Engineering a tumor-selective prodrug T-cell engager bispecific antibody for safer immunotherapy.

T-cell engaging (TCE) bispecific antibodies are potent drugs that trigger the immune system to eliminate cancer cells, but administration can be accompanied by toxic side effects that limit dosing. TCEs function by binding to cell surface receptors on T cells, frequently CD3, with one arm of the bispecific antibody while the other arm binds to cell surface antigens on cancer cells. On-target, off-tumor toxicity can arise when the target antigen is also present on healthy cells. The toxicity of TCEs may be ameliorated through the use of pro-drug forms of the TCE, which are not fully functional until recruited to the tumor microenvironment. This can be accomplished by masking the anti-CD3 arm of the TCE with an autoinhibitory motif that is released by tumor-enriched proteases. Here, we solve the crystal structure of the antigen-binding fragment of a novel anti-CD3 antibody, E10, in complex with its epitope from CD3 and use this information to engineer a masked form of the antibody that can activate by the tumor-enriched protease matrix metalloproteinase 2 (MMP-2). We demonstrate with binding experiments and in vitro T-cell activation and killing assays that our designed prodrug TCE is capable of tumor-selective T-cell activity that is dependent upon MMP-2. Furthermore, we demonstrate that a similar masking strategy can be used to create a pro-drug form of the frequently used anti-CD3 antibody SP34. This study showcases an approach to developing immune-modulating therapeutics that prioritizes safety and has the potential to advance cancer immunotherapy treatment strategies.

The Immunotherapy of Acute Myeloid Leukemia: A Clinical Point of View.

The potential of the immune system to eradicate leukemic cells has been consistently demonstrated by the Graft vs. Leukemia effect occurring after allo-HSCT and in the context of donor leukocyte infusions. Various immunotherapeutic approaches, ranging from the use of antibodies, antibody-drug conjugates, bispecific T-cell engagers, chimeric antigen receptor (CAR) T-cells, and therapeutic infusions of NK cells, are thus currently being tested with promising, yet conflicting, results. This review will concentrate on various types of immunotherapies in preclinical and clinical development, from the point of view of a clinical hematologist. The most promising therapies for clinical translation are the use of bispecific T-cell engagers and CAR-T cells aimed at lineage-restricted antigens, where overall responses (ORR) ranging from 20 to 40% can be achieved in a small series of heavily pretreated patients affected by refractory or relapsing leukemia. Toxicity consists mainly in the occurrence of cytokine-release syndrome, which is mostly manageable with step-up dosing, the early use of cytokine-blocking agents and corticosteroids, and myelosuppression. Various cytokine-enhanced natural killer products are also being tested, mainly as allogeneic off-the-shelf therapies, with a good tolerability profile and promising results (ORR: 20-37.5% in small trials). The in vivo activation of T lymphocytes and NK cells via the inhibition of their immune checkpoints also yielded interesting, yet limited, results (ORR: 33-59%) but with an increased risk of severe Graft vs. Host disease in transplanted patients. Therefore, there are still several hurdles to overcome before the widespread clinical use of these novel compounds.

Corrigendum: Innovative retargeted oncolytic herpesvirus against nectin4-positive cancers.

[This corrects the article DOI: 10.3389/fmolb.2023.1149973.].

Decrease in Heparan Sulphate Binding in Tropism-Retargeted Oncolytic Herpes Simplex Virus (ReHV) Delays Blood Clearance and Improves Systemic Anticancer Efficacy.

The role of the interaction with cell-surface glycosaminoglycans (GAGs) during in vivo HSV infection is currently unknown. The rationale of the current investigation was to improve the anticancer efficacy of systemically administered retargeted oHSVs (ReHVs) by decreasing their binding to GAGs, including those of endothelial cells, blood cells, and off-tumor tissues. As a proof-of-principle approach, we deleted seven amino acids critical for interacting with GAGs from the glycoprotein C (gC) of R-337 ReHV. The modification in the resulting R-399 recombinant prolonged the half-life in the blood of systemically administered R-399 and enhanced its biodistribution to tumor-positive lungs and to the tumor-negative liver. Ultimately, it greatly increased the R-399 efficacy against metastatic-like lung tumors upon IV administration but not against subcutaneous tumors upon IT administration. These results provide evidence that the increased efficacy seen upon R-399 systemic administration correlated with the slower clearance from the circulation. To our knowledge, this is the first in vivo evidence that the partial impairment of the gC interaction with GAGs resulted in a prolonged half-life of circulating ReHV, an increase in the amount of ReHV taken up by tissues and tumors, and, ultimately, an enhanced anticancer efficacy of systemically administered ReHV.

[Possibilities of «therapeutic retargeting¼ of 3-hydroxypyridine and succinic acid derivatives due to their dopaminergic action]. / Vozmozhnosti «terapevticheskogo perenatselivaniya¼ proizvodnykh 3-oksipiridina i yantarnoi kisloty, obuslovlennye ikh dofaminergicheskim deistviem.

The review is devoted to a comparative analysis of the clinical efficacy of the original domestic derivatives of 3-hydroxypyridine and succinic acid (emoxipine, reamberin and mexidol) in comparison with the results of an experimental study of their dopaminergic action. The position that the dopaminomimetic activity of emoxipin, reamberin and mexidol largely determines their anti-ischemic, antihypoxic, insulin-potentiating neuroprotective, nootropic and antidepressant potential has been substantiated. A comparative analysis of the safety profile of emoxipine, reamberin and mexidol was carried out, taking into account potential and real side-effects caused by iatrogenic deviations from the eudopaminergic state. It has been shown that mexidol (2-ethyl-6-methyl-3-hydroxypyridine succinate), which is simultaneously a derivative of 3-hydroxypyridine and succinic acid, has the best balance of efficacy and safety. A generalized assessment of the available data on the successful use of off-label derivatives of 3-hydroxypyridine and succinic acid indicates the advisability of a significant expansion of indications for their clinical use. The authors resume that the «therapeutic retargeting¼ of emoxipin, reamberin and mexidol (i.e. their use for qualitatively new indications) will contribute to progress in the treatment of socially significant and most common diseases.

Topologically associating domains define the impact of de novo promoter variants on autism spectrum disorder risk.

Whole-genome sequencing (WGS) studies of autism spectrum disorder (ASD) have demonstrated the roles of rare promoter de novo variants (DNVs). However, most promoter DNVs in ASD are not located immediately upstream of known ASD genes. In this study analyzing WGS data of 5,044 ASD probands, 4,095 unaffected siblings, and their parents, we show that promoter DNVs within topologically associating domains (TADs) containing ASD genes are significantly and specifically associated with ASD. An analysis considering TADs as functional units identified specific TADs enriched for promoter DNVs in ASD and indicated that common variants in these regions also confer ASD heritability. Experimental validation using human induced pluripotent stem cells (iPSCs) showed that likely deleterious promoter DNVs in ASD can influence multiple genes within the same TAD, resulting in overall dysregulation of ASD-associated genes. These results highlight the importance of TADs and gene-regulatory mechanisms in better understanding the genetic architecture of ASD.

CAR-Aptamers Enable Traceless Enrichment and Monitoring of CAR-Positive Cells and Overcome Tumor Immune Escape.

Chimeric antigen receptor (CAR)-positive cell therapy, specifically with anti-CD19 CAR-T (CAR19-T) cells, achieves a high complete response during tumor treatment for hematological malignancies. Large-scale production and application of CAR-T therapy can be achieved by developing efficient and low-cost enrichment methods for CAR-T cells, expansion monitoring in vivo, and overcoming tumor escape. Here, novel CAR-specific binding aptamers (CAR-ap) to traceless sort CAR-positive cells and obtain a high positive rate of CAR19-T cells is identified. Additionally, CAR-ap-enriched CAR19-T cells exhibit similar antitumor capacity as CAR-ab (anti-CAR antibody)-enriched CAR-T cells. Moreover, CAR-ap accurately monitors the expansion of CAR19-T cells in vivo and predicts the prognosis of CAR-T treatment. Essentially, a novel class of stable CAR-ap-based bispecific circular aptamers (CAR-bc-ap) is constructed by linking CAR-ap with a tumor surface antigen (TSA): protein tyrosine kinase 7 (PTK7) binding aptamer Sgc8. These CAR-bc-aps significantly enhance antitumor cytotoxicity with a loss of target antigens by retargeting CAR-T cells to the tumor in vitro and in vivo. Overall, novel CAR-aptamers are screened for traceless enrichment, monitoring of CAR-positive cells, and overcoming tumor cell immune escape. This provides a low-cost and high-throughput approach for CAR-positive cell-based immunotherapy.

Curriculum-based humanoid robot identification using large-scale human motion database.

Identifying an accurate dynamics model remains challenging for humanoid robots. The difficulty is mainly due to the following two points. First, a good initial model is required to evaluate the feasibility of motions for data acquisition. Second, a highly nonlinear optimization problem needs to be solved to design movements to acquire the identification data. To cope with the first point, in this paper, we propose a curriculum of identification to gradually learn an accurate dynamics model from an unreliable initial model. For the second point, we propose using a large-scale human motion database to efficiently design the humanoid movements for the parameter identification. The contribution of our study is developing a humanoid identification method that does not require the good initial model and does not need to solve the highly nonlinear optimization problem. We showed that our curriculum-based approach was able to more efficiently identify humanoid model parameters than a method that just randomly picked reference motions for identification. We evaluated our proposed method in a simulation experiment and demonstrated that our curriculum was led to obtain a wide variety of motion data for efficient parameter estimation. Consequently, our approach successfully identified an accurate model of an 18-DoF, simulated upper-body humanoid robot.

Efficacy of Systemically Administered Retargeted Oncolytic Herpes Simplex Viruses-Clearance and Biodistribution in Naïve and HSV-Preimmune Mice.

We investigated the anticancer efficacy, blood clearance, and tissue biodistribution of systemically administered retargeted oncolytic herpes simplex viruses (ReHVs) in HSV-naïve and HSV-preimmunized (HSV-IMM) mice. Efficacy was tested against lung tumors formed upon intravenous administration of cancer cells, a model of metastatic disease, and against subcutaneous distant tumors. In naïve mice, HER2- and hPSMA-retargeted viruses, both armed with mIL-12, were highly effective, even when administered to mice with well-developed tumors. Efficacy was higher for combination regimens with immune checkpoint inhibitors. A significant amount of infectious virus persisted in the blood for at least 1 h. Viral genomes, or fragments thereof, persisted in the blood and tissues for days. Remarkably, the only sites of viral replication were the lungs of tumor-positive mice and the subcutaneous tumors. No replication was detected in other tissues, strengthening the evidence of the high cancer specificity of ReHVs, a property that renders ReHVs suitable for systemic administration. In HSV-IMM mice, ReHVs administered at late times failed to exert anticancer efficacy, and the circulating virus was rapidly inactivated. Serum stability and in vivo whole blood stability assays highlighted neutralizing antibodies as the main factor in virus inactivation. Efforts to deplete mice of the neutralizing antibodies are ongoing.

Rational selection of an ideal oncolytic virus to address current limitations in clinical translation.

Oncolytic virus therapy (OVT) is a promising modality that leverages the propensity of natural or engineered viruses to selectively replicate in and kill cancer cells. Over the past decade, (pre)clinical studies have focused on the development and testing of adenovirus, herpes simplex virus, and vaccinia virus-based vectors. These studies have identified barriers to success confronting the field. Here, we propose a set of selection criteria or ideal properties of a successful oncolytic virus, which include lack of pathogenicity, low seroprevalence, selectivity (infection and replication), transgene carrying capacity, and genome stability. We use these requirements to analyze the oncolytic virus landscape, and then identify a potentially optimal species for platform development - vesicular stomatitis virus.

Innovative retargeted oncolytic herpesvirus against nectin4-positive cancers.

Nectin4 is a recently discovered tumor associated antigen expressed in cancers that constitute relevant unmet clinical needs, including the undruggable triple negative breast cancer, pancreatic ductal carcinoma, bladder/urothelial cancer, cervical cancer, lung carcinoma and melanoma. So far, only one nectin4-specific drug-Enfortumab Vedotin-has been approved and the clinical trials that test novel therapeutics are only five. Here we engineered R-421, an innovative retargeted onco-immunotherapeutic herpesvirus highly specific for nectin4 and unable to infect through the natural herpes receptors, nectin1 or herpesvirus entry mediator. In vitro, R-421 infected and killed human nectin4-positive malignant cells and spared normal cells, e.g., human fibroblasts. Importantly from a safety viewpoint, R-421 failed to infect malignant cells that do not harbor nectin4 gene amplification/overexpression, whose expression level was moderate-to-low. In essence, there was a net threshold value below which cells were spared from infection, irrespective of whether they were malignant or normal; the only cells that R-421 targeted were the malignant overexpressing ones. In vivo, R-421 decreased or abolished the growth of murine tumors made transgenic for human nectin4 and conferred sensitivity to immune checkpoint inhibitors in combination therapies. Its efficacy was augmented by the cyclophosphamide immunomodulator and decreased by depletion of CD8-positive lymphocytes, arguing that it was in part T cell-mediated. R-421 elicited in-situ vaccination that protected from distant challenge tumors. This study provides proof-of-principle specificity and efficacy data justifying nectin4-retargeted onco-immunotherapeutic herpesvirus as an innovative approach against a number of difficult-to-drug clinical indications.

Privacy preserving for AI-based 3D human pose recovery and retargeting.

As an essential research task in artificial intelligence (AI), the estimation of 3D human poses has important application value in virtual reality, medical diagnosis, athlete training and other fields. However, human pose recovery and retargeting require the acquisition of detailed visual data containing private information, which has led to increasing concerns about user privacy and security. Therefore, we build a lightweight framework, called Human Motion Parameters Prediction (HMPP), which can infer the 3D mesh and 3D skeletal joint points of the human body while protecting the privacy of the user. The proposed method successfully reduces or suppresses privacy attributes while ensuring important features to perform human pose estimation. The 2D and 3D joints are used for supervision to improve the interpretability of the model at each stage. In addition, the prediction of the camera's internal parameters is added so that the model can be augmented with projection supervision, thereby using more 2D datasets for training and improving the generalization ability of the model. Finally, the predicted motion parameters are used for 3D reconstruction and motion retargeting. Experiments show that our approach can achieve excellent evaluation results on multiple datasets and avoid inadvertently compromising private and sensitive data.

eIg-based bispecific T-cell engagers targeting EGFR: Format matters.

Bispecific antibodies are molecules with versatile modes of action and applications for therapy. They are commonly developed as T-cell engagers (TCE), which simultaneously target an antigen expressed by tumor cells and CD3 expressed by T-cells, thereby inducing T-cell-mediated target cell killing. There is growing evidence that the molecular composition and valency for the target antigen influence the activity of TCEs. Here, the eIg platform technology was used to generate a set of bispecific TCEs targeting epidermal growth factor receptors (EGFR) and CD3. These molecules either included or lacked an Fc region and exhibited one binding site for CD3 and either one or two binding sites for EGFR (1 + 1 or 2 + 1 formats) utilizing different molecular arrangements of the binding sites. In total, 11 different TCE formats were analyzed for binding to target cells and T cells, T cell-mediated killing of tumor cells, and for the activation of T cells (release of cytokines and proliferation of T-cells). Bivalent binding to EGFR strongly increased binding and T cell-mediated killing. However, the molecular composition and position of the CD3-binding arm also affected target cell killing, cytokine release, and T-cell proliferation. Our findings support that screening of a panel of formats is beneficial to identify the most potent bispecific TCE, and that format matters.

Affilin-based retargeting of adenoviral vectors to the epidermal growth factor receptor.

INTRODUCTION: Treatment of head and neck squamous cell carcinomas (HNSCC) by oncolytic adenoviral vectors holds promise as an efficient anti-cancer therapy. The epidermal growth factor receptor (EGFR) represents an attractive target receptor since it is frequently overexpressed in many types of HNSCC. METHODS: To achieve EGFR-specific targeting by human adenovirus type 5 (HAdV-5) based vectors, the EGFR affinity ligand Affilin was covalently attached in a position specific manner either to the fiber or the hexon protein of the vector capsid. In vitro and in vivo studies investigated EGFR-specific cancer cell transduction, susceptibility to natural sequestration mechanisms, pharmacokinetics and biodistribution profiles of Affilin-decorated vectors. RESULTS: Affilin-decorated vectors showed strongly enhanced and EGFR-specific cancer cell transduction in vitro and less susceptibility to known sequestration mechanisms of HAdV-5 particles. However, in vivo neither systemic nor intratumoral vector administration resulted in an improved transduction of EGFR-positive tumors. Comprehensive analyses indicated hampered EGFR-targeting by Affilin-decorated vectors was caused by rapid vector particle consumption due to binding to the murine EGFR, insufficient tumor vascularization and poor target accessibility for Affilin in the solid tumor caused by a pronounced tumor stroma. CONCLUSION: In vitro studies yielded proof-of-concept results demonstrating that covalent attachment of a receptor-specific Affilin to the adenoviral capsid provides an effective and versatile tool to address cancer-specific target receptors by adenoviral vectors. Regarding EGFR as the vector target, off-target tissue transduction and low receptor accessibility within the tumor tissue prevented efficient tumor transduction by Affilin-decorated vectors, rendering EGFR a difficult-to-target receptor for adenoviral vectors.

Fiber manipulation and post-assembly nanobody conjugation for adenoviral vector retargeting through SpyTag-SpyCatcher protein ligation.

For adenoviruses (Ads) to be optimally effective in cancer theranostics, they need to be retargeted toward target cells and lose their natural tropism. Typically, this is accomplished by either engineering fiber proteins and/or employing bispecific adapters, capable of bonding Ad fibers and tumor antigen receptors. This study aimed to present a simple and versatile method for generating Ad-based bionanoparticles specific to target cells, using the SpyTag-SpyCatcher system. The SpyTag peptide was inserted into the HI loop of fiber-knob protein, which could act as a covalent anchoring site for a targeting moiety fused to a truncated SpyCatcher (SpyCatcherΔ) pair. After confirming the presence and functionality of SpyTag on the Ad type-5 (Ad5) fiber knob, an adapter molecule, comprising of SpyCatcherΔ fused to an anti-vascular endothelial growth factor receptor 2 (VEGFR2) nanobody, was recombinantly expressed in Escherichia coli and purified before conjugation to fiber-modified Ad5 (fmAd5). After evaluating fmAd5 detargeting from its primary coxsackie and adenovirus receptor (CAR), the nanobody-decorated fmAd5 could be efficiently retargeted to VEGFR2-expressing 293/KDR and human umbilical vein endothelial (HUVEC) cell lines. In conclusion, a plug-and-play platform was described in this study for detargeting and retargeting Ad5 through the SpyTag-SpyCatcher system, which could be potentially applied to generate tailored bionanoparticles for a broad range of specific targets; therefore, it can be introduced as a promising approach in cancer nanotheranostics.

3D Pose Estimation and Tracking in Handball Actions Using a Monocular Camera.

Player pose estimation is particularly important for sports because it provides more accurate monitoring of athlete movements and performance, recognition of player actions, analysis of techniques, and evaluation of action execution accuracy. All of these tasks are extremely demanding and challenging in sports that involve rapid movements of athletes with inconsistent speed and position changes, at varying distances from the camera with frequent occlusions, especially in team sports when there are more players on the field. A prerequisite for recognizing the player's actions on the video footage and comparing their poses during the execution of an action is the detection of the player's pose in each element of an action or technique. First, a 2D pose of the player is determined in each video frame, and converted into a 3D pose, then using the tracking method all the player poses are grouped into a sequence to construct a series of elements of a particular action. Considering that action recognition and comparison depend significantly on the accuracy of the methods used to estimate and track player pose in real-world conditions, the paper provides an overview and analysis of the methods that can be used for player pose estimation and tracking using a monocular camera, along with evaluation metrics on the example of handball scenarios. We have evaluated the applicability and robustness of 12 selected 2-stage deep learning methods for 3D pose estimation on a public and a custom dataset of handball jump shots for which they have not been trained and where never-before-seen poses may occur. Furthermore, this paper proposes methods for retargeting and smoothing the 3D sequence of poses that have experimentally shown a performance improvement for all tested models. Additionally, we evaluated the applicability and robustness of five state-of-the-art tracking methods on a public and a custom dataset of a handball training recorded with a monocular camera. The paper ends with a discussion apostrophizing the shortcomings of the pose estimation and tracking methods, reflected in the problems of locating key skeletal points and generating poses that do not follow possible human structures, which consequently reduces the overall accuracy of action recognition.

Pseudotyping Bacteriophage P2 Tail Fibers to Extend the Host Range for Biomedical Applications.

Bacteriophages (phages) represent powerful potential treatments against antibiotic-resistant bacterial infections. Antibiotic-resistant bacteria represent a significant threat to global health, with an estimated 70% of infection-causing bacteria being resistant to one or more antibiotics. Developing novel antibiotics against the limited number of cellular targets is expensive and time-consuming, and bacteria can rapidly develop resistance. While bacterial resistance to phage can evolve, bacterial resistance to phage does not appear to spread through lateral gene transfer, and phage may similarly adapt through mutation to recover infectivity. Phages have been identified for all known bacteria, allowing the strain-selective killing of pathogenic bacteria. Here, we re-engineered the Escherichia coli phage P2 to alter its tropism toward pathogenic bacteria. Chimeric tail fibers formed between P2 and S16 genes were designed and generated through two approaches: homology- and literature-based. By presenting chimeric P2:S16 fibers on the P2 particle, our data suggests that the resultant phages were effectively detargeted from the native P2 cellular target, lipopolysaccharide, and were instead able to infect via the proteinaceous receptor, OmpC, the natural S16 receptor. Our work provides evidence that pseudotyping P2 is feasible and can be used to extend the host range of P2 to alternative receptors. Extension of this work could produce alternative chimeric tail fibers to target pathogenic bacterial threats. Our engineering of P2 allows adsorption through a heterologous outer-membrane protein without culturing in its native host, thus providing a potential means of engineering designer phages against pathogenic bacteria from knowledge of their surface proteome.

Nanobody-based retargeting of an oncolytic herpesvirus for eliminating CXCR4+ GBM cells: A proof of principle.

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, which remains difficult to cure. The very high recurrence rate has been partly attributed to the presence of GBM stem-like cells (GSCs) within the tumors, which have been associated with elevated chemokine receptor 4 (CXCR4) expression. CXCR4 is frequently overexpressed in cancer tissues, including GBM, and usually correlates with a poor prognosis. We have created a CXCR4-retargeted oncolytic herpesvirus (oHSV) by insertion of an anti-human CXCR4 nanobody in glycoprotein D of an attenuated HSV-1 (ΔICP34.5, ΔICP6, and ΔICP47), thereby describing a proof of principle for the use of nanobodies to target oHSVs toward specific cellular entities. Moreover, this virus has been armed with a transgene expressing a soluble form of TRAIL to trigger apoptosis. In vitro, this oHSV infects U87MG CXCR4+ and patient-derived GSCs in a CXCR4-dependent manner and, when armed, triggers apoptosis. In a U87MG CXCR4+ orthotopic xenograft mouse model, this oHSV slows down tumor growth and significantly improves mice survival. Customizing oHSVs with diverse nanobodies for targeting multiple proteins appears as an interesting approach for tackling the heterogeneity of GBM, especially GSCs. Altogether, our study must be considered as a proof of principle and a first step toward personalized GBM virotherapies to complement current treatments.

The eIg technology to generate Ig-like bispecific antibodies.

Bispecific antibodies have emerged as therapeutic molecules with a multitude of modes of action and applications. Here, we present a novel approach to solve the light-chain problem for the generation of bispecific Ig-like antibodies using the second constant domain of IgE (EHD2) genetically modified to force heterodimerization. This was achieved by introducing a C14S mutation in one domain and a C102S mutation in the other domain, which removed of one of the crossover disulfide bonds. Substituting the CH1 and CL domains of an antigen binding fragment (Fab) with these heterodimerizing EHD2 (hetEHD2) domains resulted in Fab-like building blocks (eFab). These eFabs were used to generate different bispecific antibodies of varying valency and molecular composition employing variable domains with different specificities and from different origins. Formats included bivalent bispecific IgG-like molecules (eIgs) and Fc-less Fab-eFab fusion proteins, as well as tri- and tetravalent Fab-eIg fusion proteins. All proteins, including bispecific antibodies for dual receptor targeting and for retargeting of T cells, efficiently assembled into functional molecules. Furthermore, none of the hetEHD2-comprising molecules showed binding to the two Fcε receptors and are thus most likely do not induce receptor cross-linking and activation. In summary, we established the eIg technology as a versatile and robust platform for the generation of bispecific antibodies of varying valency, geometry, and composition, suitable for numerous applications.Abbreviations: antibody drug conjugate (ADC), acute lymphocytic leukemia (ALL), constant domain of IgE (Cε), receptor of Cε (CεRI or CεRII), cluster of differentiation (CD), constant domain of heavy chain (CH), constant domain of light chain (CL), (single-chain) diabody ((sc)Db), diabody-immunoglobulin (Db-Ig), dynamic light scattering (DLS), Fragment antigen-binding (Fab), Fab with hetEHD2 (eFab), Fab-EHD2 with T121G in chain 1 and S10I in chain 2 (EFab), bispecific Ig domain containing hetEHD2 (eIg), extracellular domain (ECD), epidermal growth factor receptor 1, 2, 3 (EGFR, HER2, HER3), heavy chain domain 2 of IgE (EHD2), EHD2 domain with C102S (EHD2-1), EHD2 domain with C14S and N39Q (EHD2-2), (human or mouse) fragment crystalline ((hu or mo)Fc), heavy chain (HC), heterodimerized second domain of IgE (hetEHD2), high molecular weight (HMW), immunoglobulin (Ig), light chain (LC), liquid chromatography-mass spectrometry (LC-MS), mesenchymal epithelial transition factor (MET), heavy chain domain 2 of IgM (MHD2), peripheral blood mononuclear cell (PBMC), prolactin receptor (PRLP), Stokes radius (RS), single-chain Fragment variable (scFv), tumor necrosis factor (TNF), TNF receptor 2 (TNFR2), single-chain TNF-related apoptosis-inducing ligand (scTRAIL), variable domain of heavy chain (VH), variable domain of light chain (VL).

Bispecific antibodies for immune cell retargeting against cancer.

INTRODUCTION: Following the approval of the T cell engaging bispecific antibody blinatumomab, immune cell retargeting with bispecific or multispecific antibodies has emerged as a promising cancer immunotherapy strategy, offering alternative mechanisms compared to immune checkpoint blockade. As we gain more understanding of the complex tumor microenvironment, rules and design principles have started to take shape on how to best harness the immune system to achieve optimal anti-tumor activities. AREAS COVERED: In the present review, we aim to summarize the most recent advances and challenges in using bispecific antibodies for immune cell retargeting and to provide insights into various aspects of antibody engineering. Discussed herein are studies that highlight the importance of considering antibody engineering parameters, such as binding epitope, affinity, valency, and geometry to maximize the potency and mitigate the toxicity of T cell engagers. Beyond T cell engaging bispecifics, other bispecifics designed to recruit the innate immune system are also covered. EXPERT OPINION: Diverse and innovative molecular designs of bispecific/multispecific antibodies have the potential to enhance the efficacy and safety of immune cell retargeting for the treatment of cancer. Whether or not clinical data support these different hypotheses, especially in solid tumor settings, remains to be seen.