Molecular Pathways: Targeting B7-H3 (CD276) for Human Cancer Immunotherapy

Past, Current, and Future of Immunotherapies for Prostate Cancer

Prostate cancer (PCa) is the most common cancer in men, and the second leading cause of cancer related death in men in Western countries. The standard therapy for metastatic PCa is androgen suppression therapy (AST). Men undergoing AST eventually develop metastatic castration-resistant prostate cancer (mCRPC), of which there are limited treatment options available. Immunotherapy has presented substantial benefits for many types of cancer, but only a marginal benefit for mCRPC, at least in part, due to the immunosuppressive tumor microenvironment (TME). Current clinical trials are investigating monotherapies or combination therapies involving adoptive cellular therapy, viral, DNA vaccines, oncolytic viruses, and immune checkpoint inhibitors (ICI). Immunotherapies are also being combined with chemotherapy, radiation, and AST. Additionally, preclinical investigations show promise with the recent description of alternative ways to circumvent the immunosuppressive nature of the prostate tumor microenvironment, including harnessing the immune stimulatory NKG2D pathway, inhibiting myeloid derived suppressor cells, and utilizing immunomodulatory oncolytic viruses. Herein we provide an overview of recent preclinical and clinical developments in cancer immunotherapies and discuss the perspectives for future immunotherapies in PCa.

B7-H3-redirected chimeric antigen receptor T cells target glioblastoma and neurospheres

BACKGROUND

The dismal survival of glioblastoma (GBM) patients urgently calls for the development of new treatments. Chimeric antigen receptor T (CAR-T) cells are an attractive strategy, but preclinical and clinical studies in GBM have shown that heterogeneous expression of the antigens targeted so far causes tumor escape, highlighting the need for the identification of new targets. We explored if B7-H3 is a valuable target for CAR-T cells in GBM.

METHODS

We compared mRNA expression of antigens in GBM using TCGA data, and validated B7-H3 expression by immunohistochemistry. We then tested the antitumor activity of B7-H3-redirected CAR-T cells against GBM cell lines and patient-derived GBM neurospheres in vitro and in xenograft murine models.

FINDINGS

B7-H3 mRNA and protein are overexpressed in GBM relative to normal brain in all GBM subtypes. Of the 46 specimens analyzed by immunohistochemistry, 76% showed high B7-H3 expression, 22% had detectable, but low B7-H3 expression and 2% were negative, as was normal brain. All 20 patient-derived neurospheres showed ubiquitous B7-H3 expression. B7-H3-redirected CAR-T cells effectively targeted GBM cell lines and neurospheres in vitro and in vivo. No significant differences were found between CD28 and 4-1BB co-stimulation, although CD28-co-stimulated CAR-T cells released more inflammatory cytokines.

INTERPRETATION

We demonstrated that B7-H3 is highly expressed in GBM specimens and neurospheres that contain putative cancer stem cells, and that B7-H3-redirected CAR-T cells can effectively control tumor growth. Therefore, B7-H3 represents a promising target in GBM. FUND: Alex's Lemonade Stand Foundation; Il Fondo di Gio Onlus; National Cancer Institute; Burroughs Wellcome Fund.

T cell cytotoxicity toward hematologic malignancy via B7-H3 targeting

T cells are important effectors in anti-tumor immunity, and aberrant expression of B7 family members may contribute to tumor evasion. In this study, we analyzed expression of costimulatory molecules on human hematologic tumor cells and explored whether B7-H3, a member of the B7 superfamily, is an effective target for T cell mediated cytotoxicity toward hematologic malignancy. We investigated the bispecific antibody anti-CD3 × anti-B7-H3 (B7-H3Bi-Ab) for its ability to redirect T cells to target B7-H3 positive hematologic tumors, including Thp-1, K562, Daudi cells and a primary culture. The capacity of T cells armed with B7-H3Bi-Ab to kill hematologic tumors was evaluated by lactate dehydrogenase assay, flow cytometry, ELISA, and luciferase quantitative assay at an effector/target ratio of 5:1. Compared with unarmed T cells, B7-H3Bi-Ab-armed T cells exhibited significant cytotoxicity toward hematological tumor cells. Moreover, B7-H3Bi-Ab-armed T cells secreted more IFN-γ, TNF-α, IL-2, and Granzyme B and expressed higher levels of activating marker CD69 compared to unarmed T cells. In conclusion, B7-H3Bi-Ab enhances the ability of T cells to kill hematologic tumor cells, and B7-H3 may serve as a novel target for immunotherapy against hematologic malignancy.

High-resolution structural genomics reveals new therapeutic vulnerabilities in glioblastoma

We investigated the role of 3D genome architecture in instructing functional properties of glioblastoma stem cells (GSCs) by generating sub-5-kb resolution 3D genome maps by in situ Hi-C. Contact maps at sub-5-kb resolution allow identification of individual DNA loops, domain organization, and large-scale genome compartmentalization. We observed differences in looping architectures among GSCs from different patients, suggesting that 3D genome architecture is a further layer of inter-patient heterogeneity for glioblastoma. Integration of DNA contact maps with chromatin and transcriptional profiles identified specific mechanisms of gene regulation, including the convergence of multiple super enhancers to individual stemness genes within individual cells. We show that the number of loops contacting a gene correlates with elevated transcription. These results indicate that stemness genes are hubs of interaction between multiple regulatory regions, likely to ensure their sustained expression. Regions of open chromatin common among the GSCs tested were poised for expression of immune-related genes, including CD276. We demonstrate that this gene is co-expressed with stemness genes in GSCs and that CD276 can be targeted with an antibody-drug conjugate to eliminate self-renewing cells. Our results demonstrate that integrated structural genomics data sets can be employed to rationally identify therapeutic vulnerabilities in self-renewing cells.

Translation of cancer immunotherapy from the bench to the bedside

The tremendous success of immune checkpoint blockades has revolutionized cancer management. Our increased understanding of the cell types that compose the tumor microenvironment (TME), including those of the innate and adaptive immune system, has helped to shape additional immune modulatory strategies in cancer care. Pre-clinical and clinical investigations targeting novel checkpoint interactions and key pathways that regulate cancer immunity continue to increase rapidly. Various combinatorial drug regimens are being tested in attempt to achieve durable response and survival rates of patients with cancer. This review provides an overview of specific components of the TME, an introduction to novel immune checkpoints, followed by a survey of present day and future combination immune modulatory therapies. The idea that the immune system can recognize and destroy tumor cells was first described in the cancer immunosurveillance hypothesis of Burnet and Thomas. However, early experimental evidence failed to support the concept. It was not until the late 1990s when seminal papers clearly showed the existence of cancer immunosurveillance, leading to the cancer immunoediting hypothesis. In this century, progress in the understanding of negative regulators of the immune response led to the discovery that inhibition of these regulators in patients with cancer could lead to dramatic and durable remissions. Drs. Tasuku Honjo and James P. Allison were awarded the Nobel Prize in 2018 for their pioneering work in this field. We now see rapid advances in cancer immunology and emerging effective therapies revolutionizing cancer care across tumor types in the clinic, while pre-clinical research is moving from a focus on the malignant cells themselves to dissect the highly heterogenic and complex multi-cellular tumor microenvironment (TME).

Frequent B7-H3 overexpression in craniopharyngioma

Craniopharyngiomas (CPs) are uncommon intracranial benign neoplasms that located in sellar/parasellar region with clinically challenging. B7-H3 is an immune checkpoint molecule highly expressed in many malignant tumors. In this study, we analyzed whether B7-H3 is expressed in 44 CPs samples (adamantinomatous CPs: n = 30 and papillary CPs: n = 14), and whether it could serve as an immunotherapy target in CPs. Immunohistochemical analysis showed that B7-H3 was highly expressed in adamantinomatous CPs (184.3 ± 13.58) and papillary CPs (223.2 ± 11.89), while almost undetectable in normal brain tissue (24 ± 4.9). Besides, B7-H3 expression level was correlated with poor prognosis of patients with CPs. Immunofluorescence and Western blot analysis further suggested that β-catenin co-localized with B7-H3 and could promote its expression in adaCPs. B7-H3 expression level was positively correlated with staining intensity of IBA1⁺ cells, but negatively with T cell infiltration in CPs, suggesting that B7-H3 might play a role in the regulation of tumor microenvironment in CPs. Moreover, B7-H3/CD3 bi-specific T cell engager (BiTE) efficiently inhibited the growth of human primary craniopharyngioma cells in a time- and dose-dependent manner. Our results revealed B7-H3 was highly expressed in CPs and targeting B7-H3 might therefore be an effective therapeutic strategy against craniopharyngioma.

B7-H3 and its role in bone cancers

Most bone cancers have a high risk of metastasis, recurrence, and poor prognosis. Although conventional treatments are still the most important therapy, disadvantages still exist. Therefore, there is an unmet need to develop effective strategies. Immunotherapy is a promising therapy. Immunotherapies targeting checkpoints have proven to be successful, but B7-H3 (CD276, clusters of differentiation protein 276), a member of the B7-family of co-stimulatory molecules, is not being widely studied in bone cancers. This review summarized the studies on B7-H3 in bone cancers. 4 studies investigated B7-H3 expression in osteosarcoma, but there is no study on B7-H3 expression in chondrosarcoma. Two studies investigated the possibility to treat Ewing`s sarcoma through targeting the B7-H3 CAR (chimeric antigen receptors) T-cells or using anti-B7-H3 antibody. A study observed the growth of myeloma in B7-H3-deficient mice and the therapeutic effect of B7-H3 antibody and a study invested B7-H3 expression in myeloma patients. One study reported B7-H3 expression in osteoclastomas and one study investigated B7-H3 expression in chordoma tumor tissues. Two clinical trials are conducting on the therapy of osteosarcoma and myeloma using B7-H3 as a target. In conclusion, B7-H3 could be a target of bone cancers.

CAR T Cells Targeting B7-H3, a Pan-Cancer Antigen, Demonstrate Potent Preclinical Activity Against Pediatric Solid Tumors and Brain Tumors

PURPOSE

Patients with relapsed pediatric solid tumors and CNS malignancies have few therapeutic options and frequently die of their disease. Chimeric antigen receptor (CAR) T cells have shown tremendous success in treating relapsed pediatric acute lymphoblastic leukemia, but this has not yet translated to treating solid tumors. This is partially due to a paucity of differentially expressed cell surface molecules on solid tumors that can be safely targeted. Here, we present B7-H3 (CD276) as a putative target for CAR T-cell therapy of pediatric solid tumors, including those arising in the central nervous system.

EXPERIMENTAL DESIGN

We developed a novel B7-H3 CAR whose binder is derived from a mAb that has been shown to preferentially bind tumor tissues and has been safely used in humans in early-phase clinical trials. We tested B7-H3 CAR T cells in a variety of pediatric cancer models.

RESULTS

B7-H3 CAR T cells mediate significant antitumor activity in vivo, causing regression of established solid tumors in xenograft models including osteosarcoma, medulloblastoma, and Ewing sarcoma. We demonstrate that B7-H3 CAR T-cell efficacy is largely dependent upon high surface target antigen density on tumor tissues and that activity is greatly diminished against target cells that express low levels of antigen, thus providing a possible therapeutic window despite low-level normal tissue expression of B7-H3.

CONCLUSIONS

B7-H3 CAR T cells could represent an exciting therapeutic option for patients with certain lethal relapsed or refractory pediatric malignancies, and should be tested in carefully designed clinical trials.

Combining Immune Checkpoint Inhibitors: Established and Emerging Targets and Strategies to Improve Outcomes in Melanoma

The immune system employs several checkpoint pathways to regulate responses, maintain homeostasis and prevent self-reactivity and autoimmunity. Tumor cells can hijack these protective mechanisms to enable immune escape, cancer survival and proliferation. Blocking antibodies, designed to interfere with checkpoint molecules CTLA-4 and PD-1/PD-L1 and counteract these immune suppressive mechanisms, have shown significant success in promoting immune responses against cancer and can result in tumor regression in many patients. While inhibitors to CTLA-4 and the PD-1/PD-L1 axis are well-established for the clinical management of melanoma, many patients do not respond or develop resistance to these interventions. Concerted efforts have focused on combinations of approved therapies aiming to further augment positive outcomes and survival. While CTLA-4 and PD-1 are the most-extensively researched targets, results from pre-clinical studies and clinical trials indicate that novel agents, specific for checkpoints such as A2AR, LAG-3, IDO and others, may further contribute to the improvement of patient outcomes, most likely in combinations with anti-CTLA-4 or anti-PD-1 blockade. This review discusses the rationale for, and results to date of, the development of inhibitory immune checkpoint blockade combination therapies in melanoma. The clinical potential of new pipeline therapeutics, and possible future therapy design and directions that hold promise to significantly improve clinical prognosis compared with monotherapy, are discussed.

Expression and clinical significance of PD-L1, B7-H3, B7-H4 and TILs in human small cell lung Cancer (SCLC)

Background

Small cell lung cancer (SCLC) accounts for 10–15% of all lung malignancies and its prognosis is dismal. Although early studies have shown promising clinical activity of immune checkpoint blockers, the immune composition and expression of potentially actionable immunostimulatory targets in this malignancy are poorly understood.

Methods

Using multiplexed quantitative immunofluorescence (QIF), we measured the levels of 3 different B7 family ligands PD-L1, B7-H3, B7-H4 and major tumor infiltrating lymphocyte (TIL) subsets in 90 SCLC samples represented in tissue microarray format. Associations between the marker levels, clinicopathological variables and survival were studied.

Results

PD-L1 protein was detected in 7.3%, B7-H3 in 64.9% and B7-H4 in 2.6% of SCLC cases. The markers showed limited co-expression and were not associated with the level of TILs, age, gender and stage. Elevated B7-H4 was associated with shorter 5-year overall survival. The levels of CD3+, CD8+ and CD20+ TILs and the ratio of total/effector T-cells were significantly lower in SCLC than in non-small cell lung cancer. High levels of CD3+, but not CD8+ or CD20+ TILs were significantly associated with longer survival.

Conclusions

Taken together, our study indicate variable expression and clinical role of B7-family ligands in SCLC with predominant expression of the candidate target B7-H3 and the presence of a limited cytotoxic anti-tumor immune response. These results support the evaluation of B7-H3 blockers and/or pro-inflammatory therapies in SCLC.

T cell-redirecting bispecific antibodies in cancer immunotherapy: recent advances

PURPOSE

Globally, cancer is a critical illness which seriously threatens human health. T-cell-based cancer immunotherapy for some patients has demonstrated impressive achievements including chimeric antigen receptor T cells, immune checkpoint inhibitors and T cell-redirecting bispecific antibodies (TRBAs). TRBAs recruit T cells to lyse cancer cells bypassing the antigen presentation through the major histocompatibility complex pathways. In this review we summarized the TRBAs formats, biophysical characteristics, the preclinical and clinical trial results, as well as the challenges faced by TRBAs in tumour therapy.

METHODS

Herein the relevant literature and clinical trials from the PubMed and ClinicalTrials.gov database.

RESULTS

The advances in protein engineering technology have generated diverse TRBAs format which can be classified into two categories: IgG-like TRBAs and non-IgG-like TRBAs. Multiple applications of TRBAs showed encouraging curative effect and entered clinical trials for lymphoid malignancy and solid tumour.

CONCLUSIONS

TRBA is a powerful tool for the cancer treatment and the clinical studies showed potent anti-tumour efficacy in hematologic malignancies. Although the clinical outcomes of TRBAs in solid tumours are less satisfied than hematologic malignancies, many preclinical antibodies and combination therapies are being evaluated.

Antitumor Responses in the Absence of Toxicity in Solid Tumors by Targeting B7-H3 via Chimeric Antigen Receptor T Cells

The high expression across multiple tumor types and restricted expression in normal tissues make B7-H3 an attractive target for immunotherapy. We generated chimeric antigen receptor (CAR) T cells targeting B7-H3 (B7-H3.CAR-Ts) and found that B7-H3.CAR-Ts controlled the growth of pancreatic ductal adenocarcinoma, ovarian cancer and neuroblastoma in vitro and in orthotopic and metastatic xenograft mouse models, which included patient-derived xenograft. We also found that 4-1BB co-stimulation promotes lower PD-1 expression in B7-H3.CAR-Ts, and superior antitumor activity when targeting tumor cells that constitutively expressed PD-L1. We took advantage of the cross-reactivity of the B7-H3.CAR with murine B7-H3, and found that B7-H3.CAR-Ts significantly controlled tumor growth in a syngeneic tumor model without evident toxicity. These findings support the clinical development of B7-H3.CAR-Ts.

Association of increased B7 protein expression by infiltrating immune cells with progression of gastric carcinogenesis

B7 negative costimulatory molecules are a group of molecules associated with the occurrence, development, and therapy of cancers. Here, we aimed to determine the clinical significance of PD-L1, B7-H3, and B7-H4 and their expression in CD8 and CD68 positive cells at different stages of gastric carcinogenesis.We detected PD-L1, B7-H3, B7-H4, CD8, and CD68 expression in samples by immunohistochemical staining of 62 chronic superficial gastritis (CSG) samples, 72 chronic atrophic gastritis (CAG) samples, 68 low-grade intraepithelial neoplasia (LIN) samples, 65 high-grade intraepithelial neoplasia (HIN) samples obtained from gastroscopic biopsies and 50 gastric adenocarcinoma (GA) samples obtained from surgical resections. Then we statistically analyzed the expression differences and correlations.Our results indicated that B7 and CD68 expression on infiltrating immune cells was associated with disease progression. However, infiltration of CD8+ cells decreased with disease progression. B7-H3 expression was markedly enhanced at neoplasia and GA stages. B7-H3 in tumor cells was negatively correlated with CD8-expressing cells. Conversely, B7-H3 expression in tumor-infiltrating immune cells was positively correlated with CD68-expressing cells. B7-H4 expression was found in the cell membrane at the stages of gastritis and low-grade neoplasia and was gradually expressed in the cytoplasm at high-grade neoplasia and GA stages. High B7-H4 expression in infiltrating immune cells was also significantly associated with lower CD8-positive and higher CD68-positive cell densities.Increased B7 protein expression by infiltrating immune cells was associated with disease progression, and specifically, the level of B7-H3 expression and localization of B7-H4 expression differed significantly among different stages of gastric carcinogenesis.

Bispecific anti-CD3 x anti-B7-H3 antibody mediates T cell cytotoxic ability to human melanoma in vitro and in vivo

Inhibition of the B7-H3 immune checkpoint is reported to limit the tumor growth of B7-H3⁺ tumors. In this study, we demonstrated B7-H3 expression in human melanoma cells, including a primary culture and several cell lines. Furthermore, we investigated whether B7-H3 could serve as a target for T cell-mediated immunotherapy against melanoma. The cytotoxic capacity of activated T cells (ATCs) armed with an anti-CD3 x anti-B7-H3 bispecific antibody (B7-H3Bi-Ab) to melanoma cells was measured using a bioluminescent signal through a luciferase reporter on tumor cells. In contrast to unarmed ATCs, B7-H3Bi-Ab-armed ATCs exhibited increased cytotoxicity against melanoma cells at effector/target ratios from 1:1 to 20:1. Moreover, B7-H3Bi-Ab-armed ATCs secreted more interferin-gamma (IFN-γ), accompanied by higher levels of activating marker CD69 and CD25 expression. Infusion of B7-H3Bi-Ab-armed ATCs suppressed melanoma growth in a xenograft mouse model. Taken together, our results indicate that B7-H3Bi-Ab-armed ATCs may be a promising approach to immunotherapy for melanoma patients.

Advances in neuroblastoma therapy

PURPOSE OF REVIEW

Our understanding of the biologic basis of neuroblastoma, the genetic heterogeneity of this malignancy and the role of host factors has expanded significantly in recent years. In this review, we highlight current and future risk-based treatment approaches and discuss the opportunities and challenges of selecting optimal therapies for specific patient subsets.

RECENT FINDINGS

Significant progress has been made in understanding neuroblastoma predisposition and new approaches have been taken to treatment of this disease. Although survival remains poor for patients with high-risk neuroblastoma, current-era therapy has improved outcomes. Integration of new prognostic markers into neuroblastoma classification systems will allow more precise risk classification and refined treatment assignment. Promising treatments that include targeted therapies as well as immunotherapeutics are being evaluated in clinical trials, and new predictive biomarkers are being developed.

SUMMARY

As our understanding of neuroblastoma biology deepens, our approaches to therapy for this disease continue to evolve. Improved risk stratification and the use of predictive biomarkers will aid in treatment selection for patients with neuroblastoma, and it is expected that future treatments will be associated with greater efficacy and less toxicity.

Advances in immune checkpoint inhibitors for bone sarcoma therapy

Bone sarcomas are a collection of sporadic malignancies of mesenchymal origin. The most common subtypes include osteosarcoma, Ewing sarcoma, chondrosarcoma, and chordoma. Despite the use of aggressive treatment protocols consisting of extensive surgical resection, chemotherapy, and radiotherapy, outcomes have not significantly improved over the past few decades for osteosarcoma or Ewing sarcoma patients. In addition, chondrosarcoma and chordoma are resistant to both chemotherapy and radiation therapy. There is, therefore, an urgent need to elucidate which novel new therapies may affect bone sarcomas. Emerging checkpoint inhibitors have generated considerable attention for their clinical success in a variety of human cancers, which has led to works assessing their potential in bone sarcoma management. Here, we review the recent advances of anti-PD-1/PD-L1 and anti-CTLA-4 blockade as well as other promising new immune checkpoint targets for their use in bone sarcoma therapy.

Value of bile soluble B7H3 for the diagnosis of malignant biliary strictures: Results of a retrospective study

AIMS

Increasing evidence has demonstrated that serum soluble B7H3(sB7-H3) is a useful tumor marker for cancer diagnosis and prognostic evaluations. Whether sB7-H3 expressed in the bile is related to the progression of malignant biliary strictures must be clarified.

METHODS

Bile sB7-H3 was obtained via endoscopic retrograde cholangiopancreatography (ERCP) from 323 patients suspected to have malignant biliary strictures and was detected using a B7H3 ELISA kit. Diagnostic value was compared among bile sB7-H3, CA19-9, CA12-5, and CEA and ERCP-based cytological/tissue examination. Additionally, the correlations between the bile sB7-H3 concentration and the clinical characteristics of malignant biliary strictures were studied.

RESULTS

The bile sB7-H3 levels of patients with malignant biliary strictures were significantly higher than those in patients with benign biliary strictures (P < 0.001). The AUC values of the receiver operating characteristic(ROC) curves for CA19-9, CA12-5 and CEA were 0.764, 0.475 and 0.399, respectively, which were significantly lower than that of sB7-H3 (0.878); the sensitivities of ERCP-based cytological and tissue examinations were 55.7% and 66.4%, respectively, which were far lower than that of bile sB7-H3(81.2%). A high level of sB7-H3 in patients with malignant biliary strictures was found to be correlated with vascular invasion(P < 0.001), lymph node metastasis(P < 0.001), distant metastasis (P < 0.001) and tumor-node-metastasis (TNM) stage(P = 0.01). The overall survival rate of the patients in the high sB7-H3 group was significantly lower than that of the patients in the low sB7-H3 group(P = 0.014).

CONCLUSIONS

Bile sB7-H3 could serve as a valuable biomarker for patients with malignant biliary strictures and high levels of bile sB7-H3 were associated with poor clinical outcomes.

The CD28-B7 Family of Co-signaling Molecules

Immune responses are controlled by the optimal balance between protective immunity and immune tolerance. T-cell receptor (TCR) signals are modulated by co-signaling molecules, which are divided into co-stimulatory and co-inhibitory molecules. By expression at the appropriate time and location, co-signaling molecules positively and negatively control T-cell differentiation and function. For example, ligation of the CD28 on T cells provides a critical secondary signal along with TCR ligation for naive T-cell activation. In contrast, co-inhibitory signaling by the CD28-B7 family is important to regulate immune homeostasis and host defense, as these signals limit the strength and duration of immune responses to prevent autoimmunity. At the same time, microorganisms or tumor cells can use these pathways to establish an immunosuppressive environment to inhibit the immune responses against themselves. Understanding these co-inhibitory pathways will support the development of new immunotherapy for the treatment of tumors and autoimmune and infectious diseases. Here, we introduce diverse molecules belonging to the members of the CD28-B7 family.

A Systematic Review of miR-29 in Cancer

MicroRNAs (miRNA) are small non-coding RNAs (∼22 nt in length) that are known as potent master regulators of eukaryotic gene expression. miRNAs have been shown to play a critical role in cancer pathogenesis, and the misregulation of miRNAs is a well-known feature of cancer. In recent years, miR-29 has emerged as a critical miRNA in various cancers, and it has been shown to regulate multiple oncogenic processes, including epigenetics, proteostasis, metabolism, proliferation, apoptosis, metastasis, fibrosis, angiogenesis, and immunomodulation. Although miR-29 has been thoroughly documented as a tumor suppressor in the majority of studies, some controversy remains with conflicting reports of miR-29 as an oncogene. In this review, we provide a systematic overview of miR-29's functional role in various mechanisms of cancer and introspection on the contradictory roles of miR-29.

Spotlight on dinutuximab in the treatment of high-risk neuroblastoma: development and place in therapy

Neuroblastoma (NB) is a pediatric cancer of the sympathetic nervous system which accounts for 8% of childhood cancers. Most NBs express high levels of the disialoganglioside GD2. Several antibodies have been developed to target GD2 on NB, including the human/mouse chimeric antibody ch14.18, known as dinutuximab. Dinutuximab used in combination with granulocyte-macrophage colony-stimulating factor, interleukin-2, and isotretinoin (13-cis-retinoic acid) has a US Food and Drug Administration (FDA)-registered indication for treating high-risk NB patients who achieved at least a partial response to prior first-line multi-agent, multimodality therapy. The FDA registration resulted from a prospective randomized trial assessing the benefit of adding dinutuximab + cytokines to post-myeloablative maintenance therapy for high-risk NB. Dinutuximab has also shown promising antitumor activity when combined with temozolomide and irinotecan in treating NB progressive disease. Clinical activity of dinutuximab and other GD2-targeted therapies relies on the presence of the GD2 antigen on NB cells. Some NBs have been reported as GD2 low or negative, and such tumor cells could be nonresponsive to anti-GD2 therapy. As dinutuximab relies on complement and effector cells to mediate NB killing, factors affecting those components of patient response may also decrease dinutuximab effectiveness. This review summarizes the development of GD2 antibody-targeted therapy, the use of dinutuximab in both up-front and salvage therapy for high-risk NB, and the potential mechanisms of resistance to dinutuximab.

Enhancing Anti-PD-1/PD-L1 Immune Checkpoint Inhibitory Cancer Therapy by CD276-Targeted Photodynamic Ablation of Tumor Cells and Tumor Vasculature

Antiangiogenic therapies have been demonstrated to improve the efficacy of immune checkpoint inhibition by overcoming the immunosuppressive status of the tumor microenvironment. However, most of the current antiangiogenic agents cannot discriminate tumor angiogenesis from physiological angiogenesis. The aim of this study was to investigate whether a photodynamic therapy (PDT) agent that targets CD276, a receptor overexpressed in various tumor cells and tumor vasculature but with limited expression in normal tissue vasculature, could improve the tumor inhibitory efficacy of a PD-1/PD-L1 blockade. A CD276-targeting agent (IRD-αCD276/Fab) was synthesized by conjugating the Fab fragment of an anti-CD276 antibody with a photosensitizer IRDye700. The in vivo tumor-targeting efficacy and therapeutic effects of IRD-αCD276/Fab with or without an anti-PD-1/PD-L1 blockade were tested in subcutaneous and lung metastatic tumor models. PDT using IRD-αCD276/Fab significantly suppressed the growth of subcutaneous 4T1 tumor and inhibited its lung metastasis. Moreover, it triggered in vivo antitumor immunity by increasing the activation and maturation of dendritic cells. Tumor PD-L1 levels were also markedly increased after PDT using IRD-αCD276/Fab, as evidenced by noninvasive PD-L1-targeted small-animal PET imaging. In combination with an anti-PD-1/PD-L1 blockade, IRD-αCD276/Fab PDT markedly suppressed the growth of tumors and prevented their metastasis to the lung by recruiting the tumor infiltration of CD8⁺ T cells. Our data provide evidence for the role of CD276-targeted PDT for local immune modulation, and its combination with PD-L1/PD-1 axis inhibition is a promising strategy for eliminating primary tumors as well as disseminated metastases, by generating local and systemic antitumor responses.

CD276 (B7-H3) Maintains Proliferation and Regulates Differentiation in Angiogenic Function in Late Endothelial Progenitor Cells

Endothelial progenitor cells (EPCs) provide an important source of recovery from blood vessel dysfunction. Late EPCs (LEPCs) are circulating blood cells that are capable of promoting vascular repair. Using transcriptome analysis, we identified distinctive LEPC profiles and found that CD276 (B7-H3) mRNA is strongly expressed in LEPCs. CD276 protein is present abundantly on the cell surface of LEPC when analyzed by fluorescence-activated cell sorter and immunocytochemistry. CD276, a B7 family member, is a type I transmembrane glycoprotein. The role of CD276 in LEPCs remains unknown. CD276 knockdown by lentivirus transduction in LEPCs significantly decreased proliferation and increased apoptosis of LEPCs in vitro. After CD276 silencing, the cell cycle of LEPCs was prone to remain at the G0/G1 phase, and the cell migration rates as well as transwell and wound-healing migration were decreased. CD276 knockdown in LEPCs increased the G1 phase regulators cyclin D2/D3/E1-cyclin-dependent kinases (CDK2/4/6), but decreased the S-G2-M phase regulators cyclin A/B-CDK1. However, LEPCs with CD276 knockdown resulted in increased tube formation in vitro and angiogenesis in a Matrigel plug assay in vivo. FoxC1/C2, an upstream signal of Notch in arterial cell proliferation, and Hey1/2, which is known to promote arterial differentiation in the vasculature, were upregulated in CD276 knockdown LEPCs. In LEPCS, CD276 has a positive effect on proliferation and migration of endothelial cells, but negative effects on angiogenesis, particularly endothelial cell differentiation. Our data indicate, for therapeutic purpose, that CD276 can be used to acquire and maintain cell populations of LEPCs and blocking CD276 will promote angiogenetic differentiation. We found that CD276 (B7-H3) is enriched on the cell membrane of LEPCs. CD276 knockdown reduced proliferation and migration of LEPCs by increasing cell cycle inhibitors such as p21^cip1 and pRb and decreasing pErk1/2 and pAkt but promoted angiogenesis and endothelial cell differentiation by elevating vascular endothelial growth factor-vascular endothelial growth factor receptor 1 and p-p38. Stem Cells 2019;37:382-394.

[Risk-adapted (immuno)therapy for renal cell carcinoma]

The introduction of immunotherapy into the therapeutic algorithm of metastatic renal cell carcinoma (mRCC) represents the most recent expansion of the therapy landscape. This provides a new therapeutic axis in addition to targeted therapies. At the same time, the development of new tyrosine kinase inhibitors (TKIs) has led to an improvement in the effectiveness of targeted therapies. Cabozantinib and tivozanib are two new first-line options that redefine the existing therapy algorithm. The importance of the checkpoint blockade in the first line is clinically undisputed; however, approval of the immune combination ipilimumab + nivolumab has not yet been granted. An important task now is to offer risk-adapted therapy in order to optimally balance efficacy and risks of systemic therapy, thereby ensuring the best possible individual therapy.

CAR T Cell Therapy for Neuroblastoma

Patients with high risk neuroblastoma have a poor prognosis and survivors are often left with debilitating long term sequelae from treatment. Even after integration of anti-GD2 monoclonal antibody therapy into standard, upftont protocols, 5-year overall survival rates are only about 50%. The success of anti-GD2 therapy has proven that immunotherapy can be effective in neuroblastoma. Adoptive transfer of chimeric antigen receptor (CAR) T cells has the potential to build on this success. In early phase clinical trials, CAR T cell therapy for neuroblastoma has proven safe and feasible, but significant barriers to efficacy remain. These include lack of T cell persistence and potency, difficulty in target identification, and an immunosuppressive tumor microenvironment. With recent advances in CAR T cell engineering, many of these issues are being addressed in the laboratory. In this review, we summarize the clinical trials that have been completed or are underway for CAR T cell therapy in neuroblastoma, discuss the conclusions and open questions derived from these trials, and consider potential strategies to improve CAR T cell therapy for patients with neuroblastoma.

Downregulated miR-187 contributes to the keratinocytes hyperproliferation in psoriasis

Psoriasis is a common chronic skin disease characterized by epidermal hyperplasia and inflammation. However, the pathogenesis of psoriasis is multifactorial and is not fully understood. MicroRNAs (miRNAs) represent a promising class of small, noncoding RNA molecules that have a large impact on cellular functions by regulating gene expression. Here we reported that microRNA-187 (miR-187), which is one of the most dynamic microRNAs identified in the deep screening miRNAs profile, is downregulated in inflammatory cytokines-stimulated keratinocytes and psoriatic skins. By luciferase activity assay and gain-of-function studies, we showed that miR-187 inhibits keratinocytes hyperproliferation by targeting CD276. Moreover, overexpression of miR-187 decreases acanthosis and reduces the disease severity in psoriasis mouse models. Taken together, the results of our study implies miR-187 as a critical factor in psoriasis pathogenesis, which could be a potent target for psoriasis treatment.

Profiling targetable immune checkpoints in osteosarcoma

Osteosarcomas are aggressive bone tumors for which therapeutic advances have not improved over several decades. Unlike most pediatric tumors, the osteosarcoma genome is remarkably unstable, characterized by numerous copy number alterations and chromosomal structural aberrations. In this study, we asked if the targetable immune checkpoints CD274 (PD-L1), PDCD1LG2 (PD-L2), CD276 (B7-H3) and IDO1 are impacted by copy number alterations in osteosarcoma. Of the 215 osteosarcoma samples investigated, PD-L1/PD-L2, B7-H3 and IDO1 were independently gained at frequencies of approximately 8-9%, with a cumulative frequency of approximately 24%. RNA sequencing data from two independent cohorts revealed that B7-H3 is the most highly expressed immune checkpoint gene among the four investigated. We also show that IDO1 is preferentially expressed in pediatric solid tumors and that increased protein expression of B7-H3 and IDO1 are significantly associated with inferior survival in patient samples. Using human osteosarcoma cell lines, we demonstrate that IDO1 is gained in MG63 and G292 cells and that the IDO1 inhibitor, epacadostat, inhibits the enzymatic activity of IDO1 in a dose-dependent manner in these cells. Together, these data reveal the genomic and transcriptomic profiles of PD-L1, PD-L2, B7-H3 and IDO1 in osteosarcoma and identifies a potential context for targeted immunotherapeutic intervention in a subset of patients.

Identification of PD-L2, B7-H3 and CTLA-4 immune checkpoint proteins in genetic subtypes of meningioma

Meningioma is the most common brain tumor in adults. Surgical resection remains the primary treatment. No chemotherapy exists. However, gene mutations now could explain ~ 80% of meningioma and targeted therapies based on these are being investigated. Furthermore, with the recent discovery of PD-L1 in malignant meningioma, clinical trials using immunotherapy have commenced. Here, we report for the first time the expression profiles of immune checkpoint proteins PD-L2, B7-H3 and CTLA-4 in meningioma and their association to common gene mutations. PD-L2 and B7-H3 expression was significantly greater than all immune checkpoint proteins studied, and particularly elevated in patients with gene mutations affecting the PI3K/AKT/mTOR pathway. CTLA-4 expressing CD3+ lymphocytes were observed in atypical and malignant meningioma and tumors harboring a PIK3CA or SMO mutation. These results identify novel targets for immunotherapy irrespective of grade and distinguish potential patient populations based on genetic classification for stratification into checkpoint inhibitor clinical trials.

B7-H3 on circulating epithelial tumor cells correlates with the proliferation marker, Ki-67, and may be associated with the aggressiveness of tumors in breast cancer patients

Circulating epithelial tumor cells (CETCs) in peripheral blood are a prerequisite for the development of metastases. B7-H3 is an important immune checkpoint member of the B7 family and inhibits T-cell mediated antitumor immunity. Its expression is associated with a negative prognosis and a poor clinical outcome. Based on the clinical success of inhibitory immune checkpoint blockade, monoclonal antibodies (mAbs) against B7-H3 appear to be a promising therapeutic strategy. The proliferation biomarker, Ki-67, is used as a prognostic factor for breast cancer and reflects the proliferative potential of the tumor. In order to better understand the role of B7-H3 and Ki-67 in cancer development, in this study, we used a real-time biopsy for determining both biomarkers on CETCs in breast cancer patients. Blood from 50 patients suffering from breast cancer was analyzed for CETCs and the expression of B7-H3 and Ki-67 using the maintrac® method. B7-H3 expression on CETCs was found in 82% of the patients. The frequency of B7-H3- and Ki-67‑positive CETCs was significantly higher in patients who had received radiation therapy compared to patients who had not received irradiation. B7-H3‑positive CETCs seemed to be more aggressive as the percentage of B7-H3‑positive CETCs correlated with the percentage of cells positive for the proliferation marker, Ki-67 (r=0.72 P<0.001). A significant association between the Ki-67 and B7-H3 expression level on the CETCs and nodal status was observed. On the whole, the findings of this study indicate that breast cancer patients have detectable CETCs with a high frequency of B7-H3 expression regardless of the stage of the disease. B7-H3 seems to be an important factor in immune evasion and may thus be a promising target for anticancer therapies. Radiation may lead to an upregulation of B7-H3 expression on CETCs, which could be a possible mechanism of acquired radio-resistance.

Large-scale analysis reveals the specific clinical and immune features of B7-H3 in glioma

Background: B7-H3 is an immune checkpoint member that belongs to B7-CD28 families and plays a vital role in the inhibition of T-cell function. Importantly, B7-H3 is widely overexpressed on solid tumors, making it become an attractive target for cancer immunotherapy. To clarify the expression panel of B7-H3 in glioma, we explored the clinical and immune features of B7-H3 expression in a large-scale study. Methods and patients: Totally, 1323 glioma samples from Chinese Glioma Genome Atlas (CGGA) dataset, including 325 RNAseq data and 301 mRNA microarray data, and The Cancer Genome Atlas (TCGA) dataset, including 697 RNAseq data, were gathered into our research. The statistical analysis and graphical work were mainly realized by R language. Results: B7-H3 expression was found positively correlated with the grade of malignancy, which might be caused by hypomethylation. The expression level of B7-H3 was consistently up-regulated in IDH wild-type glioma and highly enriched in mesenchymal subtype. GSEA analysis suggested that B7-H3 related genes were more involved in immune response and angiogenesis in glioma. Moreover, B7-H3 showed a consistent positive relationship with stromal and immune cell populations. Further analysis confirmed that B7-H3 played an important role in T-cell-mediated immunity, especially in T-cell-mediated immune response to tumor cell. Circos plots revealed that B7-H3 was tightly associated with most B7 members and other immune checkpoints. Univariate and multivariate cox analysis demonstrated that B7-H3 was an independent prognosticator for glioma patients. Conclusion: B7-H3 represents the malignant phenotype of glioma and independently predicted worse prognosis in glioma patients. Moreover, B7-H3 collaborating with other checkpoint members may contribute to the dysfunctional phenotype of T cell. These findings will be helpful for further optimizing immunotherapies for glioma.

Clinical correlation of B7-H3 and B3GALT4 with the prognosis of colorectal cancer

AIM

To investigate the expression and clinical significance of B7 homolog 3 (B7-H3) and β-1,3-galactosyltransferase-4 (B3GALT4) in colorectal cancer (CRC) patients.

METHODS

Using tissue microarray, we identified the expression of B7-H3 and B3GALT4 in 223 CRC patient samples by immunohistochemistry and evaluated the possible correlation between B7-H3 and B3GALT4 and clinical outcomes. Further, the mRNA and protein expression were identified to establish the regulatory relationship of B7-H3 with B3GALT4 in vitro.

RESULTS

A significant positive correlation between B7-H3 and B3GALT4 was observed in CRC specimens (r = 0.219, P = 0.001). High expression of B7-H3 was identified as a significant independent predictor of poor overall survival (OS) [hazard ratio (HR) = 1.781; 95%CI: 1.027-3.089; P = 0.040]. Moreover, high expression of B3GALT4 was also recognized as an independent predictor of inferior OS (HR = 1.597; 95%CI: 1.007-2.533; P = 0.047). Additionally, CRC patients expressing both high B7-H3 and high B3GALT4 contributed to a significant decrease in OS (HR = 2.283; 95%CI: 1.289-4.042; P = 0.005). In CRC cell lines with stable expression of high B7-H3, the mRNA and protein expressions of B3GALT4 were significantly upregulated. Similarly, the expression of B3GALT4 was significantly reduced when expression of B7-H3 was knocked down.

CONCLUSION

The expression of B3GALT4 in CRC is positively correlated with B7-H3 expression in vitro. B7-H3/B3GLAT4 may be used as dual prognostic biomarkers for CRC.

Immunological-based approaches for cancer therapy

The immunologic landscape of tumors has been continuously unveiled, providing a new look at the interactions between cancer cells and the immune system. Emerging tumor cells are constantly eliminated by the immune system, but some cells establish a long-term equilibrium phase leading to tumor immunoediting and, eventually, evasion. During this process, tumor cells tend to acquire more mutations. Bearing a high mutation burden leads to a greater number of neoantigens with the potential to initiate an immune response. Although many tumors evoke an immune response, tumor clearance by the immune system does not occur due to a suppressive tumor microenvironment. The mechanisms by which tumors achieve the ability to evade immunologic control vary. Understanding these differences is crucial for the improvement and application of new immune-based therapies. Much effort has been placed in developing in silico algorithms to predict tumor immunogenicity and to characterize the microenvironment via high-throughput sequencing and gene expression techniques. Each sequencing source, transcriptomics, and genomics yields a distinct level of data, helping to elucidate the tumor-based immune responses and guiding the fine-tuning of current and upcoming immune-based therapies. In this review, we explore some of the immunological concepts behind the new immunotherapies and the bioinformatic tools to study the immunological aspects of tumors, focusing on neoantigen determination and microenvironment deconvolution. We further discuss the immune-based therapies already in clinical use, those underway for future clinical application, the next steps in immunotherapy, and how the characterization of the tumor immune contexture can impact therapies aiming to promote or unleash immune-based tumor elimination.

The type 1 transmembrane glycoprotein B7-H3 interacts with the glycolytic enzyme ENO1 to promote malignancy and glycolysis in HeLa cells

The role of the type 1 transmembrane glycoprotein B7-H3 is controversial in tumorigenesis; thus, a better clarification of its involvement in cancer is crucial. In the present study, 79.3% of cervical cancer samples were found to be B7-H3 positive and the expression of B7-H3 was positively correlated with the clinical features of the samples. Silencing B7-H3 using small interfering RNA or blocking it with intracellular ScFv attenuated the malignancy of HeLa cells. By pull-down assay and liquid chromatography-mass spectrometry in HeLa cells, the glycolytic enzyme ENO1 was found to interact with B7-H3. Subsequently, the involvement of B7-H3 in glycolysis was investigated. We observed decreases in the levels of ATP and lactate, as well as c-Myc and lactate dehydrogenase A, upon B7-H3 downregulation in HeLa cells. The results of the present study provide evidence for B7-H3 mediating tumor glycolysis.

Tumor B7-H3 (CD276) Expression and Survival in Pancreatic Cancer

B7-H3 (CD276), a member of the family of immune modulators, orchestrates antitumor immunity. To date, only small-sized studies have examined the association of B7-H3 expression with survival in pancreatic cancer, yielding inconclusive results. We evaluated tumor B7-H3 expression in 150 consecutive patients with pancreatic ductal adenocarcinoma using immunohistochemistry. B7-H3 expression was positive (≥10% tumor cells) in 99 of 150 (66%) cases of pancreatic cancer. We classified the tumors into four groups depending on B7-H3 expression (negative, low, intermediate, and high) and found that higher B7-H3 expression was independently associated with lower disease-free survival (DFS; for high vs. negative B7-H3 expression: multivariable hazard ratio (HR) = 3.12; 95% confidence interval (CI) = 1.48⁻6.15; Ptrend = 0.0026). Furthermore, the association of B7-H3 expression with survival differed according to the pathological stage (p-stage) (Pinteraction = 0.048, between p-stages I⁻II and III⁻IV). The association of B7-H3 positivity with lower DFS was stronger in tumors with p-stage I⁻II (multivariable HR = 3.10, 95% CI = 1.75⁻5.69; P < 0.0001) than in those with p-stage III⁻IV (multivariable HR = 1.20, 95% CI = 0.67⁻2.28; P = 0.55). We demonstrated that tumor high B7-H3 expression is independently associated with poor survival in patients with pancreatic cancer and that this association is stronger in tumors with p-stage I⁻II than in those with p-stage III⁻IV. B7-H3 expression may be a useful prognostic biomarker for identifying aggressive early-stage pancreatic cancer.

B7-H3 expression and its correlation with clinicopathologic features, angiogenesis, and prognosis in intrahepatic cholangiocarcinoma

This study was designed to explore the expression of B7-H3 in human intrahepatic cholangiocarcinoma (ICC) and its association with the clinicopathologic factors. In the current study, the expression of B7-H3 in 45 patients with intrahepatic cholangiocarcinoma and 8 patients with hepatolithiasis was analyzed by immunohistochemistry, which revealed that B7-H3 was not expressed in hepatolithiatic tissues, but positively expressed in 57.8% (26/45) of the ICC cases. The expression of B7-H3 was significantly associated with lymph node metastases and venous invasion. A positive correlation was also observed between the expression of B7-H3 and MVD, an index for tumor angiogenesis. Further survival analysis indicated that patients with B7-H3 negative expression had higher overall survival (OS) and cancer-specific survival (CSS) rates than those with B7-H3 positive expression. Multivariate analysis revealed that B7-H3 expression was an independent prognostic indicator for poor OS and CSS of ICC patients. Our results suggest that B7-H3 may be a valuable biomarker in determining tumor progression and prognosis of intrahepatic cholangiocarcinoma. It is also a potential target for antivascular therapy of ICC.

The Correlation Between the Immune and Epithelial-Mesenchymal Transition Signatures Suggests Potential Therapeutic Targets and Prognosis Prediction Approaches in Kidney Cancer

Both epithelial-mesenchymal transition (EMT) and immune regulation are important biological process in malignant tumours. The current research aims to comprehensively explore the potential association between the epithelial-mesenchymal transition (EMT) signature and immune checkpoint signature and its role in predicting the prognosis of clear-cell renal cell carcinoma (ccRCC) patients. EMT-related genes were collected from an experiment-based study and then were investigated using data from the Cancer Genome Atlas. A total of 357 genes were included, and 23 of them that were upregulated and correlated with prognosis were analysed further as core EMT genes in ccRCC. Interestingly, the emerging immune checkpoints CD276, OX40 and TGFB1 were found to be significantly co-expressed with core EMT genes, and TGFB1, CXCR4, IL10, and IL6 were the most important molecules potentially interacting with EMT molecules in our model, as determined from mRNA co-expression and protein-protein interaction network analysis. Additionally, an integrated scoring model based on FOXM1, TIMP1 and IL6 was successfully established to distinguish ccRCC patients with different clinical risks. Our results identified core genes in the EMT-immunophenotyping correlation and evaluated their risk assessment capabilities, providing more potential therapeutic targets and prediction approaches regarding the translational research of treatment and prognosis in ccRCC.

B7-H3 in Cancer - Beyond Immune Regulation

B7-H3, a member of the B7 family of immunoregulatory proteins, is overexpressed in cancer and promotes tumor growth, metastasis, and drug resistance. We discuss here the involvement of B7-H3 in cancer that goes beyond its immune regulatory function, and discuss the potential of B7-H3 as a biomarker and therapeutic target.

Next generation of immune checkpoint therapy in cancer: new developments and challenges

Immune checkpoints consist of inhibitory and stimulatory pathways that maintain self-tolerance and assist with immune response. In cancer, immune checkpoint pathways are often activated to inhibit the nascent anti-tumor immune response. Immune checkpoint therapies act by blocking or stimulating these pathways and enhance the body's immunological activity against tumors. Cytotoxic T lymphocyte-associated molecule-4 (CTLA-4), programmed cell death receptor-1 (PD-1), and programmed cell death ligand-1(PD-L1) are the most widely studied and recognized inhibitory checkpoint pathways. Drugs blocking these pathways are currently utilized for a wide variety of malignancies and have demonstrated durable clinical activities in a subset of cancer patients. This approach is rapidly extending beyond CTLA-4 and PD-1/PD-L1. New inhibitory pathways are under investigation, and drugs blocking LAG-3, TIM-3, TIGIT, VISTA, or B7/H3 are being investigated. Furthermore, agonists of stimulatory checkpoint pathways such as OX40, ICOS, GITR, 4-1BB, CD40, or molecules targeting tumor microenvironment components like IDO or TLR are under investigation. In this article, we have provided a comprehensive review of immune checkpoint pathways involved in cancer immunotherapy, and discuss their mechanisms and the therapeutic interventions currently under investigation in phase I/II clinical trials. We also reviewed the limitations, toxicities, and challenges and outline the possible future research directions.

Immunohistochemical and Image Analysis-Based Study Shows That Several Immune Checkpoints are Co-expressed in Non-Small Cell Lung Carcinoma Tumors

INTRODUCTION

The understanding of immune checkpoint molecules' co-expression in non-small cell lung carcinoma (NCLC) is important to potentially design combinatorial immunotherapy approaches.

METHODS

We studied 225 formalin-fixed, paraffin-embedded tumor tissues from stage I-III NCLCs - 142 adenocarcinomas (ADCs) and 83 squamous cell carcinomas (SCCs) - placed in tissue microarrays. Nine immune checkpoint markers were evaluated; four (programmed death ligand 1 [PD-L1], B7-H3, B7-H4, and indoleamine 2,3-dioxygenase 1 [IDO-1]) expressed predominantly in malignant cells (MCs) and five (inducible T cell costimulator, V-set immunoregulatory receptor, T-cell immunoglobulin mucin family member 3, lymphocyte activating 3, and OX40) expressed mostly in stromal tumor-associated inflammatory cells (TAICs). All markers were examined using a quantitative image analysis and correlated with clinicopathologic features, TAICs, and molecular characteristics.

RESULTS

Using above the median value as positive expression in MCs and high density of TAICs expressing those markers, we identified higher expression of immune checkpoints in SCC than ADC. Common simultaneous expression by MCs was PD-L1 + B7-H3 + IDO-1 in ADC and PD-L1 + B7-H3, or B7-H3 + B7-H4, in SCC. TAICs expressing checkpoint were significantly higher in current smokers than in never smokers. Almost all the immune checkpoint markers showed positive correlation with TAICs expressing inflammatory cell markers. KRAS-mutant ADC specimens showed higher expression of PD-L1 in MCs and of B7-H3, T-cell immunoglobulin mucin family member 3, and IDO-1 in TAICs than wild type. Kaplan-Meier survival curves showed worse prognosis in ADC patients with higher B7-H4 expression by MCs.

CONCLUSIONS

We found frequent immunohistochemical co-expression of immune checkpoints in surgically resected NCLC tumors and correlated with tumor histology, smoking history, tumor size, and the density of inflammatory cells and tumor mutational status.

Importance of immune monitoring approaches and the use of immune checkpoints for the treatment of diffuse intrinsic pontine glioma: From bench to clinic and vice versa (Review)

On the basis of immunological results, it is not in doubt that the immune system is able to recognize and eliminate transformed cells. A plethora of studies have investigated the immune system of patients with cancer and how it is prone to immunosuppression, due in part to the decrease in lymphocyte proliferation and cytotoxic activity. The series of experiments published following the demonstration by Dr Allison's group of the potential effect of anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) paved the way for a new perception in cancer immunotherapy: Immune checkpoints. Several T cell-co-stimulatory molecules including cluster of differentiation (CD)28, inducible T cell co-stimulatory, 4-1BB, OX40, glucocorticoid-induced tumor necrosis factor receptor-related gene and CD27, and inhibitory molecules including T cell immunoglobulin and mucin domain-containing-3, programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), V-domain immunoglobulin suppressor of T cells activation, T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain, and B and T lymphocyte attenuator have been described in regulating T cell functions, and have been demonstrated to be essential targets in immunotherapy. In preclinical studies, glioblastoma multiforme, a high-grade glioma, the monotherapy targeting PD-1/PD-L1 and CTLA-4 resulted in increased survival times. An improved understanding of the pharmacodynamics and immune monitoring on glioma cancers, particularly in diffuse intrinsic pontine glioma (DIPG), an orphan type of cancer, is expected to have a major contribution to the development of novel therapeutic approaches. On the basis of the recent preclinical and clinical studies of glioma, but not of DIPG, the present review makes a claim for the importance of investigating the tumor microenvironment, the immune response and the use of immune checkpoints (agonists or antagonists) in preclinical/clinical DIPG samples by immune monitoring approaches and high-dimensional analysis. Evaluating the potential predictive and correlative biomarkers in preclinical and clinical studies may assist in answering certain crucial questions that may be useful to improve the clinical response in patients with DIPG.

New developments in immunotherapy for pediatric solid tumors

PURPOSE OF REVIEW

Building upon preclinical advances, we are uncovering immunotherapy strategies that are translating into improved outcomes in tumor subsets. Advanced pediatric solid tumors carry poor prognoses and resultant robust efforts to apply immunotherapy advances to pediatric solid tumors are in progress. Here, we discuss recent developments in the field using mAb and mAb-based therapies including checkpoint blockade and chimeric antigen receptors (CARs).

RECENT FINDINGS

The pediatric solid tumor mAb experience targeting the diganglioside, GD2, for patients with neuroblastoma has been the most compelling to date. GD2 and alternative antigen-specific mAbs are now being incorporated into antibody-drug conjugates, bispecific antibodies and CARs for treatment of solid tumors. CARs in pediatric solid tumors have not yet achieved comparative responses to the hematologic CAR experience; however, novel strategies such as bispecific targeting, intratumoral administration and improved understanding of T-cell biology may yield enhanced CAR-efficacy. Therapeutic effect using single-agent checkpoint blocking antibodies in pediatric solid tumors also remains limited to date. Combinatorial strategies continue to hold promise and the clinical effect in tumor subsets with high antigenic burden is being explored.

SUMMARY

Pediatric immunotherapy remains at early stages of translation, yet we anticipate that with advanced technology, we will achieve widespread, efficacious use of immunotherapy for pediatric solid tumors.

Olive flounder CD276 (B7-H3) a coinhibitory molecule for T cells: Responses during viral hemorrhagic septicemia virus (VHSV) stimulation

Coinhibitory pathways in the B7-CD28 family provide critical inhibitory signals that regulate immune homeostasis, defense and protect tissue integrity. CD276 (B7-H3) is an important immune checkpoint member of this family, which is induced on antigen-presenting cells (APCs), and plays an important role in the inhibition of T-cell function. We have characterized the CD276 gene of olive flounder, Paralichthys olivaceus. OfCD276 has an ORF of 912 bp that codes for 303 amino acids with a predicted molecular mass of 33 kDa. It is a type I transmembrane protein with a single extracellular V- and C-like Ig domains, a transmembrane region, and a highly diverse cytoplasmic tail. This gene was distinctly expressed in gill, spleen, and skin, and sparsely expressed in other tissues. Pathogen stimulation by VHSV revealed that transcription of OfCD276 was induced on early hours in liver and expressed late in head kidney, spleen, intestine and gill tissues. Flow cytometry analysis of leukocytes revealed the percentage of granulocytes and lymphocytes that expressed OfCD276 molecules on their cell surface was 85.1% and 3.1%, respectively. Our study shows a significant role played by this coinhibitory molecule that participate in the regulation of the cell mediated immune response.

The immunocytokine L19-IL2: An interplay between radiotherapy and long-lasting systemic anti-tumour immune responses

Recently, we have shown that the administration of the tumour-targeted antibody-based immunocytokine L19-IL2 after radiotherapy (RT) resulted in synergistic anti-tumour effect. Here we show that RT and L19-IL2 can activate a curative abscopal effect, with a long-lasting immunological memory. Ionizing radiation (single dose of 15Gy, 5 × 2Gy or 5 × 5Gy) was delivered to primary C51 colon tumour-bearing immunocompetent mice in combination with L19-IL2 and response of secondary non-irradiated C51 or CT26 colon tumours was evaluated. 15Gy + L19-IL2 triggered a curative (20%) abscopal effect, which was T cell dependent. Moreover, 10Gy + L19-IL2 treated and cured mice were re-injected after 150 days with C51 tumour cells and tumour uptake was assessed. Age-matched controls (matrigel injected mice treated with 10Gy + L19-IL2, mice cured after treatment with surgery + L19-IL2 and mice cured after high dose RT 40Gy + vehicle) were included. Several immunological parameters in blood, tumours, lymph nodes and spleens were investigated. Treatment with 10Gy + L19-IL2 resulted in long-lasting immunological memory, associated with CD44⁺CD127⁺ expression on circulating T cells. This combination treatment can induce long-lasting curative abscopal responses, and therefore it has also great potential for treatment of metastatic disease. Preclinical findings have led to the initiation of a phase I clinical trial (NCT02086721) in our institute investigating stereotactic ablative radiotherapy with L19-IL2 in patients with oligometastatic solid tumours.

212Pb-labeled B7-H3-targeting antibody for pancreatic cancer therapy in mouse models

INTRODUCTION

We recently validated monoclonal antibody (mAb) 376.96 as an effective carrier for targeted α-particle radioimmunotherapy (RIT) with ²¹²Pb in ovarian cancer mouse models. In this study, we tested the binding of radiolabeled mAb 376.96 to human pancreatic ductal adenocarcinoma (PDAC) cells and localization in xenografts in immune-deficient mice and evaluated ²¹²Pb-labeled 376.96 (²¹²Pb-376.96) for PDAC therapy.

METHODS

In vitro Scatchard assays assessed the specific binding of ²¹²Pb-376.96 to human PDAC3 adherent differentiated cells and non-adherent cancer initiating cells (CICs) dissociated from tumorspheres. In vitro clonogenic assays were used to measure the proliferation of adherent PDAC3 cells and CIC-enriched tumorspheres treated with ²¹²Pb-376.96 or the irrelevant isotype-matched ²¹²Pb-F3-C25. Mice bearing patient derived pancreatic cancer Panc039 xenografts were i.v. injected with 0.17-0.70 MBq ²¹²Pb-376.96 or isotype control ²¹²Pb-F3-C25, and used for biodistribution and tumor growth inhibition studies. Mice bearing orthotopic PDAC3 xenografts were i.v. co-injected with ^99mTc-376.96 and ¹²⁵I-F3-C25 and used for biodistribution studies.

RESULTS

²¹²Pb-376.96 specifically bound to PDAC3 adherent and dissociated tumorsphere CICs; K_d values averaged 9.0 and 21.7 nM, respectively, with 10⁴-10⁵ binding sites/cell. ²¹²Pb-376.96 inhibited the clonogenic survival of PDAC3 cells or CICs dissociated from tumorspheres 3-6 times more effectively than isotype-matched control ²¹²Pb-F3-C25. Panc039 s.c. tumors showed significantly higher uptake of ²¹²Pb-376.96 (14.0 ± 2.1% ID/g) compared to ²¹²Pb-F3-C25 (6.5 ± 0.9% ID/g, p < .001) at 24 h after dosing. Orthotopic PDAC3 tumors showed significantly higher uptake of ^99mTc-376.96 (6.4 ± 1.8% ID/g) compared to ¹²⁵I-F3-C25 (3.9 ± 0.9% ID/g, p < .05) at 24 h after dosing. Panc039 tumor growth was significantly inhibited by ²¹²Pb-376.96 compared to ²¹²Pb-F3-C25 or non-treated control tumors (p < .05).

CONCLUSION

Our results provide evidence for the efficacy of B7-H3 targeted RIT against preclinical models of pancreatic ductal adenocarcinoma (PDAC) and support future studies with ²¹²Pb-376.96 in combination with chemotherapy to potentiate efficacy against PDAC.

Reduced sB7-H3 Expression in the Peripheral Blood of Systemic Lupus Erythematosus Patients

Both membrane-bound and soluble forms of costimulatory molecules play important roles in immune-regulatory networks. B7-H3, a member of the B7 family, has been found with aberrant expression in tumors and infectious disease. However, the significance of sB7-H3 expression in systemic lupus erythematosus (SLE) has not been investigated. Using the peripheral blood of 78 SLE patients, we established a comprehensive database containing clinical data and relevant laboratory tests. We found that sB7-H3 expression in SLE patients was significantly lower compared with the healthy individuals. In addition, sB7-H3 levels in the patients were positively correlated with the disease activity as indicated by SLE disease activity index score, rashes, fever, and inflammatory cytokines. Moreover, sB7-H3 was associated with the counts of red blood cells and hemoglobin. Our findings suggest that sB7-H3 might counteract the aberrant immune response and potentially serve as a monitoring indicator of disease progression and therapeutic target in SLE treatment.

Immune Surveillance Plays a Role in Locally Aggressive Giant Cell Lesions of Bone

BACKGROUND

Giant cell lesions are locally aggressive intraosseous neoplasms with capacity to metastasize. The role of immune surveillance in the pathophysiology of giant cell lesions is poorly understood, and understanding what role the immune system plays in giant cell lesions may lead to the development of more effective treatment. The aim of this study was to explore the role of immune surveillance in giant cell lesions by examining the expression of the HLA class I and class II antigens and tumor infiltrating lymphocytes. In addition, we examined the role of the immune modulating surface antigen B7-H3, which belongs to the B7 superfamily, a group of molecules that modulates T-cell responses.

QUESTIONS/PURPOSES

(1) Is an immune response elicited by giant cell lesions? (2) Do clinically relevant human leukocyte antigen (HLA) defects exist in giant cell lesions? (3) Is B7-H3 a clinically relevant immune modulator?

METHODS

The study sample was derived from the population of patients presenting to the Massachusetts General Hospital for evaluation and management of giant cell lesions from 1993 to 2008. We included patients with histologically confirmed giant cell lesions with a minimum followup of 6 months. Patients with systemic diseases (n = 4 [3%]), syndromes associated with giant cell lesions (n = 4 [3%]), and those without sufficient followup (n = 26 [19%]), inadequate records (n = 7 [5%]), or inadequate tissue available (n = 2 [1%]) were excluded. Tissue microarray, containing 288 tissue cores for 93 patients, was carefully constructed. This contained tissue from 45 patients with maxillofacial lesions, 38 with aggressive and seven with nonaggressive lesions, and 48 patients with axial and appendicular lesions, 30 with aggressive lesions and 18 with nonaggressive lesions. The population mean age was 28 ± 12 years and the duration of followup was 4 ± 3 years. The tissue microarray was immunohistochemically stained with monoclonal antibodies specific for HLA classes I and II and B7-H3 antigens and analyzed for tumor infiltrating lymphocytes. Antigen expression was examined in multinucleated giant cells and mononuclear stromal cells. The results were correlated with local invasion and tumor aggressiveness, which is based on accepted staging criteria.

RESULTS

Tumor infiltrating lymphocytes were detected in all the tumors. The mean number of CD8+ T cell infiltration was lower in aggressive tumors (median, 4.8; interquartile range [IQR], 0.4-13.4), when compared with nonaggressive tumors (median, 15.8; IQR, 4.3-46.3; p = 0.007). HLA class I antigens were highly expressed by multinucleated giant cells in all tumors, but were lightly expressed on mononuclear stromal cells in 53% (45 of 84) to 73% (56 of 77) of tumors. HLA class I antigen low expression in mononuclear stromal cells was associated with tumor aggressiveness (odds ratio [OR], 4.3; p = 0.005). Low HLA class I expression combined with low CD8+ T cell infiltration was most highly associated with tumor aggressiveness (OR, 7.81; p = 0.011). B7-H3 antigen was expressed in 36.9% mononuclear stroma cells and also was associated with local tumor invasion (OR, 1.36; p < 0.001). Similarly, giant cell lesions with high B7-H3 expression and low CD8+ tumor infiltrating lymphocytes were associated with increased tumor aggressiveness (OR, 8.89; p = 0.0491).

CONCLUSIONS

Locally aggressive giant cell lesions are associated with low HLA class 1 antigen expression, low CD8+T cell infiltration, and high expression of the immune modulator B7-H3.

CLINICAL RELEVANCE

Failure of immune surveillance implies that there may be an opportunity to target aspects of the immune surveillance machinery to treat giant cell lesions.

Tumor cell-associated immune checkpoint molecules - Drivers of malignancy and stemness

Inhibitory or stimulatory immune checkpoint molecules are expressed on a sizeable fraction of tumor cells in different tumor types. It was thought that the main function of tumor cell-associated immune checkpoint molecules would be the modulation (down- or upregulation) of antitumor immune responses. In recent years, however, it has become clear that the expression of immune checkpoint molecules on tumor cells has important consequences on the biology of the tumor cells themselves. In particular, a causal relationship between the expression of these molecules and the acquisition of malignant traits has been demonstrated. Thus, immune checkpoint molecules have been shown to promote the epithelial-mesenchymal transition of tumor cells, the acquisition of tumor-initiating potential and resistance to apoptosis and antitumor drugs, as well as the propensity to disseminate and metastasize. Herein, we review this evidence, with a main focus on PD-L1, the most intensively investigated tumor cell-associated immune checkpoint molecule and for which most information is available. Then, we discuss more concisely other tumor cell-associated immune checkpoint molecules that have also been shown to induce the acquisition of malignant traits, such as PD-1, B7-H3, B7-H4, Tim-3, CD70, CD28, CD137, CD40 and CD47. Open questions in this field as well as some therapeutic approaches that can be derived from this knowledge, are also addressed.

Emerging targets in cancer immunotherapy

The first generation of immune checkpoint inhibitors (anti-CTLA-4 and anti-PD-1/PD-L1) targeted natural immune homeostasis pathways, co-opted by cancers, to drive anti-tumor immune responses. These agents led to unprecedented results in patients with previously incurable metastatic disease and may become first-line therapies for some advanced cancers. However, these agents are efficacious in only a minority of patients. Newer strategies are becoming available that target additional immunomodulatory mechanisms to activate patients' own anti-tumor immune responses. Herein, we present a succinct summary of emerging immune targets with reported pre-clinical efficacy that have progressed to active investigation in clinical trials. These emerging targets include co-inhibitory and co-stimulatory markers of the innate and adaptive immune system. In this review, we discuss: 1) T lymphocyte markers: Lymphocyte Activation Gene 3 [LAG-3], T-cell Immunoglobulin- and Mucin-domain-containing molecule 3 [TIM-3], V-domain containing Ig Suppressor of T cell Activation [VISTA], T cell ImmunoGlobulin and ITIM domain [TIGIT], B7-H3, Inducible T-cell Co-stimulator [ICOS/ICOS-L], CD27/CD70, and Glucocorticoid-Induced TNF Receptor [GITR]; 2) macrophage markers: CD47/Signal-Regulatory Protein alpha [SIRPα] and Indoleamine-2,3-Dioxygenase [IDO]; and 3) natural killer cell markers: CD94/NKG2A and the Killer Immunoglobulin-like receptor [KIR] family. Finally, we briefly highlight combination strategies and potential biomarkers of response and resistance to these cancer immunotherapies.

Immunoregulatory protein B7-H3 promotes growth and decreases sensitivity to therapy in metastatic melanoma cells

B7-H3 (CD276) belongs to the B7 family of immunoregulatory proteins and has been implicated in cancer progression and metastasis. In this study, we found that metastatic melanoma cells with knockdown expression of B7-H3 showed modest decrease in proliferation and glycolytic capacity and were more sensitive to dacarbazine (DTIC) chemotherapy and small-molecule inhibitors targeting MAP kinase (MAPK) and AKT/mTOR pathways: vemurafenib (PLX4032; BRAF inhibitor), binimetinib (MEK-162; MEK inhibitor), everolimus (RAD001; mTOR inhibitor), and triciribidine (API-2; AKT inhibitor). Similar effects were observed in melanoma cells in the presence of an inhibitory B7-H3 monoclonal antibody, while the opposite was seen in B7-H3-overexpressing cells. Further, combining B7-H3 inhibition with small-molecule inhibitors resulted in significantly increased antiproliferative effect in melanoma cells, as well as in BRAF^V600E mutated cell lines derived from patient biopsies. Our findings indicate that targeting B7-H3 may be a novel alternative to improve current therapy of metastatic melanoma.