Bispecific Antibodies: From Research to Clinical Application

PHE1-based IgG-like antibody platform provides a novel strategy for enhanced T-cell immunotherapy

Introduction

Bispecific antibodies (BsAbs) can simultaneously target two epitopes of different antigenic targets, bringing possibilities for diversity in antibody drug design and are promising tools for the treatment of cancers and other diseases. T-cell engaging bsAb is an important application of the bispecific antibody, which could promote T cell-mediated tumor cell killing by targeting tumor-associated antigen (TAA) and CD3 at the same time.

Methods

This study comprised antibodies purification, Elisa assay for antigen binding, cytotoxicity assays, T cell activation by flow cytometry in vitro and xenogenic tumor model in vivo.

Results

We present a novel bsAb platform named PHE-Ig technique to promote cognate heavy chain (HC)-light chain (LC) pairing by replacing the CH1/CL regions of different monoclonal antibodies (mAbs) with the natural A and B chains of PHE1 fragment of Integrin β2 based on the knob-in-hole (KIH) technology. We had also verified that PHE-Ig technology can be effectively used as a platform to synthesize different desired bsAbs for T-cell immunotherapy. Especially, BCMA×CD3 PHE-Ig bsAbs exhibited robust anti-multiple myeloma (MM) activity in vitro and in vivo.

Discussion

Moreover, PHE1 domain was further shortened with D14G and R41S mutations, named PHE-S, and the PHE-S-based BCMA×CD3 bsAbs also showed anti BCMA+ tumor effect in vitro and in vivo, bringing more possibilities for the development and optimization of different bsAbs. To sum up, PHE1-based IgG-like antibody platform for bsAb construction provides a novel strategy for enhanced T-cell immunotherapy.

Current Novel Targeted Therapeutic Strategies in Multiple Myeloma

Multiple myeloma (MM) is a hematologic malignancy caused by the clonal expansion of immunoglobulin-producing plasma cells in the bone marrow and/or extramedullary sites. Common manifestations of MM include anemia, renal dysfunction, infection, bone pain, hypercalcemia, and fatigue. Despite numerous recent advancements in the MM treatment paradigm, current therapies demonstrate limited long-term effectiveness and eventual disease relapse remains exceedingly common. Myeloma cells often develop drug resistance through clonal evolution and alterations of cellular signaling pathways. Therefore, continued research of new targets in MM is crucial to circumvent cumulative drug resistance, overcome treatment-limiting toxicities, and improve outcomes in this incurable disease. This article provides a comprehensive overview of the landscape of novel treatments and emerging therapies for MM grouped by molecular target. Molecular targets outlined include BCMA, GPRC5D, FcRH5, CD38, SLAMF7, BCL-2, kinesin spindle protein, protein disulfide isomerase 1, peptidylprolyl isomerase A, Sec61 translocon, and cyclin-dependent kinase 6. Immunomodulatory drugs, NK cell therapy, and proteolysis-targeting chimera are described as well.

Bispecific Antibody Use in Patients With Lymphoma and Multiple Myeloma

This article endeavors to navigate the clinical journey of bispecific antibodies (BsAbs), from elucidating common toxicities and management strategies to examining novel agents and broadening access in community health care. These drugs, commonly through T-cell activation, result in shared adverse events such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome. Variations in target antigens and designs, however, might introduce unique toxicities for different BsAbs, warranting specific management approaches. Recent US Food and Drug Administration approvals of BsAbs targeting CD3+ T cells linked to CD20 for non-Hodgkin lymphoma and to B-cell maturation antigen or GPRC5D for multiple myeloma have transformed the treatment landscape for hematologic malignancies. Emerging new agents promise further enhancement and safety, exploring novel antigen targets, innovative structures such as trispecific antibodies, and the engagement of diverse immune cells. Simultaneously, the expansion of BsAbs into community practices is underway, demanding a multifaceted strategy that encompasses educational initiatives, operational adaptations, and collaborative frameworks. This ensures comprehensive treatment access, allowing every patient, irrespective of geographical or socioeconomic status, to benefit from these advancements in cancer therapy.

Colorectal cancer: a comprehensive review of carcinogenesis, diagnosis, and novel strategies for classified treatments

Colorectal cancer is the third most common and the second deadliest cancer worldwide. To date, colorectal cancer becomes one of the most important challenges of the health system in many countries. Since the clinical symptoms of this cancer appear in the final stages of the disease and there is a significant golden time between the formation of polyps and the onset of cancer, early diagnosis can play a significant role in reducing mortality. Today, in addition to colonoscopy, minimally invasive methods such as liquid biopsy have received much attention. The treatment of this complex disease has been mostly based on traditional treatments including surgery, radiotherapy, and chemotherapy; the high mortality rate indicates a lack of success for current treatment methods. Moreover, disease recurrence is another problem of traditional treatments. Recently, new approaches such as targeted therapy, immunotherapy, and nanomedicine have opened new doors for cancer treatment, some of which have already entered the market, and many methods have shown promising results in clinical trials. The success of immunotherapy in the treatment of refractory disease, the introduction of these methods into neoadjuvant therapy, and the successful results in tumor shrinkage without surgery have made immunotherapy a tough competitor for conventional treatments. It seems that the combination of those methods with such targeted therapies will go through promising changes in the future of colorectal cancer treatment.

Characterization of a novel format scFv×VHH single-chain biparatopic antibody against metal binding protein MtsA

Biparatopic antibodies (bpAbs) are engineered antibodies that bind to multiple different epitopes within the same antigens. bpAbs comprise diverse formats, including fragment-based formats, and choosing the appropriate molecular format for a desired function against a target molecule is a challenging task. Moreover, optimizing the design of constructs requires selecting appropriate antibody modalities and adjusting linker length for individual bpAbs. Therefore, it is crucial to understand the characteristics of bpAbs at the molecular level. In this study, we first obtained single-chain variable fragments and camelid heavy-chain variable domains targeting distinct epitopes of the metal binding protein MtsA and then developed a novel format single-chain bpAb connecting these fragment antibodies with various linkers. The physicochemical properties, binding activities, complex formation states with antigen, and functions of the bpAb were analyzed using multiple approaches. Notably, we found that the assembly state of the complexes was controlled by a linker and that longer linkers tended to form more compact complexes. These observations provide detailed molecular information that should be considered in the design of bpAbs.

Bispecific Nanobody-Aptamer Conjugates for Enhanced Cancer Therapy in Solid Tumors

Bispecific antibodies possess exceptional potential as therapeutic agents due to their capacity to bind to two different antigens simultaneously. However, challenges pertain to unsatisfactory stability, manufacturing complexity, and limited tumor penetration hinder their broad applicability. In this study, a versatile technology is presented for the rapid generation of bispecific nanobody-aptamer conjugates with efficient tumor penetration. The approach utilizes microbial transglutaminase (MTGase) and click chemistry to achieve site-specific conjugation of nanobodies and aptamers, which are termed nanotamers. The nanotamers recognize and bind to two types of molecular targets expressed on cancer cells. As a prototype, a bispecific nanotamer is developed that binds both clusters of differentiation 47 (CD47) and mesenchymal epithelial transition receptor (Met) expressed on the tumor cell membrane. This CD47-Met nanotamer demonstrates high affinity and specificity toward tumor cells expressing both targets, exhibits improved receptor functional inhibition through a strong steric hindrance effect. Moreover, its capacity for deep tumor penetration greatly enhances the impact of conventional chemotherapy on antitumor efficacy. The as-developed nanotamer synthesis approach shows promise to customize bispecific molecular probes targeting different cancer types and different therapeutic goals.

Structural and functional characterization of IgG- and non-IgG-based T-cell-engaging bispecific antibodies

Bispecific T-cell-engaging antibodies are a growing class of therapeutics with numerous molecules being tested in clinical trials and, currently, seven of them have received market approval. They are structurally complex and function as adaptors to redirect the cytotoxicity of T cells to kill tumor cells. T-cell-engaging bispecific antibodies can be generally divided into two categories: IgG/IgG-like and non-IgG-like formats. Different formats may have different intrinsic potencies and physiochemical properties, and comprehensive studies are needed to gain a better understanding of how the differences in formats impact on structural and functional characteristics. In this study, we designed and generated bispecific T-cell-engaging antibodies with IgG-like (DVD-Ig) and non-IgG (BiTE) formats. Both target the same pair of antigens (EGFR and CD3) to minimize the possible influence of targets on functional characterization. We performed a side-by-side comparison to assess differences in the physiochemical and biological properties of these two bispecific T-cell-engaging antibodies using a variety of breast and ovarian cancer cell-based functional assays to delineate the structural-functional relationships and anti-tumor activities/potency. We found that the Fc portion of T-cell-engaging bispecific antibodies can significantly impact antigen binding activity, potency, and stability in addition to eliciting different mechanisms of action that contribute the killing of cancer cells.

The Evolution of Antibody-Drug Conjugates: Toward Accurate DAR and Multi-specificity

Antibody-drug conjugates (ADCs) consist of antibodies, linkers and payloads. They offer targeted delivery of potent cytotoxic drugs to tumor cells, minimizing off-target effects. However, the therapeutic efficacy of ADCs is compromised by heterogeneity in the drug-to-antibody ratio (DAR), which impacts both cytotoxicity and pharmacokinetics (PK). Additionally, the emergence of drug resistance poses significant challenges to the clinical advancement of ADCs. To overcome these limitations, a variety of strategies have been developed, including the design of multi-specific drugs with accurate DAR. This review critically summarizes the current challenges faced by ADCs, categorizing key issues and evaluating various innovative solutions. We provide an in-depth analysis of the latest methodologies for achieving homogeneous DAR and explore design strategies for multi-specific drugs aimed at combating drug resistance. Our discussion offers a current perspective on the advancements made in refining ADC technologies, with an emphasis on enhancing therapeutic outcomes.

Geometric Antibody Engineering Reveals the Spatial Factor on the Efficacy of Bispecific T Cell Engagers

Bispecific antibodies (BsAbs) represent an emerging class of biologics that can recognize two different antigens or epitopes. T-cell engagers (TcEs) bind two targets in trans on the cell surface of the effector and target cell to induce proximal immune effects, opening exciting windows for immunotherapies. To date, the engineering of BsAbs has been mainly focused on tuning the molecular weight and valency. However, the effects of spatial factors on the biological functions of BsAbs have been less explored due to the lack of biochemical methods to precisely manipulate protein geometry. Here, we studied the geometric effects of the TcEs. First, by genetically inserting rigidly designed ankyrin repeat proteins into TcEs, we revealed that the efficacy progressively decreased as the spacer distance of the two binding domains increased. Then, we constructed 26 pairs of TcEs with the same size but varying orientations using click chemistry-mediated conjugation at different mutation sites. We found that linear ligation sites play a minor role in modulating cell-killing efficacy. Next, we rendered the TcEs' advanced topology by cyclization chemistry using the SpyTag/SpyCatcher pair or sortase ligation approaches. Cyclized TcEs were generally more potent than their linear counterparts. Particularly, sortase A cyclized TcEs, bearing a minimal tagging motif, exhibited better cell-killing efficacy in vitro and improved stability both in vitro and in vivo compared to the linear TcE. This work combines modern bioconjugation chemistry and protein engineering tools for antibody engineering, shedding light on the elusive spatial factors of BsAbs functionality.

Efficacy and safety of bispecific antibodies vs. immune checkpoint blockade combination therapy in cancer: a real-world comparison

Emerging tumor immunotherapy methods encompass bispecific antibodies (BSABs), immune checkpoint inhibitors (ICIs), and adoptive cell immunotherapy. BSABs belong to the antibody family that can specifically recognize two different antigens or epitopes on the same antigen. These antibodies demonstrate superior clinical efficacy than monoclonal antibodies, indicating their role as a promising tumor immunotherapy option. Immune checkpoints are also important in tumor immunotherapy. Programmed cell death protein-1 (PD-1) is a widely acknowledged immune checkpoint target with effective anti-tumor activity. PD-1 inhibitors have demonstrated notable therapeutic efficacy in treating hematological and solid tumors; however, more than 50% of patients undergoing this treatment exhibit a poor response. However, ICI-based combination therapies (ICI combination therapies) have been demonstrated to synergistically increase anti-tumor effects and immune response rates. In this review, we compare the clinical efficacy and side effects of BSABs and ICI combination therapies in real-world tumor immunotherapy, aiming to provide evidence-based approaches for clinical research and personalized tumor diagnosis and treatment.

A Novel Dual-Fc Bispecific Antibody with Enhanced Fc Effector Function

Bispecific antibodies (BsAbs) are undergoing continued development for applications in oncology and autoimmune diseases. While increasing activity by having more than one targeting arm, most BsAb engineering employs single Fc engagement as monoclonal antibodies. Here, we designed a novel immunoglobulin gamma-1 (IgG1)-derived dual-Fc BsAb containing two Fc regions and two distinct asymmetric antigen binding arms comprising a Fab arm and another VHH domain. In conjunction with the knob-into-hole technology, dual-Fc BsAbs could be produced with a high yield and good stability. We explore how Fc engineering effects on dual-Fc constructs could boost the desired therapeutic efficacy. This new format enabled simultaneous bispecific binding to corresponding antigens. Furthermore, compared to the one-Fc control molecules, dual-Fc BsAbs were shown to increase the avidity-based binding to FcγRs to result in higher ADCC and ADCP activities by potent avidity via binding to two antigens and Fc receptors. Overall, this novel BsAb format with enhanced effector functionalities provides a new option for antibody-based immunotherapy.

Combinatorially restricted computational design of protein-protein interfaces to produce IgG heterodimers

Redesigning protein-protein interfaces is an important tool for developing therapeutic strategies. Interfaces can be redesigned by in silico screening, which allows for efficient sampling of a large protein space before experimental validation. However, computational costs limit the number of combinations that can be reasonably sampled. Here, we present combinatorial tyrosine (Y)/serine (S) selection (combYSelect), a computational approach combining in silico determination of the change in binding free energy (ΔΔG) of an interface with a highly restricted library composed of just two amino acids, tyrosine and serine. We used combYSelect to design two immunoglobulin G (IgG) heterodimers-combYSelect1 (L368S/D399Y-K409S/T411Y) and combYSelect2 (D399Y/K447S-K409S/T411Y)-that exhibit near-optimal heterodimerization, without affecting IgG stability or function. We solved the crystal structures of these heterodimers and found that dynamic π-stacking interactions and polar contacts drive preferential heterodimeric interactions. Finally, we demonstrated the utility of our combYSelect heterodimers by engineering both a bispecific antibody and a cytokine trap for two unique therapeutic applications.

Advancements in cancer immunotherapies targeting CD20: from pioneering monoclonal antibodies to chimeric antigen receptor-modified T cells

CD20 located predominantly on the B cells plays a crucial role in their development, differentiation, and activation, and serves as a key therapeutic target for the treatment of B-cell malignancies. The breakthrough of monoclonal antibodies directed against CD20, notably exemplified by rituximab, revolutionized the prognosis of B-cell malignancies. Rituximab, approved across various hematological malignancies, marked a paradigm shift in cancer treatment. In the current landscape, immunotherapies targeting CD20 continue to evolve rapidly. Beyond traditional mAbs, advancements include antibody-drug conjugates (ADCs), bispecific antibodies (BsAbs), and chimeric antigen receptor-modified (CAR) T cells. ADCs combine the precision of antibodies with the cytotoxic potential of drugs, presenting a promising avenue for enhanced therapeutic efficacy. BsAbs, particularly CD20xCD3 constructs, redirect cytotoxic T cells to eliminate cancer cells, thereby enhancing both precision and potency in their therapeutic action. CAR-T cells stand as a promising strategy for combatting hematological malignancies, representing one of the truly personalized therapeutic interventions. Many new therapies are currently being evaluated in clinical trials. This review serves as a comprehensive summary of CD20-targeted therapies, highlighting the progress and challenges that persist. Despite significant advancements, adverse events associated with these therapies and the development of resistance remain critical issues. Understanding and mitigating these challenges is paramount for the continued success of CD20-targeted immunotherapies.

Development of Plant-Derived Bispecific Monoclonal Antibody Targeting PD-L1 and CTLA-4 against Mouse Colorectal Cancer

Checkpoint blockade immunotherapy has revolutionized cancer treatment, with monoclonal antibodies targeting immune checkpoints, yielding promising clinical benefits. However, with the advent of resistance to immune checkpoint inhibitor treatment in clinical trials, developing next-generation antibodies with potentially increased efficacy is critical. Here, we aimed to generate a recombinant bispecific monoclonal antibody for dual inhibition of programmed cell death protein 1/programmed cell death ligand 1 and cytotoxic T-lymphocyte-associated protein 4 axes. The plant system was used as an alternative platform for bispecific monoclonal antibody production. Dual variable domain immunoglobulin atezolizumab × 2C8 is a plant-derived bispecific monoclonal antibody that combines both programmed cell death ligand 1 and cytotoxic T-lymphocyte-associated protein 4 blockade into a single molecule. Dual variable domain immunoglobulin atezolizumab × 2C8 was transiently expressed in Nicotiana benthamiana and the expression level was determined to be the highest after 4 days of infiltration. The size and assembly of the purified bispecific monoclonal antibody were determined, and its function was investigated in vitro and in vivo. The molecular structures of plant-produced dual variable domain immunoglobulin atezolizumab × 2C8 are as expected, and it was mostly present as a monomer. The plant-produced dual variable domain immunoglobulin atezolizumab × 2C8 showed in vitro binding to programmed cell death ligand 1 and cytotoxic T-lymphocyte-associated protein 4 proteins. The antitumor activity of plant-produced bispecific monoclonal antibody was tested in vivo by treating humanized Balb/c mice bearing a CT26 colorectal tumor. Plant-produced dual variable domain immunoglobulin atezolizumab × 2C8 significantly inhibited tumor growth by reducing tumor volume and weight. Body weight changes indicated that the plant-produced bispecific monoclonal antibody was safe and tolerable. Overall, this proof of concept study demonstrated the viability of plants to produce functional plant-based bispecific immunotherapy.

Engineered polyspecific antibodies: A new frontier in the field of immunotherapeutics

The 21st-century beginning remarked with the huge success of monospecific MAbs, however, in the last couple of years, polyspecific MAbs (PsAbs) have been an interesting topic and show promise of being biobetter than monospecific MAbs. Polyspecificity, in which a single antibody serves multiple specific target binding, has been hypothesized to contribute to the development of a highly effective antibody repertoire for immune defence. This polyspecific MAb trend represents an explosion that is gripping the whole pharmaceutical industry. This review is concerned with the current development and quality enforcement of PsAbs. All provided literature on monospecific MAbs and polyspecific MAbs (PsAbs) were searched using various electronic databases such as PubMed, Google Scholar, Web of Science, Elsevier, Springer, ACS, Google Patent and books via the keywords Antibody engineering, Polyspecific antibody, Conventional antibody, non-conventional antibody, and Single domain antibody. In the literature, there are more than 100 different formats to construct PsAb by quadroma technology, chemical conjugation and genetic engineering. Till March 2023, nine PsAb have been approved around the world, and around 330 are in advanced developmental stages, showing the dominancy of PsAb in the growing health sector. Recent advancements in protein engineering techniques and the fusion of non-conventional antibodies have made it possible to create complex PsAbs that demonstrate higher stability and enhanced potency. This marks the most significant achievement for cancer immunotherapy, in which PsAbs have immense promise. It is worth mentioning that seven out of the nine PsAbs have been approved as anti-cancer therapy. As PsAbs continue to acquire prominence, they could pave the way for the development of novel immunotherapies for multiple diseases.

Advancements in γδT cell engineering: paving the way for enhanced cancer immunotherapy

Comprising only 1-10% of the circulating T cell population, γδT cells play a pivotal role in cancer immunotherapy due to their unique amalgamation of innate and adaptive immune features. These cells can secrete cytokines, including interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α), and can directly eliminate tumor cells through mechanisms like Fas/FasL and antibody-dependent cell-mediated cytotoxicity (ADCC). Unlike conventional αβT cells, γδT cells can target a wide variety of cancer cells independently of major histocompatibility complex (MHC) presentation and function as antigen-presenting cells (APCs). Their ability of recognizing antigens in a non-MHC restricted manner makes them an ideal candidate for allogeneic immunotherapy. Additionally, γδT cells exhibit specific tissue tropism, and rapid responsiveness upon reaching cellular targets, indicating a high level of cellular precision and adaptability. Despite these capabilities, the therapeutic potential of γδT cells has been hindered by some limitations, including their restricted abundance, unsatisfactory expansion, limited persistence, and complex biology and plasticity. To address these issues, gene-engineering strategies like the use of chimeric antigen receptor (CAR) T therapy, T cell receptor (TCR) gene transfer, and the combination with γδT cell engagers are being explored. This review will outline the progress in various engineering strategies, discuss their implications and challenges that lie ahead, and the future directions for engineered γδT cells in both monotherapy and combination immunotherapy.

COVID-19 cooling: Nanostrategies targeting cytokine storm for controlling severe and critical symptoms

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continue to wreak havoc worldwide, the "Cytokine Storm" (CS, also known as the inflammatory storm) or Cytokine Release Syndrome has reemerged in the public consciousness. CS is a significant contributor to the deterioration of infected individuals. Therefore, CS control is of great significance for the treatment of critically ill patients and the reduction of mortality rates. With the occurrence of variants, concerns regarding the efficacy of vaccines and antiviral drugs with a broad spectrum have grown. We should make an effort to modernize treatment strategies to address the challenges posed by mutations. Thus, in addition to the requirement for additional clinical data to monitor the long-term effects of vaccines and broad-spectrum antiviral drugs, we can use CS as an entry point and therapeutic target to alleviate the severity of the disease in patients. To effectively combat the mutation, new technologies for neutralizing or controlling CS must be developed. In recent years, nanotechnology has been widely applied in the biomedical field, opening up a plethora of opportunities for CS. Here, we put forward the view of cytokine storm as a therapeutic target can be used to treat critically ill patients by expounding the relationship between coronavirus disease 2019 (COVID-19) and CS and the mechanisms associated with CS. We pay special attention to the representative strategies of nanomaterials in current neutral and CS research, as well as their potential chemical design and principles. We hope that the nanostrategies described in this review provide attractive treatment options for severe and critical COVID-19 caused by CS.

Research progress on novel antibody drug conjugates in cancer therapy

Traditional antibody drug conjugates (ADC) combine monoclonal antibodies with cytotoxic drugs to accurately strike cancer cells, but there are still many shortcomings in stability, targeting, efficacy, and safety. Novel ADC, such as bi-specific, site-specific, dual-payload, and pro-drug type ADC, can be optimized by simultaneously binding 2 different antigens or epitopes, selecting more stable linkers, coupling with specific amino acid sites of antibodies, carrying different drug payloads, and adopting prodrug strategies, while retaining the characteristics of traditional ADC. Significantly improving the stability, targeting, efficacy and safety of drugs can better meet the needs of clinical treatment. Novel ADC will play a more important role in cancer treatment in the future. Discussing the progress of novel ADC in cancer treatment and analyzing their advantages and challenges can provide theoretical support for the development of anti-cancer strategies and provide directions for drug research and development.

An Engineered Mouse Model That Generates a Diverse Repertoire of Endogenous, High-Affinity Common Light Chain Antibodies

Bispecific antibodies have gained increasing popularity as therapeutics as they enable novel activities that cannot be achieved with monospecific antibodies. Some of the most popular bispecific formats are molecules in which two Fab arms with different antigen specificities are combined into one IgG-like molecule. One way to produce these bispecific molecules requires the discovery of antibodies against the two antigens of interest that share a common light chain. Here, we present the generation and characterization of a common light chain mouse model, in which the endogenous IGKJ cluster is replaced with a prearranged, modified murine IGKV10-96/IGKJ1 segment. We demonstrate that genetic modification does not impact B-cell development. Upon immunization with ovalbumin, the animals generate an antibody repertoire with VH gene segment usage of a similar diversity to wildtype mice, while the light chain diversity is restricted to antibodies derived from the prearranged IGKV10-96/IGKJ1 germline. We further show that the clonotype diversity of the common light chain immune repertoire matches the diversity of immune repertoire isolated from wildtype mice. Finally, the common light chain anti-ovalbumin antibodies have only slightly lower affinities than antibodies isolated from wildtype mice, demonstrating the suitability of these animals for antibody discovery for bispecific antibody generation.

A Generic Approach for Miniaturized Unbiased High-Throughput Screens of Bispecific Antibodies and Biparatopic Antibody-Drug Conjugates

The toolbox of modern antibody engineering allows the design of versatile novel functionalities exceeding nature's repertoire. Many bispecific antibodies comprise heterodimeric Fc portions recently validated through the approval of several bispecific biotherapeutics. While heterodimerization methodologies have been established for low-throughput large-scale production, few approaches exist to overcome the bottleneck of large combinatorial screening efforts that are essential for the identification of the best possible bispecific antibody. This report presents a novel, robust and miniaturized heterodimerization process based on controlled Fab-arm exchange (cFAE), which is applicable to a variety of heterodimeric formats and compatible with automated high-throughput screens. Proof of applicability was shown for two therapeutic molecule classes and two relevant functional screening read-outs. First, the miniaturized production of biparatopic anti-c-MET antibody-drug conjugates served as a proof of concept for their applicability in cytotoxic screenings on tumor cells with different target expression levels. Second, the automated workflow enabled a large unbiased combinatorial screening of biparatopic antibodies and the identification of hits mediating potent c-MET degradation. The presented workflow utilizes standard equipment and may serve as a facile, efficient and robust method for the discovery of innovative therapeutic agents in many laboratories worldwide.

Claudin 18.2 as a New Biomarker in Gastric Cancer-What Should We Know?

Gastric cancer (GC) remains a formidable global health challenge, ranking among the top-five causes of cancer-related deaths worldwide. The majority of patients face advanced stages at diagnosis, with a mere 6% five-year survival rate. First-line treatment for metastatic GC typically involves a fluoropyrimidine and platinum agent combination; yet, predictive molecular markers have proven elusive. This review navigates the evolving landscape of GC biomarkers, with a specific focus on Claudin 18.2 (CLDN18.2) as an emerging and promising target. Recent phase III trials have unveiled the efficacy of Zolbetuximab, a CLDN18.2-targeting antibody, in combination with oxaliplatin-based chemotherapy for CLDN18.2-positive metastatic GC. As this novel therapeutic avenue unfolds, understanding the nuanced decision making regarding the selection of anti-CLDN18.2 therapies over other targeted agents in metastatic GC becomes crucial. This manuscript reviews the evolving role of CLDN18.2 as a biomarker in GC and explores the current status of CLDN18.2-targeting agents in clinical development. The aim is to provide concise insights into the potential of CLDN18.2 as a therapeutic target and guide future clinical decisions in the management of metastatic GC.

Structural and functional analysis of engineered antibodies for cancer immunotherapy: insights into protein compactness and solvent accessibility

Antibodies are crucial tools in various biomedical applications, including immunotherapy. In this study, we focused on designing and engineering antibodies to enhance their structural dynamics and functional properties. By employing advanced computational techniques and experimental validation, we gained crucial insights into the impact of specific mutations on the engineered antibodies. This study investigates the design and engineering of antibodies to improve their structural dynamics and functional properties. Structural attributes, such as protein compactness and solvent accessibility, were assessed, revealing interesting trends in anti-CD3 and anti-HER2 antibodies. Mutations in CD3 antibodies resulted in a more stable conformation, while mutant HER2 antibodies exhibited altered interaction with the target. Analysis of secondary structure assignments demonstrated significant changes in the folding and stability of the mutant antibodies compared to the wild-type counterparts. The conformational landscape of the engineered antibodies was explored, providing insights into folding pathways and binding mechanisms. Overall, the current study highlights the significance of antibody design and engineering in modulating structural dynamics and functional properties. The findings contribute to developing improved immunotherapeutic strategies by optimising antibody-based therapeutics for targeted diseases with enhanced efficacy and precision.Communicated by Ramaswamy H. Sarma.

A Bispecific Modeling Framework Enables the Prediction of Efficacy, Toxicity, and Optimal Molecular Design of Bispecific Antibodies Targeting MerTK

Inhibiting MerTK on macrophages is a promising therapeutic strategy for augmenting anti-tumor immunity. However, blocking MerTK on retinal pigment epithelial cells (RPEs) results in retinal toxicity. Bispecific antibodies (bsAbs) containing an anti-MerTK therapeutic and anti-PD-L1 targeting arm were developed to reduce drug binding to MerTK on RPEs, since PD-L1 is overexpressed on macrophages but not RPEs. In this study, we present a modeling framework using in vitro receptor occupancy (RO) and pharmacokinetics (PK) data to predict efficacy, toxicity, and therapeutic index (TI) of anti-MerTK bsAbs. We first used simulations and in vitro RO data of anti-MerTK monospecific antibody (msAb) to estimate the required MerTK RO for in vivo efficacy and toxicity. Using these estimated RO thresholds, we employed our model to predict the efficacious and toxic doses for anti-MerTK bsAbs with varying affinities for MerTK. Our model predicted the highest TI for the anti-MerTK/PD-L1 bsAb with an attenuated MerTK binding arm, which was consistent with in vivo efficacy and toxicity observations. Subsequently, we used the model, in combination with sensitivity analysis and parameter scans, to suggest an optimal molecular design of anti-MerTK bsAb with the highest predicted TI in humans. Our prediction revealed that this optimized anti-MerTK bsAb should contain a MerTK therapeutic arm with relatively low affinity, along with a high affinity targeting arm that can bind to a low abundance target with slow turnover rate. Overall, these results demonstrated that our modeling framework can guide the rational design of bsAbs.

Impact of antibody architecture and paratope valency on effector functions of bispecific NKp30 x EGFR natural killer cell engagers

Natural killer (NK) cells emerged as a promising effector population that can be harnessed for anti-tumor therapy. In this work, we constructed NK cell engagers (NKCEs) based on NKp30-targeting single domain antibodies (sdAbs) that redirect the cytotoxic potential of NK cells toward epidermal growth factor receptor (EGFR)-expressing tumor cells. We investigated the impact of crucial parameters such as sdAb location, binding valencies, the targeted epitope on NKp30, and the overall antibody architecture on the redirection capacity. Our study exploited two NKp30-specific sdAbs, one of which binds a similar epitope on NKp30 as its natural ligand B7-H6, while the other sdAb addresses a non-competing epitope. For EGFR-positive tumor targeting, humanized antigen-binding domains of therapeutic antibody cetuximab were used. We demonstrate that NKCEs bivalently targeting EGFR and bivalently engaging NKp30 are superior to monovalent NKCEs in promoting NK cell-mediated tumor cell lysis and that the architecture of the NKCE can substantially influence killing capacities depending on the NKp30-targeting sdAb utilized. While having a pronounced impact on NK cell killing efficacy, the capabilities of triggering antibody-dependent cellular phagocytosis or complement-dependent cytotoxicity were not significantly affected comparing the bivalent IgG-like NKCEs with cetuximab. However, the fusion of sdAbs can have a slight impact on the NK cell release of immunomodulatory cytokines, as well as on the pharmacokinetic profile of the NKCE due to unfavorable spatial orientation within the molecule architecture. Ultimately, our findings reveal novel insights for the engineering of potent NKCEs triggering the NKp30 axis.

Exploring molecular determinants and pharmacokinetic properties of IgG1-scFv bispecific antibodies

Bispecific antibodies (BsAbs) capable of recognizing two distinct epitopes or antigens offer promising therapeutic options for various diseases by targeting multiple pathways. The favorable pharmacokinetic (PK) properties of monoclonal antibodies (mAbs) are crucial, as they directly influence patient safety and therapeutic efficacy. For numerous mAb therapeutics, optimization of neonatal Fc receptor (FcRn) interactions and elimination of unfavorable molecular properties have led to improved PK properties. However, many BsAbs exhibit unfavorable PK, which has precluded their development as drugs. In this report, we present studies on the molecular determinants underlying the distinct PK profiles of three IgG1-scFv BsAbs. Our study indicated that high levels of nonspecific interactions, elevated isoelectric point (pI), and increased number of positively charged patches contributed to the fast clearance of IgG1-scFv. FcRn chromatography results revealed specific scFv-FcRn interactions that are unique to the IgG1-scFv, which was further supported by molecular dynamics (MD) simulation. These interactions likely stabilize the BsAb FcRn interaction at physiological pH, which in turn could disrupt FcRn-mediated BsAb recycling. In addition to the empirical observations, we also evaluated the impact of in silico properties, including pI differential between the Fab and scFv and the ratio of dipole moment to hydrophobic moment (RM) and their correlation with the observed clearance. These findings highlight that the PK properties of BsAbs may be governed by novel determinants, owing to their increased structural complexity compared to immunoglobulin G (IgG) 1 antibodies.

Rapid purification of mAb using protein a membranes yielding high HCP clearance

Protein A chromatography remains the crucial step in mAb purification because of the high binding specificity and impurity clearance. In recent years, highly productive membrane adsorbers emerged as an alternative to traditional resins allowing for rapid purification of biomolecules. In this study, we tested three commercially available protein A membranes (Sartobind® Rapid A, HiTrap Fibro™ PrismA and GORE™ Protein Capture Device) regarding flow distribution, permeability and binding performance. As an application study using a cell-culture supernatant (CCS) containing monoclonal antibodies (mAbs), acidic and high pH wash steps were investigated regarding recovery and impurity removal. All membranes proved their applicability as highly productive capture media leading to high HCP and DNA removal with no observable influence on recovery. GORE™ Protein Capture Device exhibited a superior flow distribution but revealed diffusional limitations at high flow rates. Sartobind® Rapid A and HiTrap Fibro™ PrismA showed binding capacities of ∼ 40 g/L even at residence times (RTs) < 12 s but were limited by hydrodynamics suggesting room for improvement with optimized membrane housing.

Discovery of natural bispecific antibodies: Is psoriasis induced by a toxigenic Corynebacterium simulans and maintained by CIDAMPs as autoantigens?

The high abundance of Corynebacterium simulans in psoriasis skin suggests a contribution to the psoriasis aetiology. This hypothesis was tested in an exploratory study, where western blot (WB) analyses with extracts of heat-treated C. simulans and psoriasis serum-derived IgG exhibited a single 16 kDa-WB-band. Proteomic analyses revealed ribosomal proteins as candidate C. s.-antigens. A peptidomic analysis unexpectedly showed that psoriasis serum-derived IgG already contained 31 immunopeptides of Corynebacteria ssp., suggesting the presence of natural bispecific antibodies (BsAbs). Moreover, peptidomic analyses gave 372 DECOY-peptides with similarity to virus- and phage proteins, including Corynebacterium diphtheriae phage, and similarity to diphtheria toxin. Strikingly, a peptidomic analysis for human peptides revealed 64 epitopes of major psoriasis autoantigens such as the spacer region of filaggrin, hornerin repeats and others. Most identified immunopeptides represent potential cationic intrinsically disordered antimicrobial peptides (CIDAMPs), which are generated within the epidermis. These may form complexes with bacterial disordered protein regions, representing chimeric antigens containing discontinuous epitopes. In addition, among 128 low-abundance immunopeptides, 48 are putatively psoriasis-relevant such as epitope peptides of PGE2-, vitamin D3- and IL-10-receptors. Further, 47 immunopeptides originated from tumour antigens, and the endogenous retrovirus HERV-K. I propose that persistent infection with a toxigenic C. simulans initiates psoriasis, which is exacerbated as an autoimmune disease by CIDAMPs as autoantigens. The discovery of natural BsAbs allows the identification of antigen epitopes from microbes, viruses, autoantigens and tumour-antigens, and may help to develop epitope-specific peptide-vaccines and therapeutic approaches with antigen-specific regulatory T cells to improve immune tolerance in an autoimmune disease-specific-manner.

Advancements in CRISPR screens for the development of cancer immunotherapy strategies

CRISPR screen technology enables systematic and scalable interrogation of gene function by using the CRISPR-Cas9 system to perturb gene expression. In the field of cancer immunotherapy, this technology has empowered the discovery of genes, biomarkers, and pathways that regulate tumor development and progression, immune reactivity, and the effectiveness of immunotherapeutic interventions. By conducting large-scale genetic screens, researchers have successfully identified novel targets to impede tumor growth, enhance anti-tumor immune responses, and surmount immunosuppression within the tumor microenvironment (TME). Here, we present an overview of CRISPR screens conducted in tumor cells for the purpose of identifying novel therapeutic targets. We also explore the application of CRISPR screens in immune cells to propel the advancement of cell-based therapies, encompassing T cells, natural killer cells, dendritic cells, and macrophages. Furthermore, we outline the crucial components necessary for the successful implementation of immune-specific CRISPR screens and explore potential directions for future research.

Introduction of Carbonyl Groups into Antibodies

Antibodies and their derivatives (scFv, Fabs, etc.) represent a unique class of biomolecules that combine selectivity with the ability to target drug delivery. Currently, one of the most promising endeavors in this field is the development of molecular diagnostic tools and antibody-based therapeutic agents, including antibody-drug conjugates (ADCs). To meet this challenge, it is imperative to advance methods for modifying antibodies. A particularly promising strategy involves the introduction of carbonyl groups into the antibody that are amenable to further modification by biorthogonal reactions, namely aliphatic, aromatic, and α-oxo aldehydes, as well as aliphatic and aryl-alkyl ketones. In this review, we summarize the preparation methods and applications of site-specific antibody conjugates that are synthesized using this approach.

Revolutionizing cancer immunotherapy: unleashing the potential of bispecific antibodies for targeted treatment

Recent progressions in immunotherapy have transformed cancer treatment, providing a promising strategy that activates the immune system of the patient to find and eliminate cancerous cells. Bispecific antibodies, which engage two separate antigens or one antigen with two distinct epitopes, are of tremendous concern in immunotherapy. The bi-targeting idea enabled by bispecific antibodies (BsAbs) is especially attractive from a medical standpoint since most diseases are complex, involving several receptors, ligands, and signaling pathways. Several research look into the processes in which BsAbs identify different cancer targets such angiogenesis, reproduction, metastasis, and immune regulation. By rerouting cells or altering other pathways, the bispecific proteins perform effector activities in addition to those of natural antibodies. This opens up a wide range of clinical applications and helps patients with resistant tumors respond better to medication. Yet, further study is necessary to identify the best conditions where to use these medications for treating tumor, their appropriate combination partners, and methods to reduce toxicity. In this review, we provide insights into the BsAb format classification based on their composition and symmetry, as well as the delivery mode, focus on the action mechanism of the molecule, and discuss the challenges and future perspectives in BsAb development.

Recent Advances in the Development of Monoclonal Antibodies and Next-Generation Antibodies

mAbs are highly indispensable tools for diagnostic, prophylactic, and therapeutic applications. The first technique, hybridoma technology, was based on fusion of B lymphocytes with myeloma cells, which resulted in generation of single mAbs against a specific Ag. Along with hybridoma technology, several novel and alternative methods have been developed to improve mAb generation, ranging from electrofusion to the discovery of completely novel technologies such as B cell immortalization; phage, yeast, bacterial, ribosome, and mammalian display systems; DNA/RNA encoded Abs; single B cell technology; transgenic animals; and artificial intelligence/machine learning. This commentary outlines the evolution, methodology, advantages, and limitations of various mAb production techniques. Furthermore, with the advent of next-generation Ab technologies such as single-chain variable fragments, nanobodies, bispecific Abs, Fc-engineered Abs, Ab biosimilars, Ab mimetics, and Ab-drug conjugates, the healthcare and pharmaceutical sectors have become resourceful to develop highly specific mAb treatments against various diseases such as cancer and autoimmune and infectious diseases.

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.

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.

The PD-1- and LAG-3-targeting bispecific molecule tebotelimab in solid tumors and hematologic cancers: a phase 1 trial

Tebotelimab, a bispecific PD-1×LAG-3 DART molecule that blocks both PD-1 and LAG-3, was investigated for clinical safety and activity in a phase 1 dose-escalation and cohort-expansion clinical trial in patients with solid tumors or hematologic malignancies and disease progression on previous treatment. Primary endpoints were safety and maximum tolerated dose of tebotelimab when administered as a single agent (n = 269) or in combination with the anti-HER2 antibody margetuximab (n = 84). Secondary endpoints included anti-tumor activity. In patients with advanced cancer treated with tebotelimab monotherapy, 68% (184/269) experienced treatment-related adverse events (TRAEs; 22% were grade ≥3). No maximum tolerated dose was defined; the recommended phase 2 dose (RP2D) was 600 mg once every 2 weeks. There were tumor decreases in 34% (59/172) of response-evaluable patients in the dose-escalation cohorts, with objective responses in multiple solid tumor types, including PD-1-refractory disease, and in LAG-3+ non-Hodgkin lymphomas, including CAR-T refractory disease. To enhance potential anti-tumor responses, we tested margetuximab plus tebotelimab. In patients with HER2+ tumors treated with tebotelimab plus margetuximab, 74% (62/84) had TRAEs (17% were grade ≥3). The RP2D was 600 mg once every 3 weeks. The confirmed objective response rate in these patients was 19% (14/72), including responses in patients typically not responsive to anti-HER2/anti-PD-1 combination therapy. ClinicalTrials.gov identifier: NCT03219268 .

Mechanistically modeling peripheral cytokine dynamics following bispecific dosing in solid tumors

Bispecific antibodies exhibit proven clinical benefit, and many bispecifics are currently in clinical development for oncology. Cytokine release syndrome (CRS) is a common clinical adverse effect observed following CD3-based bispecific dosing. However, the pathophysiology of CRS is not fully understood, and no computational model mechanistically describing clinical cytokine dynamics following bispecific dosing in solid tumors exists. Here, a quantitative systems pharmacology (QSP) model describing peripheral clinical cytokine dynamics following bispecific dosing in solid tumors is presented. Using tebentafusp as a case study, a CD3-bispecific approved for uveal melanoma, the model successfully captures the dynamics of five cytokines. The QSP model was shown to predict observed phenomena, such as cytokine maximum concentration suppression using step-up dosing regimens and the importance of on-target off-tumor binding toward CRS and toxicity. Furthermore, the QSP model provides rationale for these biological phenomena based on dynamics of immune cell activation and desensitization in tumors and healthy tissues. Overall, the QSP model structure presented here serves as a basis to infer cytokine dynamics for other CD3-based bispecifics or tumor types by altering model parameters to capture the scenario of interest, supporting applications including dose selection, candidate nomination, and disease area selection.

Programmable multispecific DNA-origami-based T-cell engagers

Multispecific antibodies have emerged as versatile therapeutic agents, and therefore, approaches to optimize and streamline their design and assembly are needed. Here we report on the modular and programmable assembly of IgG antibodies, F(ab) and scFv fragments on DNA origami nanocarriers. We screened 105 distinct quadruplet antibody variants in vitro for the ability to activate T cells in the presence of target cells. T-cell engagers were identified, which in vitro showed the specific and efficient T-cell-mediated lysis of five distinct target cell lines. We used these T-cell engagers to target and lyse tumour cells in vivo in a xenograft mouse tumour model. Our approach enables the rapid generation, screening and testing of bi- and multispecific antibodies to facilitate preclinical pharmaceutical development from in vitro discovery to in vivo proof of concept.

Effective clearance of rituximab-resistant tumor cells by breaking the mirror-symmetry of immunoglobulin G and simultaneous binding to CD55 and CD20

Complement-dependent cytotoxicity (CDC), which eliminates aberrant target cells through the assembly and complex formation of serum complement molecules, is one of the major effector functions of anticancer therapeutic antibodies. In this study, we discovered that breaking the symmetry of natural immunoglobulin G (IgG) antibodies significantly increased the CDC activity of anti-CD20 antibodies. In addition, the expression of CD55 (a checkpoint inhibitor in the CDC cascade) was significantly increased in a rituximab-resistant cell line generated in-house, suggesting that CD55 overexpression might be a mechanism by which cancer cells acquire rituximab resistance. Based on these findings, we developed an asymmetric bispecific antibody (SBU-CD55 × CD20) that simultaneously targets both CD55 and CD20 to effectively eliminate rituximab-resistant cancer cells. In various cancer cell lines, including rituximab-resistant lymphoma cells, the SBU-CD55 × CD20 antibody showed significantly higher CDC activity than either anti-CD20 IgG antibody alone or a combination of anti-CD20 IgG antibody and anti-CD55 IgG antibody. Furthermore, the asymmetric bispecific antibody (SBU-CD55 × CD20) exhibited significantly higher CDC activity against rituximab-resistant cancer cells compared to other bispecific antibodies with symmetric features. These results demonstrate that enhancing CDC with an asymmetric CD55-binding bispecific antibody could be a new strategy for developing therapeutics to treat patients with relapsed or refractory cancers.

Evaluation of the Neutralizing Antibody STE90-C11 against SARS-CoV-2 Delta Infection and Its Recognition of Other Variants of Concerns

As of now, the COVID-19 pandemic has spread to over 770 million confirmed cases and caused approximately 7 million deaths. While several vaccines and monoclonal antibodies (mAb) have been developed and deployed, natural selection against immune recognition of viral antigens by antibodies has fueled the evolution of new emerging variants and limited the immune protection by vaccines and mAb. To optimize the efficiency of mAb, it is imperative to understand how they neutralize the variants of concern (VoCs) and to investigate the mutations responsible for immune escape. In this study, we show the in vitro neutralizing effects of a previously described monoclonal antibody (STE90-C11) against the SARS-CoV-2 Delta variant (B.1.617.2) and its in vivo effects in therapeutic and prophylactic settings. We also show that the Omicron variant avoids recognition by this mAb. To define which mutations are responsible for the escape in the Omicron variant, we used a library of pseudovirus mutants carrying each of the mutations present in the Omicron VoC individually. We show that either 501Y or 417K point mutations were sufficient for the escape of Omicron recognition by STE90-C11. To test how escape mutations act against a combination of antibodies, we tested the same library against bispecific antibodies, recognizing two discrete regions of the spike antigen. While Omicron escaped the control by the bispecific antibodies, the same antibodies controlled all mutants with individual mutations.

Immunotherapy in Acute Myeloid Leukemia: A Literature Review of Emerging Strategies

In the last twenty years, we have witnessed a paradigm shift in the treatment and prognosis of acute myeloid leukemia (AML), thanks to the introduction of new efficient drugs or approaches to refine old therapies, such as Gemtuzumab Ozogamicin, CPX 3-5-1, hypomethylating agents, and Venetoclax, the optimization of conditioning regimens in allogeneic hematopoietic stem cell transplantation and the improvement of supportive care. However, the long-term survival of non-M3 and non-core binding factor-AML is still dismal. For this reason, the expectations for the recently developed immunotherapies, such as antibody-based therapy, checkpoint inhibitors, and chimeric antigen receptor strategies, successfully tested in other hematologic malignancies, were very high. The inherent characteristics of AML blasts hampered the development of these treatments, and the path of immunotherapy in AML has been bumpy. Herein, we provide a detailed review of potential antigenic targets, available data from pre-clinical and clinical trials, and future directions of immunotherapies in AML.

Editorial on "Cell Therapy, Bispecific Antibodies and Other Immunotherapies against Cancer"

This Special Issue in Cancers, "Cell Therapy, Bispecific Antibodies and other Immunotherapies Against Cancer", includes interesting reports and reviews on cell therapies and bispecific antibodies [...].

NK cell subsets and dysfunction during viral infection: a new avenue for therapeutics?

In the setting of viral challenge, natural killer (NK) cells play an important role as an early immune responder against infection. During this response, significant changes in the NK cell population occur, particularly in terms of their frequency, location, and subtype prevalence. In this review, changes in the NK cell repertoire associated with several pathogenic viral infections are summarized, with a particular focus placed on changes that contribute to NK cell dysregulation in these settings. This dysregulation, in turn, can contribute to host pathology either by causing NK cells to be hyperresponsive or hyporesponsive. Hyperresponsive NK cells mediate significant host cell death and contribute to generating a hyperinflammatory environment. Hyporesponsive NK cell populations shift toward exhaustion and often fail to limit viral pathogenesis, possibly enabling viral persistence. Several emerging therapeutic approaches aimed at addressing NK cell dysregulation have arisen in the last three decades in the setting of cancer and may prove to hold promise in treating viral diseases. However, the application of such therapeutics to treat viral infections remains critically underexplored. This review briefly explores several therapeutic approaches, including the administration of TGF-β inhibitors, immune checkpoint inhibitors, adoptive NK cell therapies, CAR NK cells, and NK cell engagers among other therapeutics.

Facts and Hopes in Colorectal Cancer Immunotherapy

Although a minority of colorectal cancers exhibit mismatch repair deficiency and associated sensitivity to immune checkpoint inhibitors (ICI), the vast majority of colorectal cancers arise in a tolerogenic microenvironment with mismatch repair proficiency, low tumor-intrinsic immunogenicity, and negligible immunotherapy responsiveness. Treatment strategies to augment tumor immunity with combination ICIs and chemotherapy have broadly failed in mismatch repair-proficient tumors. Similarly, although several small single-arm studies have shown that checkpoint blockade plus radiation or select tyrosine kinase inhibition may show improved outcomes compared with historical controls, this finding has not been clearly validated in randomized trials. An evolving next generation of intelligently engineered checkpoint inhibitors, bispecific T-cell engagers, and emerging CAR-T cell therapies may improve immunorecognition of colorectal tumors. Across these modalities, ongoing translational efforts to better define patient populations and biomarkers associated with immune response, as well as combine biologically sound and mutually amplifying therapies, show promise for a new era of immunotherapy in colorectal cancer.

Fc-Engineered Therapeutic Antibodies: Recent Advances and Future Directions

Monoclonal therapeutic antibodies have revolutionized the treatment of cancer and other diseases. Fc engineering aims to enhance the effector functions or half-life of therapeutic antibodies by modifying their Fc regions. Recent advances in the Fc engineering of modern therapeutic antibodies can be considered the next generation of antibody therapy. Various strategies are employed, including altering glycosylation patterns via glycoengineering and introducing mutations to the Fc region, thereby enhancing Fc receptor or complement interactions. Further, Fc engineering strategies enable the generation of bispecific IgG-based heterodimeric antibodies. As Fc engineering techniques continue to evolve, an expanding portfolio of Fc-engineered antibodies is advancing through clinical development, with several already approved for medical use. Despite the plethora of Fc-based mutations that have been analyzed in in vitro and in vivo models, we focus here in this review on the relevant Fc engineering strategies of approved therapeutic antibodies to finetune effector functions, to modify half-life and to stabilize asymmetric bispecific IgGs.

A novel bispecific antibody dual-targeting approach for enhanced neutralization against fast-evolving SARS-CoV-2 variants

Introduction

The emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has caused unprecedented health and socioeconomic crises, necessitating the immediate development of highly effective neutralizing antibodies. Despite recent advancements in anti-SARS-CoV-2 receptor-binding domain (RBD)-specific monoclonal antibodies (mAbs) derived from convalescent patient samples, their efficacy against emerging variants has been limited. In this study, we present a novel dual-targeting strategy using bispecific antibodies (bsAbs) that specifically recognize both the SARS-CoV-2 RBD and fusion peptide (FP), crucial domains for viral attachment to the host cell membrane and fusion in SARS-CoV-2 infection.

Methods

Using phage display technology, we rapidly isolated FP-specific mAbs from an established human recombinant antibody library, identifying K107.1 with a nanomolar affinity for SARS-CoV-2 FP. Furthermore, we generated K203.A, a new bsAb built in immunoglobulin G4-(single-chain variable fragment)2 forms and demonstrating a high manufacturing yield and nanomolar affinity to both the RBD and FP, by fusing K102.1, our previously reported RBD-specific mAb, with K107.1.

Results

Our comprehensive in vitro functional analyses revealed that the K203.A bsAb significantly outperformed the parental RBD-specific mAb in terms of neutralization efficacy against SARS-CoV-2 variants. Furthermore, intravenous monotherapy with K203.A demonstrated potent in vivo neutralizing activity without significant in vivo toxicity in a mouse model infected with a SARS-CoV-2 variant.

Conclusion

These findings present a novel bsAb dual-targeting strategy, directed at SARS-CoV-2 RBD and FP, as an effective approach for rapid development and management against continuously evolving SARS-CoV-2 variants.

Evaluation of the Potential Impact of In Silico Humanization on VHH Dynamics

Camelids have the peculiarity of having classical antibodies composed of heavy and light chains as well as single-chain antibodies. They have lost their light chains and one heavy-chain domain. This evolutionary feature means that their terminal heavy-chain domain, VH, called VHH here, has no partner and forms an independent domain. The VHH is small and easy to express alone; it retains thermodynamic and interaction properties. Consequently, VHHs have garnered significant interest from both biotechnological and pharmaceutical perspectives. However, due to their origin in camelids, they cannot be used directly on humans. A humanization step is needed before a possible use. However, changes, even in the constant parts of the antibodies, can lead to a loss of quality. A dedicated tool, Llamanade, has recently been made available to the scientific community. In a previous paper, we already showed the different types of VHH dynamics. Here, we have selected a representative VHH and tested two humanization hypotheses to accurately assess the potential impact of these changes. This example shows that despite the non-negligible change (1/10th of residues) brought about by humanization, the effect is not drastic, and the humanized VHH retains conformational properties quite similar to those of the camelid VHH.

Construction of IgG-Fab2 bispecific antibody via intein-mediated protein trans-splicing reaction

A bispecific antibody (bsAb) is a class of engineered antibody molecules that simultaneously binds to two different antigens by having two kinds of antigen-binding domains. One of the major obstacles for the bsAb production is the incorrect chain-pairing problem, wherein each heavy and light chain should form pairings with the correct counterpart's chains, but the structural similarity of the incorrect partners also forms the incorrect pairings. This study aimed to demonstrate a bsAb construction method using intein-mediated protein trans-splicing to create IgG-Fab2-type bsAbs, which is a modified antibody with a structure in which two additional Fabs are linked to the N-terminus of the heavy chain of an IgG molecule. The chain-paring problem between a heavy chain and a light chain is circumvented by separate expression and purification of the IgG part and the Fab part. We found that the deletion of a possible glycosylation residue improved the reaction yield and side-reaction cleavage in the protein ligation step. The resulting bsAb, IgG-Fab2 (Her2/CD3), demonstrated target binding activity and cytotoxicity mediated by activated T cells. These results indicate that the use of the protein ligation to produce the IgG-Fab2 type bsAb will expand the bsAb production method.

Immunotherapy: a promising approach for glioma treatment

Gliomas are the most prevalent primary malignant brain tumors worldwide, with glioblastoma (GBM) being the most common and aggressive type. Despite two decades of relentless pursuit in exploring novel therapeutic approaches for GBM, there is limited progress in improving patients' survival outcomes. Numerous obstacles impede the effective treatment of GBM, including the immunosuppressive tumor microenvironment (TME), the blood-brain barrier, and extensive heterogeneity. Despite these challenges, immunotherapies are emerging as a promising avenue that may offer new hope for the treatment of gliomas. There are four main types of immunotherapies for gliomas, immune checkpoint blockades, chimeric antigen receptor T-cell therapies, vaccines, and oncolytic viruses. In addition, gene therapy, bispecific antibody therapy, and combine therapy are also briefly introduced in this review. The significant role of TME in the process of immunotherapies has been emphasized in many studies. Although immunotherapy is a promising treatment for gliomas, enormous effort is required to overcome the existing barriers to its success. Owing to the rapid development and increasing attention paid to immunotherapies for gliomas, this article aims to review the recent advances in immunotherapies for gliomas.

Targeting LAG-3, TIM-3, and TIGIT for cancer immunotherapy

In one decade, immunotherapy based on immune checkpoint blockades (ICBs) has become a new pillar of cancer treatment following surgery, radiation, chemotherapy, and targeted therapies. However, not all cancer patients benefit from single or combination therapy with anti-CTLA-4 and anti-PD-1/PD-L1 monoclonal antibodies. Thus, an increasing number of immune checkpoint proteins (ICPs) have been screened and their effectiveness evaluated in preclinical and clinical trials. Lymphocyte activation gene-3 (LAG-3), T cell immunoglobulin and mucin-domain-containing-3 (TIM-3), and T cell immunoreceptor with immunoglobulin and tyrosine-based inhibitory motif (ITIM) domain (TIGIT) constitute the second wave of immunotherapy targets that show great promise for use in the treatment of solid tumors and leukemia. To promote the research and clinical application of ICBs directed at these targets, we summarize their discovery, immunotherapy mechanism, preclinical efficiency, and clinical trial results in this review.

State-of-the-Art Approaches to Heterologous Expression of Bispecific Antibodies Targeting Solid Tumors

Bispecific antibodies (bsAbs) are some of the most promising biotherapeutics due to the versatility provided by their structure and functional features. bsAbs simultaneously bind two antigens or two epitopes on the same antigen. Moreover, they are capable of directing immune effector cells to cancer cells and delivering various compounds (radionuclides, toxins, and immunologic agents) to the target cells, thus offering a broad spectrum of clinical applications. Current review is focused on the technologies used in bsAb engineering, current progress and prospects of these antibodies, and selection of various heterologous expression systems for bsAb production. We also discuss the platforms development of bsAbs for the therapy of solid tumors.

Antigen presentation in cancer - mechanisms and clinical implications for immunotherapy

Over the past decade, the emergence of effective immunotherapies has revolutionized the clinical management of many types of cancers. However, long-term durable tumour control is only achieved in a fraction of patients who receive these therapies. Understanding the mechanisms underlying clinical response and resistance to treatment is therefore essential to expanding the level of clinical benefit obtained from immunotherapies. In this Review, we describe the molecular mechanisms of antigen processing and presentation in tumours and their clinical consequences. We examine how various aspects of the antigen-presentation machinery (APM) shape tumour immunity. In particular, we discuss genomic variants in HLA alleles and other APM components, highlighting their influence on the immunopeptidomes of both malignant cells and immune cells. Understanding the APM, how it is regulated and how it changes in tumour cells is crucial for determining which patients will respond to immunotherapy and why some patients develop resistance. We focus on recently discovered molecular and genomic alterations that drive the clinical outcomes of patients receiving immune-checkpoint inhibitors. An improved understanding of how these variables mediate tumour-immune interactions is expected to guide the more precise administration of immunotherapies and reveal potentially promising directions for the development of new immunotherapeutic approaches.