Multi-specific antibodies for cancer immunotherapy

Orchestrating NK and T cells via tri-specific nano-antibodies for synergistic antitumor immunity

The functions of natural killer (NK) and T cells in innate and adaptive immunity, as well as their functions in tumor eradication, are complementary and intertwined. Here we show that utilization of multi-specific antibodies or nano-antibodies capable of simultaneously targeting both NK and T cells could be a valuable approach in cancer immunotherapy. Here, we introduce a tri-specific Nano-Antibody (Tri-NAb), generated by immobilizing three types of monoclonal antibodies (mAbs), using an optimized albumin/polyester composite nanoparticle conjugated with anti-Fc antibody. This Tri-NAb, targeting PDL1, 4-1BB, and NKG2A (or TIGIT) simultaneously, effectively binds to NK and CD8+ T cells, triggering their activation and proliferation, while facilitating their interaction with tumor cells, thereby inducing efficient tumor killing. Importantly, the antitumor efficacy of Tri-NAb is validated in multiple models, including patient-derived tumor organoids and humanized mice, highlighting the translational potential of NK and T cell co-targeting.

Application of recombinant antibodies for treatment of Clostridioides difficile infection: Current status and future perspective

Clostridioides difficile (C. difficile), known as the major cause of antibiotic-associated diarrhea, is regarded as one of the most common healthcare-associated bacterial infections worldwide. Due to the emergence of hypervirulent strains, development of new therapeutic methods for C. difficile infection (CDI) has become crucially important. In this context, antibodies have been introduced as valuable tools in the research and clinical environments, as far as the effectiveness of antibody therapy for CDI was reported in several clinical investigations. Hence, production of high-performance antibodies for treatment of CDI would be precious. Traditional approaches of antibody generation are based on hybridoma technology. Today, application of in vitro technologies for generating recombinant antibodies, like phage display, is considered as an appropriate alternative to hybridoma technology. These techniques can circumvent the limitations of the immune system and they can be exploited for production of antibodies against different types of biomolecules in particular active toxins. Additionally, DNA encoding antibodies is directly accessible in in vitro technologies, which enables the application of antibody engineering in order to increase their sensitivity and specificity. Here, we review the application of antibodies for CDI treatment with an emphasis on recombinant fragment antibodies. Also, this review highlights the current and future prospects of the aforementioned approaches for antibody-mediated therapy of CDI.

Extending traditional antibody therapies: Novel discoveries in immunotherapy and clinical applications

Immunotherapy has been well regarded as one of the safer and antigen-specific anti-cancer treatments compared to first-generation chemotherapy. Since Coley's discovery, researchers focused on engineering novel antibody-based therapies. Including artificial and modified antibodies, such as antibody fragments, antibody-drug conjugates, and synthetic mimetics, the variety of immunotherapy has been rapidly expanding in the last few decades. Genetic and chemical modifications to monoclonal antibody have been brought into academia, in vivo trials, and clinical applications. Here, we have looked around antibodies overall. First, we elucidate the antibody structure and its cytotoxicity mechanisms. Second, types of therapeutic antibodies are presented. Additionally, there is a summarized list of US Food and Drug Administration (FDA)-approved therapeutic antibodies and recent clinical trials. This review provides a comprehensive overview of both the general function of therapeutic antibodies and a few main variations in development, including recent advent with the proposed mechanism of actions, and we introduce types of therapeutic antibodies, clinical trials, and approved commercial immunotherapeutic drugs.

Biomaterials-Based Delivery of Therapeutic Antibodies for Cancer Therapy

Considerable breakthroughs in the treatment of malignant tumors using antibody drugs, especially immunomodulating monoclonal antibodies (mAbs), have been made in the past decade. Despite technological advancements in antibody design and manufacture, multiple challenges face antibody-mediated cancer therapy, such as instability in vivo, poor tumor penetration, limited response rate, and undesirable off-target cytotoxicity. In recent years, an increasing number of biomaterials-based delivery systems have been reported to enhance the antitumor efficacy of antibody drugs. This review summarizes the advances and breakthroughs in integrating biomaterials with therapeutic antibodies for enhanced cancer therapy. A brief introduction to the principal mechanism of antibody-based cancer therapy is first established, and then various antibody immobilization strategies are provided. Finally, the current state-of-the-art in biomaterials-based antibody delivery systems and their applications in cancer treatment are summarized, highlighting how the delivery systems augment the therapeutic efficacy of antibody drugs. The outlook and perspective on biomaterials-based delivery of antitumor antibodies are also discussed.

Synthetic Antibody Mimics Based on Cancer-Targeting Immunostimulatory Peptides

De novo cancer-targeting immunostimulatory peptides have been designed and developed as synthetic antibody mimics. A series of bifunctional peptides incorporating NKp30-binding and NK-cell-activating domains were synthesized as linear dimers and then extended into branching trimeric peptides by the incorporation of GRP78-targeting and tumor-cell-binding sequences. A selected trimeric peptide from this small set of peptides displayed binding capabilities on GRP78+ HepG2 and A549 target cells. Cell binding diminished in the presence of an anti-GRP78 peptide blocker, thus suggesting GRP78-binding dependence. Similarly, the selected trimeric peptide was also found to exhibit NK cell binding in an NKp30-dependent manner, which translated into NK cell activation as indicated by cytokine secretion. In co-culture, fluorescence microscopy revealed that the target GFP-expressing A549 cells were visibly associated with the effector NK cells when pre-activated with lead trimeric peptide. Accordingly, A549 cells were found to be compromised, as evidenced by the loss of GFP signal and notable detection of early-/late-stage apoptosis. Investigation of the immunological markers related to toxicity revealed detectable secretion of pro-inflammatory cytokines and chemokines, including IFN-γ, TNF-α, and IL-8. Furthermore, administration of peptide-activated NK cells into A549-tumor-bearing mice resulted in a consistent decrease in tumor growth when compared to the untreated control group. Taken together, the identification of a lead trimeric peptide capable of targeting and activating NK cells' immunotoxicity directly towards GRP78+ /B7H6- tumors provides a novel proof-of-concept for the development of cancer-targeting immunostimulatory peptide ligands that mimic antibody-targeting and -activating functions related to cancer immunotherapy applications.

Stoichiometry of multi-specific immune checkpoint RNA Abs for T cell activation and tumor inhibition using ultra-stable RNA nanoparticles

Immunotherapy has become a revolutionary subject in cancer therapy during the past few years. Immune checkpoint-targeting antibodies (Abs) could boost anticancer immune responses. However, certain protein-based immunotherapies revealed side effects and unfavorable biodistribution, so effective non-protein options with lower side effects are highly sought after. RNA's ability to form various three-dimensional configurations allows for the creation of a variety of ligands to bind different cell receptors. The rubber-like properties of RNA nanoparticles (NPs) allow for swift lodging to cancer vasculature with little accumulation in vital organs, resulting in a favorable pharmacokinetic/pharmacodynamic (PK/PD) profile and safe pharmacological parameters. Multi-specific drugs are expected to be the fourth wave of biopharmaceutical innovation. Herein, we report the development of multi-specific Ab-like RNA NPs carrying multiple ligands for immunotherapy. The stoichiometries and stereo conformations of the checkpoint-activating RNA NPs were optimized for T cell activation. When compared to mono- and bi-specific RNA NPs, the tri-specific Ab-like RNA NPs bound to the trimeric T cell receptor with the highest efficiency, showed the optimal T cell activation, and promoted the strongest anti-tumor function of immune cells. Animal trials demonstrated that the tri-specific RNA NPs inhibited cancer growth. This Ab-like RNA NP platform represents an alternative to protein Abs for tumor immunotherapy.

Cancer immunotherapy: dawn of the death of cancer?

Cancer is one of the proficient evaders of the immune system which claims millions of lives every year. Developing therapeutics against cancer is extremely challenging as cancer involves aberrations in self, most of which are not detected by the immune system. Conventional therapeutics like chemotherapy, radiotherapy are not only toxic but they significantly lower the quality of life. Immunotherapy, which gained momentum in the 20th century, is emerging as one of the alternatives to the conventional therapies and is relatively less harmful but more costly. This review explores the modern advances in an array of such therapies and try to compare them along with a limited analysis of concerns associated with them.

Characterization of a Novel Bispecific Antibody That Activates T Cells In Vitro and Slows Tumor Growth In Vivo

Although CD3 T cell redirecting antibodies have been successfully utilized for the treatment of hematological malignancies (blinatumomab), the T cell signaling pathways induced by these molecules are incompletely understood. To gain insight into the mechanism of action for T cell redirection antibodies, we created a novel murine CD3xEpCAM bispecific antibody that incorporates a silent Fc to dissect function and signaling of murine CD8 OT1 T cells upon stimulation. T cell-mediated cytotoxicity, cytokine secretion, expression of activation markers, and proliferation were directly induced in T cells treated with the novel CD3xEpCAM bispecific molecule in vitro in the presence of epithelial cell adhesion molecule (EpCAM) expressing tumor cells. Nanostring analysis showed that CD3xEpCAM induced a gene expression profile that resembled antigen-mediated activation, although the magnitude was lower than that of the antigen-induced response. In addition, this CD3xEpCAM bispecific antibody exhibited in vivo efficacy. This is the first study that investigates both in vitro and in vivo murine CD8 T cell function and signaling induced by a CD3xEpCAM antibody having a silent Fc to delineate differences between antigen-independent and antigen-specific T cell activation. These findings expand the understanding of T cell function and signaling induced by CD3 redirection bispecific antibodies and may help to develop more efficacious CD3 redirection therapeutics for cancer treatment, particularly for solid tumors.

Nanoparticles modified by triple single chain antibodies for MRI examination and targeted therapy in pancreatic cancer

Precise diagnosis and effective treatment are crucial to the prognosis of pancreatic ductal adenocarcinoma (PDAC). Magnetic iron oxide nanoparticles (IONPs) are superior magnetic resonance imaging (MRI) contrast agents, while antibodies are significant immunotherapy reagents. Herein, we firstly generated a novel nanocomposite combining triple single chain antibodies (scAbs) and IONPs for the detection and treatment of PDAC.

METHODS

Triple scAbs (scAbMUC4, scAbCEACAM6, scFvCD44v6, MCC triple scAbs) were conjugated to the surface of polyethylene glycol modified IONPs (IONPs-PEG), forming the IONPs-PEG-MCC triple scAbs nanocomposite. Characterization of the nanocomposite was performed, and its cytotoxicity, specificity, and apoptosis induction were evaluated. In vivo MRI study and anti-pancreatic cancer effect assessment were performed in tumor-bearing nude mice.

RESULTS

The size of the IONPs-PEG-MCC triple scAbs nanocomposite was about 23.6 nm. The nanocomposite was non-toxic to normal pancreatic ductal epithelial cells, and could specifically bind to and be internalized by MUC4/CEACAM6/CD44v6-expressing PDAC cells. With an r2 relaxivity of 104.2 mM^-1 s^-1, the IONPs-PEG-MCC triple scAbs nanocomposite could significantly shorten the MRI T2-weighted signal intensity both in vitro and in vivo. The IONPs-PEG-MCC triple scAbs nanocomposite also showed a favorable anti-pancreatic cancer effect.

CONCLUSION

In the present study, the IONPs-PEG-MCC triple scAbs nanocomposite was firstly confirmed as a bi-functional nanocomposite in both MRI and treatment, providing its critical clinical transformation potential in PDAC detection and treatment.

Rapid Purification of Human Bispecific Antibodies via Selective Modulation of Protein A Binding

Methods to rapidly generate high quality bispecific antibodies (BsAb) having normal half-lives are critical for therapeutic programs. Here, we identify 3 mutations (T307P, L309Q, and Q311R or “TLQ”) in the Fc region of human IgG1 which disrupt interaction with protein A while enhancing interaction with FcRn. The mutations are shown to incrementally alter the pH at which a mAb elutes from protein A affinity resin. A BsAb comprised of a TLQ mutant and a wild-type IgG1 can be efficiently separated from contaminating parental mAbs by differential protein A elution starting from either a) purified parental mAbs, b) in-supernatant crossed parental mAbs, or c) co-transfected mAbs. We show that the Q311R mutation confers enhanced FcRn interaction in vitro, and Abs harboring either the Q311R or TLQ mutations have serum half-lives as long as wild-type human IgG1. The mutant Abs have normal thermal stability and Fcγ receptor interactions. Together, the results lead to a method for high-throughput generation of BsAbs suitable for in vivo studies.

Modulation of protein A binding allows single-step purification of mouse bispecific antibodies that retain FcRn binding

The increased number of bispecific antibodies (BsAb) under therapeutic development has resulted in a need for mouse surrogate BsAbs. Here, we describe a one-step method for generating highly pure mouse BsAbs suitable for in vitro and in vivo studies. We identify two mutations in the mouse IgG2a and IgG2b Fc region: one that eliminates protein A binding and one that enhances protein A binding by 8-fold. We show that BsAbs harboring these mutations can be purified from the residual parental monoclonal antibodies in one step using protein A affinity chromatography. The structural basis for the effects of these mutations was analyzed by X-ray crystallography. While the mutation that disrupted protein A binding also inhibited FcRn interaction, a bispecific mutant in which one subunit retained the ability to bind protein A could still interact with FcRn. Pharmacokinetic analysis of the serum half-lives of the mutants showed that the mutant BsAb had a serum half-life comparable to a wild-type Ab. The results describe a rapid method for generating panels of mouse BsAbs that could be used in mouse studies.

Novel agents in classical Hodgkin lymphoma

Classical Hodgkin lymphoma (cHL) is the most common hematological malignancy in young adults and can be cured in most cases. However, relapsed and refractory Hodgkin lymphoma, certain patient groups, such as elderly patients, and toxicity of first-line treatment still pose significant challenges. Consequently, new treatment options are needed. Recently, many new treatment concepts have been evaluated in clinical trials. Targeted drug-antibody conjugates and immune checkpoint inhibitors have decisively changed treatment approaches. This review aims to give a comprehensive overview of novel agents in Hodgkin lymphoma that have been recently or are currently being evaluated in clinical trials. In addition to dedicated sections on brentuximab vedotin (BV) and immune checkpoint inhibitors, other emerging substances and concepts are discussed. In doing so, this review compares trial results regarding safety and efficacy. A special focus lies on the effect novel agents will have on the different treatment settings faced by clinicians involved in the treatment of Hodgkin lymphoma.

An update on antibody-based immunotherapies for Clostridium difficile infection

Clostridium difficile continues to be one of the most prevalent hospital-acquired bacterial infections in the developed world, despite the recent introduction of a novel and effective antibiotic agent (fidaxomicin). Alternative approaches under investigation to combat the anaerobic Gram-positive bacteria include fecal transplantation therapy, vaccines, and antibody-based immunotherapies. In this review, we catalog the recent advances in antibody-based approaches under development and in the clinic for the treatment of C. difficile infection. By and large, inhibitory antibodies that recognize the primary C. difficile virulence factors, toxin A and toxin B, are the most popular passive immunotherapies under investigation. We provide a detailed summary of the toxin epitopes recognized by various antitoxin antibodies and discuss general trends on toxin inhibition efficacy. In addition, antibodies to other C. difficile targets, such as surface-layer proteins, binary toxin, motility factors, and adherence and colonization factors, are introduced in this review.

Multiplexing of receptor occupancy measurements for pharmacodynamic biomarker assessment of biopharmaceuticals

Background

Receptor occupancy (RO) assays measure drug target engagement, and are used as pharmacodynamic (PD) biomarkers. RO assays are commonly performed by flow cytometry and often require multiplexing for assessment of multiple PD biomarkers when specimen volumes are limited. We present multiplexed RO assays for an IGF1R‐EGFR bispecific antibody (Bs‐Ab) and a CTLA4‐Ig recombinant fusion protein to demonstrate key considerations for accurate RO assessment.

Methods

RO in cynomolgus monkeys was determined in whole blood using flow cytometry. Free and total receptors were measured using anti‐receptor fluorescence‐labeled detection reagents, competitive and noncompetitive to drug, respectively.

Results

RO of IGF1R was examined as PD for Bs‐Ab, since IGF1R was expressed on blood cells. Multiplexed measurements of free and total IGF1R showed that IGF1R expression measured by total receptor was highly variable, impacting interpretation of free‐IGF1R. Normalization of free‐over‐total IGF1R measurements compensated for variability of receptor expression allowing for accurate RO assessment. RO of CTLA4‐Ig, a recombinant fusion protein targeting CD80 and CD86 receptors, was multiplexed to simultaneously measure target engagements for both receptors. Both RO methods demonstrated specificity of receptor measurements without cross‐reactivity to each other in multiplexed formats. RO methods were used for evaluation of PD activity of Bs‐Ab and CTLA4‐Ig in cynomolgus monkeys. In both cases, RO results showed dose‐dependent target engagement, corresponding well to the pharmacokinetics.

Conclusions

Multiplexed RO methods allowed accurate assessment of PD activity for Bs‐Ab and CTLA4‐Ig, facilitating development of these biopharmaceuticals from preclinical to clinical stages. © 2015 The Authors Cytometry Part B: Clinical Cytometry Published by Wiley Periodicals, Inc.