Potentiating endogenous antitumor immunity to prostate cancer through combination immunotherapy with CTLA4 blockade and GM-CSF

Immunotherapy in Prostate Cancer: State of Art and New Therapeutic Perspectives

Prostate cancer (PC) is the most common type of tumor in men. In the early stage of the disease, it is sensitive to androgen deprivation therapy. In patients with metastatic castration-sensitive prostate cancer (mHSPC), chemotherapy and second-generation androgen receptor therapy have led to increased survival. However, despite advances in the management of mHSPC, castration resistance is unavoidable and many patients develop metastatic castration-resistant disease (mCRPC). In the past few decades, immunotherapy has dramatically changed the oncology landscape and has increased the survival rate of many types of cancer. However, immunotherapy in prostate cancer has not yet given the revolutionary results it has in other types of tumors. Research into new treatments is very important for patients with mCRPC because of its poor prognosis. In this review, we focus on the reasons for the apparent intrinsic resistance of prostate cancer to immunotherapy, the possibilities for overcoming this resistance, and the clinical evidence and new therapeutic perspectives regarding immunotherapy in prostate cancer with a look toward the future.

Recombinant GM-CSF for diseases of GM-CSF insufficiency: Correcting dysfunctional mononuclear phagocyte disorders

Introduction

Endogenous granulocyte-macrophage colony-stimulating factor (GM-CSF), identified by its ability to support differentiation of hematopoietic cells into several types of myeloid cells, is now known to support maturation and maintain the metabolic capacity of mononuclear phagocytes including monocytes, macrophages, and dendritic cells. These cells sense and attack potential pathogens, present antigens to adaptive immune cells, and recruit other immune cells. Recombinant human (rhu) GM-CSF (e.g., sargramostim [glycosylated, yeast-derived rhu GM-CSF]) has immune modulating properties and can restore the normal function of mononuclear phagocytes rendered dysfunctional by deficient or insufficient endogenous GM-CSF.

Methods

We reviewed the emerging biologic and cellular effects of GM-CSF. Experts in clinical disease areas caused by deficient or insufficient endogenous GM-CSF examined the role of GM-CSF in mononuclear phagocyte disorders including autoimmune pulmonary alveolar proteinosis (aPAP), diverse infections (including COVID-19), wound healing, and anti-cancer immune checkpoint inhibitor therapy.

Results

We discuss emerging data for GM-CSF biology including the positive effects on mitochondrial function and cell metabolism, augmentation of phagocytosis and efferocytosis, and immune cell modulation. We further address how giving exogenous rhu GM-CSF may control or treat mononuclear phagocyte dysfunction disorders caused or exacerbated by GM-CSF deficiency or insufficiency. We discuss how rhu GM-CSF may augment the anti-cancer effects of immune checkpoint inhibitor immunotherapy as well as ameliorate immune-related adverse events.

Discussion

We identify research gaps, opportunities, and the concept that rhu GM-CSF, by supporting and restoring the metabolic capacity and function of mononuclear phagocytes, can have significant therapeutic effects. rhu GM-CSF (e.g., sargramostim) might ameliorate multiple diseases of GM-CSF deficiency or insufficiency and address a high unmet medical need.

Combinatorial approaches of nanotherapeutics for inflammatory pathway targeted therapy of prostate cancer

Prostate cancer (PC) is the most prevalent male urogenital cancer worldwide. PC patients presenting an advanced or metastatic cancer succumb to the disease, even after therapeutic interventions including radiotherapy, surgery, androgen deprivation therapy (ADT), and chemotherapy. One of the hallmarks of PC is evading immune surveillance and chronic inflammation, which is a major challenge towards designing effective therapeutic formulations against PC. Chronic inflammation in PC is often characterized by tumor microenvironment alterations, epithelial-mesenchymal transition and extracellular matrix modifications. The inflammatory events are modulated by reactive nitrogen and oxygen species, inflammatory cytokines and chemokines. Major signaling pathways in PC includes androgen receptor, PI3K and NF-κB pathways and targeting these inter-linked pathways poses a major therapeutic challenge. Notably, many conventional treatments are clinically unsuccessful, due to lack of targetability and poor bioavailability of the therapeutics, untoward toxicity and multidrug resistance. The past decade witnessed an advancement of nanotechnology as an excellent therapeutic paradigm for PC therapy. Modern nanovectorization strategies such as stimuli-responsive and active PC targeting carriers offer controlled release patterns and superior anti-cancer effects. The current review initially describes the classification, inflammatory triggers and major inflammatory pathways of PC, various PC treatment strategies and their limitations. Subsequently, recent advancement in combinatorial nanotherapeutic approaches, which target PC inflammatory pathways, and the mechanism of action are discussed. Besides, the current clinical status and prospects of PC homing nanovectorization, and major challenges to be addressed towards the advancement PC therapy are also addressed.

GM-CSF: A Double-Edged Sword in Cancer Immunotherapy

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine that drives the generation of myeloid cell subsets including neutrophils, monocytes, macrophages, and dendritic cells in response to stress, infections, and cancers. By modulating the functions of innate immune cells that serve as a bridge to activate adaptive immune responses, GM-CSF globally impacts host immune surveillance under pathologic conditions. As with other soluble mediators of immunity, too much or too little GM-CSF has been found to promote cancer aggressiveness. While too little GM-CSF prevents the appropriate production of innate immune cells and subsequent activation of adaptive anti-cancer immune responses, too much of GM-CSF can exhaust immune cells and promote cancer growth. The consequences of GM-CSF signaling in cancer progression are a function of the levels of GM-CSF, the cancer type, and the tumor microenvironment. In this review, we first discuss the secretion of GM-CSF, signaling downstream of the GM-CSF receptor, and GM-CSF’s role in modulating myeloid cell homeostasis. We then outline GM-CSF’s anti-tumorigenic and pro-tumorigenic effects both on the malignant cells and on the non-malignant immune and other cells in the tumor microenvironment. We provide examples of current clinical and preclinical strategies that harness GM-CSF’s anti-cancer potential while minimizing its deleterious effects. We describe the challenges in achieving the Goldilocks effect during administration of GM-CSF-based therapies to patients with cancer. Finally, we provide insights into how technologies that map the immune microenvironment spatially and temporally may be leveraged to intelligently harness GM-CSF for treatment of malignancies.

Reforming the Chimeric Antigen Receptor by Peptide Towards Optimized CAR T Cells With Enhanced Anti-Cancer Potency and Safety

The emerging chimeric antigen receptor (CAR) T cell revolutionized the clinic treatment of hematological cancers, but meet its Waterloo in solid tumor therapy. Although there exist many reasons for this limitation, one of the largest challenges is the scarcity of recognition for tumor cells, resulting in the undesirable side effects and the subsequent ineffectiveness. To overcome it, a lung-cancer-cell-targeting peptide termed A1 was used in this work to reform the scFv domain of CAR by genetic manipulation. As a result, this modified ^A1CAR T exhibited the optimized cancer-cell targeting and cytotoxicity in vitro and in vivo. More importantly, by tuning the sensitivity of CAR to antigen, peptide-based ^A1CAR T cells could distinguish tumors from normal tissue, thereby eliminating the off-tumor toxicity in healthy organs. Collectively, we herein constructed a genetic peptide-engineered CAR T cells by inserting A1 peptide into the scFv domain. Profitted from the optimized recognition pattern and sensitivity, ^A1CAR T cells showed the ascendancy in solid tumor treatment. Our findings demonstrate that peptide-based CAR T holds great potential in solid tumor therapy due to an excellent targeting ability towards tumor cells.

Fresh tissue procurement and preparation for multicompartment and multimodal analysis of the prostate tumor microenvironment

BACKGROUND

Prostatic cancers include a diverse microenvironment of tumor cells, cancer-associated fibroblasts, and immune components. This tumor microenvironment (TME) is a known driving force of tumor survival after treatment, but the standard-of-care tissue freezing or fixation in pathology practice limit the use of available approaches/tools to study the TME's functionality in tumor resistance. Thus, there is a need for approaches that satisfy both clinical and laboratory endpoints for TME study. Here we present methods for clinical case identification, tissue processing, and analytical workflow that are compatible with standard histopathology while enabling molecular and functional interrogation of prostate TME components.

METHODS

We first performed a small retrospective review to identify cases where submission of alternate prostate tissue slices and a parallel live tissue processing protocol complement traditional histopathology and enable viable multicompartment analysis of the TME. Then, we tested its compatibility with commonly employed methods to study the microenvironment including quantification of components both in situ and after tissue dissociation. We also evaluated tissue digestion conditions and cell isolation techniques to aid various molecular and functional endpoints.

RESULTS

We identified Gleason Grade Group 3+ clinical cases where tumor volume was sufficient to allow slicing of unfixed tissue and distribution of alternating tissue slices to standard-of-care histopathology and viable multi-modal TME analyses. No single method was found that preserved cellular sub-types for all downstream readouts; instead, tissues were further divided so techniques could be catered to each endpoint. For instance, we show that incorporating the protease dispase into tissue dissociation improves viability for culture and functional analyses but hinders immune cell analysis by flow cytometry. We also found that flow activated cell sorting provides highly pure cell populations for quantitative reverse-transcription polymerase chain reaction and RNA-seq while isolation using antibody-labeled paramagnetic particles facilitated functional coculture experiments.

CONCLUSIONS

The identification of candidate cases and use of these techniques enable translational research and the development of molecular and functional assays to facilitate prostate TME study without compromising standard-of-care histopathological diagnosis. This allows bridging clinical histopathology and further interrogation of the prostate TME and promises to advance our understanding of tumor biology and unveil new predictive and prognostic markers of prostate cancer progression.

Monoclonal Antibodies to CTLA-4 with Focus on Ipilimumab

The immune checkpoint cytotoxic T lymphocyte-associated antigen 4 (CTLA-4 or CD152) is a negative regulator of T-cell-mediated immune responses which plays a critical role in suppressing autoimmunity and maintaining immune homeostasis. Because of its inhibitory activity on T cells, CTLA-4 has been investigated as a drug target to induce immunostimulation, blocking the interaction with its ligands. The antitumor effects mediated by CTLA-4 blockade have been attributed to a sustained active immune response against cancer cells, due to the release of a brake on T cell activation. Ipilimumab (Yervoy, Bristol-Myers Squibb) is a fully human anti-CTLA-4 IgG1κ monoclonal antibody (mAb) that represents the first immune checkpoint inhibitor approved as monotherapy by FDA and EMA in 2011 for the treatment of unresectable/metastatic melanoma. In 2015, FDA also granted approval to ipilimumab monotherapy as adjuvant treatment of stage III melanoma to reduce the risk of tumour recurrence. The subsequent approved indications of ipilimumab for metastatic melanoma, regardless of BRAF mutational status, and other advanced/metastatic solid tumours always involve its use in association with the anti-programmed cell death protein 1 (PD-1) mAb nivolumab. Currently, ipilimumab is evaluated in ongoing clinical trials for refractory/advanced solid tumours mainly in combination with additional immunostimulating agents.

Clinical experience with CTLA-4 blockade for cancer immunotherapy: From the monospecific monoclonal antibody ipilimumab to probodies and bispecific molecules targeting the tumor microenvironment

The immune checkpoint cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is an inhibitory regulator of T-cell mediated responses that has been investigated as target of monoclonal antibodies (mAbs) for cancer immunotherapy. The anti-CTLA-4 mAb ipilimumab represents the first immune checkpoint inhibitor that significantly improved overall survival in patients with unresectable/metastatic melanoma. The subsequent approved indications (often in the first-line setting) for melanoma and other advanced/metastatic solid tumors always require ipilimumab combination with nivolumab, an anti-programmed cell death protein 1 (PD-1) mAb. However, the improved clinical efficacy of the mAb combination is associated with increased immune-related adverse events, which might require treatment discontinuation even in responding patients. This drawback is expected to be overcome by the recent development of anti-CTLA-4 probodies proteolitycally activated in the tumor microenvironment and bispecific molecules targeting both CTLA-4 and PD-1, whose co-expression is characteristic of tumor-infiltrating T cells. These molecules would preferentially stimulate immune responses against the tumor, reducing toxicity toward normal tissues.

Current Treatment Modalities Targeting Tumor Microenvironment in Castration-Resistant Prostate Cancer

Prostate cancer (PCa) is responsible for significant cancer-related morbidity and mortality following local treatment failure in men. The initial stages of PCa are typically managed with a combination of surgical resection and/or androgen deprivation therapy (ADT). Unfortunately, a significant proportion of PCa continues to progress despite being at castrate levels of testosterone (<50 ng/dl), at which point it is coined castration-resistant prostate cancer (CRPC). In recent years, many novel therapeutics and drug combinations have been created for CRPC patients. These include immune checkpoint inhibitors, chemokine receptor antagonists, steroidogenic enzyme inhibition, and novel tyrosine kinase inhibitors as well as combinations of drugs. The selection of the most appropriate therapy depends on several factors like stage of the disease, age of the patient, metastasis, functional status, and response towards previous therapies. Here, we review the current state of the literature regarding treatment modalities, focusing on the treatment recommendations per the American Urological Association (AUA), recent clinical trials, and their limitations. An accurate and reliable overview of the strengths and limitations of PCa therapeutics could also allow personalized therapeutic interventions against PCa.

How to turn up the heat on the cold immune microenvironment of metastatic prostate cancer

BACKGROUND

Advanced prostate cancer remains one of the most common and deadly cancers, despite advances in treatment options. Immunotherapy has provided little benefit to a majority of patients, largely due to the immunosuppressive tumor microenvironment that gives rise to inherently "cold tumors". In this review, we discuss the immunopathology of the prostate tumor microenvironment, strategies for treating prostate cancer with immunotherapies, and a perspective on potential approaches to enhancing the efficacy of immunotherapies.

METHODS

Databases, including PubMed, Google Scholar, and Cochrane, were searched for articles relevant to the immunology of prostate cancer. We discuss the impact of different types of treatments on the immune system, and potential mechanisms through which prostate cancer evades the immune system.

RESULTS

The tumor microenvironment associated with prostate cancer is highly immunosuppressive due to (1) the function of regulatory T cells, tumor-associated macrophages, and myeloid-derived suppressor cells (MDSCs), (2) the cytokine milieu secreted by tumor stromal cells and fibroblasts, and (3) the production of adenosine via prostatic acid phosphatase. Both adenosine and tumor growth factor beta (TGF-beta) serve as potent immunosuppressive molecules that could also represent potential therapeutic targets. While there have been many immunotherapy trials in prostate cancer, the majority of these trials have targeted a single immunosuppressive mechanism resulting in limited clinical efficacy. Future approaches will require the integration of improved patient selection as well as use of combination therapies to address multiple mechanisms of resistance.

CONCLUSION

Prostate cancer inherently gives rise to multiple immunosuppressive mechanisms that have been difficult to overcome with any one immunotherapeutic approach. Enhancing the clinical activity of immunotherapies will require strategic combinations of multiple therapies to address the emerging mechanisms of tumor immune resistance.

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.

Combination immunotherapy induces distinct T-cell repertoire responses when administered to patients with different malignancies

Background

CTLA-4 blockade with ipilimumab is Food and Drug Administration-approved for melanoma as a monotherapy and has been shown to modulate the circulating T-cell repertoire. We have previously reported clinical trials combining CTLA-4 blockade with granulocyte-macrophage colony-stimulating factor (GM-CSF) in metastatic melanoma patients and in metastatic castration resistant prostate cancer (mCRPC) patients. Here, we investigate the effect that cancer type has on circulating T cells in metastatic melanoma and mCRPC patients, treated with ipilimumab and GM-CSF.

Methods

We used next-generation sequencing of T-cell receptors (TCR) to compare the circulating T cells of melanoma and mCRPC patients receiving the same treatment with ipilimumab and GM-CSF by Wilcoxon rank sum test. Flow cytometry was utilized to investigate specific T-cell populations. TCR sequencing results were correlated with each T-cell subpopulation by Spearman’s rank correlation coefficient. Of note, 14 metastatic melanoma patients had samples available for TCR sequencing and 21 had samples available for flow cytometry analysis; 37 mCRPC patients had samples available for sequencing of whom 22 have TCR data available at both timepoints; 20 of these patients had samples available for flow cytometry analysis and 16 had data available at both timepoints.

Results

While melanoma and mCRPC patients had similar pretreatment circulating T-cell counts, treatment induces greater expansion of circulating T cells in melanoma patients. Metastatic melanoma patients have a higher proportion of clones that increased more than fourfold after the treatment compared with mCRPC patients (18.9% vs 11.0%, p=0.017). Additionally, melanoma patients compared with mCRPC patients had a higher ratio of convergent frequency (1.22 vs 0.60, p=0.012). Decreases in clonality induced by treatment are associated with baseline CD8+ T-cell counts in both patient groups, but are more pronounced in the melanoma patients (r=−0.81, p<0.001 vs r=−0.59, p=0.02).

Trial registration numbers

NCT00064129; NCT01363206.

Immune Checkpoint Inhibitors in Prostate Cancer

Simple Summary

Metastatic prostate cancer is an incurable disease with limited treatment options. Immunotherapy has demonstrated significant success in multiple cancer types but efforts to harness its benefit in prostate cancer have so far largely been unsuccessful. In this review, we analyze the preclinical rationale for the use of immunotherapy and underlying barriers preventing responses to it. We summarize clinical studies evaluating checkpoint inhibitors in prostate cancer. In the end, we review ongoing trials exploring combination immune checkpoint inhibitors in combination with other agents with the intent to modulate the immune system to improve treatment outcomes.

Abstract

Metastatic prostate cancer is a lethal disease with limited treatment options. Immune checkpoint inhibitors have dramatically changed the treatment landscape of multiple cancer types but have met with limited success in prostate cancer. In this review, we discuss the preclinical studies providing the rationale for the use of immunotherapy in prostate cancer and underlying biological barriers inhibiting their activity. We discuss the predictors of response to immunotherapy in prostate cancer. We summarize studies evaluating immune checkpoint inhibitors either as a single agent or in combination with other checkpoint inhibitors or with other agents such as inhibitors of androgen axis, poly ADP-ribose polymerase (PARP), radium-223, radiotherapy, cryotherapy, tumor vaccines, chemotherapy, tyrosine kinase inhibitors, and granulocyte-macrophage colony-stimulating factor. We thereafter review future directions including the combination of immune checkpoint blockade with inhibitors of adenosine axis, bispecific T cell engagers, PSMA directed therapies, adoptive T-cell therapy, and multiple other miscellaneous agents.

Cancer/testis antigens: from serology to mRNA cancer vaccine

Cancer/testis antigens (CTAs) are a group of tumor antigens expressed in numerous cancer tissues, as well as in the testis and placental tissues. There are over 200 CTAs supported by serology and expression data. The expression patterns of CTAs reflect the similarities between the processes of gametogenesis and tumorigenesis. It is notable that CTAs are highly expressed in three types of cancers (lung cancer, bladder cancer, and skin cancer), all of which have a metal etiology. Here, we review the expression, regulation, and function of CTAs and their translational prospects as cancer biomarkers and treatment targets. Many CTAs are highly immunogenic, tissue-specific, and frequently expressed in cancer tissues but not under physiological conditions, rendering them promising candidates for cancer detection. Some CTAs are associated with clinical outcomes, so they may serve as prognostic biomarkers. A small number of CTAs are membrane-bound, making them ideal targets for chimeric antigen receptor (CAR) T cells. Mounting evidence suggests that CTAs induce humoral or cellular immune responses, providing cancer immunotherapeutic opportunities for T-cell receptors (TCRs), CAR T cell, antibody-based therapy and peptide- or mRNA-based vaccines. Indeed, CTAs are the dominating non-mutated targets in mRNA cancer vaccine development. Clinical trials on CTA TCR and vaccines have shown effectiveness, safety, and tolerance, but these successes are limited to a small number of patients. In-depth studies on CTA expression and function are needed to improve CTA-based immunotherapy.

Immune Checkpoints, Inhibitors and Radionuclides in Prostate Cancer: Promising Combinatorial Therapy Approach

Emerging research demonstrates that co-inhibitory immune checkpoints (ICs) remain the most promising immunotherapy targets in various malignancies. Nonetheless, ICIs have offered insignificant clinical benefits in the treatment of advanced prostate cancer (PCa) especially when they are used as monotherapies. Current existing PCa treatment initially offers an improved clinical outcome and overall survival (OS), however, after a while the treatment becomes resistant leading to aggressive and uncontrolled disease associated with increased mortality and morbidity. Concurrent combination of the ICIs with radionuclides therapy that has rapidly emerged as safe and effective targeted approach for treating PCa patients may shift the paradigm of PCa treatment. Here, we provide an overview of the contextual contribution of old and new emerging inhibitory ICs in PCa, preclinical and clinical studies supporting the use of these ICs in treating PCa patients. Furthermore, we will also describe the potential of using a combinatory approach of ICIs and radionuclides therapy in treating PCa patients to enhance efficacy, durable cancer control and OS. The inhibitory ICs considered in this review are cytotoxic T-lymphocyte antigen 4 (CTLA4), programmed cell death 1 (PD1), V-domain immunoglobulin suppressor of T cell activation (VISTA), indoleamine 2,3-dioxygenase (IDO), T cell Immunoglobulin Domain and Mucin Domain 3 (TIM-3), lymphocyte-activation gene 3 (LAG-3), T cell immunoreceptor with Ig and ITIM domains (TIGIT), B7 homolog 3 (B7-H3) and B7-H4.

Non-radioactive and sensitive tracking of neutrophils towards inflammation using antibody functionalized magnetic particle imaging tracers

White blood cells (WBCs) are a key component of the mammalian immune system and play an essential role in surveillance, defense, and adaptation against foreign pathogens. Apart from their roles in the active combat of infection and the development of adaptive immunity, immune cells are also involved in tumor development and metastasis. Antibody-based therapeutics have been developed to regulate (i.e. selectively activate or inhibit immune function) and harness immune cells to fight malignancy. Alternatively, non-invasive tracking of WBC distribution can diagnose inflammation, infection, fevers of unknown origin (FUOs), and cancer. Magnetic Particle Imaging (MPI) is a non-invasive, non-radioactive, and sensitive medical imaging technique that uses safe superparamagnetic iron oxide nanoparticles (SPIOs) as tracers. MPI has previously been shown to track therapeutic stem cells for over 87 days with a ~200 cell detection limit. In the current work, we utilized antibody-conjugated SPIOs specific to neutrophils for in situ labeling, and non-invasive and radiation-free tracking of these inflammatory cells to sites of infection and inflammation in an in vivo murine model of lipopolysaccharide-induced myositis. MPI showed sensitive detection of inflammation with a contrast-to-noise ratio of ~8-13.

CTLA-4 blockade synergizes with cryoablation to mediate tumor rejection

We report that cryoablation of primary tumors synergizes with anti-CTLA-4 treatment to mediate rejection of secondary tumors in the TRAMP mouse model of prostate cancer. T cells, in particular CD8⁺ T cells specific for the TRAMP antigen SPAS-1, were enriched in both secondary tumors and spleens of combination-treated mice.

Gonadotropin-Releasing Hormone Receptors in Prostate Cancer: Molecular Aspects and Biological Functions

Pituitary Gonadotropin-Releasing Hormone receptors (GnRH-R) mediate the activity of the hypothalamic decapeptide GnRH, thus playing a key role in the regulation of the reproductive axis. Early-stage prostate cancer (PCa) is dependent on serum androgen levels, and androgen-deprivation therapy (ADT), based on GnRH agonists and antagonists, represents the standard therapeutic approach for PCa patients. Unfortunately, the tumor often progresses towards the more aggressive castration-resistant prostate cancer (CRPC) stage. GnRH receptors are also expressed in CRPC tissues, where their binding to both GnRH agonists and antagonists is associated with significant antiproliferative/proapoptotic, antimetastatic and antiangiogenic effects, mediated by the Gαi/cAMP signaling cascade. GnRH agonists and antagonists are now considered as an effective therapeutic strategy for CRPC patients with many clinical trials demonstrating that the combined use of these drugs with standard therapies (i.e., docetaxel, enzalutamide, abiraterone) significantly improves disease-free survival. In this context, GnRH-based bioconjugates (cytotoxic drugs covalently linked to a GnRH-based decapeptide) have been recently developed. The rationale of this treatment is that the GnRH peptide selectively binds to its receptors, delivering the cytotoxic drug to CRPC cells while sparing nontumor cells. Some of these compounds have already entered clinical trials.

Clinical application of immune checkpoints in targeted immunotherapy of prostate cancer

Immunotherapy is considered as an effective method for cancer treatment owing to the induction of specific and long-lasting anti-cancer effects. Immunotherapeutic strategies have shown significant success in human malignancies, particularly in prostate cancer (PCa), a major global health issue regarding its high metastatic rates. In fact, the first cancer vaccine approved by FDA was Provenge, which has been successfully used for treatment of PCa. Despite the remarkable success of cancer immunotherapy in PCa, many of the developed immunotherapy methods show poor therapeutic outcomes. Immunosuppression in tumor microenvironment (TME) induced by non-functional T cells (CD4+ and CD8+), tolerogenic dendritic cells (DCs), and regulatory T cells, has been reported to be the main obstacle to the effectiveness of anti-tumor immune responses induced by an immunotherapy method. The present review particularly focuses on the latest findings of the immune checkpoints (ICPs), including CTLA-4, PD-1, PD-L1, LAG-3, OX40, B7-H3, 4-1BB, VISTA, TIM-3, and ICOS; these checkpoints are able to have immune modulatory effects on the TME of PCa. This paper further discusses different approaches in ICPs targeting therapy and summarizes the latest advances in the clinical application of ICP-targeted therapy as monotherapy or in combination with other cancer therapy modalities in PCa.

Antibody and antibody fragments for cancer immunotherapy

Antibody has become the most rapidly expanding class of pharmaceuticals for treating a wide variety of human diseases including cancers. Especially, with the fast development of cancer immunotherapy, antibody drugs have become the most promising therapeutic for curing cancers. Immune-mediated cell killing by antibodies including antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cell phagocytosis (ADCP) and complement-dependent cytotoxicity (CDC) as well as regulation of T cell function through immune checkpoint blockade. Due to the absence of Fc fragment, antibody fragments including single-chain variable fragments (scFvs) and single-domain antibodies (sdAds) are mainly applied in chimeric antigen receptors (CAR) T cell therapy for redirecting T cells to tumors and T cell activation by immune checkpoint blockade. In this review, the cancer immunity is first discussed. Then the principal mechanisms of antibody-based immunotherapy will be reviewed. Next, the antibody and antibody fragments applied for cancer immunotherapy will be summarized. Bispecific and multispecific antibodies and a combination of cancer immunotherapy with other tumor treatments will also be mentioned. Finally, an outlook and perspective of antibody-based cancer immunotherapy will be given. This review would provide a comprehensive guidance for the researchers who are interested in and intended to involve in the antibodies- or antibody fragments-based tumor immunity.

Manipulation of the Immune System for Cancer Defeat: A Focus on the T Cell Inhibitory Checkpoint Molecules

The immune system actively counteracts the tumorigenesis process; a breakout of the immune system function, or its ability to recognize transformed cells, can favor cancer development. Cancer becomes able to escape from immune system control by using multiple mechanisms, which are only in part known at a cellular and molecular level. Among these mechanisms, in the last decade, the role played by the so-called "inhibitory immune checkpoints" is emerging as pivotal in preventing the tumor attack by the immune system. Physiologically, the inhibitory immune checkpoints work to maintain the self-tolerance and attenuate the tissue injury caused by pathogenic infections. Cancer cell exploits such immune-inhibitory molecules to contrast the immune intervention and induce tumor tolerance. Molecular agents that target these checkpoints represent the new frontier for cancer treatment. Despite the heterogeneity and multiplicity of molecular alterations among the tumors, the immune checkpoint targeted therapy has been shown to be helpful in selected and even histologically different types of cancer, and are currently being adopted against an increasing variety of tumors. The most frequently used is the moAb-based immunotherapy that targets the Programmed Cell Death 1 protein (PD-1), the PD-1 Ligand (PD-L1) or the cytotoxic T lymphocyte antigen-4 (CTLA4). However, new therapeutic approaches are currently in development, along with the discovery of new immune checkpoints exploited by the cancer cell. This article aims to review the inhibitory checkpoints, which are known up to now, along with the mechanisms of cancer immunoediting. An outline of the immune checkpoint targeting approaches, also including combined immunotherapies and the existing trials, is also provided. Notwithstanding the great efforts devoted by researchers in the field of biomarkers of response, to date, no validated FDA-approved immunological biomarkers exist for cancer patients. We highlight relevant studies on predictive biomarkers and attempt to discuss the challenges in this field, due to the complex and largely unknown dynamic mechanisms that drive the tumor immune tolerance.

Morphological spectrum of immune check-point inhibitor therapy-associated gastritis

AIMS

Immune check-point inhibitors are frequently used in the treatment of a variety of solid tumours. The mechanism of action of these drugs involves up-regulation of cytotoxic T cells, which can lead to a lack of self-tolerance and immune-related adverse events, including those involving the gastrointestinal tract. This study was performed to characterise the histological features of immune check-point inhibitor therapy-associated gastritis.

METHODS AND RESULTS

Gastric biopsies from patients on immune check-point inhibitor therapy with clinical suspicion of drug-associated gastrointestinal injury were identified. The predominant histological pattern of injury, distribution of injury, degree of tissue eosinophilia and prominence of apoptosis were recorded. Presenting symptoms, treatment and follow-up data were obtained by medical chart review. The 12 patients included in the study group were treated with ipilimumab, nivolumab or pembrolizumab for a variety of tumours. Symptoms at presentation included nausea, vomiting and diarrhoea. Chronic active gastritis with intra-epithelial lymphocytosis and prominent apoptosis was seen in eight of 12 patients, and was the most useful combination for the diagnosis of drug-induced gastritis in these patients. Four patients showed focal enhancing gastritis with a lymphohistiocytic cuff around inflamed glands reminiscent of Crohn's disease. One of those four patients was homozygous for the ATG16L1 Crohn's disease-associated gene variant, but had no history of inflammatory bowel disease. Ten patients responded to medication withdrawal and steroid therapy, while two required treatment with infliximab.

CONCLUSIONS

Awareness of the morphological spectrum of immune check-point inhibitor therapy-associated gastritis is important for the accurate diagnosis and prompt management of these patients.

Immune checkpoint inhibitor-associated pituitary-adrenal dysfunction: A systematic review and meta-analysis

With the growing use of immune checkpoint inhibitors (ICIs), case reports of rare yet life-threatening pituitary-adrenal dysfunctions, particularly for hypopituitarism, are increasingly being published. In this analysis, we focus on these events by including the most recent publications and reports from early phase I/II and phase III clinical trials and comparing the incidence and risks across different ICI regimens. PubMed, Embase, and the Cochrane Library were systematically searched from inception to April 2019 for clinical trials that reported on pituitary-adrenal dysfunction. The rates of events, odds ratios (ORs), and 95% confidence intervals (CIs) were obtained using random effects meta-analysis. The analyses included data from 160 trials involving 40 432 participants. The rate was 2.43% (95% CI, 1.73%-3.22%) for all-grade adrenal insufficiency and 3.25% (95% CI, 2.15%-4.51%) for hypophysitis. Compared with the placebo or other therapeutic regimens, ICI agents were associated with a higher incidence of serious-grade adrenal insufficiency (OR 3.19, 95% CI, 1.84 to 5.54) and hypophysitis (OR 4.77, 95% CI, 2.60 to 8.78). Among 71 serious-grade hypopituitarism instances in 12 336 patients, there was a significant association between ICIs and hypopituitarism (OR 3.62, 95% CI, 1.86 to 7.03). Substantial heterogeneity was noted across the studies for the rates of these events, which in part was attributable to the different types of ICIs and varied phases of the clinical trials. Although the rates of these events were low, the risk was increased following ICI-based treatment, particularly for CTLA-4 inhibitors, which were associated with a higher incidence of pituitary-adrenal dysfunction than PD-1/PD-L1 inhibitors.

Icaritin promotes tumor T-cell infiltration and induces antitumor immunity in mice

Icaritin, a hydrolytic product of icariin isolated from traditional Chinese herbal medicine genus Epimedium, has many pharmacological and biological activities. Here, we show that icaritin can effectively decrease tumor burden of murine B16F10 melanoma and MC38 colorectal tumors in a T-cell dependent manner. The treatment effects are associated with increased CD8 T-cell infiltration and increased effector memory T-cell frequency. In vivo depletion of CD8 T cell using an anti-CD8 monoclonal antibody abolished the antitumor effect, which supports the critical role of CD8 T cells during icaritin treatment. By analyzing immune cells in the tumor tissue, we found reduced frequency of CD11b⁺ Gr1⁺ myeloid-derived suppression cells (MDSCs) infiltration and downregulation of PD-L1 expression on MDSCs after icaritin treatment. This was not limited to MDSCs, as icaritin also decreased the expression of PD-L1 on neutrophils. Importantly, the combination of anti-PD-1/CTLA-4 and icaritin significantly enhances antitumor ability and increases the efficacy of either treatment alone. Our findings reveal that icaritin induces antitumor immunity in a CD8 T-cell-dependent way and justify further investigation of combining immune checkpoint therapy to icaritin-based antitumor therapy.

Immune-based therapies for metastatic prostate cancer: an update

Prostate cancer (PC) is a common malignancy among elderly males and is noncurable once it becomes metastatic. In recent years, a number of antigen-delivery systems have emerged as viable and promising immunotherapeutic agents against PC. The approval of sipuleucel-T by the US FDA for the treatment of males with asymptomatic or minimally symptomatic castrate resistant PC was a landmark in cancer immunotherapy, making this the first approved immunotherapeutic. A number of vaccines are under clinical investigation, each having its own set of advantages and disadvantages. Here, we discuss the basic technologies underlying these different delivery modes, we discuss the completed and current human clinical trials, as well as the use of vaccines in combination with immune checkpoint inhibitors.

Nanobody-based CAR T cells that target the tumor microenvironment inhibit the growth of solid tumors in immunocompetent mice

Chimeric antigen receptor (CAR) T cell therapy has been successful in clinical trials against hematological cancers, but has experienced challenges in the treatment of solid tumors. One of the main difficulties lies in a paucity of tumor-specific targets that can serve as CAR recognition domains. We therefore focused on developing VHH-based, single-domain antibody (nanobody) CAR T cells that target aspects of the tumor microenvironment conserved across multiple cancer types. Many solid tumors evade immune recognition through expression of checkpoint molecules, such as PD-L1, that down-regulate the immune response. We therefore targeted CAR T cells to the tumor microenvironment via the checkpoint inhibitor PD-L1 and observed a reduction in tumor growth, resulting in improved survival. CAR T cells that target the tumor stroma and vasculature through the EIIIB⁺ fibronectin splice variant, which is expressed by multiple tumor types and on neovasculature, are likewise effective in delaying tumor growth. VHH-based CAR T cells can thus function as antitumor agents for multiple targets in syngeneic, immunocompetent animal models. Our results demonstrate the flexibility of VHH-based CAR T cells and the potential of CAR T cells to target the tumor microenvironment and treat solid tumors.

Metabolism, pharmacokinetics, and hepatic disposition of xanthones and saponins on Zhimu treatments for exploratively interpreting the discrepancy between the herbal safety and timosaponin A3-induced hepatotoxicity

Timosaponin A3, a saponin in Zhimu, elicited hepatotoxicity via oxidative stress. However, the clinical medication of Zhimu has been historically regarded as safe, probably associated with the antioxidants it contains. However, the related information on the in vivo levels of timosaponin A3 and antioxidants remained unclear on Zhimu treatments. Therefore, a combination of the in vitro metabolism, including microbiota-mediated and liver-mediated metabolism, and in vivo pharmacokinetics and hepatic disposition, was conducted for three xanthones (neomangiferin, mangiferin, and norathyriol) and three saponins (timosaponin B2, timosaponin B3, and timosaponin A3) on Zhimu treatments. Consequently, following oral administration of Zhimu decoction to rats, those saponins and xanthones were all observed in the plasma with severe liver first-pass effect, where mangiferin was of the maximum exposure. Despite the ignorable content in the herb, timosaponin A3 elicited sizable hepatic exposure as the microbiota-mediated metabolite of saponins in Zhimu. The similar phenomenon also occurred to norathyriol, the microbiota-mediated metabolite of xanthones. However, the major prototypes in Zhimu were of limited hepatic exposure. We deduced the hepatic collection of norathyriol, maximum circulating levels of mangiferin, and timosaponin B2 and mangiferin interaction may directly or indirectly contribute to the whole anti-oxidation of Zhimu, and then resisted the timosaponin A3-induced hepatotoxicity. Thus, our study exploratively interpreted the discrepancy between herbal safety and timosaponin A3-induced hepatotoxicity. However, given the considerable levels and slow eliminated rate of timosaponin A3 in the liver, more attention should be paid to the safety on the continuous clinical medication of Zhimu in the future.

The requirement for immune infiltration and organization in the tumor microenvironment for successful immunotherapy in prostate cancer

Immunotherapy-particularly immune checkpoint blockade-has seen great success in many tumor types. However, checkpoint-based therapies have not demonstrated high levels of success in prostate cancer, and there is much to be learned from both the successes and failures of these treatments. Here we review the evidence that composition of infiltrating immune cells in the tumor microenvironment is fundamental to the response to immunotherapy. Additionally, we discuss the emerging idea that the organization of these immune cells may also be crucial to this response. In prostate cancer, the composition and organization of the tumor immune microenvironment are preeminent topics of discussion and areas of important future investigation.

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.

[Immunotherapy for the treatment of prostate cancer-a comeback?]

BACKGROUND

Prostate cancer (PCA) seems to be more of an immunologic desert than other tumor entities. It is striking that only rarely does prostate cancer show abundant immune cells and a proimmunogenic microenvironment.

OBJECTIVES

Is immunotherapy in PCA effective and which patients can benefit.

MATERIALS AND METHODS

A review of the literature and recent congress data are presented.

RESULTS

Preliminary results with sipuleucel-T for PCA cancer were very promising showing a significant overall survival benefit in randomised phase III studies and the US Federal Drug Administration (FDA) approval for this individualised vaccine. Contrary to other tumor entities this was not the immediate breakthrough to a new therapeutic era of immunotherapy but remained an isolated case and restricted to the USA. More recently, several trials evaluated immunotherapeutic agents but missed their preliminary endpoints. Interestingly, individual patients did benefit and showed long-term remission.

CONCLUSIONS

Genome sequencing and new biomarkers are also paving a novel pathway towards individualised immunotherapy for PCA. On-going research and clinical trials are exploring the question of which patients will benefit.

Comparisons of therapeutic efficacy and safety of ipilimumab plus GM-CSF versus ipilimumab alone in patients with cancer: a meta-analysis of outcomes

Background

Recent clinical studies have shown that initial therapy with combined cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) blockade and granulocyte-macrophage colony-stimulating factor (GM-CSF)-based immunotherapies can enhance the antitumor efficacy of this approach. A key unanswered question is whether systemic GM-CSF enhances CTLA-4 blockade. Thus, the objective of this study was taking a meta-analysis of randomized controlled trials to compare the effect of ipilimumab plus GM-CSF versus ipilimumab alone on overall response, overall survival, and progression-free survival, as well as the risk of adverse events (AEs) in patients with cancer.

Materials and methods

Searches were made in electronic databases PubMed and Embase, and conference abstracts published by the American Society of Clinical Oncology from 2000 to 2017. Statistical analyses were carried out using either random-effects or fixed-effects models according to the heterogeneity of eligible studies.

Results

Six trials comprising of 445 patients were included in the meta-analysis. Combination group was superior to the ipilimumab alone in overall response rate, progression-free survival, and overall survival rate (combined relative risk [RR]=1.34, 95% CI: 1.24–1.45, P=0.09; combined hazard ratio [HR]=0.57, 95% CI: 0.32–1.02, P=0.06; combined HR=0.70, 95% CI: 0.60–0.82, P<0.001). Patients with combination therapies had a lower incidence of AEs including high-grade diarrhea (combined RR=0.27, 95% CI: 0.11–0.70, P=0.007), nausea (combined RR=0.25, 95% CI: 0.07–0.89, P=0.03), colitis (combined RR=0.34, 95% CI: 0.13–0.86, P=0.02), and fatigue (combined RR=0.91, 95% CI: 0.37–2.2.3, P=0.84) compared to the group having ipilimumab alone.

Conclusion

These data suggested that the combination of ipilimumab and GM-CSF was associated with a significant improvement in overall survival and lower high-grade toxicities, but there is no difference in overall response rate and progression-free survival among the cancer patients. Therefore, large-scale and well-designed studies are needed to summarize and analyze the data to draw a more convincing conclusion.

Expression analysis of cancer-testis genes in prostate cancer reveals candidates for immunotherapy

Prostate cancer is a prevalent disorder among men with a heterogeneous etiological background. Several molecular events and signaling perturbations have been found in this disorder. Among genes whose expressions have been altered during the prostate cancer development are cancer-testis antigens (CTAs). This group of antigens has limited expression in the normal adult tissues but aberrant expression in cancers. This property provides them the possibility to be used as cancer biomarkers and immunotherapeutic targets. Several CTAs have been shown to be immunogenic in prostate cancer patients and some of the have entered clinical trials. Based on the preliminary data obtained from these trials, it is expected that CTA-based therapeutic options are beneficial for at least a subset of prostate cancer patients.

NY-ESO-1 Based Immunotherapy of Cancer: Current Perspectives

NY-ESO-1 or New York esophageal squamous cell carcinoma 1 is a well-known cancer-testis antigen (CTAs) with re-expression in numerous cancer types. Its ability to elicit spontaneous humoral and cellular immune responses, together with its restricted expression pattern, have rendered it a good candidate target for cancer immunotherapy. In this review, we provide background information on NY-ESO-1 expression and function in normal and cancerous tissues. Furthermore, NY-ESO-1-specific immune responses have been observed in various cancer types; however, their utility as biomarkers are not well determined. Finally, we describe the immune-based therapeutic options targeting NY-ESO-1 that are currently in clinical trial. We will highlight the recent advancements made in NY-ESO-1 cancer vaccines, adoptive T cell therapy, and combinatorial treatment with checkpoint inhibitors and will discuss the current trends for future NY-ESO-1 based immunotherapy. Cancer treatment has been revolutionized over the last few decades with immunotherapy emerging at the forefront. Immune-based interventions have shown promising results, providing a new treatment avenue for durable clinical responses in various cancer types. The majority of successful immunotherapy studies have been reported in liquid cancers, whereas these approaches have met many challenges in solid cancers. Effective immunotherapy in solid cancers is hampered by the complex, dynamic tumor microenvironment that modulates the extent and phenotype of the antitumor immune response. Furthermore, many solid tumor-associated antigens are not private but can be found in normal somatic tissues, resulting in minor to detrimental off-target toxicities. Therefore, there is an ongoing effort to identify tumor-specific antigens to target using various immune-based modalities. CTAs are considered good candidate targets for immunotherapy as they are characterized by a restricted expression in normal somatic tissues concomitant with a re-expression in solid epithelial cancers. Moreover, several CTAs have been found to induce a spontaneous immune response, NY-ESO-1 being the most immunogenic among the family members. Hence, this review will focus on NY-ESO-1 and discuss the past and current NY-ESO-1 targeted immunotherapeutic strategies.

Cancer immunotherapy: new applications in urologic oncology

PURPOSE OF REVIEW

Immunotherapy in urological cancer has made substantial progress during the last 20 years, but recent advances in immunotherapy have completely transformed the present treatment landscape. In this review, we summarize major clinical achievements of immunotherapy in genitourinary cancers, as well as address potential new directions for these therapies, including new agents, combinations, and biomarkers.

RECENT FINDINGS

Recently, nivolumab and atezolizumab have joined sipuleucel-T as Food and Drug Administration-approved therapies in urological malignancies. Additional checkpoint inhibitors and vaccines are being tested in clinical trials. Furthermore, significant work has been done exploring predictors of response to therapy.

SUMMARY

Immunotherapy has changed the treatment of urologic malignancies. New immunotherapies and novel combinations will continue to create new treatment options in urologic tumors.

Shuffling the deck with CTLA-4 therapy: Deep sequencing of rearranged TCRB genes demonstrates T cell repertoire remodeling in cancer patients

CTLA-4 inhibition produces durable T cell-driven antitumor responses, but understanding which patients achieve a long-term benefit remains unclear. Deep sequencing of rearranged T cell receptor β (TCRβ) genes can monitor the effects of CTLA-4 inhibition and potentially identify patients with long-term survival.

Robust Antitumor Responses Result from Local Chemotherapy and CTLA-4 Blockade

Clinical responses to immunotherapy have been associated with augmentation of preexisting immune responses, manifested by heightened inflammation in the tumor microenvironment. However, many tumors have a noninflamed microenvironment, and response rates to immunotherapy in melanoma have been <50%. We approached this problem by utilizing immunotherapy (CTLA-4 blockade) combined with chemotherapy to induce local inflammation. In murine models of melanoma and prostate cancer, the combination of chemotherapy and CTLA-4 blockade induced a shift in the cellular composition of the tumor microenvironment, with infiltrating CD8⁺ and CD4⁺ T cells increasing the CD8/Foxp3 T-cell ratio. These changes were associated with improved survival of the mice. To translate these findings into a clinical setting, 26 patients with advanced melanoma were treated locally by isolated limb infusion with the nitrogen mustard alkylating agent melphalan followed by systemic administration of CTLA-4 blocking antibody (ipilimumab) in a phase II trial. This combination of local chemotherapy with systemic checkpoint blockade inhibitor resulted in a response rate of 85% at 3 months (62% complete and 23% partial response rate) and a 58% progression-free survival at 1 year. The clinical response was associated with increased T-cell infiltration, similar to that seen in the murine models. Together, our findings suggest that local chemotherapy combined with checkpoint blockade-based immunotherapy results in a durable response to cancer therapy. Cancer Immunol Res; 6(2); 189-200. ©2018 AACR.

Current Role of Checkpoint Inhibitors in Urologic Cancers

Harnessing the host immune system to combat genitourinary cancers has key theoretical advantages over other anticancer strategies including specificity and memory which should translate to favorable tolerability and response durability in the clinic. Indeed, key examples of the potential for immunotherapeutic treatment of solid tumors are derived from data in genitourinary cancers including Bacillus Calmette-Guerin for urothelial cancer, sipuleucel-T for prostate cancer, and interleukin-2 for renal cancer. Despite these successes, developing effective immunotherapeutic strategies for the treatment of cancer has largely been hampered by an incomplete understanding of tumor immunobiology and mechanisms of immune resistance. In just a few years since entering the clinic, immune checkpoint blockade has dramatically changed the landscaped of treatment for genitourinary cancer and has secured a place as a standard pillar of treatment. Further iterative bench-bedside-bench research is anticipated to extend the benefits of immunotherapeutic-based approaches to additional patients.

Ipilimumab for the treatment of metastatic prostate cancer

INTRODUCTION

Immunotherapy with checkpoint inhibitors is beginning to be recognized as a valid weapon for the treatment of metastatic prostate cancer (PCa) when chemotherapy fails. Ipilimumab (ipi) is a fully humanized monoclonal antibody that blocks the activity of CTLA4. It also has a molecular weight of 148 kDa and is water-soluble at physiological pH. Ipi was first approved by the FDA for the treatment of malignant melanoma and is currently being studied in metastatic castration-resistant prostate cancer, with promising early results. Areas covered: The aim of this review is to collate the most significant preclinical and clinical studies available that look at ipi to propose new strategies for the future. Expert opinion: Additional studies are required to reduce toxicity and increase the activity of ipi in PCa. A possible strategy is to combine ipi with standard anti-cancer therapeutics such as vaccines, PDL1 inhibitors, antiandrogen drugs, and chemotherapy agents. Several initial results have suggested that combination strategies are useful to increase the activity in mCRPC, even if the toxicity of the treatment can increase. The activity of combined treatments is still not predictable, but considering the ongoing studies, we believe that they have good potential that will lead to the discovery of an optimal therapeutic strategy.

Strategies to Improve Vaccine Efficacy against Tuberculosis by Targeting Innate Immunity

The global tuberculosis epidemic is the most common cause of death after infectious disease worldwide. Increasing numbers of infections with multi- and extensively drug-resistant variants of the Mycobacterium tuberculosis complex, resistant even to newly discovered and last resort antibiotics, highlight the urgent need for an efficient vaccine. The protective efficacy to pulmonary tuberculosis in adults of the only currently available vaccine, M. bovis BCG, is unsatisfactory and geographically diverse. More importantly, recent clinical studies on new vaccine candidates did not prove to be better than BCG, yet. Here, we propose and discuss novel strategies to improve efficacy of existing anti-tuberculosis vaccines. Modulation of innate immune responses upon vaccination already provided promising results in animal models of tuberculosis. For instance, neutrophils have been shown to influence vaccine efficacy, both, positively and negatively, and stimulate specific antibody secretion. Modulating immune regulatory properties after vaccination such as induction of different types of innate immune cell death, myeloid-derived suppressor or regulatory T cells, production of anti-inflammatory cytokines such as IL-10 may have beneficial effects on protection efficacy. Incorporation of lipid antigens presented via CD1 molecules to T cells have been discussed as a way to enhance vaccine efficacy. Finally, concepts of dendritic cell-based immunotherapies or training the innate immune memory may be exploitable for future vaccination strategies against tuberculosis. In this review, we put a spotlight on host immune networks as potential targets to boost protection by old and new tuberculosis vaccines.

Targeting T Cell Co-receptors for Cancer Therapy

Checkpoint-blocking antibodies can generate potent anti-tumor responses by encouraging the immune system to seek and destroy cancer cells. At this time, the United States Food and Drug Administration has approved three checkpoint-blocking antibodies in three disease indications, and additional approvals are expected to broaden the clinical scope of immunotherapy. Herein, we review the clinical development of CTLA-4-, PD-1-, and PD-L1-blocking antibodies across tumor types and briefly discuss areas of active investigation of potential biomarkers.

Checkpoint inhibitors in the treatment of urological malignancies

Checkpoint inhibitors are monoclonal antibodies attach to several different receptors on T-cells or tumour cells expressing receptors for cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed death-1 (PD-1) and their ligand (PD-L1). Since 2010, numerous trials on different tumour types have been conducted, which was resulted in these drugs being approved for the treatment of melanoma, lung cancer, Hodgkin's lymphoma and head and neck cancers. Urological cancers, especially urothelial and renal-cell carcinomas, are immunogenic tumours. Since the late 70s, the bacillus Calmette-Gurin (BCG) vaccine has been used for intravesical instillation in non-muscle invasive bladder cancer from the mid-90s up until the discovery of tyrosine kinase inhibitors (TKIs) in 2007, interleukin-2 (IL-2) and interferon alpha (IFNα), which were the standard of care for metastatic renal-cell cancer. Two checkpoint inhibitors are already approved by the Food and Drug Administration: atezolizumab for metastatic urothelial cancer and nivolumab for metastatic renal-cell carcinoma. There are many drugs are in different phases of clinical development. Here we review the current status of checkpoint inhibitors in the treatment of urological tumours.

Cellular determinants and microenvironmental regulation of prostate cancer metastasis

Metastasis causes more than 90% of cancer-related deaths and most prostate cancer (PCa) patients also die from metastasis. The 'metastatic cascade' is a complex biological process that encompasses tumor cell dissociation (from the primary tumor), local invasion, intravasation, transport in circulation, extravasation, colonization, and overt growth in end organs. It has become clear that successful metastasis not only involves many tumor cell-intrinsic properties but also depends on productive interactions between cancer cells and the tumor microenvironment. In this Review, we begin with a general summary on cancer metastasis and a specific discussion on PCa metastasis. We then discuss recent advances in our knowledge of the cellular determinants of PCa metastasis and the importance of tumor microenvironment, especially an immunosuppressive tumor microenvironment, in shaping metastatic propensities. We conclude with a presentation of current and future therapeutic options for patients with PCa metastasis, emphasizing the development of novel, mechanism-based combinatorial strategies for treating metastatic and castration-resistant PCa.

Systematic evaluation of immune regulation and modulation

Cancer immunotherapies are showing promising clinical results in a variety of malignancies. Monitoring the immune as well as the tumor response following these therapies has led to significant advancements in the field. Moreover, the identification and assessment of both predictive and prognostic biomarkers has become a key component to advancing these therapies. Thus, it is critical to develop systematic approaches to monitor the immune response and to interpret the data obtained from these assays. In order to address these issues and make recommendations to the field, the Society for Immunotherapy of Cancer reconvened the Immune Biomarkers Task Force. As a part of this Task Force, Working Group 3 (WG3) consisting of multidisciplinary experts from industry, academia, and government focused on the systematic assessment of immune regulation and modulation. In this review, the tumor microenvironment, microbiome, bone marrow, and adoptively transferred T cells will be used as examples to discuss the type and timing of sample collection. In addition, potential types of measurements, assays, and analyses will be discussed for each sample. Specifically, these recommendations will focus on the unique collection and assay requirements for the analysis of various samples as well as the high-throughput assays to evaluate potential biomarkers.