Dual targeting of CTLA-4 and CD47 on Treg cells promotes immunity against solid tumors

T cell interactions with microglia in immune-inflammatory processes of ischemic stroke

The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke, which promotes neuronal death and inhibits nerve tissue regeneration. As the first immune cells to be activated after an ischemic stroke, microglia play an important immunomodulatory role in the progression of the condition. After an ischemic stroke, peripheral blood immune cells (mainly T cells) are recruited to the central nervous system by chemokines secreted by immune cells in the brain, where they interact with central nervous system cells (mainly microglia) to trigger a secondary neuroimmune response. This review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic stroke. We found that, during ischemic stroke, T cells and microglia demonstrate a more pronounced synergistic effect. Th1, Th17, and M1 microglia can co-secrete pro-inflammatory factors, such as interferon-γ, tumor necrosis factor-α, and interleukin-1β, to promote neuroinflammation and exacerbate brain injury. Th2, Treg, and M2 microglia jointly secrete anti-inflammatory factors, such as interleukin-4, interleukin-10, and transforming growth factor-β, to inhibit the progression of neuroinflammation, as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain injury. Immune interactions between microglia and T cells influence the direction of the subsequent neuroinflammation, which in turn determines the prognosis of ischemic stroke patients. Clinical trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic stroke. However, such studies have been relatively infrequent, and clinical experience is still insufficient. In summary, in ischemic stroke, T cell subsets and activated microglia act synergistically to regulate inflammatory progression, mainly by secreting inflammatory factors. In the future, a key research direction for ischemic stroke treatment could be rooted in the enhancement of anti-inflammatory factor secretion by promoting the generation of Th2 and Treg cells, along with the activation of M2-type microglia. These approaches may alleviate neuroinflammation and facilitate the repair of neural tissues.

Deciphering the role of CD47 in cancer immunotherapy

BACKGROUND

Immunotherapy has emerged as a novel strategy for cancer treatment following surgery, radiotherapy, and chemotherapy. Immune checkpoint blockade and Chimeric antigen receptor (CAR)-T cell therapies have been successful in clinical trials. Cancer cells evade immune surveillance by hijacking inhibitory pathways via overexpression of checkpoint genes. The Cluster of Differentiation 47 (CD47) has emerged as a crucial checkpoint for cancer immunotherapy by working as a "don't eat me" signal and suppressing innate immune signaling. Furthermore, CD47 is highly expressed in many cancer types to protect cancer cells from phagocytosis via binding to SIRPα on phagocytes. Targeting CD47 by either interrupting the CD47-SIRPα axis or combing with other therapies has been demonstrated as an encouraging therapeutic strategy in cancer immunotherapy. Antibodies and small molecules that target CD47 have been explored in pre- and clinical trials. However, formidable challenges such as the anemia and palate aggregation cannot be avoided because of the wide presentation of CD47 on erythrocytes.

AIM OF VIEW

This review summarizes the current knowledge on the regulation and function of CD47, and provides a new perspective for immunotherapy targeting CD47. It also highlights the clinical progress of targeting CD47 and discusses challenges and potential strategies.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review provides a comprehensive understanding of targeting CD47 in cancer immunotherapy, it also augments the concept of combination immunotherapy strategies by employing both innate and adaptive immune responses.

Predicting CTLA4 expression and prognosis in clear cell renal cell carcinoma using a pathomics signature of histopathological images and machine learning

Background

CTLA4, an immune checkpoint, plays an important role in tumor immunotherapy. The purpose of this study was to develop a pathomics signature to evaluate CTLA4 expression and predict clinical outcomes in clear cell renal cell carcinoma (ccRCC) patients.

Methods

A total of 354 patients from the TCGA-KIRC dataset were enrolled in this study. The patients were stratified into two groups based on the level of CTLA4 expression, and overall survival rates were analyzed between groups. Pathological features were identified using machine learning algorithms, and a gradient boosting machine (GBM) was employed to construct the pathomics signatures for predicting prognosis and CTLA4 expression. The predictive performance of the model was subsequently assessed. Enrichment analysis was performed on diferentially expressed genes related to the pathomics score (PS). Additionally, correlations between PS and TMB, as well as immune infiltration profiles associated with different PS values, were explored. In vitro experiments, CTLA4 knockdown was performed to investigate its impact on cell proliferation, migration, invasion, TGF-β signaling pathway, and macrophage polarization.

Results

High expression of CTLA4 was associated with an unfavorable prognosis in ccRCC patients. The pathomics signature displayed good performance in the validation set (AUC = 0.737; P < 0.001 in the log-rank test). The PS was positively correlated with CTLA4 expression. We next explored the underlying mechanism and found the associations between the pathomics signature and TGF-β signaling pathways, TMB, and Tregs. Further in vitro experiments demonstrated that CTLA4 knockdown inhibited cell proliferation, migration, invasion, TGF-β expression, and macrophage M2 polarization.

Conclusion

High expression of CTLA4 was found to correlate with poor prognosis in ccRCC patients. The pathomics signature established by our group using machine learning effectively predicted both patient prognosis and CTLA4 expression levels in ccRCC cases.

Current Landscape of Cancer Immunotherapy: Harnessing the Immune Arsenal to Overcome Immune Evasion

Cancer immune evasion represents a leading hallmark of cancer, posing a significant obstacle to the development of successful anticancer therapies. However, the landscape of cancer treatment has significantly evolved, transitioning into the era of immunotherapy from conventional methods such as surgical resection, radiotherapy, chemotherapy, and targeted drug therapy. Immunotherapy has emerged as a pivotal component in cancer treatment, harnessing the body's immune system to combat cancer and offering improved prognostic outcomes for numerous patients. The remarkable success of immunotherapy has spurred significant efforts to enhance the clinical efficacy of existing agents and strategies. Several immunotherapeutic approaches have received approval for targeted cancer treatments, while others are currently in preclinical and clinical trials. This review explores recent progress in unraveling the mechanisms of cancer immune evasion and evaluates the clinical effectiveness of diverse immunotherapy strategies, including cancer vaccines, adoptive cell therapy, and antibody-based treatments. It encompasses both established treatments and those currently under investigation, providing a comprehensive overview of efforts to combat cancer through immunological approaches. Additionally, the article emphasizes the current developments, limitations, and challenges in cancer immunotherapy. Furthermore, by integrating analyses of cancer immunotherapy resistance mechanisms and exploring combination strategies and personalized approaches, it offers valuable insights crucial for the development of novel anticancer immunotherapeutic strategies.

Prospects and challenges of CAR-T cell therapy combined with ICIs

Immune checkpoint molecules are a group of molecules expressed on the surface of immune cells that primarily regulate their immune homeostasis. Chimeric antigen receptor (CAR) T cell therapy is an immunotherapeutic technology that realizes tumor-targeted killing by constructing synthetic T cells expressing specific antigens through biotechnology. Currently, CAR-T cell therapy has achieved good efficacy in non-solid tumors, but its treatment of solid tumors has not yielded the desired results. Immune checkpoint inhibitors (ICIs) combined with CAR-T cell therapy is a novel combination therapy with high expectations to defeat solid tumors. This review addresses the challenges and expectations of this combination therapy in the treatment of solid tumors.

The Combination of Anti-CD47 Antibody with CTLA4 Blockade Enhances Anti-Tumor Immunity in Non-Small Cell Lung Cancer via Normalization of Tumor Vasculature and Reprogramming of the Immune Microenvironment

In solid tumors, the formidable anti-tumor impact resulting from blocking the "don't eat me" signal, arising from CD47-SIRPα interaction, is constrained, especially compared to its efficacy in hematopoietic malignancies. Activating macrophage anti-tumor activity not only necessitates the inhibition of the "don't eat me" signal, but also the activation of the "eat me" (pre-phagocyte) signal. Intriguingly, the cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) antibody (Ab) has been identified to stimulate Fc receptor-mediated active phagocytes in the tumor microenvironment, thereby generating "eat me" signals. This study postulates that concurrently targeting CD47 and CTLA4 could intensify the anti-tumor effects by simultaneously blocking the "don't eat me" signal while triggering the "eat me" signal. The experimental data from this investigation confirm that the combined targeting of CD47 and CTLA4 enhances immunity against solid tumors in LLC cell-transplanted tumor-bearing mice. This effect is achieved by reducing myeloid-derived suppressor cell infiltration while increasing the presence of effector memory CD8+ T cells, NK1.1+ CD8+ T cells, and activated natural killer T cells. Meanwhile, combination therapy also alleviated anemia. Mechanistically, the anti-CD47 Ab is shown to upregulate CTLA4 levels in NSCLC cells by regulating Foxp1. Furthermore, targeting CD47 is demonstrated to promote tumor vascular normalization through the heightened infiltration of CD4+ T cells. These findings suggest that the dual targeting of CD47 and CTLA4 exerts anti-tumor effects by orchestrating the "eat me" and "don't eat me" signals, reshaping the immune microenvironment, and fostering tumor vascular normalization. This combined therapeutic approach emerges as a potent strategy for effectively treating solid tumors.

VEGFR affects miR-3200-3p-mediated regulatory T cell senescence in tumour-derived exosomes in non-small cell lung cancer

Numerous studies have demonstrated that regulatory T (Treg) cells play an important role in the tumour microenvironment (TME). The aim of this study was to investigate whether VEGFR2 affects the expression of miR-3200-3p in exosomes secreted by tumour cells, thereby influencing Treg senescence in the TME. The results showed that VEGFR2 expression level was the highest in Calu-1 cells, and after transfection with si-VEGFR2, the exosomes secreted from Calu-1 cells were extracted and characterised with no significant difference from the exosomes of the untransfected group, but the expression of miR-3200-3p in the exosomes of the transfected si-VEGFR2 group was elevated. The Cell Counting Kit-8 (CCK-8) and flow cytometry (FCM) results suggested that exosomes highly expressing miR-3200-3p could inhibit Treg cell viability and promote apoptosis levels when treated with Treg cells. Detection of the senescence-associated proteins p16 INK4A and MMP3 by western blot (WB) revealed that exosomes highly expressing miR-3200-3p were able to elevate their protein expression levels. Tumour xenograft experiments demonstrated that exosomes with high miR-3200-3p expression promoted Treg cell senescence and inhibited subcutaneous tumour growth in nude mice. Dual-luciferase reporter assays and RNA pull-down assays showed that miR-3200-3p could be linked with DDB1. Overexpression of DDB1 reverses changes in DCAF1/GSTP1/ROS protein expression caused by exosomes with high miR-3200-3p expression. In conclusion, inhibition of VEGFR2 expression in tumour cells promotes the expression of miR-3200-3p in exosomes secreted by tumour cells. miR-3200-3p enters the TME through exosomes and acts on DDB1 in Treg cells to promote senescence of Treg cells to inhibit tumour progression.

Mechanisms of immune checkpoint inhibitors: insights into the regulation of circular RNAS involved in cancer hallmarks

Current treatment strategies for cancer, especially advanced cancer, are limited and unsatisfactory. One of the most substantial advances in cancer therapy, in the last decades, was the discovery of a new layer of immunotherapy approach, immune checkpoint inhibitors (ICIs), which can specifically activate immune cells by targeting immune checkpoints. Immune checkpoints are a type of immunosuppressive molecules expressed on immune cells, which can regulate the degree of immune activation and avoid autoimmune responses. ICIs, such as anti-PD-1/PD-L1 drugs, has shown inspiring efficacy and broad applicability across various cancers. Unfortunately, not all cancer patients benefit remarkably from ICIs, and the overall response rates to ICIs remain relatively low for most cancer types. Moreover, the primary and acquired resistance to ICIs pose serious challenges to the clinical application of cancer immunotherapy. Thus, a deeper understanding of the molecular biological properties and regulatory mechanisms of immune checkpoints is urgently needed to improve clinical options for current therapies. Recently, circular RNAs (circRNAs) have attracted increasing attention, not only due to their involvement in various aspects of cancer hallmarks, but also for their impact on immune checkpoints in shaping the tumor immune microenvironment. In this review, we systematically summarize the current status of immune checkpoints in cancer and the existing regulatory roles of circRNAs on immune checkpoints. Meanwhile, we also aim to settle the issue in an evidence-oriented manner that circRNAs involved in cancer hallmarks regulate the effects and resistance of ICIs by targeting immune checkpoints.

Research progress and application of single-cell sequencing in head and neck malignant tumors

Single-cell sequencing (SCS) is a technology that separates thousands of cells from the organism and accurately analyzes the genetic material expressed in each cell using high-throughput sequencing technology. Unlike the traditional bulk sequencing approach, which can only provide the average value of a cell population and cannot obtain specific single-cell data, single-cell sequencing can identify the gene sequence and expression changes of a single cell, and reflects the differences between genetic material and protein between cells, and ultimately the role played by the tumor microenvironment. single-cell sequencing can further explore the pathogenesis of head and neck malignancies from the single-cell biological level and provides a theoretical basis for the clinical diagnosis and treatment of head and neck malignancies. This article will systematically introduce the latest progress and application of single-cell sequencing in malignant head and neck tumors.

A Transformable Supramolecular Bispecific Cell Engager for Augmenting Natural Killer and T Cell-Based Cancer Immunotherapy

Immune cells are pivotal in cancer immunotherapy, yet their therapeutic effectiveness is often hampered by limited tumor infiltration and inhibitory tumor microenvironments. An alkaline phosphatase (ALP)-responsive and transformable supramolecular bis-specific cell engager (Supra-BiCE) to harness natural killer (NK)/T cells for effective cancer immunotherapy is introduced here. The Supra-BiCE, consisting of both SA-P (a phosphorylated peptide targeting and blocking programmed cell death ligand 1 (PD-L1)) and SA-T (a phosphorylated peptide targeting and blocking T cell immunoglobulin and ITIM domain (TIGIT)) is constructed by a simple co-assembling strategy. Upon intravenous administration, Supra-BiCE self-assembles into nanoribbons and interacts with NK/T cells via TIGIT. Notably, these nanoribbons undergo transformation into long nanofibrils within ALP-overexpressing tumor regions, resulting in enhanced binding affinities of Supra-BiCE to both PD-L1 and TIGIT. Consequently, this leads to the accumulation and retention of NK/T cells within tumor regions. Furthermore, the combinatorial blockade of checkpoints by Supra-BiCE activates infiltrating NK/T cells. Moreover, the adjustable peptide ratio in Supra-BiCE enables customization for optimal therapeutic effects against distinct tumor types. Particularly, Supra-BiCE (T:P = 1:3) achieved 98.27% tumor suppression rate against colon carcinoma model. Overall, this study offers a promising tool for engaging NK and T cells for cancer immunotherapy.

Recent advances in molecular targeted therapy of lung cancer: Possible application in translation medicine

Lung cancer is one of the leading causes of death among all cancer deaths. This cancer is classified into two different histological subtypes: non-small cell lung cancer (NSCLC), which is the most common subtype, and small cell lung cancer (SCLC), which is the most aggressive subtype. Understanding the molecular characteristics of lung cancer has expanded our knowledge of the cellular origins and molecular pathways affected by each of these subtypes and has contributed to the development of new therapies. Traditional treatments for lung cancer include surgery, chemotherapy, and radiotherapy. Advances in understanding the nature and specificity of lung cancer have led to the development of immunotherapy, which is the newest and most specialized treatment in the treatment of lung cancer. Each of these treatments has advantages and disadvantages and causes side effects. Today, combination therapy for lung cancer reduces side effects and increases the speed of recovery. Despite the significant progress that has been made in the treatment of lung cancer in the last decade, further research into new drugs and combination therapies is needed to extend the clinical benefits and improve outcomes in lung cancer. In this review article, we discussed common lung cancer treatments and their combinations from the most advanced to the newest.

α5-nAChR/STAT3/CD47 axis contributed to nicotine-related lung adenocarcinoma progression and immune escape

OBJECTIVES

The CHRNΑ5 gene, which encodes the α5-nicotinic acetylcholine receptor (α5-nAChR), is related to lung cancer and nicotine addiction. Smoking is closely related to the immunosuppressive effect of macrophages. CD47, a phagocytosis checkpoint in macrophages, is a therapeutic target in various cancer types. Nevertheless, the relationship between α5-nAChR and CD47 in lung cancer is still unclear.

METHODS AND RESULTS

The present study showed that α5-nAChR-mediated CD47 expression via STAT3 signaling, consequently leading to tumor progression and immune suppression in lung adenocarcinoma (LUAD). α5-nAChR expression was correlated with STAT3 expression, CD47 expression, smoking status and poor prognosis of LUAD in vivo. In vitro, α5-nAChR expression mediated the phosphorylation of STAT3, and phosphorylated STAT3 bound to the CD47 promoter and mediated CD47 expression. Downregulation of α5-nAChR and/or CD47 significantly reduced cell proliferation, migration, invasion, stemness and IL-10 expression, but increased TNF-α expression and phagocytosis of macrophages in LUAD. Furthermore, α5-nAChR/CD47 signaling contributed to the growth of subcutaneous xenograft tumors and liver metastasis of tumors in mice.

CONCLUSION

The α5-nAChR/STAT3/CD47 axis contributed to the progression and immune escape of lung cancer and may be a potential target for LUAD immunotherapy.

The antitumor activities of anti-CD47 antibodies require Fc-FcγR interactions

While anti-CD47 antibodies hold promise for cancer immunotherapy, early-phase clinical trials have shown limited clinical benefit, suggesting that CD47 blockade alone might be insufficient for effective tumor control. Here, we investigate the contributions of the Fc domain of anti-CD47 antibodies required for optimal in vivo antitumor activity across multiple species-matched models, providing insights into the mechanisms behind the efficacy of this emerging class of therapeutic antibodies. Using a mouse model humanized for CD47, SIRPα, and FcγRs, we demonstrate that local administration of Fc-engineered anti-CD47 antibodies with enhanced binding to activating FcγRs promotes tumor infiltration of macrophages and antigen-specific T cells, while depleting regulatory T cells. These effects result in improved long-term systemic antitumor immunity and minimal on-target off-tumor toxicity. Our results highlight the importance of Fc optimization in the development of effective anti-CD47 therapies and provide an attractive strategy to enhance the activity of this promising immunotherapy.

Why Treg should be the focus of cancer immunotherapy: The latest thought

Regulatory T cells are a subgroup of T cells with immunomodulatory functions. Different from most cytotoxic T cells and helper T cells, they play a supporting role in the immune system. What's more, regulatory T cells often play an immunosuppressive role, which mainly plays a role in maintaining the stability of the immune system and regulating the immune response in the body. However, recent studies have shown that not only playing a role in autoimmune diseases, organ transplantation, and other aspects, regulatory T cells can also play a role in the immune escape of tumors in the body, through various mechanisms to help tumor cells escape from the demic immune system, weakening the anti-cancer effect in the body. For a better understanding of the role that regulatory T cells can play in cancer, and to be able to use regulatory T cells for tumor immunotherapy more quickly. This review focuses on the research progress of various mechanisms of regulatory T cells in the tumor environment, the related research of tumor cells acting on regulatory T cells, and the existing various therapeutic methods acting on regulatory T cells.

Enhancing anti-tumor immune responses through combination therapies: epigenetic drugs and immune checkpoint inhibitors

Epigenetic mechanisms are processes that affect gene expression and cellular functions without involving changes in the DNA sequence. This abnormal or unstable expression of genes regulated by epigenetics can trigger cancer and other various diseases. The immune cells involved in anti-tumor responses and the immunogenicity of tumors may also be affected by epigenomic changes. This holds significant implications for the development and application of cancer immunotherapy, epigenetic therapy, and their combined treatments in the fight against cancer. We provide an overview of recent research literature focusing on how epigenomic changes in immune cells influence immune cell behavior and function, as well as the immunogenicity of cancer cells. And the combined utilization of epigenetic medications with immune checkpoint inhibitors that focus on immune checkpoint molecules [e.g., Programmed Death 1 (PD-1), Cytotoxic T-Lymphocyte-Associated Protein 4 (CTLA-4), T cell Immunoglobulin and Mucin Domain (TIM-3), Lymphocyte Activation Gene-3 (LAG-3)] present in immune cells and stromal cells associated with tumors. We highlight the potential of small-molecule inhibitors targeting epigenetic regulators to amplify anti-tumor immune responses. Moreover, we discuss how to leverage the intricate relationship between cancer epigenetics and cancer immunology to create treatment regimens that integrate epigenetic therapies with immunotherapies.

The cross-talk between macrophages and tumor cells as a target for cancer treatment

Macrophages represent an important component of the innate immune system. Under physiological conditions, macrophages, which are essential phagocytes, maintain a proinflammatory response and repair damaged tissue. However, these processes are often impaired upon tumorigenesis, in which tumor-associated macrophages (TAMs) protect and support the growth, proliferation, and invasion of tumor cells and promote suppression of antitumor immunity. TAM abundance is closely associated with poor outcome of cancer, with impediment of chemotherapy effectiveness and ultimately a dismal therapy response and inferior overall survival. Thus, cross-talk between cancer cells and TAMs is an important target for immune checkpoint therapies and metabolic interventions, spurring interest in it as a therapeutic vulnerability for both hematological cancers and solid tumors. Furthermore, targeting of this cross-talk has emerged as a promising strategy for cancer treatment with the antibody against CD47 protein, a critical macrophage checkpoint recognized as the "don't eat me" signal, as well as other metabolism-focused strategies. Therapies targeting CD47 constitute an important milestone in the advancement of anticancer research and have had promising effects on not only phagocytosis activation but also innate and adaptive immune system activation, effectively counteracting tumor cells' evasion of therapy as shown in the context of myeloid cancers. Targeting of CD47 signaling is only one of several possibilities to reverse the immunosuppressive and tumor-protective tumor environment with the aim of enhancing the antitumor response. Several preclinical studies identified signaling pathways that regulate the recruitment, polarization, or metabolism of TAMs. In this review, we summarize the current understanding of the role of macrophages in cancer progression and the mechanisms by which they communicate with tumor cells. Additionally, we dissect various therapeutic strategies developed to target macrophage-tumor cell cross-talk, including modulation of macrophage polarization, blockade of signaling pathways, and disruption of physical interactions between leukemia cells and macrophages. Finally, we highlight the challenges associated with tumor hypoxia and acidosis as barriers to effective cancer therapy and discuss opportunities for future research in this field.

Targeting the metabolism of tumor-infiltrating regulatory T cells

Although targeting the tumor metabolism is performed in cooperation with immunotherapy in the era of precision oncology, ignorance of immune cells' metabolism has resulted in unstable antitumor responses. Tumor-infiltrating regulatory T cells (TI-Tregs) are unique, overcoming the hypoxic, acidic, and nutrient-deficient tumor microenvironments (TMEs) and maintaining immunosuppressive functions. However, secondary autoimmunity caused by systemic Treg depletion remains the 'Sword of Damocles' for current Treg-targeted therapies. In this opinion piece, we propose that metabolically reprogrammed TI-Tregs might represent an obstacle to cancer therapies. Indeed, metabolism-based Treg-targeted therapy might provide higher selectivity for clearing TI-Tregs than traditional kinase/checkpoint inhibitors and chemokine/chemokine receptor blockade; it might also restore the efficacy of targeting the tumor metabolism and eliminate certain metabolic barriers to immunotherapy.

The Antitumor Activities of Anti-CD47 Antibodies Require Fc-FcγR interactions

While anti-CD47 antibodies hold promise for cancer immunotherapy, early phase clinical trials have shown limited signs of clinical benefit, suggesting that blockade of CD47 alone may not be sufficient for effective tumor control. Here, we investigate the contributions of the Fc domain of anti-CD47 antibodies required for optimal in vivo antitumor activity across multiple species-matched models, providing new insights into the mechanisms underlying the efficacy of this emerging class of therapeutic antibodies. Using a novel mouse model humanized for CD47, SIRPα and FcγRs, we demonstrate that local administration of an Fc-engineered anti-CD47 antibody with enhanced binding to activating FcγRs modulates myeloid and T-cell subsets in the tumor microenvironment, resulting in improved long-term systemic antitumor immunity and minimal on-target off-tumor toxicity. Our results highlight the importance of Fc optimization in the development of effective anti-CD47 therapies and provide a novel approach for enhancing the antitumor activity of this promising immunotherapy.

Precision Delivery of Dual Immune Inhibitors Loaded Nanomodulator to Reverse Immune Suppression for Combinational Photothermal-Immunotherapy

Although photothermal therapy (PTT) can noninvasively kill tumor cells and exert synergistic immunological effects, the immune responses are usually harmed due to the lack of cytotoxic T cells (CTLs) pre-infiltration and co-existing of intricate immunosuppressive tumor microenvironment (TME), including the programmed cell death ligand 1 (PD-L1)/cluster of differentiation 47 (CD47)/regulatory T cells (Tregs)/M2-macrophages overexpression. Indoleamine 2, 3-dioxygenase inhibitor (NLG919) or bromodomain extra-terminal inhibitor (OTX015) holds great promise to reprogram suppressive TME through different pathways, but their collaborative application remains a formidable challenge because of the poor water solubility and low tumor targeting. To address this challenge, a desirable nanomodulator based on dual immune inhibitors loaded mesoporous polydopamine nanoparticles is designed. This nanomodulator exhibits excellent biocompatibility and water solubility, PTT, and bimodal magnetic resonance/photoacoustic imaging abilities. Owing to enhanced permeability and retention effect and tumor acidic pH-responsiveness, both inhibitors are precisely delivered and locally released at tumor sites. Such a nanomodulator significantly reverses the immune suppression of PD-L1/CD47/Tregs, promotes the activation of CTLs, regulates M2-macrophages polarization, and further boosts combined therapeutic efficacy, inducing a strong immunological memory. Taken together, the nanomodulator provides a practical approach for combinational photothermal-immunotherapy, which may be further broadened to other "immune cold" tumors.

HX009, a novel BsAb dual targeting PD1 x CD47, demonstrates potent anti-lymphoma activity in preclinical models

Both PD1/PD-L1 and CD47 blockades have demonstrated limited activity in most subtypes of NHL save NK/T-cell lymphoma. The hemotoxicity with anti-CD47 agents in the clinic has been speculated to account for their limitations. Herein we describe a first-in-class and rationally designed bispecific antibody (BsAb), HX009, targeting PD1 and CD47 but with weakened CD47 binding, which selectively hones the BsAb for tumor microenvironment through PD1 interaction, potentially reducing toxicity. In vitro characterization confirmed: (1) Both receptor binding/ligand blockade, with lowered CD47 affinity; (2) functional PD1/CD47 blockades by reporter assays; (3) T-cell activation in Staphylococcal-enterotoxin-B-pretreated PBMC and mixed-lymphocyte-reaction. In vivo modeling demonstrated antitumor activity in Raji-B and Karpass-229-T xenograft lymphomas. In the humanized mouse syngeneic A20 B-lymphoma (huCD47-A20) HuGEMM model, which has quadruple knocked-in hPD1xhPD-L1xhCD47xhSIRPα genes and an intact autologous immune-system, a contribution of effect is demonstrated for each targeted biologic (HX008 targeting PD1 and SIRPα-Fc targeting CD47), which is clearly augmented by the dual targeting with HX009. Lastly, the expression of the immune-checkpoints PD-L1/L2 and CD47 seemed co-regulated among a panel of lymphoma-derived-xenografts, where HX009 maybe more effective in those with upregulated CD47. Our data warrants HX009's further clinical development for treating NHLs.

Significance of regulatory T cells in cancer immunology and immunotherapy

Immunosuppression in the tumour microenvironment (TME) attenuates antitumor immunity, consequently hindering protective immunosurveillance and preventing effective antitumor immunity induced by cancer immunotherapy. Multiple mechanisms including immune checkpoint molecules, such as CTLA-4, PD-1, and LAG-3, and immunosuppressive cells are involved in the immunosuppression in the TME. Regulatory T (Treg) cells, a population of immunosuppressive cells, play an important role in inhibiting antitumor immunity. Therefore, Treg cells in the TME correlate with an unfavourable prognosis in various cancer types. Thus, Treg cell is considered to become a promising target for cancer immunotherapy. Elucidating Treg cell functions in cancer patients is therefore crucial for developing optimal Treg cell-targeted immunotherapy. Here, we describe Treg cell functions and phenotypes in the TME from the perspective of Treg cell-targeted immunotherapy.

Targeting tumor microenvironment for non-small cell lung cancer immunotherapy

The tumor microenvironment (TME) is composed of different cellular and non-cellular elements. Constant interactions between tumor cells and the TME are responsible for tumor initiation, tumor progression, and responses to therapies. Immune cells in the TME can be classified into two broad categories, namely adaptive and innate immunity. Targeting these immune cells has attracted substantial research and clinical interest. Current research focuses on identifying key molecular players and developing targeted therapies. These approaches may offer more efficient ways of treating different cancers. In this review, we explore the heterogeneity of the TME in non-small cell lung cancer, summarize progress made in targeting the TME in preclinical and clinical studies, discuss the potential predictive value of the TME in immunotherapy, and highlight the promising effects of bispecific antibodies in the era of immunotherapy.

Targets of Immune Escape Mechanisms in Cancer: Basis for Development and Evolution of Cancer Immune Checkpoint Inhibitors

Immune checkpoint blockade (ICB) has emerged as a novel therapeutic tool for cancer therapy in the last decade. Unfortunately, a small number of patients benefit from approved immune checkpoint inhibitors (ICIs). Therefore, multiple studies are being conducted to find new ICIs and combination strategies to improve the current ICIs. In this review, we discuss some approved immune checkpoints, such as PD-L1, PD-1, and CTLA-4, and also highlight newer emerging ICIs. For instance, HLA-E, overexpressed by tumor cells, represents an immune-suppressive feature by binding CD94/NKG2A, on NK and T cells. NKG2A blockade recruits CD8+ T cells and activates NK cells to decrease the tumor burden. NKG2D acts as an NK cell activating receptor that can also be a potential ICI. The adenosine A2A and A2B receptors, CD47-SIRPα, TIM-3, LAG-3, TIGIT, and VISTA are targets that also contribute to cancer immunoresistance and have been considered for clinical trials. Their antitumor immunosuppressive functions can be used to develop blocking antibodies. PARPs, mARTs, and B7-H3 are also other potential targets for immunosuppression. Additionally, miRNA, mRNA, and CRISPR-Cas9-mediated immunotherapeutic approaches are being investigated with great interest. Pre-clinical and clinical studies project these targets as potential immunotherapeutic candidates in different cancer types for their robust antitumor modulation.

Targeting macrophages: a novel treatment strategy in solid tumors

In the tumor microenvironment (TME), tumor-associated macrophages (TAMs) are the most abundant immune cells, which act as a key regulator in tumorigenesis and progression. Increasing evidence have demonstrated that the TME alters the nature of macrophages to maintain dynamic tissue homeostasis, allowing TAMs to acquire the ability to stimulate angiogenesis, promote tumor metastasis and recurrence, and suppress anti-tumor immune responses. Furthermore, tumors with high TAM infiltration have poor prognoses and are resistant to treatment. In the field of solid tumor, the exploration of tumor-promoting mechanisms of TAMs has attracted much attention and targeting TAMs has emerged as a promising immunotherapeutic strategy. Currently, the most common therapeutic options for targeting TAMs are as follows: the deletion of TAMs, the inhibition of TAMs recruitment, the release of phagocytosis by TAMs, and the reprogramming of macrophages to remodel their anti-tumor capacity. Promisingly, the study of chimeric antigen receptor macrophages (CAR-Ms) may provide even greater benefit for patients with solid tumors. In this review, we discuss how TAMs promote the progression of solid tumors as well as summarize emerging immunotherapeutic strategies that targeting macrophages.

Immunological conversion of solid tumours using a bispecific nanobioconjugate for cancer immunotherapy

Solid tumours display a limited response to immunotherapies. By contrast, haematological malignancies exhibit significantly higher response rates to immunotherapies as compared with solid tumours. Among several microenvironmental and biological disparities, the differential expression of unique immune regulatory molecules contributes significantly to the interaction of blood cancer cells with immune cells. The self-ligand receptor of the signalling lymphocytic activation molecule family member 7 (SLAMF7), a molecule that is critical in promoting the body's innate immune cells to detect and engulf cancer cells, is expressed nearly exclusively on the cell surface of haematologic tumours, but not on solid ones. Here we show that a bispecific nanobioconjugate that enables the decoration of SLAMF7 on the surface of solid tumours induces robust phagocytosis and activates the phagocyte cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway, sensitizing the tumours to immune checkpoint blockade. Our findings support an immunological conversion strategy that uses nano-adjuvants to improve the effectiveness of immunotherapies for solid tumours.

Building on the backbone of CD47-based therapy in cancer: Combination strategies, mechanisms, and future perspectives

Described as a "don't eat me" signal, CD47 becomes a vital immune checkpoint in cancer. Its interaction with signal regulatory protein alpha (SIRPα) prevents macrophage phagocytosis. In recent years, a growing body of evidences have unveiled that CD47-based combination therapy exhibits a superior anti-cancer effect. Latest clinical trials about CD47 have adopted the regimen of collaborating with other therapies or developing CD47-directed bispecific antibodies, indicating the combination strategy as a general trend of the future. In this review, clinical and preclinical cases about the current combination strategies targeting CD47 are collected, their underlying mechanisms of action are discussed, and ideas from future perspectives are shared.

Extracellular Vesicles and Their Roles in the Tumor Immune Microenvironment

Tumor cells actively incorporate molecules (e.g., proteins, lipids, RNA) into particles named extracellular vesicles (EVs). Several groups have demonstrated that EVs can be transferred to target (recipient) cells, making EVs an important means of intercellular communication. Indeed, EVs are able to modulate the functions of target cells by reprogramming signaling pathways. In a cancer context, EVs promote the formation of a supportive tumor microenvironment (TME) and (pre)metastatic niches. Recent studies have revealed that immune cells, tumor cells and their secretome, including EVs, promote changes in the TME and immunosuppressive functions of immune cells (e.g., natural killer, dendritic cells, T and B cells, monocytes, macrophages) that allow tumor cells to establish and propagate. Despite the growing knowledge on EVs and on their roles in cancer and as modulators of the immune response/escape, the translation into clinical practice remains in its early stages, hence requiring improved translational research in the EVs field. Here, we comprehensively review the current knowledge and most recent research on the roles of EVs in tumor immune evasion and immunosuppression in both solid tumors and hematological malignancies. We also highlight the clinical utility of EV-mediated immunosuppression targeting and EV-engineering. Importantly, we discuss the controversial role of EVs in cancer biology, current limitations and future perspectives to further the EV knowledge into clinical practice.

SIRPα-Fc fusion protein IMM01 exhibits dual anti-tumor activities by targeting CD47/SIRPα signal pathway via blocking the “don’t eat me” signal and activating the “eat me” signal

A novel recombinant SIRPα-Fc fusion protein, IMM01, was constructed and produced using an in-house developed CHO-K1 cell expression system, and the anti-tumor mechanism of IMM01 targeting the CD47-SIRPα pathway was explored. The phagocytosis and in vitro anti-tumor activity of IMM01 were evaluated by antibody-dependent cellular phagocytosis (ADCP), antibody-dependent cell-mediated cytotoxicity (ADCC), and complement-dependent cytotoxicity (CDC) assays. In vivo mouse tumor model studies were used to explore therapeutic efficacy as well as the mechanism of action. An in vitro binding assay revealed that IMM01 has a strong binding affinity to CD47 with an EC50 of 0.4967 nM. IMM01 can induce strong ADCP and moderate ADCC, but not CDC. IMM01-induced strong phagocytosis against tumor cells was attributed to dual activities of blocking the "don’t eat me" signal and activating the "eat me" signal, and IMM01 exhibits strong and robust in vivo anti-tumor activities either as monotherapy on hematological malignancies, or in combination therapy with PD-L1 monoclonal antibody (mAb), PD-1 mAb, and HER-2 mAb on solid tumors. Finally, IMM01 demonstrated a favorable safety profile with no human RBC binding activity or hemagglutination induction. IMM01 inhibits the growth of tumor cells by the following three possible mechanisms: (1) directly activating macrophages to phagocytize tumor cells; (2) activated macrophages degrade phagocytized tumor cells and present tumor antigens to T cells through MHC molecules to activate T cells; (3) activated macrophages can convert "cold tumors" into "hot tumors" and increase the infiltration of immune cells through chemotaxis by secreting some cytokines and chemokines.

Oncolytic virus driven T-cell-based combination immunotherapy platform for colorectal cancer

Colorectal cancer is the third most diagnosed cancer and the second leading cause of cancer mortality worldwide, highlighting an urgent need for new therapeutic options and combination strategies for patients. The orchestration of potent T cell responses against human cancers is necessary for effective antitumour immunity. However, regression of a limited number of cancers has been induced by immune checkpoint inhibitors, T cell engagers (TCEs) and/or oncolytic viruses. Although one TCE has been FDA-approved for the treatment of hematological malignancies, many challenges exist for the treatment of solid cancers. Here, we show that TCEs targeting CEACAM5 and CD3 stimulate robust activation of CD4 and CD8-positive T cells in in vitro co-culture models with colorectal cancer cells, but in vivo efficacy is hindered by a lack of TCE retention in the tumour microenvironment and short TCE half-life, as demonstrated by HiBiT bioluminescent TCE-tagging technology. To overcome these limitations, we engineered Bispecific Engager Viruses, or BEVirs, a novel tumour-targeted vaccinia virus platform for intra-tumour delivery of these immunomodulatory molecules. We characterized virus-mediated TCE-secretion, TCE specificity and functionality from infected colorectal cancer cells and patient tumour samples, as well as TCE cytotoxicity in spheroid models, in the presence and absence of T cells. Importantly, we show regression of colorectal tumours in both syngeneic and xenograft mouse models. Our data suggest that a different profile of cytokines may contribute to the pro-inflammatory and immune effects driven by T cells in the tumour microenvironment to provide long-lasting immunity and abscopal effects. We establish combination regimens with immune checkpoint inhibitors for aggressive colorectal peritoneal metastases. We also observe a significant reduction in lung metastases of colorectal tumours through intravenous delivery of our oncolytic virus driven T-cell based combination immunotherapy to target colorectal tumours and FAP-positive stromal cells or CTLA4-positive Treg cells in the tumour microenvironment. In summary, we devised a novel combination strategy for the treatment of colorectal cancers using oncolytic vaccinia virus to enhance immune-payload delivery and boost T cell responses within tumours.

Targeting CD47 as a Novel Immunotherapy for Breast Cancer

Nowadays, breast cancer has become the most common cancer worldwide with a high mortality rate. Immune checkpoint blockade holds great promise in tumor‐targeted therapy, and CD47 blockade as one immune therapy is undergoing various preclinical studies and clinical trials to demonstrate its safety and efficacy in breast cancer. In this review, we summarized different therapeutic mechanisms targeting CD47 and its prognostic role and therapeutic value in breast cancer.

Role of CD47 in tumor immunity: a potential target for combination therapy

CD47 performs a vital function in cancer therapy by binding to different SIRPα, thrombospondin 1, and integrin. However, its role in tumor immunity and its correlation with prognosis among many cancer types remain unknown. The raw mRNA expression data of CD47 in cancer patients was downloaded from TCGA and GTEx datasets. The protein expression of CD47 was detected using a microarray. Kaplan Meier analysis and forest plot were performed to compare the effects of high and low expression of CD47 on overall survival in different cancers. In addition, the correlations between CD47 expression and immune cell infiltration, stromal components, immune checkpoint genes, tumor mutational burden (TMB), and microsatellite instability (MSI) were analyzed from the public database. The gene function was determined by Gene Set Enrichment Analysis (GSEA). The expressions of CD47 in CHOL, COAD, ESCA, HNSC, KIRC, STAD, and THCA were higher compared with normal tissues. Elevated expression of CD47 predicted poor prognosis in ACC, KICH, KIRP, LGG, PAAD and UCEC. CD47 expression was strongly associated with immune infiltrating cells among KICH, KIRP, LGG, and PAAD. In addition, significant positive correlations with most immune checkpoint genes including PDCD 1 (PD-1), CD274 (PD-L1), CTLA4 in BLCA, DLBC, KICH, KIRC, LUAD, LUSC, PAAD, PCPG, SKCM, STAD, UCEC, and UVM was noted for the expression of CD47. GSEA analysis demonstrated that CD47 was a key regulator in metabolism-related pathways. These findings provide novel evidence that CD47 could be utilized as a promising prognostic biomarker and combination treatment target in various cancers.

Neoadjuvant Immunotherapy in Gastrointestinal Cancers - The New Standard of Care?

The development of immune checkpoint inhibitors (ICI) offers novel treatment possibilities for solid cancers, with the crucial benefit of providing higher cure rates. These agents have become part of standard treatments in the metastatic and adjuvant setting for select cancers, such as melanoma, non-small cell lung cancer (NSCLC) or urological malignancies. Currently, there is ample clinical interest in employing ICI in a neoadjuvant setting with a curative intent. This approach is especially supported by the scientific rationale that ICI primarily stimulate the host immune system to eradicate tumor cells, rather than being inherently cytotoxic. Aside from tumor downstaging, neoadjuvant immunotherapy offers the potential of an in situ cancer vaccination, leading to a systemic adjuvant immunological effect after tumor resection. Moreover, preclinical data clearly demonstrate a synergistic effect of ICI with radiotherapy (RT), chemoradiotherapy (CRT) or chemotherapy (ChT). This review harmonizes preclinical concepts with real world data (RWD) in the field of neoadjuvant ICI in gastrointestinal (GI) cancers and discusses their limitations. We believe this is a crucial approach, since up to now, neoadjuvant strategies have been primarily developed by clinicians, whereas the advances in immunotherapy primarily originate from preclinical research. Currently there is limited published data on neoadjuvant ICI in GI cancers, even though neoadjuvant treatments including RT, CRT or ChT are frequently employed in locally advanced/oligometastatic GI cancers (i.e. rectal, pancreatic, esophagus, stomach, etc.). Utilizing established therapies in combination with ICI provides an abundance of opportunities for innovative treatment regimens to further improve survival rates.

Therapeutic strategies targeting uPAR potentiate anti-PD-1 efficacy in diffuse-type gastric cancer

The diffuse-type gastric cancer (DGC) is a subtype of gastric cancer (GC) associated with low HER2 positivity rate and insensitivity to chemotherapy and immune checkpoint inhibitors. Here, we identify urokinase-type plasminogen activator receptor (uPAR) as a potential therapeutic target for DGC. We have developed a novel anti-uPAR monoclonal antibody, which targets the domains II and III of uPAR and blocks the binding of urokinase-type plasminogen activator to uPAR. We show that the combination of anti-uPAR and anti-Programmed cell death protein 1 (PD-1) remarkably inhibits tumor growth and prolongs survival via multiple mechanisms, using cell line-derived xenograft and patient-derived xenograft mouse models. Furthermore, uPAR chimeric antigen receptor-expressing T cells based on the novel anti-uPAR effectively kill DGC patient-derived organoids and exhibit impressive survival benefit in the established mouse models, especially when combined with PD-1 blockade therapy. Our study provides a new possibility of DGC treatment by targeting uPAR in a unique manner.

Immunosuppressive cells in cancer: mechanisms and potential therapeutic targets

Immunotherapies like the adoptive transfer of gene-engineered T cells and immune checkpoint inhibitors are novel therapeutic modalities for advanced cancers. However, some patients are refractory or resistant to these therapies, and the mechanisms underlying tumor immune resistance have not been fully elucidated. Immunosuppressive cells such as myeloid-derived suppressive cells, tumor-associated macrophages, tumor-associated neutrophils, regulatory T cells (Tregs), and tumor-associated dendritic cells are critical factors correlated with immune resistance. In addition, cytokines and factors secreted by tumor cells or these immunosuppressive cells also mediate the tumor progression and immune escape of cancers. Thus, targeting these immunosuppressive cells and the related signals is the promising therapy to improve the efficacy of immunotherapies and reverse the immune resistance. However, even with certain success in preclinical studies or in some specific types of cancer, large perspectives are unknown for these immunosuppressive cells, and the related therapies have undesirable outcomes for clinical patients. In this review, we comprehensively summarized the phenotype, function, and potential therapeutic targets of these immunosuppressive cells in the tumor microenvironment.

Advances in the study of CD47-based bispecific antibody in cancer immunotherapy

Tumor therapy has entered the era of immunotherapy. Monoclonal antibodies (mAb), immune checkpoint inhibitors, chimeric antigen receptor T-cell (CAR-T), cytokine-induced killer (CIK)，tumor-infiltrating lymphocytes (TIL) and other cellular immunotherapies have become the focus of current research. The CD47/SIRPα target is becoming another popular tumor immunotherapy target following the PDCD1/CD247(PD1/PD-L1) checkpoint inhibitor. In recent years, a large number of CD47/SIRPα mAbs, fusion proteins, and CD47/SIRPα-based bispecific antibodies (BsAbs) are undergoing preclinical and clinical trials and have good curative effects in the treatment of hematological tumors and solid tumors. They bring new vitality and hope for the treatment of patients with advanced tumors. This review summarizes the research progress of CD47/SIRPα-based BsAbs with different targets for tumor treatment. There are 12 and 9 BsAbs in clinical trials and pre-clinical research, respectively. We report on the mechanism of 15 BsAb molecules with different target and analyze the efficacy and safety of preclinical and clinical trials, discuss the issues that may be faced in the development of CD47-based BsAbs, and dual target molecules, and summarize their development prospects. This review provides a reference for the safety and effectiveness of BsAbs in clinical application and in the future development of antibodies.

Addressing the Elephant in the Immunotherapy Room: Effector T-Cell Priming versus Depletion of Regulatory T-Cells by Anti-CTLA-4 Therapy

Cytotoxic T-lymphocyte Associated Protein 4 (CTLA-4) is an immune checkpoint molecule highly expressed on regulatory T-cells (Tregs) that can inhibit the activation of effector T-cells. Anti-CTLA-4 therapy can confer long-lasting clinical benefits in cancer patients as a single agent or in combination with other immunotherapy agents. However, patient response rates to anti-CTLA-4 are relatively low, and a high percentage of patients experience severe immune-related adverse events. Clinical use of anti-CTLA-4 has regained interest in recent years; however, the mechanism(s) of anti-CTLA-4 is not well understood. Although activating T-cells is regarded as the primary anti-tumor mechanism of anti-CTLA-4 therapies, mounting evidence in the literature suggests targeting intra-tumoral Tregs as the primary mechanism of action of these agents. Tregs in the tumor microenvironment can suppress the host anti-tumor immune responses through several cell contact-dependent and -independent mechanisms. Anti-CTLA-4 therapy can enhance the priming of T-cells by blockading CD80/86-CTLA-4 interactions or depleting Tregs through antibody-dependent cellular cytotoxicity and phagocytosis. This review will discuss proposed fundamental mechanisms of anti-CTLA-4 therapy, novel uses of anti-CTLA-4 in cancer treatment and approaches to improve the therapeutic efficacy of anti-CTLA-4.

Selective delivery of low-affinity IL-2 to PD-1+ T cells rejuvenates antitumor immunity with reduced toxicity

PD-1 signaling on T cells is the major pathway that limits T cell immunity, but the efficacy of anti–PD-1 therapy has been limited to a small proportion of patients with advanced cancers. We fortuitously observed that anti–PD-1 therapy depends on IL-2 signaling, which raises the possibility that a lack of IL-2 limits anti–PD-1–induced effector T cell expansion. To selectively deliver IL-2 to PD-1⁺CD8⁺ tumor-infiltrating lymphocytes (TILs), we engineered a low-affinity IL-2 paired with anti–PD-1 (PD-1–laIL-2), which reduced affinity to peripheral Treg cells but enhanced avidity to PD-1⁺CD8⁺ TILs. PD-1–laIL-2 exerted better tumor control and lower toxicity than single or mixed treatments. Mechanistically, PD-1–laIL-2 could effectively expand dysfunctional and tumor-specific CD8⁺ T cells. Furthermore, we discovered that presumably dysfunctional PD-1⁺TIM3⁺ TILs are the dominant tumor-specific T cells responding to PD-1–laIL-2. Collectively, these results highlight that PD-1–laIL-2 can target and reactivate tumor-specific TILs for tumor regression as a unique strategy with stronger efficacy and lower toxicity.

The impact of hypoxia on immune state in cancer

Hypoxia is a known feature of solid tumors and a critical promoter of tumor hallmarks. Hypoxia influences tumor immunity in a way favoring immune evasion and resistance. Extreme hypoxia and aberrant hypoxia-inducible factor-1 (HIF-1) activity in tumor microenvironment (TME) is a drawback for effective immunotherapy. Infiltration and activity of CD8⁺ T cells is reduced in such condition, whereas regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) show high activities. Highly hypoxic TME also impairs maturation and activity of dendritic cell (DCs) and natural killer (NK) cells. In addition, the hypoxic TME positively is linked positively with metabolic changes in cells of immune system. These alterations are indicative of a need for hypoxia modulation as a complementary targeting strategy to go with immune checkpoint inhibitor (ICI) therapy.

Targeting CD47 for cancer immunotherapy

Much progress has been made in targeting CD47 for cancer immunotherapy in solid tumors (ST) and hematological malignancies. We summarized the CD47-related clinical research and analyzed the research trend both in the USA and in China. As of August 28, 2021, there are a total 23 related therapeutic agents with 46 clinical trials in the NCT registry platform. Among these trials, 29 are in ST, 14 in hematological malignancies and 3 in both solid tumor and hematological malignancy. The ST include gastric cancer, head and neck squamous cell carcinoma and leiomyosarcoma, while the hematological malignancies include non-Hodgkin's lymphoma, acute myeloid leukemia, myelodysplastic syndrome, multiple myeloma and chronic myeloid leukemia. Majority of the CD47-related clinical trials are at the early phases, such as 31 at phase I, 14 at phase II and 1 at phase III in the USA and 9, 6, 1, in China, respectively. The targets and spectrums of mechanism of action include 26 with mono-specific and 20 with bi-specific targets in the USA and 13 with mono-specific and 3 with bi-specific targets in China. The new generation CD47 antibodies have demonstrated promising results, and it is highly hopeful that some candidate agents will emerge and make into clinical application to meet the urgent needs of patients.