Targeting CD47/SIRPα as a therapeutic strategy, where we are and where we are headed

Silencing of SIRPα enhances the antitumor efficacy of CAR-M in solid tumors

The potential of macrophage-mediated phagocytosis as a cancer treatment is promising. Blocking the CD47-SIRPα interaction with a CD47-specific antibody significantly enhances macrophage phagocytosis. However, concerns regarding their toxicity to nontumor cells remain substantial. Here, we engineered chimeric antigen receptor macrophages (CAR-Ms) by fusing a humanized single-chain variable fragment with FcγRIIa and integrating short hairpin RNA to silence SIRPα, thereby disrupting the CD47-SIRPα signaling pathway. These modified CAR-shSIRPα-M cells exhibited an M1-like phenotype, superior phagocytic function, substantial cytotoxic effects on HER2-positive tumor cells, and the ability to eliminate patient-derived organoids. In vivo, CAR-M cells significantly inhibited tumor growth and prolonged survival in tumor-bearing mice. Notably, CAR-shSIRPα-M cells enhanced cytotoxic T-cell infiltration into tumors, thereby enhancing the antitumor response in both the humanized immune system mouse model and immunocompetent mice. Mechanistically, SIRPα inhibition activated inflammatory pathways and the cGAS-STING signaling cascade in CAR-M cells, leading to increased production of proinflammatory cytokines, reactive oxygen species, and nitric oxide, thereby enhancing their antitumor effects. These findings underscore the potential of SIRPα inhibition as a novel strategy to increase the antitumor efficacy of CAR-M cells in cancer immunotherapy, particularly against solid tumors.

A comprehensive review of immune checkpoint inhibitors for cancer treatment

Immunology-based therapies are emerging as an effective cancer treatment, using the body's immune system to target tumors. Immune checkpoints, which regulate immune responses to prevent tissue damage and autoimmunity, are often exploited by cancer cells to avoid destruction. The discovery of checkpoint proteins like PD-1/PD-L1 and CTLA-4 was pivotal in developing cancer immunotherapy. Immune checkpoint inhibitors (ICIs) have shown great success, with FDA-approved drugs like PD-1 inhibitors (Nivolumab, Pembrolizumab, Cemiplimab), PD-L1 inhibitors (Atezolizumab, Durvalumab, Avelumab), and CTLA-4 inhibitors (Ipilimumab, Tremelimumab), alongside LAG-3 inhibitor Relatlimab. Research continues on new checkpoints like TIM-3, VISTA, B7-H3, BTLA, and TIGIT. Biomarkers like PDL-1 expression, tumor mutation burden, interferon-γ presence, microbiome composition, and extracellular matrix characteristics play a crucial role in predicting responses to immunotherapy with checkpoint inhibitors. Despite their effectiveness, not all patients experience the same level of benefit, and organ-specific immune-related adverse events (irAEs) such as rash or itching, colitis, diarrhea, hyperthyroidism, and hypothyroidism may occur. Given the rapid advancements in this field and the variability in patient outcomes, there is an urgent need for a comprehensive review that consolidates the latest findings on immune checkpoint inhibitors, covering their clinical status, biomarkers, resistance mechanisms, strategies to overcome resistance, and associated adverse effects. This review aims to fill this gap by providing an analysis of the current clinical status of ICIs, emerging biomarkers, mechanisms of resistance, strategies to enhance therapeutic efficacy, and assessment of adverse effects. This review is crucial to furthering our understanding of ICIs and optimizing their application in cancer therapy.

Emerging advances in defining the molecular and therapeutic landscape of small-cell lung cancer

Small-cell lung cancer (SCLC) has traditionally been considered a recalcitrant cancer with a dismal prognosis, with only modest advances in therapeutic strategies over the past several decades. Comprehensive genomic assessments of SCLC have revealed that most of these tumours harbour deletions of the tumour-suppressor genes TP53 and RB1 but, in contrast to non-small-cell lung cancer, have failed to identify targetable alterations. The expression status of four transcription factors with key roles in SCLC pathogenesis defines distinct molecular subtypes of the disease, potentially enabling specific therapeutic approaches. Overexpression and amplification of MYC paralogues also affect the biology and therapeutic vulnerabilities of SCLC. Several other attractive targets have emerged in the past few years, including inhibitors of DNA-damage-response pathways, epigenetic modifiers, antibody-drug conjugates and chimeric antigen receptor T cells. However, the rapid development of therapeutic resistance and lack of biomarkers for effective selection of patients with SCLC are ongoing challenges. Emerging single-cell RNA sequencing data are providing insights into the plasticity and intratumoural and intertumoural heterogeneity of SCLC that might be associated with therapeutic resistance. In this Review, we provide a comprehensive overview of the latest advances in genomic and transcriptomic characterization of SCLC with a particular focus on opportunities for translation into new therapeutic approaches to improve patient outcomes.

Phagocytosis Checkpoints in Glioblastoma: CD47 and Beyond

Glioblastoma multiforme (GBM) is one of the deadliest human cancers with very limited treatment options available. The malignant behavior of GBM is manifested in a tumor which is highly invasive, resistant to standard cytotoxic chemotherapy, and strongly immunosuppressive. Immune checkpoint inhibitors have recently been introduced in the clinic and have yielded promising results in certain cancers. GBM, however, is largely refractory to these treatments. The immune checkpoint CD47 has recently gained attention as a potential target for intervention as it conveys a "don't eat me" signal to tumor-associated macrophages (TAMs) via the inhibitory SIRP alpha protein. In preclinical models, the administration of anti-CD47 monoclonal antibodies has shown impressive results with GBM and other tumor models. Several well-characterized oncogenic pathways have recently been shown to regulate CD47 expression in GBM cells and glioma stem cells (GSCs) including Epidermal Growth Factor Receptor (EGFR) beta catenin. Other macrophage pathways involved in regulating phagocytosis including TREM2 and glycan binding proteins are discussed as well. Finally, chimeric antigen receptor macrophages (CAR-Ms) could be leveraged for greatly enhancing the phagocytosis of GBM and repolarization of the microenvironment in general. Here, we comprehensively review the mechanisms that regulate the macrophage phagocytosis of GBM cells.

Targeting the CD47/SIRPα pathway in malignancies: recent progress, difficulties and future perspectives

Since its initial report in 2015, CD47 has garnered significant attention as an innate immune checkpoint, raising expectations to become the next "PD-1." The optimistic early stages of clinical development spurred a flurry of licensing deals for CD47-targeted molecules and company mergers or acquisitions for related assets. However, a series of setbacks unfolded recently, starting with the July 2023 announcement of discontinuing the phase 3 ENHANCE study on Magrolimab plus Azacitidine for higher-risk myelodysplastic syndromes (MDS). Subsequently, in August 2023, the termination of the ASPEN-02 program, assessing Evorpacept in combination with Azacitidine in MDS patients, was disclosed due to insufficient improvement compared to Azacitidine alone. These setbacks have cast doubt on the feasibility of targeting CD47 in the industry. In this review, we delve into the challenges of developing CD47-SIRPα-targeted drugs, analyze factors contributing to the mentioned setbacks, discuss future perspectives, and explore potential solutions for enhancing CD47-SIRPα-targeted drug development.

Enhancing immunotherapy efficacy against MHC-I deficient triple-negative breast cancer using LCL161-loaded macrophage membrane-decorated nanoparticles

Current cytotoxic T lymphocyte (CTL) activating immunotherapy requires a major histocompatibility complex I (MHC-I)-mediated presentation of tumor-associated antigens, which malfunctions in around half of patients with triple-negative breast cancer (TNBC). Here, we create a LCL161-loaded macrophage membrane decorated nanoparticle (LMN) for immunotherapy of MHC-I-deficient TNBC. SIRPα on the macrophage membrane helps LMNs recognize CD47-expressing cancer cells for targeted delivery of LCL161, which induces the release of high mobility group protein 1 and proinflammatory cytokines from cancer cells. The released cytokines and high mobility group protein 1 activate antitumor immunity by increasing the intratumoral density of the phagocytic macrophage subtype by 15 times and elevating the intratumoral concentration of CTL lymphotoxin by 4.6 folds. LMNs also block CD47-mediated phagocytosis suppression. LMNs inhibit the growth of MHC-I-deficient TNBC tumors, as well as those resistant to combined therapy of anti-PDL1 antibody and albumin-bound paclitaxel, and prolong the survival of animals, during which process CTLs also play important roles. This macrophage membrane-decorated nanoparticle presents a generalizable platform for increasing macrophage-mediated antitumor immunity for effective immunotherapy of MHC-I-deficient cancers.

Contemporary Approaches to Immunotherapy of Solid Tumors

In recent years, the arrival of the immunotherapy industry has introduced the possibility of providing transformative, durable, and potentially curative outcomes for various forms of malignancies. However, further research has shown that there are a number of issues that significantly reduce the effectiveness of immunotherapy, especially in solid tumors. First of all, these problems are related to the protective mechanisms of the tumor and its microenvironment. Currently, major efforts are focused on overcoming protective mechanisms by using different adoptive cell therapy variants and modifications of genetically engineered constructs. In addition, a complex workforce is required to develop and implement these treatments. To overcome these significant challenges, innovative strategies and approaches are necessary to engineer more powerful variations of immunotherapy with improved antitumor activity and decreased toxicity. In this review, we discuss recent innovations in immunotherapy aimed at improving clinical efficacy in solid tumors, as well as strategies to overcome the limitations of various immunotherapies.

Immunological nanomaterials to combat cancer metastasis

Metastasis causes greater than 90% of cancer-associated deaths, presenting huge challenges for detection and efficient treatment of cancer due to its high heterogeneity and widespread dissemination to various organs. Therefore, it is imperative to combat cancer metastasis, which is the key to achieving complete cancer eradication. Immunotherapy as a systemic approach has shown promising potential to combat metastasis. However, current clinical immunotherapies are not effective for all patients or all types of cancer metastases owing to insufficient immune responses. In recent years, immunological nanomaterials with intrinsic immunogenicity or immunomodulatory agents with efficient loading have been shown to enhance immune responses to eliminate metastasis. In this review, we would like to summarize various types of immunological nanomaterials against metastasis. Moreover, this review will summarize a series of immunological nanomaterial-mediated immunotherapy strategies to combat metastasis, including immunogenic cell death, regulation of chemokines and cytokines, improving the immunosuppressive tumour microenvironment, activation of the STING pathway, enhancing cytotoxic natural killer cell activity, enhancing antigen presentation of dendritic cells, and enhancing chimeric antigen receptor T cell therapy. Furthermore, the synergistic anti-metastasis strategies based on the combinational use of immunotherapy and other therapeutic modalities will also be introduced. In addition, the nanomaterial-mediated imaging techniques (e.g., optical imaging, magnetic resonance imaging, computed tomography, photoacoustic imaging, surface-enhanced Raman scattering, radionuclide imaging, etc.) for detecting metastasis and monitoring anti-metastasis efficacy are also summarized. Finally, the current challenges and future prospects of immunological nanomaterial-based anti-metastasis are also elucidated with the intention to accelerate its clinical translation.

The biological roles of CD47 in ovarian cancer progression

Ovarian cancer is one of the most lethal malignant tumors, characterized by high incidence and poor prognosis. Patients relapse occurred in 65-80% after initial treatment. To date, no effective treatment has been established for these patients. Recently, CD47 has been considered as a promising immunotherapy target. In this paper, we reviewed the biological roles of CD47 in ovarian cancer and summarized the related mechanisms. For most types of cancers, the CD47/Sirpα immune checkpoint has attracted the most attention in immunotherapy. Notably, CD47 monoclonal antibodies and related molecules are promising in the immunotherapy of ovarian cancer, and further research is needed. In the future, new immunotherapy regimens targeting CD47 can be applied to the clinical treatment of ovarian cancer patients.

A Perspective on the CD47-SIRPA Axis in High-Risk Neuroblastoma

Neuroblastoma is a pediatric cancer with significant clinical heterogeneity. Despite extensive efforts, it is still difficult to cure children with high-risk neuroblastoma. Immunotherapy is a promising approach to treat children with this devastating disease. We have previously reported that macrophages are important effector cells in high-risk neuroblastoma. In this perspective article, we discuss the potential function of the macrophage inhibitory receptor SIRPA in the homeostasis of tumor-associated macrophages in high-risk neuroblastoma. The ligand of SIRPA is CD47, known as a "don't eat me" signal, which is highly expressed on cancer cells compared to normal cells. CD47 is expressed on both tumor and stroma cells, whereas SIRPA expression is restricted to macrophages in high-risk neuroblastoma tissues. Notably, high SIRPA expression is associated with better disease outcome. According to the current paradigm, the interaction between CD47 on tumor cells and SIRPA on macrophages leads to the inhibition of tumor phagocytosis. However, data from recent clinical trials have called into question the use of anti-CD47 antibodies for the treatment of adult and pediatric cancers. The restricted expression of SIRPA on macrophages in many tissues argues for targeting SIRPA on macrophages rather than CD47 in CD47/SIRPA blockade therapy. Based on the data available to date, we propose that disruption of the CD47-SIRPA interaction by anti-CD47 antibody would shift the macrophage polarization status from M1 to M2, which is inferred from the 1998 study by Timms et al. In contrast, the anti-SIRPA F(ab')2 lacking Fc binds to SIRPA on the macrophage, mimics the CD47-SIRPA interaction, and thus maintains M1 polarization. Anti-SIRPA F(ab')2 also prevents the binding of CD47 to SIRPA, thereby blocking the "don't eat me" signal. The addition of tumor-opsonizing and macrophage-activating antibodies is expected to enhance active tumor phagocytosis.

Evorpacept-Induced Interference and Application of a Novel Mitigation Agent, Evo-NR, in Pretransfusion Testing

Introduction

Evorpacept is a CD47-blocking agent currently being developed for the treatment of various cancers. Interference by evorpacept in pretransfusion compatibility testing has been reported at limited plasma concentrations. Although various mitigation strategies have been proposed, none are practical. This in vitro study assessed evorpacept-induced interference at extended concentrations and investigated the capability of a novel mitigation agent, Evo-NR.

Methods

Antibody screening tests were performed on evorpacept-spiked plasma with (anti-E and anti-Jka) or without alloantibodies at evorpacept concentrations up to 2,000 μg/mL using manual gel cards and automated analyzers. Evorpacept-coated red blood cells (RBCs) (rr [ce/ce], Fy[a+b-], S-s+) were tested by direct antiglobulin testing (DAT) and antigen typing using anti-Fyb and anti-S reagents at indirect antiglobulin testing (IAT) phase. Evo-NR was used to resolve the interference in plasma and RBC samples. Flow cytometry was used to assess the mitigation effects.

Results

Evorpacept-spiked plasma showed panreactive interference in antibody screening tests using manual gel cards (2+ to 3+) and automated analyzers (4+). A carryover effect was also observed in the automated analyzers. The use of a 3- to 6-fold molar excess of Evo-NR effectively resolved the interference in the plasma and enabled accurate alloantibody identification. Although the reduction in evorpacept binding to RBCs was identified via flow cytometry, Evo-NR was incapable of resolving the serologic interference observed in DAT and antigen typing at IAT phase.

Discussion

Evorpacept showed constant panreactivity and a carryover effect at high concentrations. Evo-NR successfully resolved the interference in the plasma samples and could be considered a practical and efficient mitigation solution. Implementation of Evo-NR has the potential to support RBC transfusion for patients undergoing evorpacept treatment.

Progress in cancer research on the regulator of phagocytosis CD47, which determines the fate of tumor cells (Review)

Cluster of differentiation 47 (CD47) is a transmembrane protein that is widely and moderately expressed on the surface of various cells and can have an essential role in mediating cell proliferation, migration, phagocytosis, apoptosis, immune homeostasis and other related responses by binding to its ligands, integrins, thrombospondin-1 and signal regulatory protein α. The poor prognosis of cancer patients is closely associated with high expression of CD47 in glioblastoma, ovarian cancer, breast cancer, bladder cancer, colon cancer and hepatocellular carcinoma. Upregulation of CD47 expression facilitates the growth of numerous types of tumor cells, while downregulation of its expression promotes phagocytosis of tumor cells by macrophages, thereby limiting tumor growth. In addition, blocking CD47 activates the cyclic GMP-AMP (cGAMP) synthase/cGAMP/interferon gene stimulating factor signaling pathway and initiates an adaptive immune response that kills tumor cells. The present review describes the structure, function and interactions of CD47 with its ligands, as well as its regulation of phagocytosis and tumor cell fate. It summarizes the therapeutics, mechanisms of action, research advances and challenges of targeting CD47. In addition, this paper provides an overview of the latest therapeutic options for targeting CD47, such as chimeric antigen receptor (CAR) T-cells, CAR macrophages and nanotechnology-based delivery systems, which are essential for future clinical research on targeting CD47.

Development and evaluation of a human CD47/HER2 bispecific antibody for Trastuzumab-resistant breast cancer immunotherapy

The treatment for trastuzumab-resistant breast cancer (BC) remains a challenge in clinical settings. It was known that CD47 is preferentially upregulated in HER2+ BC cells, which is correlated with drug resistance to trastuzumab. Here, we developed a novel anti-CD47/HER2 bispecific antibody (BsAb) against trastuzumab-resistant BC, named IMM2902. IMM2902 demonstrated high binding affinity, blocking activity, antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and internalization degradation effects against both trastuzumab-sensitive and trastuzumab-resistant BC cells in vitro. The in vivo experimental data indicated that IMM2902 was more effective than their respective controls in inhibiting tumor growth in a trastuzumab-sensitive BT474 mouse model, a trastuzumab-resistant HCC1954 mouse model, two trastuzumab-resistant patient-derived xenograft (PDX) mouse models and a cord blood (CB)-humanized HCC1954 mouse model. Through spatial transcriptome assays, multiplex immunofluorescence (mIFC) and in vitro assays, our findings provided evidence that IMM2902 effectively stimulates macrophages to generate C-X-C motif chemokine ligand (CXCL) 9 and CXCL10, thereby facilitating the recruitment of T cells and NK cells to the tumor site. Moreover, IMM2902 demonstrated a high safety profile regarding anemia and non-specific cytokines release. Collectively, our results highlighted a novel therapeutic approach for the treatment of HER2+ BCs and this approach exhibits significant anti-tumor efficacy without causing off-target toxicity in trastuzumab-resistant BC cells.

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.

Targeting HDAC6 improves anti-CD47 immunotherapy

BACKGROUND

Cancer cells can overexpress CD47, an innate immune checkpoint that prevents phagocytosis upon interaction with signal regulatory protein alpha (SIRPα) expressed in macrophages and other myeloid cells. Several clinical trials have reported that CD47 blockade reduces tumor growth in hematological malignancies. However, CD47 blockade has shown modest results in solid tumors, including melanoma. Our group has demonstrated that histone deacetylase 6 inhibitors (HDAC6is) have immunomodulatory properties, such as controlling macrophage phenotype and inflammatory properties. However, the molecular and cellular mechanisms controlling these processes are not fully understood. In this study, we evaluated the role of HDAC6 in regulating the CD47/SIRPα axis and phagocytosis in macrophages.

METHODS

We tested the role of HDAC6is, especially Nexturastat A, in regulating macrophage phenotype and phagocytic function using bone marrow-derived macrophages and macrophage cell lines. The modulation of the CD47/SIRPα axis and phagocytosis by HDAC6is was investigated using murine and human melanoma cell lines and macrophages. Phagocytosis was evaluated via coculture assays of macrophages and melanoma cells by flow cytometry and immunofluorescence. Lastly, to evaluate the antitumor activity of Nexturastat A in combination with anti-CD47 or anti-SIRPα antibodies, we performed in vivo studies using the SM1 and/or B16F10 melanoma mouse models.

RESULTS

We observed that HDAC6is enhanced the phenotype of antitumoral M1 macrophages while decreasing the protumoral M2 phenotype. In addition, HDAC6 inhibition diminished the expression of SIRPα, increased the expression of other pro-phagocytic signals in macrophages, and downregulated CD47 expression in mouse and human melanoma cells. This regulatory role on the CD47/SIRPα axis translated into enhanced antitumoral phagocytic capacity of macrophages treated with Nexturastat A and anti-CD47. We also observed that the systemic administration of HDAC6i enhanced the in vivo antitumor activity of anti-CD47 blockade in melanoma by modulating macrophage and natural killer cells in the tumor microenvironment. However, Nexturastat A did not enhance the antitumor activity of anti-SIRPα despite its modulation of macrophage populations in the SM1 tumor microenvironment.

CONCLUSIONS

Our results demonstrate the critical regulatory role of HDAC6 in phagocytosis and innate immunity for the first time, further underscoring the use of these inhibitors to potentiate CD47 immune checkpoint blockade therapeutic strategies.

Unfolding the Complexity of Exosome-Cellular Interactions on Tumour Immunity and Their Clinical Prospects in Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy situated in the posterolateral nasopharynx. NPC poses grave concerns in Southeast Asia due to its late diagnosis. Together with resistance to standard treatment combining chemo- and radiotherapy, NPC presents high metastatic rates and common recurrence. Despite advancements in immune-checkpoint inhibitors (ICIs) and cytotoxic-T-lymphocytes (CTLs)-based cellular therapy, the exhaustive T cell profile and other signs of immunosuppression within the NPC tumour microenvironment (TME) remain as concerns to immunotherapy response. Exosomes, extracellular vesicles of 30-150 nm in diameter, are increasingly studied and linked to tumourigenesis in oncology. These bilipid-membrane-bound vesicles are packaged with a variety of signalling molecules, mediating cell-cell communications. Within the TME, exosomes can originate from tumour, immune, or stromal cells. Although there are studies on tumour-derived exosomes (TEX) in NPC and their effects on tumour processes like angiogenesis, metastasis, therapeutic resistance, there is a lack of research on their involvement in immune evasion. In this review, we aim to enhance the comprehension of how NPC TEX contribute to cellular immunosuppression. Furthermore, considering the detectability of TEX in bodily fluids, we will also discuss the potential development of TEX-related biomarkers for liquid biopsy in NPC as this could facilitate early diagnosis and prognostication of the disease.

Targeting TIGIT for cancer immunotherapy: recent advances and future directions

As a newly identified checkpoint, T cell immunoreceptor with immunoglobulin and tyrosine-based inhibitory motif (ITIM) domain (TIGIT) is highly expressed on CD4+ T cells, CD8+ T cells, natural killer (NK) cells, regulatory T cells (Tregs), and tumor-infiltrating lymphocytes (TILs). TIGIT has been associated with NK cell exhaustion in vivo and in individuals with various cancers. It not only modulates NK cell survival but also mediates T cell exhaustion. As the primary ligand of TIGIT in humans, CD155 may be the main target for immunotherapy due to its interaction with TIGIT. It has been found that the anti-programmed cell death protein 1 (PD-1) treatment response in cancer immunotherapy is correlated with CD155 but not TIGIT. Anti-TIGIT alone and in combination with anti-PD-1 agents have been tested for cancer immunotherapy. Although two clinical studies on advanced lung cancer had positive results, the TIGIT-targeted antibody, tiragolumab, recently failed in two new trials. In this review, we highlight the current developments on TIGIT for cancer immunotherapy and discuss the characteristics and functions of TIGIT.

Checkpoint inhibitors

Immune checkpoint inhibitors are a class of antineoplastic therapies that unleash immune cells to kill malignant cells. These medications commonly cause immune-related adverse effects due to activated adaptive and innate immune cells, autoantibody production, and/or cytokine dysregulation. Hematologic toxicities are rare and of uncertain mechanism, and therefore management is often based on experiences with familiar conditions involving these perturbed immune responses. Management is challenging because one must attend to the hematologic toxicity while simultaneously attending to the malignancy, with the imperative that therapeutic effects be maintained or minimally interrupted when possible.

Tumor Immune Cell Targeting Chimeras (TICTACs) For Targeted Depletion of Macrophage-Associated Checkpoint Receptors

Immune cells in the tumor microenvironment are not only powerful regulators of immunosuppression and tumorigenesis, but also represent a dominant cell type, with tumor-associated macrophages (TAMs) comprising up to 50% of total cell mass in solid tumors. Immunotherapies such as immune checkpoint inhibitors (ICIs) derive their efficacy from this cancer-immune cell interface, however, immune-related adverse events resulting from systemic blockade remain a significant challenge. To address this need for potent, yet highly tumor-specific immunotherapies, we developed Tumor-Immune Cell Targeting Chimeras (TICTACs), antibody conjugates that are capable of selectively depleting immune checkpoint receptors such as SIRPa from the surface of TAMs. These chimeric molecules consist of a synthetic glycan ligand that binds the C-type lectin CD206, a well-established TAM marker, conjugated to a non-blocking antibody that binds but does not inhibit the checkpoint receptor. By engaging CD206, which constitutively recycles between the plasma membrane and early endosomes, TICTACs facilitate robust removal of the checkpoint receptors from the surface of CD206high macrophages, while having no effect on CD206low macrophages. By decoupling antibody selectivity from its blocking function, we present a new paradigm for developing highly tumor-specific immunotherapies.

The immunological landscape in pancreatic ductal adenocarcinoma and overcoming resistance to immunotherapy

Pancreatic ductal adenocarcinoma is associated with a poor prognosis and there are few treatment options. The development of immunotherapy in pancreatic ductal adenocarcinoma has been difficult, and immune checkpoint inhibitors are only effective in a very small subset of patients. Most obstacles for treatment have been related to intertumoural and intratumoural heterogeneity, the composition of tumour stroma, and crosstalk with cancer cells. Improved molecular characterisation of pancreatic ductal adenocarcinoma and a better understanding of its microenvironment have paved the way for novel immunotherapy strategies, including the identification of predictive biomarkers, the development of rational combinations to optimise effectiveness, and the targeting of new mechanisms. Future immunotherapy strategies should consider individual characteristics to move beyond the traditional immune targets and circumvent the resistance to therapies that have been developed so far.

Modulating the immune system as a therapeutic target for myelodysplastic syndromes and acute myeloid leukemia

Modulating the immune system to treat diseases, including myeloid malignancies, has resulted in the development of a multitude of novel therapeutics in recent years. Myelodysplastic syndromes or neoplasms (MDS) and acute myeloid leukemia (AML) are hematologic malignancies that arise from defects in hematopoietic stem and progenitor cells (HSPCs). Dysregulated immune responses, especially in innate immune and inflammatory pathways, are highly associated with the acquisition of HSPC defects in MDS and AML pathogenesis. In addition to utilizing the immune system in immunotherapeutic interventions such as chimeric antigen receptor T cell therapy, vaccines, and immune checkpoint inhibitors, mitigating dysregulation of innate immune and inflammatory responses in MDS and AML remains a priority in slowing the initiation and progression of these myeloid malignancies. This review provides a comprehensive summary of the current progress of diverse strategies to utilize or modulate the immune system in the treatment of MDS and AML.

Therapeutic Fusion Proteins

Therapeutic fusion proteins are a class of hybrid constructs that combine distinct biomolecules into a single platform with the additive effects of the components. The ability to fuse two unrelated proteins provides a means to localize mechanisms to better treat a range of diseases. Fusion proteins can be designed to impart diverse functions, including increasing half-life, providing targeting, and enabling sustained signaling. Of these, half-life extenders, which are fused to a therapeutic protein to increase exposure, are the most established group of fusion proteins, with many clinical successes. Rapid advances in antibody and antibody-derivative technology have enabled the fusion of targeting domains with therapeutic proteins. An emerging group of therapeutic fusion proteins has two separate active functions. Although most research for therapeutic fusion proteins focuses on cancer, prior successes provide a foundation for studies into other diseases as well. The exponential emergence of biopharmaceuticals gives precedence for increased research into therapeutic fusion proteins for a multitude of diseases.

Opportunities and challenges of CD47-targeted therapy in cancer immunotherapy

Cancer immunotherapy has emerged as a promising strategy for the treatment of cancer, with the tumor microenvironment (TME) playing a pivotal role in modulating the immune response. CD47, a cell surface protein, has been identified as a crucial regulator of the TME and a potential therapeutic target for cancer therapy. However, the precise functions and implications of CD47 in the TME during immunotherapy for cancer patients remain incompletely understood. This comprehensive review aims to provide an overview of CD47's multifaced role in TME regulation and immune evasion, elucidating its impact on various types of immunotherapy outcomes, including checkpoint inhibitors and CAR T-cell therapy. Notably, CD47-targeted therapies offer a promising avenue for improving cancer treatment outcomes, especially when combined with other immunotherapeutic approaches. The review also discusses current and potential CD47-targeted therapies being explored for cancer treatment and delves into the associated challenges and opportunities inherent in targeting CD47. Despite the demonstrated effectiveness of CD47-targeted therapies, there are potential problems, including unintended effects on healthy cells, hematological toxicities, and the development if resistance. Consequently, further research efforts are warranted to fully understand the underlying mechanisms of resistance and to optimize CD47-targeted therapies through innovative combination approaches, ultimately improving cancer treatment outcomes. Overall, this comprehensive review highlights the significance of CD47 as a promising target for cancer immunotherapy and provides valuable insight into the challenges and opportunities in developing effective CD47-targeted therapies for cancer treatment.

GcForest-based compound-protein interaction prediction model and its application in discovering small-molecule drugs targeting CD47

Identifying compound-protein interaction plays a vital role in drug discovery. Artificial intelligence (AI), especially machine learning (ML) and deep learning (DL) algorithms, are playing increasingly important roles in compound-protein interaction (CPI) prediction. However, ML relies on learning from large sample data. And the CPI for specific target often has a small amount of data available. To overcome the dilemma, we propose a virtual screening model, in which word2vec is used as an embedding tool to generate low-dimensional vectors of SMILES of compounds and amino acid sequences of proteins, and the modified multi-grained cascade forest based gcForest is used as the classifier. This proposed method is capable of constructing a model from raw data, adjusting model complexity according to the scale of datasets, especially for small scale datasets, and is robust with few hyper-parameters and without over-fitting. We found that the proposed model is superior to other CPI prediction models and performs well on the constructed challenging dataset. We finally predicted 2 new inhibitors for clusters of differentiation 47(CD47) which has few known inhibitors. The IC50s of enzyme activities of these 2 new small molecular inhibitors targeting CD47-SIRPα interaction are 3.57 and 4.79 μM respectively. These results fully demonstrate the competence of this concise but efficient tool for CPI prediction.

Design of siRNA Bioconjugates for Efficient Control of Cancer-Associated Membrane Receptors

Research on siRNA delivery has seen tremendous growth over the past few decades. As one of the major delivery strategies, siRNA bioconjugates offer the potential to enhance and extend the pharmacological properties of siRNAs while minimizing toxicity. In this paper, we suggest the development of a siRNA conjugate platform with peptides and proteins that are ligands of target receptors for cancer treatment. The siRNA bioconjugates target and block the receptor membrane proteins, enter the cells through receptor-mediated endocytosis, and inhibit the expression of that same target membrane receptor, thereby doubly controlling the function of the membrane proteins. The three kinds of bioconjugates targeting CD47, PD-L1, and EGFR were synthesized via two different copper-free click chemistry reactions. Results showed the cellular uptake of each conjugate, reduction of target gene expression, and efficient functional control of receptor proteins. This platform provides an effective approach for regulating membrane proteins in various diseases beyond cancer.

New hope for tumor immunotherapy: the macrophage-related "do not eat me" signaling pathway

The "do not eat me" signaling pathway is extremely active in tumor cells, providing a means for these cells to elude macrophage phagocytosis and escape immune surveillance. Representative markers of this pathway, such as CD47 and CD24, are highly expressed in numerous tumors. The interaction of SIRPα with CD47 reduces the accumulation of non-myosin ⅡA on the cell membrane. The combination of CD24 and Siglec10 ultimately leads to the recruitment of SHP-1 or SHP-2 to reduce signal transduction. Both of them weaken the ability of macrophages to engulf tumor cells. Blocking the mutual recognition between CD47-SIRPα or CD24-Siglec10 using large molecular proteins or small molecular drugs represents a promising avenue for tumor immunotherapy. Doing so can inhibit signal transduction and enhance macrophage clearance rates of cancer cells. In this paper, we summarize the characteristics of the drugs that affect the "do not eat me" signaling pathway via classical large molecular proteins and small molecule drugs, which target the CD47-SIRPα and CD24-Siglec10 signaling pathways, which target the CD47-SIRPα and CD24-Siglec10 signaling pathways. We expect it will offer insight into the development of new drugs centered on blocking the "do not eat me" signaling pathway.

Targeting CD47 as a therapeutic strategy: A common bridge in the therapy of COVID-19-related cancers

Macrophages are essential mediators of innate immunity. Non-self-cells resist phagocytosis through the expression of the checkpoint molecule CD47. CD47, as the integrin-associated protein, is overexpressed on tumor and SARS-CoV-2-infected cells as a potential surface biomarker for immune surveillance evasion. CD47-signal-regulating protein alpha (SIRPα) interaction is a promising innate immunotarget. Previous findings based on monoclonal antibodies (mAbs) or fusion proteins that block CD47 or SIRPα have been developed in cancer research. While CD47 efficacy in infectious diseases, especially severe COVID-19 studies, is lacking, focus on macrophage-mediated immunotherapy that increases "eat me" signals in combination therapy with mAbs is optimistic. This integrin-related protein can be as a potential target to therapy for COVID-19. Here, we concentrate on the role of the CD47 signaling pathway as a novel therapeutic strategy for COVID-19-associated cancer treatment.

Molecular Imaging of Innate Immunity and Immunotherapy

The innate immune system plays a key role as the first line of defense in various human diseases including cancer, cardiovascular and inflammatory diseases. In contrast to tissue biopsies and blood biopsies, in vivo imaging of the innate immune system can provide whole body measurements of immune cell location and function and changes in response to disease progression and therapy. Rationally developed molecular imaging strategies can be used in evaluating the status and spatio-temporal distributions of the innate immune cells in near real-time, mapping the biodistribution of novel innate immunotherapies, monitoring their efficacy and potential toxicities, and eventually for stratifying patients that are likely to benefit from these immunotherapies. In this review, we will highlight the current state-of-the-art in noninvasive imaging techniques for preclinical imaging of the innate immune system particularly focusing on cell trafficking, biodistribution, as well as pharmacokinetics and dynamics of promising immunotherapies in cancer and other diseases; discuss the unmet needs and current challenges in integrating imaging modalities and immunology and suggest potential solutions to overcome these barriers.

Changes of tumor microenvironment in non-small cell lung cancer after TKI treatments

Non-small cell lung cancer (NSCLC) is the most common lung cancer diagnosis, among which epidermal growth factor receptor (EGFR), Kirsten rat sarcoma (KRAS), and anaplastic lymphoma kinase (ALK) mutations are the common genetic drivers. Their relative tyrosine kinase inhibitors (TKIs) have shown a better response for oncogene-driven NSCLC than chemotherapy. However, the development of resistance is inevitable following the treatments, which need a new strategy urgently. Although immunotherapy, a hot topic for cancer therapy, has shown an excellent response for other cancers, few responses for oncogene-driven NSCLC have been presented from the existing evidence, including clinical studies. Recently, the tumor microenvironment (TME) is increasingly thought to be a key parameter for the efficacy of cancer treatment such as targeted therapy or immunotherapy, while evidence has also shown that the TME could be affected by multi-factors, such as TKIs. Here, we discuss changes in the TME in NSCLC after TKI treatments, especially for EGFR-TKIs, to offer information for a new therapy of oncogene-driven NSCLC.

Immunotherapies against HER2-Positive Breast Cancer

Breast cancer is the leading cause of cancer-related deaths among women worldwide. HER2-positive breast cancer, which represents 15-20% of all cases, is characterized by the overexpression of the HER2 receptor. Despite the variety of treatments available for HER2-positive breast cancer, both targeted and untargeted, many patients do not respond to therapy and relapse and eventually metastasize, with a poor prognosis. Immunotherapeutic approaches aim to enhance the antitumor immune response to prevent tumor relapse and metastasis. Several immunotherapies have been approved for solid tumors, but their utility for HER2-positive breast cancer has yet to be confirmed. In this review, we examine the different immunotherapeutic strategies being tested in HER2-positive breast cancer, from long-studied cancer vaccines to immune checkpoint blockade, which targets immune checkpoints in both T cells and tumor cells, as well as the promising adoptive cell therapy in various forms. We discuss how some of these new approaches may contribute to the prevention of tumor progression and be used after standard-of-care therapies for resistant HER2-positive breast tumors, highlighting the benefits and drawbacks of each. We conclude that immunotherapy holds great promise for the treatment of HER2-positive tumors, with the potential to completely eradicate tumor cells and prevent the progression of the disease.

Moving toward individualized target-based therapies in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease at the genetic level. The field of AML therapy is increasingly shifting away from uniform approaches based solely on intensive chemotherapy (such as '7 + 3') toward personalized therapy. The treatment of AML can now be individualized based on patient characteristics and cytogenetic/molecular disease features. In this review, we provide a comprehensive updated summary of personalized, target-directed therapy in AML. We first discuss the selection of intensive versus low-intensity treatment approaches based on the patient's age and/or comorbidities. We follow with a detailed review of specific molecularly defined AML subtypes that benefit from the addition of targeted agents. In this context, we highlight the urgent need for novel therapies in tumor protein p53 (TP53)-mutated AML. We then propose approaches to optimize AML therapy in patients without directly actionable mutations. We conclude with a discussion on the emerging role of using measurable residual disease to modify therapy based on the quality of response.

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.

Repurposing of Commercially Existing Molecular Target Therapies to Boost the Clinical Efficacy of Immune Checkpoint Blockade

Immune checkpoint blockade (ICB) is now standard of care for several metastatic epithelial cancers and prolongs life expectancy for a significant fraction of patients. A hostile tumor microenvironment (TME) induced by intrinsic oncogenic signaling induces an immunosuppressive niche that protects the tumor cells, limiting the durability and efficacy of ICB therapies. Addition of receptor tyrosine kinase inhibitors (RTKi) as potential modulators of an unfavorable local immune environment has resulted in moderate life expectancy improvement. Though the combination strategy of ICB and RTKi has shown significantly better results compared to individual treatment, the benefits and adverse events are additive whereas synergy of benefit would be preferable. There is therefore a need to investigate the potential of inhibitors other than RTKs to reduce malignant cell survival while enhancing anti-tumor immunity. In the last five years, preclinical studies have focused on using small molecule inhibitors targeting cell cycle and DNA damage regulators such as CDK4/6, CHK1 and poly ADP ribosyl polymerase (PARP) to selectively kill tumor cells and enhance cytotoxic immune responses. This review provides a comprehensive overview of the available drugs that attenuate immunosuppression and overcome hostile TME that could be used to boost FDA-approved ICB efficacy in the near future.

Accurate treatment of small cell lung cancer: Current progress, new challenges and expectations

Small cell lung cancer (SCLC) is a deadly disease with poor prognosis. Fast growing speed, inclination to metastasis, enrichment in cancer stem cells altogether constitute its aggressive nature. In stark contrast to non-small cell lung cancer (NSCLC) that strides vigorously on the road to precision oncology, SCLC has been on the embryonic path to achieve effective personalized treatments. The survival of patients with SCLC have not been improved greatly, which could be possibly due to our inadequate understanding of genetic alterations of SCLC. Recently, encouraging effects have been observed in patients with SCLC undergoing immunotherapy. However, exciting results have only been observed in a small fraction of patients with SCLC, warranting biomarkers predictive of responses as well as novel therapeutic strategies. In addition, SCLC has previously been viewed to be homogeneous. However, perspectives have been changed thanks to the advances in sequencing techniques and platforms, which unfolds the complex heterogeneity of SCLC both genetically and non-genetically, rendering the treatment of SCLC a further step forward into the precision era. To outline the road of SCLC towards precision oncology, we summarize the progresses and achievements made in precision treatment in SCLC in genomic, transcriptomic, epigenetic, proteomic and metabolic dimensions. Moreover, we conclude relevant therapeutic vulnerabilities in SCLC. Clinically tested drugs and clinical trials have also been demonstrated. Ultimately, we look into the opportunities and challenges ahead to advance the individualized treatment in pursuit of improved survival for patients with SCLC.

Emerging Trends in Immunotherapy for Cancer

Recent advances in cancer immunology have enabled the discovery of promising immunotherapies for various malignancies that have shifted the cancer treatment paradigm. The innovative research and clinical advancements of immunotherapy approaches have prolonged the survival of patients with relapsed or refractory metastatic cancers. Since the U.S. FDA approved the first immune checkpoint inhibitor in 2011, the field of cancer immunotherapy has grown exponentially. Multiple therapeutic approaches or agents to manipulate different aspects of the immune system are currently in development. These include cancer vaccines, adoptive cell therapies (such as CAR-T or NK cell therapy), monoclonal antibodies, cytokine therapies, oncolytic viruses, and inhibitors targeting immune checkpoints that have demonstrated promising clinical efficacy. Multiple immunotherapeutic approaches have been approved for specific cancer treatments, while others are currently in preclinical and clinical trial stages. Given the success of immunotherapy, there has been a tremendous thrust to improve the clinical efficacy of various agents and strategies implemented so far. Here, we present a comprehensive overview of the development and clinical implementation of various immunotherapy approaches currently being used to treat cancer. We also highlight the latest developments, emerging trends, limitations, and future promises of cancer immunotherapy.

Crystal Structure of Human CD47 in Complex with Engineered SIRPα.D1(N80A)

Background: Targeting the CD47/SIRPα signaling pathway represents a novel approach to enhance anti-tumor immunity. However, the crystal structure of the CD47/SIRPα has not been fully studied. This study aims to analyze the structure interface of the complex of CD47 and IMM01, a novel recombinant SIRPα-Fc fusion protein. Methods: IMM01-Fab/CD47 complex was crystalized, and diffraction images were collected. The complex structure was determined by molecular replacement using the program PHASER with the CD47-SIRPαv2 structure (PDB code 2JJT) as a search model. The model was manually built using the COOT program and refined using TLS parameters in REFMAC from the CCP4 program suite. Results: Crystallization and structure determination analysis of the interface of IMM01/CD47 structure demonstrated CD47 surface buried by IMM01. Comparison with the literature structure (PDB ID 2JJT) showed that the interactions of IMM01/CD47 structure are the same. All the hydrogen bonds that appear in the literature structure are also present in the IMM01/CD47 structure. These common hydrogen bonds are stable under different crystal packing styles, suggesting that these hydrogen bonds are important for protein binding. In the structure of human CD47 in complex with human SIRPα, except SER66, the amino acids that form hydrogen bonds are all conserved. Furthermore, comparing with the structure of PDB ID 2JJT, the salt bridge interaction from IMM01/CD47 structure are very similar, except the salt bridge bond between LYS53 in IMM01 and GLU106 in CD47, which only occurs between the B and D chains. However, as the side chain conformation of LYS53 in chain A is slightly different, the salt bridge bond is absent between the A and C chains. At this site between chain A and chain C, there are a salt bridge bond between LYS53 (A) and GLU104 (C) and a salt bridge bond between HIS56 (A) and GLU106 (C) instead. According to the sequence alignment results of SIRPα, SIRPβ and SIRPγ in the literature of PDB ID 2JJT, except ASP100, the amino acids that form common salt bridge bonds are all conserved. Conclusion: Our data demonstrated crystal structure of the IMM01/CD47 complex and provides a structural basis for the structural binding interface and future clinical applications.

Targeting macrophages in hematological malignancies: recent advances and future directions

Emerging evidence indicates that the detection and clearance of cancer cells via phagocytosis induced by innate immune checkpoints play significant roles in tumor-mediated immune escape. The most well-described innate immune checkpoints are the "don't eat me" signals, including the CD47/signal regulatory protein α axis (SIRPα), PD-1/PD-L1 axis, CD24/SIGLEC-10 axis, and MHC-I/LILRB1 axis. Molecules have been developed to block these pathways and enhance the phagocytic activity against tumors. Several clinical studies have investigated the safety and efficacy of CD47 blockades, either alone or in combination with existing therapy in hematological malignancies, including myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and lymphoma. However, only a minority of patients have significant responses to these treatments alone. Combining CD47 blockades with other treatment modalities are in clinical studies, with early results suggesting a synergistic therapeutic effect. Targeting macrophages with bispecific antibodies are being explored in blood cancer therapy. Furthermore, reprogramming of pro-tumor macrophages to anti-tumor macrophages, and CAR macrophages (CAR-M) demonstrate anti-tumor activities. In this review, we elucidated distinct types of macrophage-targeted strategies in hematological malignancies, from preclinical experiments to clinical trials, and outlined potential therapeutic approaches being developed.

Dynamic CD8+ T Cell Cooperation with Macrophages and Monocytes for Successful Cancer Immunotherapy

Simple Summary

Innate and adaptive immunity mutually regulate one another in a dynamic fashion during immune responses. In infectious contexts, positive interactions between macrophages, monocytes and T cells are well recognized, but this is not the case in the field of cancer, where the growth of tumors disturbs the immune response. However, recent advances revealed that successful immunotherapy profoundly remodels the tumor microenvironment, promoting the activation of both T cells and myeloid cells. This review highlights the studies that hint at positive CD8⁺ T cell cooperation with monocytes and macrophages in this context, and discusses the potential mechanisms behind this.

Abstract

The essential roles endorsed by macrophages and monocytes are well established in response to infections, where they contribute to launching the differentiation of specific T-lymphocytes for long-term protection. This knowledge is the result of dynamic studies that can inspire the cancer field, particularly now that cancer immunotherapies elicit some tumor regression. Indeed, immune responses to cancer have mainly been studied after tumors have escaped immune attacks. In particular, the suppressive functions of macrophages were revealed in this context, introducing an obvious bias across the literature. In this review, we will focus on the ways inwhich monocytes and macrophages cooperate with T-lymphocytes, leading to successful immune responses. We will bring together the preclinical studies that have revealed the existence of such positive cooperation in the cancer field, and we will place particular emphasis on proposing the underlying mechanisms. Finally, we will give some perspectives to decipher the functional roles of such T-cell and myeloid cell interactions in the frame of human cancer immunotherapy.