Development of a reliable cell-based reporter gene assay to measure the bioactivity of anti-HER2 therapeutic antibodies

Human epidermal growth factor receptor 2 (HER2) is a key player in the pathogenesis and progression of breast cancer and is currently a primary target for breast cancer immunotherapy. Bioactivity determination is necessary to guarantee the safety and efficacy of therapeutic antibodies targeting HER2. Nevertheless, currently available bioassays for measuring the bioactivity of anti-HER2 mAbs are either not representative or have high variability. Here, we established a reliable reporter gene assay (RGA) based on T47D-SRE-Luc cell line that expresses endogenous HER2 and luciferase controlled by serum response element (SRE) to measure the bioactivity of anti-HER2 antibodies. Neuregulin-1 (NRG-1) can lead to the heterodimerization of HER2 on the cell membrane and induce the expression of downstream SRE-controlled luciferase, while pertuzumab can dose-dependently reverse the reaction, resulting in a good dose-response curve reflecting the activity of the antibody. After optimizing the relevant assay parameters, the established RGA was fully validated based on ICH-Q2 (R1), which demonstrated that the method had excellent specificity, accuracy, precision, linearity, and stability. In summary, this robust and innovative bioactivity determination assay can be applied in the development and screening, release control, biosimilar assessment and stability studies of anti-HER2 mAbs.

In silico analysis of the different variable domain oriented single-chain variable fragment antibody-antigen complexes

Single-chain variable fragment (scFv) antibodies hold great potential as diagnostic tools and therapeutic agents, especially for tumor cells. Since these applications require their production with improved properties, the design strategy of scFvs is crucial for their active, soluble, and high yield expression with high affinity towards their antigens. The order of VL and VH domains is one of the important parameters that affect the expression and binding affinity properties of scFvs. In addition, the optimum order of VL and VH domains could change for each scFv. In the present study, we used computer simulation tools to evaluate the effect of variable domain orientation on structure, stability, interacting residues of scFvs, and binding free energies of scFv-antigen complexes. We selected anti-HER2 scFv, which is specific for human epidermal growth receptor 2 (HER2) overexpressed in breast cancer, and anti-IL-1β scFv against IL-1β which is an important inflammatory biomarker, as model scFvs. Molecular dynamics simulations of the scFv-antigen complexes for 100 ns resulted in stability and compactness for both scFv constructs. Interaction and binding free energies calculated by the Molecular Mechanics-Poisson-Boltzmann Surface Area (MM-PBSA) approach suggested that the relative binding energies of anti-HER2 scFv-VLVH and anti-HER2 scFv-VHVL constructs had similar binding affinity towards HER2, while a relatively more negative binding free energy obtained between anti-IL-1β scFv-VHVL and IL-1β pointed to a higher binding affinity. The in silico approach and the results obtained here could be applied as a guide for future experimental interaction studies for highly specific scFvs used as biotechnological tools.Communicated by Ramaswamy H. Sarma.

Supramolecular Heterodimer Peptides Assembly for Nanoparticles Functionalization

Nanoparticle (NP) surface functionalization with proteins, including monoclonal antibodies (mAbs), mAb fragments, and various peptides, has emerged as a promising strategy to enhance tumor targeting specificity and immune cell interaction. However, these methods often rely on complex chemistry and suffer from batch-dependent outcomes, primarily due to limited control over the protein orientation and quantity on NP surfaces. To address these challenges, a novel approach based on the supramolecular assembly of two peptides is presented to create a heterotetramer displaying VHHs on NP surfaces. This approach effectively targets both tumor-associated antigens (TAAs) and immune cell-associated antigens. In vitro experiments showcase its versatility, as various NP types are biofunctionalized, including liposomes, PLGA NPs, and ultrasmall silica-based NPs, and the VHHs targeting of known TAAs (HER2 for breast cancer, CD38 for multiple myeloma), and an immune cell antigen (NKG2D for natural killer (NK) cells) is evaluated. In in vivo studies using a HER2+ breast cancer mouse model, the approach demonstrates enhanced tumor uptake, retention, and penetration compared to the behavior of nontargeted analogs, affirming its potential for diverse applications.

Site-selective antibody-lipid conjugates for surface functionalization of red blood cells and targeted drug delivery

Displaying antibodies on carrier surfaces facilitates precise targeting and delivery of drugs to diseased cells. Here, we report the synthesis of antibody-lipid conjugates (ALCs) through site-selective acetylation of Lys 248 in human Immunoglobulin G (IgG) and the development of antibody-functionalized red blood cells (immunoRBC) for targeted drug delivery. ImmunoRBC with the HER2-selective antibody trastuzumab displayed on the surface (called Tras-RBC) was constructed following a three-step procedure. First, a peptide-guided, proximity-induced reaction transferred an azidoacetyl group to the ε-amino group of Lys 248 in the Fc domain. Second, the azide-modified IgG was subsequently conjugated with dibenzocyclooctyne (DBCO)-functionalized lipids via strain-promoted azide-alkyne cycloaddition (SPAAC) to result in ALCs. Third, the lipid portion of ALCs was then inserted into the cell membranes, and IgGs were displayed on red blood cells (RBCs) to construct immunoRBCs. We then loaded Tras-RBC with a photosensitizer (PS), Zinc phthalocyanine (ZnPc), to selectively target HER2-overexpressing cells, release ZnPc into cancer cells following photolysis, and induce photodynamic cytotoxicity in the cancer cells. This work showcases assembling immunoRBCs following site-selective lipid conjugation on therapeutic antibodies and the targeted introduction of PS into cancer cells. This method could apply to the surface functionalization of other membrane-bound vesicles or lipid nanoparticles for antibody-directed drug delivery.

Multifunctional Supramolecular Hydrogel Modulated Heterojunction Interface Carrier Transport Engineering Facilitates Sensitive Photoelectrochemical Immunosensing

Highly responsive interface of semiconductor nanophotoelectrochemical materials provides a broad development prospect for the identification of low-abundance cancer marker molecules. This work innovatively proposes an efficient blank WO3/SnIn4S8 heterojunction interface formed by self-assembly on the working electrode for interface regulation and photoregulation. Different from the traditional biomolecular layered interface, a hydrogel layer containing manganese dioxide with a wide light absorption range is formed at the interface after an accurate response to external immune recognition. The formation of the hydrogel layer hinders the effective contact between the heterojunction interface and the electrolyte solution, and manganese dioxide in the hydrogel layer forms a strong competition between the light source and the substrate photoelectric material. The process effectively improves the carrier recombination efficiency at the interface, reduces the interface reaction kinetics and photoelectric conversion efficiency, and thus provides strong support for target identification. Taking advantage of the process, the resulting biosensors are being explored for sensitive detection of human epidermal growth factor receptor 2, with a limit of detection as low as 0.037 pg/mL. Also, this study contributes to the advancement of photoelectrochemical biosensing technology and opens up new avenues for the development of sensitive and accurate analytical tools in the field of bioanalysis.

Epitope binning for multiple antibodies simultaneously using mammalian cell display and DNA sequencing

Epitope binning, an approach for grouping antibodies based on epitope similarities, is a critical step in antibody drug discovery. However, conventional methods are complex, involving individual antibody production. Here, we established Epitope Binning-seq, an epitope binning platform for simultaneously analyzing multiple antibodies. In this system, epitope similarity between the query antibodies (qAbs) displayed on antigen-expressing cells and a fluorescently labeled reference antibody (rAb) targeting a desired epitope is analyzed by flow cytometry. The qAbs with epitope similar to the rAb can be identified by next-generation sequencing analysis of fluorescence-negative cells. Sensitivity and reliability of this system are confirmed using rAbs, pertuzumab and trastuzumab, which target human epidermal growth factor receptor 2. Epitope Binning-seq enables simultaneous epitope evaluation of 14 qAbs at various abundances in libraries, grouping them into respective epitope bins. This versatile platform is applicable to diverse antibodies and antigens, potentially expediting the identification of clinically useful antibodies.

Microfluidic Immunosensor Platform for Sensitive Detection of Human Epidermal Growth Factor Receptor-2 Based on Enhanced Cathode Electrochemiluminescence of Bimetallic Nanoclusters

In this work, a microfluidic immunosensor chip was developed by incorporating microfluidic technology with electrochemiluminescence (ECL) for sensitive detection of human epidermal growth factor receptor-2 (HER2). The immunosensor chip can achieve robust reproducibility in mass production by integrating multiple detection units in a series. Notably, nanoscale materials can be better adapted to microfluidic systems, greatly enhancing the accuracy of the immunosensor chip. Ag@Au NCs closed by glutathione (GSH) were introduced in the ECL microfluidic immunosensor system with excellent and stable ECL performance. The synthesized CeO2-Au was applied as a coreaction promoter in the ECL signal amplification system, which made the result of HER2 detection more reliable. In addition, the designed microfluidic immunosensor chip integrated the biosensing system into a microchip, realizing rapid and accurate detection of HER2 by its high throughput and low usage. The developed short peptide ligand NARKFKG (NRK) achieved an effective connection between the antibody and nanocarrier for improving the detection efficiency of the sensor. The immunosensor chip had better storage stability and sensitivity than traditional detection methods, with a wide detection range from 10 fg·mL-1 to 100 ng·mL-1 and a low detection limit (LOD) of 3.29 fg·mL-1. In general, a microfluidic immunosensor platform was successfully constructed, providing a new idea for breast cancer (BC) clinical detection.

Construction of Switch Modules for CAR-T Cell Treatment Using a Site-Specific Conjugation System

Chimeric antigen receptor T-cell (CAR-T cell) therapy has become a promising treatment option for B-cell hematological tumors. However, few optional target antigens and disease relapse due to loss of target antigens limit the broad clinical applicability of CAR-T cells. Here, we conjugated an antibody (Ab) fusion protein, consisting of an Ab domain and a SpyCatcher domain, with the FITC-SpyTag (FITC-ST) peptide to form a bispecific safety switch module using a site-specific conjugation system. We applied the safety switch module to target CD19, PDL1, or Her2-expressing tumor cells by constructing FMC63 (anti-CD19), antiPDL1, or ZHER (anti-Her2)-FITC-ST, respectively. Those switch modules significantly improved the cytotoxic effects of anti-FITC CAR-T cells on tumor cells. Additionally, we obtained the purified CD8+ T cells by optimizing a shorter version of the CD8-binding aptamer to generate anti-FITC CD8-CAR-T cells, which combined with the CD4-FITC-ST switch module (anti-CD4) to eliminate the CD4-positive tumor cells in vitro and in vivo. Overall, we established a novel safety switch module by site-specific conjugation to enhance the antitumor function of universal CAR-T cells, thereby expanding the application scope of CAR-T therapy and improving its safety and efficacy.

Preparation, Characterization, and Radiolabeling of Anti-HER2 scFv With Technetium Tricarbonyl and Stability Studies

Breast cancer is the most common diagnosed cancer, and the second cause of cancer death among women, worldwide. HER2 overexpression occurred in approximately 15% to 20% of breast cancers. Invasive biopsy method has been used for detection of HER2 overexpression. HER2-targeted imaging via an appropriate radionuclide is a promising method for sensitive and accurate identification of HER2+ primary and metastatic lesions. 99mTc-anti-HER2 scFv can specifically target malignancies and be used for diagnosis of the cancer type and metastasis as well as treatment of breast cancer. We radiolabeled anti-HER2 scFv that was expressed in Escherichia coli and purified through Ni-NTA resin under native condition with 99mTc-tricarbonyl formed from boranocarbonate. HER2-based ELISA, BCA, TLC, and HPLC were used in this study. In the current study, anti-HER2 scFv was lyophilized before radiolabeling. It was found that freeze-drying did not change the binding activity of anti-HER2 scFv to HER2. Results demonstrated direct anti-HER2 scFv radiolabeling by 99mTc-tricarbonyl to hexahistidine sequence (His-tag) without any changes in biological activity and radiochemical purity of around 98%. Stability analysis revealed that 99mTc-anti-HER2 scFv is stable for at least 24 h in PBS buffer, normal saline, human plasma proteins, and histidine solution.

Structural Characterization of Monoclonal Antibodies and Epitope Mapping by FFAP Footprinting

Covalent labeling in combination with mass spectrometry is a powerful approach used in structural biology to study protein structures, interactions, and dynamics. Recently, the toolbox of covalent labeling techniques has been expanded with fast fluoroalkylation of proteins (FFAP). FFAP is a novel radical labeling method that utilizes fluoroalkyl radicals generated from hypervalent Togni reagents for targeting aromatic residues. This report further demonstrates the benefits of FFAP as a new method for structural characterization of therapeutic antibodies and interaction interfaces of antigen-antibody complexes. The results obtained from human trastuzumab and its complex with human epidermal growth factor receptor 2 (HER2) correlate well with previously published structural data and demonstrate the potential of FFAP in structural biology.

Anti-HER2 Immunoliposomes: Antitumor Efficacy Attributable to Targeted Delivery of Anthraquinone-Fused Enediyne

Although natural products are essential sources of small-molecule antitumor drugs, some can exert substantial toxicities, limiting their clinical utility. Anthraquinone-fused enediyne natural products are remarkably potent antitumor drug candidates, and uncialamycin and tiancimycin (TNM) A are under development as antibody-drug conjugates. Herein, a novel drug delivery system is introduced for TNM A using anti-human epidermal growth factor receptor 2 (HER2) immunoliposomes (ILs). Trastuzumab-coated TNM A-loaded ILs (HER2-TNM A-ILs) is engineered with an average particle size of 182.8 ± 2.1 nm and a zeta potential of 1.75 ± 0.12 mV. Compared with liposomes lacking trastuzumab, HER2-TNM A-ILs exhibited selective toxicity against HER2-positive KPL-4 and SKBR3 cells. Coumarin-6, a fluorescent TNM A surrogate, is encapsulated within anti-HER2 ILs; the resultant ILs have enhanced cellular uptake in KPL-4 and SKBR3 cells when compared with control liposomes. Furthermore, ILs loaded with more Cy5.5 accumulated in KPL-4 mouse tumors. A single HER2-TNM A-IL dose (0.02 mg kg-1) suppressed the growth of HER2-positive KPL-4 mouse tumors without apparent toxicity. This study not only provides a straightforward method for the effective delivery of TNM A against HER2-positive breast tumors but also underscores the potential of IL-based drug delivery systems when employing highly potent cytotoxins as payloads.

Implementation of antibody-drug conjugates in HER2-positive solid cancers: Recent advances and future directions

In recent decades, there has been a surge in the approval of monoclonal antibodies for treating a wide range of hematological and solid malignancies. These antibodies exhibit exceptional precision in targeting the surface antigens of tumors, heralding a groundbreaking approach to cancer therapy. Nevertheless, monoclonal antibodies alone do not show sufficient lethality against cancerous cells compared to chemotherapy. Consequently, a new class of anti-tumor medications, known as antibody-drug conjugates (ADCs), has been developed to bridge the divide between monoclonal antibodies and cytotoxic drugs, enhancing their therapeutic potential. ADCs are chemically synthesized by binding tumor-targeting monoclonal antibodies with cytotoxic payloads through linkers that are susceptible to cleavage by intracellular proteases. They combined the accurate targeting of monoclonal antibodies with the potent efficacy of cytotoxic chemotherapy drugs while circumventing systemic toxicity and boasting superior lethality over standalone targeted drugs. The human epidermal growth factor receptor (HER) family, which encompasses HER1 (also known as EGFR), HER2, HER3, and HER4, plays a key role in regulating cellular proliferation, survival, differentiation, and migration. HER2 overexpression in various tumors is one of the most frequently targeted antigens for ADC therapy in HER2-positive cancers. HER2-directed ADCs have emerged as highly promising treatment modalities for patients with HER2-positive cancers. This review focuses on three approved anti-HER2 ADCs (T-DM1, DS-8201a, and RC48) and reviews ongoing clinical trials and failed trials based on anti-HER2 ADCs. Finally, we address the notable challenges linked to ADC development and underscore potential future avenues for tackling these hurdles.

Development and evaluation of a human CD47/HER2 bispecific antibody for Trastuzumab-resistant breast cancer immunotherapy

The treatment for trastuzumab-resistant breast cancer (BC) remains a challenge in clinical settings. It was known that CD47 is preferentially upregulated in HER2+ BC cells, which is correlated with drug resistance to trastuzumab. Here, we developed a novel anti-CD47/HER2 bispecific antibody (BsAb) against trastuzumab-resistant BC, named IMM2902. IMM2902 demonstrated high binding affinity, blocking activity, antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and internalization degradation effects against both trastuzumab-sensitive and trastuzumab-resistant BC cells in vitro. The in vivo experimental data indicated that IMM2902 was more effective than their respective controls in inhibiting tumor growth in a trastuzumab-sensitive BT474 mouse model, a trastuzumab-resistant HCC1954 mouse model, two trastuzumab-resistant patient-derived xenograft (PDX) mouse models and a cord blood (CB)-humanized HCC1954 mouse model. Through spatial transcriptome assays, multiplex immunofluorescence (mIFC) and in vitro assays, our findings provided evidence that IMM2902 effectively stimulates macrophages to generate C-X-C motif chemokine ligand (CXCL) 9 and CXCL10, thereby facilitating the recruitment of T cells and NK cells to the tumor site. Moreover, IMM2902 demonstrated a high safety profile regarding anemia and non-specific cytokines release. Collectively, our results highlighted a novel therapeutic approach for the treatment of HER2+ BCs and this approach exhibits significant anti-tumor efficacy without causing off-target toxicity in trastuzumab-resistant BC cells.

Antibody-dye Conjugates Targeting EGFR and HER2 for the Photoimmunotherapy of Bladder Cancer

BACKGROUND/AIM

Although there are curative treatment options for non-muscle-invasive bladder cancer, the recurrence of this tumor is high. Therefore, novel targeted therapies are needed for the complete removal of bladder cancer cells in stages of localized disease, in order to avoid local recurrence, to spare bladder cancer patients from stressful and expensive treatment procedures and to increase their quality of life and life expectancy. This study tested a new approach for the photoimmunotherapy (PIT) of bladder cancer.

MATERIALS AND METHODS

We generated a cysteine modified recombinant version of the antibody cetuximab targeting the epidermal growth factor receptor (EGFR) on the surface of bladder cancer cells. Then, we coupled the novel photoactivatable phthalocyanine dye WB692-CB1 via a maleimide linker to the free cysteines of the antibody. PIT was performed by incubating bladder cancer cells with the antibody dye conjugate followed by irradiation with visible red light.

RESULTS

The conjugate was able to induce specific cytotoxicity in EGFR-positive bladder cancer cells in a light dose-dependent manner. Enhanced cytotoxicity in RT112 bladder cancer cells was evoked by addition of a second antibody dye conjugate targeting HER2 or by repeated cycles of PIT.

CONCLUSION

Our new antibody dye conjugate targeting EGFR-expressing bladder cancer cells is a promising candidate for the future PIT of bladder cancer patients.

Small-molecule-mediated control of the anti-tumour activity and off-tumour toxicity of a supramolecular bispecific T cell engager

The broader clinical use of bispecific T cell engagers for inducing anti-tumour toxicity is hindered by their on-target off-tumour toxicity and the associated neurotoxicity and cytokine-release syndrome. Here we show that the off-tumour toxicity of a supramolecular bispecific T cell engager binding to the T cell co-receptor CD3 and to the human epidermal growth factor receptor 2 on breast tumour cells can be halted by disengaging the T cells from the tumour cells via the infusion of the small-molecule drug amantadine, which disassembles the supramolecular aggregate. In mice bearing human epidermal growth factor receptor 2-expressing tumours and with a human immune system, high intravenous doses of such a 'switchable T cell nanoengager' elicited strong tumour-specific adaptive immune responses that prevented tumour relapse, while the infusion of amantadine restricted off-tumour toxicity, cytokine-release syndrome and neurotoxicity. Supramolecular chemistry may be further leveraged to control the anti-tumour activity and off-tumour toxicity of bispecific antibodies.

CAR affinity modulates the sensitivity of CAR-T cells to PD-1/PD-L1-mediated inhibition

Chimeric antigen receptor (CAR)-T cell therapy for solid tumors faces significant hurdles, including T-cell inhibition mediated by the PD-1/PD-L1 axis. The effects of disrupting this pathway on T-cells are being actively explored and controversial outcomes have been reported. Here, we hypothesize that CAR-antigen affinity may be a key factor modulating T-cell susceptibility towards the PD-1/PD-L1 axis. We systematically interrogate CAR-T cells targeting HER2 with either low (LA) or high affinity (HA) in various preclinical models. Our results reveal an increased sensitivity of LA CAR-T cells to PD-L1-mediated inhibition when compared to their HA counterparts by using in vitro models of tumor cell lines and supported lipid bilayers modified to display varying PD-L1 densities. CRISPR/Cas9-mediated knockout (KO) of PD-1 enhances LA CAR-T cell cytokine secretion and polyfunctionality in vitro and antitumor effect in vivo and results in the downregulation of gene signatures related to T-cell exhaustion. By contrast, HA CAR-T cell features remain unaffected following PD-1 KO. This behavior holds true for CD28 and ICOS but not 4-1BB co-stimulated CAR-T cells, which are less sensitive to PD-L1 inhibition albeit targeting the antigen with LA. Our findings may inform CAR-T therapies involving disruption of PD-1/PD-L1 pathway tailored in particular for effective treatment of solid tumors.

A nanowell platform to identify, sort and expand high antibody-producing cells

Increased use of therapeutic monoclonal antibodies and the relatively high manufacturing costs fuel the need for more efficient production methods. Here we introduce a novel, fast, robust, and safe isolation platform for screening and isolating antibody-producing cell lines using a nanowell chip and an innovative single-cell isolation method. An anti-Her2 antibody producing CHO cell pool was used as a model. The platform; (1) Assures the single-cell origin of the production clone, (2) Detects the antibody production of individual cells and (3) Isolates and expands the individual cells based on their antibody production. Using the nanowell platform we demonstrated an 1.8-4.5 increase in anti-Her2 production by CHO cells that were screened and isolated with the nanowell platform compared to CHO cells that were not screened. This increase was also shown in Fed-Batch cultures where selected high production clones showed titers of 19-100 mg/L on harvest day, while the low producer cells did not show any detectable anti-Her2 IgG production. The screening of thousands of single cells is performed under sterile conditions and the individual cells were cultured in buffers and reagents without animal components. The time required from seeding a single cell and measuring the antibody production to fully expanded clones with increased Her-2 production was 4-6 weeks.

Heterodimerization of T cell engaging bispecific antibodies to enhance specificity against pancreatic ductal adenocarcinoma

BACKGROUND

EGFR and/or HER2 expression in pancreatic cancers is correlated with poor prognoses. We generated homodimeric (EGFRxEGFR or HER2xHER2) and heterodimeric (EGFRxHER2) T cell-engaging bispecific antibodies (T-BsAbs) to direct polyclonal T cells to these antigens on pancreatic tumors.

METHODS

EGFR and HER2 T-BsAbs were constructed using the 2 + 2 IgG-[L]-scFv T-BsAbs format bearing two anti-CD3 scFvs attached to the light chains of an IgG to engage T cells while retaining bivalent binding to tumor antigens with both Fab arms. A Fab arm exchange strategy was used to generate EGFRxHER2 heterodimeric T-BsAb carrying one Fab specific for EGFR and one for HER2. EGFR and HER2 T-BsAbs were also heterodimerized with a CD33 control T-BsAb to generate 'tumor-monovalent' EGFRxCD33 and HER2xCD33 T-BsAbs. T-BsAb avidity for tumor cells was studied by flow cytometry, cytotoxicity by T-cell mediated 51Chromium release, and in vivo efficacy against cell line-derived xenografts (CDX) or patient-derived xenografts (PDX). Tumor infiltration by T cells transduced with luciferase reporter was quantified by bioluminescence.

RESULTS

The EGFRxEGFR, HER2xHER2, and EGFRxHER2 T-BsAbs demonstrated high avidity and T cell-mediated cytotoxicity against human pancreatic ductal adenocarcinoma (PDAC) cell lines in vitro with EC50s in the picomolar range (0.17pM to 18pM). They were highly efficient in driving human polyclonal T cells into subcutaneous PDAC xenografts and mediated potent T cell-mediated anti-tumor effects. Both EGFRxCD33 and HER2xCD33 tumor-monovalent T-BsAbs displayed substantially reduced avidity by SPR when compared to homodimeric EGFRxEGFR or HER2xHER2 T-BsAbs (∼150-fold and ∼6000-fold respectively), tumor binding by FACS (8.0-fold and 63.6-fold), and T-cell mediated cytotoxicity (7.7-fold and 47.2-fold), while showing no efficacy against CDX or PDX. However, if either EGFR or HER2 was removed from SW1990 by CRISPR-mediated knockout, the in vivo efficacy of heterodimeric EGFRxHER2 T-BsAb was lost.

CONCLUSION

EGFR and HER2 were useful targets for driving T cell infiltration and tumor ablation. Two arm Fab binding to either one or both targets was critical for robust anti-tumor effect in vivo. By engaging both targets, EGFRxHER2 heterodimeric T-BsAb exhibited potent anti-tumor effects if CDX or PDX were EGFR+HER2+ double-positive with the potential to spare single-positive normal tissue.

[In vitro and in vivo validation of cytotoxicity of targeting human epidermal growth factor receptor-2 chimeric antigen receptor T (HER2-CAR-T) cells]

Objective To evaluate the toxicology of targeting human epidermal growth factor receptor-2 chimeric antigen receptor T (HER2-CAR-T) cells and to provide a safety basis for the clinical evaluation of HER2-CAR-T cell therapy. Methods The recombinant lentiviral vector was used to generate HER2-CAR-T cells. Soft agar colony formation assay was used to observe the colony formation of HER2-CAR-T cells, and the colony formation rate was statistically analyzed. The HER2-CAR-T cell suspension was co-incubated with rabbit red blood cell suspension, and the hemolysis of red blood cells was evaluated by direct observation and microplate reader detection. The HER2-CAR-T cell preparation was injected into the ear vein of male New Zealand rabbits, and the stimulating effect of HER2-CAR-T cells on the blood vessels of the animals was observed by staining of tissue sections. The vesicular stomatitis virus envelope glycoprotein (VSV-G) gene of pMD 2.G vector was used as the target sequence, and the safety of the lentiviral vector was verified by real-time fluorescence quantitative PCR. The heart, liver, lung, and kidney of mice receiving HER2-CAR-T cell infusion were collected, and the lesions were observed by HE staining. Results The HER2-CAR-T cells were successfully prepared. These cells did not exhibit soft agar colony formation ability in vitro, and the HER2-CAR-T cell preparation did not cause hemolysis in New Zealand rabbit red blood cells. After the infusion of HER2-CAR-T cells into the ear vein of New Zealand rabbits, no obvious vascular stimulation response was found, and no specific amplification of VSV-G was detected. No obvious lesions were found in the heart, liver, lung and kidney tissues of the treatment group. Conclusion The prepared HER2-CAR-T cells have reliable safety.

A Cancer-Specific Monoclonal Antibody against HER2 Exerts Antitumor Activities in Human Breast Cancer Xenograft Models

Monoclonal antibody (mAb)-based and/or cell-based immunotherapies provide innovative approaches to cancer treatments. However, safety concerns over targeting normal cells expressing reactive antigens still exist. Therefore, the development of cancer-specific mAbs (CasMabs) that recognize cancer-specific antigens with in vivo antitumor efficacy is required to minimize the adverse effects. We previously screened anti-human epidermal growth factor receptor 2 (HER2) mAbs and successfully established a cancer-specific anti-HER2 mAb, H2Mab-250/H2CasMab-2 (IgG1, kappa). In this study, we showed that H2Mab-250 reacted with HER2-positive breast cancer cells but did not show reactivity to normal epithelial cells in flow cytometry. In contrast, a clinically approved anti-HER2 mAb, trastuzumab, recognized both breast cancer and normal epithelial cells. We further compared the affinity, effector activation, and antitumor effect of H2Mab-250 with trastuzumab. The results showed that H2Mab-250 exerted a comparable antitumor effect with trastuzumab in the mouse xenograft models of BT-474 and SK-BR-3, although H2Mab-250 possessed a lower affinity and effector activation than trastuzumab in vitro. H2Mab-250 could contribute to the development of chimeric antigen receptor-T or antibody-drug conjugates without adverse effects for breast cancer therapy.

Reduced Tumor Volume and Increased Necrosis of Human Breast Tumor Xenograft in Mice Pretreated by a Cocktail of Three Specific Anti-HER2 scFvs

PURPOSE

We aimed to assess the effects of a cocktail comprising three specific anti- HER2 scFvs on breast tumor formation in a xenograft mouse model and to evaluate quantitative changes in the tumor using stereological analysis.

METHODS

Three specific anti-HER2 phage antibodies were produced from a scFv-library using phage display technology. The cell binding capacities of the antibodies were assessed via FACS analysis. Soluble forms of the antibodies were prepared by infecting HB2151-E. coli cells and purified using a centrifugal ultrafiltration method. The purification process was evaluated by SDSPAGE analysis. Two forms of scFv cocktails were prepared, soluble scFv and phage-scFv cocktail, which contained an equal amount/phage of each of the three antibodies. Inbred female BALB/c mice were pretreated with 5 and 20 mg/kg of the soluble scFv cocktail and 1011 phage-scFv cocktail/ kg. The mice were then injected with 2×106 SKBR-3 human breast cancer cells. Total tumor, inflammatory and non-inflammatory volumes were estimated using the Cavalieri principle after preparing photomicrograph slides.

RESULTS

The anti-HER2 scFvs showed significantly higher binding to SKBR-3 cells compared to the isotype control. SDS-PAGE analysis confirmed the high purification of the scFvs. Stereological analysis revealed that the group pretreated with 20 mg/kg of the soluble scFv cocktail exhibited the highest reductions in total tumor volume, non-inflammatory volume, and inflammatory volume, with reductions of 73%, 78%, and 72%, respectively, compared to PBS-pretreated mice (P-value < 0.0001). The volumetric ratio of necrotic tissue to total tumor volume increased by 2.2-fold and 2- fold in the 20 mg/kg of soluble scFv cocktail and phage-scFv cocktail groups, respectively, compared to the PBS-treated mice (P-value < 0.05).

CONCLUSION

Pre-treatment with a 20 mg/kg anti-HER2 scFv cocktail resulted in a significant reduction in tumor volume and increased necrotic area in a human breast cancer xenograft model, indicating the remarkable anti-tumor effect of the cocktail in vivo.

Application of quantitative protein mass spectrometric data in the early predictive analysis of membrane-bound target engagement by monoclonal antibodies

Model-informed drug discovery advocates the use of mathematical modeling and simulation for improved efficacy in drug discovery. In the case of monoclonal antibodies (mAbs) against cell membrane antigens, this requires quantitative insight into the target tissue concentration levels. Protein mass spectrometry data are often available but the values are expressed in relative, rather than in molar concentration units that are easier to incorporate into pharmacokinetic models. Here, we present an empirical correlation that converts the parts per million (ppm) concentrations in the PaxDb database to their molar equivalents that are more suitable for pharmacokinetic modeling. We evaluate the insight afforded to target tissue distribution by analyzing the likely tumor-targeting accuracy of mAbs recognizing either epidermal growth factor receptor or its homolog HER2. Surprisingly, the predicted tissue concentrations of both these targets exceed the Kd values of their respective therapeutic mAbs. Physiologically based pharmacokinetic (PBPK) modeling indicates that in these conditions only about 0.05% of the dosed mAb is likely to reach the solid tumor target cells. The rest of the dose is eliminated in healthy tissues via both nonspecific and target-mediated processes. The presented approach allows evaluation of the interplay between the target expression level in different tissues that determines the overall pharmacokinetic properties of the drug and the fraction that reaches the cells of interest. This methodology can help to evaluate the efficacy and safety properties of novel drugs, especially if the off-target cell degradation has cytotoxic outcomes, as in the case of antibody-drug conjugates.

Beyond Neoantigens: Antigens Derived from Tumor Drivers as Cancer Vaccine Targets

A vaccine targeting HER2, a nonmutated but overexpressed tumor antigen, readily primed T cells for ex vivo expansion and adoptive transfer with minimal toxicity. This regimen led to intramolecular epitope spreading in a majority of patients and offers a treatment modality that may improve outcomes for patients with metastatic breast cancer expressing HER2. See related article by Disis et al., p. 3362.

Prognostic and Predictive Value of Immune-Related Gene Expression Signatures vs Tumor-Infiltrating Lymphocytes in Early-Stage ERBB2/HER2-Positive Breast Cancer: A Correlative Analysis of the CALGB 40601 and PAMELA Trials

Importance

Both tumor-infiltrating lymphocytes (TILs) assessment and immune-related gene expression signatures by RNA profiling predict higher pathologic complete response (pCR) and improved event-free survival (EFS) in patients with early-stage ERBB2/HER2-positive breast cancer. However, whether these 2 measures of immune activation provide similar or additive prognostic value is not known.

Objective

To examine the prognostic ability of TILs and immune-related gene expression signatures, alone and in combination, to predict pCR and EFS in patients with early-stage ERBB2/HER2-positive breast cancer treated in 2 clinical trials.

Design, Setting, and Participants

In this prognostic study, a correlative analysis was performed on the Cancer and Leukemia Group B (CALGB) 40601 trial and the PAMELA trial. In the CALGB 40601 trial, 305 patients were randomly assigned to weekly paclitaxel with trastuzumab, lapatinib, or both for 16 weeks. The primary end point was pCR, with a secondary end point of EFS. In the PAMELA trial, 151 patients received neoadjuvant treatment with trastuzumab and lapatinib for 18 weeks. The primary end point was the ability of the HER2-enriched subtype to predict pCR. The studies were conducted from October 2013 to November 2015 (PAMELA) and from December 2008 to February 2012 (CALGB 40601). Data analyses were performed from June 1, 2020, to January 1, 2022.

Main Outcomes and Measures

Immune-related gene expression profiling by RNA sequencing and TILs were assessed on 230 CALGB 40601 trial pretreatment tumors and 138 PAMELA trial pretreatment tumors. The association of these biomarkers with pCR (CALGB 40601 and PAMELA) and EFS (CALGB 40601) was studied by logistic regression and Cox analyses.

Results

The median age of the patients was 50 years (IQR, 42-50 years), and 305 (100%) were women. Of 202 immune signatures tested, 166 (82.2%) were significantly correlated with TILs. In both trials combined, TILs were significantly associated with pCR (odds ratio, 1.01; 95% CI, 1.01-1.02; P = .02). In addition to TILs, 36 immune signatures were significantly associated with higher pCR rates. Seven of these signatures outperformed TILs for predicting pCR, 6 of which were B-cell related. In a multivariable Cox model adjusted for clinicopathologic factors, including PAM50 intrinsic tumor subtype, the immunoglobulin G signature, but not TILs, was independently associated with EFS (immunoglobulin G signature-adjusted hazard ratio, 0.63; 95% CI, 0.42-0.93; P = .02; TIL-adjusted hazard ratio, 1.00; 95% CI, 0.98-1.02; P = .99).

Conclusions and Relevance

Results of this study suggest that multiple B-cell-related signatures were more strongly associated with pCR and EFS than TILs, which largely represent T cells. When both TILs and gene expression are available, the prognostic value of immune-related signatures appears to be superior.

Breast Cancer Vaccines: Disappointing or Promising?

Breast cancer has become the most commonly diagnosed cancer globally. The relapse and metastasis of breast cancer remain a great challenge despite advances in chemotherapy, endocrine therapy, and HER2 targeted therapy in the past decades. Innovative therapeutic strategies are still critically in need. Cancer vaccine is an attractive option as it aims to induce a durable immunologic response to eradicate tumor cells. Different types of breast cancer vaccines have been evaluated in clinical trials, but none has led to significant benefits. Despite the disappointing results at present, new promise from the latest study indicates the possibility of applying vaccines in combination with anti-HER2 monoclonal antibodies or immune checkpoint blockade. This review summarizes the principles and mechanisms underlying breast cancer vaccines, recapitulates the type and administration routes of vaccine, reviews the current results of relevant clinical trials, and addresses the potential reasons for the setbacks and future directions to explore.