Logic-gated antibody pairs that selectively act on cells co-expressing two antigens

Engineering Agonistic Bispecifics to Investigate the Influence of Distance on Surface-Mediated Complement Activation

The development of agonists capable of activating the human complement system by binding to the C1 complex presents a novel approach for targeted cell killing. Bispecific nanobodies and Abs can successfully use C1 for this purpose; however, efficacy varies significantly between epitopes, Ab type, and bispecific design. To address this variability, we investigated monomeric agonists of C1 in the form of bispecific nanobodies, which lack Fc domains that lead to oligomerization in Abs. These therefore offer an ideal opportunity to explore the geometric parameters crucial for C1 activation. In this study, we explored the impact of linker length as a metric for Ag and epitope location. DNA nanotechnology and protein engineering allowed us to design linkers with controlled lengths and flexibilities, revealing a critical range of end-to-end distances for optimal complement activation. We discovered that differences in complement activation were not caused by differential C1 activation or subsequent cleavage of C4, but instead impacted C4b deposition and downstream membrane lysis. Considering the importance of Ab class and subclass, this study provides insights into the structural requirements of C1 binding and activation, highlighting linker and hinge engineering as a potential strategy to enhance potency over specific cellular targets. Additionally, using DNA nanotechnology to modify geometric parameters demonstrated the potential for synthetic biology in complement activation. Overall, this research offers valuable insights into the design and optimization of agonists for targeted cell killing through complement activation.

Cancer therapy with antibodies

The greatest challenge in cancer therapy is to eradicate cancer cells with minimal damage to normal cells. Targeted therapy has been developed to meet that challenge, showing a substantially increased therapeutic index compared with conventional cancer therapies. Antibodies are important members of the family of targeted therapeutic agents because of their extraordinarily high specificity to the target antigens. Therapeutic antibodies use a range of mechanisms that directly or indirectly kill the cancer cells. Early antibodies were developed to directly antagonize targets on cancer cells. This was followed by advancements in linker technologies that allowed the production of antibody-drug conjugates (ADCs) that guide cytotoxic payloads to the cancer cells. Improvement in our understanding of the biology of T cells led to the production of immune checkpoint-inhibiting antibodies that indirectly kill the cancer cells through activation of the T cells. Even more recently, bispecific antibodies were synthetically designed to redirect the T cells of a patient to kill the cancer cells. In this Review, we summarize the different approaches used by therapeutic antibodies to target cancer cells. We discuss their mechanisms of action, the structural basis for target specificity, clinical applications and the ongoing research to improve efficacy and reduce toxicity.

The present and future of bispecific antibodies for cancer therapy

Bispecific antibodies (bsAbs) enable novel mechanisms of action and/or therapeutic applications that cannot be achieved using conventional IgG-based antibodies. Consequently, development of these molecules has garnered substantial interest in the past decade and, as of the end of 2023, 14 bsAbs have been approved: 11 for the treatment of cancer and 3 for non-oncology indications. bsAbs are available in different formats, address different targets and mediate anticancer function via different molecular mechanisms. Here, we provide an overview of recent developments in the field of bsAbs for cancer therapy. We focus on bsAbs that are approved or in clinical development, including bsAb-mediated dual modulators of signalling pathways, tumour-targeted receptor agonists, bsAb-drug conjugates, bispecific T cell, natural killer cell and innate immune cell engagers, and bispecific checkpoint inhibitors and co-stimulators. Finally, we provide an outlook into next-generation bsAbs in earlier stages of development, including trispecifics, bsAb prodrugs, bsAbs that induce degradation of tumour targets and bsAbs acting as cytokine mimetics.

Tumor Microenvironment Remodeling-Mediated Sequential Drug Delivery Potentiates Treatment Efficacy

Toll-like receptor 7/8 agonists, such as imidazoquinolines (IMDQs), are promising for the de novo priming of antitumor immunity. However, their systemic administration is severely limited due to the off-target toxicity. Here, this work describes a sequential drug delivery strategy. The formulation is composed of two sequential modules: a tumor microenvironment remodeling nanocarrier (poly(l-glutamic acid)-graft-methoxy poly(ethylene glycol)/combretastatin A4, termed CA4-NPs) and an immunotherapy nanocarrier (apcitide peptide-decorated poly(l-glutamic acid)-graft-IMDQ-N3 conjugate, termed apcitide-PLG-IMDQ-N3 ). CA4-NPs, as a vascular disrupting agent, are utilized to remodel the tumor microenvironment for enhancing tumor coagulation and hypoxia. Subsequently, the apcitide-PLG-IMDQ-N3 could identify and target tumor coagulation through the binding of surface apcitide peptide to the GPIIb-IIIa on activated platelets. Afterward, IMDQ is activated selectively through the conversion of "-N3 " to "-NH2 " in the presence of hypoxia. The biodistribution results confirm their high tumor uptake of activated IMDQ (22.66%ID/g). By augmenting the priming and immunologic memory of tumor-specific CD8+ T cells, 4T1 and CT26 tumors with a size of ≈500 mm3 are eradicated without recurrence in mouse models.

Flow cytometry: Aspects and application in plant and biological science

Flow cytometry is a potent method that enables the quick and concurrent investigation of several characteristics of single cells in solution. Photodiodes or photomultiplier tubes are employed to detect the dispersed and fluorescent light signals that are produced by the laser beam as it passes through the cells. Photodetectors transform the light signals produced by the laser into electrical impulses. A computer then analyses these electrical impulses to identify and measure the various cell populations depending on their fluorescence or light scattering characteristics. Based on their fluorescence or light scattering properties, cell populations can be examined and/or isolated. This review covers the basic principle, components, working and specific biological applications of flow cytometry, including studies on plant, cell and molecular biology and methods employed for data processing and interpretation as well as the potential future relevance of this methodology in light of retrospective analysis and recent advancements in flow cytometry.

Impact of structural modifications of IgG antibodies on effector functions

Immunoglobulin G (IgG) antibodies are a critical component of the adaptive immune system, binding to and neutralizing pathogens and other foreign substances. Recent advances in molecular antibody biology and structural protein engineering enabled the modification of IgG antibodies to enhance their therapeutic potential. This review summarizes recent progress in both natural and engineered structural modifications of IgG antibodies, including allotypic variation, glycosylation, Fc engineering, and Fc gamma receptor binding optimization. We discuss the functional consequences of these modifications to highlight their potential for therapeutical applications.

Cell surface sculpting using logic-gated protein actuators

Cell differentiation and tissue specialization lead to unique cellular surface landscapes and exacerbated or loss of expression patterns can result in further heterogenicity distinctive of pathological phenotypes1-3. Immunotherapies and emerging protein therapeutics seek to exploit such differences by engaging cell populations selectively based on their surface markers. Since a single surface antigen rarely defines a specific cell type4,5, the development of programmable molecular systems that integrate multiple cell surface features to convert on-target inputs to user-defined outputs is highly desirable. Here, we describe an autonomous decision-making protein device driven by proximity-gated protein trans-splicing that allows local generation of an active protein from two otherwise inactive fragments. We show that this protein actuator platform can perform various Boolean logic operations on cell surfaces, allowing highly selective recruitment of enzymatic and cytotoxic activities to specific cells within mixed populations. Due to its intrinsic modularity and tunability, this technology is expected to be compatible with different types of inputs, targeting modalities and functional outputs, and as such will have broad application in the synthetic biology and biotechnology areas.

Improving the tumor selectivity of T cell engagers by logic-gated dual tumor-targeting

Targeting single tumor antigens makes it difficult to provide sufficient tumor selectivity for T cell engagers (TCEs), leading to undesirable toxicity and even treatment failure, which is particularly serious in solid tumors. Here, we designed novel trispecific TCEs (TriTCEs) to improve the tumor selectivity of TCEs by logic-gated dual tumor-targeting. TriTCE can effectively redirect and activate T cells to kill tumor cells (~18 pM EC₅₀) by inducing the aggregation of dual tumor antigens, which was ~70- or 750- fold more effective than the single tumor-targeted isotype controls, respectively. Further in vivo experiments indicated that TriTCE has the ability to accumulate in tumor tissue and can induce circulating T cells to infiltrate into tumor sites. Hence, TriTCE showed a stronger tumor growth inhibition ability and significantly prolonged the survival time of the mice. Finally, we revealed that this concept of logic-gated dual tumor-targeted TriTCE can be applied to target different tumor antigens. Cumulatively, we reported novel dual tumor-targeted TriTCEs that can mediate a robust T cell response by simultaneous recognition of dual tumor antigens at the same cell surface. TriTCEs allow better selective T cell activity on tumor cells, resulting in safer TCE treatment.

A new dawn for monoclonal antibodies against antimicrobial resistant bacteria

Antimicrobial resistance (AMR) is a quickly advancing threat for human health worldwide and almost 5 million deaths are already attributable to this phenomenon every year. Since antibiotics are failing to treat AMR-bacteria, new tools are needed, and human monoclonal antibodies (mAbs) can fill this role. In almost 50 years since the introduction of the first technology that led to mAb discovery, enormous leaps forward have been made to identify and develop extremely potent human mAbs. While their usefulness has been extensively proved against viral pathogens, human mAbs have yet to find their space in treating and preventing infections from AMR-bacteria and fully conquer the field of infectious diseases. The novel and most innovative technologies herein reviewed can support this goal and add powerful tools in the arsenal of weapons against AMR.

A Tool, an App and a Field: Fluorescent PET Sensors, Blood Electrolyte Analysis and Molecular Logic as Products of Supramolecular Photoscience from Northern Ireland and Sri Lanka

The general tool of fluorescent PET (photoinduced electron transfer) sensors/switches - a molecular design principle with engineering features - is outlined, with the aid of frontier orbital energy diagrams. Fluorophores such as anthracene, 1,3-diaryl-Δ² -pyrazolines and 4-amino-1,8-naphthalimides are employed within this system, alongside receptors such as amines, carboxylates, crown ethers and amino acids. This tool appealed to a multinational corporation for building a medical analyzer for electrolytes such as Na⁺ , K⁺ , Ca²⁺ and gases like CO₂ , which became a commercially successful application. Finally, the tool was a springboard for chemistry to cross into computer science. The field of molecular logic can elucidate how molecules inside us handle information. Molecular examples of the simplest logic gates such as YES, NOT, OR, AND are described. A case of a human-level computation - visual edge detection - is also included.