Limitations and opportunities for immune checkpoint inhibitors in pediatric malignancies

Pt-Te-Nanorod-Based Photothermal Chemokine Immunotherapy for All Stages of Cancer via Adaptive and Innate Immunity

The chemokine (C-X-C) motif ligand 9 (CXCL9) is one of the lymphocyte-traffic-involved chemokines. Despite the immunotherapeutic potential of CXCL9 for recruiting effector T cells (cluster of differentiation 4+ (CD4+) and CD8+ T cells) and natural killer cells (NK cells) around the tumors, practical applications of CXCL9 have been limited because of its immune toxicity and lack of stability in vivo. To overcome these limitations, we designed and synthesized Pt-Te nanorods (PtTeNRs), which exhibited excellent photothermal conversion efficiency with stable CXCL9 payload characteristics under the physiological conditions of in vivo environments. We developed a CXCL9-based immunotherapy strategy by utilizing the unique physicochemical properties of developed PtTeNRs. The investigation revealed that the PtTeNR-loaded CXCL9 was effectively accumulated in the tumor, subsequently released in a sustained manner, and successfully recruited effector T cells for immunotherapy of the designated tumor tissue. In addition, a synergistic effect was observed between the photothermal (PT) therapy and antiprogrammed cell death protein 1 (aPD-1) antibody. In this study, we demonstrated that PtTeNR-based CXCL9, PT, and aPD-1 antibody trimodal therapy delivers an outstanding tumor suppression effect in all stages of cancer, including phases 1-4 and tumor recurrence.

From immunomodulation to therapeutic prospects: Unveiling the biology of butyrophilins in cancer

Butyrophilin (BTN) proteins are a type of membrane protein that belongs to the Ig superfamily. They exhibit a high degree of structural similarity to molecules in the B7 family. They fulfill a complex function in regulating immune responses, including immunomodulatory roles, as they influence γδ T cells. The biology of BTN molecules indicates that they are capable of inhibiting the immune system's ability to detect antigens within tumors. A dynamic association between BTN molecules and cellular surfaces is also recognized in specific contexts, influencing their biology. Notably, the dynamism of BTN3A1 is associated with the immunosuppression of T cells or the activation of Vγ9Vδ2 T cells. Cancer immunotherapy relies heavily on T cells to modulate immune function within the intricate interaction of the tumor microenvironment (TME). A significant interaction between the TME and antitumor immunity involves the presence of BTN, which should be taken into account when developing immunotherapy. This review explores potential therapeutic applications of BTN molecules, based on the current understanding of their biology.

Polymer-based antibody mimetics (iBodies) target human PD-L1 and function as a potent immune checkpoint blocker

Immune checkpoint blockade (ICB) using monoclonal antibodies against programmed cell death protein 1 (PD-1) or programmed death-ligand 1 (PD-L1) is the treatment of choice for cancer immunotherapy. However, low tissue permeability, immunogenicity, immune-related adverse effects, and high cost could be possibly improved using alternative approaches. On the other hand, synthetic low-molecular-weight (LMW) PD-1/PD-L1 blockers have failed to progress beyond in vitro studies, mostly due to low binding affinity or poor pharmacological characteristics resulting from their limited solubility and/or stability. Here, we report the development of polymer-based anti-human PD-L1 antibody mimetics (α-hPD-L1 iBodies) by attaching the macrocyclic peptide WL12 to a N-(2-hydroxypropyl)methacrylamide copolymer. We characterized the binding properties of iBodies using surface plasmon resonance, enzyme-linked immunosorbent assay, flow cytometry, confocal microscopy, and a cellular ICB model. We found that the α-hPD-L1 iBodies specifically target human PD-L1 (hPD-L1) and block the PD-1/PD-L1 interaction in vitro, comparable to the atezolizumab, durvalumab, and avelumab licensed monoclonal antibodies targeting PD-L1. Our findings suggest that iBodies can be used as experimental tools to target hPD-L1 and could serve as a platform to potentiate the therapeutic effect of hPD-L1-targeting small molecules by improving their affinity and pharmacokinetic properties.

TLR5 agonist in combination with anti-PD-1 treatment enhances anti-tumor effect through M1/M2 macrophage polarization shift and CD8+ T cell priming

Immune checkpoint inhibitors have revolutionized anti-tumor therapy, notably improving treatment responses in various tumors. However, many patients remain non-responsive and do not experience benefits. Given that Toll-like receptors (TLRs) can counteract tumor immune tolerance by stimulating both innate and adaptive immune responses, TLR agonists are being explored as potential immune adjuvants for cancer treatment. In this study, we assessed the potential of enhancing the efficacy of immune checkpoint inhibitors by activating innate immunity with a TLR5 agonist. In a mouse tumor model, combination therapy with TLR5 agonist and anti-PD-1 significantly inhibited tumor growth. The TLR5 agonist shifted the balance from M2-like to M1-like macrophages and upregulated the expression of co-stimulatory molecules in macrophages. Furthermore, TLR5 agonist promoted the activation and tumor infiltration of CD8+ T cells. As a result, the TLR5 agonist augmented the anti-tumor efficacy of anti-PD-1, suggesting its potential in modulating the tumor microenvironment to enhance the anti-tumor response. Our findings point toward the possibility of optimizing immune checkpoint inhibitor therapy using TLR5 agonists.

Cell-mediated barriers in cancer immunosurveillance

The immune cells within the tumor microenvironment (TME) exert multifaceted functions ranging from tumor-antagonizing or tumor-promoting activities. During the initial phases of tumor development, the tumor-antagonizing immune cells in the TME combat cancer cells in an immune surveillance process. However, with time, cancer cells can evade detection and impede the immune cells' effectiveness through diverse mechanisms, such as decreasing immunogenic antigen presentation on their surfaces and/or secreting anti-immune factors that cause tolerance in TME. Moreover, some immune cells cause immunosuppressive situations and inhibit antitumoral immune responses. Physical and cellular-mediated barriers in the TME, such as cancer-associated fibroblasts, tumor endothelium, the altered lipid composition of tumor cells, and exosomes secreted from cancer cells, also mediate immunosuppression and prevent extravasation of immune cells. Due to successful clinical outcomes of cancer treatment strategies the potential barriers must be identified and addressed. We need to figure out how to optimize cancer immunotherapy strategies, and how to combine therapeutic approaches for maximum clinical benefit. This review provides a detailed overview of various cells and molecules in the TME, their association with escaping from immune surveillance, therapeutic targets, and future perspectives for improving cancer immunotherapy.

Immune checkpoint inhibitors therapy as the game-changing approach for pediatric lymphoma: A brief landscape

Lymphoma is known as the third most common malignancy in children, and its prevalence and mortality are increasing. Common treatments, including chemotherapy, radiotherapy, and also surgery, despite their efficacy, have many side effects and, have a high chance of disease relapse. Immune Checkpoint Inhibitors (ICIs) offer a promising alternative with potentially fewer risks of relapse and toxicity. This review article aims to investigate the efficacy and safety of ICIs, either as monotherapy or in combination, for pediatric lymphoma patients. ICIs have revolutionized cancer treatment in recent years and have shown remarkable results in several adult cancers. However, their efficacy in treating pediatrics requires further investigation. Nevertheless, some ICIs, including nivolumab, pembrolizumab, and ipilimumab, have demonstrated encouraging outcomes. ICIs therapy is not without risks and can cause side effects, including rash, itching, vitiligo, abdominal pain, diarrhea, dysphagia, epigastric pain, nausea, vomiting, thyroid, and pituitary dysfunction. Overall, this review article highlights the potential benefits and risks of ICIs in treating pediatric lymphoma.

Update on immune-based therapy strategies targeting cancer stem cells

Accumulating data reveals that tumors possess a specialized subset of cancer cells named cancer stem cells (CSCs), responsible for metastasis and recurrence of malignancies, with various properties such as self-renewal, heterogenicity, and capacity for drug resistance. Some signaling pathways or processes like Notch, epithelial to mesenchymal transition (EMT), Hedgehog (Hh), and Wnt, as well as CSCs' surface markers such as CD44, CD123, CD133, and epithelial cell adhesion molecule (EpCAM) have pivotal roles in acquiring CSCs properties. Therefore, targeting CSC-related signaling pathways and surface markers might effectively eradicate tumors and pave the way for cancer survival. Since current treatments such as chemotherapy and radiation therapy cannot eradicate all of the CSCs and tumor relapse may happen following temporary recovery, improving novel and more efficient therapeutic options to combine with current treatments is required. Immunotherapy strategies are the new therapeutic modalities with promising results in targeting CSCs. Here, we review the targeting of CSCs by immunotherapy strategies such as dendritic cell (DC) vaccines, chimeric antigen receptors (CAR)-engineered immune cells, natural killer-cell (NK-cell) therapy, monoclonal antibodies (mAbs), checkpoint inhibitors, and the use of oncolytic viruses (OVs) in pre-clinical and clinical studies. This review will mainly focus on blood malignancies but also describe solid cancers.

Promise and Challenges of T Cell Immunotherapy for Osteosarcoma

The cure rate for metastatic or relapsed osteosarcoma has not substantially improved over the past decades despite the exploitation of multimodal treatment approaches, allowing long-term survival in less than 30% of cases. Patients with osteosarcoma often develop resistance to chemotherapeutic agents, where personalized targeted therapies should offer new hope. T cell immunotherapy as a complementary or alternative treatment modality is advancing rapidly in general, but its potential against osteosarcoma remains largely unexplored. Strategies incorporating immune checkpoint inhibitors (ICIs), chimeric antigen receptor (CAR) modified T cells, and T cell engaging bispecific antibodies (BsAbs) are being explored to tackle relapsed or refractory osteosarcoma. However, osteosarcoma is an inherently heterogeneous tumor, both at the intra- and inter-tumor level, with no identical driver mutations. It has a pro-tumoral microenvironment, where bone cells, stromal cells, neovasculature, suppressive immune cells, and a mineralized extracellular matrix (ECM) combine to derail T cell infiltration and its anti-tumor function. To realize the potential of T cell immunotherapy in osteosarcoma, an integrated approach targeting this complex ecosystem needs smart planning and execution. Herein, we review the current status of T cell immunotherapies for osteosarcoma, summarize the challenges encountered, and explore combination strategies to overcome these hurdles, with the ultimate goal of curing osteosarcoma with less acute and long-term side effects.

Intratumoral erythroblastic islands restrain anti-tumor immunity in hepatoblastoma

Erythroblastic islands (EBIs) are the specialized structures for erythropoiesis, but they have never been found functional in tumors. As the most common pediatric liver malignancy, hepatoblastoma (HB) requires more effective and safer therapies to prevent progression and the lifelong impact of complications on young children. However, developing such therapies is impeded by a lack of comprehensive understanding of the tumor microenvironment. By single-cell RNA sequencing of 13 treatment-naive HB patients, we discover an immune landscape characterized by aberrant accumulation of EBIs, formed by VCAM1⁺ macrophages and erythroid cells, which is inversely correlated with survival of HB. Erythroid cells inhibit the function of dendritic cells (DCs) via the LGALS9/TIM3 axis, leading to impaired anti-tumor T cell immune responses. Encouragingly, TIM3 blockades relieve the inhibitory effect of erythroid cells on DCs. Our study provides an immune evasion mechanism mediated by intratumoral EBIs and proposes TIM3 as a promising therapeutic target for HB.

CAR T-Cell Therapy in Children with Solid Tumors

The limited efficacy of traditional cancer treatments, including chemotherapy, radiotherapy, and surgery, emphasize the significance of employing innovative methods. CAR (Chimeric Antigen Receptor) T-cell therapy remains the most revolutionizing treatment of pediatric hematological malignancies and solid tumors. Patient’s own lymphocytes are modified ex-vivo using gene transfer techniques and programmed to recognize and destroy specific tumor cells regardless of MHC receptor, which probably makes CAR-T the most personalized therapy for the patient. With continued refinement and optimization, CAR-T cell therapy has the potential to significantly improve outcomes and quality of life for children with limited treatment options. It has shown remarkable success in treating hematological malignancies, such as acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL). However, its effectiveness in treating solid tumors is still being investigated and remains an area of active research. In this review we focus on solid tumors and explain the concept of CAR modified T cells, and discuss some novel CAR designs that are being considered to enhance the safety of CAR T-cell therapy in under-mentioned cancers. Furthermore, we summarize the most crucial recent reports concerning the solid tumors treatment in children. In the end we provide a short summary of many challenges that limit the therapeutic efficacy of CAR-T in solid tumors, such as antigen escape, immunosuppressive microenvironment, poor trafficking, and tumor infiltration, on-target off-tumor effects and general toxicity.

Thyroid dysfunction during treatment with systemic antineoplastic therapy for childhood cancer: A systematic review

Thyroid dysfunction is known to occur following radiotherapy or chemotherapy for childhood cancer. Thyroid dysfunction during treatment for childhood cancer has, however, not been studied extensively, although thyroid hormones are of utmost importance during childhood. This information is needed to develop adequate screening protocols and may be of special importance with upcoming drugs, such as checkpoint inhibitors, which are highly associated with thyroid dysfunction in adults. In this systematic review we have evaluated the occurrence and risk factors for thyroid dysfunction in children during treatment with systemic antineoplastic drugs, up to three months after the end of therapy. Two review authors independently performed the study selection, data extraction and risk of bias assessment of included studies. After an extensive search (January 2021), in total six heterogeneous articles were included, reporting on 91 childhood cancer patients with a thyroid function test during treatment with systemic antineoplastic therapy for childhood cancer. All studies had risk of bias issues. Primary hypothyroidism was found in 18% of children treated with high dose interferon-α (HDI-α) and in 0-10% after tyrosine kinase inhibitors (TKIs). Transient euthyroid sick syndrome (ESS) was common (in 42-100%) during treatment with systematic multi-agent chemotherapy. Only one study addressed possible risk factors, showing different types of treatment to increase the risk. However, the exact prevalence, risk factors and clinical consequences of thyroid dysfunction remain unclear. Prospective high-quality studies including large study samples are needed to longitudinally assess the prevalence, risk factors and possible consequences of thyroid dysfunction during childhood cancer treatment.

Head and Neck Cancer Immunotherapy: Molecular Biological Aspects of Preclinical and Clinical Research

Breakthrough research in the field of immune checkpoint inhibitors and the development of a human papilloma virus vaccine triggered a plethora of research in the field of cancer immunotherapy. Both had significant effects on the treatment of head and neck squamous cell carcinoma. The advent of preclinical models and multidisciplinary approaches including bioinformatics, genetic engineering, clinical oncology, and immunology helped in the development of tumour-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR) T-cell therapy. Here, we discuss different immunotherapies such as adoptive T-cell transfer, immune checkpoint inhibitors, interleukins, and cancer vaccines for the treatment of head and neck cancer. This review showcases the intrinsic relation between the understanding and implementation of basic biology and clinical practice. We also address potential limitations of each immunotherapy approach and the advantages of personalized immunotherapy. Overall, the aim of this review is to encourage further research in the field of immunotherapy for head and neck cancer.

The peculiar challenge of bringing CAR-T cells into the brain: Perspectives in the clinical application to the treatment of pediatric central nervous system tumors

Childhood malignant brain tumors remain a significant cause of death in the pediatric population, despite the use of aggressive multimodal treatments. New therapeutic approaches are urgently needed for these patients in order to improve prognosis, while reducing side effects and long-term sequelae of the treatment. Immunotherapy is an attractive option and, in particular, the use of gene-modified T cells expressing a chimeric antigen receptor (CAR-T cells) represents a promising approach. Major hurdles in the clinical application of this approach in neuro-oncology, however, exist. The peculiar location of brain tumors leads to both a difficulty of access to the tumor mass, shielded by the blood-brain barrier (BBB), and to an increased risk of potentially life-threatening neurotoxicity, due to the primary location of the disease in the CNS and the low intracranial volume reserve. There are no unequivocal data on the best way of CAR-T cell administration. Multiple trials exploring the use of CD19 CAR-T cells for hematologic malignancies proved that genetically engineered T cells can cross the BBB, suggesting that systemically administered CAR-T cell can be used in the neuro-oncology setting. Intrathecal and intra-tumoral delivery can be easily managed with local implantable devices, suitable also for a more precise neuro-monitoring. The identification of specific approaches of neuro-monitoring is of utmost importance in these patients. In the present review, we highlight the most relevant potential challenges associated with the application of CAR-T cell therapy in pediatric brain cancers, focusing on the evaluation of the best route of delivery, the peculiar risk of neurotoxicity and the related neuro-monitoring.

BTN3A: A Promising Immune Checkpoint for Cancer Prognosis and Treatment

Butyrophilin-3A (BTN3A) subfamily members are a group of immunoglobulins present on the surface of different cell types, including innate and cancer cells. Due to their high similarity with the B7 family members, different studies have been conducted and revealed the involvement of BTN3A molecules in modulating T cell activity within the tumor microenvironment (TME). However, a great part of this research focused on γδ T cells and how BTN3A contributes to their functions. In this review, we will depict the roles and various aspects of BTN3A molecules in distinct tumor microenvironments and review how BTN3A receptors modulate diverse immune effector functions including those of CD4+ (Th1), cytotoxic CD8+ T cells, and NK cells. We will also highlight the potential of BTN3A molecules as therapeutic targets for effective immunotherapy and successful cancer control, which could represent a bright future for patient treatment.

Nanotherapeutics for immune network modulation in tumor microenvironments

Immunotherapy has shown promise in cancer treatment, and is thus drawing increasing interest in this field. While the standard chemotherapy- and/or radiotherapy-based cancer treatments aim to directly kill cancer cells, immunotherapy uses host immune cell surveillance to fight cancer. In the tumor environment, there is a close relationship between tumor cells and the adjacent immune cells, which are largely suppressed by cancer-related regulation of immune checkpoints, immune-suppressive cytokines, and metabolic factors. The immune modulators currently approved for cancer treatment remain limited by issues with dose tolerance and insufficient efficacy. Researchers have developed and tested various nano-delivery systems with the goal of improving the treatment outcome of these drugs. By encapsulating immune modulators in particles and directing their tissue accumulation, some such systems have decreased immune-related toxicity while sharpening the antitumor response. Surface-ligand modification of nanoparticles has allowed drugs to be delivered to specific immune cells types. Researchers have also studied strategies for depleting or reprogramming the immune-suppressive cells to recover the immune environment. Combining a nanomaterial with an external stimulus has been used to induce immunogenic cell death; this favors the inflammatory environment found in tumor tissues to promote antitumor immunity. The present review covers the most recent strategies aimed at modulating the tumor immune environment, and discusses the challenges and future perspectives in developing nanoparticles for cancer immunotherapy.

Effectiveness of combination therapy with ISA101 vaccine for the treatment of human papillomavirus-induced cervical cancer

Cervical cancer is one of the women-associated tumors that affects numerous people yearly. It is the fourth most common malignancy in women worldwide. Following early diagnosis, this cancer can be cured mainly by traditional methods such as surgery, tumor resection, and chemotherapy; nonetheless, it becomes more challenging to treat in advanced and metastatic stages. With the advent of novel treatments such as angiogenesis inhibitors or immuno-checkpoint blockers in recent years, the survival rate of patients with advanced cervical cancer has significantly increased. However, it has not yet reached a satisfactory level. It has been revealed that human papillomavirus (HPV) infection is responsible for more than 90% of cervical cancer cases. However, evidence revealed that monotherapy with anti-HPV vaccines such as ISA101 could not affect tumor growth and progression in patients with HPV-induced cervical cancer. Therefore, combining ISA101 and immune checkpoint blockers or other immunotherapeutic approaches may be more robust and effective than monotherapy with ISA101 or immune checkpoint blockers for treating cervical cancer. This review summarizes the ISA101 properties, advantages and disadvantages. Furthermore, various conducted combination therapies with ISA101 and the effectiveness and challenges of this treatment have been discussed.

A novel anti-B7-H3 chimeric antigen receptor from a single-chain antibody library for immunotherapy of solid cancers

B7-H3 (CD276) has emerged as a target for cancer immunotherapy by virtue of consistent expression in many malignancies, relative absence from healthy tissues, and an emerging role as a driver of tumor immune inhibition. Recent studies have reported B7-H3 to be a suitable target for chimeric antigen receptor-modified T cell (CAR-T) therapy using CARs constructed from established anti-B7-H3 antibodies converted into single-chain Fv format (scFv). We constructed and screened binders in an scFv library to generate a new anti-B7-H3 CAR-T with favorable properties. This allowed access to numerous specificities ready formatted for CAR evaluation. Selected anti-human B7-H3 scFvs were readily cloned into CAR-T and evaluated for anti-tumor reactivity in cytotoxicity, cytokine, and proliferation assays. Two binders with divergent complementarity determining regions were found to show optimal antigen-specific cytotoxicity and cytokine secretion. One binder in second-generation CD28-CD3ζ CAR format induced sustained in vitro proliferation on repeat antigen challenge. The lead candidate CAR-T also demonstrated in vivo activity in a resistant neuroblastoma model. An empirical approach to B7-H3 CAR-T discovery through screening of novel scFv sequences in CAR-T format has led to the identification of a new construct with sustained proliferative capacity warranting further evaluation.

Connecting telomere maintenance and regulation to the developmental origin and differentiation states of neuroblastoma tumor cells

A cardinal feature that distinguishes clinically high-risk neuroblastoma from low-risk tumors is telomere maintenance. Specifically, neuroblastoma tumors with either active telomerase or alternative lengthening of telomeres exhibit aggressive growth characteristics that lead to poor outcomes, whereas tumors without telomere maintenance can be managed with observation or minimal treatment. Even though the need for cancer cells to maintain telomere DNA-in order to sustain cell proliferation-is well established, recent studies suggest that the neural crest origin of neuroblastoma may enforce unique relationships between telomeres and tumor malignancy. Specifically in neuroblastoma, telomere structure and telomerase activity are correlated with the adrenergic/mesenchymal differentiation states, and manipulating telomerase activity can trigger tumor cell differentiation. Both findings may reflect features of normal neural crest development. This review summarizes recent advances in the characterization of telomere structure and telomere maintenance mechanisms in neuroblastoma and discusses the findings in the context of relevant literature on telomeres during embryonic and neural development. Understanding the canonical and non-canonical roles of telomere maintenance in neuroblastoma could reveal vulnerabilities for telomere-directed therapies with potential applications to other pediatric malignancies.

The role of anti-tumor immunity of focused ultrasound for the malignancies: depended on the different ablation categories

Improving anti-tumor immunity has promising outcomes in eradicating malignant tumors. Tumor cells can escape from immune surveillance and killing; therefore, various strategies are continuously developing to inhibit immune escape. Focused ultrasound (FUS) has recently emerged to play an important role in immune modulation. After FUS therapy, various tumor antigens and related signals are released. The non-thermal effect of FUS strengthens the blood and lymph circulation, increases cell permeability, and helps in crossing the physical barrier like the blood-brain barrier and blood-tumor barrier. However, the different ablation of FUS is proposed to have a different anti-tumor immune effect. Therefore, we categorized the FUS ablation into thermal and non-thermal ablation and summarized possible anti-tumor immunity mechanisms.

Polyendocrine Autoimmunity and Diabetic Ketoacidosis Following Anti-PD-1 and Interferon α

Immune checkpoint inhibitor (ICI) therapies are now first-line therapy for many advanced malignancies in adults, with emerging use in children. With increasing ICI use, prompt recognition and optimal management of ICI-associated immune-related adverse events (IRAEs) are critical. Nearly 60% of ICI-treated adults develop IRAEs, which commonly manifest as autoimmune skin, gastrointestinal, and endocrine disease and can be life-threatening. The incidence, presentation, and disease course of spontaneous autoimmune diseases differ between adults and children, but the pattern of pediatric IRAEs is currently unclear. We report a case of a pediatric patient presenting with new onset autoimmune diabetes mellitus and diabetic ketoacidosis during ICI treatment of fibrolamellar hepatocellular carcinoma (FLC). Distinct from spontaneous type 1 diabetes mellitus (T1DM), this patient progressed rapidly and was negative for known β cell autoantibodies. Additionally, the patient was positive for 21-hydroxylase autoantibodies, suggesting development of concomitant adrenal autoimmunity. Current guidelines for the management of IRAEs in adults may not be appropriate for the management of pediatric patients, who may have different autoimmune risks in a developmental context.

Antigen cross-presentation in young tumor-bearing hosts promotes CD8+ T cell terminal differentiation

The immune system undergoes a progressive functional remodeling with age. Understanding how age bias shapes antitumor immunity is essential in designing effective immunotherapies, especially for pediatric patients. Here, we explore antitumor CD8⁺ T cell responses generated in young (prepubescent) and adult (presenescent) mice. Using an MHCI-deficient tumor model, we observed that tumor-reactive CD8⁺ T cells expanded in young tumor-bearing (TB) mice acquired a terminally differentiated phenotype characterized by overexpression of inhibitory receptors and the transcription factor Tox1. Furthermore, tumor-infiltrating CD8⁺ T cells from young tumors yielded a poor cytokine response compared with CD8⁺ T cells infiltrating adult tumors. Young migratory dendritic cells (migDCs) from the draining lymph nodes (dLNs), and mononuclear phagocytic cells (MPCs) infiltrating young tumors, were more competent in capturing and cross-presenting tumor antigen, leading to enhanced priming of CD8⁺ T cells in dLNs and their subsequent terminal differentiation in the tumors. Single-cell transcriptional profiling of tumor-infiltrating MPCs demonstrated that young MPCs are polarized toward an inflammatory, effector phenotype. Consistent with our observations in young versus adult TB mice, analysis of immune infiltrates from pediatric solid tumors showed a correlation between tumor-infiltrating CD8⁺ T cells with an exhaustion phenotype and the frequency of PD-L1-expressing monocytes/macrophages. Collectively, these data indicate that a young tissue microenvironment contributes to the generation of an immune response skewed toward a less pliable terminal effector state, thus narrowing the window for immunotherapeutic interventions.

Expression of Immunomodulatory Checkpoint Molecules in Drug-Resistant Neuroblastoma: An Exploratory Study

Simple Summary

Neuroblastoma is a common childhood cancer with poor prognosis. Prior studies suggest that inhibition of molecules called checkpoint proteins, which normally prevent one’s own immune system from attacking itself, has been successfully used for treatment of multiple advanced adult cancers but has yet to be fully explored in neuroblastoma. Cancer can hijack these pathways to prevent the immune system from recognizing and destroying cancer cells. We investigated checkpoint protein expression in pediatric neuroblastoma and its role in drug resistance. We created drug-resistant neuroblastoma cell lines and compared expression of checkpoint proteins between drug-resistant and parental cell lines. In total, 13 checkpoint proteins were expressed by all cell lines regardless of drug resistance. Although PD-L1 and checkpoint proteins do not necessarily impart drug resistance, they may be potential targets for drug therapy. Benchmarking checkpoint proteins provides the basis for future studies identifying targets for directed therapy and biomarkers for cancer detection or prognosis.

Abstract

Neuroblastoma is a common childhood cancer with poor prognosis when at its advanced stage. Checkpoint molecule inhibition is successful in treating multiple advanced adult cancers. We investigated PD-L1 and other checkpoint molecule expression to determine their roles in drug resistance and usefulness as targets for drug therapy. We developed three doxorubicin-resistant (DoxR) cell lines from parental cell lines. Matrigel in vitro invasion assays were used to compare invasiveness. Western blot assays were used to compare PD-L1 expression. Immuno-oncology checkpoint protein panels were used to compare concentrations of 17 checkpoint molecules both cellular and soluble. PD-L1 and 12 other checkpoint molecules were present in all cell lysates of each cell line without significantly different levels. Three were solubilized in the media of each cell line. PD-L1 is expressed in all DoxR and parental neuroblastoma cells and may be a potential target for drug therapy although its role in drug resistance remains unclear. Benchmarking checkpoint molecules provides the basis for future studies identifying targets for directed therapy and biomarkers for cancer detection or prognosis.

Hybrid Membrane Nanovaccines Combined with Immune Checkpoint Blockade to Enhance Cancer Immunotherapy

Purpose

Cancer vaccines are a promising therapeutic approach in cancer immunotherapy and can inhibit tumor growth and prevent tumor recurrence and metastasis by activating a sustained antitumor immunoprotective effect. However, the therapeutic effect of cancer vaccines is severely weakened by the low immunogenicity of cancer antigens and the immunosuppressive microenvironment in tumor tissues.

Methods

Here, we report a novel hybrid membrane nanovaccine, composed of mesoporous silica nanoparticle as a delivery carrier, hybrid cell membranes obtained from dendritic cells and cancer cells, and R837 as an immune adjuvant (R837@HM-NPs). We investigated the anti-tumor, tumor recurrence and metastasis prevention abilities of R837@HM-NPs and their mechanisms of action through a series of in vivo and ex vivo experiments.

Results

R837@HM-NPs not only provide effective antigenic stimulation but are also a durable supply of the immune adjuvant R837. In addition, R837@HM-NPs promote antigen endocytosis into dendritic cells via various receptor-mediated pathways. Compared with HM-NPs or R837@HM-NPs, R837@HM-NPs in combination with an immune checkpoint blockade showed stronger antitumor immune responses in inhibiting tumor growth, thus eliminating established tumors, and rejecting re-challenged tumors by regulating the immunosuppressive microenvironment and immunological memory effect.

Conclusion

These findings suggest that the hybrid membrane nanovaccine in combination with immune checkpoint blockade is a powerful strategy to enhance antitumor immunotherapy without concerns of systemic toxicity.

Advanced Magnetic Resonance Imaging in Pediatric Glioblastomas

The shortly upcoming 5th edition of the World Health Organization Classification of Tumors of the Central Nervous System is bringing extensive changes in the terminology of diffuse high-grade gliomas (DHGGs). Previously "glioblastoma," as a descriptive entity, could have been applied to classify some tumors from the family of pediatric or adult DHGGs. However, now the term "glioblastoma" has been divested and is no longer applied to tumors in the family of pediatric types of DHGGs. As an entity, glioblastoma remains, however, in the family of adult types of diffuse gliomas under the insignia of "glioblastoma, IDH-wildtype." Of note, glioblastomas still can be detected in children when glioblastoma, IDH-wildtype is found in this population, despite being much more common in adults. Despite the separation from the family of pediatric types of DHGGs, what was previously labeled as "pediatric glioblastomas" still remains with novel labels and as new entities. As a result of advances in molecular biology, most of the previously called "pediatric glioblastomas" are now classified in one of the four family members of pediatric types of DHGGs. In this review, the term glioblastoma is still apocryphally employed mainly due to its historical relevance and the paucity of recent literature dealing with the recently described new entities. Therefore, "glioblastoma" is used here as an umbrella term in the attempt to encompass multiple entities such as astrocytoma, IDH-mutant (grade 4); glioblastoma, IDH-wildtype; diffuse hemispheric glioma, H3 G34-mutant; diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype; and high grade infant-type hemispheric glioma. Glioblastomas are highly aggressive neoplasms. They may arise anywhere in the developing central nervous system, including the spinal cord. Signs and symptoms are non-specific, typically of short duration, and usually derived from increased intracranial pressure or seizure. Localized symptoms may also occur. The standard of care of "pediatric glioblastomas" is not well-established, typically composed of surgery with maximal safe tumor resection. Subsequent chemoradiation is recommended if the patient is older than 3 years. If younger than 3 years, surgery is followed by chemotherapy. In general, "pediatric glioblastomas" also have a poor prognosis despite surgery and adjuvant therapy. Magnetic resonance imaging (MRI) is the imaging modality of choice for the evaluation of glioblastomas. In addition to the typical conventional MRI features, i.e., highly heterogeneous invasive masses with indistinct borders, mass effect on surrounding structures, and a variable degree of enhancement, the lesions may show restricted diffusion in the solid components, hemorrhage, and increased perfusion, reflecting increased vascularity and angiogenesis. In addition, magnetic resonance spectroscopy has proven helpful in pre- and postsurgical evaluation. Lastly, we will refer to new MRI techniques, which have already been applied in evaluating adult glioblastomas, with promising results, yet not widely utilized in children.

Nanotechnology-based immunotherapies to combat cancer metastasis

Emerging concepts in nanotechnology have gained particular attention for their clinical translation of immunotherapies of cancer, autoimmune and infectious diseases. Several nanoconstructs have been engineered with unique structural, physicochemical, and functional features as robust alternatives for conventional chemotherapies. Traditional cancer therapies like chemotherapy, radiotherapy, and ultimately surgery are the most widely practiced in biomedical settings. Biomaterials and nanotechnology have introduced vehicles for drug delivery and have revolutionized the concept of the modern immunotherapeutic paradigm. Various types of nanomaterials, such as nanoparticles and, more specifically, drug-loaded nanoparticles are becoming famous for drug delivery applications because of safety, patient compliance, and smart action. Such therapeutic modalities have acknowledged regulatory endorsement and are being used in twenty-first-century clinical settings. Considering the emerging concepts and landscaping potentialities, herein, we spotlight and discuss nanoparticle-based immunotherapies as a smart and sophisticated drug delivery approach to combat cancer metastasis. The introductory part of this manuscript discusses a broad overview of cancer immunotherapy to understand better the tumor microenvironment and nanotechnology-oriented immunomodulatory strategies to cope with advanced-stage cancers. Following that, most addressable problems allied with conventional immunotherapies are given in comparison to nanoparticle-based immunotherapies. The later half of this work comprehensively highlights the requisite delivery of various bioactive entities with particular cases and examples. Finally, this review also encompasses a comprehensive concluding overview and future standpoints to strengthen a successful clinical translation of nanoparticle-based immunotherapies as a smart and sophisticated drug delivery approach.

CD47-SIRPα Checkpoint Inhibition Enhances Neutrophil-Mediated Killing of Dinutuximab-Opsonized Neuroblastoma Cells

Simple Summary

Current immunotherapy for high-risk neuroblastoma patients involves treatment with anti-GD2 antibody dinutuximab, which has significantly improved the survival rate. Still, approximately half of the patients succumb to the tumor; therefore, efforts to improve their prognosis are urgently needed. Since T cell targeting immune checkpoint inhibitors in neuroblastoma are limited due to the low immunogenicity of these tumors, alternative immunotherapeutic approaches should be studied. The therapeutic targeting of the innate immune checkpoint CD47-SIRPα has the ability to enhance antitumor effects of myeloid cells, especially in the presence of cancer-opsonizing antibodies. Given that neutrophil ADCC is a dominant effector mechanism leading to the eradication of dinutuximab-opsonized neuroblastoma cells, we have investigated the therapeutic potential of anti-GD2 antibody in combination with CD47-SIRPα inhibition. We demonstrate here that the capacity of neutrophils to kill dinutuximab-opsonized neuroblastoma cells is controlled by the CD47-SIRPα axis and its disruption promotes their cytotoxic potential even further, significantly improving dinutuximab responsiveness.

Abstract

High-risk neuroblastoma, especially after recurrence, still has a very low survival rate. Immune checkpoint inhibitors targeting T cells have shown remarkable clinical efficacy in adult solid tumors, but their effects in pediatric cancers have been limited so far. On the other hand, targeting myeloid immune checkpoints, such as CD47-SIPRα, provide the opportunity to enhance antitumor effects of myeloid cells, including that of neutrophils, especially in the presence of cancer-opsonizing antibodies. Disialoganglioside (GD2)-expressing neuroblastoma cells targeted with anti-GD2 antibody dinutuximab are in part eradicated by neutrophils, as they recognize and bind the antibody targeted tumor cells through their Fc receptors. Therapeutic targeting of the innate immune checkpoint CD47-SIRPα has been shown to promote the potential of neutrophils as cytotoxic cells in different solid tumor indications using different cancer-targeting antibodies. Here, we demonstrate that the capacity of neutrophils to kill dinutuximab-opsonized neuroblastoma cells is also controlled by the CD47-SIRPα axis and can be further enhanced by antagonizing CD47-SIRPα interactions. In particular, CD47-SIRPa checkpoint inhibition enhanced neutrophil-mediated ADCC of dinutuximab-opsonized adrenergic neuroblastoma cells, whereas mesenchymal neuroblastoma cells may evade immune recognition by a reduction of GD2 expression. These findings provide a rational basis for targeting CD47-SIRPα interactions to potentiate dinutuximab responsiveness in neuroblastomas with adrenergic phenotype.

Immunogenomic determinants of tumor microenvironment correlate with superior survival in high-risk neuroblastoma

BACKGROUND

Tumor-infiltrating CD8⁺ T cells and neoantigens are predictors of a favorable prognosis and response to immunotherapy with checkpoint inhibitors in many types of adult cancer, but little is known about their role in pediatric malignancies. Here, we analyzed the prognostic strength of T cell-inflamed gene expression and neoantigen load in high-risk neuroblastoma. We also compared transcriptional programs in T cell-inflamed and non-T cell-inflamed high-risk neuroblastomas to investigate possible mechanisms of immune exclusion.

METHODS

A defined T cell-inflamed gene expression signature was used to categorize high-risk neuroblastomas in the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) program (n=123), and the Gabriella Miller Kids First (GMKF) program (n=48) into T cell-inflamed, non-T cell-inflamed, and intermediate groups. Associations between the T cell-inflamed and non-T cell-inflamed group, MYCN amplification, and survival were analyzed by Cox proportional hazards models. Additional survival analysis was conducted after integrating neoantigen load predicted from somatic mutations. Pathways activated in non-T cell-inflamed relative to T cell-inflamed tumors were analyzed using causal network analysis.

RESULTS

Patients with T cell-inflamed high-risk tumors showed improved overall survival compared with those with non-T cell-inflamed tumors (p<0.05), independent of MYCN amplification status, in both TARGET and GMKF cohorts. Higher neoantigen load was also associated with better event-free and overall survival (p<0.005) and was independent of the T cell-inflamed signature. Activation of MYCN, ASCL1, SOX11, and KMT2A transcriptional programs was inversely correlated with the T cell-inflamed signature in both cohorts.

CONCLUSIONS

Our results indicate that tumors from children with high-risk neuroblastoma harboring a strong T cell-inflamed signature have a more favorable clinical outcome, and neoantigen load is a prognosis predictor, independent of T cell inflammation. Strategies to target SOX11 and other signaling pathways associated with non-T cell-inflamed tumors should be pursued as potential immune-potentiating interventions.

Expression of programmed death ligand 1 in drug-resistant osteosarcoma: An exploratory study

Background

Inhibition of the programmed death ligand 1, programmed death 1 pathway has been successfully used for treatment of multiple advanced adult cancers. However, its use in pediatric osteosarcoma is still in its infancy. In this study, we investigated programmed death ligand 1 and other checkpoint molecules' expression to determine the potential usefulness as targets for drug therapy.

Methods

We incubated human wild-type osteosarcoma cells with incremental concentrations of doxorubicin to create a doxorubicin-resistant cell line. Matrigel in vitro invasion assays were used to compare invasiveness. Comparative programmed death ligand 1 expression was evaluated by Western blot assays. An immuno-oncology checkpoint protein panel was used to compare concentrations of 16 other checkpoint molecules. Chi-square tests and Wilcoxon rank-sum tests were used to determine significant differences.

Results

A doxorubicin-resistant cell line was successfully created and was significantly more invasive than wild-type cells (0.47 vs 0.07, P < .001). On Western blot assay, doxorubicin-resistant but not wild-type cells expressed programmed death ligand 1. Doxorubicin-resistant cells had significantly higher levels of T-cell immunoglobulin-3 and cluster of differentiation 86 and higher cluster of differentiation 27, cluster of differentiation 40, lymphocyte-activation gene-3, cluster of differentiation 80, programmed death ligand 1, programmed death ligand 2, and inducible T-cell costimulatory expression than wild-type cells. Both lines expressed B- and T-lymphocyte attenuator, cluster of differentiation 28, herpesvirus entry mediator, and programmed death 1. Herpesvirus entry mediator, cluster of differentiation 40, and programmed death ligand 2 were also present in the culture media of both cell lines.

Conclusion

Doxorubicin-resistant osteosarcoma seems to express higher programmed death ligand 1 than nonresistant wild-type cells. Benchmarking checkpoint molecules may provide the basis for future studies that elucidate pathways of drug resistance and tumor metastasis, biomarkers for cancer prognosis or recurrence, and future targets for directed drug therapy.

Synthetic bacterial vesicles combined with tumour extracellular vesicles as cancer immunotherapy

Bacterial outer membrane vesicles (OMV) have gained attention as a promising new cancer vaccine platform for efficiently provoking immune responses. However, OMV induce severe toxicity by activating the innate immune system. In this study, we applied a simple isolation approach to produce artificial OMV that we have named Synthetic Bacterial Vesicles (SyBV) that do not induce a severe toxic response. We also explored the potential of SyBV as an immunotherapy combined with tumour extracellular vesicles to induce anti-tumour immunity. Bacterial SyBV were produced with high yield by a protocol including lysozyme and high pH treatment, resulting in pure vesicles with very few cytosolic components and no RNA or DNA. These SyBV did not cause systemic pro-inflammatory cytokine responses in mice compared to naturally released OMV. However, SyBV and OMV were similarly effective in activation of mouse bone marrow-derived dendritic cells. Co-immunization with SyBV and melanoma extracellular vesicles elicited tumour regression in melanoma-bearing mice through Th-1 type T cell immunity and balanced antibody production. Also, the immunotherapeutic effect of SyBV was synergistically enhanced by anti-PD-1 inhibitor. Moreover, SyBV displayed significantly greater adjuvant activity than other classical adjuvants. Taken together, these results demonstrate a safe and efficient strategy for eliciting specific anti-tumour responses using immunotherapeutic bacterial SyBV.

Novel immunomodulatory properties of low dose cytarabine entrapped in a mannosylated cationic liposome

Cancer treatment remains unsatisfactory with high rates of recurrence and metastasis. Immunomodulatory agents capable of promoting cellular antitumor immunity while inhibiting the local immunosuppressive tumor microenvironment could greatly improve cancer treatment. We have developed a multi-targeted mannosylated cationic liposome delivery system containing muramyl dipeptide (DS) and low doses of the chemotherapeutic agent cytarabine (Ara-C). Immunomodulation of primary immune cells and immortalized cancer cell lines by Ara-C/DS was assessed by measuring cytokine levels and surface marker expression. As a proof of concept, the generation of targeted cellular immunity was investigated in the context of responses to viral antigens. This report is the first demonstrating that Ara-C combined with DS can modulate immune responses and revert immunosuppression as evidenced by increased IFN-γ and IL-12p40 without changes in IL-10 in peripheral blood mononuclear cells, and increased CD80 and decreased CD163 on immunosuppressive macrophages. Furthermore, Ara-C/DS increased MHC class I expression on cancer cells while increasing the production of antigen-specific IFN-γ⁺ CD8⁺ T cells in viral peptide-challenged lymphocytes from both humans and vaccinated mice. Taken together, these results are the first to document immunomodulatory properties of Ara-C linked with recognition of antigens and potentially the generation of antitumor immune memory.

Immune-checkpoint blockade of CTLA-4 (CD152) in antigen-specific human T-cell responses differs profoundly between neonates, children, and adults

The monoclonal antibody against CTLA-4, Ipilimumab, is a first-in-class immune-checkpoint inhibitor approved for treatment of advanced melanoma in adults but not extensively studied in children. In light of the fact that the immune response early in life differs from that of adults, we have applied a human in vitro model stimulating CD4⁺ T-cells from neonates, children (1–5 years), and adults antigen-specifically with Staphylococcus aureus (S. aureus) for assessment of CTLA-4 blockade early in life. We show that T-cell proliferation as well as frequencies of antigen-specific T-cells (CD40L⁺CD4⁺) were enhanced in neonatal T-cells upon CTLA-4 blockade showing a larger variance within the group (F-test p < .0001). Using machine learning algorithm Random Forest, adult and neonatal T-cell responses can be unambiguously categorized (F1 score-0.75) on the basis of their cytokine (co-)expression. Blockade of CTLA-4 enhanced frequencies of IL-8, IFNγ, and IL-10 producers among CD40L⁺ T-cells. Of note, antigen-specific T-cells from neonates displayed higher cytokine coproduction at baseline, while T-cells from children caught up to neonates, and adults to baseline of children upon CTLA-4 blockade. These findings reveal that in neonatal T-cells blockade of CTLA-4 mainly unleashes the antigen-specific capacity by increasing the numbers of responding T-cells, whereas in children and adults it promotes the coexpression of cytokines by individual T-cells. Thus, CTLA-4 blockade boosts antitumor immunity through different mechanisms depending on the patients’ age. These data implicate a strong impact of the developmental stage of the T-cell compartment on the effects of immune-checkpoint therapy.

Reversing T-cell exhaustion in immunotherapy: a review on current approaches and limitations

Introduction:T cell functions are altered during chronic viral infections and tumor development. This is mainly manifested by significant changes in T cells' epigenetic and metabolic landscapes, pushing them into an 'exhausted' state. Reversing this T cell exhaustion has been emerging as a 'game-changing' therapeutic approach against cancer and chronic viral infection.Areas covered:This review discusses the cellular pathways related to T cell exhaustion, and the clinical development and possible cellular targets that can be exploited therapeutically to reverse this exhaustion. We searched various databases (e.g. Google Scholar, PubMed, Elsevier, and other scientific database sites) using the keywords T cell exhaustion, T cell activation, co-inhibitory receptors, and reversing T cell exhaustion.Expert opinion:The discovery of the immune checkpoints pathways represents a significant milestone toward understanding and reversing T cell exhaustion. Antibodies that target these pathways have already demonstrated promising activities in reversing T cell exhaustion. Nevertheless, there are still many associated limitations. In this context, next-generation alternatives are on the horizon. This includes the use of small molecules to block the immune checkpoints' receptors, combining them with other treatments, and identifying novel, safer and more effective immunotherapeutic targets.

Precision medicine in pediatric solid cancers

Despite huge advances in the diagnosis and treatment of pediatric cancers over the past several decades, it remains one of the leading causes of death during childhood in developed countries. The development of new targeted treatments for these diseases has been hampered by two major factors. First, the extremely heterogeneous nature of the types of tumors encountered in this age group, and their fundamental differences from common adult carcinomas, has made it hard to truly get a handle on the complexities of the underlying biology driving tumor growth. Second, a reluctance of the pharmaceutical industry to develop products or trials for this population due to the relatively small size of the 'market', and a too-easy mechanism of obtaining waivers for pediatric development of adult oncology drugs based on disease type rather than mechanism of action, led to significant difficulties in getting access to new drugs. Thankfully, the field has now started to change, both scientifically and from a regulatory perspective, in order to address some of these challenges. In this review, we will examine some of the recent insights into molecular features which make pediatric tumors so unique and how these might represent therapeutic targets; highlight ongoing international initiatives for providing comprehensive, personalized genomic profiling of childhood tumors in a clinically-relevant timeframe, and look briefly at where the field of pediatric precision oncology may be heading in future.

Safety and Efficacy of Immune Checkpoint Inhibitors in Children and Young Adults with Haematological Malignancies: Review and Future Perspectives

Despite the marked improvement in overall survival rates of paediatric patients with haematological malignancies that has been achieved during the last decades, there is still a pressing need for novel therapeutic approaches for the subset of patients with relapsed or refractory disease. Immune checkpoint inhibitors aim to induce potent anti-tumour immune responses by targeted blockade of inhibitory receptors and have shown great promise in preclinical models and studies in the adult population. However, paediatric malignancies present unique features and so far, experience with these agents remains limited. In the current review we present an overview of efficacy and safety data from case reports, case series and clinical trials employing the use of immune checkpoint inhibitors in children, adolescents and young adults with haematological malignancies. We also discuss new possibilities involving novel targets and combination treatments and provide a summary of the currently registered clinical trials.

Overexpression of Endogenous Retroviruses and Malignancy Markers in Neuroblastoma Cell Lines by Medium-Induced Microenvironmental Changes

Neuroblastoma (NB) is the commonest solid tumor outside the central nervous system in infancy and childhood with a unique biological heterogeneity. In patients with advanced, metastasizing neuroblastoma, treatment failure and poor prognosis is often marked by resistance to chemo- or immunotherapy. Thus, identification of robust biomarkers seems essential for understanding tumor progression and developing effective therapy. Here, we have studied the expression of human endogenous retroviruses (HERV) as potential targets in NB cell lines during stem-cell medium-induced microenvironmental change. Quantitative PCR revealed that relative expression of the HERV-K family and HERV-W1 ENV were increased in all three NB cell lines after incubation in stem-cell medium. Virus transcriptome analyses revealed the transcriptional activation of three endogenous retrovirus elements: HERV-R ENV (ERV3-1), HERV-E1 and HERV-Fc2 ENV (ERVFC1-1). Known malignancy markers in NB, e.g. proto-oncogenic MYC or MYCN were expressed highly heterogeneously in the three investigated NB cell lines with up-regulation of MYC and MYCN upon medium-induced microenvironmental change. In addition, SiMa cells exclusively showed a phenotype switching from loosely-adherent monolayers to low proliferating grape-like cellular aggregates, which was accompanied by an enhanced CD133 expression. Interestingly, the overexpression of HERV was associated with a significant elevation of immune checkpoint molecule CD200 in both quantitative PCR and RNA-seq analysis suggesting tumor escape mechanism in NB cell lines after incubation in serum-free stem cell medium.

Radiation therapy and molecular-targeted agents in preclinical testing for immunotherapy, brain tumors, and sarcomas: Opportunities and challenges

Despite radiation therapy (RT) being an integral part of the treatment of most pediatric cancers and the recent discovery of novel molecular-targeted agents (MTAs) in this era of precision medicine with the potential to improve the therapeutic ratio of modern chemoradiotherapy regimens, there are only a few preclinical trials being conducted to discover novel radiosensitizers and radioprotectors. This has resulted in a paucity of translational clinical trials combining RT and novel MTAs. This report describes the opportunities and challenges of investigating RT together with MTAs in preclinical testing for immunotherapy, brain tumors, and sarcomas in pediatric oncology. We discuss the need for improving the collaboration between radiation oncologists, biologists, and physicists to improve the reliability, reproducibility, and translational potential of RT-based preclinical research. Current translational clinical trials using RT and MTAs for immunotherapy, brain tumors, and sarcomas are described. The technologic advances in experimental RT, availability of novel experimental tumor models, advances in immunology and tumor biology, and the discovery of novel MTAs together hold considerable promise for good quality preclinical and clinical multimodality research to improve the current rates of survival and toxicity in children afflicted with cancer.

Epigenomics and immunotherapeutic advances in pediatric brain tumors

Brain tumors are the leading cause of childhood cancer-related deaths. Similar to adult brain tumors, pediatric brain tumors are classified based on histopathological evaluations. However, pediatric brain tumors are often histologically inconsistent with adult brain tumors. Recent research findings from molecular genetic analyses have revealed molecular and genetic changes in pediatric tumors that are necessary for appropriate classification to avoid misdiagnosis, the development of treatment modalities, and the clinical management of tumors. As many of the molecular-based therapies developed from clinical trials on adults are not always effective against pediatric brain tumors, recent advances have improved our understanding of the molecular profiles of pediatric brain tumors and have led to novel epigenetic and immunotherapeutic treatment approaches currently being evaluated in clinical trials. In this review, we focus on primary malignant brain tumors in children and genetic, epigenetic, and molecular characteristics that differentiate them from brain tumors in adults. The comparison of pediatric and adult brain tumors highlights the need for treatments designed specifically for pediatric brain tumors. We also discuss the advancements in novel molecularly targeted drugs and how they are being integrated with standard therapy to improve the classification and outcomes of pediatric brain tumors in the future.

Beyond Tumor Mutation Burden: Tumor Neoantigen Burden as a Biomarker for Immunotherapy and Other Types of Therapy

Immunotherapy has significantly improved the clinical outcome of patients with cancer. However, the immune response rate varies greatly, possibly due to lack of effective biomarkers that can be used to distinguish responders from non-responders. Recently, clinical studies have associated high tumor neoantigen burden (TNB) with improved outcomes in patients treated with immunotherapy. Therefore, TNB has emerged as a biomarker for immunotherapy and other types of therapy. In the present review, the potential application of TNB as a biomarker was evaluated. The methods of neoantigen prediction were summarized and the mechanisms involved in TNB were investigated. The impact of high TNB and increased number of infiltrating immune cells on the efficacy of immunotherapy was also addressed. Finally, the future challenges of TNB were discussed.

Immune Checkpoints in Pediatric Solid Tumors: Targetable Pathways for Advanced Therapeutic Purposes

The tumor microenvironment (TME) represents a complex network between tumor cells and a variety of components including immune, stromal and vascular endothelial cells as well as the extracellular matrix. A wide panel of signals and interactions here take place, resulting in a bi-directional modulation of cellular functions. Many stimuli, on one hand, induce tumor growth and the spread of metastatic cells and, on the other hand, contribute to the establishment of an immunosuppressive environment. The latter feature is achieved by soothing immune effector cells, mainly cytotoxic T lymphocytes and B and NK cells, and/or through expansion of regulatory cell populations, including regulatory T and B cells, tumor-associated macrophages and myeloid-derived suppressor cells. In this context, immune checkpoints (IC) are key players in the control of T cell activation and anti-cancer activities, leading to the inhibition of tumor cell lysis and of pro-inflammatory cytokine production. Thus, these pathways represent promising targets for the development of effective and innovative therapies both in adults and children. Here, we address the role of different cell populations homing the TME and of well-known and recently characterized IC in the context of pediatric solid tumors. We also discuss preclinical and clinical data available using IC inhibitors alone, in combination with each other or administered with standard therapies.

Robust Prediction of Immune Checkpoint Inhibition Therapy for Non-Small Cell Lung Cancer

Background

The development of immune checkpoint inhibitors (ICIs) is a revolutionary milestone in the field of immune-oncology. However, the low response rate is the major problem of ICI treatment. The recent studies showed that response rate to single-agent programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) inhibition in unselected non-small cell lung cancer (NSCLC) patients is 25% so that researchers defined several biomarkers to predict the response of immunotherapy in ICIs treatment. Common biomarkers like tumor mutational burden (TMB) and PD-L1 expression have several limitations, such as low accuracy and inadequately validated cutoff value.

Methods

Two published and an unpublished ICIs treatment NSCLC cohorts with 129 patients were collected and divided into a training cohort (n = 53), a validation cohort (n = 22), and two independent test cohorts (n = 34 and n = 20). We identified six immune-related pathways whose mutational status was significantly associated with overall survival after ICIs treatment. Then these pathways mutational status combined with TMB, PD-L1 expression and intratumor heterogeneity were incorporated to build a Bayesian-regularization neural networks (BRNN) model to predict the ICIs treatment response.

Results

We firstly proved that TMB, PD-L1, and mutant-allele tumor heterogeneity (MATH) were independent biomarkers. The survival analysis of six immune-related pathways revealed the mutational status could distinguish overall survival after ICIs treatment. When predicting immunotherapy efficacy, the overall accuracy of area under curve (AUC) in validation cohort reaches 0.85, outperforming previous predictors in either sensitivity or specificity. And the AUC in two independent test cohorts reach 0.74 and 0.80.

Conclusion

We developed a pathway-model that could predict the efficacy of ICIs in NSCLC patients. Our study made a significant contribution to solving the low prediction accuracy of immunotherapy of single biomarker. With the accumulation of larger data sets, further studies are warranted to refine the predictive performance of the approach.

A novel multimeric IL15/IL15Rα-Fc complex to enhance cancer immunotherapy

The role of T cells in controlling human cancers is well known. Their success requires continued persistence in vivo and efficient trafficking to tumor sites, requirements shared by other effectors such as Natural Killer (NK) cells. To date, cytokine IL2 remains the only clinically approved cytokine therapy available to expand, maintain, and activate these effector lymphoid cells, but toxicities can be severe. Cytokine IL15 offers similar T cell proliferation and activation properties, but without the unwanted side-effects seen with IL2. Several IL15-cytokine fusion proteins have been developed to improve their in vivo function, typically exploiting the IL15Rα to complex with IL15, to extend serum half-life and increase affinity for IL15β receptor on immune cells. Here we describe a novel IL15 complex incorporating the full-length IL15Rα to complex with wild type IL15 to form spontaneous trimers of dimers (6 IL15 + 6 IL15Rα) during co-expression, resulting in a substantial increase in serum half-life and enhancement of in vivo cytokine effect on IgG or T cell engaging antibody-dependent cell-mediated cytotoxicities, when compared to alternative strategies.

Identification of prognostic immune-related genes in rhabdoid tumor of kidney based on TARGET database analysis

Background: Malignant rhabdoid tumor of the kidney (RTK) is a rare and highly aggressive pediatric malignancy. Immune system dysfunction is significantly correlated with tumor initiation and progression.

Methods: We integrated and analyzed the expression profiles of immune-related genes (IRGs) in 65 RTK patients based on the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database. Prognostic related IRGs in RTK patients were analyzed using univariate and multivariate analysis, based on which a prognostic model with IRGs was constructed. Correlation analysis between the risk score of our model and tumor-infiltrating cell were also investigated.

Results: Twenty two IRGs were significantly associated with the clinical outcomes of RTK patients. Gene ontology (GO) analysis revealed that inflammatory pathways were most frequently implicated in RTK. A prognostic model was constructed using 7 IRGs (MMP9, SERPINA3, FAM19A5, CCR9, PLAUR, IL1R2, PRKCG), which were independent prognostic indices that could differentiate patients based on their survival outcomes. Furthermore, the risk scores from our prognostic model was positively associated with cancer-associated fibroblasts (CAFs).

Conclusions: We screened seven IRGs of clinical significance to distinguish patients with different survival outcomes. This may enhance our understanding of the immune microenvironment of RTK, and could use to design individualized treatments for RTK patients.

Background: Malignant rhabdoid tumor of the kidney (RTK) is a rare and highly aggressive pediatric malignancy. Immune system dysfunction is significantly correlated with tumor initiation and progression.

Methods: We integrated and analyzed the expression profiles of immune-related genes (IRGs) in 65 RTK patients based on the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database. Prognostic related IRGs in RTK patients were analyzed using univariate and multivariate analysis, based on which a prognostic model with IRGs was constructed. Correlation analysis between the risk score of our model and tumor-infiltrating cell were also investigated.

Results: Twenty two IRGs were significantly associated with the clinical outcomes of RTK patients. Gene ontology (GO) analysis revealed that inflammatory pathways were most frequently implicated in RTK. A prognostic model was constructed using 7 IRGs (MMP9, SERPINA3, FAM19A5, CCR9, PLAUR, IL1R2, PRKCG), which were independent prognostic indices that could differentiate patients based on their survival outcomes. Furthermore, the risk scores from our prognostic model was positively associated with cancer-associated fibroblasts (CAFs).

Conclusions: We screened seven IRGs of clinical significance to distinguish patients with different survival outcomes. This may enhance our understanding of the immune microenvironment of RTK and could use to design individualized treatments for RTK patients.

Cutaneous reactions to pediatric cancer treatment part II: Targeted therapy

Cancer remains a leading cause of morbidity and mortality among children. Targeted therapies may improve survivorship; however, unique side-effect profiles have also emerged with these novel therapies. Changes in hair, skin, and nails-termed dermatologic adverse events (AEs)-are among the most common sequelae and may result in interruption or discontinuation of therapy. Though dermatologic AEs have been detailed in adults, these findings are not well described in the pediatric population. We reviewed the literature to characterize dermatologic AEs to anticancer targeted therapies available as of July 2020 and summarized the spectrum of clinical findings as well as treatment recommendations for children. Dermatologic AEs are among the most common AEs reported in pediatric patients receiving targeted therapy, but morphologic and histologic descriptions are often lacking in current publications. Pediatric dermatologists are uniquely poised to recognize specific morphology of dermatologic AEs and make recommendations for prevention and treatment that may improve quality of life and enable ongoing cancer therapy.

Tumor-Specific Antibody, Cetuximab, Enhances the In Situ Vaccine Effect of Radiation in Immunologically Cold Head and Neck Squamous Cell Carcinoma

In head and neck squamous cell carcinoma (HNSCC) tumors that over-expresses huEGFR, the anti-EGFR antibody, cetuximab, antagonizes tumor cell viability and sensitizes to radiation therapy. However, the immunologic interactions between cetuximab and radiation therapy are not well understood. We transduced two syngeneic murine HNSCC tumor cell lines to express human EGFR (MOC1- and MOC2-huEGFR) in order to facilitate evaluation of the immunologic interactions between radiation and cetuximab. Cetuximab was capable of inducing antibody-dependent cellular cytotoxicity (ADCC) in MOC1- and MOC2-huEGFR cells but showed no effect on the viability or radiosensitivity of these tumor cells, which also express muEGFR that is not targeted by cetuximab. Radiation enhanced the susceptibility of MOC1- and MOC2-huEGFR to ADCC, eliciting a type I interferon response and increasing expression of NKG2D ligands on these tumor cells. Co-culture of splenocytes with cetuximab and MOC2-huEGFR cells resulted in increased expression of IFNγ in not only NK cells but also in CD8+ T cells, and this was dependent upon splenocyte expression of FcγR. In MOC2-huEGFR tumors, combining radiation and cetuximab induced tumor growth delay that required NK cells, EGFR expression, and FcγR on host immune cells. Combination of radiation and cetuximab increased tumor infiltration with NK and CD8+ T cells but not regulatory T cells. Expression of PD-L1 was increased in MOC2-huEGFR tumors following treatment with radiation and cetuximab. Delivering anti-PD-L1 antibody with radiation and cetuximab improved survival and resulted in durable tumor regression in some mice. Notably, these cured mice showed evidence of an adaptive memory response that was not specifically directed against huEGFR. These findings suggest an opportunity to improve the treatment of HNSCC by combining radiation and cetuximab to engage an innate anti-tumor immune response that may prime an effective adaptive immune response when combined with immune checkpoint blockade. It is possible that this approach could be extended to any immunologically cold tumor that does not respond to immune checkpoint blockade alone and for which a tumor-specific antibody exists or could be developed.

Immune profiling of pediatric solid tumors

Pediatric cancers, particularly high-risk solid tumors, urgently need effective and specific therapies. Their outlook has not appreciably improved in decades. Immunotherapies such as immune checkpoint inhibitors offer much promise, but most are only approved for use in adults. Though several hundred clinical trials have tested immune-based approaches in childhood cancers, few have been guided by biomarkers or clinical-grade assays developed to predict patient response and, ultimately, to help select those most likely to benefit. There is extensive evidence in adults to show that immune profiling has substantial predictive value, but few studies focus on childhood tumors, because of the relatively small disease population and restricted use of immune-based therapies. For instance, only one published study has retrospectively examined the immune profiles of pediatric brain tumors after immunotherapy. Furthermore, application and integration of advanced multiplex techniques has been extremely limited. Here, we review the current status of immune profiling of pediatric solid tumors, with emphasis on tumor types that represent enormous unmet clinical need, primarily in the context of immune checkpoint inhibitor therapy. Translating optimized and informative immune profiling into standard practice and access to personalized combination therapy will be critical if childhood cancers are to be treated effectively and affordably.

CD200 is overexpressed in neuroblastoma and regulates tumor immune microenvironment

Patients with pediatric cancers such as neuroblastoma (NB) are often unresponsive to checkpoint blockade immunotherapy. One major factor in pediatric tumor resistance to immunotherapy is considered to be the low mutation rate of pediatric tumors. Another factor may be the overexpression of additional inhibitory pathways. While analyzing the RNA-sequencing database TARGET, we found that human NB tumors overexpress immune checkpoint molecule CD200. To determine its significance and impact on tumor immune microenvironment, we analyzed 49 cases of previously untreated, surgically removed NB tumors using immunohistochemistry and multi-color flow cytometry (FACS). We found that CD200 is overexpressed in more than 90% of NB tumors. In the tumor microenvironment of NB, CD200 is mainly overexpressed in CD45^- NB tumor cells, while its cognate receptor (CD200R) is mainly expressed in HLA-DR⁺CD14⁺ myeloid cells and CD11c⁺ dendritic cells. Low-level expression of CD200R is also observed in tumor-infiltrating CD4⁺ and CD8⁺ T cells. In NB tumors with higher CD200 expression (CD200^high), we observed lower numbers of HLA-DR⁺CD14⁺ myeloid cells and less tumor-infiltrating CD4⁺ and CD8⁺ T cells. Moreover, we found that CD4⁺ and CD8⁺ T cells produced less IFN-γ and/or TNF-α in CD200^high NB tumors. Thus, CD200-CD200R pathway appears to downregulate anti-tumor immunity in the tumor microenvironment of NB tumors, and blockade of this pathway may be beneficial for NB patients.

Mini-Review on Targeted Treatment of Desmoplastic Small Round Cell Tumor

Desmoplastic small round cell tumor (DSRCT) is a devastating disease which most commonly affects adolescents, with a male predominance. Despite the best multimodality treatment efforts, most patients will ultimately not survive more than 3-5 years after diagnosis. Some research trials in soft-tissue sarcoma and Ewing sarcoma include DSRCT patients but few studies have been tailored to the specific clinical needs and underlying cytogenetic abnormalities characterizing this disease such as the typical EWSR1-WT1 gene fusion. Downstream activation of EWSR1-WT1 gene fusion includes signaling pathways of platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and insulin growth factor (IGF)-1. Other biological pathways that are activated and expressed in DSRCT cells include endothelial growth factor receptor (EGFR), androgen receptor pathway, c-KIT, MET, and transforming growth factor (TGF) beta. Investigation of somatic mutations, copy number alterations (CNA), and chromosomes in DSRCT samples suggests that deregulation of mesenchymal-epithelial reverse transition (MErT)/epithelial-mesenchymal transition (EMT) and DNA damage repair (DDR) may be important in DSRCT. This mini review looks at known druggable targets in DSRCT and existing clinical evidence for targeted treatments, particularly multityrosine kinase inhibitors such as pazopanib, imatinib, and sorafenib alone or in combination with other agents such as mTOR (mammalian target of rapamycin) inhibitors. The aim is to increase shared knowledge about current available treatments and identify gaps in research to further efforts toward clinical development of targeted agents.

Comprehensive Survey of Clinical Trials Registration for Melanoma Immunotherapy in the ClinicalTrials.gov

Objective: Comprehensively evaluate the immunotherapeutic clinical trials and provide reference for melanoma treatment and research.

Methods: The website of ClinicalTrials.gov was searched to retrieve and download all registered clinical trials for melanoma immunotherapy on August 1 (updated on August 25), 2019. All registration trials met the inclusion criteria were collected regardless of the type of study, the status of recruitment, and the results of the study. The general characteristics, methodological characteristics, and the types of immunotherapeutic drugs included of these trials were analyzed.

Results: Finally, 242 eligible trials were included and evaluated. Of them, 30.6% were completed, 16.9% were terminated, and two were withdrawn; 77.7% recruited less than 100 participants; 30.5% were randomized; 45.5% was single group assignment; 88.8% were not masked; the primary purpose was treatment; 44.2% had data on monitoring committees; 27.7% used US FDA-regulated immunization drugs; 78.5% without results posted; 43.0% were sponsored by the industry. Immunological checkpoint inhibitors were most often studied, with 53.6% of the trials involving PD-1, the most commonly studied was Nivolumab.

Conclusions: Currently, most of the registered clinical trials for melanoma immunotherapy were interventional open-label trials. Most immunotherapy research hotspots were in the FDA-regulated drug product, and a few trials reported available test results. It is necessary to strengthen the supervision of results and explore and disseminate more effective and safe immunotherapy methods.

Thyroid Sequelae of Pediatric Cancer Therapy

The hypothalamic-pituitary-thyroid axis is a common site of unintended, acquired disease either during or after the treatment of cancer. Children treated with external radiation therapy are at the highest risk for developing a thyroid-related late effect, but thyroid dysfunction and second primary thyroid neoplasms can also occur after treatment with radiopharmaceutical agents such as 131I-metaiodobenzylguanidine. Increasingly recognized is the development of early thyroid dysfunction as an off-target consequence of the more novel cancer therapeutics such as the tyrosine kinase inhibitors and immune checkpoint inhibitors. Thyroid sequelae resulting from irradiation may manifest only after years to decades of follow-up, and their resultant clinical symptoms may be indolent and non-specific. Therefore, lifelong monitoring of the childhood cancer survivor at risk for thyroid disease is paramount. In this comprehensive review, the myriad thyroid adverse effects resulting from pediatric cancer treatment are discussed and an overview of screening and treatment of these thyroid sequelae provided.