (NOG) mice engrafted with human CD34+ hematopoietic stem cells (huNOG) and age-matched immunodeficient NOG mice. Bone phenotyping was performed to evaluate baseline differences. BT-474 human breast cancer cells were inoculated into the tibia bone marrow, and cancer-induced bone changes were monitored by X-ray imaging. Bone content and volume were analyzed by dual X-ray absorptiometry and microcomputed tomography. Tumor-infiltrating lymphocytes (TILs) and the expression of immune checkpoint markers were analyzed by immunohistochemistry. Bone phenotyping showed no differences in bone architecture or volume of the healthy bones in huNOG and NOG mice, but the bone marrow fat was absent in huNOG mice. Fibrotic areas were observed in the bone marrow of some huNOG mice. BT-474 tumors induced osteoblastic bone growth. Bone lesions appeared earlier and were larger, and bone mineral density was higher in huNOG mice. huNOG mice had a high number of human CD3-, CD4-, and CD8-positive T cells and CD20-positive B cells in immune-related organs. A low number of TILs and PD-1-positive cells and low PD-L1 expression were observed in the BT-474 tumors at the endpoint. This study reports characterization of the first breast cancer bone growth model in huNOG mice. BT-474 tumors represent a “cold” tumor with a low number of TILs. This model can be used for evaluating the efficacy of combination treatments of IO therapies with immune-stimulatory compounds or therapeutic approaches on bone metastatic breast cancer.

Ap4A Regulates Directional Mobility and Antigen Presentation in Dendritic Cells

The significance of intracellular Ap₄A levels over immune activity of dendritic cells (DCs) has been studied in Nudt2^fl/fl/CD11c-cre mice. The transgenic mice have been generated by crossing floxed NUDT2 gene mice with DC marker CD11c recombinase (cre) mice. The DCs derived from these mice have higher levels of Ap₄A (≈30-fold) compared with those derived from Nudt2^+/+ mice. Interestingly, the elevated Ap₄A in DCs has led them to possess higher motility and lower directional variability. In addition, the DCs are able to enhance immune protection indicated by the higher cross-presentation of antigen and priming of CD8⁺ OT-I T cells. Overall, the study denotes prominent impact of Ap₄A over the functionality of DCs. The Nudt2^fl/fl/CD11c-cre mice could serve as a useful tool to study the influence of Ap₄A in the critical immune mechanisms of DCs.

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DCs of Nudt2^fl/fl/CD11c-cre mice exhibit low directional variability and high motility

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DCs elevate proliferation of OVA-specific T cell receptor transgenic CD8⁺ T cells

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The escalation of Ap₄A levels in DCs could enhance their immune protective activity

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Mice can serve as useful functional tool to study the role of Ap₄A in various cells

STAT3 Contributes To Oncolytic Newcastle Disease Virus-Induced Immunogenic Cell Death in Melanoma Cells

Background: Oncolytic viruses (OVs) are emerging as potent inducers of immunogenic cell death (ICD), releasing danger-associated molecular patterns (DAMPs) that induce potent anticancer immunity. Oncolytic Newcastle disease virus (NDV) has been shown to educe ICD in both glioma and lung cancer cells. The objective of this study is to investigate whether oncolytic NDV induces ICD in melanoma cells and how it is regulated.

Methods: Various time points were actuated to check the expression and release of ICD markers induced by NDV strain, NDV/FMW in melanoma cell lines. The expression and release of ICD markers induced by oncolytic NDV strain, NDV/FMW, in melanoma cell lines at various time points were determined. Surface-exposed calreticulin (CRT) was inspected by confocal imaging. The supernatants of NDV/FMW infected cells were collected and concentrated for the determination of ATP secretion by ELISA, HMGB1, and HSP70/90 expression by immunoblot (IB) analysis. Pharmacological inhibition of apoptosis, autophagy, necroptosis, ER Stress, and STAT3 (signal transducer and activator of transcription 3) was achieved by treatment with small molecule inhibitors. Melanoma cell lines stably depleted of STAT3 were established with lentiviral constructs. Supernatants from NDV-infected cells were intratumorally injected to mice bearing melanoma cells-derived tumors.

Results: Oncolytic NDV induced CRT exposure, the release of HMGB1 and HSP70/90 as well as secretion of ATP in melanoma cells. Inhibition of apoptosis, autophagy, necroptosis or ER stress attenuated NDV/FMW-induced release of HMGB1 and HSP70/90. Moreover, NDV/FMW-induced ICD markers in melanoma cells were also suppressed by either treatment with a STAT3 inhibitor or shRNA-mediated depletion of STAT3. Of translational importance, treatment of mice bearing melanoma cells-derived tumors with supernatants from NDV/FMW-infected cells significantly inhibited tumor growth.

Conclusions: Our data authenticate that oncolytic NDV/FMW might be a potent inducer of ICD in melanoma cells, which is amalgamated with several forms of cell death. We also show that STAT3 plays a role in NDV/FMW-induced ICD in melanoma cells. Together, our data highlight oncolytic NDV as propitious for cancer therapeutics by stimulatingan anti-melanoma immune response.

Noninvasive Imaging and Quantification of Radiotherapy-Induced PD-L1 Upregulation with 89Zr-Df-Atezolizumab

Immune checkpoint expression is highly dynamic, and combination treatments including radiotherapy can particularly modulate this expression. PET imaging using ⁸⁹Zr-Df-atezolizumab can provide insight into the levels of PD-L1 variation following radiotherapy treatments. In vitro screening was used to monitor PD-L1 expression by lung cancer cells following radiotherapy. Mice bearing PD-L1+ (H460) or PD-L1- (A549) tumors were subjected to various external beam radiotherapy regimens and then imaged using ⁸⁹Zr-Df-atezolizumab PET. ROI analysis and ex vivo biodistribution studies were employed to quantify tracer accumulations. H460 cells were found to have PD-L1 expression at baseline, and this expression increased following daily radiotherapy of 5 fractions of 2 Gy. PD-L1 expression could not be induced on A549 cells, regardless of radiotherapy regimen. The increase in PD-L1 expression in H460 tumors following fractionated radiotherapy could be imaged in vivo using ⁸⁹Zr-Df-atezolizumab, with statistically significant higher tracer accumulation noted in fractionated H460 tumors over that in all other H460 or A549 groups after 72 h postinjection of the tracer. Significant accumulation of the tracer was also noted in other PD-L1+ organs, including the spleen and lymph nodes. Ex vivo staining of tumor tissues verified that tumor cells as well as tumor-infiltrating immune cells were responsible for increased PD-L1 expression after radiotherapy in tumor tissues. Overall, PD-L1 expression can be modulated with radiotherapy interventions, and ⁸⁹Zr-Df-atezolizumab is able to noninvasively monitor these changes in preclinical models.

Combination Immune Checkpoint Blockade Strategies to Maximize Immune Response in Gynecological Cancers

PURPOSE OF REVIEW

Immune checkpoint blockade targeting PD-1 and PD-L1 improves immune recognition of tumor cells but had only modest success in gynecological cancers as monotherapy. Growing focus has been placed on combination immunotherapy strategies to overcome this resistance, and this review serves to discuss some of the most promising studies in gynecological cancers.

RECENT FINDINGS

PD-1- and PD-L1-targeting antibodies are being combined with many novel agents including anti-CTLA-4 antibodies, PARP inhibitors, targeted agents, and traditional chemotherapy in promising studies with the hopes of increasing the immune response and overcoming resistance by targeting other pathways. Novel immune techniques including vaccines and adoptive cell therapies are also being implemented in gynecological cancers. Immune checkpoint combinations and novel immunotherapy strategies have demonstrated potential to overcome resistance to PD-1/PD-L1 blockade in gynecological cancers. Identification of biomarkers of response and resistance is a priority to tailor specific combination therapies to the appropriate patients.

Clinical Applications of Immunotherapy Combination Methods and New Opportunities for the Future

In the last decade, we have gained a deeper understanding of innate immune system. The mechanism of the continuous guarding of progressive mutations happening in a single cell was discovered and the production and the recognition of tumor associated antigens by the T-cells and elimination of numerous tumors by immune-editing were further understood. The new discoveries on immune mechanisms and its relation with carcinogenesis have led to development of a new class of drugs called immunotherapeutics. T lymphocyte-associated antigen 4, programmed cell death protein 1, and programmed cell death protein ligand 1 are the classes drugs based on immunologic manipulation and are collectively known as the "checkpoint inhibitors." Checkpoint inhibitors have shown remarkable antitumor efficacy in a broad spectrum of malignancies; however, the strongest and most durable immune responses do not last long and the more durable responses only occur in a small subset of patients. One of the solutions which have been put forth to overcome these challenges is combination strategies. Among the dual use of methods, a backbone with either PD-1 or PD-L1 antagonist drugs alongside with certain cytotoxic chemotherapies, radiation, targeted drugs, and novel checkpoint stimulators is the most promising approach and will be on stage in forthcoming years.

Chemotherapy oxaliplatin sensitizes prostate cancer to immune checkpoint blockade therapies via stimulating tumor immunogenicity

Even though standard treatment options are available for prostate cancer patients, prostate cancer is still a leading cause of death in many Western countries due to drug resistance and recurrence. Immune checkpoint blockade therapy has been proved to be very effective in some melanoma patients, which might dependent on the preconditioned immune system. Here we explored the effect of chemotherapy (oxaliplatin) in combination with immune checkpoint blockade therapy (anti‑PD‑1 treatment) in prostate cancer cell lines and pre‑clinical animal models. We found that oxaliplatin is effective in castration‑resistant cells and enhanced the response of prostate cancer to anti‑PD‑1 antibody treatment. Oxaliplatin stimulated the immunogenic potential and established a pro‑immune microenvironment in prostate cancer. In conclusion, oxaliplatin sensitized anti‑PD‑1 treatment in prostate cancer and this combination may be an option for castration‑resistant prostate cancer patients.

Tumor-Localized Secretion of Soluble PD1 Enhances Oncolytic Virotherapy

Oncolytic virotherapy represents an attractive option for the treatment of a variety of aggressive or refractory tumors. While this therapy is effective at rapidly debulking directly injected tumor masses, achieving complete eradication of established disease has proven difficult. One method to overcome this challenge is to use oncolytic viruses to induce secondary antitumor immune responses. Unfortunately, while the initial induction of these immune responses is typically robust, their subsequent efficacy is often inhibited through a variety of immunoregulatory mechanisms, including the PD1/PDL1 T-cell checkpoint pathway. To overcome this inhibition, we generated a novel recombinant myxoma virus (vPD1), which inhibits the PD1/PDL1 pathway specifically within the tumor microenvironment by secreting a soluble form of PD1 from infected cells. This virus both induced and maintained antitumor CD8+ T-cell responses within directly treated tumors and proved safer and more effective than combination therapy using unmodified myxoma and systemic αPD1 antibodies. Localized vPD1 treatment combined with systemic elimination of regulatory T cells had potent synergistic effects against metastatic disease that was already established in secondary solid organs. These results demonstrate that tumor-localized inhibition of the PD1/PDL1 pathway can significantly improve outcomes during oncolytic virotherapy. Furthermore, they establish a feasible path to translate these findings against clinically relevant disease. Cancer Res; 77(11); 2952-63. ©2017 AACR.

Oncolytic Immunotherapy: Conceptual Evolution, Current Strategies, and Future Perspectives

The concept of oncolytic virus (OV)-mediated cancer therapy has been shifted from an operational virotherapy paradigm to an immunotherapy. OVs often induce immunogenic cell death (ICD) of cancer cells, and they may interact directly with immune cells as well to prime antitumor immunity. We and others have developed a number of strategies to further stimulate antitumor immunity and to productively modulate the tumor microenvironment (TME) for potent and sustained antitumor immune cell activity. First, OVs have been engineered or combined with other ICD inducers to promote more effective T cell cross-priming, and in many cases, the breaking of functional immune tolerance. Second, OVs may be armed to express Th1-stimulatory cytokines/chemokines or costimulators to recruit and sustain the potent antitumor immunity into the TME to focus their therapeutic activity within the sites of disease. Third, combinations of OV with immunomodulatory drugs or antibodies that recondition the TME have proven to be highly promising in early studies. Fourth, combinations of OVs with other immunotherapeutic regimens (such as prime-boost cancer vaccines, CAR T cells; armed with bispecific T-cell engagers) have also yielded promising preliminary findings. Finally, OVs have been combined with immune checkpoint blockade, with robust antitumor efficacy being observed in pilot evaluations. Despite some expected hurdles for the rapid translation of OV-based state-of-the-art protocols, we believe that a cohort of these novel approaches will join the repertoire of standard cancer treatment options in the near future.

Engineering challenges for brain tumor immunotherapy

Malignant brain tumors represent one of the most devastating forms of cancer with abject survival rates that have not changed in the past 60years. This is partly because the brain is a critical organ, and poses unique anatomical, physiological, and immunological barriers. The unique interplay of these barriers also provides an opportunity for creative engineering solutions. Cancer immunotherapy, a means of harnessing the host immune system for anti-tumor efficacy, is becoming a standard approach for treating many cancers. However, its use in brain tumors is not widespread. This review discusses the current approaches, and hurdles to these approaches in treating brain tumors, with a focus on immunotherapies. We identify critical barriers to immunoengineering brain tumor therapies and discuss possible solutions to these challenges.

Intratumoral modulation of the inducible co-stimulator ICOS by recombinant oncolytic virus promotes systemic anti-tumour immunity

Emerging data suggest that locoregional cancer therapeutic approaches with oncolytic viruses can lead to systemic anti-tumour immunity, although the appropriate targets for intratumoral immunomodulation using this strategy are not known. Here we find that intratumoral therapy with Newcastle disease virus (NDV), in addition to the activation of innate immunity, upregulates the expression of T-cell co-stimulatory receptors, with the inducible co-stimulator (ICOS) being most notable. To explore ICOS as a direct target in the tumour, we engineered a recombinant NDV-expressing ICOS ligand (NDV-ICOSL). In the bilateral flank tumour models, intratumoral administration of NDV-ICOSL results in enhanced infiltration with activated T cells in both virus-injected and distant tumours, and leads to effective rejection of both tumours when used in combination with systemic CTLA-4 blockade. These findings highlight that intratumoral immunomodulation with an oncolytic virus expressing a rationally selected ligand can be an effective strategy to drive systemic efficacy of immune checkpoint blockade.

Oncolytic viruses induce a variety of immune targets in the infected tumours. Here, the authors show that Newcastle Disease Virus (NDV) upregulates the inducible co-stimulator (ICOS) on T cells and that intratumoral targeting of ICOS with engineered NDV in combination with CTLA-4 blockade induces systemic anti-tumour immunity in mice.

Oncolytic Vesicular Stomatitis Virus as a Viro-Immunotherapy: Defeating Cancer with a "Hammer" and "Anvil"

Oncolytic viruses have gained much attention in recent years, due, not only to their ability to selectively replicate in and lyse tumor cells, but to their potential to stimulate antitumor immune responses directed against the tumor. Vesicular stomatitis virus (VSV), a negative-strand RNA virus, is under intense development as an oncolytic virus due to a variety of favorable properties, including its rapid replication kinetics, inherent tumor specificity, and its potential to elicit a broad range of immunomodulatory responses to break immune tolerance in the tumor microenvironment. Based on this powerful platform, a multitude of strategies have been applied to further improve the immune-stimulating potential of VSV and synergize these responses with the direct oncolytic effect. These strategies include: 1. modification of endogenous virus genes to stimulate interferon induction; 2. virus-mediated expression of cytokines or immune-stimulatory molecules to enhance anti-tumor immune responses; 3. vaccination approaches to stimulate adaptive immune responses against a tumor antigen; 4. combination with adoptive immune cell therapy for potentially synergistic therapeutic responses. A summary of these approaches will be presented in this review.

Talimogene Laherparepvec (T-VEC) and Other Oncolytic Viruses for the Treatment of Melanoma

Many mammalian viruses have properties that can be commandeered for the treatment of cancer. These characteristics include preferential infection and replication in tumor cells, the initiation of tumor cell lysis, and the induction of innate and adaptive anti-tumor immunity. Furthermore, viruses can be genetically engineered to reduce pathogenicity and increase immunogenicity resulting in minimally toxic therapeutic agents. Talimogene laherparepvec (T-VEC; Imlygic™), is a genetically modified herpes simplex virus, type 1, and is the first oncolytic virus therapy to be approved for the treatment of advanced melanoma by the US FDA. T-VEC is attenuated by the deletion of the herpes neurovirulence viral genes and enhanced for immunogenicity by the deletion of the viral ICP47 gene. Immunogenicity is further supported by expression of the human granulocyte-macrophage colony-stimulating factor (GM-CSF) gene, which helps promote the priming of T cell responses. T-VEC demonstrated significant improvement in durable response rate, objective response rate, and progression-free survival in a randomized phase III clinical trial for patients with advanced melanoma. This review will discuss the optimal selection of patients for such treatment and describe how therapy is optimally delivered. We will also discuss future directions for oncolytic virus immunotherapy, which will likely include combination T-VEC clinical trials, expansion of T-VEC to other types of non-melanoma skin cancers, and renewed efforts at oncolytic virus drug development with other viruses.

Effective Combination of Innate and Adaptive Immunotherapeutic Approaches in a Mouse Melanoma Model

Most cancer immunotherapies include activation of either innate or adaptive immune responses. We hypothesized that the combined activation of both innate and adaptive immunity will result in better antitumor efficacy. We have previously shown the synergy of an agonistic anti-CD40 mAb (anti-CD40) and CpG-oligodeoxynucleotides in activating macrophages to induce tumor cell killing in mice. Separately, we have shown that a direct intratumoral injection of immunocytokine (IC), an anti-GD2 Ab linked to IL-2, can activate T and NK cells resulting in antitumor effects. We hypothesized that activation of macrophages with anti-CD40/CpG, and NK cells with IC, would cause innate tumor destruction, leading to increased presentation of tumor Ags and adaptive T cell activation; the latter could be further augmented by anti-CTLA-4 Ab to achieve tumor eradication and immunological memory. Using the mouse GD2⁺ B78 melanoma model, we show that anti-CD40/CpG treatment led to upregulation of T cell activation markers in draining lymph nodes. Anti-CD40/CpG + IC/anti-CTLA-4 synergistically induced regression of advanced s.c. tumors, resulting in cure of some mice and development of immunological memory against B78 and wild type B16 tumors. Although the antitumor effect of anti-CD40/CpG did not require T cells, the antitumor effect of IC/anti-CTLA-4 was dependent on T cells. The combined treatment with anti-CD40/CpG + IC/anti-CTLA-4 reduced T regulatory cells in the tumors and was effective against distant solid tumors and lung metastases. We suggest that a combination of anti-CD40/CpG and IC/anti-CTLA-4 should be developed for clinical testing as a potentially effective novel immunotherapy strategy.

Adaptive immunity programmes in breast cancer

The role of the immune system in shaping cancer development and patient prognosis has recently become an area of intense focus in industry and academia. Harnessing the adaptive arm of the immune system for tumour eradication has shown great promise in a variety of tumour types. Differences between tissues, however, necessitate a greater understanding of the adaptive immunity programmes that are active within each tumour type. In breast cancer, adaptive immune programmes play diverse roles depending on the cellular infiltration found in each tumour. Cytotoxic T lymphocytes and T helper type 1 cells can induce tumour eradication, whereas regulatory T cells and T helper type 2 cells are known to be involved in tumour-promoting immunosuppressive responses. Complicating these matters, heterogeneous expression of hormone receptors and growth factors in different tumours leads to disparate, patient-specific adaptive immune responses. Despite this non-conformity in adaptive immune behaviours, encouraging basic and clinical results have been observed that suggest a role for immunotherapeutic approaches in breast cancer. Here, we review the literature pertaining to the adaptive immune response in breast cancer, summarize the primary findings relating to the breast tumour's biology, and discuss potential clinical immunotherapies.

Combine and conquer: challenges for targeted therapy combinations in early phase trials

Our increasing understanding of cancer biology has led to the development of molecularly targeted anticancer drugs. The full potential of these agents has not, however, been realised, owing to the presence of de novo (intrinsic) resistance, often resulting from compensatory signalling pathways, or the development of acquired resistance in cancer cells via clonal evolution under the selective pressures of treatment. Combinations of targeted treatments can circumvent some mechanisms of resistance to yield a clinical benefit. We explore the challenges in identifying the best drug combinations and the best combination strategies, as well as the complexities of delivering these treatments to patients. Recognizing treatment-induced toxicity and the inability to use continuous pharmacodynamically effective doses of many targeted treatments necessitates creative intermittent scheduling. Serial tumour profiling and the use of parallel co-clinical trials can contribute to understanding mechanisms of resistance, and will guide the development of adaptive clinical trial designs that can accommodate hypothesis testing, in order to realize the full potential of combination therapies.

Immunomodulatory and Antitumor Effects of a Novel TLR7 Agonist Combined with Lapatinib

As new treatment approaches, both immunotherapy and targeted treatments have been used in the clinical treatment of cancers. These therapies are different from traditional surgery, chemotherapy and radiotherapy. Use of a combination of immunotherapy and targeted treatments may improve tumor clearance. We investigated the feasibility of combining tyrosine kinase inhibitors (TKIs, targeted drugs) and SZU-101 (a novel TLR7 agonist synthesized by our laboratory). Thirteen different TKIs were combined with or without SZU-101 and studied to determine their effects on immunocytes. On the basis of the distinctive results, lapatinib and sunitinib were selected for further tumor-inhibition investigation and determination of the underlying mechanism. Interestingly, we found lapatinib to work better with SZU-101, enhancing tumor clearance in vivo, without affecting the TLR7-NF-κB pathway activated by the TLR7 agonist in mouse spleen lymphocytes and bone marrow dendritic cells (BMDCs).

New chemical treatment options in second-line hepatocellular carcinoma: what to do when sorafenib fails?

INTRODUCTION

There have been no therapies available for patients who experience disease progression after sorafenib treatment. Regorafenib inhibits multiple kinases involved in tumor proliferation and neoangiogenesis, which has produced a survival benefit in hepatocellular carcinoma (HCC) after sorafenib failure. Other active candidate agents are c-Met inhibitors and immune checkpoint inhibitors. Areas covered: This paper presents an updated summary of the preclinical and clinical experience with regorafenib, c-Met inhibitors (tivantinib, cabozantinib and tepotinib), and a checkpoint inhibitor (nivolumab, pembrolizumab) in HCC. The reported data were obtained from abstracts of international conferences and journal articles published up to August 2016 and found in a PubMed search. Expert opinion: Based on favorable data from preclinical and clinical trials, regorafenib, c-Met inhibitor, and checkpoint inhibitors are promising agents for HCC after sorafenib failure. However, further efforts to maximize the survival benefit and minimize adverse events of these drugs in the treatment of HCC are still necessary. Additionally, searching for predictors of good responders could allow these new drugs to be applied in personalized treatments of HCC.

The Impact of Chemotherapy, Radiation and Epigenetic Modifiers in Cancer Cell Expression of Immune Inhibitory and Stimulatory Molecules and Anti-Tumor Efficacy

Genomic destabilizers, such as radiation and chemotherapy, and epigenetic modifiers are used for the treatment of cancer due to their apoptotic effects on the aberrant cells. However, these therapies may also induce widespread changes within the immune system and cancer cells, which may enable tumors to avoid immune surveillance and escape from host anti-tumor immunity. Genomic destabilizers can induce immunogenic death of tumor cells, but also induce upregulation of immune inhibitory ligands on drug-resistant cells, resulting in tumor progression. While administration of immunomodulatory antibodies that block the interactions between inhibitory receptors on immune cells and their ligands on tumor cells can mediate cancer regression in a subset of treated patients, it is crucial to understand how genomic destabilizers alter the immune system and malignant cells, including which inhibitory molecules, receptors and/or ligands are upregulated in response to genotoxic stress. Knowledge gained in this area will aid in the rational design of trials that combine genomic destabilizers, epigenetic modifiers and immunotherapeutic agents that may be synergized to improve clinical responses and prevent tumor escape from the immune system. Our review article describes the impact genomic destabilizers, such as radiation and chemotherapy, and epigenetic modifiers have on anti-tumor immunity and the tumor microenvironment. Although genomic destabilizers cause DNA damage on cancer cells, these therapies can also have diverse effects on the immune system, promote immunogenic cell death or survival and alter the cancer cell expression of immune inhibitor molecules.

Systemic therapy for bladder cancer finally comes into a new age

Systemic therapy for bladder cancer, both localized muscle-invasive disease and metastatic disease, has seen minimal progress over the past two decades. Current approaches rely upon cytotoxic chemotherapy combinations aimed at increasing cure rates or achieving palliation and disease control, but these regimens are fraught with short- and long-term toxicities and outcomes remain suboptimal. The emergence of systemic immunotherapies that can provide durable remissions in subsets of patients with other malignancies has the potential to transform the field, and early phase trials have begun to demonstrate activity in some patients with metastatic bladder cancer. In this article, we review the current state of systemic therapy for bladder cancer and discuss the current literature and ongoing trials utilizing various immunotherapies.

Combining Type I Interferons and 5-Aza-2'-Deoxycitidine to Improve Anti-Tumor Response against Melanoma

Resistance to IFN-I-induced antineoplastic effects has been reported in many tumors and arises, in part, from epigenetic silencing of IFN-stimulated genes by DNA methylation. We hypothesized that restoration of IFN-stimulated genes by co-administration of the demethylating drug 5-aza-2'-deoxycitidine (decitabine [DAC]) may enhance the susceptibility to IFN-I-mediated antitumoral effects in melanoma. We show that combined administration of IFN-I and DAC significantly inhibits the growth of murine and human melanoma cells, both in vitro and in vivo. Compared with controls, DAC/IFN-I-treated melanoma cells exhibited reduced cell growth, augmented apoptosis, and diminished migration. Moreover, IFN-I and DAC synergized to suppress the growth of three-dimensional human melanoma spheroids, altering tumor architecture. These direct antitumor effects correlated with induction of the IFN-stimulated gene Mx1. In vivo, DAC/IFN-I significantly reduced melanoma growth via stimulation of adaptive immunity, promoting tumor-infiltrating CD8⁺ T cells while inhibiting the homing of immunosuppressive CD11b⁺ myeloid cells and regulatory T cells. Accordingly, exposure of human melanoma cells to DAC/IFN-I induced the recruitment of immune cells toward the tumor in a Matrigel (Corning Life Sciences, Kennebunkport, ME)-based microfluidic device. Our findings underscore a beneficial effect of DAC plus IFN-I combined treatment against melanoma through both direct and immune-mediated anti-tumor effects.

Acute skin reaction suggestive of pembrolizumab-induced radiosensitization

The combination of localized radiotherapy and immune checkpoint inhibitors represents a promising therapeutic strategy for various cancers, including metastatic melanoma. Radiation therapy may enhance tumor antigen presentation and cytokine release, which may optimize the systemic antitumor immune response induced by these immunotherapeutic antibodies, with a potential delayed abscopal effect. However, clinical experience of using immune checkpoint inhibitors with concurrent radiotherapy remains scarce. We report here for the first time a case suggestive of acute skin radiosensitization induced by pembrolizumab, with a suggestive time relationship between the completion of ionizing radiation, drug administration, and rapid onset of the skin reaction. This suggests that radiation therapy may also interact rapidly with anti-programmed-death 1 antibodies. Therefore, caution should be exercised when prescribing this combination therapy in advanced cancers.

Clinical development of talimogene laherparepvec (T-VEC): a modified herpes simplex virus type-1-derived oncolytic immunotherapy

Tumor immunotherapy is emerging as a promising new treatment option for patients with cancer. T-VEC is an intralesional oncolytic virus therapy based on a modified herpes simplex virus type-1. T-VEC selectively targets tumor cells, causing regression in injected lesions and inducing immunologic responses that mediate regression at uninjected/distant sites. In a randomized phase III trial, T-VEC met its primary endpoint of improving the durable response rate vs granulocyte-macrophage colony-stimulating factor in patients with unresectable melanoma. Responses were observed in injected and uninjected regional and visceral lesions. Exploratory analyses suggested survival differences in favor of T-VEC in patients with untreated or stage IIIB/IIIC/IVM1a disease. T-VEC was generally well tolerated, the most common adverse events being flu-like symptoms. Here, we overview recent advances in cancer immunotherapy, focusing on the clinical development of T-VEC, from first-in-human studies and studies in other cancer types, to ongoing combination trials with checkpoint inhibitors.

Trial Watch: Immunotherapy plus radiation therapy for oncological indications

Malignant cells succumbing to some forms of radiation therapy are particularly immunogenic and hence can initiate a therapeutically relevant adaptive immune response. This reflects the intrinsic antigenicity of malignant cells (which often synthesize a high number of potentially reactive neo-antigens) coupled with the ability of radiation therapy to boost the adjuvanticity of cell death as it stimulates the release of endogenous adjuvants from dying cells. Thus, radiation therapy has been intensively investigated for its capacity to improve the therapeutic profile of several anticancer immunotherapies, including (but not limited to) checkpoint blockers, anticancer vaccines, oncolytic viruses, Toll-like receptor (TLR) agonists, cytokines, and several small molecules with immunostimulatory effects. Here, we summarize recent preclinical and clinical advances in this field of investigation.

Immuno-oncology combinations: raising the tail of the survival curve

There have been exponential gains in immuno-oncology in recent times through the development of immune checkpoint inhibitors. Already approved by the U.S. Food and Drug Administration for advanced melanoma and non-small cell lung cancer, immune checkpoint inhibitors also appear to have significant antitumor activity in multiple other tumor types. An exciting component of immunotherapy is the durability of antitumor responses observed, with some patients achieving disease control for many years. Nevertheless, not all patients benefit, and efforts should thus now focus on improving the efficacy of immunotherapy through the use of combination approaches and predictive biomarkers of response and resistance. There are multiple potential rational combinations using an immunotherapy backbone, including existing treatments such as radiotherapy, chemotherapy or molecularly targeted agents, as well as other immunotherapeutics. The aim of such antitumor strategies will be to raise the tail on the survival curve by increasing the number of long term survivors, while managing any additive or synergistic toxicities that may arise with immunotherapy combinations. Rational trial designs based on a clear understanding of tumor biology and drug pharmacology remain paramount. This article reviews the biology underpinning immuno-oncology, discusses existing and novel immunotherapeutic combinations currently in development, the challenges of predictive biomarkers of response and resistance and the impact of immuno-oncology on early phase clinical trial design.

Immune checkpoint blockade: Releasing the brake towards hematological malignancies

Tumor cells utilize co-inhibitory molecules to avoid host immune destruction. Checkpoint blockade has emerged as a promising approach to treat cancer by restoring T cell effector function and breaking a tumor permissive microenvironment. Patients with hematological malignancies often have immune dysregulation, thus the role of checkpoint blockade in treatment of these neoplasms is particularly intriguing. In early trials, antibodies targeting cytotoxic T lymphocyte antigen 4 (CTLA-4) or the programmed death 1 (PD-1) signaling pathway have displayed significant efficacy with minimal toxicity in patients with relapsed and refractory hematological neoplasms. In this review, we provide evidence of dysregulation of CTLA-4 and PD-1/PD-Ls in the context of several major types of hematological neoplasms and summarize relevant clinical practice points for checkpoint blockade. The preclinical rationale and preliminary clinical data of potential combination approaches designed to optimize checkpoint antagonists are well presented.

Leveraging immunotherapy for the treatment of gynecologic cancers in the era of precision medicine

During the past decade significant progress in the understanding of stimulatory and inhibitory signaling pathways in immune cells has reinvigorated the field of immuno-oncology. In this review we outline the current immunotherapy based approaches for the treatment of gynecological cancers, and focus on the emerging clinical data on immune checkpoint inhibitors, adoptive cell therapies, and vaccines. It is anticipated that in the coming years biomarker-guided clinical trials, will provide for a better understanding of the mechanisms of response and resistance to immunotherapy, and guide combination treatment strategies that will extend the benefit from immunotherapy to patients with gynecologic cancers.

A paradigm shift: Cancer therapy with peptide-based B-cell epitopes and peptide immunotherapeutics targeting multiple solid tumor types: Emerging concepts and validation of combination immunotherapy

There is a recognizable and urgent need to speed the development and application of novel, more efficacious anti-cancer vaccine therapies that inhibit tumor progression and prevent acquisition of tumor resistance. We have created and established a portfolio of validated peptide epitopes against multiple receptor tyrosine kinases and we have identified the most biologically effective combinations of EGFR (HER-1), HER-2, HER-3, VEGF and IGF-1R peptide vaccines/mimics to selectively inhibit multiple receptors and signaling pathways. The strategy is based on the use of chimeric conformational B-cell epitope peptides incorporating "promiscuous" T-cell epitopes that afford the possibility of generating an enduring immune response, eliciting protein-reactive high-affinity anti-peptide antibodies as potential vaccines and peptide mimics that act as antagonists to receptor signaling that drive cancer metastasis. In this review we will summarize our ongoing studies based on the development of combinatorial immunotherapeutic strategies that act synergistically to enhance immune-mediated tumor killing aimed at addressing mechanisms of tumor resistance for several tumor types.

Viro-immune therapy: A new strategy for treatment of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an almost uniformly lethal disease with less than 5% survival at five years. This is largely due to metastatic disease, which is already present in the majority of patients when diagnosed. Even when the primary cancer can be removed by radical surgery, local recurrence occurs within one year in 50%-80% of cases. Therefore, it is imperative to develop new approaches for the treatment of advanced cancer and the prevention of recurrence after surgery. Tumour-targeted oncolytic viruses (TOVs) have become an attractive therapeutic agent as TOVs can kill cancer cells through multiple mechanisms of action, especially via virus-induced engagement of the immune response specifically against tumour cells. To attack tumour cells effectively, tumour-specific T cells need to overcome negative regulatory signals that suppress their activation or that induce tolerance programmes such as anergy or exhaustion in the tumour microenvironment. In this regard, the recent breakthrough in immunotherapy achieved with immune checkpoint blockade agents, such as anti-cytotoxic T-lymphocyte-associate protein 4, programmed death 1 (PD-1) or PD-L1 antibodies, has demonstrated the possibility of relieving immune suppression in PDAC. Therefore, the combination of oncolytic virotherapy and immune checkpoint blockade agents may synergistically function to enhance the antitumour response, lending the opportunity to be the future for treatment of pancreatic cancer.