Bispecific antibodies in cancer therapy: Target selection and regulatory requirements

Successful targeting of multidrug-resistant tumors with bispecific antibodies

Multidrug resistance (MDR) hinders efficacious cancer chemotherapy. Overexpression of the P-glycoprotein (P-gp) efflux pump (EP) on cancer cells is a primary cause of MDR since it expels numerous anticancer drugs. Small molecule intracellular P-gp antagonists have been investigated clinically to redress MDR but have failed primarily due to adverse effects on P-gp in normal tissue. We used a new approach to counteract P-gp with bispecific antibodies (BsAbs) that simultaneously bound P-gp and CD47 in cis on MDR cells but not normal tissue. Affinities of the individual arms of the BsAbs were low enough to minimize normal tissue binding, but, when the two targets were co-located on MDR cancer cells, both arms of the BsAb engaged with effective avidity. Proof-of-concept was shown in three different MDR xenograft tumor models with a non-humanized chimeric BsAb (targeting P-gp and CD47) that potently restored tumor sensitivity to paclitaxel. Fully humanized variants were successfully developed and characterized. Significant anti-tumor efficacy was observed with the BsAbs both when combined with paclitaxel and as single agents in the absence of paclitaxel. Treatment of MDR cancers with BsAbs using this novel approach has several distinct advantages over prior efforts with small molecule antagonists, including 1) invoking a direct immune attack on the tumors, 2) multimodal mechanisms of action, 3) tumor-specific targeting (with reduced toxicity to normal tissue), and 4) broad applicability as single agents and compatibility with other therapeutics.

Bispecific Antibodies in Hematologic and Solid Tumors: Current Landscape and Therapeutic Advances

Bispecific antibodies (bsAbs) have emerged as a novel class of therapeutics, offering a dual-targeting strategy to enhance the therapeutic efficacy of monoclonal antibodies, which is often limited by tumor heterogeneity and the occurrence of resistance mechanisms. By simultaneously engaging two distinct antigens or pathways, bsAbs disrupt multiple signaling cascades simultaneously, preventing escape mechanisms and offering a more durable response. Furthermore, they can optimize immune activation, improving immune cell recruitment strategies. In particular, T-cell engager bsAbs facilitate immune cell-mediated tumor destruction by linking T cells to tumor antigens. Instead, dual immune checkpoint inhibitors (CPIs) enhance immune activation by blocking inhibitory signals. Additionally, bsAbs targeting tumor growth factors or receptor tyrosine kinases offer solutions for overcoming drug resistance in solid tumors. Although bsAbs have shown remarkable success in hematologic malignancies, their expansion into solid tumors faces key challenges, including tumor heterogeneity, limited tumor penetration, and the risk of on-target, off-tumor toxicities. Addressing these challenges requires innovative engineering strategies, optimized delivery mechanisms, and careful patient selection to maximize therapeutic benefit while mitigating adverse effects. The efficacy of bsAbs in clinical trials has led to their approval for both hematologic and solid malignancies, with numerous agents in development. Combination strategies with chemotherapy, targeted agents, and immune CPIs could represent a promising strategy to further expand their potential. As research progresses, bsAbs are expected to play a role in reshaping the future of precision oncology, offering more effective and tailored treatment options.

Dual-filler mixed matrix membrane with covalent-organic framework and nano TiO2/polyether sulfone for efficient antibody purification

With the rapid expansion of antibody drug market, most biopharmaceutical industries urgently need to optimize their downstream purification processes to reduce production costs and improve market competitiveness. In this study, a dual-filler polyether sulfone (PES) mixed matrix membrane (MMM) that combines covalent-organic framework (COF) with nano TiO2 was developed to overcome the drawbacks of conventional protein A based purification methods. Firstly, COF@TiO2 dual-filler was prepared by Schiff base reaction. The proposed dual-filler MMM was fabricated via nonsolvent-induced phase separation (NIPS), followed by functionalization with a Fab-specific affinity peptide (m-EDPW) of trastuzumab through atom-transfer radical-polymerization method. The resulting m-EDPW@COF@TiO2/PES affinity membrane effectively integrates the merits of COF and TiO2 and show synergistic effects, demonstrating satisfactory hydrophilicity, anti-fouling ability (BSA rejection rate: 97.7 %), enrichment recovery (90.8 %), binding capacity for trastuzumab (386.6 mg/g), and long-term stability (∼ 21 days). Particularly, this affinity membrane showed good selectivity and specificity, enabling the successful purification of trastuzumab from spiked HCC1937 cancer cell culture medium with satisfactory purity (~ 97.4 %) and preservation of the antibody secondary structure. This study not only developed a novel affinity membrane with satisfactory antibody separation performance but also opened a new route for developing dual-filler or multi-filler MMM for highly efficient downstream protein purification.

A pilot study to determine the feasibility and safety of pharmacist and nurse driven management of venetoclax ramp-up in patients with chronic lymphocytic leukemia

PurposeVenetoclax-based treatment for chronic lymphocytic leukemia (CLL) can be a logistically burdensome regimen due to extensive required monitoring of tumor lysis syndrome (TLS). The purpose of this study was to evaluate the feasibility and safety of pharmacist and registered nurse (RN) driven management of venetoclax ramp-up in CLL.MethodsThis was a prospective, pilot program for patients receiving venetoclax-based therapy for CLL. Patients had nine weekly visits during the first three cycles of therapy, of which five visits were independently performed by a pharmacist or RN. Laboratory tests to evaluate TLS were ordered and monitored independently by the RN in collaboration with clinicians (physician, nurse practitioner, physician assistant).ResultsThirty CLL patients, median age 67 years, 73% treated in the frontline setting, started venetoclax between May 2022 and January 2023. After the initial three weeks of obinutuzumab treatment, TLS risk prior to venetoclax initiation had improved to low (93%), medium (3%), and high (3%). There was zero incidence of laboratory or clinical TLS by Howard criteria during the venetoclax ramp-up for all patients. Pharmacist and RNs performed 139 independent visits and monitored 197 sets of TLS labs.ConclusionUse of independent pharmacist and RN visits for toxicity checks and TLS monitoring during weekly venetoclax dose ramp-up did not lead to increased incidence of TLS in patients with CLL. These visits increased both access and efficiency within the CLL clinic. This concept has the potential to be applied in other cancer care settings with a variety of treatment regimens.

Investigation and elimination of noncovalent artificial aggregates during non-reduced capillary electrophoresis-sodium dodecyl sulfate analysis of a multi-specific antibody

Capillary electrophoresis-sodium dodecyl sulfate (CE-SDS) is widely used in the biopharmaceutical industry for monitoring purity and analyzing impurities. The accuracy of the method may be compromised by artificial species resulting from sample preparation or electrophoresis separation due to suboptimal conditions. During non-reduced CE-SDS analysis of a multispecific antibody (msAb), named as multispecific antibody C (msAb-C), a cluster of unexpected peaks was observed after the main peak. The corrected peak area ratio of these peaks showed a strong dependence on loaded protein concentration, which affected the accurate assessment of the purity of msAb-C. After investigation, the unexpected peaks were identified as artifacts produced during electrophoresis separation. These artifacts can be mitigated by three different strategies: 1) adding a more hydrophobic surfactant, sodium hexadecyl sulfate (SHS), to the sample and/or sieving gel buffer; 2) reducing the sample loading amount; and 3) increasing the capillary separation temperature to above 40 ℃. We adopted strategy 1) and strategy 3), and successfully developed an optimal non-reduced CE-SDS method for the accurate and reliable purity assessment of msAb-C samples. These strategies of optimizing non-reduced CE-SDS can be used in developing quality control methods for other therapeutic bispecific/multispecific antibodies.

Recent advances in regulating the cell cycle through inhibiting CDKs for cancer treatment

The inhibition of cyclin-dependent kinases (CDKs) is considered a promising strategy for cancer treatment due to their role in cell cycle regulation. However, CDK inhibitors with no selectivity among CDK families have not been approved. A CDK inhibitor with high selectivity for CDK4/6 exhibited significant treatment effects on breast cancer and has become a heavy bomb on the market. Subsequently, resistance gradually decreased the efficacy of selective CDK4/6 inhibitors in breast cancer treatment. In this review, we first introduce the development of selective CDK4/6 inhibitors and then explain the role of CDK2 activation in inducing resistance to CDK4/6 inhibitors. Moreover, we focused on the development of CDK2/4/6 inhibitors and selective CDK2 inhibitors, which will aid in the discovery of novel CDK inhibitors targeting the cell cycle in the future.

NK cell depletion in bispecific antibody therapy is associated with lack of HIV control after ART interruption

HIV infection remains incurable as the virus persists within a latent reservoir of CD4+T cells. Novel approaches to enhance immune responses against HIV are essential for effective control and potential cure of the infection. In this study, we designed a novel tetravalent bispecific antibody (Bi-Ab32/16) to simultaneously target the gp120 viral protein on infected cells, and the CD16a receptor on NK cells. In vitro, Bi-Ab32/16 triggered a potent, specific, and polyfunctional NK-dependent response against HIV-infected cells. Moreover, addition of the Bi-Ab32/16 significantly reduced the latent HIV reservoir after viral reactivation and mediated the clearance of cells harboring intact proviruses in samples from people with HIV (PWH). However, the in vivo preclinical evaluation of Bi-Ab32/16 in humanized mice expressing IL-15 (NSG-Hu-IL-15) revealed a significant decline of NK cells associated with poor virological control after ART interruption. Our study underscores the need to carefully evaluating strategies for sustained NK cell stimulation during ART withdrawal.

Formation of mono- and dual-labelled antibody fragment conjugates via reversible site-selective disulfide modification and proximity induced lysine reactivity

Many protein bioconjugation strategies focus on the modification of lysine residues owing to the nucleophilicity of their amine side-chain, the generally high abundance of lysine residues on a protein's surface and the ability to form robustly stable amide-based bioconjugates. However, the plethora of solvent accessible lysine residues, which often have similar reactivity, is a key inherent issue when searching for regioselectivity and/or controlled loading of an entity. A relevant example is the modification of antibodies and/or antibody fragments, whose conjugates offer potential for a wide variety of applications. Thus, research in this area for the controlled loading of an entity via reaction with lysine residues is of high importance. In this article, we present an approach to achieve this by exploiting the quantitative and reversible site-selective modification of disulfides using pyridazinediones, which facilitates near-quantitative proximity-induced reactions with lysines to enable controlled loading of an entity. The strategy was appraised on several clinically relevant antibody fragments and enabled the formation of mono-labelled lysine-modified antibody fragment conjugates via the formation of stable amide bonds and the use of click chemistry for modular modification. Furthermore, through the use of multiple cycles of this novel strategy, an orthogonally bis-labelled lysine-modified antibody fragment conjugate was also furnished.

Bispecific antibodies as powerful immunotherapeutic agents for urological cancers: Recent innovations based on preclinical and clinical evidence

Conventional immunotherapy has emerged as a key option for cancer treatment. However, its efficacy has been limited in urological cancers, especially prostate cancer, because of the immunosuppressive tumor microenvironment (TME), difficulty in drug delivery, aberrant immune response, and damage to normal cells. Bispecific antibodies (BsAbs) are engineered proteins with two different antigen-binding domains, designed using different technologies and in various formats. BsAb-based tumor immunotherapy has yielded optimistic results in preclinical and clinical investigations of many tumor types, including urological cancers. However, a series of challenges, including tumor heterogeneity, TME, Ab immunogenicity, adverse effects, serum half-life, low response rates, and drug resistance, hamper the application of BsAbs. In this review, we provide insights into the most common BsAb platforms with different mechanisms of action, which are under preclinical and clinical research, along with ways to overcome the challenges in BsAb administration for treating urological cancer.

Structural insights into antibody-based immunotherapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common types of primary liver cancer and remains a leading cause of cancer-related deaths worldwide. While traditional approaches like surgical resection and tyrosine kinase inhibitors struggle against the tumor's immune evasion, monoclonal antibody (mAb)-based immunotherapies have emerged as promising alternatives. Several therapeutic antibodies that counter the immunosuppressive tumor microenvironment have demonstrated efficacy in clinical trials, leading to FDA approvals for advanced HCC treatment. A crucial aspect of advancing these therapies lies in understanding the structural interactions between antibodies and their targets. Recent findings indicate that mAbs and bispecific antibodies (bsAbs) can target different, non-overlapping epitopes on immune checkpoints such as PD-1 and CTLA-4. This review delves into the epitope-paratope interactions of structurally unresolved mAbs and bsAbs, and discusses the potential for combination therapies based on their non-overlapping epitopes. By leveraging this unique feature, combination therapies could enhance immune activation, reduce resistance, and improve overall efficacy, marking a new direction for antibody-based immunotherapy in HCC.

Bispecific antibodies and CLEM: an analytical approach to advanced cell imaging for therapeutic strategies

The development of bispecific antibodies (BsAbs) represents a significant advancement in therapeutic antibody design, enabling the simultaneous targeting of two different antigens. This dual-targeting capability enhances therapeutic efficacy, particularly in complex diseases like cancer, where tumor heterogeneity presents a significant challenge for traditional treatments. By bridging two distinct pathways, BsAbs can improve specificity and minimize off-target effects, making them invaluable in therapeutic contexts. Integrating advanced imaging techniques, particularly Correlative Light and Electron Microscopy (CLEM), offers a unique opportunity to visualize the dynamic interactions of BsAbs within cellular environments. CLEM combines the strengths of optical and electron microscopy, allowing researchers to observe real-time antibody-antigen interactions at nanoscale resolution. This synergy not only deepens our understanding of BsAbs' mechanisms of action but also provides critical insights into their spatial distribution, binding kinetics, and functional dynamics in live cells. In this review, the integration of BsAbs and CLEM paves the way for targeted therapeutic strategies, fostering the development of more effective treatments that can adapt to the complexities of disease pathology.

Present and future of cancer nano-immunotherapy: opportunities, obstacles and challenges

Clinically, multimodal therapies are adopted worldwide for the management of cancer, which continues to be a leading cause of death. In recent years, immunotherapy has firmly established itself as a new paradigm in cancer care that activates the body's immune defense to cope with cancer. Immunotherapy has resulted in significant breakthroughs in the treatment of stubborn tumors, dramatically improving the clinical outcome of cancer patients. Multiple forms of cancer immunotherapy, including immune checkpoint inhibitors (ICIs), adoptive cell therapy and cancer vaccines, have become widely available. However, the effectiveness of these immunotherapies is not much satisfying. Many cancer patients do not respond to immunotherapy, and disease recurrence appears to be unavoidable because of the rapidly evolving resistance. Moreover, immunotherapies can give rise to severe off-target immune-related adverse events. Strategies to remove these hindrances mainly focus on the development of combinatorial therapies or the exploitation of novel immunotherapeutic mediations. Nanomaterials carrying anticancer agents to the target site are considered as practical approaches for cancer treatment. Nanomedicine combined with immunotherapies offers the possibility to potentiate systemic antitumor immunity and to facilitate selective cytotoxicity against cancer cells in an effective and safe manner. A myriad of nano-enabled cancer immunotherapies are currently under clinical investigation. Owing to gaps between preclinical and clinical studies, nano-immunotherapy faces multiple challenges, including the biosafety of nanomaterials and clinical trial design. In this review, we provide an overview of cancer immunotherapy and summarize the evidence indicating how nanomedicine-based approaches increase the efficacy of immunotherapies. We also discuss the key challenges that have emerged in the era of nanotechnology-based cancer immunotherapy. Taken together, combination nano-immunotherapy is drawing increasing attention, and it is anticipated that the combined treatment will achieve the desired success in clinical cancer therapy.

Novel PD-L1/VISTA Dual Inhibitor as Potential Immunotherapy Agents

Inhibiting the activity of immune checkpoint proteins to reignite the antitumor activity of immune cells has emerged as a pivotal strategy. PD-L1 and VISTA, as critical proteins governing immune regulation, are concurrently upregulated under conditions such as hypoxia. Through a rational drug design process, P17, a dual-target inhibitor for PD-L1 and VISTA is identified. This inhibitor blocks the signaling pathways of both PD-L1 and VISTA at the protein and cellular levels, thereby reactivating the antitumor function of T cells. P17 displays encouraging attributes in terms of druggability and safety assessments. Notably, P17 demonstrates superior antitumor efficacy compared to single-target inhibitors at equivalent doses in in vivo experiments. More crucially, P17 significantly enhances the infiltration of immune cells. This study not only validates the effectiveness of a dual-target inhibitor strategy against PD-L1 and VISTA, but also identifies P17 as a promising candidate molecule with significant therapeutic potential.

Updates in Head and Neck Oncology - Current Knowledge and Future Horizons

Treatment for head and neck recurrent/metastatic squamous cell carcinoma (HNSCC) with immune checkpoint inhibitors has now become the new therapeutic standard, primarily replacing the EXTREME and TPex protocols that included the EGFR inhibitor Cetuximab and chemotherapy. Even if there are considerable advances in therapeutic results, less than 20% of patients with this stage of the disease survive more than four years. These results demonstrate the need to identify more effective therapies beyond simple PD1/PD-L1 blockade. Antibody-drug conjugates (ADC), vaccines, bispecific kinase inhibitors and fusion proteins involving the modulation of the tumor microenvironment are strategies to be exploited in the future. Also, in locally advanced cancers, the results of combining immunotherapy with chemoradiation treatment did not give the expected results. The use of other therapeutic sequences, including immunotherapy in association with neo-adjuvant chemotherapy, but also the association with mTOR inhibitors are also evaluated in clinical trials. We propose to present some new directions in the therapies of locally advanced relapsed or metastatic HNSCC.

IMM2520, a novel anti-CD47/PD-L1 bispecific antibody for cancer immune therapy

PD-1/PD-L1 is an important signaling pathway in the adaptive immune system. The CD47/SIRPα signaling pathway is a crucial "do not eat me" signal for innate immunity. This study evaluated the anti-tumor mechanism of IMM2520 in vitro and in vivo. IMM2520 was generated using the "mab-trap" platform. IMM2520 showed high affinity to PD-L1 and relatively lower affinity to CD47, displaying preferential binding to PD-L1 on tumor cells. IMM2520 had the potent ability to inhibit the PD-1/PD-L1 and CD47/SIRPα signaling pathways and killed tumor cells through ADCC and ADCP. Importantly, IMM2520 did not bind to human red blood cells or induce erythrocyte agglutination. IMM2520 demonstrated a tendency to bind to CD47+/PD-L1+ tumor cells, reducing its binding to CD47 single-positive cells. In mouse transplantation models, compared with the first-generation CD47/PD-L1 BsAb (IMM2505), IMM2520 exhibited stronger and dose-dependent antitumor activity. These findings imply that IMM2520 may offer a novel therapeutic alternative for cancer patients.

A CD25×TIGIT bispecific antibody induces anti-tumor activity through selective intratumoral Treg cell depletion

Intratumoral regulatory T cells (Tregs) express high levels of CD25 and TIGIT, which are also recognized as markers of effector T cell (Teff) activation. Targeting these molecules each alone with monoclonal antibodies (mAbs) poses a risk of concurrently depleting both Teffs and peripheral Tregs, thereby compromising the effectiveness and selectivity of intratumoral Treg depletion. Here, leveraging the increased abundance of CD25+ TIGIT+ double-positive Tregs in the solid tumor microenvironment (but not in peripheral tissues), we explore the feasibility of using a CD25×TIGIT bispecific antibody (bsAb) to selectively deplete intratumoral Tregs. We initially constructed a bsAb co-targeting mouse CD25 and TIGIT, NSWm7210, and found that NSWm7210 conferred enhanced intratumoral Treg depletion, Teff activation, and tumor suppression as compared to the parental monotherapies in mouse models. We subsequently constructed a bsAb co-targeting human CD25 and TIGIT (NSWh7216), which preferentially eliminated CD25+ TIGIT+ double-positive cells over single-positive cells in vitro. NSWh7216 exhibited enhanced anti-tumor activity without toxicity of peripheral Tregs in CD25 humanized mice compared to the parental monotherapies. Our study illustrates the use of CD25×TIGIT bsAbs as effective agents against solid tumors based on selective depletion of intratumoral Tregs.

Expression, regulation, and function of PD-L1 on non-tumor cells in the tumor microenvironment

Antiprogrammed death ligand 1 (PD-L1) therapy is a leading immunotherapy, but only some patients with solid cancers benefit. Overwhelming evidence has revealed that PD-L1 is expressed on various immune cells in the tumor microenvironment (TME), including macrophages, dendritic cells, and regulatory T cells, modulating tumor immunity and influencing tumor progression. PD-L1 can also be located on tumor cell membranes as well as in exosomes and cytoplasm. Accordingly, the dynamic expression and various forms of PD-L1 might explain the therapy's limited efficacy and resistance. Herein a systematic summary of the expression of PD-L1 on different immune cells and their regulatory mechanisms is provided to offer a solid foundation for future studies.

Future investigative directions for novel therapeutic targets in head and neck cancer

AREAS COVERED

Here we describe novel agents, their mechanism(s) of action, preclinical results, and ongoing clinical trials in HNSCC.

EXPERT OPINION

Established therapeutic targets in HNSCC include EGFR (cetuximab) and PD-1 (pembrolizumab and nivolumab). Despite the detection of many other possible targets in HNSCC cell lines and patient tumors, no other therapies have successfully advanced to date. Identification of predictive biomarkers may guide the use of targeted agents and combination therapies. Clinical trials supported by strong preclinical data in relevant models are more likely to advance treatment options.

Mechanism of Action and Pharmacokinetics of Approved Bispecific Antibodies

Bispecific antibodies represent a significant advancement in therapeutic antibody engineering, offering the ability to simultaneously target two distinct antigens. This dual-targeting capability enhances therapeutic efficacy, especially in complex diseases, such as cancer and autoimmune disorders, where drug resistance and incomplete target coverage are prevalent challenges. Bispecific antibodies facilitate immune cell engagement and disrupt multiple signaling pathways, providing a more comprehensive treatment approach than traditional monoclonal antibodies. However, the intricate structure of bispecific antibodies introduces unique pharmacokinetic challenges, including issues related to their absorption, distribution, metabolism, and excretion, which can significantly affect their efficacy and safety. This review provides an in-depth analysis of the structural design, mechanisms of action, and pharmacokinetics of the currently approved bispecific antibodies. It also highlights the engineering innovations that have been implemented to overcome these challenges, such as Fc modifications and advanced dimerization techniques, which enhance the stability and half-life of bispecific antibodies. Significant progress has been made in bispecific antibody technology; however, further research is necessary to broaden their clinical applications, enhance their safety profiles, and optimize their incorporation into combination therapies. Continuous advancements in this field are expected to enable bispecific antibodies to provide more precise and effective therapeutic strategies for a range of complex diseases, ultimately improving patient outcomes and advancing precision medicine.

Evolving Treatment Landscape for Advanced Esophageal and Gastroesophageal Junction Adenocarcinoma

PURPOSE OF REVIEW

This review highlights advances and recent changes in the treatment paradigm for advanced esophageal adenocarcinoma (EAC) and gastroesophageal junction adenocarcinoma (GEJAC).

RECENT FINDINGS

Chemotherapy remains the backbone of treatment for advanced EAC/GEJAC. New targets/agents include immunotherapy, HER-2, claudin18.2, and FGFR2b, with various mechanisms (CAR-T, bispecific mAB, ADCs) altering the treatment landscape against these targets. The approaches to these targets may act together, in sequence, and even synergistically to improve outcomes. Herein, we review the state of the field, including highlighting ongoing clinical trials and additional emerging agents and approaches.

Bispecific antibody (ABL602 2 + 1) induced bistable acute myeloid leukemia kinetics

ABL602 2 + 1, a bispecific antibody with two distinct domains binding to CLL-1 on leukemias and CD3 on T cells, exhibits superior T cell activation and tumour lysing activity. Treatment outcomes of bispecific antibody rely on acute myeloid leukemia cell replication and antibody induced tumour lysing, but their quantitative relationship was unknown. Mathematical models are employed to quantitatively investigate HL-60 cell kinetics determined by bispecific antibody and tumour burden. First, we analysed cytotoxicity assay data testing HL-60 cell against bispecific antibody and T cells, and found efficiency of bispecific antibody induced tumour lysing increases but saturates with increase of HL-60 cell, T cell and bispecific antibody concentration. As a result, their interaction leads to bistable HL-60 cell kinetics; namely, at a given bispecific antibody and T cell concentration interval, HL-60 cell kinetics with small tumour burdens are inhibited but refractory to large tumour burdens. T cell concentration is strong negatively correlated with HL-60 cell concentration. With bispecific antibody clearance, observed bistable HL-60 cell kinetics still exists. Our finding explains observed phenomenon that bispecific antibody was less efficacious at high tumour burden even with enough activated cytotoxic CD8 + T cells. Maintaining high antibody concentration and preventing T-cell exhaustion are equivalently important to sustain long-term control.

Therapeutic antibodies in oncology: an immunopharmacological overview

The biotechnological development of monoclonal antibodies and their immunotherapeutic use in oncology have grown exponentially in the last decade, becoming the first-line therapy for some types of cancer. Their mechanism of action is based on the ability to regulate the immune system or by interacting with targets that are either overexpressed in tumor cells, released into the extracellular milieu or involved in processes that favor tumor growth. In addition, the intrinsic characteristics of each subclass of antibodies provide specific effector functions against the tumor by activating antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, and antibody-dependent cellular phagocytosis, among other mechanisms. The rational design and engineering of monoclonal antibodies have improved their pharmacokinetic and pharmacodynamic features, thus optimizing the therapeutic regimens administered to cancer patients and improving their clinical outcomes. The selection of the immunoglobulin G subclass, modifications to its crystallizable region (Fc), and conjugation of radioactive substances or antineoplastic drugs may all improve the antitumor effects of therapeutic antibodies. This review aims to provide insights into the immunological and pharmacological aspects of therapeutic antibodies used in oncology, with a rational approach at molecular modifications that can be introduced into these biological tools, improving their efficacy in the treatment of cancer.

Chemical Production of Cytotoxic Bispecific Antibodies Using the Ugi Multicomponent Reaction

Bispecific antibodies (bsAbs) have recently emerged as a promising platform for the treatment of several conditions, most importantly cancer. Based on the combination of two different antigen-binding motifs in a single macromolecule; bsAbs can either display the combined characteristics of their parent antibodies, or new therapeutic features, inaccessible by the sole combination of two distinct antibodies. While bsAbs are traditionally produced by molecular biology techniques, the chemical development of bsAbs holds great promises and strategies have just begun to surface. In this context, we took advantage of a chemical strategy based on the use of the Ugi reaction for the site-selective conjugation of whole antibodies and coupled the resulting conjugates in a bioorthogonal manner with Fab fragments, derived from various antibodies. We thus managed to produce five different bsAbs with 2 : 1 valency, with yields ranging from 20 % to 48 %, and showed that the affinity of the parent antibody was preserved in all bsAbs. We further demonstrated the interest of our strategy by producing two other bsAbs behaving as cytotoxic T cell engagers with IC50 values in the picomolar range in vitro.

Revolutionizing Cancer Treatment: Recent Advances in Immunotherapy

Cancer immunotherapy has emerged as a transformative approach in oncology, utilizing the body's immune system to specifically target and destroy malignant cells. This review explores the scope and impact of various immunotherapeutic strategies, including monoclonal antibodies, chimeric antigen receptor (CAR)-T cell therapy, checkpoint inhibitors, cytokine therapy, and therapeutic vaccines. Monoclonal antibodies, such as Rituximab and Trastuzumab, have revolutionized treatment paradigms for lymphoma and breast cancer by offering targeted interventions that reduce off-target effects. CAR-T cell therapy presents a potentially curative option for refractory hematologic malignancies, although challenges remain in effectively treating solid tumors. Checkpoint inhibitors have redefined the management of cancers like melanoma and lung cancer; however, managing immune-related adverse events and ensuring durable responses are critical areas of focus. Cytokine therapy continues to play a vital role in modulating the immune response, with advancements in cytokine engineering improving specificity and reducing systemic toxicity. Therapeutic vaccines, particularly mRNA-based vaccines, represent a frontier in personalized cancer treatment, aiming to generate robust, long-lasting immune responses against tumor-specific antigens. Despite these advancements, the field faces significant challenges, including immune resistance, tumor heterogeneity, and the immunosuppressive tumor microenvironment. Future research should address these obstacles through emerging technologies, such as next-generation antibodies, Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-based gene editing, and AI-driven drug discovery. By integrating these novel approaches, cancer immunotherapy holds the promise of offering more durable, less toxic, and highly personalized treatment options, ultimately improving patient outcomes and survival rates.

Next-Generation Therapeutic Antibodies for Cancer Treatment: Advancements, Applications, and Challenges

The field of cancer treatment has evolved significantly over the last decade with the emergence of next-generation therapeutic antibodies. Conventional treatments like chemotherapy pose significant challenges, including adverse side effects. Monoclonal antibodies have paved the way for more targeted and effective interventions. The evolution from chimeric to humanized and fully human antibodies has led to a reduction in immunogenicity and enhanced tolerance in vivo. The advent of next-generation antibodies, including bispecific antibodies, nanobodies, antibody-drug conjugates, glyco-engineered antibodies, and antibody fragments, represents a leap forward in cancer therapy. These innovations offer increased potency, adaptability, and reduced drug resistance. Challenges such as target validation, immunogenicity, and high production costs exist. However, technological advancements in antibody engineering techniques provide optimism for addressing these issues. The future promises a paradigm shift, where ongoing research will propel these powerful antibodies to the forefront, revolutionizing the fight against cancer and creating new preventive and curative treatments. This review provides an overview of three next-generation antibody-based molecules, namely bispecific antibodies, antibody-drug conjugates, and nanobodies that have shown promising results in cancer treatment. It discusses the evolution of antibodies from conventional forms to next-generation molecules, along with their applications in cancer treatment, production methods, and associated challenges. The review aims to offer researchers insights into the evolving landscape of next-generation antibody-based cancer therapeutics and their potential to revolutionize treatment strategies.

Effects of molecule hydrophobicity and structural flexibility of appended bispecific antibody on Protein A chromatography

Appended bispecific antibody (aBsAb) with two single chain variable fragments (scFv) linked at the c-terminus of its heavy chains is one of the promising formats in bispecific therapeutics. The presence of hydrophobic and flexible scFv fragments render aBsAb molecules higher molecule hydrophobicity and structural flexibility compared to monoclonal antibody (mAb), thus making its purification more challenging. We set out to investigate how the unique molecular properties of aBsAb affect its performance on Protein A chromatography. We showed that aBsAb has a high propensity for chromatography-induced aggregation due to its high molecule hydrophobicity, and this couldn't be improved by the addition of common chaotropic salts. Moreover, the presence of chaotropic salts, such as arginine hydrochloride (Arg-HCl), retarded aBsAb elution during Protein A chromatography rather than facilitating which was widely observed in mAb Protein A elution. Nevertheless, we were able to overcome the aggregation issue by optimizing elution condition and improved aBsAb purity from 29 % to 93 % in Protein A eluate with a high molecular weight (HMW) species of less than 5 %. We also showed that the high molecular flexibility of aBsAb leads to different hydrodynamic sizes of the aBsAb molecule post Protein A elution, neutralization, and re-acidification, which are pH dependent. This is different from mAbs where their sizes do not change post neutralization even with re-exposure to acid. The above unique observations of aBsAb in Protein A chromatography were clearly explained from the perspectives of its high molecular hydrophobicity and structural flexibility.

Investigation on environmental factors contributing to bispecific antibody stability and the reversal of self-associated aggregates

Bispecific antibodies (bsAbs) hold promises for enhanced therapeutic potential surpassing that of their parental monoclonal antibodies. However, bsAbs pose great challenges in their manufacturing, and one of the common reasons is their susceptibility to aggregation. Building on previous studies demonstrating the functionality and potential manufacturability of Fab-scFv format bsAb, this investigation delved into the impact of environmental factors-such as pH, buffer types, ionic strength, protein concentrations, and temperatures-on its stability and the reversal of its self-associated aggregates. Mildly acidic, low-salt conditions were found optimal, ensuring bsAb stability for 30 days even at elevated temperature of 40 °C. Furthermore, these conditions facilitated the reversal of its self-associated aggregates to monomers during the initial 7-day incubation period. Our findings underscore the robustness and resilience of Fab-scFv format bsAb, further confirming its potential manufacturability despite its current absence as commercial products.

Therapeutic potential of cis-targeting bispecific antibodies

The growing clinical success of bispecific antibodies (bsAbs) has led to rapid interest in leveraging dual targeting in order to generate novel modes of therapeutic action beyond mono-targeting approaches. While bsAbs that bind targets on two different cells (trans-targeting) are showing promise in the clinic, the co-targeting of two proteins on the same cell surface through cis-targeting bsAbs (cis-bsAbs) is an emerging strategy to elicit new functionalities. This includes the ability to induce proximity, enhance binding to a target, increase target/cell selectivity, and/or co-modulate function on the cell surface with the goal of altering, reversing, or eradicating abnormal cellular activity that contributes to disease. In this review, we focus on the impact of cis-bsAbs in the clinic, their emerging applications, and untangle the intricacies of improving bsAb discovery and development.

Safety and clinical activity of JNJ-78306358, a human leukocyte antigen-G (HLA-G) x CD3 bispecific antibody, for the treatment of advanced stage solid tumors

BACKGROUND

JNJ-78306358 is a bispecific antibody that redirects T cells to kill human leukocyte antigen-G (HLA-G)-expressing tumor cells. This dose escalation study evaluated the safety, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of JNJ-78306358 in patients with advanced solid tumors.

METHODS

Adult patients with metastatic/unresectable solid tumors with high prevalence of HLA-G expression were enrolled. Dose escalation was initiated with once-weekly subcutaneous administration with step-up dosing to mitigate cytokine release syndrome (CRS).

RESULTS

Overall, 39 heavily pretreated patients (colorectal cancer: n = 23, ovarian cancer: n = 10, and renal cell carcinoma: n = 6) were dosed in 7 cohorts. Most patients (94.9%) experienced ≥ 1 treatment-emergent adverse events (TEAEs); 87.2% had ≥ 1 related TEAEs. About half of the patients (48.7%) experienced CRS, which were grade 1/2. Nine patients (23.1%) received tocilizumab for CRS. No grade 3 CRS was observed. Dose-limiting toxicities (DLTs) of increased transaminases, pneumonitis and recurrent CRS requiring a dose reduction were reported in 4 patients, coinciding with CRS. No treatment-related deaths reported. No objective responses were noted, but 2 patients had stable disease > 40 weeks. JNJ-78306358 stimulated peripheral T cell activation and cytokine release. Anti-drug antibodies were observed in 45% of evaluable patients with impact on exposure. Approximately half of archival tumor samples (48%) had expression of HLA-G by immunohistochemistry.

CONCLUSION

JNJ-78306358 showed pharmacodynamic effects with induction of cytokines and T cell activation. JNJ-78306358 was associated with CRS-related toxicities including increased transaminases and pneumonitis which limited its dose escalation to potentially efficacious levels. Trial registration number ClinicalTrials.gov (No. NCT04991740).

Unlocking the potential of bispecific ADCs for targeted cancer therapy

Antibody-drug conjugates (ADCs) are biologically targeted drugs composed of antibodies and cytotoxic drugs connected by linkers. These innovative compounds enable precise drug delivery to tumor cells, minimizing harm to normal tissues and offering excellent prospects for cancer treatment. However, monoclonal antibody-based ADCs still present challenges, especially in terms of balancing efficacy and safety. Bispecific antibodies are alternatives to monoclonal antibodies and exhibit superior internalization and selectivity, producing ADCs with increased safety and therapeutic efficacy. In this review, we present available evidence and future prospects regarding the use of bispecific ADCs for cancer treatment, including a comprehensive overview of bispecific ADCs that are currently in clinical trials. We offer insights into the future development of bispecific ADCs to provide novel strategies for cancer treatment.

Bispecific and multispecific antibodies in oncology: opportunities and challenges

Research into bispecific antibodies, which are designed to simultaneously bind two antigens or epitopes, has advanced enormously over the past two decades. Owing to advances in protein engineering technologies and considerable preclinical research efforts, bispecific antibodies are constantly being developed and optimized to improve their efficacy and to mitigate toxicity. To date, >200 of these agents, the majority of which are bispecific immune cell engagers, are in either preclinical or clinical evaluation. In this Review, we discuss the role of bispecific antibodies in patients with cancer, including history and development, as well as innovative targeting strategies, clinical applications, and adverse events. We also discuss novel alternative bispecific antibody constructs, such as those targeting two antigens expressed by tumour cells or cells located in the tumour microenvironment. Finally, we consider future research directions in this rapidly evolving field, including innovative antibody engineering strategies, which might enable more effective delivery, overcome resistance, and thus optimize clinical outcomes.

Stepping forward: T-cell redirecting bispecific antibodies in cancer therapy

T cell-redirecting bispecific antibodies are specifically designed to bind to tumor-associated antigens, thereby engaging with CD3 on the T cell receptor. This linkage between tumor cells and T cells actively triggers T cell activation and initiates targeted killing of the identified tumor cells. These antibodies have emerged as one of the most promising avenues within tumor immunotherapy. However, despite success in treating hematological malignancies, significant advancements in solid tumors have yet to be explored. In this review, we aim to address the critical challenges associated with T cell-redirecting bispecific antibodies and explore novel strategies to overcome these obstacles, with the ultimate goal of expanding the application of this therapy to include solid tumors.

Recent developments in targeting breast cancer stem cells (BCSCs): a descriptive review of therapeutic strategies and emerging therapies

Despite recent advancements in the diagnosis and treatment of breast cancer (BC), patient outcomes in terms of survival, recurrence, and disease progression remain suboptimal. A significant factor contributing to these challenges is the cellular heterogeneity within BC, particularly the presence of breast cancer stem cells (BCSCs). These cells are thought to serve as the clonogenic nexus for new tumor growth, owing to their hierarchical organization within the tumor. This descriptive review focuses on the evolving strategies to target BCSCs, which have become a pivotal aspect of therapeutic development. We explore a variety of approaches, including targeting specific tumor surface markers (CD133 and CD44), transporters, heat shock proteins, and critical signaling pathways like Notch, Akt, Hedgehog, KLF4, and Wnt/β-catenin. Additionally, we discuss the modulation of the tumor microenvironment through the CXCR-12/CXCR4 axis, manipulation of pH levels, and targeting hypoxia-inducible factors, vascular endothelial growth factor, and CXCR1/2 receptors. Further, this review focuses on the roles of microRNA expression, strategies to induce apoptosis and differentiation in BCSCs, dietary interventions, dendritic cell vaccination, oncolytic viruses, nanotechnology, immunotherapy, and gene therapy. We particularly focused on studies reporting identification of BCSCs, their unique properties and the efficacy of various therapeutic modalities in targeting these cells. By dissecting these approaches, we aim to provide insights into the complex landscape of BC treatment and the potential pathways for improving patient outcomes through targeted BCSC therapies.

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.

Anti-PD-L1-Based Bispecific Antibodies Targeting Co-Inhibitory and Co-Stimulatory Molecules for Cancer Immunotherapy

Targeting PD-L1 via monospecific antibodies has shown durable clinical benefits and long-term remissions where patients exhibit no clinical cancer signs for many years after treatment. However, the durable clinical benefits and long-term remissions by anti-PD-L1 monotherapy have been limited to a small fraction of patients with certain cancer types. Targeting PD-L1 via bispecific antibodies (referred to as anti-PD-L1-based bsAbs) which can simultaneously bind to both co-inhibitory and co-stimulatory molecules may increase the durable antitumor responses in patients who would not benefit from PD-L1 monotherapy. A growing number of anti-PD-L1-based bsAbs have been developed to fight against this deadly disease. This review summarizes recent advances of anti-PD-L1-based bsAbs for cancer immunotherapy in patents and literatures, and discusses their anti-tumor efficacies in vitro and in vivo. Over 50 anti-PD-L1-based bsAbs targeting both co-inhibitory and co-stimulatory molecules have been investigated in biological testing or in clinical trials since 2017. At least eleven proteins, such as CTLA-4, LAG-3, PD-1, PD-L2, TIM-3, TIGIT, CD28, CD27, OX40, CD137, and ICOS, are involved in these investigations. Twenty-two anti-PD-L1-based bsAbs are being evaluated to treat various advanced cancers in clinical trials, wherein the indications include NSCLC, SNSCLC, SCLC, PDA, MBNHL, SCCHN, UC, EC, TNBC, CC, and some other malignancies. The released data from clinical trials indicated that most of the anti-PD-L1-based bsAbs were well-tolerated and showed promising antitumor efficacy in patients with advanced solid tumors. However, since the approved and investigational bsAbs have shown much more significant adverse reactions compared to PD-L1 monospecific antibodies, anti-PD-L1-based bsAbs may be further optimized via molecular structure modification to avoid or reduce these adverse reactions.

An evaluation of glofitamab, the first fixed-duration bispecific antibody for relapsed or refractory large B-cell lymphomas

INTRODUCTION

Significant proportion of patients with diffuse large B-cell lymphoma (DLBCL) is refractory or relapse (R/R) after the treatment. The prognosis of this patient cohort remains poor. Novel strategies mainly based on immunotherapy and targeted agents are currently being studied. Glofitamab is novel T-cell-engaging bispecific antibody possessing a 2:1 structure with bivalent CD20 binding. Its safety and efficacy in R/R B-cell non-Hodgkin lymphoma including DLBCL were evaluated in phase I-II NP30179 trial.

AREAS COVERED

The article summarizes the milestones and latest reports on glofitamab development in the field of B-cell lymphoma treatment.

EXPERT OPINION

Recently, phase II part of the NP30179 study and several other reports were published proving glofitamab potential in R/R DLBCL patients. Based on the published data, glofitamab was approved by regulatory authorities worldwide for the monotherapy of R/R DLBCL in conventional time-limited manner. It is readily accessible in case of rapidly progressing disease, and it compares well with other novel treatment options. Its side effects are similar to those of other T-cell-engaging agents and can be mitigated by pretreatment with obinutuzumab or step-up dosing. Its safety profile with manageable toxicities heads the clinical development toward combination strategies and its use in earlier therapeutic phases.

The Future of HER2-Targeted Treatment for Osteosarcoma: Lessons from the Negative Trastuzumab Deruxtecan Results

Human epidermal growth factor receptor 2 (HER2), coded by the proto-oncogene ERBB, is known to be mutated or amplified in various malignant diseases, and many HER2-targeted therapies (including monoclonal antibodies and low-molecular-weight tyrosine kinase inhibitors) have been investigated. HER2 overexpression is observed in ~30% of patients with osteosarcoma, and HER2-targeted therapy for osteosarcoma has also been investigated, along with the prognostic and/or predictive value of HER2. An effective HER2-targeted therapy for osteosarcoma has not been established, however. An antibody-drug conjugate (ADC), i.e., trastuzumab deruxtecan (T-DXd), has been approved for the treatment of HER2-positive malignant diseases such as breast cancer and gastric cancer. T-DXd showed promising efficacy in a tumor-agnostic clinical trial, but even T-DXd did not demonstrate sufficient efficacy against HER2-positive osteosarcoma. In this review, the underlying reasons/mechanisms for the failure of HER2-targeted treatments for osteosarcoma (including T-DXd) are discussed, and the potential and future direction of HER2-targeted therapy is described.

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.