CD22, a B lymphocyte-specific adhesion molecule that regulates antigen receptor signaling

Antibody-drug conjugates in cancer therapy: mechanisms and clinical studies

Antibody-drug conjugates (ADCs) consist of monoclonal antibodies that target tumor cells and cytotoxic drugs linked through linkers. By leveraging antibodies' targeting properties, ADCs deliver cytotoxic drugs into tumor cells via endocytosis after identifying the tumor antigen. This precise method aims to kill tumor cells selectively while minimizing harm to normal cells, offering safe and effective therapeutic benefits. Recent years have seen significant progress in antitumor treatment with ADC development, providing patients with new and potent treatment options. With over 300 ADCs explored for various tumor indications and some already approved for clinical use, challenges such as resistance due to factors like antigen expression, ADC processing, and payload have emerged. This review aims to outline the history of ADC development, their structure, mechanism of action, recent composition advancements, target selection, completed and ongoing clinical trials, resistance mechanisms, and intervention strategies. Additionally, it will delve into the potential of ADCs with novel markers, linkers, payloads, and innovative action mechanisms to enhance cancer treatment options. The evolution of ADCs has also led to the emergence of combination therapy as a new therapeutic approach to improve drug efficacy.

Macrophage senescence in health and diseases

Macrophage senescence, manifested by the special form of durable cell cycle arrest and chronic low-grade inflammation like senescence-associated secretory phenotype, has long been considered harmful. Persistent senescence of macrophages may lead to maladaptation, immune dysfunction, and finally the development of age-related diseases, infections, autoimmune diseases, and malignancies. However, it is a ubiquitous, multi-factorial, and dynamic complex phenomenon that also plays roles in remodeled processes, including wound repair and embryogenesis. In this review, we summarize some general molecular changes and several specific biomarkers during macrophage senescence, which may bring new sight to recognize senescent macrophages in different conditions. Also, we take an in-depth look at the functional changes in senescent macrophages, including metabolism, autophagy, polarization, phagocytosis, antigen presentation, and infiltration or recruitment. Furthermore, some degenerations and diseases associated with senescent macrophages as well as the mechanisms or relevant genetic regulations of senescent macrophages are integrated, not only emphasizing the possibility of regulating macrophage senescence to benefit age-associated diseases but also has an implication on the finding of potential targets or drugs clinically.

N-linked Fc glycosylation is not required for IgG-B-cell receptor function in a GC-derived B-cell line

IgG secreted by B cells carry asparagine N(297)-linked glycans in the fragment crystallizable (Fc) region. Changes in Fc glycosylation are related to health or disease and are functionally relevant, as IgG without Fc glycans cannot bind to Fcɣ receptors or complement factors. However, it is currently unknown whether ɣ-heavy chain (ɣHC) glycans also influence the function of membrane-bound IgG-B-cell receptors (BCR) and thus the outcome of the B-cell immune response. Here, we show in a germinal center (GC)-derived human B-cell line that ɣHC glycans do not affect membrane expression of IgG-BCRs. Furthermore, antigen binding or other BCR-facilitated mechanisms appear unaffected, including BCR downmodulation or BCR-mediated signaling. As expected, secreted IgG lacking Fc glycosylation is unable to carry out effector functions. Together, these observations indicate that IgG-Fc glycosylation serves as a mechanism to control the effector functions of antibodies, but does not regulate the activation of IgG-switched B cells, as its absence had no apparent impact on BCR function.

The Evolving Landscape of Antibody-Drug Conjugates: In Depth Analysis of Recent Research Progress

Antibody-drug conjugates (ADCs) are targeted immunoconjugate constructs that integrate the potency of cytotoxic drugs with the selectivity of monoclonal antibodies, minimizing damage to healthy cells and reducing systemic toxicity. Their design allows for higher doses of the cytotoxic drug to be administered, potentially increasing efficacy. They are currently among the most promising drug classes in oncology, with efforts to expand their application for nononcological indications and in combination therapies. Here we provide a detailed overview of the recent advances in ADC research and consider future directions and challenges in promoting this promising platform to widespread therapeutic use. We examine data from the CAS Content Collection, the largest human-curated collection of published scientific information, and analyze the publication landscape of recent research to reveal the exploration trends in published documents and to provide insights into the scientific advances in the area. We also discuss the evolution of the key concepts in the field, the major technologies, and their development pipelines with company research focuses, disease targets, development stages, and publication and investment trends. A comprehensive concept map has been created based on the documents in the CAS Content Collection. We hope that this report can serve as a useful resource for understanding the current state of knowledge in the field of ADCs and the remaining challenges to fulfill their potential.

CD22 is a potential target of CAR-NK cell therapy for esophageal squamous cell carcinoma

BACKGROUND

Chimeric antigen receptor NK (CAR-NK) cell therapy is one of the most promising immunotherapies. Although it has shown a significant therapeutic effect in hematologic malignancies, few successes have been obtained in solid tumors including esophageal squamous cell carcinoma (ESCC). The major reasons are lack of specific cell surface antigens and complex tumor microenvironment. Here we identify CD22, a well-known tumor surface marker in hematologic malignancies, is expressed in ESCC, possibly serving as a potential target of CAR-NK cell therapy.

METHODS

The expression of 13 tumor cell surface antigens used clinically was analyzed in patients from The Cancer Genome Atlas (TCGA) database. Also, mRNA expression were detected in 2 ESCC cell lines and 2 patients samples by qCPR. Then according to Venn diagram, CD22 was selected for further investigation. Following this, the expression of CD22 by immunofluorescence (IF) in ESCC cell lines and by immunohistochemistry (IHC) in 87 cases of human ESCC samples was detected respectively. On the basis of H-score results, the correlation between CD22 expression and clinical parameters was analyzed. As a proof, the efficacy of CD22-targeted CAR-NK cells against ESCC cell lines was performed by a real-time cell analyzer (RTCA) platform.

RESULTS

KYSE-140 and KYSE-150 cell lines displayed surface expression of CD22. IHC showed an 80.46% (70/87) positive rate in ESCC patient samples. Among these, cell membranous expression of CD22 was observed in 27.59% (24/87) patient samples. Through chi-square test, expression of CD22 in ESCC was associated with lymph node metastasis while it was no related to the depth of tumor invasion and clinical stage. Engineered CD22-targeted CAR-NK cells exhibited inhibitory growth capability against ESCC cell lines (p < 0.0001).

CONCLUSIONS

CD22 is a potential tumor surface antigen capable of being targeted by CAR-NK cells in ESCC. And potential therapeutics for ESCC may be developed based on immune cells expressing anti-CD22 CAR. The study also indicates that CD22 CAR-NK cells could be used in other cancers and more in vivo experiments are needed.

The role of N-glycosylation in B-cell biology and IgG activity. The aspects of autoimmunity and anti-inflammatory therapy

The immune system is strictly regulated by glycosylation through the addition of highly diverse and dynamically changing sugar structures (glycans) to the majority of immune cell receptors. Although knowledge in the field of glycoimmunology is still limited, numerous studies point to the key role of glycosylation in maintaining homeostasis, but also in reflecting its disruption. Changes in oligosaccharide patterns can lead to impairment of both innate and acquired immune responses, with important implications in the pathogenesis of diseases, including autoimmunity. B cells appear to be unique within the immune system, since they exhibit both innate and adaptive immune activity. B cell surface is rich in glycosylated proteins and lectins which recognise glycosylated ligands on other cells. Glycans are important in the development, selection, and maturation of B cells. Changes in sialylation and fucosylation of cell surface proteins affect B cell signal transduction through BCRs, CD22 inhibitory coreceptor and Siglec-G. Plasmocytes, as the final stage of B cell differentiation, produce and secrete immunoglobulins (Igs), of which IgGs are the most abundant N-glycosylated proteins in human serum with the conserved N-glycosylation site at Asn297. N-oligosaccharide composition of the IgG Fc region affects its secretion, structure, half-life and effector functions (ADCC, CDC). IgG N-glycosylation undergoes little change during homeostasis, and may gradually be modified with age and during ongoing inflammatory processes. Hyperactivated B lymphocytes secrete autoreactive antibodies responsible for the development of autoimmunity. The altered profile of IgG N-glycans contributes to disease progression and remission and is sensitive to the application of therapeutic substances and immunosuppressive agents. In this review, we focus on the role of N-glycans in B-cell biology and IgG activity, the rearrangement of IgG oligosaccharides in aging, autoimmunity and immunosuppressive therapy.

Binding domain on CD22 molecules contributing to the biological activity of T cell-engaging bispecific antibodies

CD22, as the B-cell malignancies antigen, has been targeted for immunotherapies through CAR-T cells, antibody-drug conjugates (ADCs) and immunotoxins via interaction of antibodies with binding domains on the receptor. We hypothesized that avidity and binding domain of antibody to target cells may have significant impact on the biological function in tumor immunotherapy, and T cell-engaging bispecific antibody (TCB) targeting CD22 could be used in the therapy of hematologic malignancies. So, to address the question, we utilized the information of six previously reported CD22 mAbs to generate CD22-TCBs with different avidity to different domains on CD22 protein. We found that the avidity of CD22-TCBs to protein was not consistent with the avidity to target cells, indicating that TCBs had different binding mode to the protein and cells. In vitro results indicated that CD22-TCBs mediated cytotoxicity depended on the avidity of antibodies to target cells rather than to protein. Moreover, distal binding domain of the antigen contributed to the avidity and biological activity of IgG-[L]-scfv-like CD22-TCBs. The T cells' proliferation, activation, cytotoxicity as well as cytokine release were compared, and G5/44 BsAb was selected for further in vivo assessment in anti-tumor activity. In vivo results demonstrated that CD22-TCB (G5/44 BsAb) significantly inhibited the tumors growth in mice. All these data suggested that CD22-TCBs could be developed as a promising candidate for B-cell malignancies therapy through optimizing the design with avidity and binding domain to CD22 target in consideration.

Combination of High-Resolution Structures for the B Cell Receptor and Co-Receptors Provides an Understanding of Their Interactions with Therapeutic Antibodies

B cells are central to the adaptive immune response, providing long lasting immunity after infection. B cell activation is mediated by a cell surface B cell receptor (BCR) following recognition of an antigen. BCR signaling is modulated by several co-receptors including CD22 and a complex that contains CD19 and CD81. Aberrant signaling through the BCR and co-receptors promotes the pathogenesis of several B cell malignancies and autoimmune diseases. Treatment of these diseases has been revolutionized by the development of monoclonal antibodies that bind to B cell surface antigens, including the BCR and its co-receptors. However, malignant B cells can escape targeting by several mechanisms and until recently, rational design of antibodies has been limited by the lack of high-resolution structures of the BCR and its co-receptors. Herein we review recently determined cryo-electron microscopy (cryo-EM) and crystal structures of the BCR, CD22, CD19 and CD81 molecules. These structures provide further understanding of the mechanisms of current antibody therapies and provide scaffolds for development of engineered antibodies for treatment of B cell malignancies and autoimmune diseases.

Target Antigen Attributes and Their Contributions to Clinically Approved Antibody-Drug Conjugates (ADCs) in Haematopoietic and Solid Cancers

Antibody drug conjugates (ADCs) are powerful anti-cancer therapies comprising an antibody joined to a cytotoxic payload through a chemical linker. ADCs exploit the specificity of antibodies for their target antigens, combined with the potency of cytotoxic drugs, to selectively kill target antigen-expressing tumour cells. The recent rapid advancement of the ADC field has so far yielded twelve and eight ADCs approved by the US and EU regulatory bodies, respectively. These serve as effective targeted treatments for several haematological and solid tumour types. In the development of an ADC, the judicious choice of an antibody target antigen with high expression on malignant cells but restricted expression on normal tissues and immune cells is considered crucial to achieve selectivity and potency while minimising on-target off-tumour toxicities. Aside from this paradigm, the selection of an antigen for an ADC requires consideration of several factors relating to the expression pattern and biological features of the target antigen. In this review, we discuss the attributes of antigens selected as targets for antibodies used in clinically approved ADCs for the treatment of haematological and solid malignancies. We discuss target expression, functions, and cellular kinetics, and we consider how these factors might contribute to ADC efficacy.

Emerging phagocytosis checkpoints in cancer immunotherapy

Cancer immunotherapy, mainly including immune checkpoints-targeted therapy and the adoptive transfer of engineered immune cells, has revolutionized the oncology landscape as it utilizes patients' own immune systems in combating the cancer cells. Cancer cells escape immune surveillance by hijacking the corresponding inhibitory pathways via overexpressing checkpoint genes. Phagocytosis checkpoints, such as CD47, CD24, MHC-I, PD-L1, STC-1 and GD2, have emerged as essential checkpoints for cancer immunotherapy by functioning as "don't eat me" signals or interacting with "eat me" signals to suppress immune responses. Phagocytosis checkpoints link innate immunity and adaptive immunity in cancer immunotherapy. Genetic ablation of these phagocytosis checkpoints, as well as blockade of their signaling pathways, robustly augments phagocytosis and reduces tumor size. Among all phagocytosis checkpoints, CD47 is the most thoroughly studied and has emerged as a rising star among targets for cancer treatment. CD47-targeting antibodies and inhibitors have been investigated in various preclinical and clinical trials. However, anemia and thrombocytopenia appear to be formidable challenges since CD47 is ubiquitously expressed on erythrocytes. Here, we review the reported phagocytosis checkpoints by discussing their mechanisms and functions in cancer immunotherapy, highlight clinical progress in targeting these checkpoints and discuss challenges and potential solutions to smooth the way for combination immunotherapeutic strategies that involve both innate and adaptive immune responses.

Sugar-decorated carbon dots: a novel tool for targeting immunomodulatory receptors

Interactions between sialic acid (Sia) and sialic acid-binding immunoglobulin-like lectins (siglecs) regulate the immune system, with aberrations contributing to pathologies such as autoimmunity, infectious disease and cancer. Over the last decade, several multivalent Sia ligands have been synthesized to modulate the Sia-binding affinity of proteins/lectins. Here, we report a novel class of multivalent siglec probes through the decoration of α(2,6)-sialyllactose ligands on inherently fluorescent carbon dots (CD). We show that the preference of α(2,3)-linked Sia for siglec-1 can be altered by increasing the multivalence of Sia ligands present on the CD, and that a locally high glycan concentration can have a direct effect on linkage specificity. Additionally, micromolar (IC₅₀ ∼ 70 μM) interaction of α(2,6)-sialyllactose-CD (6-CD) with siglec-2 (CD22) revealed it was capable of generating a significant cytotoxic effect on Burkitt's Lymphoma (BL) Daudi B cells. This phenonomen was attributed to 6-CD's ability to form trans interactions with CD22 on masked BL Daudi cells as a direct result of clustering of the Sia moiety on the CD surface. Overall, our glycoengineered carbon dots represent a novel high affinity molecular probe with multiple applications in sialoglycoscience and medicine.

A cis-regulatory lexicon of DNA motif combinations mediating cell-type-specific gene regulation

Gene expression is controlled by transcription factors (TFs) that bind cognate DNA motif sequences in cis-regulatory elements (CREs). The combinations of DNA motifs acting within homeostasis and disease, however, are unclear. Gene expression, chromatin accessibility, TF footprinting, and H3K27ac-dependent DNA looping data were generated and a random-forest-based model was applied to identify 7,531 cell-type-specific cis-regulatory modules (CRMs) across 15 diploid human cell types. A co-enrichment framework within CRMs nominated 838 cell-type-specific, recurrent heterotypic DNA motif combinations (DMCs), which were functionally validated using massively parallel reporter assays. Cancer cells engaged DMCs linked to neoplasia-enabling processes operative in normal cells while also activating new DMCs only seen in the neoplastic state. This integrative approach identifies cell-type-specific cis-regulatory combinatorial DNA motifs in diverse normal and diseased human cells and represents a general framework for deciphering cis-regulatory sequence logic in gene regulation.

Autoantibodies in Neuropsychiatric Systemic Lupus Erythematosus (NPSLE): Can They Be Used as Biomarkers for the Differential Diagnosis of This Disease?

Systemic lupus erythematosus is a complex immunological disease where both environmental factors and genetic predisposition lead to the dysregulation of important immune mechanisms. Eventually, the combination of these factors leads to the production of self-reactive antibodies that can target any organ or tissue of the human body. Autoantibodies can form immune complexes responsible for both the organ damage and the most severe complications. Involvement of the central nervous system defines a subcategory of the disease, generally known with the denomination of neuropsychiatric systemic lupus erythematosus. Neuropsychiatric symptoms can range from relatively mild manifestations, such as headache, to more severe complications, such as psychosis. The evaluation of the presence of the autoantibodies in the serum of these patients is the most helpful diagnostic tool for the assessment of the disease. The scientific progresses achieved in the last decades helped researchers and physicians to discover some of autoepitopes targeted by the autoantibodies, although the majority of them have not been identified yet. Additionally, the central nervous system is full of epitopes that cannot be found elsewhere in the human body, for this reason, autoantibodies that selectively target these epitopes might be used for the differential diagnosis between patients with and without the neuropsychiatric symptoms. In this review, the most relevant data is reported with regard to mechanisms implicated in the production of autoantibodies and the most important autoantibodies found among patients with systemic lupus erythematosus with and without the neuropsychiatric manifestations.

Role of B cells as antigen presenting cells

B cells have been long studied for their role and function in the humoral immune system. Apart from generating antibodies and an antibody-mediated memory response against pathogens, B cells are also capable of generating cell-mediated immunity. It has been demonstrated by several groups that B cells can activate antigen-specific CD4 and CD8 T cells, and can have regulatory and cytotoxic effects. The function of B cells as professional antigen presenting cells (APCs) to activate T cells has been largely understudied. This, however, requires attention as several recent reports have demonstrated the importance of B cells within the tumor microenvironment, and B cells are increasingly being evaluated as cellular therapies. Antigen presentation through B cells can be through antigen-specific (B cell receptor (BCR) dependent) or antigen non-specific (BCR independent) mechanisms and can be modulated by a variety of intrinsic and external factors. This review will discuss the pathways and mechanisms by which B cells present antigens, and how B cells differ from other professional APCs.

Abnormal B cell glycosylation in autoimmunity: A new potential treatment strategy

Systemic lupus erythematosus (SLE) and primary Sjögren’s syndrome (pSS) are two autoimmune diseases characterised by the production of pathogenic autoreactive antibodies. Their aetiology is poorly understood. Nevertheless, they have been shown to involve several factors, such as infections and epigenetic mechanisms. They also likely involve a physiological process known as glycosylation. Both SLE T cell markers and pSS-associated autoantibodies exhibit abnormal glycosylation. Such dysregulation suggests that defective glycosylation may also occur in B cells, thereby modifying their behaviour and reactivity. This study aimed to investigate B cell subset glycosylation in SLE, pSS and healthy donors and to extend the glycan profile to serum proteins and immunoglobulins. We used optimised lectin-based tests to demonstrate specific glycosylation profiles on B cell subsets that were specifically altered in both diseases. Compared to the healthy donor B cells, the SLE B cells exhibited hypofucosylation, whereas only the pSS B cells exhibited hyposialylation. Additionally, the SLE B lymphocytes had more galactose linked to N-acetylglucosamine or N-acetylgalactosamine (Gal-GlcNAc/Gal-GalNAc) residues on their cell surface markers. Interestingly, some similar alterations were observed in serum proteins, including immunoglobulins. These findings indicate that any perturbation of the natural glycosylation process in B cells could result in the development of pathogenic autoantibodies. The B cell glycoprofile can be established as a preferred biomarker for characterising pathologies and adapted therapeutics can be used for patients if there is a correlation between the extent of these alterations and the severity of the autoimmune diseases.

Potential of antibody-drug conjugates (ADCs) for cancer therapy

The primary purpose of ADCs is to increase the efficacy of anticancer medications by minimizing systemic drug distribution and targeting specific cells. Antibody conjugates (ADCs) have changed the way cancer is treated. However, because only a tiny fraction of patients experienced long-term advantages, current cancer preclinical and clinical research has been focused on combination trials. The complex interaction of ADCs with the tumor and its microenvironment appear to be reliant on the efficacy of a certain ADC, all of which have significant therapeutic consequences. Several clinical trials in various tumor types are now underway to examine the potential ADC therapy, based on encouraging preclinical results. This review tackles the potential use of ADCs in cancer therapy, emphasizing the essential processes underlying their positive therapeutic impacts on solid and hematological malignancies. Additionally, opportunities are explored to understand the mechanisms of ADCs action, the mechanism of resistance against ADCs, and how to overcome potential resistance following ADCs administration. Recent clinical findings have aroused interest, leading to a large increase in the number of ADCs in clinical trials. The rationale behind ADCs, as well as their primary features and recent research breakthroughs, will be discussed. We then offer an approach for maximizing the potential value that ADCs can bring to cancer patients by highlighting key ideas and distinct strategies.

Engineering the Sialome

The surface of every eukaryotic cell is coated in a dense layer of structurally diverse glycans that together comprise the glycocalyx, a key interface between intracellular biochemistry and the external environment. Many of the glycans within the glycocalyx terminate in anionic monosaccharides belonging to the sialic acid family. Advances in our understanding of the biological processes mediated by sialic acids at the interfaces between cells have catalyzed interest in metabolic, enzymatic, and chemical strategies to edit the total complement of cellular sialic acids-the sialome. Here, we review strategies for altering the composition of the sialome with particular focus on glycan structures and state-of-the-art tools.

Assessment on the lung injury of mice posed by airborne PM2.5 collected from developing area in China and associated molecular mechanisms by integrated analysis of mRNA-seq and miRNA-seq

Some epidemiological evidences showed exposure of airborne fine particulate matter (PM2.5) was associated with lung dysfunction. However, the adverse effects of PM2.5 from mid-scale city of China on the respiratory system were unknown. Correspondingly, the mechanisms, especially the epigenetic mechanism regulated by miRNAs, involved in PM2.5-induced lung injury has not been fully understood. In this study, male Balb/C mice were exposed to PM2.5 collected from mid-scale city (Baoji), China for 8 weeks (mean concentration 298.52 ± 25.86 μg/m3 at exposure chamber) using a whole-body exposure system. The carbon component was the main ingredient (45.80%) of PM2.5 followed by ions (43.19%). Meanwhile, the sum concentrations of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes (C18-C33) were 570.48 and 2029.13 ng/m3 in the exposure chamber, respectively. Obvious lung injury including pulmonary inflammation and fibrosis (p < 0.05 compared with the control) were found from PM2.5 exposure group determined by micro-CT and histopathological assays, respectively, suggesting the health risk posed by PM2.5 from mid-scale city of China should be concerned. The integrated analysis between mRNA-seq and miRNA-seq revealed the differentially expression genes in lung tissues were enriched in immune pathways including B cell receptor signaling (p = 0.078) and cell adhesion molecules (CAMs) (p = 0.0068). The expression profiles of the genes and corresponding mRNAs involved into the immune pathways determined by RT-qPCR analysis were consistent with them conducted by transcriptome. Moreover, the expression levels of the proteins (i.e., CD19, CD81, PIK3CD, and CD22) involved into B cell receptor signaling pathway from exposure group were 1.71- to 6.948- folds compared with the control, validating the results of the genes expression profiles. Further, canonical correlation analysis (CCA) and multiple correlation analysis between the target genes and components of PM2.5 documented the organic compounds (i.e., Benzo(a)pyrene (p = 0.012) and octadecane (p = 0.05)) and inorganic elements (i.e., Cl-, Ti, Al, and Zn) was the key environmental factors. Cd19, Pik3cd, and Cd8b1 might be the key genes for lung dysfunction induced by PM2.5 illuminated using interactive analysis (p < 0.05). This work for the first time showed the adverse effects of PM2.5 in mid-scale city in China on respiratory system should be concerned, and the associated epigenetic mechanism regulated by miRNA were revealed. These results may provide new insight into the development of future assessment on the air pollution associated respiratory disease.

Determining subpopulation methylation profiles from bisulfite sequencing data of heterogeneous samples using DXM

Epigenetic changes, such as aberrant DNA methylation, contribute to cancer clonal expansion and disease progression. However, identifying subpopulation-level changes in a heterogeneous sample remains challenging. Thus, we have developed a computational approach, DXM, to deconvolve the methylation profiles of major allelic subpopulations from the bisulfite sequencing data of a heterogeneous sample. DXM does not require prior knowledge of the number of subpopulations or types of cells to expect. We benchmark DXM's performance and demonstrate improvement over existing methods. We further experimentally validate DXM predicted allelic subpopulation-methylation profiles in four Diffuse Large B-Cell Lymphomas (DLBCLs). Lastly, as proof-of-concept, we apply DXM to a cohort of 31 DLBCLs and relate allelic subpopulation methylation profiles to relapse. We thus demonstrate that DXM can robustly find allelic subpopulation methylation profiles that may contribute to disease progression using bisulfite sequencing data of any heterogeneous sample.

Unlocking the potential of antibody-drug conjugates for cancer therapy

Nine different antibody-drug conjugates (ADCs) are currently approved as cancer treatments, with dozens more in preclinical and clinical development. The primary goal of ADCs is to improve the therapeutic index of antineoplastic agents by restricting their systemic delivery to cells that express the target antigen of interest. Advances in synthetic biochemistry have ushered in a new generation of ADCs, which promise to improve upon the tissue specificity and cytotoxicity of their predecessors. Many of these drugs have impressive activity against treatment-refractory cancers, although hurdles impeding their broader use remain, including systemic toxicity, inadequate biomarkers for patient selection, acquired resistance and unknown benefit in combination with other cancer therapies. Emerging evidence indicates that the efficacy of a given ADC depends on the intricacies of how the antibody, linker and payload components interact with the tumour and its microenvironment, all of which have important clinical implications. In this Review, we discuss the current state of knowledge regarding the design, mechanism of action and clinical efficacy of ADCs as well as the apparent limitations of this treatment class. We then propose a path forward by highlighting several hypotheses and novel strategies to maximize the potential benefit that ADCs can provide to patients with cancer.

Efficacy and Safety of Inotuzumab Ozogamicin (CMC-544) for the Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia and Non-Hodgkin Lymphoma: A Systematic Review and Meta-Analysis

INTRODUCTION

The purpose of this systematic review and meta-analysis was to evaluate the efficacy and safety of inotuzumab ozogamicin (INO) in patients with relapsed/refractory acute lymphocytic leukemia (ALL) and non-Hodgkin lymphoma (NHL).

MATERIALS AND METHODS

Databases (PubMed, EMBASE, and Cochrane databases) were searched through April 4, 2020. Outcome measures of efficacy covered complete remission (CR) rates and minimal residual disease response rates. Safety was evaluated by hepatic venous obstructive disease/sinus obstructive syndrome and grade ≥ 3 hematologic adverse events. We also evaluated the quality of enrolled studies by the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

A total of 12 studies involving 644 patients were included. The summary estimates of the CR and minimal residual disease response rates for patients with ALL were 67% (95% confidence interval [CI], 61%-73%) and 45% (95% CI, 37%-53%) of patients with NHL. The pooled CR rate was 28% (95% CI, 15%-47%). Thrombocytopenia and neutropenia were the most common adverse events. In patients receiving INO, venous obstructive disease/sinus obstructive syndrome, grade ≥ 3 thrombocytopenic events, grade ≥ 3 neutropenic events of the pooled estimated incidence were 8% (95% CI, 5%-14%), 29% (95% CI, 20%-39%), and 48% (95% CI, 38%-57%).

CONCLUSIONS

According to our study, INO was effective in the treatment of relapsed/refractory ALL and NHL with limited adverse effects. High-quality randomized controlled trials and extensive follow-up are pending to confirm and update the results of this analysis in the future.

Liver and spleen transcriptome reveals that Oreochromis aureus under long-term salinity stress may cause excessive energy consumption and immune response

To investigate the physiological responses of Oreochromis aureus to salinity fluctuations at the molecular level. We used RNA-seq to explore the differentially expressed genes (DEGs) in the liver and spleen of O. aureus at 0, 3, 7 and 11 ppt (parts per thousand) salinity levels. Herein, De novo assembly generated 71,009 O. aureus unigenes, of which 34,607 were successfully mapped to the four major databases. A total of 120 shared DEGs were identified in liver and spleen transcripts, of which 83 were up-regulated and 37 were down-regulated. GO and KEGG analysis found a total of 26 significant pathways, mainly including energy metabolism, immune response, ion transporters and signal transduction. The trend module category of DEGs showed that the genes (e.g., FASN, ODC1, CD22, MRC, TRAV and SLC7 family) involved in the change-stable-change (1) and the constant-change categories (2) were highly sensitive to salinity fluctuations, which were of great value for further study. Based on these results, it would help provide basic data for fish salinity acclimation, and provide new insights into evolutionary response of fish to various aquatic environments in the long-term stress adaptation mechanism.

Microanatomy of the Human Atherosclerotic Plaque by Single-Cell Transcriptomics

RATIONALE

Atherosclerotic lesions are known for their cellular heterogeneity, yet the molecular complexity within the cells of human plaques has not been fully assessed.

OBJECTIVE

Using single-cell transcriptomics and chromatin accessibility, we gained a better understanding of the pathophysiology underlying human atherosclerosis.

METHODS AND RESULTS

We performed single-cell RNA and single-cell ATAC sequencing on human carotid atherosclerotic plaques to define the cells at play and determine their transcriptomic and epigenomic characteristics. We identified 14 distinct cell populations including endothelial cells, smooth muscle cells, mast cells, B cells, myeloid cells, and T cells and identified multiple cellular activation states and suggested cellular interconversions. Within the endothelial cell population, we defined subsets with angiogenic capacity plus clear signs of endothelial to mesenchymal transition. CD4+ and CD8+ T cells showed activation-based subclasses, each with a gradual decline from a cytotoxic to a more quiescent phenotype. Myeloid cells included 2 populations of proinflammatory macrophages showing IL (interleukin) 1B or TNF (tumor necrosis factor) expression as well as a foam cell-like population expressing TREM2 (triggering receptor expressed on myeloid cells 2) and displaying a fibrosis-promoting phenotype. ATACseq data identified specific transcription factors associated with the myeloid subpopulation and T cell cytokine profiles underlying mutual activation between both cell types. Finally, cardiovascular disease susceptibility genes identified using public genome-wide association studies data were particularly enriched in lesional macrophages, endothelial, and smooth muscle cells.

CONCLUSIONS

This study provides a transcriptome-based cellular landscape of human atherosclerotic plaques and highlights cellular plasticity and intercellular communication at the site of disease. This detailed definition of cell communities at play in atherosclerosis will facilitate cell-based mapping of novel interventional targets with direct functional relevance for the treatment of human disease.

Clinical Significance of Inotuzumab Ozogamicin in Non-transplant Patients with Relapsed Acute Lymphoblastic Leukemia: A Report of Four Cases

Relapsed acute lymphoblastic leukemia (ALL) has a poor prognosis. Inotuzumab Ozogamicin (InO) is a novel therapeutic drug for the treatment of relapsed ALL. InO has received attention as a bridging therapy before transplantation due to its high complete remission (CR) rate. However, the significance of InO in non-transplant patients remains unclear. We retrospectively evaluated four non-transplant patients treated with InO. All cases achieved CR after receiving at least two cycles of InO. Three of the four cases survived for more than 11 months without relapse. Moreover, all patients received InO as outpatients, because the adverse events were well-controlled. InO therefore appears to be a beneficial treatment even for non-transplant patients.

Quantitative trait loci and genes associated with salmonid alphavirus load in Atlantic salmon: implications for pancreas disease resistance and tolerance

Salmonid alphavirus infection results in pancreas disease causing severe economic losses for Atlantic salmon aquaculture. Knowledge about genes and pathways contributing to resistance is limited. A 54 K SNP panel was used to genotype 10 full-sibling families each consisting of ~ 110 offspring challenged with salmonid alphavirus subtype 3. Relative heart viral load was assessed at 4- and 10-weeks post-infection using quantitative PCR. A moderate genomic heritability of viral load at 4 weeks (0.15–0.21) and a high positive correlation with survival (0.91–0.98) were detected. Positions of QTL detected on chromosome 3 matched those for survival detected by other studies. The SNP of highest significance occurred in the 3′ untranslated region of gig1, a fish-specific antiviral effector. Locus B of immunoglobulin heavy chain mapped to an area containing multiple SNPs with genome-wide association. Heart mRNA-seq comparing parr from families with high- versus low-genomic breeding value, and matching sample genotypes for SNPs, identified two eQTL for salmonid alphavirus load. Immune genes associated with trans-eQTL were numerous and spread throughout the genome. QTL regions contained several genes with known or predicted immune functions, some differentially expressed. The putative functional genes and variants identified could help improve marker-based selection for pancreas disease resistance.

Siglecs as Immune Cell Checkpoints in Disease

Sialic acid-binding immunoglobulin-type lectins (Siglecs) are expressed on the majority of white blood cells of the immune system and play critical roles in immune cell signaling. Through recognition of sialic acid-containing glycans as ligands, they help the immune system distinguish between self and nonself. Because of their restricted cell type expression and roles as checkpoints in immune cell responses in human diseases such as cancer, asthma, allergy, neurodegeneration, and autoimmune diseases they have gained attention as targets for therapeutic interventions. In this review we describe the Siglec family, its roles in regulation of immune cell signaling, current efforts to define its roles in disease processes, and approaches to target Siglecs for treatment of human disease.

Response of the Salmon Heart Transcriptome to Pancreas Disease: Differences Between High- and Low-Ranking Families for Resistance

Pancreas disease caused by salmonid alphaviruses leads to severe losses in Atlantic salmon aquaculture. The aim of our study was to gain a better understanding of the biological differences between salmon with high and low genomic breeding values (H-gEBV and L-gEBV respectively) for pancreas disease resistance. Fish from H- and L-gEBV families were challenged by intraperitoneal injection of salmonid alphavirus or co-habitation with infected fish. Mortality was higher with co-habitation than injection, and for L- than H-gEBV. Heart for RNA-seq and histopathology was collected before challenge and at four- and ten-weeks post-challenge. Heart damage was less severe in injection-challenged H- than L-gEBV fish at week 4. Viral load was lower in H- than L-gEBV salmon after co-habitant challenge. Gene expression differences between H- and L-gEBV manifested before challenge, peaked at week 4, and moderated by week 10. At week 4, H-gEBV salmon showed lower expression of innate antiviral defence genes, stimulation of B- and T-cell immune function, and weaker stress responses. Retarded resolution of the disease explains the higher expression of immune genes in L-gEBV at week 10. Results suggest earlier mobilization of acquired immunity better protects H-gEBV salmon by accelerating clearance of the virus and resolution of the disease.

Immunotherapy in pediatric acute lymphoblastic leukemia

The 5-year survival rate for children and adolescents with acute lymphoblastic leukemia (ALL) has improved to more than 90% in high-income countries. However, further increases in the intensity of conventional chemotherapy would be associated with significant adverse effects; therefore, novel approaches are necessary. The last decade has seen significant advances in targeted therapy with immunotherapy and molecular therapeutics, as well as advances in risk stratification for therapy based on somatic and germline genetic analysis and monitoring of minimal residual disease. For immunotherapy, the approval of antibody-based therapy (with blinatumomab in 2014 and inotuzumab ozogamicin in 2017) and T cell-based therapy (with tisagenlecleucel in 2017) by the US Food and Drug Administration has significantly improved the response rate and outcomes in patients with relapsed/refractory B-ALL. These strategies have also been tested in the frontline setting, and immunotherapy against a new ALL-associated antigen has been developed. Incorporating effective immunotherapy into ALL therapy would enable the intensity of conventional chemotherapy to be decreased and thereby reduce associated toxicity, leading to further improvement in survival and quality of life for patients with ALL.

Moxetumomab pasudotox-tdfk for relapsed/refractory hairy cell leukemia: a review of clinical considerations

PURPOSE

Hairy cell leukemia (HCL) is a rare mature B cell leukemia. Purine analogs are the mainstay of treatment of HCL, but relapse after purine analog therapy is common. Outcomes of treatment of relapsed/refractory HCL typically diminish with each successive line of therapy. Moxetumomab pasudotox-tdfk is a novel recombinant immunotoxin approved for the treatment of patients with relapsed/refractory HCL who have received at least two prior therapies, including a purine analog. This article reviews HCL treatment, focusing on moxetumomab pasudotox-tdfk, its place in therapy, considerations for preparation and administration, and strategies for prevention and management of toxicities.

METHODS

A literature search was conducted in the PubMed database from inception to January 2019, using the following terms: moxetumomab, hairy cell leukemia, relapsed/refractory hairy cell leukemia, immunotoxin, and CD22. The package insert and available posters and abstracts were also reviewed.

RESULTS

FDA approval of moxetumomab pasudotox-tdfk was based on a phase III single-arm, open-label trial in 80 patients. Treatment with moxetumomab pasudotox-tdfk yielded a durable complete response rate of 30% with a median duration of response that had not yet been reached at a median follow-up of 16.7 months. The objective response rate was 75% based on blinded independent central review. The most common adverse reactions were infusion-related reactions, edema, nausea, fatigue, headache, pyrexia and anemia. Serious adverse events include capillary leak syndrome and hemolytic uremic syndrome.

CONCLUSIONS

Clinicians providing care for patients receiving moxetumomab pasudotox-tdfk should be aware of the strategies required for safe administration, including the management of serious adverse events.

Inotuzumab ozogamicin: a CD22 mAb-drug conjugate for adult relapsed or refractory B-cell precursor acute lymphoblastic leukemia

Despite improved rates of remission and cure in newly diagnosed adult acute lymphoblastic leukemia (ALL), the prognosis for patients with relapsed or refractory disease remains poor and the 5-year overall survival rate after relapse is under 10%. A recent paradigm shift has focused on the promise of targeted immunotherapy rather than standard chemotherapy, as ALL blast cells express a variety of antigens, and monoclonal antibodies may be developed to identify and destroy the leukemic cells. Inotuzumab ozogamicin is a CD22 monoclonal antibody conjugated to the cytotoxic antibiotic calicheamicin. CD22 expression is detected on leukemic blasts in over 90% of patients with ALL. Based on promising results from preclinical studies, inotuzumab ozogamicin was tested in Phase 1/2 and Phase 3 clinical trials and it demonstrated improved complete remission rates, progression-free survival and overall survival in relapsed or refractory adult ALL compared to standard therapy. Ongoing studies are evaluating the value of inotuzumab ozogamicin when given in combination with chemotherapy as part of upfront treatment. This review discusses the drug’s biochemical properties and mechanism of action, preclinical research outcomes, clinical trial results, adverse events and toxicities, drug approval and ongoing investigations.

Antibody-Drug Conjugates for Cancer Therapy: Chemistry to Clinical Implications

Chemotherapy is one of the major therapeutic options for cancer treatment. Chemotherapy is often associated with a low therapeutic window due to its poor specificity towards tumor cells/tissues. Antibody-drug conjugate (ADC) technology may provide a potentially new therapeutic solution for cancer treatment. ADC technology uses an antibody-mediated delivery of cytotoxic drugs to the tumors in a targeted manner, while sparing normal cells. Such a targeted approach can improve the tumor-to-normal tissue selectivity and specificity in chemotherapy. Considering its importance in cancer treatment, we aim to review recent efforts for the design and development of ADCs. ADCs are mainly composed of an antibody, a cytotoxic payload, and a linker, which can offer selectivity against tumors, anti-cancer activity, and stability in systemic circulation. Therefore, we have reviewed recent updates and principal considerations behind ADC designs, which are not only based on the identification of target antigen, cytotoxic drug, and linker, but also on the drug-linker chemistry and conjugation site at the antibody. Our review focuses on site-specific conjugation methods for producing homogenous ADCs with constant drug-antibody ratio (DAR) in order to tackle several drawbacks that exists in conventional conjugation methods.

Development and characterization of a camelid single-domain antibody directed to human CD22 biomarker

CD22 is a B-cell-specific trans-membrane glycoprotein, which is found on the surface of the most B cells and modulates their function, survival, and apoptosis. Recently, targeting this cell surface biomarker in B-cell malignancies and disorders has attracted a lot of attention. The variable domain of camelid single-chain antibodies (VHH, nanobody) is a form of antibodies with novel properties including small size (15-17 kDa), thermal and chemical stability, high affinity and homology to human antibody sequences. In this study, a novel anti-CD22-specific VHH (Nb) has been developed and characterized by the screening of an immunized phage display library and its binding to CD22⁺ B cells is evaluated. Produced anti-CD22 VHH had a single protein band about 17 kDa of molecular size in Western blotting and its binding affinity was approximately 9 × 10^-9  M. Also, this product had high specificity and it was able to recognize the natural CD22 antigen in CD22+ cell lysate as well as on the cell surface (93%). This anti-CD22 VHH with both high affinity and specificity recognizes CD22 antigen well and can be used in diagnosis and treatment of B cell disorders and malignancies.

Immune System Dysfunction in the Elderly

Human aging is characterized by both physical and physiological frailty that profoundly affects the immune system. In this context aging is associated with declines in adaptive and innate immunity established as immunosenescence. Immunosenescence is a new concept that reflects the age-associated restructuring changes of innate and adaptive immune functions. Thus elderly individuals usually present chronic low-level inflammation, higher infection rates and chronic diseases. A study of alterations in the immune system during aging could provide a potentially useful biomarker for the evaluation of immune senescence treatment. The immune system is the result of the interplay between innate and adaptive immunity, yet the impact of aging on this function is unclear. In this article the function of the immune system during aging is explored.

Novel Immunotherapy Agents for Acute Lymphoblastic Leukaemia

Acute lymphoblastic leukaemia (ALL) in adults has a survival rate of 40–50% at 5 years, with a high relapse rate after first-line chemotherapy. After relapse, results with salvage therapy are currently unsatisfactory. Therefore, both the optimisation of front-line therapy to reduce relapse incidence and the search for effective salvage therapies for relapsed/refractory (r/r) ALL have been of great interest to the medical community in recent years. The well-characterised expression of well-defined cell-surface antigens in B cell ALL (B)-ALL and T cell (T)-ALL, such as CD19, CD20, CD22, and CD52, has led to the development of several immunotherapy strategies, comprising ‘nude’ monoclonal antibodies (moAbs), conjugated moAbs, bispeciphic, or highly sophisticated chimeric antigen receptor (CAR)-T cell therapy. Recently, both the bispecific moAb blinatumomab (anti-CD19 coupled with a CD3 recognition subunit) and the conjugated anti-CD22 moAb inotuzumab-ozogamicin have resulted in higher remission rates (44% versus 25%, and 80.7% versus 29.4%, respectively) and survival advantages (median overall survival [OS]: 7.7 months versus 4 months, and 7.7 months versus 6.7 months, respectively) in patients with r/r B-ALL when compared to standard salvage chemotherapy-based regimens. On the other hand, preliminary reports show feasibility and unprecedented response rates of ≤90% in highly refractory children and adults treated with CAR-modified T cells targeting the B cell specific CD19 antigen, which seem to be durable in a significant proportion of patients. Furthermore, the addition of anti-CD20 moAb rituximab to front-line standard chemotherapy in patients with CD20+ B-ALL has resulted in a clinical benefit, with prolongation of response duration and survival (3-year leukaemia-free survival and OS: 70% versus 38%; p<0.001, and 75% versus 47%; p=0.003). In conclusion, immunotherapy is currently providing additional options for high-risk ALL patients both in front-line or advanced phase. Nonetheless, the optimal positioning of these novel agents, specially in relation to allogeneic haematopoietic stem-cell transplantion, needs to be clarified. This article aims to review several of these new therapeutic immunotherapy options available for patients with adult ALL, as well as their specific toxicity profile.

Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia in Adults

Patients with relapsed and refractory acute lymphoblastic leukemia (ALL) have a dismal prognosis with less than 10 % of patients surviving 5 years. Most such patients cannot be rescued with currently available therapies, whatever the initial treatment they receive. Therefore, there is an urgent need for novel treatment options. Fortunately, over the past several years, an improved understanding of the biology of the disease has allowed the identification of rational molecular targets for therapeutic endeavors and the emergence of novel therapies has sparked great interest. This review will discuss the current treatment landscape for adult patients with relapsed and/or refractory ALL.

An interaction map of circulating metabolites, immune gene networks, and their genetic regulation

BACKGROUND

Immunometabolism plays a central role in many cardiometabolic diseases. However, a robust map of immune-related gene networks in circulating human cells, their interactions with metabolites, and their genetic control is still lacking. Here, we integrate blood transcriptomic, metabolomic, and genomic profiles from two population-based cohorts (total N = 2168), including a subset of individuals with matched multi-omic data at 7-year follow-up.

RESULTS

We identify topologically replicable gene networks enriched for diverse immune functions including cytotoxicity, viral response, B cell, platelet, neutrophil, and mast cell/basophil activity. These immune gene modules show complex patterns of association with 158 circulating metabolites, including lipoprotein subclasses, lipids, fatty acids, amino acids, small molecules, and CRP. Genome-wide scans for module expression quantitative trait loci (mQTLs) reveal five modules with mQTLs that have both cis and trans effects. The strongest mQTL is in ARHGEF3 (rs1354034) and affects a module enriched for platelet function, independent of platelet counts. Modules of mast cell/basophil and neutrophil function show temporally stable metabolite associations over 7-year follow-up, providing evidence that these modules and their constituent gene products may play central roles in metabolic inflammation. Furthermore, the strongest mQTL in ARHGEF3 also displays clear temporal stability, supporting widespread trans effects at this locus.

CONCLUSIONS

This study provides a detailed map of natural variation at the blood immunometabolic interface and its genetic basis, and may facilitate subsequent studies to explain inter-individual variation in cardiometabolic disease.

RNA-Seq and CyTOF immuno-profiling of regenerating lacrimal glands identifies a novel subset of cells expressing muscle-related proteins

The purpose of the present studies was to use CyTOF and RNA-Seq technologies to identify cells and genes involved in lacrimal gland repair that could be targeted to treat diseases of lacrimal gland dysfunction. Lacrimal glands of female BALB/c mice were experimentally injured by intra-glandular injection of interleukin 1 alpha (IL-1α). The lacrimal glands were harvested at various time points following injury (1 to 14 days) and used to either prepare single cell suspensions for CyTOF immuno-phenotyping analyses or to extract RNA for gene expression studies using RNA-Seq. CyTOF immuno-phenotyping identified monocytes and neutrophils as the major infiltrating populations 1 and 2 days post injury. Clustering of significantly differentially expressed genes identified 13 distinct molecular signatures: 3 associated with immune/inflammatory processes included genes up-regulated at days 1–2 and 3 associated with reparative processes with genes up-regulated primarily between days 4 and 5. Finally, clustering identified 65 genes which were specifically up-regulated 2 days post injury which was enriched for muscle specific genes. The expression of select muscle-related proteins was confirmed by immunohistochemistry which identified a subset of cells expressing these proteins. Double staining experiments showed that these cells are distinct from the myoepithelial cells. We conclude that experimentally induced injury to the lacrimal gland leads to massive infiltration by neutrophils and monocytes which resolved after 3 days. RNAseq and immunohistochemistry identified a group of cells, other than myoepithelial cells, that express muscle-related proteins that could play an important role in lacrimal gland repair.

The HB22.7-vcMMAE antibody-drug conjugate has efficacy against non-Hodgkin lymphoma mouse xenografts with minimal systemic toxicity

In this study, HB22.7, an anti-CD22 monoclonal antibody, was used for specific, targeted delivery of monomethyl auristatin E (MMAE) to non-Hodgkin lymphoma (NHL). MMAE was covalently coupled to HB22.7 through a valine-citrulline peptide linker (vc). Maleimide-functionalized vcMMAE (mal-vcMMAE) was reacted with thiols of the partially reduced mAb. Approximately 4 molecules of MMAE were conjugated to HB22.7 as determined by residual thiol measurement and hydrophobic interaction chromatography-HPLC (HIC-HPLC). HB22.7-vcMMAE antibody-drug conjugate (ADC) retained its binding to Ramos NHL cells and also exhibited potent and specific in vitro cytotoxicity on a panel of B cell NHL cell lines with IC50s of 20-284 ng/ml. HB22.7-vcMMAE also showed potent efficacy in vivo against established NHL xenografts using the DoHH2 and Granta 519 cell lines. One dose of the ADC induced complete and persistent response in all DoHH2 xenografts and 90 % of Granta xenografts. Minimal toxicity was observed. In summary, HB22.7-vcMMAE is an effective ADC that should be evaluated for clinical translation.

Ectopic expression of a novel CD22 splice-variant regulates survival and proliferation in malignant T cells from cutaneous T cell lymphoma (CTCL) patients

CD22 is a member of the Sialic acid-binding Ig-like lectin (Siglec) family of lectins described to be exclusively present in B lymphocytes and B cell-derived neoplasms. Here, we describe a novel splice form of CD22 (designated CD22∆N), which lacks the N-terminal domain as demonstrated by exon-specific RT-PCR and differential recognition by anti-CD22 antibodies. Importantly, CD22∆N mRNA is expressed in skin lesions from 39 out of 60 patients with cutaneous T cell lymphoma (CTCL), whereas few patients (6 out of 60) expresses full-length, wild type CD22 (CD22wt). In addition, IHC staining of tumor biopsies confirmed the expression of CD22 in CD4+ T cells. Moreover, four out of four malignant T cell lines express CD22: Two cell lines express CD22∆N (MyLa2059 and PB2B) and two express CD22wt (MAC-1 and MAC-2A). siRNA-mediated silencing of CD22 impairs proliferation and survival of malignant T cells, demonstrating a functional role for both CD22∆N and CD22wt in these cells.In conclusion, we provide the first evidence for an ectopic expression of CD22 and a novel splice variant regulating malignant proliferation and survival in CTCL. Analysis of expression and function of CD22 in cutaneous lymphomas may form the basis for development of novel targeted therapies for our patients.

Analyses of 123 Peripheral Human Immune Cell Subsets: Defining Differences with Age and between Healthy Donors and Cancer Patients Not Detected in Analysis of Standard Immune Cell Types

Recent advances in human immunology have led to the identification of novel immune cell subsets and the biological function of many of these subsets has now been identified. The recent US Food and Drug Administration approval of several immunotherapeutics for the treatment of a variety of cancer types and the results of ongoing immunotherapy clinical studies requires a more thorough interrogation of the immune system. We report here the use of flow cytometry-based analyses to identify 123 immune cell subsets of peripheral blood mononuclear cells. The use of these panels defines multiple differences in younger (< 40 years) vs. older (≥ 40 years) individuals and between aged-matched apparently healthy individuals and metastatic cancer patients, aspects not seen in the analysis of the following standard immune cell types: CD8, CD4, natural killer, natural killer-T, regulatory T, myeloid derived suppressor cells, conventional dendritic cells (DCs), plasmacytoid DCs and B cells. The use of these panels identifying 123 immune cell subsets may aid in the identification of patients who may benefit from immunotherapy, either prior to therapy or early in the immunotherapeutic regimen, for the treatment of cancer or other chronic or infectious diseases.

Role of inotuzumab ozogamicin in the treatment of relapsed/refractory acute lymphoblastic leukemia

Inotuzumab ozogamicin is a humanized anti-CD22 monoclonal antibody bound to a toxic natural calicheamicin, which is under investigation for the treatment of relapsed/refractory acute lymphoblastic leukemia. CD22 is commonly expressed in 90-100% of malignant mature B-lymphocyte lineage. The first Phase II study with inotuzumab ozogamicin conducted by Kantarjian et al. gave the opportunity for heavily pretreated patients with acute lymphoblastic leukemia to go for allogeneic stem cell transplant. Inotuzumab is well-tolerated with the exception of veno-occlusive disease. Overall inotuzumab ozogamicin is potentially an encouraging and promising therapy for patients.

Extensive crosslinking of CD22 by epratuzumab triggers BCR signaling and caspase-dependent apoptosis in human lymphoma cells

Epratuzumab has demonstrated therapeutic activity in patients with non-Hodgkin lymphoma, acute lymphoblastic leukemia, systemic lupus erythematosus, and Sjögren's syndrome, but its mechanism of affecting normal and malignant B cells remains incompletely understood. We reported previously that epratuzumab displayed in vitro cytotoxicity to CD22-expressing Burkitt lymphoma cell lines (Daudi and Ramos) only when immobilized on plates or combined with a crosslinking antibody plus a suboptimal amount of anti-IgM (1 μg/mL). Herein, we show that, in the absence of additional anti-IgM ligation, extensive crosslinking of CD22 by plate-immobilized epratuzumab induced intracellular changes in Daudi cells similar to ligating B-cell antigen receptor with a sufficiently high amount of anti-IgM (10 μg/mL). Specifically, either treatment led to phosphorylation of CD22, CD79a and CD79b, along with their translocation to lipid rafts, both of which were essential for effecting caspase-dependent apoptosis. Moreover, such immobilization induced stabilization of F-actin, phosphorylation of Lyn, ERKs and JNKs, generation of reactive oxygen species (ROS), decrease in mitochondria membrane potential (Δψ_m), upregulation of pro-apoptotic Bax, and downregulation of anti-apoptotic Bcl-xl and Mcl-1. The physiological relevance of immobilized epratuzumab was implicated by noting that several of its in vitro effects, including apoptosis, drop in Δψ_m, and generation of ROS, could be observed with soluble epratuzumab in Daudi cells co-cultivated with human umbilical vein endothelial cells. These results suggest that the in vivo mechanism of non-ligand-blocking epratuzumab may, in part, involve the unmasking of CD22 to facilitate the trans-interaction of B cells with vascular endothelium.

Anti-CD83 promotes IgG1 isotype switch in marginal zone B cells in response to TI-2 antigen

CD83 is a transmembrane glycoprotein that is rapidly up-regulated on activated B cells. Although CD83 itself is incapable to transduce intracellular signaling, it acts as a negative regulator of B cell function. We have recently described that a single application of anti-CD83 antibody results in dramatically enhanced production of antigen-specific IgG1 but not other isotypes upon immunization of mice with the TI-2 model antigen (Ag) NIP-Ficoll. This effect was mediated by the binding of anti-CD83 to CD83 on the surface of B cells themselves. In the current study we show that administration of anti-CD83 enhances IgG1-production independent of IL-4. Application of anti-CD83 does not alter the proliferation and general expansion of NIP-specific B cells. In the presence of anti-CD83, immunized mice develop normal frequencies of plasmablasts in response to NIP-Ficoll of which an increased number produces IgG1. These cells localize in extrafollicular foci in the spleen of immunized mice and originate from the marginal zone B cell pool. Taken together, our results indicate that CD83 engagement in vivo does not generally enhance B cell activation but selectively promotes IgG1 class switch in marginal zone B cells in response to TI-2 Ag.