HER2-positive Cancer Cells Research Articles

Cellular analyses for label-free and rapid HER2-positive cancer diagnosis based on SPRi-modified with nanobody

Overexpression of human epidermal growth factor receptor-2 (HER2) is an important prognostic indicator for clinical diagnosis, as it results in more invasive cancer cells and lower survival rates. In this study, we developed a novel immunosensor based on surface plasmon resonance imaging (SPRi) modified with nanobody 2 (NB2) to detect the HER2 expression of various cancer cells. Firstly, we established a multi-channel intensity interrogation SPRi system with a refractive index resolution (RIR) of 1 × 10−6 RIU. Then, we fabricated the immunosensor by immobilizing NB2 nanobody on the sensor chip through affinity-based orientation. The NB2 exhibited high specificity for HER2 extracellular domain, enabling specific capture of HER2-positive cancer cells. The results revealed that the sensor could detect the HER2 expression of various living cancer cells by directly injecting cell suspensions. Compared with flow cytometry, SPRi system could obtain similar HER2 expression results with better performance, such as faster response time (<30 min), smaller sample volume (<200 μL), and lower cell concentration (105 cells/mL). The most important of all is that researchers do not need to take complex fluorescent labeling pretreatment of cell samples. Therefore, such immunosensors may offer great potential for rapid personalized treatment planning and enhanced patient outcomes.

Anti-PD-1/Her2 Bispecific Antibody IBI315 Enhances the Treatment Effect of Her2-Positive Gastric Cancer through Gasdermin B-Cleavage Induced Pyroptosis.

The majority of patients with human epidermal growth factor receptor 2 (Her2)-positive gastric cancer develop refractory to Her2-targeted therapy, whereupregulation of immune checkpoints plays an essential role. Herein, a recombinant fully human IgG1 bispecific antibody IBI315 targeting both PD-1 and Her2 is developed and its antitumor efficacy as well as the underlying mechanism is investigated. IBI315 crosslinksthe physical interaction between Her2-positive tumor cells and PD-1-positive T cells, resulting in significantly enhanced antitumor effects compared to each parent antibody or their combination, both in vitro and in vivo mouse tumor models reconstituted with human immune cells using patient-derived xenografts and organoids. Moreover, IBI315 treatment also induces the recruitment and activation of immune cells in tumors. Mechanistically, IBI315 triggers gasdermin B (GSDMB)-mediated pyroptosis in tumor cells, leading to the activation and recruiments of T cells. The activated T cells secret IFNγ, enhancing GSDMB expression and establishing a positive feedback loop of T cell activation and tumor cell killing. Notably, GSDMB is found to be elevated in Her2-positive gastric cancer cells, providing a rationale for IBI315's efficacy. IBI315 is supported here as a promising bispecific antibody-based immunotherapy approach for Her2-positive gastric cancer in preclinical studies, broadening the therapeutic landscape of this patient population.

Coiled-Coil-Based Biofunctionalization of 100 nm Gold Nanoparticles with the Trastuzumab Antibody for the Detection of HER2-Positive Cancer Cells.

We compared different biofunctionalization strategies for immobilizing trastuzumab, an IgG targeting the HER2 biomarker, onto 100 nm spherical gold nanoparticles because of the E/K coiled-coil peptide heterodimer. First, Kcoil peptides were grafted onto the gold surface while their Ecoil partners were genetically encoded at the C-terminus of trastuzumab's Fc region, allowing for a strong and specific interaction between the antibodies and the nanoparticles. Gold nanoparticles with no Kcoil peptides on their surface were also produced to immobilize Ecoil-tagged trastuzumab antibodies via the specific adsorption of their negatively charged Ecoil tags on the positively charged gold surface. Finally, the nonspecific adsorption of wild-type trastuzumab on the gold surface was also assessed, with and without Kcoil peptides grafted on it beforehand. We developed a thorough workflow to systematically compare the immobilization strategies regarding the stability of nanoparticles, antibody coverage, and ability to specifically bind to HER2-positive breast cancer cells. All nanoparticles were highly monodisperse and retained their localized surface plasmon resonance properties after biofunctionalization. A significant increase in the amount of immobilized antibodies was observed with the two oriented coil-based strategies compared to nonspecific adsorption. Finally, all biofunctionalization strategies allowed for the detection of HER2-positive breast cancer cells, but among the investigated approaches, we recommend using the E/K coiled-coil-based strategy for gold nanoparticle biofunctionalization because it allows for the qualitative and quantitative detection of HER2-positive cells with a higher contrast compared to HER2-negative cells.

Synthesis of Novel Dual Target Inhibitors of CDK12 and PARP1 and Their Antitumor Activities in HER2-Positive Breast Cancers.

Several anti-human epidermal growth factor receptor 2 (HER2) treatments have improved the landscape of HER2-positive breast cancer (BC) over the past few years; due to the heterogeneity of the disease itself, the drug resistance mechanisms and relapse are still the main issue in HER2-positive BC. Here, we intended to target simultaneous inhibition of both poly ADP-ribose polymerase 1 (PARP1) and cyclin-dependent kinase 12 (CDK12) that have had an impact on this disease up to their implementation in clinical practice. We successfully screened PARP1 inhibitors (PARPis) containing bicyclic tetrahydropyridine pyrimidines with antitumor activity. Most synthesized compounds with various alcohols were more effective at killing tumor cells than olaparib (ola), especially in HER2-positive cancer cells. Among them, compound 9 showed potent inhibitory effects on PARP1 enzymatic activity and the PAR protein level; moreover, the expression of CDK12 was inhibited by compound 9. Overall, compound 9 exhibited a significant antitumor effect by inhibiting DNA damage repair in tumors.

Radiotherapy combined with pyrotinib plus capecitabine in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer and brain metastases: A single-arm, exploratory trial.

e13024 Background: Previous researches indicated the enhanced radiosensitivity in HER2-positive cancer cells by pyrotinib. For patients with treatment-naive brain metastases and central nervous system (CNS) symptoms, whether radiotherapy (current mainstay treatment) combined with pyrotinib-based systemic regimen is more beneficial remains unclear. This study explored radiotherapy combined with pyrotinib plus capecitabine in this population. Methods: In this exploratory trial (NCT04767828), patients aged 18-75 years who had HER2-positive metastatic breast cancer and untreated symptomatic brain metastases with an Eastern Cooperative Oncology Group performance status of 0-2 were included. Patients with meningeal metastases or without measurable CNS lesions were excluded. Eligible patients received whole-brain radiotherapy (WBRT) or stereotactic radiotherapy (SRT). The irradiation sites, total radiation dose, and fractions were decided by investigator based on the number of CNS lesions and size. Pyrotinib (400 mg, once a day) and capecitabine (1000 mg/m2, twice a day, on days 1-14 of each 21-day cycle) were given since the start of radiotherapy until disease progression or intolerable toxicity. The primary endpoint was CNS progression-free survival (PFS), assessed by Response Assessment in Neuro-Oncology Brain Metastases (RANO-BM). Extracranial lesions were assessed by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Results: Between May 5, 2020 and November 25, 2022, a total of 19 patients were enrolled. Thirteen (68%) patients had other visceral metastases, and 18 (95%) had prior trastuzumab treatment (5 for early breast cancer, 12 for advanced breast cancer, and 1 for both). Fifteen (79%) patients received WBRT and 4 (21%) received SRT. By the data cutoff date on January 16, 2023, the median follow-up duration was 15.0 months (range, 1.7-24.8). Median CNS PFS was 10.0 months (95% CI, 5.3-14.7). CNS objective response rate was 100%, including two (11%) patients with CNS complete response. Median overall PFS was 8.5 months (95% CI, 4.8-12.2). Median overall survival was 19.0 months (95% CI, 13.1-24.9). The most common grade 3 or 4 adverse events were vomiting (16%) and nausea (11%). For 11 patients with available results of Mini-Mental State Examination (MMSE), 10 (91%) had normal cognitive function during study period or recovered to normal level within 6 months after radiotherapy. Conclusions: Radiotherapy combined with pyrotinib plus capecitabine shows favorable CNS response and promising survival outcomes in patients with HER2-positive metastatic breast cancer and untreated symptomatic brain metastases, with an acceptable safety profile. This combination strategy warrants further validation in large samples. Clinical trial information: NCT04767828 .

Lyophilized liposomal formulation of a peptidomimetic-Dox conjugate for HER2 positive breast and lung cancer

Nanocarrier-mediated administration of chemotherapeutic drugs can increase the therapeutic index of drugs by reducing off-target site toxicity. Ligand-targeted drug delivery can be utilized to deliver chemotherapeutic drugs to cancer cells selectively and specifically. Here we report the evaluation of a lyophilized formulation of a liposome containing a peptidomimetic-doxorubicin conjugate for targeted delivery of doxorubicin to HER2-positive cancer cells. The lyophilized liposomal formulation exhibited improved release of peptidomimetic-doxorubicin conjugate at pH 6.5 compared to 7.4 and improved cellular uptake in cancer cells at pH 6.5. In vivo studies indicated that pH-sensitive formulation exhibited site-specific formulation delivery and improved anticancer efficacy than free doxorubicin. The findings suggested that combining a lyophilized pH-sensitive liposomal formulation containing trehalose as lyoprotectant with a targeting ligand coupled cytotoxic agent is a potential method for cancer chemotherapy while maintaining long-term stability at 4 °C of the liposome formulation.

Abstract 1803: GNP101, anti-HER2-IFN-β mutein immunocytokine, for the treatment of Trastuzumab deruxtecan-resistant HER2-positive cancers

Abstract Background: Trastuzumab deruxtecan (T-DXd) has been approved in various types cancer and recently expanded its indication to cancers with various HER2 expressions, such as HER2-low breast cancer. Since the effect of T-DXd is based on toxin payload, topoisomerase I inhibitor, the emergence of toxin-resistant cancer cells is unavoidable. Clinical cases of Primary, or secondary resistance to T-DXd have been reported. Therefore, it is necessary to develop novel drugs that can effectively exhibit antitumor effects against T-DXd-resistant carcinoma. Interferon beta (IFN-β), a promising potent cytokine, has been attracting attention for treatment of cancer. It is one of the few cytokines that induce tumor cell killing directly. Importantly, it could be an alternative to conventional drug-resistant cancer, because it regulates tumor growth in a way different from cytotoxic agents. Here, GNP101, an IFN-β mutein-based immunocytokine, exhibits antitumor properties against HER2-positive cancers, including T-DXd-resistant cancer. Method: A panel of human HER2-positive cancer cell lines derived from breast, stomach and lung were treated with GNP101 or HER2 therapeutics (trastuzumab, T-DM1, T-DXd) to compare direct antitumor effects. To generate a T-DXd-resistant cells, HCC1954, NCI-N87 and Calu-3 were exposed to the IC50, IC80 or IC90 of T-DXd by cyclic treatment. After 4 months, HCC1954-R cells were established and IFN-β signaling was assessed by STAT1-phosphorylation. The direct antitumor effect of GNP101 in vivo was tested in HER2-positive cancer xenograft models. Result: GNP101 showed superior potency compared to existing HER2 therapies (trastuzumab, T-DM1, and T-DXd) in all HER2-positive cancers regardless of tissue origin. To investigate the antitumor effect of GNP101 against T-DXd resistant cancer, we first generated T-DXd-resistant cell line (HCC1954-R). These HCC1954-R cells were strongly resistant to T-DXd, and showed no antitumor effect even at 100 nM of T-DXd. However, they were sensitive to GNP101, suggesting that GNP101 maintained its antitumor effect in T-DXd resistant cells. In addition, there was no difference in IFN-β-induced STAT1 phosphorylation between the parent cell and HCC1954-R. Taken together, these results indicate that HCC1954-R cells maintain IFN-β signaling and are selectively resistant to T-DXd. The activities of GNP101, T-DM1 and T-DXd on HER2-positive cancer cells were compared in vivo. GNP101 inhibited the growth of tumor by 90%, with no difference from that of T-DXd or T-DM1. Conclusion: We have evaluated the antitumor properties of GNP101, a trastuzumab-IFN-β mutein in HER2-expressing cancer. Given that GNP101 retains its antitumor properties in T-DXd-resistant cancer cells, the study suggests that anti-HER2-IFN-β mutein is a promising candidate for the treatment of HER2-positive and T-DXd resistant cancers. Citation Format: Chan Gyu Lee, Minkyung Park, Hyun Kyung Lee, Na Young Kim, Jun Young Choi, Sungyoul Hong, Young Kee Shin, Hae Min Jeong. GNP101, anti-HER2-IFN-β mutein immunocytokine, for the treatment of Trastuzumab deruxtecan-resistant HER2-positive cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1803.

Abstract 2633: Zanidatamab zovodotin (ZW49) induces hallmarks of immunogenic cell death and is active in patient-derived xenograft models of gastric cancer

Abstract Zanidatamab zovodotin (ZW49) is an antibody drug conjugate (ADC) comprised of a bispecific anti-HER2 IgG1 antibody (ZW25, zanidatamab) conjugated to a microtubule inhibitor auristatin payload (ZD02044) via a protease cleavable linker. Clinical studies of ZW49 in HER2-expressing advanced solid tumors are currently underway (NCT03821233). We have previously presented data illustrating the rapid internalization of ZW49 and the anti-tumor activity of ZW49 in multiple patient-derived xenograft models originating from breast carcinomas. Here we present ZW49’s ability to induce in vitro hallmarks of immunogenic cell death (ICD) including increased calreticulin exposure, increased high mobility group box-1 (HMGB1) exposure, and increased extracellular ATP secretion in a HER2 dependent manner. Additionally, we present the results from a study evaluating the anti-tumor activity of ZW49 in a panel of patient-derived xenografts of gastric cancer. HER2-positive SK-BR-3 and HER2-negative MDA-MB-468 tumor cell lines were treated with ZW49 and cell surface calreticulin was assessed by flow cytometry. ZW49 treatment of SKBR-3 cells induced a significantly higher percentage of cells staining positive for cell surface calreticulin compared to untreated cells. In contrast, ZW49 treatment of MDA-MB-468 cells resulted in no significant difference in the percentage of cells staining positive for calreticulin compared to untreated cells. ZW49 treated HER2-positive cancer cell lines SK-BR-3 and SK-OV-3 induced higher levels of extracellular ATP compared to untreated cells. In the HER2-negative cell line MDA-MB-468, treatment with ZW49 did not alter levels of extracellular ATP compared to untreated cells. ZW49 induced higher levels of HMGB1 in the HER2-positive cancer cell lines SKBR3 and N87 compared to untreated cells, whereas in the HER2-negative cell line MDA-MB-468, ZW49 induced similar levels of HMGB1 to untreated cells. Anti-tumor activity was observed in 5/7 (71%) PDX models of gastric cancer after a single i.v. dose of 6 mg/kg, including in models with moderate and weak HER2 expression. The strong anti-tumor activity of ZW-49 in vivo, together with its ability to induce ICD and potential adaptive immune responses, support ZW49 as a promising ADC for the treatment of HER2-expressing cancers warranting further investigation, including potential combination with checkpoint inhibitors. Citation Format: Stuart D. Barnscher, Andrea Hernández Rojas, Kevin J. Hamblett, Nichole Escalante. Zanidatamab zovodotin (ZW49) induces hallmarks of immunogenic cell death and is active in patient-derived xenograft models of gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2633.

Modular Synthesis of Semiconducting Graft Copolymers to Achieve "Clickable" Fluorescent Nanoparticles with Long Circulation and Specific Cancer Targeting.

Semiconducting polymer nanoparticles (SPNs) are explored for applications in cancer theranostics because of their high absorption coefficients, photostability, and biocompatibility. However, SPNs are susceptible to aggregation and protein fouling in physiological conditions, which can be detrimental for in vivo applications. Here, a method for achieving colloidally stable and low-fouling SPNs is described by grafting poly(ethylene glycol) (PEG) onto the backbone of the fluorescent semiconducting polymer, poly(9,9'-dioctylfluorene-5-fluoro-2,1,3-benzothiadiazole), in a simple one-step substitution reaction, postpolymerization. Further, by utilizing azide-functionalized PEG, anti-human epidermal growth factor receptor 2 (HER2)antibodies, antibody fragments, or affibodies are site-specifically "clicked" onto the SPN surface, which allows the functionalized SPNs to specifically target HER2-positive cancer cells. In vivo, the PEGylated SPNs are found to have excellent circulation efficiencies in zebrafish embryos for up to seven days postinjection. SPNs functionalized with affibodies are then shown to be able to target HER2 expressing cancer cells in a zebrafish xenograft model. The covalent PEGylated SPN system described herein shows great potential for cancer theranostics.

Molecular imprinting of miR-559 on a peptide-immobilized poly L-DOPA/silica core-shell and in vitro investigating its effects on HER2-positive breast cancer cells.

In a significant percentage of breast cancers, increased expression of the HER2 receptor is seen and is associated with the spread and worsening of the disease. This research aims to investigate the effect of miR-559 (which targets HER2 mRNA) on SKBR3 breast cancer cells and the possibility of their effective delivery with polymeric nanoparticles and tumor-targeting peptides. L-DOPA monomers were polymerized on the surface of silica nanoparticles in the presence of miR-559 (as a molecular template for molecular imprinting) then an anti-HER2 peptide coupled to the surface of these polymeric nanocomposites (miR-NC-NL2), and the effects of this construct against a HER2-positive breast cancer cells (SKBR3 cells) investigated in vitro conditions. The results showed that miR-NC-NL2 is selective for HER2-positive cells and delivers the miR-559 to them in a targeted manner. miR-NC-NL2 decreased the proliferation of SKBR3 cells and reduced the expression and production of HER2 protein in these cells. Effective and targeted delivery of miR-559 to HER2-positive cancer cells by the miR-NC-NL2 promises the therapeutic potential of this nascent structure based on its inhibitory effect on cancer growth and progression. Of course, animal experiments require a better understanding of this structure's anti-tumor effects.

Baicalein suppresses HER2-mediated malignant transformation of HER2-overexpressing ovarian cancer cells by downregulating HER2 gene expression.

The upregulation of the HER2 oncogene is associated with a variety of human cancers and is associated with poor prognosis. Baicalein is reported to have anti-tumor activity, but the molecular mechanism of this effect in HER2-positive cancer cells has not been studied. In this study, our data showed that baicalein can inhibit the proliferation and transformation potential of ovarian cancer cells overexpressing HER2. Baicalein treatment caused a dose-dependent inhibition of HER2 gene expression at the transcriptional level. Baicalein acted on ovarian cancer cells overexpressing HER2 to downregulate the PI3K/Akt signaling pathway downstream of HER2 and inhibit the expression or activity of downstream targets, such as VEGF and cyclin D1 and MMP2. Oral administration of baicalein supplemented with a pharmaceutical excipient significantly inhibited the growth of HER2-overexpressing ovarian SKOV-3 cancer xenografts in mice. These results suggest that downregulation of HER2 gene expression by baicalein at the transcriptional level contributes to inhibit the in vitro and in vivo proliferation and HER2-mediated malignant transformation of HER2-overexpressing ovarian cancer cells.

Synergistic Combinatorial effect of L-asparaginase and Trastuzumab against HER2+ breast cancer cells

Multi-targeted drug combinations which selectively inhibit the proliferation of cancer cells are required for effective anticancer treatment. The current anti-HER2 positive breast cancer therapy involves Trastuzumab and doxorubicin drug combination which produces toxic side effects in clinical settings including high cardiotoxicity. In this study, anticancer activity of single drug as well as the drug combination effect of L-asparaginase (Celginase) and Trastuzumab (Herceptin) was studied on HER2 positive breast cancer (SKBR3) cells. Inhibition of cell proliferation assay based on fluorescence readout was studied to estimate the anticancer effect of the drugs. HUVEC cells were used as negative control cells. Individually as a single drug, Trastuzumab (Herceptin) and L-asparaginase (Celginase) showed anticancer activity against SKBR3 cells with IC50 value of 0.031ng/ml and 1.168µg/ml respectively. The drug combination interaction of Trastuzumab and L-asparaginase resulted in combination index of less than 1(CI &lt; 1) showing their synergistic effect against SKBR3 cells. No cytotoxic effect was observed in control HUVEC cells. The results suggested that the antitumor activity of Trastuzumab and L-asparaginase against HER2 positive breast cancer was found specific to HER2 positive cancer (SKBR3) cells. This synergistic drug interaction of L-asparaginase and Trastuzumab could be further explored to as an alternative to current drug combination therapy against the HER2 positive breast cancer.

Fluorescent Magnetic Nanoparticles for Bioimaging through Biomimetic Surface Modification

Nanostructured materials and systems find various applications in biomedical fields. Hybrid organo-inorganic nanomaterials are intensively studied in a wide range of areas, from visualization to drug delivery or tissue engineering. One of the recent trends in material science is biomimetic approaches toward the synthesis or modification of functional nanosystems. Here, we describe an approach toward multifunctional nanomaterials through the biomimetic polymerization of dopamine derivatives. Magnetite nanoparticles were modified with a combination of dopamine conjugates to give multifunctional magneto-fluorescent nanocomposites in one synthetic step. The obtained material showed excellent biocompatibility at concentrations up to 200 μg/mL and an in vivo biodistribution profile typical for nanosized formulations. The synthesized systems were conjugated with antibodies against HER2 to improve their selectivity toward HER2-positive cancer cells. The produced material can be used for dual magneto-optical in vivo studies or targeted drug delivery. The applied synthetic strategy can be used for the creation of various multifunctional hybrid nanomaterials in mild conditions.

Pan-HER Tyrosine Kinase Inhibitor Pyrotinib Enhances Radiosensitivity via ERK1/2 Pathway in HER2-Positive Gastric Cancer

Background: Radiotherapy has an unsatisfactory effect on gastric cancer. The purpose of this study was to investigate the effect of pyrotinib, a highly effective human epidermal growth factor receptor (HER) family inhibitor, on the radiosensitivity of HER2-positive gastric cancer and its mechanism in vivo and in vitro. Methods: NCI-N87 and SNU-216 were HER2-positive gastric cancer cell lines; these cell lines were treated with or without 0.01 μM pyrotinib 12 h before irradiation. The proliferation capacity was determined by CCK8, and clone formation experiments were used to test the radiosensitization effect of pyrotinib. The expression of HER2, γ-H2AX, apoptosis protein, senescence-associated proteins, and AKT/ERK signaling pathway changes were determined by Western blot. Cell cycle and apoptosis were established by flow cytology. Immunofluorescence was utilized to detect the expression of HER2 and γ-H2AX. Senescence cells were stained by β-galactosidase staining method. Pathway enrichment analysis was tested by RNA sequencing. Next, a xenograft tumor model was constructed in nude mice for verification in vivo. Results: The clone formation experiment indicated the radiosensitivity of pyrotinib. The combined treatment can inhibit the entry of HER2 protein into the nucleus and reduce the phosphorylation of the ERK signaling pathway caused by irradiation. Pyrotinib also enhances DNA damage; induces apoptosis, G2/M phase arrest; and promotes senescence. In the xenograft model, the tumor inhibition rate was significantly stronger in the combined treatment group. Conclusions: Our results demonstrated that pyrotinib can induce radiosensitivity in HER2-positive gastric cancer in vivo and in vitro. This effect is through reducing irradiation-induced HER2 entry into the nucleus and inhibiting ERK1/2 signaling pathway.

Complementation Dependent Enzyme Prodrug Therapy Enables Targeted Activation of Prodrug on HER2-Positive Cancer Cells.

Antibodies have been explored for decades for the delivery of small molecule cytotoxins directly to diseased cells. In antibody-directed enzyme prodrug therapy (ADEPT), antibodies are armed with enzymes that activate nontoxic prodrugs at tumor sites. However, this strategy failed clinically due to off-target toxicity associated with the enzyme prematurely activating prodrug systemically. We describe here the design of an antibody-fragment split enzyme platform that regains activity after binding to HER2, allowing for site-specific activation of a small molecule prodrug. We evaluated a library of fusion constructs for efficient targeting and complementation to identify the most promising split enzyme pair. The optimal pair was screened for substrate specificity among chromogenic, fluorogenic, and prodrug substrates. Evaluation of this system on HER2-positive cells revealed 7-fold higher toxicity of the activated prodrug over prodrug treatment alone. Demonstrating the potential of this strategy against a known clinical target provides the basis for a unique therapeutic platform in oncology.

The production of the first functional antibody mimetic in higher plants: the chloroplast makes the DARPin G3 for HER2 imaging in oncology

BackgroundDesigned mimetic molecules are attractive tools in biopharmaceuticals and synthetic biology. They require mass and functional production for the assessment of upcoming challenges in the near future. The DARPin family is considered a mimetic pharmaceutical peptide group with high affinity binding to specific targets. DARPin G3 is designed to bind to the HER2 (human epidermal growth factor receptor 2) tyrosine kinase receptor. Overexpression of HER2 is common in some cancers, including breast cancer, and can be used as a prognostic and predictive tool for cancer. The chloroplasts are cost-effective alternatives, equal to, and sometimes better than, bacterial, yeast, or mammalian expression systems. This research examined the possibility of the production of the first antibody mimetic, DARPin G3, in tobacco chloroplasts for HER2 imaging in oncology.ResultsThe chloroplast specific DARPin G3 expression cassette was constructed and transformed into N. tabacum chloroplasts. PCR and Southern blot analysis confirmed integration of transgenes as well as chloroplastic and cellular homoplasmy. The Western blot analysis and ELISA confirmed the production of DARPin G3 at the commercial scale and high dose with the rate of 20.2% in leaf TSP and 33.7% in chloroplast TSP. The functional analysis by ELISA confirmed the binding of IMAC purified chloroplast-made DARPin G3 to the extracellular domain of the HER2 receptor with highly effective picomolar affinities. The carcinoma cellular studies by flow cytometry and immunofluorescence microscopy confirmed the correct functioning by the specific binding of the chloroplast-made DARPin G3 to the HER2 receptor on the surface of HER2-positive cancer cell lines.ConclusionThe efficient functional bioactive production of DARPin G3 in chloroplasts led us to introduce plant chloroplasts as the site of efficient production of the first antibody mimetic molecules. This report, as the first case of the cost-effective production of mimetic molecules, enables researchers in pharmaceuticals, synthetic biology, and bio-molecular engineering to develop tool boxes by producing new molecular substitutes for diverse purposes.

Site-Selective Lysine Acetylation of Human Immunoglobulin G for Immunoliposomes and Bispecific Antibody Complexes.

Site-selective acetylation of a single lysine residue in a protein that reaches a lysine acetyltransferase's accuracy, precision, and reliability is challenging. Here, we report a peptide-guided, proximity-driven group transfer reaction that acetylates a single lysine residue, Lys 248, of the fragment crystallizable region (Fc region) in the heavy chain of the human Immunoglobulin G (IgG). An Fc-interacting peptide bound with the Fc domain and positioned a phenolic ester close to Lys 248, which induced a nucleophilic reaction and resulted in the transfer of an acetyl group to Lys 248. The acetylation reaction proceeded to a decent yield under the physiological condition without the need for deglycosylation, unnatural amino acids, or catalysts. Along with acetylation, functional moieties such as azide, alkyne, fluorescent molecules, or biotin could also be site-selectively installed on Lys 248, allowing IgG's further derivatization. We then synthesized an antibody-lipid conjugate and constructed antibody-conjugated liposomes (immunoliposomes), targeting HER2-positive (HER2+) cancer cells. We also built a bispecific antibody complex (bsAbC) covalently linking an anti-HER2 antibody and an anti-CD3 antibody. The bsAbC showed in vitro effector-cell-mediated cytotoxicity at nanomolar concentrations. Compared with bispecific antibodies (bsAbs), bsAbCs are constructed based on native IgGs and contain two antigen-binding sites to each antigen, twice that of bsAbs. Altogether, this work reports a method of site-selective acetylation of native antibodies, highlights a facile way of site-selective IgG functionalization, and underscores the potential of bsAbCs in cancer immunotherapy.

Design, Synthesis, and Bioevaluation of a Novel Hybrid Molecular Pyrrolobenzodiazepine-Anthracenecarboxyimide as a Payload for Antibody-Drug Conjugate.

A novel series of hybrid molecules combining pyrrolobenzodiazepine (PBD) and anthracenecarboxyimide pharmacophores were designed, synthesized, and tested for in vitro cytotoxicity against various cancer cell lines. The most potent compound from this series, 37b3, exhibited a subnanomolar level of cytotoxicity with an IC50 of 0.17-0.94 nM. 37b3 induced DNA damage and led to tumor cell cycle arrest and apoptosis. We employed 37b3 as a payload to conjugate with trastuzumab to obtain the antibody-drug conjugate (ADC) T-PBA. T-PBA maintained its mode of target and internalization ability of trastuzumab. We demonstrated that T-PBA could be degraded through the lysosomal pathway to release the payload 37b3 after internalization. T-PBA showed a powerful killing effect on Her2-positive cancer cells in vitro. Furthermore, T-PBA significantly inhibited tumor growth in gastric and ovarian cancer xenograft mouse models without overt toxicity. Collectively, these studies suggest that T-PBA represents a promising new ADC that deserves further investigation.

Multifunctional Nanoparticles Based on Iron Oxide and Gold-198 Designed for Magnetic Hyperthermia and Radionuclide Therapy as a Potential Tool for Combined HER2-Positive Cancer Treatment.

Iron oxide nanoparticles are commonly used in many medical applications as they can be easily modified, have a high surface-to-volume ratio, and are biocompatible and biodegradable. This study was performed to synthesize nanoparticles designed for multimodal HER2-positive cancer treatment involving radionuclide therapy and magnetic hyperthermia. The magnetic core (Fe3O4) was coated with a gold-198 layer creating so-called core-shell nanoparticles. These were then further modified with a bifunctional PEG linker and monoclonal antibody to achieve the targeted therapy. Monoclonal antibody—trastuzumab was used to target specific breast and nipple HER2-positive cancer cells. The nanoparticles measured by transmission electron microscopy were as small as 9 nm. The bioconjugation of trastuzumab was confirmed by two separate methods: thermogravimetric analysis and iodine-131 labeling. Synthesized nanoparticles showed that they are good heat mediators in an alternating magnetic field and exhibit great specific binding and internalization capabilities towards the SKOV-3 (HER2 positive) cancer cell line. Radioactive nanoparticles also exhibit capabilities regarding spheroid degradation without and with the application of magnetic hyperthermia with a greater impact in the case of the latter. Designed radiobioconjugate shows great promise and has great potential for in vivo studies regarding magnetic hyperthermia and radionuclide combined therapy.

Abstract 5334: Targeting the hippo transducer YAP overcomes trastuzumab-resistance in HER2-positive cancers

Abstract Background: Human epithelial growth factor receptor 2 (HER2) is a well-established therapeutic target in HER2-positive breast and gastric cancer. Recently, novel HER2-targeting agents are being developed after trastuzumab, and HER2-targeted therapies have been attempted in across solid tumor types, including biliary tract cancer. In these aspects, it is essential to understand and elucidate the resistant mechanism of the HER2-targeting strategies. Yes-associated protein (YAP), a transcription factor of the Hippo pathway, function as proto-oncoproteins by inducing target genes involved in cancer cell survival and proliferation (Zhao B, et al. Genes Develop 2008). Also, YAP is emerging as a resistance mechanism of cytotoxic and targeted drugs. In this study, we explore the role of YAP in overcoming resistance to trastuzumab in HER2-positive cancer cells. Methods: Four trastuzumab-resistant (HR) cell lines were established using HER2-postive gastric and biliary tract cancer cell lines (N87, SNU216, SNU2670, and SNU2773) (Jin MH, et al. Mol Cancer Ther. 2017). YAP siRNA and Verteporfin (YAP-TEAD inhibitor) were used to downregulate YAP. MTT assay, cell cycle analysis, western blot and migration assay were performed to analyze the antitumor effects through YAP downregulation. In order to elucidate tumor cell immune-modulation by YAP, human PBMC co-culture was used and immune markers, such as programmed death-ligand 1 (PD-L1), were analyzed in HR cell lines. Results: Increase of receptor tyrosine kinase-like orphan receptor 1/2 (ROR1/2) expression was observed in the HR cells. Relatively high expression of pYAP, YAP, and transcriptional co-activator with PDZ-binding motif (TAZ) were observed in the HR cells (SNU216HR, SNU2670HR and SNU2773HR) compared to parental cells. Reducing overexpressed YAP in HR cells resulted in tumor cell growth inhibition. In cell cycle analysis, the increase of subG1 phase through YAP downregulation was observed, and cyclinD, B, A and BCL-XL were effectively decreased. Migration was also inhibited by the decrease in YAP expression. By verteporfin treatment, changes in immune markers including increase of CD80 and decrease of PD-L1 was found. In addition, p-STAT3 and IL6, Which regulate PD-L1, were also decreased through the reduction of YAP. In HR cells treated with siYAP, there was a tendency to increase CD8+ T cells upon PBMC co-culture. Conclusion: YAP is upregulated in trastuzumab-resistant (HR) cells and upregulated YAP induce PD-L1 expression. Inhibition of YAP shows anti-tumor effects and modulates immune status. Collectively, our results suggest that inhibition of YAP is one of promising strategies to overcome trastuzumab resistance in HER2-positive cancers. Citation Format: Ah Rong Nam, Jeesun Yoon, Kyoung-Seok Oh, Jae-Min Kim, Ju-Hee Bang, Tae-Yong Kim, Do-Youn Oh. Targeting the hippo transducer YAP overcomes trastuzumab-resistance in HER2-positive cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5334.