Immuno-regulatory antibodies for the treatment of cancer

Durvalumab with or without tremelimumab for patients with recurrent or metastatic squamous cell carcinoma of the head and neck: a systematic review and meta-analysis

Objective

Head and neck squamous cell carcinoma (HNSCC) ranks as the sixth most prevalent cancer worldwide, significantly impacting patients' quality of life. Immune checkpoint inhibitors (ICI) have been employed in the treatment of recurrent/metastatic (R/M)-HNSCC patients. This meta-analysis aims to assess the efficacy and safety of durvalumab monotherapy compared to the combination of durvalumab and tremelimumab in R/M-HNSCC patients.

Methods

Relevant studies were systematically searched in PubMed, Embase, and Cochrane Library databases. All articles comparing durvalumab monotherapy with the combination with durvalumab and tremelimumab in R/M-HNSCC treatment were included. Additionally, the references of identified studies were screened if necessary.

Result

A total of 1298 patients from three studies comparing durvalumab with durvalumab and tremelimumab in treating R/M-HNSCC were include in this meta-analysis. Our findings revealed no significant difference in objective response rate (ORR) [odds ratio (OR): 1.15, 95% confidence interval (CI): 0.85 to 1.56, P = 0.36] and disease control rate (DCR) (OR=1.08, 95%CI: 0.86 to 1.37, P = 0.51). Similar outcomes were observed in overall survival (OS), progression-free survival (PFS), and duration of response (DoR). Regarding safety, there was no significant difference in the incidence of treatment-related adverse events (trAEs) between the two groups (OR=1.26, 95%CI: 0.81 to 1.94, P = 0.30). However, patients treated with the combination therapy exhibited a higher incidence of grade 3-4 trAEs (OR=1.93, 95%CI: 1.36 to 2.73, P = 0.0002) and a greater likelihood of discontinuing treatment due to trAEs (OR=2.07, 95%CI: 1.12 to 3.85, P = 0.02). There was no significant difference in the occurrence of severe trAEs leading to death (OR=1.36, 95%CI: 0.47 to 3.96, P = 0.57).

Conclusion

This meta-analysis suggests that R/M-HNSCC patients receiving the combination of durvalumab and tremelimumab may achieve comparable outcomes in terms of ORR, DCR, OS, PFS, and DoR, without significant differences. However, the combination therapy is associated with a higher incidence of grade 3-4 trAEs and an increased likelihood of treatment discontinuation due to trAEs. These findings highlight the need for cautious consideration of the combination of durvalumab and tremelimumab in R/M-HNSCC patients, which should be further evaluated in high-quality studies.

Immune checkpoint inhibitor induced nephrotoxicity: An ongoing challenge

Although immune checkpoint inhibitors (ICIs) have dramatically revolutionized the field of oncology over the last decade, severe immune-related adverse events (irAEs) are potentially life-threatening. In comparison with toxicities involving the skin, gastrointestinal tract and endocrine system, nephrotoxicity is less common but often underestimated due to difficult diagnosis. Management usually consists of treatment discontinuation and/or corticosteroid use. In this review, we summarize current knowledge of ICI-induced nephrotoxicity, evaluating drawbacks and future perspectives.

Checkpoint molecules on infiltrating immune cells in colorectal tumor microenvironment

Colorectal cancer (CRC) is one of the most prevalent cancer types worldwide, with a high mortality rate due to metastasis. The tumor microenvironment (TME) contains multiple interactions between the tumor and the host, thus determining CRC initiation and progression. Various immune cells exist within the TME, such as tumor-infiltrating lymphocytes (TILs), tumor-associated macrophages (TAMs), and tumor-associated neutrophils (TANs). The immunotherapy approach provides novel opportunities to treat solid tumors, especially toward immune checkpoints. Despite the advances in the immunotherapy of CRC, there are still obstacles to successful treatment. In this review, we highlighted the role of these immune cells in CRC, with a particular emphasis on immune checkpoint molecules involved in CRC pathogenesis.

Radiotherapy-Immunotherapy Combination: How Will We Bridge the Gap Between Pre-Clinical Promise and Effective Clinical Delivery?

Radiotherapy (RT) is highly effective at directly killing tumor cells and plays an important part in cancer treatments being delivered to around 50% of all cancer patients. The additional immunomodulatory properties of RT have been investigated, and if exploited effectively, have the potential to further improve the efficacy of RT and cancer outcomes. The initial results of combining RT with immunomodulatory agents have generated promising data in pre-clinical studies, which has in turn led to a large number of RT and immunotherapy clinical trials. The overarching aim of these combinations is to enhance anti-tumor immune responses and improve responses rates and patient outcomes. In order to maximize this undoubted opportunity, there remain a number of important questions that need to be addressed, including: (i) the optimal RT dose and fractionation schedule; (ii) the optimal RT target volume; (iii) the optimal immuno-oncology (IO) agent(s) to partner with RT; (iv) the optimal site(s)/route(s) of administration of IO agents; and finally, the optimal RT schedule. In this review, we will summarize progress to date and identify current gaps in knowledge that need to be addressed in order to facilitate effective clinical translation of RT and IO agent combinations.

Boosting the Immune Response with the Combination of Electrochemotherapy and Immunotherapy: A New Weapon for Squamous Cell Carcinoma of the Head and Neck?

Simple Summary

Squamous cell carcinoma of the head and neck (SCCHN) represents a problem of utmost concern and, for many clinicians and surgeons, an enormous challenge. Currently, new generation immunotherapy which avails of check point inhibitors, namely molecules capable of restoring the host’s immune system strongly depressed by the presence of tumor cells, is gaining increasing importance. Nevertheless, immunotherapy alone is not always effective in some patients, in particular those having a bulky and highly symptomatic disease. These last require the addition of locoregional strategies able to reduce the tumor mass and to assist immunotherapy in producing its effect. Electrochemotherapy (ECT) is a strategy able to associate the electroporation of tumor cells and the simultaneous administration of antineoplastic drugs, so as to concentrate the latter directly in the tumor site. The combination of ECT and immunotherapy could be very effective particularly in patients having a bulky/highly symptomatic SCCHN.

Abstract

Head and neck squamous cell carcinomas (SCCHN) are not rare malignancies and account for 7% of all solid tumors. Prognosis of SCCHN patients strongly depends on tumor extension, site of onset, and genetics. Advanced disease (recurrent/metastatic) is associated with poor prognosis, with a median overall survival of 13 months. In these patients, immunotherapy may represent an interesting option of treatment, given the good results reached by check-point inhibitors in clinical practice. Nevertheless, only a minor number of patients with advanced disease respond to immunotherapy, and, disease progressions/hyper-progressions are common. The latter could be a very difficult issue, especially in patients having a wide and highly symptomatic head/neck mass. Given the potentiality to boost the immune response of some local modalities, such as electrochemotherapy, a possible future approach may take into account the combination of electrochemotherapy and immunotherapy to treat patients affected by SCCHN, suffering from symptomatic lesions that need rapid debulking.

Reasoning the effect of immunotherapy after chemoradiation in the PACIFIC trial

Durvalumab consolidation after chemoradiation has been a giant leap in the treatment of stage III non-small-cell lung cancer with an unprecedented 16.8-month median progression-free survival. PACIFIC trial is a new foray into chemoimmunotherapy trials where we apply our knowledge of 'immunogenic cell death' and 'Abscopal' effect of radiation in the clinic. Our understanding of immunotherapy after chemoradiation treatment and application of immunogenic cell death biomarkers in future trials may be the approach we need to maximize benefit of these treatments in the appropriate patients.

Cost effectiveness vs. affordability in the age of immuno-oncology cancer drugs

INTRODUCTION

After years of setback, cancer immunotherapy has begun to yield clinical dividends, which are changing the treatment landscape and offering cancer patients the potential for long-term survival, reduced treatment-related toxicity and improved quality-of-life. Using the immune system to treat cancer is known as 'Immuno-oncology' (IO) and agents are sub-classified by their ability to enhance anti-tumor response or to direct the immune system to attack cancer cells via tumor-associated antigens. Areas covered: Clinical trials have demonstrated the effectiveness of several IO agents in many disease sites such as early and advanced stage melanoma, advanced non-small cell lung cancer, bladder, head and neck, gastric, kidney as well as Hodgkin's lymphoma. Notwithstanding the therapeutic excitement generated for patients and clinicians alike, an important consideration is treatment cost, which can reach more than $US100,000 per patient annually. The cost of the drugs, coupled with high disease prevalence and the ever-expanding number of indications, means the current cost trajectory is untenable for most healthcare systems to sustain. Expert commentary: In this paper, the approved IO drugs and those in clinical development are reviewed. The issue of cost effectiveness vs. affordability is then addressed and suggestions that facilitate patient access and long-term sustainability are presented.

Protein Expression in Tonsillar and Base of Tongue Cancer and in Relation to Human Papillomavirus (HPV) and Clinical Outcome

Human papillomavirus (HPV) is a major etiological factor for tonsillar and the base of tongue cancer (TSCC/BOTSCC). HPV-positive and HPV-negative TSCC/BOTSCC present major differences in mutations, mRNA expression and clinical outcome. Earlier protein studies on TSCC/BOTSCC have mainly analyzed individual proteins. Here, the aim was to compare a larger set of cancer and immune related proteins in HPV-positive and HPV-negative TSCC/BOTSCC in relation to normal tissue, presence of HPV, and clinical outcome. Fresh frozen tissue from 42 HPV-positive and 17 HPV-negative TSCC/BOTSCC, and corresponding normal samples, were analyzed for expression of 167 proteins using two Olink multiplex immunoassays. Major differences in protein expression between TSCC/BOTSCC and normal tissue were identified, especially in chemo- and cytokines. Moreover, 34 proteins, mainly immunoregulatory proteins and chemokines, were differently expressed in HPV-positive vs HPV-negative TSCC/BOTSCC. Several proteins were potentially related to clinical outcome for HPV-positive or HPV-negative tumors. For HPV-positive tumors, these were mostly related to angiogenesis and hypoxia. Correlation with clinical outcome of one of these, VEGFA, was validated by immunohistochemistry. Differences in immune related proteins between HPV-positive and HPV-negative TSCC/BOTSCC reflect the stronger activity of the immune defense in the former. Angiogenesis related proteins might serve as potential targets for therapy in HPV-positive TSCC/BOTSCC.

The transition from HLA-I positive to HLA-I negative primary tumors: the road to escape from T-cell responses

MHC/HLA class I loss in cancer is one of the main mechanisms of tumor immune escape from T-cell recognition and destruction. Tumor infiltration by T lymphocytes (TILs) and by other immune cells was first described many years ago, but has never been directly and clearly linked to the destruction of HLA-I positive and selection of HLA-I negative tumor cells. The degree and the pattern of lymphocyte infiltration in a tumor nest may depend on antigenicity and the developmental stages of the tumors. In addition, it is becoming evident that HLA-I expression and tumor infiltration have a direct correlation with tumor tissue reorganization. We observed that at early stages (permissive Phase I) tumors are heterogeneous, with both HLA-I positive and HLA-negative cancer cells, and are infiltrated by TILs and M1 macrophages as a part of an active anti-tumor Th1 response. At later stages (encapsulated Phase II), tumor nests are mostly HLA-I negative with immune cells residing in the peri-tumoral stroma, which forms a granuloma-like encapsulated tissue structure. All these tumor characteristics, including tumor HLA-I expression pattern, have an important clinical prognostic value and should be closely and routinely investigated in different types of cancer by immunologists and by pathologists. In this review we summarize our current viewpoint about the alterations in HLA-I expression in cancer and discuss how, when and why tumor HLA-I losses occur. We also provide evidence for the negative impact of tumor HLA-I loss in current cancer immunotherapies, with the focus on reversible ('soft') and irreversible ('hard') HLA-I defects.

Small molecules targeting histone demethylase genes (KDMs) inhibit growth of temozolomide-resistant glioblastoma cells

In glioblastoma several histone demethylase genes (KDM) are overexpressed compared to normal brain tissue and the development of Temozolomide (TMZ) resistance is accompanied by the transient further increased expression of KDM5A and other KDMs following a mechanism that we defined as “epigenetic resilience”. We hypothesized that targeting KDMs may kill the cells that survive the cytotoxic therapy.

We determined the effect of JIB 04 and CPI-455, two KDM inhibitors, on glioblastoma cells and found that both molecules are more effective against TMZ-resistant rather than native cells.

Because of its lower IC50, we focused on JIB 04 that targets KDM5A and other KDMs as well. We have shown that this molecule activates autophagic and apoptotic pathways, interferes with cell cycle progression, inhibits cell clonogenicity and dephosphorylates Akt thus inactivating a potent pro-survival pathway. We performed combination temozolomide/JIB 04 in vitro treatments showing that these two molecules, under certain conditions, have a strong synergic effect and we hypothesize that JIB 04 intercepts the cells that escape the G2 block exerted by TMZ. Finally we studied the permeability of JIB 04 across the blood-brain barrier and found that this molecule reaches bioactive concentration in the brain; furthermore a pilot in vivo experiment in an orthotopic GB xenograft model showed a trend toward longer survival in treated mice with an Hazard Ratio of 0.5.

In conclusion we propose that the combination between cytotoxic drugs and molecules acting on the epigenetic landscape may offer the opportunity to develop new therapies for this invariably lethal disease.

The influence of radiation in the context of developing combination immunotherapies in cancer

In addition to tumouricidal activity, radiotherapy is now recognized to display potent immunostimulatory properties that can contribute to the generation of anti-cancer immune responses. Treatment with radiation can induce a variety of pro-immunogenic and phenotypic changes in malignant cells, and recalibrate the immune contexture of the tumour microenvironment, leading to enhanced activation of the innate immune system, and priming of tumour-specific T-cell immunity. The immune-dependent effects of radiotherapy provide a sound rationale for the development of combination strategies, whereby the immunomodulatory properties of radiation can be exploited to augment the activity of immunotherapeutic agents. Encouraged by the recent success of breakthrough therapies such as immune checkpoint blockade, and a wealth of experimental data demonstrating the efficacy of radiotherapy and immunotherapy combinations, the clinical potential of this approach is now being explored in numerous trials. Successful translation will require careful consideration of the most suitable dose and fractionation of radiation, choice of immunotherapy and optimal sequencing and scheduling regimen. Immunological control of cancer is now becoming a clinical reality. There is considerable optimism that the development of effective radiotherapy and immunotherapy combinations with the capacity to induce durable, systemic immunity will further enhance patient outcome and transform the future management of cancer.

Management of High-Risk Squamous Cell Carcinoma of the Skin

OPINION STATEMENT

Non-melanoma skin cancer (NMSC) is the most common malignancy in the USA, with cutaneous squamous cell carcinomas (cSCCs) constituting approximately 20 % of all NMSC. While cSCCs typically behave in an indolent fashion and can be cured with local destructive or surgical methods, a small subset metastasizes and induces significant morbidity and mortality. Identifying and aggressively treating these "high-risk" cSCCs (HRcSCCs) is thus paramount. Recent improvements in staging cSCCs appear to offer better risk stratification than earlier staging criteria. Radiologic imaging and sentinel lymph node biopsy may be beneficial in certain cases of HRcSCC, although more studies are needed before these techniques should be uniformly incorporated into management. Surgery with complete margin control, such as that offered by the Mohs micrographic technique, represents the first-line treatment for these tumors. Radiation therapy is likely most beneficial in the adjuvant setting. Chemotherapy is typically best reserved for patients with metastatic or locally advance disease that is not controllable with surgical and/or radiation therapies. Newer targeted treatments, such as EGFR inhibitors and immunotherapies may offer greater efficacy in these settings, although further evaluation is needed.

Antibody-targeted nanoparticles for cancer treatment

Nanoparticles (NPs) are diverse and versatile with physical properties that can be employed for use in cancer medicine. Targeting NPs using antibodies and antibody fragments could overcome some of the limitations seen with current targeted therapies. This review will discuss the role of antibody-targeted NPs in the treatment of cancer: as delivery vehicles, targeted theranostic agents and in the evolving field of cancer hyperthermia.

A TLR7 agonist enhances the antitumor efficacy of obinutuzumab in murine lymphoma models via NK cells and CD4 T cells

Anti-CD20 monoclonal antibodies (mAb) such as rituximab have been proven to be highly effective at improving outcome in B-cell malignancies. However, many patients ultimately relapse and become refractory to treatment. The glycoengineered anti-CD20 mAb obinutuzumab was developed to induce enhanced antibody-dependent cellular cytotoxicity, antibody-dependent phagocytosis and direct cell death and was shown to lead to improved outcomes in a randomized study in B-CLL. We hypothesized that immune stimulation through Toll-like receptor 7 (TLR7) agonism in combination with obinutuzumab would further enhance lymphoma clearance and the generation of long-term antitumor immune responses. Here we demonstrate, in syngeneic human CD20 (hCD20)-expressing models of lymphoma, that systemic administration of a TLR7 agonist (R848) increases responses when administered in combination with obinutuzumab and protects against disease recurrence. Depletion studies demonstrate that primary antitumor activity is dependent on both NK cells and CD4+ T cells but not on CD8+ T cells. However, both CD4+ and CD8+ T cells appear necessary for the generation of protective immunological memory. Importantly, increased tumor-free survival post obinutuzumab and R848 combination therapy was seen in hCD20 transgenic mice, which express hCD20 on normal B cells. These findings provide a rationale for clinical testing of obinutuzumab in combination with systemically administered TLR7 agonists to further improve outcome.

Immunotherapy for Head and Neck Squamous Cell Carcinoma: A Review of Current and Emerging Therapeutic Options

Advances in the field of cancer immunotherapy have occurred rapidly over the past decade. Exciting results from clinical trials have led to new treatment options and improved survival for patients with a myriad of solid tumor pathologies. However, questions remain unanswered regarding duration and timing of therapy, combination regimens, appropriate biomarkers of disease, and optimal monitoring of therapeutic response. This article reviews emerging immunotherapeutic agents and significant clinical trials that have led to advancements in the field of immuno-oncology for patients with head and neck squamous cell carcinoma.

IMPLICATIONS FOR PRACTICE

This review article summarizes recently developed agents that harness the immune system to fight head and neck squamous cell carcinoma. A brief review of the immune system and its role in cancer development is included. Recently completed and emerging therapeutic trials centering on the immune system and head and neck cancer are reviewed.

Biological mechanisms of immune escape and implications for immunotherapy in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy with high morbidity and mortality. Despite advances in cytotoxic therapies and surgical techniques, overall survival (OS) has not improved over the past few decades. This emphasises the need for intense investigation into novel therapies with good tumour control and minimal toxicity. Cancer immunotherapy has led this endeavour, attempting to improve tumour recognition and expand immune responses against tumour cells. While various forms of HNSCC immunotherapy are in preclinical trials, the most promising direction thus far has been with monoclonal antibodies (mAbs), targeting growth factor and immune checkpoint receptors. Preclinical and early phase trials have shown unprecedented efficacy with minimal adverse effects. This article will review biological mechanisms of immune escape and implications for immunotherapy in HNSCC.

Rejection versus escape: the tumor MHC dilemma

Most tumor cells derive from MHC-I-positive normal counterparts and remain positive at early stages of tumor development. T lymphocytes can infiltrate tumor tissue, recognize and destroy MHC class I (MHC-I)-positive cancer cells ("permissive" phase I). Later, MHC-I-negative tumor cell variants resistant to T-cell killing emerge. During this process, tumors first acquire a heterogeneous MHC-I expression pattern and finally become uniformly MHC-I-negative. This stage (phase II) represents a "non-permissive" encapsulated structure with tumor nodes surrounded by fibrous tissue containing different elements including leukocytes, macrophages, fibroblasts, etc. Molecular mechanisms responsible for total or partial MHC-I downregulation play a crucial role in determining and predicting the antigen-presenting capacity of cancer cells. MHC-I downregulation caused by reversible ("soft") lesions can be upregulated by TH1-type cytokines released into the tumor microenvironment in response to different types of immunotherapy. In contrast, when the molecular mechanism of the tumor MHC-I loss is irreversible ("hard") due to a genetic defect in the gene/s coding for MHC-I heavy chains (chromosome 6) or beta-2-microglobulin (B2M) (chromosome 15), malignant cells are unable to upregulate MHC-I, remain undetectable by cytotoxic T-cells, and continue to grow and metastasize. Based on the tumor MHC-I molecular analysis, it might be possible to define MHC-I phenotypes present in cancer patients in order to distinguish between non-responders, partial/short-term responders, and likely durable responders. This highlights the need for designing strategies to enhance tumor MHC-I expression that would allow CTL-mediated tumor rejection.

Transcriptome profiling in oral cavity and esophagus tissues from (S)-N'-nitrosonornicotine-treated rats reveals candidate genes involved in human oral cavity and esophageal carcinogenesis

Recently, we have shown that (S)-N'-Nitrosonornicotine [(S)-NNN], the major form of NNN in tobacco products, is a potent oral cavity and esophageal carcinogen in rats. To determine the early molecular alterations induced by (S)-NNN in the oral and esophageal mucosa, we administered the carcinogen to rats in the drinking water for 10 wk and global gene expression alterations were analyzed by RNA sequencing. At a false discovery rate P-value < 0.05 and fold-change ≥2, we found alterations in the level of 39 genes in the oral cavity and 69 genes in the esophagus. Validation of RNA sequencing results by qRT-PCR assays revealed a high cross-platform concordance. The most significant impact of exposure to (S)-NNN was alteration of genes involved in immune regulation (Aire, Ctla4, and CD80), inflammation (Ephx2 and Inpp5d) and cancer (Cdkn2a, Dhh, Fetub B, Inpp5d, Ly6E, Nr1d1, and Wnt6). Consistent with the findings in rat tissues, most of the genes were deregulated, albeit to different degrees, in immortalized oral keratinocytes treated with (S)-NNN and in non-treated premalignant oral cells and malignant oral and head and neck squamous cells. Furthermore, interrogation of TCGA data sets showed that genes deregulated by (S)-NNN in rat tissues (Fetub, Ly6e, Nr1d1, Cacna1c, Cd80, and Dgkg) are also altered in esophageal and head and neck tumors. Overall, our findings provide novel insights into early molecular changes induced by (S)-NNN and, therefore, could contribute to the development of biomarkers for the early detection and prevention of (S)-NNN-associated oral and esophageal cancers. © 2016 Wiley Periodicals, Inc.

Radiotherapy and Immunotherapy Combinations in Non-small Cell Lung Cancer: A Promising Future?

The goal of re-programming the host immune system to target malignancy with durable anti-tumour clinical responses has been speculated for decades. In the last decade such speculation has been transformed into reality with unprecedented and durable responses to immune checkpoint inhibitors seen in solid tumours. This mini-review considers the mechanism of action of immune modulating agents and the potential for combination with radiotherapy in the treatment of non-small cell lung cancer.

Acute Malaria Induces PD1+CTLA4+ Effector T Cells with Cell-Extrinsic Suppressor Function

In acute Plasmodium falciparum (P. falciparum) malaria, the pro- and anti-inflammatory immune pathways must be delicately balanced so that the parasitemia is controlled without inducing immunopathology. An important mechanism to fine-tune T cell responses in the periphery is the induction of coinhibitory receptors such as CTLA4 and PD1. However, their role in acute infections such as P. falciparum malaria remains poorly understood. To test whether coinhibitory receptors modulate CD4+ T cell functions in malaria, blood samples were obtained from patients with acute P. falciparum malaria treated in Germany. Flow cytometric analysis showed a more frequent expression of CTLA4 and PD1 on CD4+ T cells of malaria patients than of healthy control subjects. In vitro stimulation with P. falciparum-infected red blood cells revealed a distinct population of PD1+CTLA4+CD4+ T cells that simultaneously produced IFNγ and IL10. This antigen-specific cytokine production was enhanced by blocking PD1/PDL1 and CTLA4. PD1+CTLA4+CD4+ T cells were further isolated based on surface expression of PD1 and their inhibitory function investigated in-vitro. Isolated PD1+CTLA4+CD4+ T cells suppressed the proliferation of the total CD4+ population in response to anti-CD3/28 and plasmodial antigens in a cell-extrinsic manner. The response to other specific antigens was not suppressed. Thus, acute P. falciparum malaria induces P. falciparum-specific PD1+CTLA4+CD4+ Teffector cells that coproduce IFNγ and IL10, and inhibit other CD4+ T cells. Transient induction of regulatory Teffector cells may be an important mechanism that controls T cell responses and might prevent severe inflammation in patients with malaria and potentially other acute infections.

Costimulatory and coinhibitory immune checkpoint receptors in head and neck cancer: unleashing immune responses through therapeutic combinations

Head and neck squamous cell carcinoma (HNSCC) represents a model of escape from anti-tumor immunity. The high frequency of p53 tumor suppressor loss in HNSCC leads to genomic instability and immune stimulation through the generation of neoantigens. However, the aggressive nature of HNSCC tumors and significant rates of resistance to conventional therapies highlights the ability of HNSCC to evade this immune response. Advances in understanding the role of co-stimulatory and immune checkpoint receptors in HNSCC-mediated immunosuppression lay the foundation for development of novel therapeutic approaches. This article provides an overview of these co-stimulatory and immune checkpoint pathways, as well as a review of preclinical and clinical evidence supporting the modulation of these pathways in HNSCC. Finally, the synergistic potential of combining these approaches is discussed, along with an update of current clinical trials evaluating combinations of immune-based therapies in HNSCC patients.

Stereotactic ablative radiotherapy and immunotherapy combinations: turning the future into systemic therapy?

Radiotherapy (RT) is effective at cytoreducing tumours and until relatively recently the focus in radiobiology has been on the direct effects of RT on the tumour. Increasingly, however, the effect of RT on the tumour vasculature, tumour stroma and immune system are recognized as important to the overall outcome. RT is known to lead to the induction of immunogenic cell death (ICD), which can generate tumour-specific immunity. However, systemic immunity leading to "abscopal effects" resulting in tumour shrinkage outside of the RT treatment field is rare, which is thought to be caused by the immunosuppressive nature of the tumour microenvironment. Recent advances in understanding the nature of this immunosuppression and therapeutics targeting immune checkpoints such as programmed death 1 has led to durable clinical responses in a range of cancer types including malignant melanoma and non-small-cell lung cancer. The effects of RT dose and fraction on the generation of ICD and systemic immunity are largely unknown and are currently under investigation. Stereotactic ablative radiotherapy (SABR) provides an opportunity to deliver single or hypofractionated large doses of RT and potentially increase the amount of ICD and the generation of systemic immunity. Here, we review the interplay of RT and the tumour microenvironment and the rationale for combining SABR with immunomodulatory agents to generate systemic immunity and improve outcomes.

Fractionated Radiotherapy with 3 x 8 Gy Induces Systemic Anti-Tumour Responses and Abscopal Tumour Inhibition without Modulating the Humoral Anti-Tumour Response

Accumulating evidence indicates that fractionated radiotherapy (RT) can result in distant non-irradiated (abscopal) tumour regression. Although preclinical studies indicate the importance of T cells in this infrequent phenomenon, these studies do not preclude that other immune mechanisms exhibit an addition role in the abscopal effect. We therefore addressed the question whether in addition to T cell mediated responses also humoral anti-tumour responses are modulated after fractionated RT and whether systemic dendritic cell (DC) stimulation can enhance tumour-specific antibody production. We selected the 67NR mammary carcinoma model since this tumour showed spontaneous antibody production in all tumour-bearing mice. Fractionated RT to the primary tumour was associated with a survival benefit and a delayed growth of a non-irradiated (contralateral) secondary tumour. Notably, fractionated RT did not affect anti-tumour antibody titers and the composition of the immunoglobulin (Ig) isotypes. Likewise, we demonstrated that treatment of tumour-bearing Balb/C mice with DC stimulating growth factor Flt3-L did neither modulate the magnitude nor the composition of the humoral immune response. Finally, we evaluated the immune infiltrate and Ig isotype content of the tumour tissue using flow cytometry and found no differences between treatment groups that were indicative for local antibody production. In conclusion, we demonstrate that the 67NR mammary carcinoma in Balb/C mice is associated with a pre-existing antibody response. And, we show that in tumour-bearing Balb/C mice with abscopal tumour regression such pre-existing antibody responses are not altered upon fractionated RT and/or DC stimulation with Flt3-L. Our research indicates that evaluating the humoral immune response in the setting of abscopal tumour regression is not invariably associated with therapeutic effects.

Antitumor Efficacy of Radiation plus Immunotherapy Depends upon Dendritic Cell Activation of Effector CD8+ T Cells

Tumor cells dying after cytotoxic therapy are a potential source of antigen for T-cell priming. Antigen-presenting cells (APC) can cross-present MHC I-restricted peptides after the uptake of dying cells. Depending on the nature of the surrounding environmental signals, APCs then orchestrate a spectrum of responses ranging from immune activation to inhibition. Previously, we had demonstrated that combining radiation with either agonistic monoclonal antibody (mAb) to CD40 or a systemically administered TLR7 agonist could enhance CD8 T-cell-dependent protection against syngeneic murine lymphoma models. However, it remains unknown how individual APC populations affect this antitumor immune response. Using APC depletion models, we now show that dendritic cells (DC), but not macrophages or B cells, were responsible for the generation of long-term immunologic protection following combination therapy with radiotherapy and either agonistic CD40 mAb or systemic TLR7 agonist therapy. Novel immunotherapeutic approaches that augment antigen uptake and presentation by DCs may further enhance the generation of therapeutic antitumor immune responses, leading to improved outcomes after radiotherapy. Cancer Immunol Res; 4(7); 621-30. ©2016 AACR.

Targetless T cells in cancer immunotherapy

Attention has recently focused on new cancer immunotherapy protocols aiming to activate T cell mediated anti-tumor responses. To this end, administration of antibodies that target inhibitory molecules regulating T-cell cytotoxicity has achieved impressive clinical responses, as has adoptive cell transfer (ACT) using expanded tumor infiltrating lymphocytes (TIL) or genetically modified cytotoxic T cells. However, despite clear clinical responses, only a fraction of patients respond to treatment and there is an urgent call for characterization of predictive biomarkers. CD8 positive T cells can infiltrate tumor tissues and destroy HLA class I positive tumor cells expressing the specific antigen. In fact, current progress in the field of cancer immune therapy is based on the capacity of T cells to kill cancer cells that present tumor antigen in the context on an HLA class I molecule. However, it is also well established that cancer cells are often characterized by loss or down regulation of HLA class I molecules, documented in a variety of human tumors. Consequently, immune therapy building on CD8 T cells will be futile in patients harboring HLA class-I negative or deficient cancer cells. It is therefore mandatory to explore if these important molecules for T cell cytotoxicity are expressed by cancer target cells. We have indications that different types of immunotherapy can modify the tumor microenvironment and up-regulate reduced HLA class I expression in cancer cells but only if the associated molecular mechanisms is reversible (soft). However, in case of structural (hard) aberrations causing HLA class I loss, tumor cells will not be able to recover HLA class I expression and as a consequence will escape T-cell lysis and continue to growth. Characterization of the molecular mechanism underlying the lack or downregulation of HLA class I expression, seems to be a crucial step predicting clinical responses to T cell mediated immunotherapy, and possibly aid the selection of strategies that could condition patients for response. Thus, characterization of HLA expression by cancer cells could therefore represent an important predictive marker for immunotherapy of cancer.

Improving therapeutic activity of anti-CD20 antibody therapy through immunomodulation in lymphoid malignancies

Nearly two decades ago rituximab heralded a new era in management of B cell malignancies significantly increasing response rates and survival. However, despite clear therapeutic advantage, significant numbers of patients become refractory to anti-CD20 mAb therapy, suggesting urgent improvements are required. It is now well recognized that the suppressive tumor microenvironment plays an important role in the outcome of anti-CD20 mAb therapy and that manipulation of this environment may improve the efficacy and produce long-term tumor control. The past few years have seen a surge of interest in immunomodulatory agents capable of overwriting immune suppressive networks into favorable clinical outcome. Currently, a number of such combinations with anti-CD20 mAb is under evaluation and some have produced encouraging outcomes in rituximab refractory disease. In this review, we give an outline of anti-CD20 mAbs and explore the combinations with immunomodulatory agents that enhance antitumor immunity through targeting stimulatory or inhibitory pathways and have proven potential to synergize with anti-CD20 mAb therapy. These agents, primarily mAbs, target CTLA-4, PD-1/PD-L1, and CD40.

Immune based therapy for melanoma

A few years ago therapeutic options in advanced melanoma were very limited and the prognosis was somber. Although recent progresses are far from providing a cure for advanced melanoma, yet these have kindled new hopes and searching for a cure does not seem unreasonable. Seven new medicines have been authorized in various regions of the world in the recent past in the therapy of advanced melanoma, over half of them acting by mechanisms involving the immune system of the host. The anti-CTLA-4 (cytotoxic T lymphocyte associated protein-4) ipilimumab has been followed by anti-PD1 (programmed death1) inhibitors, more effective and safer. Very recently, the first oncolytic immunotherapy, talimogene laherparepvec (T-VEC) has been authorized for placing on the market and a variety of combinations of the new therapies are currently being evaluated or considered. Besides, a plethora of other molecules and approaches, especially monoclonal antibodies, are in the preliminary phases of clinical investigation and are likely to bring new benefits for the treatment of this potentially fatal form of cancer.

Immune Checkpoint Modulation in Colorectal Cancer: What's New and What to Expect

Colorectal cancer (CRC), as one of the most prevalent types of cancer worldwide, is still a leading cause of cancer related mortality. There is an urgent need for more efficient therapies in metastatic disease. Immunotherapy, a rapidly expanding field of oncology, is designed to boost the body's natural defenses to fight cancer. Of the many approaches currently under study to improve antitumor immune responses, immune checkpoint inhibition has thus far been proven to be the most effective. This review will outline the treatments that take advantage of our growing understanding of the role of the immune system in cancer, with a particular emphasis on immune checkpoint molecules, involved in CRC pathogenesis.