CTLA-4 blockade synergizes with tumor-derived granulocyte-macrophage colony-stimulating factor for treatment of an experimental mammary carcinoma

FusionVAC22_01: a phase I clinical trial evaluating a DNAJB1-PRKACA fusion transcript-based peptide vaccine combined with immune checkpoint inhibition for fibrolamellar hepatocellular carcinoma and other tumor entities carrying the oncogenic driver fusion

The DNAJB1-PRKACA fusion transcript was identified as the oncogenic driver of tumor pathogenesis in fibrolamellar hepatocellular carcinoma (FL-HCC), also known as fibrolamellar carcinoma (FLC), as well as in other tumor entities, thus representing a broad target for novel treatment in multiple cancer entities. FL-HCC is a rare primary liver tumor with a 5-year survival rate of only 45%, which typically affects young patients with no underlying primary liver disease. Surgical resection is the only curative treatment option if no metastases are present at diagnosis. There is no standard of care for systemic therapy. Peptide-based vaccines represent a low side-effect approach relying on specific immune recognition of tumor-associated human leucocyte antigen (HLA) presented peptides. The induction (priming) of tumor-specific T-cell responses against neoepitopes derived from gene fusion transcripts by peptide-vaccination combined with expansion of the immune response and optimization of immune function within the tumor microenvironment achieved by immune-checkpoint-inhibition (ICI) has the potential to improve response rates and durability of responses in malignant diseases. The phase I clinical trial FusionVAC22_01 will enroll patients with FL-HCC or other cancer entities carrying the DNAJB1-PRKACA fusion transcript that are locally advanced or metastatic. Two doses of the DNAJB1-PRKACA fusion-based neoepitope vaccine Fusion-VAC-XS15 will be applied subcutaneously (s.c.) with a 4-week interval in combination with the anti-programmed cell death-ligand 1 (PD-L1) antibody atezolizumab starting at day 15 after the first vaccination. Anti-PD-L1 will be applied every 4 weeks until end of the 54-week treatment phase or until disease progression or other reason for study termination. Thereafter, patients will enter a 6 months follow-up period. The clinical trial reported here was approved by the Ethics Committee II of the University of Heidelberg (Medical faculty of Mannheim) and the Paul-Ehrlich-Institute (P-00540). Clinical trial results will be published in peer-reviewed journals.

Trial registration numbers

EU CT Number: 2022-502869-17-01 and ClinicalTrials.gov Registry (NCT05937295).

Targeting Histone 3 Variants Epigenetic Landscape and Inhibitory Immune Checkpoints: An Option for Paediatric Brain Tumours Therapy

Despite little progress in survival rates with regular therapies, which do not provide complete care for curing pediatric brain tumors (PBTs), there is an urgent need for novel strategies to overcome the toxic effects of conventional therapies to treat PBTs. The co-inhibitory immune checkpoint molecules, e.g., CTLA-4, PD-1/PD-L1, etc., and epigenetic alterations in histone variants, e.g., H3K27me3 that help in immune evasion at tumor microenvironment have not gained much attention in PBTs treatment. However, key epigenetic mechanistic alterations, such as acetylation, methylation, phosphorylation, sumoylation, poly (ADP)-ribosylation, and ubiquitination in histone protein, are greatly acknowledged. The crucial checkpoints in pediatric brain tumors are cytotoxic T lymphocyte antigen-4 (CTLA-4), programmed cell death protein-1 (PD-1) and programmed death-ligand 1 (PDL1), OX-2 membrane glycoprotein (CD200), and indoleamine 2,3-dioxygenase (IDO). This review covers the state of knowledge on the role of multiple co-inhibitory immunological checkpoint proteins and histone epigenetic alterations in different cancers. We further discuss the processes behind these checkpoints, cell signalling, the current scenario of clinical and preclinical research and potential futuristic opportunities for immunotherapies in the treatment of pediatric brain tumors. Conclusively, this article further discusses the possibilities of these interventions to be used for better therapy options.

Resistance to immune checkpoint therapies by tumour-induced T-cell desertification and exclusion: key mechanisms, prognostication and new therapeutic opportunities

Immune checkpoint therapies (ICT) can reinvigorate the effector functions of anti-tumour T cells, improving cancer patient outcomes. Anti-tumour T cells are initially formed during their first contact (priming) with tumour antigens by antigen-presenting cells (APCs). Unfortunately, many patients are refractory to ICT because their tumours are considered to be 'cold' tumours-i.e., they do not allow the generation of T cells (so-called 'desert' tumours) or the infiltration of existing anti-tumour T cells (T-cell-excluded tumours). Desert tumours disturb antigen processing and priming of T cells by targeting APCs with suppressive tumour factors derived from their genetic instabilities. In contrast, T-cell-excluded tumours are characterised by blocking effective anti-tumour T lymphocytes infiltrating cancer masses by obstacles, such as fibrosis and tumour-cell-induced immunosuppression. This review delves into critical mechanisms by which cancer cells induce T-cell 'desertification' and 'exclusion' in ICT refractory tumours. Filling the gaps in our knowledge regarding these pro-tumoral mechanisms will aid researchers in developing novel class immunotherapies that aim at restoring T-cell generation with more efficient priming by APCs and leukocyte tumour trafficking. Such developments are expected to unleash the clinical benefit of ICT in refractory patients.

Phenotypes and Functions of Human Dendritic Cell Subsets in the Tumor Microenvironment

Dendritic cells (DCs) play a key role in the antitumor immunity, as they are at the interface of innate and adaptive immunity. This important task can only be performed thanks to the broad range of mechanisms that DCs can perform to activate other immune cells. As DCs are well known for their outstanding capacity to prime and activate T cells through antigen presentation, DCs were intensively investigated during the past decades. Numerous studies have identified new DC subsets, leading to a large variety of subsets commonly separated into cDC1, cDC2, pDCs, mature DCs, Langerhans cells, monocyte-derived DCs, Axl-DCs, and several other subsets. Here, we review the specific phenotypes, functions, and localization within the tumor microenvironment (TME) of human DC subsets thanks to flow cytometry and immunofluorescence but also with the help of high-output technologies such as single-cell RNA sequencing and imaging mass cytometry (IMC).

Management of Regional Lymph Nodes in Head and Neck Melanoma

The utilization of sentinel lymph node (SLN) biopsy has transformed the workup and staging of intermediate-thickness cutaneous melanomas. SLN biopsy, performed at the time of primary tumor excision, accurately maps lymph nodes at risk of harboring occult metastatic deposits from head and neck cutaneous melanomas and represents the current standard of care. Completion lymphadenectomy identifies additional tumor in 12% to 24% of SLN biopsy positive cases but does not affect melanoma-specific survival.

AKT Isoforms in the Immune Response in Cancer

AKT is a protein kinase that exists in three isoforms: AKT1, AKT2, and AKT3. Though similar in structure, these isoforms display different effects. AKT is activated downstream of PI3K, and together, this signaling pathway helps regulate cellular processes including cell growth, proliferation, metabolism, survival, and apoptosis. Disruption in these pathways has been associated with disorders including cardiovascular diseases, developmental disorders, inflammatory responses, autoimmune diseases, neurologic disorders, type 2 diabetes, and several cancers. In cancer, deregulation in the PI3K/AKT pathway can be manifested as tumorigenesis, pathological angiogenesis, and metastasis. Increased activity has been correlated with tumor progression and resistance to cancer treatments. Recent studies have suggested that inhibition of the PI3K/AKT pathway plays a significant role in the development, expansion, and proliferation of cells of the immune system. Additionally, AKT has been found to play an important role in differentiating regulatory T cells, activating B cells, and augmenting tumor immunosurveillance. This emphasizes AKT as a potential target for inhibition in cancer therapy. This chapter reviews AKT structure and regulation, its different isoforms, its role in immune cells, and its modulation in oncotherapy.

Sargramostim and immune checkpoint inhibitors: combinatorial therapeutic studies in metastatic melanoma

The use of immune checkpoint inhibitors in patients with metastatic melanoma generates clinical benefit, including improved survival. Yet disease resistance and immune-related adverse events persist as unmet needs. Sargramostim, a yeast-derived recombinant human GM-CSF, has shown clinical activity against diverse solid tumors, including metastatic melanoma. Here we review the use of sargramostim for treatment of advanced melanoma. Potential sargramostim applications in melanoma draw on the unique ability of GM-CSF to link innate and adaptive immune responses. We review preclinical and translational data describing the mechanism of action of sargramostim and synergy with immune checkpoint inhibitors to enhance efficacy and reduce treatment-related toxicity.

Safety and Efficacy of Personalized Cancer Vaccines in Combination With Immune Checkpoint Inhibitors in Cancer Treatment

Cancer immunotherapy can induce sustained responses in patients with cancers in a broad range of tissues, however, these treatments require the optimized combined therapeutic strategies. Despite immune checkpoint inhibitors (ICIs) have lasting clinical benefit, researchers are trying to combine them with other treatment modalities, and among them the combination with personalized cancer vaccines is attractive. Neoantigens, arising from mutations in cancer cells, can elicit strong immune response without central tolerance and out-target effects, which is a truly personalized method. Growing studies show that the combination can elevate the antitumor efficacy with acceptable safety and minimal additional toxicity compared with single agent vaccine or ICI. Herein, we have searched these preclinical and clinical trials and summarized safety and efficacy of personalized cancer vaccines combined with ICIs in several malignancies. Meanwhile, we discuss the rationale of the combination and future challenges.

Immune checkpoint inhibition in classical hodgkin lymphoma

Introduction: Hodgkin lymphoma (HL) accounts for 10% of lymphoma cases every year. HL is often curable by conventional chemotherapy and radiotherapy. However, in case of relapsed or refractory HL (r/r HL) after autologous hematopoietic stem cell transplantation (ASCT), few treatment options are currently available. Blockade of the immune checkpoint receptors, programmed death receptor-1 (PD-1), or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) expressed on T-cells, and their ligands expressed on tumor-associated antigen-presenting cells (APCs), and Hodgkin and Reed/Sternberg (HRS) cells can remove inhibitory signals from anti-tumor T cells. Checkpoint blockade using monoclonal antibodies could be a potential treatment. Nivolumab and pembrolizumab are approved antibodies for the treatment of r/r HL.Areas covered: This paper provides a comprehensive discussion of checkpoint inhibitors in HL treatment, including the most important clinical trials with mono- or combination therapies as a first or second-line treatment of HL.Expert opinion: Relatively high response rates and an acceptable safety profile of checkpoint inhibitors make them an effective therapy for HL. The combination of checkpoint inhibition with other conventional cancer treatments and identifying the mechanisms responsible for resistance to checkpoint inhibition may improve the efficacy and safety of this immunotherapy, and enhance patient quality of life.

Therapeutic Targeting of the Tumor Microenvironment

Strategies to therapeutically target the tumor microenvironment (TME) have emerged as a promising approach for cancer treatment in recent years due to the critical roles of the TME in regulating tumor progression and modulating response to standard-of-care therapies. Here, we summarize the current knowledge regarding the most advanced TME-directed therapies, which have either been clinically approved or are currently being evaluated in trials, including immunotherapies, antiangiogenic drugs, and treatments directed against cancer-associated fibroblasts and the extracellular matrix. We also discuss some of the challenges associated with TME therapies, and future perspectives in this evolving field. SIGNIFICANCE: This review provides a comprehensive analysis of the current therapies targeting the TME, combining a discussion of the underlying basic biology with clinical evaluation of different therapeutic approaches, and highlighting the challenges and future perspectives.

Fine-Tuning the Tumour Microenvironment: Current Perspectives on the Mechanisms of Tumour Immunosuppression

Immunotherapy has revolutionised the treatment of cancers by harnessing the power of the immune system to eradicate malignant tissue. However, it is well recognised that some cancers are highly resistant to these therapies, which is in part attributed to the immunosuppressive landscape of the tumour microenvironment (TME). The contexture of the TME is highly heterogeneous and contains a complex architecture of immune, stromal, vascular and tumour cells in addition to acellular components such as the extracellular matrix. While understanding the dynamics of the TME has been instrumental in predicting durable responses to immunotherapy and developing new treatment strategies, recent evidence challenges the fundamental paradigms of how tumours can effectively subvert immunosurveillance. Here, we discuss the various immunosuppressive features of the TME and how fine-tuning these mechanisms, rather than ablating them completely, may result in a more comprehensive and balanced anti-tumour response.

Immune Checkpoint Inhibitors for the Treatment of Cancer: Clinical Impact and Mechanisms of Response and Resistance

Immune checkpoint inhibitors (ICIs) have made an indelible mark in the field of cancer immunotherapy. Starting with the approval of anti-cytotoxic T lymphocyte-associated protein 4 (anti-CTLA-4) for advanced-stage melanoma in 2011, ICIs-which now also include antibodies against programmed cell death 1 (PD-1) and its ligand (PD-L1)-quickly gained US Food and Drug Administration approval for the treatment of a wide array of cancer types, demonstrating unprecedented extension of patient survival. However, despite the success of ICIs, resistance to these agents restricts the number of patients able to achieve durable responses, and immune-related adverse events complicate treatment. Thus, a better understanding of the requirements for an effective and safe antitumor immune response following ICI therapy is needed. Studies of both tumoral and systemic changes in the immune system following ICI therapy have yielded insight into the basis for both efficacy and resistance. Ultimately, by building on these insights, researchers should be able to combine ICIs with other agents, or design new immunotherapies, to achieve broader and more durable efficacy as well as greater safety. Here, we review the history and clinical utility of ICIs, the mechanisms of resistance to therapy, and local and systemic immune cell changes associated with outcome.

Principles of Immunotherapy in Non-Small Cell Lung Cancer

Immunotherapy has transformed the treatment of many tumors. Robust data demonstrating improved overall survival and progression-free survival in patients treated with monoclonal antibodies have established immune checkpoint inhibitors as standard of care in stages III and IV non-small cell lung cancer. Nivolumab is effective in previously treated patients with metastatic non-small cell lung cancer. Pembrolizumab and atezolizumab are approved as monotherapy and in combination with other therapies. Ongoing trials investigate the potential role of immunotherapy in earlier disease settings. Identifying predictive biomarkers of response will further amplify the impact of immune checkpoint inhibitors in the treatment of non-small cell lung cancer.

The Role of Neoadjuvant Therapy in Melanoma

PURPOSE OF REVIEW

Neoadjuvant therapy in melanoma is an area of active investigation with numerous completed and ongoing trials studying a variety of therapeutic interventions utilizing diverse designs. Here, we review completed and ongoing neoadjuvant trials in melanoma, discuss endpoint assessment, and highlight biomarker development in this context.

RECENT FINDINGS

High-risk resectable melanoma with clinically detectable lymph node (LN) with or without in-transit and/or satellite metastases represent ~ 20% of melanoma patients and have a high risk of relapse despite definitive surgery. Adjuvant therapy with anti-PD-1 immunotherapy or BRAF/MEK-targeted therapy has improved relapse-free survival (RFS) and overall survival (OS) in large phase III trials and is approved for this indication. However, despite surgery and adjuvant therapy, many patients relapse and/or experience treatment-related toxicity, underscoring the need to identify and understand mechanisms of response and resistance. In melanoma, neoadjuvant therapy is an active area of research with numerous completed and ongoing trials utilizing FDA-approved and novel agents with intriguing results. Neoadjuvant therapy for regionally metastatic disease is an established standard in multiple cancers, where it has been shown to improve operability, facilitate biomarker development, and even is a registrational endpoint for drug development in breast cancer. Recently, a spate of neoadjuvant studies in melanoma has looked at a swathe of agents with promising clinical and biomarker results. Coordinated efforts are underway to translate these findings to earlier stage disease while prioritizing the evaluation of new strategies in unresectable disease.

Safety, immunogenicity, and clinical efficacy of durvalumab in combination with folate receptor alpha vaccine TPIV200 in patients with advanced ovarian cancer: a phase II trial

BACKGROUND

Immune checkpoint inhibitors (ICIs) to date have demonstrated limited activity in advanced ovarian cancer (OC). Folate receptor alpha (FRα) is overexpressed in the majority of OCs and presents an attractive target for a combination immunotherapy to potentially overcome resistance to ICI in OCs. The current study sought to examine clinical and immunologic responses to TPIV200, a multiepitope FRα vaccine administered with programmed death ligand 1 (PD-L1) inhibitor durvalumab in patients with advanced platinum-resistant OC.

METHODS

Following Simon two-stage phase II trial design, 27 patients were enrolled. Treatment was administered in 28-day cycles (intradermal TPIV200 and granulocyte-macrophage colony-stimulating factor (GM-CSF) for 6 cycles and intravenous durvalumab for 12 cycles). Primary endpoints included overall response rate and progression-free survival at 24 weeks. Translational parameters focused on tumor microenvironment, PD-L1 and FRα expression, and peripheral vaccine-specific immune responses.

RESULTS

Treatment was well tolerated, with related grade 3 toxicity rate of 18.5%. Increased T cell responses to the majority of peptides were observed in all patients at 6 weeks (p<0.0001). There was one unconfirmed partial response (3.7%) and nine patients had stable disease (33.3%). Clinical benefit was not associated with baseline FRα or PD-L1 expression. One patient with prolonged clinical benefit demonstrated loss of FRα expression and upregulation of PD-L1 in a progressing lesion. Despite the low overall response rate, the median overall survival was 21 months (13.5-∞), with evidence of benefit from postimmunotherapy regimens.

CONCLUSIONS

Combination of TPIV200 and durvalumab was safe and elicited robust FRα-specific T cell responses in all patients. Unexpectedly durable survival in this heavily pretreated population highlights the need to investigate the impact of FRα vaccination on the OC biology post-treatment.

CCL5 mediates CD40-driven CD4+ T cell tumor infiltration and immunity

The role CD4+ T cells play in tumor immunity is less well appreciated than the cytotoxic role of CD8+ T cells. Despite clear evidence for CD4+ T cell dependency across multiple immunotherapies, the mechanisms by which CD4+ T cells infiltrate tumors remain poorly understood. Prior studies by our group have shown in a mouse model of pancreatic cancer that systemic activation of the cell surface TNF superfamily member CD40 drives T cell infiltration into tumors and, in combination with immune checkpoint blockade, leads to durable tumor regressions and cures that depend on both CD8+ and CD4+ T cells. Here, we used single-cell transcriptomics to examine the tumor microenvironment following treatment with agonist CD40 antibody with or without immune checkpoint blockade. We show that intratumor myeloid cells produce the chemokine CCL5 in response to CD40 agonist and that CCL5 mediates an influx of CD4+ T cells into the tumor microenvironment. Disruption of CCL5 genetically or pharmacologically mitigates the influx of CD4+ but not CD8+ T cells into tumors and blunts the therapeutic efficacy of immunotherapy. These findings highlight a previously unappreciated role for CCL5 in selectively mediating CD4+ T cell tumor infiltration in response to effective immunotherapy.

microRNAs involved in T-cell development, selection, activation, and hemostasis

MicroRNAs (miRNAs) characterized by small, noncoding RNAs have a fundamental role in the regulation of gene expression at the post-transcriptional level. Additionally, miRNAs have recently been identified as potential regulators of various genes involved in the pathogenesis of the autoimmune and inflammatory disease. So far, the interaction between miRNAs and T lymphocytes in the immune response as a new and significant topic has not been emphasized substantially. The role of miRNAs in different biological processes including apoptosis, immune checkpoints and the activation of immune cells is still unclear. Aberrant miRNA expression profile affects various aspects of T-cell function. Accordingly, in this literature review, we summarized the role of significant miRNAs in T-cell development processes. Consequently, we demonstrated precise mechanisms that candidate miRNAs interfere in Immune response mediated by different types of T cells. We believe that a good understanding of the interaction between miRNAs and immune response contributes to the new therapeutic strategies in relation to disease with an immunological origin.

Immune checkpoint inhibitors: a narrative review of considerations for the anaesthesiologist

Immunotherapy has revolutionised the treatment of oncologic malignancies. Immune checkpoint inhibitors represent a new class of immunotherapy drugs. Although these drugs show promise, they are associated with immune-related adverse reactions. An increasing number of patients who undergo surgery will have had treatment with immune checkpoint inhibitors. In this narrative review article, we discuss their mechanism of action, therapeutic effects, pertinent toxicities, and address specific perioperative considerations for patients treated with immune checkpoint inhibitors.

Immunosurveillance and Immunoediting of Lung Cancer: Current Perspectives and Challenges

The immune system plays a dual role in tumor evolution-it can identify and control nascent tumor cells in a process called immunosurveillance and can promote tumor progression through immunosuppression via various mechanisms. Thus, bilateral host-protective and tumor-promoting actions of immunity are integrated as cancer immunoediting. In this decade, immune checkpoint inhibitors, specifically programmed cell death 1 (PD-1) pathway inhibitors, have changed the treatment paradigm of advanced non-small cell lung cancer (NSCLC). These agents are approved for the treatment of patients with NSCLC and demonstrate impressive clinical activity and durable responses in some patients. However, for many NSCLC patients, the efficacy of immune checkpoint inhibitors is limited. To optimize the full utility of the immune system for eradicating cancer, a broader understanding of cancer immunosurveillance and immunoediting is essential. In this review, we discuss the fundamental knowledge of the phenomena and provide an overview of the next-generation immunotherapies in the pipeline.

A guide to cancer immunotherapy: from T cell basic science to clinical practice

The T lymphocyte, especially its capacity for antigen-directed cytotoxicity, has become a central focus for engaging the immune system in the fight against cancer. Basic science discoveries elucidating the molecular and cellular biology of the T cell have led to new strategies in this fight, including checkpoint blockade, adoptive cellular therapy and cancer vaccinology. This area of immunological research has been highly active for the past 50 years and is now enjoying unprecedented bench-to-bedside clinical success. Here, we provide a comprehensive historical and biological perspective regarding the advent and clinical implementation of cancer immunotherapeutics, with an emphasis on the fundamental importance of T lymphocyte regulation. We highlight clinical trials that demonstrate therapeutic efficacy and toxicities associated with each class of drug. Finally, we summarize emerging therapies and emphasize the yet to be elucidated questions and future promise within the field of cancer immunotherapy.

Immunological Targets for Immunotherapy: Inhibitory T Cell Receptors

Tumor development is characterized by the accumulation of mutational and epigenetic changes that transform normal cells and survival pathways into self-sustaining cells capable of untrammeled growth. Although multiple modalities including surgery, radiation, and chemotherapy are available for the treatment of cancer, the benefits conferred are often limited. The immune system is capable of specific, durable, and adaptable responses. However, cancers hijack immune mechanisms such as negative regulatory checkpoints that have evolved to limit inflammatory and immune responses to thwart effective antitumor immunity. The development of monoclonal antibodies against inhibitory receptors expressed by immune cells has produced durable responses in a broad array of advanced malignancies and heralded a new dawn in the cancer armamentarium. However, these remarkable responses are limited to a minority of patients and indications, highlighting the need for more effective and novel approaches. Preclinical and clinical studies with immune checkpoint blockade are exploring the therapeutic potential antibody-based therapy targeting multiple inhibitory receptors. In this chapter, we discuss the current understanding of the structure, ligand specificities, function, and signaling activities of various inhibitory receptors. Additionally, we discuss the current development status of various immune checkpoint inhibitors targeting these negative immune receptors and highlight conceptual gaps in knowledge.

Macrophage-Mediated Subversion of Anti-Tumour Immunity

Despite the incredible clinical benefits obtained by the use of immune checkpoint blockers (ICBs), resistance is still common for many types of cancer. Central for ICBs to work is activation and infiltration of cytotoxic CD8+ T cells following tumour-antigen recognition. However, it is now accepted that even in the case of immunogenic tumours, the effector functions of CD8+ T cells are highly compromised by the presence of an immunosuppressive tumour microenvironment (TME) at the tumour site. Tumour-associated macrophages (TAMs) are among the most abundant non-malignant stromal cell types within the TME and they are crucial drivers of tumour progression, metastasis and resistance to therapy. TAMs are able to regulate either directly or indirectly various aspects of tumour immunity, including T cell recruitment and functions. In this review we discuss the mechanisms by which TAMs subvert CD8+ T cell immune surveillance and how their targeting in combination with ICBs represents a very powerful therapeutic strategy.

New Hope for Therapeutic Cancer Vaccines in the Era of Immune Checkpoint Modulation

The driver and passenger mutations accumulated in the process of malignant transformation offer an adequate spectrum of immune visible alterations to the cellular proteome and resulting peptidome to render these cancers targetable-and, in theory, rejectable-by the host T cell immune response. In addition, cancers often overexpress tissue-specific and developmental antigens to which immune tolerance is incomplete. Sometimes, virally transferred oncogenes drive malignant transformation and remain expressed throughout the cancer. Despite this state of antigenic sufficiency, cancer grows progressively and overcomes all efforts of the host immune system to contain it. While therapeutic cancer vaccination can mobilize high frequencies of tumor-specific T cells, these responses remain subject to intratumoral attenuation. Antibody modulation of T cell function through checkpoint blockade or costimulatory activation can restore survival, proliferation, and effector function to these tumor-infiltrating T cells and convert otherwise subtherapeutic vaccines into potentially curative cancer immunotherapeutics.

A CD40 Agonist and PD-1 Antagonist Antibody Reprogram the Microenvironment of Nonimmunogenic Tumors to Allow T-cell-Mediated Anticancer Activity

In cancers with tumor-infiltrating lymphocytes (TILs), monoclonal antibodies (mAbs) that block immune checkpoints such as CTLA-4 and PD-1/PD-L1 promote antitumor T-cell immunity. Unfortunately, most cancers fail to respond to single-agent immunotherapies. T regulatory cells, myeloid derived suppressor cells (MDSCs), and extensive stromal networks within the tumor microenvironment (TME) dampen antitumor immune responses by preventing T-cell infiltration and/or activation. Few studies have explored combinations of immune-checkpoint antibodies that target multiple suppressive cell populations within the TME, and fewer have studied the combinations of both agonist and antagonist mAbs on changes within the TME. Here, we test the hypothesis that combining a T-cell-inducing vaccine with both a PD-1 antagonist and CD40 agonist mAbs (triple therapy) will induce T-cell priming and TIL activation in mouse models of nonimmunogenic solid malignancies. In an orthotopic breast cancer model and both subcutaneous and metastatic pancreatic cancer mouse models, only triple therapy was able to eradicate most tumors. The survival benefit was accompanied by significant tumor infiltration of IFNγ-, Granzyme B-, and TNFα-secreting effector T cells. Further characterization of immune populations was carried out by high-dimensional flow-cytometric clustering analysis and visualized by t-distributed stochastic neighbor embedding (t-SNE). Triple therapy also resulted in increased infiltration of dendritic cells, maturation of antigen-presenting cells, and a significant decrease in granulocytic MDSCs. These studies reveal that combination CD40 agonist and PD-1 antagonist mAbs reprogram immune resistant tumors in favor of antitumor immunity.

Dendritic Cells and CD8 T Cell Immunity in Tumor Microenvironment

Dendritic cells (DCs) play a central role in the regulation of the balance between CD8 T cell immunity vs. tolerance to tumor antigens. Cross-priming, a process which DCs activate CD8 T cells by cross-presenting exogenous antigens, plays a critical role in generating anti-tumor CD8 T cell immunity. However, there are compelling evidences now that the tumor microenvironment (TME)-mediated suppression and modulation of tumor-infiltrated DCs (TIDCs) impair their function in initiating potent anti-tumor immunity and even promote tumor progression. Thus, DC-mediated cross-presentation of tumor antigens in tumor-bearing hosts often induces T cell tolerance instead of immunity. As tumor-induced immunosuppression remains one of the major hurdles for cancer immunotherapy, understanding how DCs regulate anti-tumor CD8 T cell immunity in particular within TME has been under intensive investigation. Recent reports on the Batf3-dependent type 1 conventional DCs (cDC1s) in anti-tumor immunity have greatly advanced our understanding on the interplay of DCs and CD8 T cells in the TME, highlighted by the critical role of CD103⁺ cDC1s in the cross-priming of tumor antigen-specific CD8 T cells. In this review, we will discuss recent advances in anti-tumor CD8 T cell cross-priming by CD103⁺ cDC1s in TME, and share perspective on future directions including therapeutic applications and memory CD8 T cell responses.

Immune checkpoint Ab enhances the antigen-specific anti-tumor effects by modulating both dendritic cells and regulatory T lymphocytes

We determined the anti-tumor effects and possible mechanisms of an antigen-specific DNA vaccine combined with PD-1 or CTLA-4 blockade. Using the HPV16 E6/E7⁺ syngeneic mouse tumor model, we investigated whether anti-CTLA-4 antibody (Ab) or anti-PD-1 Ab increases the antigen-specific anti-tumor effects and immune response induced by CTGF/E7 chimeric DNA vaccine and the possible mechanisms. Anti-PD-1 Ab or anti-CTLA-4 Ab combined with E7-specific DNA vaccine generated more potent antigen-specific immunity, including anti-E7 Abs and the number and cytotoxic activity of E7-specific cytotoxic CD8⁺ T lymphocytes, and anti-tumor effects than E7-specific DNA vaccine alone. In addition, the number of systemic and intratumoral Tregs was lower with the anti-PD-1 or anti-CTLA-4 Ab and E7-specific DNA vaccine. Furthermore, anti-PD-1 and anti-CTLA-4 Abs could enhance the maturation and abilities of intratumoral DCs to activate E7-specific cytotoxic CD8⁺ T cells. Immune checkpoint blockade overcomes the immunosuppressive status of the tumor-microenvironment to enhance the antigen-specific immunity and anti-tumor effects generated by an antigen-specific DNA vaccine. Antigen-specific immunotherapy combined with immune checkpoint blockade can be a novel strategy in clinical cancer therapy.

Re-induction using whole cell melanoma vaccine genetically modified to melanoma stem cells-like beyond recurrence extends long term survival of high risk resected patients - updated results

BACKGROUND

AGI-101H is an allogeneic gene modified whole cell therapeutic melanoma vaccine, evaluated in over 400 melanoma patients in the adjuvant and therapeutic settings. We present updated long-term survival results from two single-arm, phase II adjuvant trials (Trial 3 and Trial 5) with the focus on treatment beyond recurrence of the disease.

METHODS

Patients with resected high-risk melanoma (stage IIIB-IV) were enrolled to Trial 3 (n = 99) and Trial 5 (n = 97). The primary endpoint was disease-free survival (DFS), and the secondary was overall survival (OS). In the induction phase, the vaccine was administered every 2 weeks (eight times), followed by the maintenance phase every month until progression. At progression, maintenance was continued or re-induction was applied with or without surgery.

RESULTS

In Trial 3, the 10-year DFS was equal to 33.0% overall and to 52.4, 25.0, and 8.7% for stage IIIB, IIIC, and stage IV patients, respectively. In Trial 5, the overall 10-year DFS was equal to 24.2%, and to 37.5, 18.0, and 17.6% for stage IIIB, IIIC, and stage IV patients, respectively. In Trial 3, the 10-year OS was equal to 42.3% overall, and to 59.5, 37.5, and 17.4% for stage IIIB, IIIC, and stage IV patients, respectively. In Trial 5, the 10-year OS was equal to 34.3% overall and to 46.9, 28.0, and 29.4% for stage IIIB, IIIC, and stage IV patients, respectively. Among the 65 patients of Trial 3 who developed progression, 43 received re-induction with (n = 22) or without (n = 21) surgery. Two patients received surgery without re-induction. All the 22 progressing patients, who did not receive re-induction, died. Among the 75 patients of Trial 5 who experienced progression, 39 received re-induction with (n = 21) or without (n = 18) surgery. Among the 36 progressing patients who did not receive the re-induction, 35 died. Surgery and re-induction reduced (independently) the increase of mortality after progression in both trials, with the effect of re-induction reaching statistical significance in Trial 5.

CONCLUSIONS

Vaccination beyond recurrence of the disease with additional re-induction combined with surgery or alone increased long term survival of melanoma patients. However, further studies on larger patient cohorts are required.

TRIAL REGISTRATION

Central Evidence of Clinical Trials (EudraCT Number 2008-003373-40 ).

Prostate cancer: updates on current strategies for screening, diagnosis and clinical implications of treatment modalities

Prostate cancer is the most common cancer in men by way of diagnosis and a leading cause of cancer-related deaths. Early detection and intervention remains key to its optimum clinical management. This review provides the most updated information on the recent methods of prostate cancer screening, imaging and treatment modalities. Wherever possible, clinical trial data has been supplemented to provide a comprehensive overview of current prostate cancer research and development. Considering the recent success of immunotherapy in prostate cancer, we discuss cell, DNA and viruses based, as well as combinatorial immunotherapeutic strategies in detail. Furthermore, the potential of nanotechnology is increasingly being realized, especially in prostate cancer research, and we provide an overview of nanotechnology-based strategies, with special emphasis on nanotheranostics and multifunctional nanoconstructs. Understanding these recent developments is critical to the design of future therapeutic strategies to counter prostate cancer.

Talimogene Laherparepvec (TVEC) for the Treatment of Advanced Melanoma: A Single-Institution Experience

BACKGROUND

Talimogene laherparepvec (TVEC) is an oncolytic herpes virus used as intralesional therapy for patients with unresectable stage IIIB through IV melanoma. We reviewed the standard of care treatment of TVEC at a single institution.

METHODS

All patients treated with TVEC for advanced melanoma were retrospectively evaluated from 2015 to 2018. Patient demographics, clinicopathologic characteristics, treatment response, and toxicity were reviewed.

RESULTS

Twenty-seven patients underwent therapy with TVEC. Median age was 75 years, and 63% of patients were female. Seventeen (63.0%) patients underwent injections on the lower extremity, four (14.8%) on the upper extremity, four (14.8%) on the head and neck, and two (7.4%) on the trunk. Median number of injections was five. Median follow-up was 8.6 months. Of the 27 patients, 23 patients met the criteria for response analysis with at least 8 weeks follow-up. Ten (43.5%) patients experienced a complete response (CR), three (13.1%) experienced a partial response (PR), and five (21.7%) had stable disease (SD) for an overall response rate of 56.5% (CR + PR) and a disease control rate of 78.3% (CR + PR + SD). Adverse events were mostly limited to mild constitutional symptoms within 48 h of injection. Two patients developed cellulitis treated with oral antibiotics, and one patient underwent excision of a lesion for ulceration and bleeding during therapy.

DISCUSSION

TVEC is an effective and well-tolerated intralesional therapy for patients with unresectable stage IIIB through IV melanoma. A CR was achieved in almost half of patients treated. Disease control is seen in the vast majority.

On the Road to Immunotherapy-Prospects for Treating Head and Neck Cancers With Checkpoint Inhibitor Antibodies

Head and neck cancers (HNC) represent a heterogeneous cluster of aggressive malignancies that account for 3% of all cancer cases in the UK. HNC is increasing in frequency particularly in the developing world, which is related to changes in risk factors. Unfortunately, the mortality rate is high, which is chiefly attributed to late diagnosis at stages where traditional treatments fail. Cancer immunotherapy has achieved great successes in anti-tumor therapy. Checkpoint inhibitor (CI) antibodies enhance anti-tumor activity by blocking inhibitory receptors to drive tumor-specific T and NK cell effector responses. Since their introduction in 2011, CI antibodies have been approved for many cancer types including HNC. Here, we examine the development of CI therapies and look forward to future developments for treatment of HNC with CI therapies.

Cblb-deficient T cells are less susceptible to PD-L1-mediated inhibition

Modulation of the immune system for the treatment of primary and metastatic tumors has been a goal of cancer research for many years. The E3 ubiquitin ligase Cbl-b has been established as an intracellular checkpoint that limits T cell activation, critically contributing to the maintenance of self-tolerance. Furthermore, it has been shown that Cblb deficiency enhances T cell effector functions towards tumors. Blockade of the immune checkpoints CTLA-4 and PD-1/PD-L1 has recently emerged as a promising strategy in the development of effective cancer immune therapies. Therefore, we explored the concept of targeting different checkpoints concomitantly. Interestingly, we observed that CTLA-4 but not PD-L1 based immunotherapy selectively enhanced the anti-tumor phenotype of Cblb-deficient mice. In agreement with the in vivo results, in vitro experiments showed that Cblb^−/− T cells were less susceptible to PD-L1-mediated suppression of T cell proliferation and IFNγ secretion. Taken together, our findings reveal a so far unappreciated function of Cbl-b in the regulation of PD-1 signaling in murine T cells.

Current challenges for cancer vaccine adjuvant development

INTRODUCTION

Although much progress has been made in the last decade(s) toward development of effective cancer vaccines, there are still important obstacles to therapeutic successes. New generations of cancer vaccines will benefit from a combination adjuvant approach that targets multiple branches of the immune response.

AREAS COVERED

Herein we describe how combinatorial adjuvant strategies can help overcome important obstacles to cancer vaccine development, including antigen immunogenicity and tumor immune suppression. Tumor antigens may be both tolerogenic and may utilize active mechanisms to suppress host immunity, including downregulation of MHC molecules to evade recognition and upregulation of immune inhibitory receptors, to subvert an effective immune response. The current cancer vaccine literature was surveyed to identify advancements in the understanding of the biological mechanisms underlying poor antigen immunogenicity and tumor immune evasion, as well as adjuvant strategies designed to overcome them.

EXPERT COMMENTARY

Poor immunogenicity of tumor antigens and tumor immune evasion mechanisms make the design of cancer vaccines challenging. Growing understanding of the tumor microenvironment and associated immune responses indicate the importance of augmenting not only the effector response, but also overcoming the endogenous regulatory response and tumor evasion mechanisms. Therefore, new vaccines will benefit from multi-adjuvanted approaches that simultaneously stimulate immunity while preventing inhibition.

Pediatric Cancer Immunotherapy: Opportunities and Challenges

Cancer immunotherapies, widely heralded as transformational for many adult cancer patients, are becoming viable options for selected subsets of pediatric cancer patients. Many therapies are currently being investigated, from immunomodulatory agents to adoptive cell therapy, bispecific T-cell engagers, oncolytic virotherapy, and checkpoint inhibition. One of the most exciting immunotherapies recently FDA approved is the use of CD19 chimeric antigen receptor T cells for pre-B-cell acute lymphoblastic leukemia. With this approval and others, immunotherapy for pediatric cancers is gaining traction. One of the caveats to many of these immunotherapies is the challenge of predictive biomarkers; determining which patients will respond to a given therapy is not yet possible. Much research is being focused on which biomarkers will be predictive and prognostic for these patients. Despite many benefits of immunotherapy, including less long-term side effects, some treatments are fraught with immediate side effects that range from mild to severe, although most are manageable. With few downsides and the potential for disease cures, immunotherapy in the pediatric population has the potential to move to the front-line of therapeutic options.

Improved Anti-Treg Vaccination Targeting Foxp3 Efficiently Decreases Regulatory T Cells in Mice

INTRODUCTION

The critical role of regulatory T (Treg) cells in dampening immune responses against tumor cells is apparent. Therefore, several methods have been introduced for eliminating Treg. Among them, inducing immune responses against Treg cells expressing Foxp3 transcription factor is a hopeful approach to decrease the frequency of Tregs. In current study, we used the chimeric FoxP3-Fc(IgG) fusion construct/protein to effectively stimulate the immune responses against Treg cells.

MATERIALS AND METHODS

Previously constructed FoxP3-Fc(IgG) DNA vaccine and its protein counterpart were injected into C57BL/6 mice in a prime/boost regimen. After 2 weeks, the mice were killed to measure the frequency of Tregs in their spleens, as well as analyze their specific cytokine production, T-cell proliferation, and CD8 T-cell cytotoxicity against FoxP3 protein.

RESULTS

FACS analysis of FoxP3 CD4 cells in splenocytes revealed the efficiency of FoxP3 DNA-prime protein-boost strategy to decrease the Treg cells and further showed considerable superiority of Fc(IgG) fusion strategy. This significant reduction in Treg frequency was also concomitant with higher FoxP3-specific CTL and Th1 responses in FoxP3-Fc vaccinated animals.

CONCLUSIONS

Prime/boost vaccination against FoxP3 in addition to enhanced antigen presentation by means of Fc fusion strategy could be successfully considered for Treg depletion studies. Validity of this approach should be experimentally tested in preclinical tumor models.

Molecular adjuvants that modulate regulatory T cell function in vaccination: A critical appraisal

Adjuvants are substances used to enhance the efficacy of vaccines. They influence the magnitude and alter the quality of the adaptive immune response to vaccine antigens by amplifying or modulating different signals involved in the innate immune response. The majority of known adjuvants have been empirically identified. The limited immunogenicity of new vaccine antigens and the need for safer vaccines have increased the importance of identifying single, well-defined adjuvants with known cellular and molecular mechanisms for rational vaccine design. Depletion or functional inhibition of CD4⁺CD25⁺FoxP3⁺ regulatory T cells (Tregs) by molecular adjuvants has become an emergent approach in this field. Different successful results have been obtained for specific vaccines, but there are still unresolved issues such as the risk of autoimmune disease induction, the involvement of cells other than Tregs and optimization for different conditions. This work provides a comprehensive analysis of current approaches to inhibit Tregs with molecular adjuvants for vaccine improvement, highlights the progress being made, and describes ongoing challenges.

Personalized neoantigen vaccines: A new approach to cancer immunotherapy

Neoantigens arise from somatic mutations that differ from wild-type antigens and are specific to each individual patient, which provide tumor specific targets for developing personalized cancer vaccines. Decades of work has increasingly shown the potential of targeting neoantigens to generate effective clinical responses. Current clinical trials using neoantigen targeting cancer vaccines, including in combination with checkpoint blockade monoclonal antibodies, have demonstrated potent T-cell responses against those neoantigens accompanied by antitumor effects in patients. Personalized neoantigen vaccines represent a potential new class of cancer immunotherapy.

The Role of Immune Checkpoint Inhibition in the Treatment of Brain Tumors

The standard of care for malignant gliomas of the brain has changed very little over the last few decades, and does not offer a cure for these rare, but fatal, tumors. The field of immunotherapy has brought potent new drugs into the oncological armamentarium, and is becoming recognized as a potentially important arm in the treatment of glioblastoma for adults. Immune checkpoints are inhibitory receptors found on immune cells that, when stimulated, cause those immune cells to become quiescent. While this is a natural mechanism to prevent excessive inflammatory damage and autoimmunity in otherwise healthy tissues, cancer cells may utilize this process to grow in the absence of targeted immune destruction. Antibodies derived to block the stimulation of these negative checkpoints, allowing immune cells to remain activated and undergo effector function, are a growing area of immunotherapy. These therapies have seen much success in both the preclinical and clinical arenas for various tumors, particularly melanoma and nonsmall-cell lung cancer. Multiple clinical trials are underway to determine if these drugs have efficacy in glioblastoma. Here, we review the current evidence, from early preclinical data to lessons learned from clinical trials outside of glioblastoma, to assess the potential of immune checkpoint inhibition in the treatment of brain tumors and discuss how this therapy may be implemented with the present standard of care.

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

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

Immune checkpoint inhibitor combinations in solid tumors: opportunities and challenges

The emergence of immune 'checkpoint inhibitors' such as cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed death receptor 1 (PD-1) has revolutionized treatment of solid tumors including melanoma, lung cancer, among many others. The goal of checkpoint inhibitor combination therapy is to improve clinical response and minimize toxicities. Rational design of checkpoint combinations considers immune-mediated mechanisms of antitumor activity: immunogenic cell death, antigen release and presentation, activation of T-cell responses, lymphocytic infiltration into tumors and depletion of immunosuppression. Potential synergistic combinations include checkpoint blockade with conventional (radiation, chemotherapy and targeted therapies) and newer immunotherapies (cancer vaccines, oncolytic viruses, among others). Reliable biomarkers are necessary to define patients who will achieve best clinical benefit with minimal toxicity in combination therapy.

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.

Noncoding RNAs and immune checkpoints-clinical implications as cancer therapeutics

A major mechanism of tumor development and progression is silencing of the patient's immune response to cancer-specific antigens. Defects in the so-called cancer immunity cycle may occur at any stage of tumor development. Within the tumor microenvironment, aberrant expression of immune checkpoint molecules with activating or inhibitory effects on T lymphocytes induces immune tolerance and cellular immune escape. Targeting immune checkpoint molecules such as programmed cell death protein 1 (PD-1) and its ligand PD-L1 with specific antibodies has proven to be a major advance in the treatment of several types of cancer. Another way to therapeutically influence the tumor microenvironment is by modulating the levels of microRNAs (miRNAs), small noncoding RNAs that shuttle bidirectionally between malignant and tumor microenvironmental cells. These small RNA transcripts have two features: (a) their expression is quite specific to distinct tumors, and (b) they are involved in early regulation of immune responses. Consequently, miRNAs may be ideal molecules for use in cancer therapy. Many miRNAs are aberrantly expressed in human cancer cells, opening new opportunities for cancer therapy, but the exact functions of these miRNAs and their interactions with immune checkpoint molecules have yet to be investigated. This review summarizes recently reported findings about miRNAs as modulators of immune checkpoint molecules and their potential application as cancer therapeutics in clinical practice.

The prognostic value of cytotoxic T-lymphocyte antigen 4 in cancers: a systematic review and meta-analysis

The outcomes of studies analyzing the prognostic role of CTLA-4 in cancers are controversial. Therefore, the aim of our meta-analysis was to clarify the correlation between CTLA-4 expression and OS in different cancer cases. Relevant literature was searched using PubMed, EMBASE, Web of Science, and the Cochrane Library. The clinicopathological features, hazard ratio (HR) and 95% confidence intervals (CI) were collected from these studies and were analyzed using Stata version 12.0 software. The pooled HR values showed no significant correlation between CTLA-4 expression levels and OS in relation to tumors (HR: 1.24, 95% CI: 0.98–1.56, I2 = 71.7%, P = 0.000). Further subgroup analyses were conducted and categorized by experimental methods, CTLA-4 sources and cancer types. The survey showed a significant correlation (HR: 1.47, 95% CI: 1.14–1.89) between high expression of CTLA-4 and OS in the SNP subgroup, and subgroups analyzing by PCR (HR: 1.50, 95% CI: 1.20–1.86) and flow cytometry (HR: 2.76, 95% CI: 1.49–5.14). In addition, our analysis observed significant differences between patients and controls in inCTLA-4+CD4+ lymphocytes, surCTLA-4+CD4+ lymphocytes, inCTLA-4+CD8+ lymphocytes, and surCTLA-4+CD8+ lymphocytes. Knowledge of the effects of CTLA-4 could potentially be used to effectively guide appropriate prognosis and therapeutic strategies in cancer patients.

Immune Checkpoint Inhibitors: Therapeutic Tools for Breast Cancer

Breast cancer is one of the major threats to female health, and its incidence is rapidly increasing in many countries. Currently, breast cancer is treated with surgery, followed by chemotherapy or radiation therapy, or both. However, a substantial proportion of breast cancer patients might have a risk for local relapse that leads to recurrence of their disease and/or metastatic breast cancer. Therefore searching for new and potential strategies for breast cancer treatment remains necessary. Immunotherapy is an attractive and promising approach that can exploit the ability of the immune system to identify and destroy tumors and thus prevent recurrence and metastatic lesions. The most promising and attractive approach of immunotherapeutic research in cancer is the blockade of immune checkpoints. In this review, we discuss the potential of certain inhibitors of immune checkpoints, such as antibodies targeting cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed death 1 (PD-1) and lymphocyte activation gene-3 (LAG-3), in breast cancer therapeutics. Immune checkpoint inhibitors may represent future standards of care for breast cancer as monotherapy or combined with standard therapies.

A New VISTA on combination therapy for negative checkpoint regulator blockade

Negative checkpoint regulators function to restrain T cell responses to maintain tolerance and limit immunopathology. However, in the setting of malignancy, these pathways work in concert to promote immune-mediate escape leading to the development of a clinically overt cancer. In the recent years, clinical trials demonstrating the efficacy of blocking antibodies against these molecules have invigorated the field of immunotherapy. In this review, we discuss the current understanding on established NCR blockade and how strategic combination therapy with anti-VISTA antibody can be used to target multiple non-redundant NCR pathways.

Checkpoint Proteins in Pediatric Brain and Extracranial Solid Tumors: Opportunities for Immunotherapy

Pediatric brain and extracranial solid tumors are a diverse group of malignancies that represent almost half of all pediatric cancers. Standard therapy includes various combinations of surgery, cytotoxic chemotherapy, and radiation, which can be very harmful to a developing child, and survivors carry a substantial burden of long-term morbidities. Although these therapies have improved survival rates for children with solid tumors, outcomes still remain extremely poor for subsets of patients. Recently, immunosuppressive checkpoint molecules that negatively regulate immune cell function have been described. When found on malignant cells or in the tumor microenvironment, they contribute to immune evasion and tumor escape. Agents designed to inhibit these proteins have demonstrated significant efficacy in human adult solid tumor studies. However, there is limited research focusing on immune checkpoint molecules and inhibitors in pediatric solid tumors. In this review, we examine the current knowledge on immune checkpoint proteins with an emphasis on cytotoxic T lymphocyte antigen-4 (CTLA-4); programmed cell death protein-1 (PD-1) and programmed death-ligand 1 (PD-L1); OX-2 membrane glycoprotein (CD200); and indoleamine 2,3-dioxygenase (IDO). We review T-cell signaling, the mechanisms of action of these checkpoint molecules, pediatric preclinical studies on checkpoint proteins and checkpoint blockade, pediatric checkpoint inhibitor clinical trials conducted to date, and future immunotherapy opportunities for childhood cancers. Clin Cancer Res; 23(2); 342-50. ©2016 AACR.

Is There Still Room for Cancer Vaccines at the Era of Checkpoint Inhibitors

Checkpoint inhibitor (CPI) blockade is considered to be a revolution in cancer therapy, although most patients (70%–80%) remain resistant to this therapy. It has been hypothesized that only tumors with high mutation rates generate a natural antitumor T cell response, which could be revigorated by this therapy. In patients with no pre-existing antitumor T cells, a vaccine-induced T cell response is a rational option to counteract clinical resistance. This hypothesis has been validated in preclinical models using various cancer vaccines combined with inhibitory pathway blockade (PD-1-PDL1-2, CTLA-4-CD80-CD86). Enhanced T cell infiltration of various tumors has been demonstrated following this combination therapy. The timing of this combination appears to be critical to the success of this therapy and multiple combinations of immunomodulating antibodies (CPI antagonists or costimulatory pathway agonists) have reinforced the synergy with cancer vaccines. Only limited results are available in humans and this combined approach has yet to be validated. Comprehensive monitoring of the regulation of CPI and costimulatory molecules after administration of immunomodulatory antibodies (anti-PD1/PD-L1, anti-CTLA-4, anti-OX40, etc.) and cancer vaccines should help to guide the selection of the best combination and timing of this therapy.

Treg subsets in inflammatory bowel disease and colorectal carcinoma: Characteristics, role, and therapeutic targets

T regulatory cells (Tregs) play an important role in the regulation of autoimmunity, autoinflammation, allergic diseases, infection, and the tumor environment. Different subsets are characterized that use a number of regulatory mechanisms. Tregs can influence the progression of inflammatory bowel disease and the development of colorectal cancer. Knowledge of Tregs and their regulatory mechanisms can provide new targets for therapeutic intervention.