Immune checkpoint blockade immunotherapy to activate anti-tumour T-cell immunity

Genomic correlates of response to immune checkpoint therapies in clear cell renal cell carcinoma

Immune checkpoint inhibitors targeting the programmed cell death 1 receptor (PD-1) improve survival in a subset of patients with clear cell renal cell carcinoma (ccRCC). To identify genomic alterations in ccRCC that correlate with response to anti-PD-1 monotherapy, we performed whole-exome sequencing of metastatic ccRCC from 35 patients. We found that clinical benefit was associated with loss-of-function mutations in the PBRM1 gene (P = 0.012), which encodes a subunit of the PBAF switch-sucrose nonfermentable (SWI/SNF) chromatin remodeling complex. We confirmed this finding in an independent validation cohort of 63 ccRCC patients treated with PD-1 or PD-L1 (PD-1 ligand) blockade therapy alone or in combination with anti-CTLA-4 (cytotoxic T lymphocyte-associated protein 4) therapies (P = 0.0071). Gene-expression analysis of PBAF-deficient ccRCC cell lines and PBRM1-deficient tumors revealed altered transcriptional output in JAK-STAT (Janus kinase-signal transducers and activators of transcription), hypoxia, and immune signaling pathways. PBRM1 loss in ccRCC may alter global tumor-cell expression profiles to influence responsiveness to immune checkpoint therapy.

Identification of Shared Molecular Signatures Indicate the Susceptibility of Endometriosis to Multiple Sclerosis

Women with endometriosis (EMS) appear to be at a higher risk of developing other autoimmune diseases predominantly multiple sclerosis (MS). Though EMS and MS are evidently diverse in their phenotype, they are linked by a common autoimmune condition or immunodeficiency which could play a role in the expansion of endometriosis and possibly increase the risk of developing MS in women with EMS. However, the common molecular links connecting EMS with MS are still unclear. We conducted a meta-analysis of microarray experiments focused on EMS and MS with their respective controls. The GEO2R web application discovered a total of 711 and 1516 genes that are differentially expressed across the experimental conditions in EMS and MS, respectively with 129 shared DEGs between them. The functional enrichment analysis of DEGs predicts the shared gene expression signatures as well as the overlapping biological processes likely to infer the co-occurrence of EMS with MS. Network based meta-analysis unveiled six interaction networks/crosstalks through overlapping edges between commonly dysregulated pathways of EMS and MS. The PTPN1, ERBB3, and CDH1 were observed to be the highly ranked hub genes connected with disease-related genes of both EMS and MS. Androgen receptor (AR) and nuclear factor-kB p65 (RelA) were observed to be the most enriched transcription factor in the upstream of shared down-regulated and up-regulated genes, respectively. The two disease sample sets compared through crosstalk interactions between shared pathways revealed commonly up- and down-regulated expressions of 10 immunomodulatory proteins as probable linkers between EMS and MS. This study pinpoints the number of shared genes, pathways, protein kinases, and upstream regulators that may help in the development of biomarkers for diagnosis of MS and endometriosis at the same time through improved understanding of shared molecular signatures and crosstalk.

PD-L1 up-regulation in melanoma increases disease aggressiveness and is mediated through miR-17-5p

PD-L1 is expressed by a subset of patients with metastatic melanoma (MM) with an unfavorable outcome. Its expression is increased in cells resistant to BRAF or MEK inhibitors (BRAFi or MEKi). However, the function and regulation of expression of PD-L1 remain incompletely understood.

After generating BRAFi- and MEKi-resistant cell lines, we observed marked up-regulation of PD-L1 expression. These cells were characterized by a common gene expression profile with up-regulation of genes involved in cell movement. Consistently, in vitro they showed significantly increased invasive properties. This phenotype was controlled in part by PD-L1, as determined after silencing the molecule. Up-regulation of PD-L1 was due to post-transcriptional events controlled by miR-17-5p, which showed an inverse correlation with PD-L1 mRNA. Direct binding between miR-17-5p and the 3’-UTR of PD-L1 mRNA was demonstrated using luciferase reporter assays.

In a cohort of 80 BRAF-mutated MM patients treated with BRAFi or MEKi, constitutive expression of PD-L1 in the absence of immune infiltrate, defined the patient subset with the worst prognosis. Furthermore, PD-L1 expression increased in tissue biopsies after the metastatic lesions became resistant to BRAFi or MEKi. Lastly, plasmatic miR-17-5p levels were higher in patients with PD-L1⁺ than PD-L1^- lesions.

In conclusion, our findings indicate that PD-L1 expression induces a more aggressive behavior in melanoma cells. We also show that PD-L1 up-regulation in BRAFi or MEKi-resistant cells is partly due to post-transcriptional mechanisms that involve miR-17-5p, suggesting that miR-17-5p may be used as a marker of PD-L1 expression by metastatic lesions and ultimately a predictor of responses to BRAFi or MEKi.

Rationale for neoadjuvant immunotherapy in head and neck squamous cell carcinoma

The clinical benefit of immunotherapy in recurrent, metastatic head and neck squamous cell carcinoma has fueled interest in revisiting neoadjuvant approaches to complement definitive treatment. Neoadjuvant strategies incorporating immune checkpoint inhibitors and other novel immune-based therapies in head and neck cancer are reviewed here, with particular attention paid to the rationale for these approaches from both a clinical and biologic discovery standpoint. The potential benefits of neoadjuvant immunotherapy include reduction of extent of surgery and the intensity of adjuvant therapy by tumor downstaging, reduction of the risk of distant metastatic spread by early introduction of systemic therapy, conversion of unresectable to resectable disease, and early evaluation of biomarkers of tumor response. We await early trial results utilizing these approaches to confirm both safety and initial efficacy in head and neck cancer.

The immune checkpoint molecule V-set Ig domain-containing 4 is an independent prognostic factor for multiple myeloma

Multiple myeloma (MM) remains as an incurable disease, despite recent substantial improvements in treatment. Therefore, development of novel biomarkers for risk stratification and new therapeutic targets are imperative. One of the emerging treatments for MM is the immune checkpoint blockades. V-set Ig domain-containing 4 (VSIG4) is a lately studied B7-related immune checkpoint modulator. We assessed the VSIG4 expression in patients with MM and its prognostic impact. We analyzed 81 bone marrow and 66 extramedullary biopsy samples of MM patients using immunohistochemistry. VSIG4 mRNA expression data from the Multiple Myeloma Genomics Portal (MMGP) were analyzed to validate our results. The overall survival (OS) of the high VSIG4 expression group was significantly poorer than that of the low VSIG4 expression group (p = 0.046). VSIG4 expression was remained statistically significant after adjustment for revised international staging system (rISS) and Mayo stratification algorithm (mSMART) risk classification, respectively (p = 0.019 and 0.017). Corroborating results were also observed on analyses of VSIG4 expression in patients with extramedullary MM and external data from the MMGP. Our results suggest that VSIG4 expression in MM is an independent indicator of poor prognosis, implying a possible therapeutic target for immunotherapy for MM.

Tumor-derived vaccines containing CD200 inhibit immune activation: implications for immunotherapy

There are over 400 ongoing clinical trials using tumor-derived vaccines. This approach is especially attractive for many types of brain tumors, including glioblastoma, yet so far the clinical response is highly variable. One contributor to poor response is CD200, which acts as a checkpoint blockade, inducing immune tolerance. We demonstrate that, in response to vaccination, glioma-derived CD200 suppresses the anti-tumor immune response. In contrast, a CD200 peptide inhibitor that activates antigen-presenting cells overcomes immune tolerance. The addition of the CD200 inhibitor significantly increased leukocyte infiltration into the vaccine site, cytokine and chemokine production, and cytolytic activity. Our data therefore suggest that CD200 suppresses the immune system's response to vaccines, and that blocking CD200 could improve the efficacy of cancer immunotherapy.

Targeted therapies in breast cancer: New challenges to fight against resistance

Breast cancer is the most common type of cancer found in women and today represents a significant challenge to public health. With the latest breakthroughs in molecular biology and immunotherapy, very specific targeted therapies have been tailored to the specific pathophysiology of different types of breast cancers. These recent developments have contributed to a more efficient and specific treatment protocol in breast cancer patients. However, the main challenge to be further investigated still remains the emergence of therapeutic resistance mechanisms, which develop soon after the onset of therapy and need urgent attention and further elucidation. What are the recent emerging molecular resistance mechanisms in breast cancer targeted therapy and what are the best strategies to apply in order to circumvent this important obstacle? The main scope of this review is to provide a thorough update of recent developments in the field and discuss future prospects for preventing resistance mechanisms in the quest to increase overall survival of patients suffering from the disease.

Coordinating antigen cytosolic delivery and danger signaling to program potent cross-priming by micelle-based nanovaccine

Although re-activating cytotoxic T-cell (CTLs) response inside tumor tissues by checkpoint blockade has demonstrated great success in tumor immunotherapy, active induction of efficient endogenous CTL response by therapeutic vaccines has been largely hampered by inefficient cytosolic delivery of antigens and coordinated activation of dendritic cells (DCs) in lymph nodes. Here we show that polyethylene glycol-phosphatidylethanolamine (PEG-PE) micelles transform soluble peptides into α-helix to enable their efficient cytosolic delivery. The same PEG-PE micelles also serve as chaperon of TLR4 signaling to coordinate its adjuvant effect on the same DCs. Furthermore, these nanovaccines effectively target lymph node DCs. Thus, PEG-PE micelle vaccines program at multiple key aspects for inducing strong CTL responses and build up a foundation for combinational tumor therapy.

Immunotherapy of head and neck cancer: Emerging clinical trials from a National Cancer Institute Head and Neck Cancer Steering Committee Planning Meeting

Recent advances have permitted successful therapeutic targeting of the immune system in head and neck squamous cell carcinoma (HNSCC). These new immunotherapeutic targets and agents are being rapidly adopted by the oncologic community and hold considerable promise. The National Cancer Institute sponsored a Clinical Trials Planning Meeting to address the issue of how to further investigate the use of immunotherapy in patients with HNSCC. The goals of the meeting were to consider phase 2 or 3 trial designs primarily in 3 different patient populations: those with previously untreated, human papillomavirus-initiated oropharyngeal cancers; those with previously untreated, human papillomavirus-negative HNSCC; and those with recurrent/metastatic HNSCC. In addition, a separate committee was formed to develop integrative biomarkers for the clinical trials. The meeting started with an overview of key immune components and principles related to HNSCC, including immunosurveillance and immune escape. Four clinical trial concepts were developed at the meeting integrating different immunotherapies with existing standards of care. These designs were presented for implementation by the head and neck committees of the National Cancer Institute-funded National Clinical Trials Network. This article summarizes the proceedings of this Clinical Trials Planning Meeting, the purpose of which was to facilitate the rigorous development and design of randomized phase 2 and 3 immunotherapeutic trials in patients with HNSCC. Although reviews usually are published immediately after the meeting is held, this report is unique because there are now tangible clinical trial designs that have been funded and put into practice and the studies are being activated to accrual. Cancer 2017;123:1259-1271. © 2016 American Cancer Society.

Immune checkpoint dysfunction in large and medium vessel vasculitis

Giant cell arteritis (GCA) is a granulomatous vasculitis of the aorta and its medium-sized branch vessels. CD4 T cells, macrophages, and dendritic cells (DCs) build granulomatous infiltrates that injure the vessel wall and elicit a maladaptive response to injury. Pathological consequences include fragmentation of elastic membranes, destruction of the medial layer, microvascular neoangiogenesis, massive outgrowth of myofibroblasts, and lumen-occlusive intimal hyperplasia. Antigens have been suspected to drive the local activation of vasculitogenic CD4 T cells, but recent data have suggested a more generalized defect in the threshold setting of such T cells, rendering them hyperreactive. Under physiological conditions, immune checkpoints provide negative signals to curb T cell activation and prevent inflammation-associated tissue destruction. This protective mechanism is disrupted in GCA. Vessel wall DCs fail to express the immunoinhibitory ligand programmed cell death ligand-1, leaving lesional T cells unchecked. Consequently, programmed cell death protein-1-positive CD4 T cells can enter the immunoprivileged vessel wall, where they produce a broad spectrum of inflammatory cytokines (interferon-γ, IL-17, and IL-21) and have a direct role in driving intimal hyperplasia and intramural neoangiogenesis. The deficiency of the programmed cell death protein-1 immune checkpoint in GCA, promoting unopposed T cell immunity, contrasts with checkpoint hyperactivity in cancer patients in whom excessive programmed cell death ligand-1 expression paralyzes the function of antitumor T cells. Excessive checkpoint activity is the principle underlying cancer-immune evasion and is therapeutically targeted by immunotherapy with checkpoint inhibitors. Such checkpoint inhibitors, which unleash anticancer T cells and induce immune-related toxicity, may lead to drug-induced vasculitis.

Defining an inflamed tumor immunophenotype in recurrent, metastatic squamous cell carcinoma of the head and neck

OBJECTIVES

Immune checkpoint inhibitors have demonstrated clinical benefit in recurrent, metastatic (R/M) squamous cell carcinoma of the head and neck (SSCHN), but lacking are biomarkers that predict response. We sought to define an inflamed tumor immunophenotype in this R/M SCCHN population and correlate immune metrics with clinical parameters and survival.

METHODS

Tumor samples were prospectively acquired from 34 patients to perform multiparametric flow cytometry and multidimensional clustering analysis integrated with next-generation sequencing data, clinical parameters and outcomes.

RESULTS

We identified an inflamed subgroup of tumors with prominent CD8+ T cell infiltrates and high PD-1/TIM3 co-expression independent of clinical variables, with improved survival compared with a non-inflamed subgroup (median overall survival 84.0 vs. 13.0months, p=0.004). The non-inflamed subgroup demonstrated low CD8+ T cells, low PD-1/TIM3 co-expression, and higher T_regs. Overall non-synonymous mutational burden did not correlate with response to PD-1 blockade in a subset of patients.

CONCLUSION

R/M SCCHN patients with an inflamed tumor immunophenotype demonstrate improved survival. Further prospective studies are needed to validate these findings and explore the use of immunophenotype to guide patient selection for immunotherapeutic approaches.

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.

PD-L1 Is Not Constitutively Expressed on Tasmanian Devil Facial Tumor Cells but Is Strongly Upregulated in Response to IFN-γ and Can Be Expressed in the Tumor Microenvironment

The devil facial tumor disease (DFTD) is caused by clonal transmissible cancers that have led to a catastrophic decline in the wild Tasmanian devil (Sarcophilus harrisii) population. The first transmissible tumor, now termed devil facial tumor 1 (DFT1), was first discovered in 1996 and has been continually transmitted to new hosts for at least 20 years. In 2015, a second transmissible cancer [devil facial tumor 2 (DFT2)] was discovered in wild devils, and the DFT2 is genetically distinct and independent from the DFT1. Despite the estimated 136,559 base pair substitutions and 14,647 insertions/deletions in the DFT1 genome as compared to two normal devil reference genomes, the allograft tumors are not rejected by the host immune system. Additionally, genome sequencing of two sub-strains of DFT1 detected greater than 15,000 single-base substitutions that were found in only one of the DFT1 sub-strains, demonstrating the transmissible tumors are evolving and that generation of neoantigens is likely ongoing. Recent evidence in human clinical trials suggests that blocking PD-1:PD-L1 interactions promotes antitumor immune responses and is most effective in cancers with a high number of mutations. We hypothesized that DFTD cells could exploit the PD-1:PD-L1 inhibitory pathway to evade antitumor immune responses. We developed recombinant proteins and monoclonal antibodies (mAbs) to provide the first demonstration that PD-1 binds to both PD-L1 and PD-L2 in a non-placental mammal and show that PD-L1 is upregulated in DFTD cells in response to IFN-γ. Immunohistochemistry showed that PD-L1 is rarely expressed in primary tumor masses, but low numbers of PD-L1+ non-tumor cells were detected in the microenvironment of several metastatic tumors. Importantly, in vitro testing suggests that PD-1 binding to PD-L1 and PD-L2 can be blocked by mAbs, which could be critical to understanding how the DFT allografts evade the immune system.

Programmed cell death 1 correlates with the occurrence and development of MG63 osteosarcoma

The aim of the present study was to investigate the effect of programmed cell death 1 (PD-1) on osteosarcoma (OD) stem cells and T cells, and to determine their correlation. OS stem cells were sorted and identified from OS MG63 cells. Flow cytometry was used to detect the PD-1 expression of the OS tumor stem cell membrane surface. The expression of PD-1 mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). MTT was used to detect the effect of PD-1 signals on T-cell proliferation. The results indicated that the cancer cells (cultured in DMEM medium containing 10% fetal bovine serum) exhibited clear proliferation within 1 week of cell culture, which showed their strong proliferation and aggressive ability. The formation of tumor cell spheres was dependent on the support of serum nutrition. The proliferation of MG63 cells in the serum culture medium was significantly higher than the number of OS cell spheres in serum-free suspension culture (P<0.05). Pluripotent stem cells in cancer cell spheres exhibited significantly higher cluster of differentiation 133 expression compared with the MG63 cells. The PD-1 expression levels of the cancer cell spheres was significantly increased compared with the MG63 cells, which is consistent with the results of the RT-PCR. In conclusion, the MG63 cell line possesses the features of OS stem cells. The MG63 cell line can express the certain cancer-associated cell markers. The expression of PD-1 in spheres was also increased significantly compared to the MG63 cells, which can reduce the immune function of patients and may be closely associated with the occurrence and development of tumors.

Programmed death-ligand 1 expression in rectal cancer

Background

Colorectal cancer (CRC) is the fourth most common cause of death worldwide. Approximately 30 % of all CRC occurs in the rectum. Improvements in survival rates were achieved thanks to multimodal therapy, combining surgery and chemoradiation. Nevertheless, the prognosis of patients suffering from rectal cancer (RC) remains poor. Programmed cell death protein 1 (PD-1) and its ligand programmed death ligand 1 (PD-L1) regulate tumor immune response. The aim of this study was to analyze the expression of PD-L1 in RC pre- and post-neoadjuvant therapy and evaluate PD-L1 as a biomarker and potential target for therapy.

Methods

In all, 29 patients with RC treated at the Medical University Vienna who received preoperative chemoradiation were retrospectively enrolled in this study. Expression of PD-L1 was investigated by immunohistochemistry with two different anti-PD-L1 antibodies.

Results

No PD-L1 expression on cancer cells could be observed in all 29 cases in the specimens before chemoradiation as well as in the surgical specimens after neoadjuvant therapy. In one of the two staining methods performed, five (17.24 %) post-chemoradiation cases showed faint lymphohistiocytic staining.

Conclusion

No expression of PD-L1 in RC cells before and after chemoradiation was found in our collective of 29 patients. Further investigations to evaluate the role of PD-L1 as a potential therapeutic target in RC are urgently needed.

Trends and advances in tumor immunology and lung cancer immunotherapy

Among several types of tumor, lung cancer is considered one of the most fatal and still the main cause of cancer-related deaths. Although chemotherapeutic agents can improve survival and quality of life compared with symptomatic treatment, cancers usually still progress after chemotherapy and are often aggravated by serious side effects. In the last few years there has been a growing interest in immunotherapy for lung cancer based on promising preliminary results in achieving meaningful and durable treatments responses with minimal manageable toxicity. This article is divided into two parts, the first part discusses the role of human immune system in controlling and eradicating cancer and the mechanisms of immune response evasion by tumor. The second part reviews the recent progress made in immunotherapy for lung cancer with results from trials evaluating therapeutic vaccines in addition to immune checkpoint blockade, specifically cytotoxic T lymphocyte associated protein 4, programmed death receptor 1 pathway, using monoclonal antibodies.

Comprehensive molecular profiling of the B7 family of immune-regulatory ligands in breast cancer

The B7 gene family has crucial roles in the regulation of adaptive cellular immunity. In cancer, deregulation of co-inhibitory B7 molecules is associated with reduced antitumor immunity and cancer immune evasion. FDA approval of cancer immunotherapy antibodies against cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed cell death-1 (PD-1)-both ligands of the B7 family-demonstrate the impact of these checkpoint regulators in cancer. Using data from cBioPortal, we performed comprehensive molecular profiling of the 10 currently known B7 family proteins in 105 different cancers. B7 family members were amplified in breast cancer: with B7 mRNA levels upregulated in a cohort of 1,098 patients with all types of breast cancer and in 82 patients with triple-negative breast cancer. Promoter methylation analysis indicated an epigenetic basis for deregulation of certain B7 family genes in breast cancer. Moreover, patients with B7-H6 genomic alterations had significantly worse overall survival, and certain clinical attributes were associated with B7-H6 expression, which indicates that B7-H6 may be a potential target for breast cancer immunotherapy. Finally, using network analysis (based on data from cBioportal), we identified BTLA, MARCH8, PLSCR1 and SMAD3 as potentially involved in T cell signaling under regulation of B7 family proteins.

Extracellular vesicles released by CD40/IL-4-stimulated CLL cells confer altered functional properties to CD4+ T cells

The complex interplay between cancer cells, stromal cells, and immune cells in the tumor microenvironment (TME) regulates tumorigenesis and provides emerging targets for immunotherapies. Crosstalk between CD4(+) T cells and proliferating chronic lymphocytic leukemia (CLL) tumor B cells occurs within lymphoid tissue pseudofollicles, and investigating these interactions is essential to understand both disease pathogenesis and the effects of immunotherapy. Tumor-derived extracellular vesicle (EV) shedding is emerging as an important mode of intercellular communication in the TME. In order to characterize tumor EVs released in response to T-cell-derived TME signals, we performed microRNA (miRNA [miR]) profiling of EVs released from CLL cells stimulated with CD40 and interleukin-4 (IL-4). Our results reveal an enrichment of specific cellular miRNAs including miR-363 within EVs derived from CD40/IL-4-stimulated CLL cells compared with parental cell miRNA content and control EVs from unstimulated CLL cells. We demonstrate that autologous patient CD4(+) T cells internalize CLL-EVs containing miR-363 that targets the immunomodulatory molecule CD69. We further reveal that autologous CD4(+) T cells that are exposed to EVs from CD40/IL-4-stimulated CLL cells exhibit enhanced migration, immunological synapse signaling, and interactions with tumor cells. Knockdown of miR-363 in CLL cells prior to CD40/IL-4 stimulation prevented the ability of CLL-EVs to induce increased synapse signaling and confer altered functional properties to CD4(+) T cells. Taken together, these data reveal a novel role for CLL-EVs in modifying T-cell function that highlights unanticipated complexity of intercellular communication that may have implications for bidirectional CD4(+) T-cell:tumor interactions within the TME.

Regulation of Natural Killer Cell Function by STAT3

Natural killer (NK) cells, key members of a distinct hematopoietic lineage, innate lymphoid cells, are not only critical effectors that mediate cytotoxicity toward tumor and virally infected cells but also regulate inflammation, antigen presentation, and the adaptive immune response. It has been shown that NK cells can regulate the development and activation of many other components of the immune response, such as dendritic cells, which in turn, modulate the function of NK cells in multiple synergistic feed back loops driven by cell–cell contact, and the secretion of cytokines and chemokines that control effector function and migration of cells to sites of immune activation. The signal transducer and activator of transcription (STAT)-3 is involved in driving almost all of the pathways that control NK cytolytic activity as well as the reciprocal regulatory interactions between NK cells and other components of the immune system. In the context of tumor immunology, NK cells are a first line of defense that eliminates pre-cancerous and transformed cells early in the process of carcinogenesis, through a mechanism of “immune surveillance.” Even after tumors become established, NK cells are critical components of anticancer immunity: dysfunctional NK cells are often found in the peripheral blood of cancer patients, and the lack of NK cells in the tumor microenvironment often correlates to poor prognosis. The pathways and soluble factors activated in tumor-associated NK cells, cancer cells, and regulatory myeloid cells, which determine the outcome of cancer immunity, are all critically regulated by STAT3. Using the tumor microenvironment as a paradigm, we present here an overview of the research that has revealed fundamental mechanisms through which STAT3 regulates all aspects of NK cell biology, including NK development, activation, target cell killing, and fine tuning of the innate and adaptive immune responses.

Changing the paradigm: the potential for targeted therapy in laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) remains a highly morbid and fatal disease. Historically, it has been a model example for organ preservation and treatment stratification paradigms. Unfortunately, survival for LSCC has stagnated over the past few decades. As the era of next-generation sequencing and personalized treatment for cancer approaches, LSCC may be an ideal disease for consideration of further treatment stratification and personalization. Here, we will discuss the important history of LSCC as a model system for organ preservation, unique and potentially targetable genetic signatures of LSCC, and methods for bringing stratified, personalized treatment strategies to the 21(st) century.

Immunology and Immunotherapy of Head and Neck Cancer

The immune system plays a key role in the development, establishment, and progression of head and neck squamous cell carcinoma (HNSCC). A greater understanding of the dysregulation and evasion of the immune system in the evolution and progression of HNSCC provides the basis for improved therapies and outcomes for patients. HNSCC cells evade the host immune system through manipulation of their own immunogenicity, production of immunosuppressive mediators, and promotion of immunomodulatory cell types. Through the tumor's influence on the microenvironment, the immune system can be exploited to promote metastasis, angiogenesis, and growth. This article provides a brief overview of key components of the immune infiltrating cells in the tumor microenvironment, reviewing immunological principles related to head and neck cancer, including the concept of cancer immunosurveillance and immune escape. Current immunotherapeutic strategies and emerging results from ongoing clinical trials are presented.

Increase of PD-L1 expressing B-precursor ALL cells in a patient resistant to the CD19/CD3-bispecific T cell engager antibody blinatumomab

The bispecific T cell engager blinatumomab has shown encouraging clinical activity in B-precursor acute lymphoblastic leukemia (ALL). However, about half of relapsed/refractory patients do not respond to therapy. Here, we present the case of a 32-year-old male patient with refractory B-precursor ALL who was resistant to treatment with blinatumomab. Bone marrow immunohistochemistry revealed T cell infiltrates and an increase in programmed death-ligand 1 (PD-L1)-positive ALL cells as a potential immune escape mechanism. We were able to recapitulate the clinical observation in vitro by showing that blinatumomab was not able to mediate cytotoxicity of CD19-positive ALL cells using autologous T cells. In contrast, the addition of healthy donor T cells led to lysis of ALL cells.

These results strongly encourage further systematic evaluation of checkpoint molecules in cases of blinatumomab treatment failure and might highlight a possible mechanism to overcome resistance to this otherwise highly effective treatment.

Immune Checkpoint inhibitors: An introduction to the next-generation cancer immunotherapy

Activating the immune system to eliminate cancer cells and produce clinically relevant responses has been a long-standing goal of cancer research. Most promising therapeutic approaches to activating antitumor immunity include immune checkpoint inhibitors. Immune checkpoints are numerous inhibitory pathways hardwired in the immune system. They are critical for maintaining self-tolerance and modulating the duration and amplitude of physiological immune responses in peripheral tissues to minimize collateral tissue damage. Tumors regulate certain immune checkpoint pathways as a major mechanism of immune resistance. Because immune checkpoints are initiated by ligand-receptor interactions, blockade by antibodies provides a rational therapeutic approach. Although targeted therapies are clinically successful, they are often short-lived due to rapid development of resistance. Immunotherapies offer one notable advantage. Enhancing the cell-mediated immune response against tumor cells leads to generation of a long-term memory lymphocyte population patrolling the body to attack growth of any new tumor cells, thereby sustaining the therapeutic effects. Furthermore, early clinical results suggest that combination immunotherapies offer even more potent antitumor activity. This review is intended to provide an introduction to immune checkpoint inhibitors and discusses the scientific overview of cancer immunotherapy, mechanisms of the inhibitors, clinical pharmacology considerations, advances in combination therapies, and challenges in drug development.

Development of PD-1/PD-L1 Pathway in Tumor Immune Microenvironment and Treatment for Non-Small Cell Lung Cancer

Lung cancer is currently the leading cause of cancer-related death in worldwide, non-small cell lung cancer (NSCLC) accounts for about 85% of all lung cancers. Surgery, platinum-based chemotherapy, molecular targeted agents and radiotherapy are the main treatment of NSCLC. With the strategies of treatment constantly improving, the prognosis of NSCLC patients is not as good as before, new sort of treatments are needed to be exploited. Programmed death 1 (PD-1) and its ligand PD-L1 play a key role in tumor immune escape and the formation of tumor microenvironment, closely related with tumor generation and development. Blockading the PD-1/PD-L1 pathway could reverse the tumor microenvironment and enhance the endogenous antitumor immune responses. Utilizing the PD-1 and/or PD-L1 inhibitors has shown benefits in clinical trials of NSCLC. In this review, we discuss the basic principle of PD-1/PD-L1 pathway and its role in the tumorigenesis and development of NSCLC. The clinical development of PD-1/PD-L1 pathway inhibitors and the main problems in the present studies and the research direction in the future will also be discussed.

Directed T-cell therapies for leukemia and lymphoma after hematopoietic stem cell transplant: beyond chimeric antigen receptors

This review focuses on the recent advances utilizing adoptive T-cell immunotherapies for patients after hematopoietic stem cell transplant using T cells after autologous transplant to treat the highest risk patients. The particular emphasis is the use of T cells to treat leukemias and lymphomas with gene transfer and nongene transfer approaches to direct specificity to tumor associated antigens. In this review, we will highlight how these novel therapeutics can be successfully used to prevent or treat high-risk patients who relapse after hematopoietic stem cell transplant.

Expression of immune checkpoint molecules of T cell immunoglobulin and mucin protein 3/galectin-9 for NK cell suppression in human gastrointestinal stromal tumors

Monoclonal antibody therapy for immune checkpoint blockade has achieved promising results for several types of malignant tumors. For the future treatment of gastrointestinal stromal tumors (GISTs) by immune checkpoint blockade, expression of immune checkpoint-related molecules that suppress antitumor immunity in GISTs was examined. Infiltration of immune cell types into 19 GIST tissues was analyzed by immunohistochemistry, and expression of T cell immunoglobulin and mucin protein 3 (Tim-3) and programmed cell death-1 (PD-1) in the infiltrated immune cells was examined by immunofluorescence microscopy. The expression status of galectin-9 in the GIST tumor cells was also determined by immunohistochemistry. All the GIST tissues showed CD8+ T cell infiltration and 8 showed CD56+ natural killer (NK) cell infiltration, and the numbers of infiltrated CD8+ T and NK cells were strongly correlated. However, these CD8+ T and NK cells were CD69-negative inactivated cells. Tim-3 was expressed in the infiltrated NK cells in 6/8 (75%) of the GIST tissues. Expression of galectin-9, a ligand of Tim-3, was observed in 13/19 (68.4%) GIST tissues and all of the GIST tissues with Tim-3+ NK cell infiltration showed positive galectin-9 expression. No PD-1 expression in the infiltrated NK cells and neither Tim-3 nor PD-1 expression was observed in the infiltrated CD8+ T cells. Interaction between Tim-3 in infiltrated NK cells and galectin-9 in tumor cells may be involved in an immune checkpoint mechanism for suppression of antitumor immunity in GISTs. Blockade of the Tim-3/galectin-9 pathway may become a new strategy for GIST treatment.

PD-1 pathway inhibitors: changing the landscape of cancer immunotherapy

BACKGROUND

Immunotherapeutic approaches to treating cancer have been evaluated during the last few decades with limited success. An understanding of the checkpoint signaling pathway involving the programmed death 1 (PD-1) receptor and its ligands (PD-L1/2) has clarified the role of these approaches in tumor-induced immune suppression and has been a critical advancement in immunotherapeutic drug development.

METHODS

A comprehensive literature review was performed to identify the available data on checkpoint inhibitors, with a focus on anti-PD-1 and anti-PD-L1 agents being tested in oncology. The search included Medline, PubMed, the ClinicalTrials.gov registry, and abstracts from the American Society of Clinical Oncology meetings through April 2014. The effectiveness and safety of the available anti-PD-1 and anti-PD-L1 drugs are reviewed.

RESULTS

Tumors that express PD-L1 can often be aggressive and carry a poor prognosis. The anti-PD-1 and anti-PD-L1 agents have a good safety profile and have resulted in durable responses in a variety of cancers, including melanoma, kidney cancer, and lung cancer, even after stopping treatment. The scope of these agents is being evaluated in various other solid tumors and hematological malignancies, alone or in combination with other therapies, including other checkpoint inhibitors and targeted therapies, as well as cytotoxic chemotherapy.

CONCLUSIONS

The PD-1/PD-L1 pathway in cancer is implicated in tumors escaping immune destruction and is a promising therapeutic target. The development of anti-PD-1 and anti-PD-L1 agents marks a new era in the treatment of cancer with immunotherapies. Early clinical experience has shown encouraging activity of these agents in a variety of tumors, and further results are eagerly awaited from completed and ongoing studies.

Current state of anti-PD-L1 and anti-PD-1 agents in cancer therapy

Immunotherapy for the treatment of cancer is rapidly evolving from therapies that globally and non-specifically simulate the immune system to more targeted activation of individual components of the immune system. The net result of this targeted approach is decreased toxicity and increased efficacy of immunotherapy. More specifically, therapies that inhibit the interaction between programmed death ligand 1 (PD-L1), present on the surface of tumor or antigen-presenting cells, and programmed death 1 (PD-1), present on the surface of activated lymphocytes, are generating much excitement and enthusiasm, even in malignancies that are not traditionally considered to be immunogenic. Herein, we review the current landscape of anti-PD-1 and anti-PD-L1 therapies in the world of oncology. We have performed a comprehensive literature search on the data available through PubMed, Medline, Scopus, the ClinicalTrials.gov registry, and abstracts from major oncology meetings in order to summarize the clinical data of anti-PD-1/PD-L1 therapies.

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.

The PD-1/PD-L1 pathway: biological background and clinical relevance of an emerging treatment target in immunotherapy

INTRODUCTION

The co-inhibitory receptor programmed death 1 (PD-1) and its ligands are key regulators in a wide spectrum of immune responses and play a critical role in autoimmunity and self-tolerance as well as in cancer immunology. Emerging evidence suggests that cancer cells might use the PD-1/PD-ligand (PD-L) pathway to escape anti-tumor immunity. Based on this evidence, early phase human clinical trials targeting the PD-1/PD-L pathway are currently underway for multiple human cancers.

AREAS COVERED

The role of the PD-1/PD-L pathway in autoimmune disease, viral infections as well as in malignant neoplasms is discussed and an overview of the existing therapeutics as well as the results of clinical trials targeting this pathway in cancer is given.

EXPERT OPINION

The PD-1/PD-L pathway represents an important mechanism of immune evasion for malignant neoplasms. Early clinical trials indicate effectiveness of PD-1/PD-L pathway blockade in several solid cancers. However, greater insight into the exact mechanisms by which tumors are able to evade anti-tumor immunity is needed to increase clinical effectiveness, for example by combination blockade of diverse co-inhibitory receptors.

Cytotoxic T lymphocytes for leukemia and lymphoma

This chapter focuses on the recent advances in adoptive T-cell immunotherapies, not only for patients after hematopoietic stem cell transplantation, but also in the autologous setting using T cells early in the disease process for the treatment of the highest-risk patients with leukemias and lymphomas. The particular emphasis is to highlight the role of T-cell therapies for hematologic malignancies using a non-gene-transfer approach to direct specificity, including the clinical use of T-cell therapies for EBV-associated lymphomas and strategies for targeting nonviral lymphoma- and leukemia-associated antigens.

Reprint of: Back to the future! The evolving role of maintenance therapy after hematopoietic stem cell transplantation

Relapse is a devastating event for patients with hematologic cancers treated with hematopoietic stem cell transplantation. In most situations, relapse treatment options are limited. Maintenance therapy offers the possibility of delaying or avoiding disease recurrence, but its role remains unclear in most conditions that we treat with transplantation. Here, Dr. Hourigan presents an overview of minimal residual disease (MRD) measurement in hematologic malignancies and the applicability of MRD-based post-transplantation interventions. Dr. McCarthy reviews current knowledge of maintenance therapy in the autologous transplantation context, with emphasis on immunologic interventions and immune modulation strategies designed to prevent relapse. Dr. de Lima discusses current lines of investigation in disease recurrence prevention after allogeneic transplantation, focusing on acute myeloid leukemia and myelodysplastic syndrome.

Immunotherapy for Lung Cancer: Has it Finally Arrived?

The possible link between infection/inflammation/immune activation and a cancer patient’s outcome from both a causative and outcome point of view has long been postulated. Substantial progress in the understanding of tumor-associated antigens/epitopes, immune cellular subpopulations, cytokine pathways/expression, the tumor microenvironment, and the balance between tumor-immune suppression and stimulation have been made over the past decade. This knowledge has heralded a new era of tumor immunotherapy utilizing vaccines, immune checkpoint inhibition, and oncolytic viruses. Despite significant progress in the molecular era now with targeted therapeutics such as EGFR tyrosine kinase inhibitors and ALK fusion protein inhibitors that have significantly improved the outcome of these specific lung cancer subpopulations, the overall 5 year survival for all non-small cell lung cancer (NSCLC) is still <20%. Unlike malignancies such as malignant melanoma, renal cell carcinoma, and neuroblastoma given their documented spontaneous remission rates lung cancer historically has been felt to be resistant to immune approaches likely related to an immunosuppressive tumor microenvironment and/or lack of immune recognition. Defining responding populations, understanding the mechanism(s) underlying durable immune responses, and the role of chemotherapy, radiation, oncolytic viruses, and other tumor disrupting agents in augmenting immune responses have led to improved optimization of immune therapeutic strategies. The purpose of this review is to focus on the recent advances in lung immunotherapy with an emphasis on recent clinical trials in the last 5 years in NSCLC.

Expression of programmed death 1 is correlated with progression of osteosarcoma

Accumulating bodies of evidence indicate that immune dysregulation plays a key role in the development of osteosarcoma (OS). Programmed death 1 (PD-1) is a surface receptor expressed on activated and exhausted T cells, which mediate T-cell inhibition upon binding with its ligand. Researches on PD-1 and OS remain extremely limited. Here, we investigated whether PD-1 could be involved in the development of OS. Expression of PD-1 was measured by flow cytometry on peripheral CD4+ and CD8+ T cells from 56 OS cases and 42 healthy controls. Data revealed that percentages of PD-1 were significantly upregulated on both peripheral CD4+ and CD8+ T cells from OS patients (p < 0.001 and p < 0.001, respectively). Patients with different tumor locations did not present obvious variations in PD-1 level. However, patients with metastasis showed significantly higher level of PD-1 on CD4+ T cells than those without metastasis (p < 0.001). Furthermore, PD-1 expression on CD4+ T cells started to increase in stage III, whereas PD-1 expression on CD8+ T cells started to increase in stage II. In addition, patients with pathological fracture were observed to have elevated PD-1 on both CD4+ and CD8+ T cells. These data suggest that PD-1 is involved in the pathogenesis of OS, especially in the progression of disease.

Developments in HIV-1 immunotherapy and therapeutic vaccination

Since the human immunodeficiency virus (HIV-1) pandemic began, few prophylactic vaccines have reached phase III trials. Only one has shown partial efficacy in preventing HIV-1 infection. The introduction of antiretroviral therapy (ART) has had considerable success in controlling infection and reducing transmission but in so doing has changed the nature of HIV-1 infection for those with access to ART. Access, compliance, and toxicity alongside the emergence of serious non-AIDS morbidity and the sometimes poor immune reconstitution in ART-treated patients have emphasized the need for additional therapies. Such therapy is intended to contribute to control of HIV-1 infection, permit structured treatment interruptions, or even establish a functional cure of permanently suppressed and controlled infection. Both immunotherapy and therapeutic vaccination have the potential to reach these goals. In this review, the latest developments in immunotherapy and therapeutic vaccination are discussed.

Immunotherapeutic strategies in autoimmune uveitis

Autoimmune uveitis is an organ-specific disorder characterized by irreversible lesions to the eye that predominantly affect people in their most productive years and is among the leading causes of visual deficit and blindness. Currently available therapies are effective in the treatment of a wide spectrum of uveitis, but are often associated with severe side effects. Here, we review ongoing research with promising immunomodulatory therapeutic strategies, describing their specific features, interactions and the responses triggered by the targeted immune molecules that aim to minimize clinical complications and the likelihood of disease relapse. We first review the main features of the disease, diagnostic tools, and traditional forms of therapy, as well as the animal models predominantly used to understand the pathogenesis and test the novel intervention approaches aiming to control the acute immune and inflammatory responses and to dampen chronic responses. Both exploratory research and clinical trials have targeted either the blockade of effector pathways or of their companion co-stimulatory molecules. Examples of targets are T cell receptors (CD3), their co-stimulatory receptors (CD28, CTLA-4) and corresponding ligands (B7-1 and B7-2, also known as CD80 and CD86), and cytokines like IL-2 and their receptors. Here, we summarize the available evidence on effectiveness of these treatments in human and experimental uveitis and highlight a novel CD28 antagonist monovalent Fab′ antibody, FR104, which has shown preclinical efficacy suppressing effector T cells while enhancing regulatory T cell function and immune tolerance in a humanized graft-versus-host disease (GVHD) mice model and is currently being tested in a mouse autoimmune uveitis model with encouraging results.

The effect of metronomic versus standard chemotherapy on the regulatory to effector T-cell equilibrium in cancer patients

BACKGROUND

The host's immune system is crucially involved in cancer development and progression. The ratio of regulatory to effector T-cells, as well as the interplay of T-cells with therapeutic agents, impact on cancer prognosis. The current study aimed to comparatively investigate the effect of metronomic and standard chemotherapy on the number and functionality of peripheral regulatory and effector T-cells in cancer patients.

METHODS

CD4+CD25+ regulatory and CD4+CD25- effector T-cells were purified from the peripheral blood of 36 cancer patients and co-cultured in the presence of a polyclonal stimulus. The proliferative capacity and frequency of CD4+CD25+/CD4+CD25- T-cells were analysed before and during various chemotherapeutic regimes, by ELISA and flow cytometry, respectively.

RESULTS

Chemotherapy shifted immune responses in favour of regulatory T-cells. The relative ratio of regulatory to effector T-cells increased, and the T-cell-mediated suppressive activity of regulatory on effector T-cells was augmented. This effect was more profound in metronomic than in standard chemotherapeutic approaches. Moreover, an association between the chemotherapy strategy followed and the mode of action of specific drugs (anti-mitotic, anti-DNA) was revealed.

CONCLUSIONS

In comparison to standard chemotherapeutic strategies, metronomic approaches, though more patient-friendly, result in a significantly more prominent expansion of regulatory T-cells that aggravate the regulatory to effector T-cell imbalance. Our findings impact on the modulation of chemotherapy-treated patients' anti-tumor immunity and, thus, may be proven useful for selecting the most advantageous drug-delivery strategy, particularly when immunotherapeutics are eventually to be applied.

Harnessing the power of the immune system via blockade of PD-1 and PD-L1: a promising new anticancer strategy

Cancer cells employ several mechanisms to evade the immune system of their host, thus escaping immune recognition and elimination. Of particular interest is a cancer cell's ability to co-opt the immune system's innate ligands and inhibitory receptors (also known as checkpoints), thus creating an immunosuppressive microenvironment that downregulates T-cell activation and cell signaling. The recent development of the checkpoint inhibitors anti-programmed death-1 and anti-programmed death ligand-1 has generated an enormous amount of interest as a potential new anticancer strategy in solid tumors, particularly in non-small-cell lung cancer, renal cell carcinoma and melanoma. Data suggest significant disease response rates using anti-programmed death-1 and anti-programmed death ligand-1 antibodies, even in heavily pretreated patients. Future directions include optimization of drug delivery sequence and combination of immunotherapy with other therapies including cytotoxic chemotherapy, radiation, antiangiogenic agents and small-molecule tyrosine kinase inhibitors.

Back to the future! The evolving role of maintenance therapy after hematopoietic stem cell transplantation

Relapse is a devastating event for patients with hematologic cancers treated with hematopoietic stem cell transplantation. In most situations, relapse treatment options are limited. Maintenance therapy offers the possibility of delaying or avoiding disease recurrence, but its role remains unclear in most conditions that we treat with transplantation. Here, Dr. Hourigan presents an overview of minimal residual disease (MRD) measurement in hematologic malignancies and the applicability of MRD-based post-transplantation interventions. Dr. McCarthy reviews current knowledge of maintenance therapy in the autologous transplantation context, with emphasis on immunologic interventions and immune modulation strategies designed to prevent relapse. Dr. de Lima discusses current lines of investigation in disease recurrence prevention after allogeneic transplantation, focusing on acute myeloid leukemia and myelodysplastic syndrome.