In vivo activity of novel anti-ErbB2 antibody chA21 alone and with Paclitaxel or Trastuzumab in breast and ovarian cancer xenograft models

Potent synergistic anti-tumor activity of a novel humanized anti-HER2 antibody hersintuzumab in combination with trastuzumab in xenograft models

Immunotherapy of HER2-overexpressing cancers by FDA approved monoclonal antibodies (mAbs) such as trastuzumab and pertuzumab has shown promising results. We have recently produced a novel humanized anti-HER2 mAb, hersintuzumab, which did not sterically inhibit binding of trastuzumab and pertuzumab to HER2, thus recognizing a distinct epitope on subdomain I + II of HER2. In this study, we assessed the in vitro and in vivo anti-tumor activity of this mAb individually and in combination with trastuzumab. Different HER2-overexpressing human cancer cell lines, including SKOV3, NCI-N87 HCC1954 and BT-474 were cultured and binding reactivity of Hersintuzumab to these cell lines was analyzed by flow cytometry. In addition, the inhibitory effect of different concentrations of hersintuzumab, trastuzumab and their combination on tumor cells growth was assessed by XTT assay. For Assessment of tumor growth inhibition in xenograft model, Balb/c athymic nude mice were subcutaneously injected with NCI-N87 and SKOV3 tumor cells and then treated intravenously with these mAbs. Our results showed that hersintuzumab could bind to all HER2-overexpressing cell lines similar to trastuzumab. In vitro experiments showed that both hersintuzumab and trastuzumab individually and in combination inhibited growth of all cell lines with the exception of HCC-1954.Inhibitory effect of the combination of mAbs was significantly higher than that of each mAb alone. Similar results were obtained in the gastric (NCI-N87) and ovarian (SKOV-3) tumor xenograft models. Hersintuzumab in combination with trastuzumab induces synergic anti-tumor effects on HER2-overexpressing cells in vitro and in vivo and is potentially a therapeutic tool for treatment of HER2-overexpressing cancers.

[89Zr]-Pertuzumab PET Imaging Reveals Paclitaxel Treatment Efficacy Is Positively Correlated with HER2 Expression in Human Breast Cancer Xenograft Mouse Models

Paclitaxel (PTX) treatment efficacy varies in breast cancer, yet the underlying mechanism for variable response remains unclear. This study evaluates whether human epidermal growth factor receptor 2 (HER2) expression level utilizing advanced molecular positron emission tomography (PET) imaging is correlated with PTX treatment efficacy in preclinical mouse models of HER2+ breast cancer. HER2 positive (BT474, MDA-MB-361), or HER2 negative (MDA-MB-231) breast cancer cells were subcutaneously injected into athymic nude mice and PTX (15 mg/kg) was administrated. In vivo HER2 expression was quantified through [89Zr]-pertuzumab PET/CT imaging. PTX treatment response was quantified by [18F]-fluorodeoxyglucose ([18F]-FDG) PET/CT imaging. Spearman's correlation, Kendall's tau, Kolmogorov-Smirnov test, and ANOVA were used for statistical analysis. [89Zr]-pertuzumab mean standard uptake values (SUVmean) of BT474 tumors were 4.9 ± 1.5, MDA-MB-361 tumors were 1.4 ± 0.2, and MDA-MB-231 (HER2-) tumors were 1.1 ± 0.4. [18F]-FDG SUVmean changes were negatively correlated with [89Zr]-pertuzumab SUVmean (r = -0.5887, p = 0.0030). The baseline [18F]-FDG SUVmean was negatively correlated with initial [89Zr]-pertuzumab SUVmean (r = -0.6852, p = 0.0002). This study shows PTX treatment efficacy is positively correlated with HER2 expression level in human breast cancer mouse models. Molecular imaging provides a non-invasive approach to quantify biological interactions, which will help in identifying chemotherapy responders and potentially enhance clinical decision-making.

Anti-HER2/neu Antibody Reduces Chemotherapy-Induced Ovarian Toxicity-From Bench to Bedside

Background: Trastuzumab, a humanized anti-human epidermal growth factor receptor 2 (HER2/neu) antibody, is considered a standard treatment in addition to chemotherapy in the adjuvant setting for HER2/neu-positive breast cancer, yet its impact on fertility and ovarian reserve remains obscure. We aimed to study the effect of anti-HER2/neu on chemotherapy-induced ovarian toxicity in both clinical and preclinical settings. Methods: We prospectively enrolled breast cancer patients below the age of 42 years who were treated with chemotherapy with or without trastuzumab into the study. Anti-Müllerian hormone (AMH) was measured 6 and 12 months post-chemotherapy as an ovarian reserve indicator. In the animal model, pubertal mice were injected with cyclophosphamide or paclitaxel with or without anti-HER2/neu, or saline, and sacrificed 1 week or 3 months later. Ovarian apoptosis, proliferation and vascularity were measured by immunohistochemistry and ovarian reserve was measured by morphometric analysis and serum-AMH. Results: Thirty-three patients with early breast cancer were enrolled into the study. Nineteen patients had HER2/neu negative cancer and were treated with chemotherapy and 14 had HER2/neu positive cancer and were treated with chemotherapy and trastuzumab. In all patients, AMH levels declined to undetectable values immediately post-treatment, but regained for 57.1% of the HER2/neu positive cohort and 36.8% of the negative cohort (p < 0.05). In the preclinical setting, anti-HER2/neu antibody, in combination with chemotherapy, displayed lessened ovarian and vascular damage. Conclusions: Our results indicate that trastuzumab may alleviate chemotherapy-induced ovarian toxicity that may be mediated via its effect on ovarian vasculature.

The Wnt3a/β-catenin/TCF7L2 signaling axis reduces the sensitivity of HER2-positive epithelial ovarian cancer to trastuzumab

Epithelial ovarian cancer (EOC) is one of the most common and lethal gynecological cancers. Novel therapeutic agents have been developed for EOC, but patient survival remains poor. Trastuzumab has been approved for breast and gastric cancers with high expression of human epidermal growth factor receptor 2 (HER2), but it has not achieved any clinical success in EOC. Dysregulated Wnt/β-catenin signaling is involved in cancer development, but whether it plays a role in EOC resistance to trastuzumab remains largely unknown. Here, we observed that high expression of Wnt3a, β-catenin and TCF7L2, which can form a signaling axis in the Wnt/β-catenin pathway, commonly existed in HER2-positive EOC tissue samples and was correlated with a poor patient prognosis. Cell proliferation and migration assays and nude mouse xenograft model experiments demonstrated that the Wnt3a/β-catenin/TCF7L2 signaling axis promoted tumor cell growth and metastasis and reduced tumor sensitivity to trastuzumab. Analysis of downstream Akt signaling suggested that the function of the Wnt3a/β-catenin/TCF7L2 signaling axis was mediated, at least in part, through increasing Akt phosphorylation. Overall, this study reveals a crucial role for the Wnt3a/β-catenin/TCF7L2 signaling axis in EOC resistance to trastuzumab and the potential application of HER2-targeted drugs combined with inhibitors of this signaling axis for EOC treatment.

Differential Effects of Inhibitory and Stimulatory Anti-HER2 Monoclonal Antibodies on AKT/ERK Signaling Pathways

Objective:

Homo- and heterodimerization of the receptor tyrosine kinase HER2 hyperactivate several downstream signaling pathways, leading to uncontrolled growth and proliferation of tumor cells. Anti-HER2 monoclonal antibodies (mAbs) may induce different effects on HER2 dimerization and signaling.

Methods:

The effect of two inhibitory (2A8, 1T0) and one stimulatory (1H9) anti-HER2 mAbs either alone or in combination with trastuzumab was investigated on AKT and ERK signaling pathways and HER2 degradation in a human breast cancer cell line (BT-474) by Western blotting.

Result:

While 1H9 mAb had no significant effect on AKT and ERK signaling pathways, 1T0 and 2A8 mAbs inhibited phosphorylation of both pathways. Combination of 1T0 mAb with trastuzumab resulted in significant synergistic inhibition of both pathways and HER2 degradation, much more potently than the combination of trastuzumab and pertuzumab.

Conclusion:

Our data indicate that anti-HER2 mAbs may induce different signaling pathways depending on their effect on tumor cell growth and proliferation. The significant inhibition of ERK and AKT phosphorylation by 1T0 alone or particularly in combination with trastuzumab suggests its potential therapeutic application for targeted immunotherapy of HER2 overexpressing malignancies.

Selection, purification, and characterization of a HER2-targeting soluble designed ankyrin repeat protein by E. coli surface display using HER2-positive melanoma cells

Human epidermal growth factor receptor 2 (HER2) is a powerful target for cancer immune therapy. The development of anti-HER2 monoclonal antibodies targeting different domains of HER2 is quite effective. However, the selection and production of multivalent antibodies are complicated. In this study, a mimivirus-based designed ankyrin repeat protein (DARPin) targeting HER2 was selected from an artificial library by bacteria surface display. The selection was performed on HER2-positive B16BL6/E2 melanoma cells and HER2-nagative cells. DARPin selected from the library could be expressed in soluble form with a yield of 70 mg/L. After purified by two continuous and easy steps, the purity of DARPin was 90% as established by SDS-PAGE and RP-HPLC. Selected DARPin showed significant HER2-targeting ability with an affinity of 1.05 ± 0.47 µM. MTT assay demonstrated that at the concentration of 640 nM, the selected DARPin dimer could inhibit the SK-BR-3 growth at a rate of 36.63 and 46.34% in 48 and 72 hr incubation separately, which was similar to trastuzumab (43.12 and 49.14% separately). These findings suggested that it was an effective method to select antibody mimetic DARPin by bacteria surface display combined with live cells sorting and provided a drug candidate for cancer therapy.

MiR-1268b confers chemosensitivity in breast cancer by targeting ERBB2-mediated PI3K-AKT pathway

Chemoresistance represents a major obstacle to effective therapy for breast cancer. Emerging evidences associated aberrantly expressed miRNAs with tumor development and chemoresistance. MiR-1268b has never been studied in any cancers before, and its roles in mediating tumor progression and drug resistance are still unclear. Selected from miRNA microarray and confirmed by real-time quantitative PCR (RT-qPCR), miR-1268b was found to be significantly upregulated in drug sensitive and ERBB2 negative tissues, as well as in breast cancer patients with low clinical stage. And miR-1268b had a higher expression in chemosensitive breast cancer cell lines, compared with the chemoresistant cell line. Moreover, the results revealed that miR-1268b induced breast cancer cell apoptosis and increased cell chemosensitivity. ERBB2 was demonstrated to be the target gene of miR-1268b by dual-luciferase reporter assays, western blot, and immunocytochemistry. Furthermore, PI3KCA, AKT, BCL2 in the ERBB2-PI3K-AKT signaling pathway were found to be downstream effectors of miR-1268b. In conclusion, miR-1268b increased chemosensitivity, at least in part, via modulation of PI3K-AKT pathway by targeting ERBB2. MiR-1268b may serve as a potential therapeutic target for patients with breast cancers.

Development and Characterization of a Humanized Anti-HER2 Antibody HuA21 with Potent Anti-Tumor Properties in Breast Cancer Cells

Human epidermal growth factor receptor 2 (HER2) is one of the most studied tumor-associated antigens for cancer immunotherapy. An engineered anti-HER-2 chimeric A21 antibody (chA21) is a chimeric antibody targeted to subdomain I of the HER2 extracellular domain. Here, we report the anti-tumor activity of the novel engineered monoclonal antibody humanized chA21 (HuA21) that targets HER2 on the basis of chA21, and we describe the underlying mechanisms. Our results reveal that HuA21 markedly inhibits the proliferation and migration of HER2-overexpressing breast cancer cells and causes enhanced antibody-dependent cell-mediated cytotoxicity potency against HER2-overexpressing tumor cells. In particular, HuA21, but not trastuzumab (Tra), markedly suppresses growth and enhances the internalization of the antibody in Tra-resistant BT-474 breast cancer cells. These characteristics are highly associated with the intrinsic ability of HuA21 to down-regulate HER2 activation and inhibit the extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (Akt) signaling pathways. Furthermore, the combination of HuA21 with Tra synergistically enhances the anti-tumor effects in vitro and in vivo and inhibits HER2 activation and the ERK1/2 and Akt signaling pathways. Altogether, our results suggest that HuA21 may represent a unique anti-HER2 antibody with potential as a therapeutic candidate alone or in combination with other anti-HER2 reagents in cancer therapy.

In vitro assessment of the effects of anti-HER2 monoclonal antibodies on proliferation of HER2-overexpressing breast cancer cells

BACKGROUND

HER2 proto-oncogene is critical in the biology of breast cancer and an important therapeutic target of monoclonal antibodies (mAbs). We have recently established a panel of anti-HER2 mAbs recognizing different epitopes within the extracellular domain of HER2.

MATERIALS & METHODS

In the present study the antiproliferative effect of these mAbs was investigated on HER2-overexpressing human breast cancer cell line BT474, using radioactive thymidine incorporation assay.

RESULTS

Our results demonstrated that while two of the mAbs (1T0 and 2A8) inhibited cell proliferation dose dependently, similar to trastuzumab, six mAbs (1F2, 1B5, 1H9, 4C7, 1H6 and 2A9) augmented cell proliferation. Treatment of BT474 cells with different combinations of two mAbs induced either synergistic inhibitory or stimulatory effects.

DISCUSSION

Our findings indicate that combination of some stimulatory mAbs could completely abolish the inhibitory effect of other mAbs against HER2. Employment of some combinations of mAbs with significant synergistic inhibitory function may improve the therapeutic efficacy of HER2-specific mAbs.

In vivo hyperspectral imaging of microvessel response to trastuzumab treatment in breast cancer xenografts

HER2-amplified (HER2 + ) breast cancers are treated with the anti-HER2 monoclonal antibody trastuzumab. Although trastuzumab reduces production of the angiogenic factor VEGF in HER2 + tumors, the acute and sustained effects of trastuzumab on the tumor vasculature are not understood fully, particularly in trastuzumab-resistant tumors. We used mouse models of trastuzumab sensitive and trastuzumab-resistant HER2 + breast cancers to measure dynamic changes in tumor microvessel density and hemoglobin oxygenation (sO2) in vivo using quantitative hyperspectral imaging at 2, 5, 9, and 14 days after antibody treatment. Further analysis quantified the distribution of microvessels into low and high oxygenation groups, and monitored changes in these distributions with trastuzumab treatment. Gold standard immunohistochemistry was performed to validate complementary markers of tumor cell and vascular response to treatment. Trastuzumab treatment in both responsive and resistant tumors resulted in decreased sO2 5 days after initial treatment when compared to IgG-treated controls (p<0.05). Importantly, responsive tumors showed significantly higher vessel density and significantly lower sO2 than all other groups at 5 days post-treatment (p<0.05). Distribution analysis of vessel sO2 showed a significant (p<0.05) shift of highly oxygenated vessels towards lower oxygenation over the time-course in both trastuzumab-treated responsive and resistant tumors. This study suggests that longitudinal hyperspectral imaging of microvessel sO2 and density could distinguish trastuzumab-responsive from trastuzumab-resistant tumors, a finding that could be exploited in the post-neoadjuvant setting to guide post-surgical treatment decisions.

Construction and evaluation of a novel humanized HER2-specific chimeric receptor

Introduction

The human epidermal growth factor receptor 2 (HER2) represents one of the most studied tumor-associated antigens (TAAs) for cancer immunotherapy. The monoclonal antibody (mAb) trastuzumab has improved the outcomes of patients with HER2+ breast cancer. However, a large number of HER2+ tumors are not responsive to, or become resistant to, trastuzumab-based therapy, and thus more effective therapies targeting HER2 are needed.

Methods

HER2-specific T cells were generated by the transfer of genes that encode chimeric antigen receptor (CAR). Using a multistep overlap extension PCR method, we constructed a novel, humanized HER2 CAR-containing, chA21 single-chain variable fragment (scFv) region of antigen-specific mAb and T-cell intracellular signaling chains made up of CD28 and CD3ζ. An interferon γ and interleukin 2 enzyme-linked immunosorbent assay and a chromium-51 release assay were used to evaluate the antitumor immune response of CAR T cells in coculture with tumor cells. Furthermore, SKBR3 tumor–bearing nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice were treated with HER2 CAR T cells to evaluate antitumor activity. Human CD3+ T cell accumulation in tumor xenograft was detected by immunohistochemistry.

Results

chA21-28z CAR was successfully constructed, and both CD4+ and CD8+ T cells were transduced. The expanded HER2 CAR T cells expressed a central memory phenotype and specifically reacted against HER2+ tumor cell lines. Furthermore, the SKBR3 tumor xenograft model revealed that HER2 CAR T cells significantly inhibited tumor growth in vivo. Immunohistochemical analysis showed robust accumulation of human CD3+ T cells in regressing SKBR3 lesions.

Conclusions

The results of this study show that novel chA21 scFv-based, HER2-specific CAR T cells not only recognized and killed HER2+ breast and ovarian cancer cells ex vivo but also induced regression of experimental breast cancer in vivo. Our data support further exploration of the HER2 CAR T-cell therapy for HER2-expressing cancers.

Construction and characterization of a new chimeric antibody against HER2

Aim: Immunotherapy with anti-HER2 antibodies has shown promising results in patients with HER2-positive breast cancer. We have recently reported characterization of a mouse monoclonal antibody (mAb) against HER2, which binds to an epitope different from that recognized by trastuzumab and specifically inhibits proliferation of tumor cells overexpressing HER2. In the present study we report chimerization of this antibody. Materials & methods: The immunoglobulin variable region heavy and light chain genes of 1T0 hybridoma cells were amplified and ligated to human γ-1 and κ constant region genes using splice overlap extension PCR. The chimeric antibody was subsequently expressed and characterized by ELISA, western blot and flow cytometry. Results: The purified chimeric antibody specifically binds to recombinant HER2 and HER2-overexpressing tumor cells and inhibits proliferation of these cells. The binding affinity of the chimeric mAb was comparable with the parental mouse mAb. Conclusion: This chimeric anti-HER2 mAb is a potentially valuable tool for targeted immunotherapy.

A human Fab-based immunoconjugate specific for the LMP1 extracellular domain inhibits nasopharyngeal carcinoma growth in vitro and in vivo

Nasopharyngeal carcinoma (NPC) is a major cause of cancer-related death in Southeast Asia and China. Metastasis and relapse are the primary cause of morbidity and mortality in NPC. Recent evidence suggests that the Epstein-Barr virus latent membrane protein 1 (LMP1) is exclusively expressed in most NPC and is a potential target for biotherapy. In this study, we successfully prepared a novel human antibody Fab (HLEAFab) against LMP1 extracellular domain, which was subsequently conjugated with mitomycin C (MMC), thus forming an immunoconjugate (HLEAFab-MMC). The effects of HLEAFab-MMC on proliferation and apoptosis in NPC cell lines HNE2/LMP1 and the inhibition rate of growth of NPC xenografts in nude mice were examined. The inhibition rate of HNE2/LMP1 cell proliferation was the highest for HLEAFab-MMC (76%) compared with MMC (31%) and HLEAFab (22%) at a concentration of 200 nmol/L and showed dose-dependent fashion. The apoptosis rate of HNE2/LMP1 cell lines was 13.88% in HLEAFab-MMC group, 3.04% in MMC group, 2.78% in HLEAFab group, and 2.10% in negative control group at the same concentration, respectively. In vivo, the inhibition rate of growth of NPC xenografts in nude mice was 55.1% in HLEAFab-MMC group, 26.5% in MMC group, and 5.64% in HLEAFab group. In summary, our findings show that HLEAFab-MMC is a unique immunoconjugate with the potential as a novel therapeutic agent in the treatment of LMP1-expressing NPC.

Structural insights into the down-regulation of overexpressed p185(her2/neu) protein of transformed cells by the antibody chA21

p185(her2/neu) belongs to the ErbB receptor tyrosine kinase family, which has been associated with human breast, ovarian, and lung cancers. Targeted therapies employing ectodomain-specific p185(her2/neu) monoclonal antibodies (mAbs) have demonstrated clinical efficacy for breast cancer. Our previous studies have shown that p185(her2/neu) mAbs are able to disable the kinase activity of homomeric and heteromeric kinase complexes and induce the conversion of the malignant to normal phenotype. We previously developed a chimeric antibody chA21 that specifically inhibits the growth of p185(her2/neu)-overexpressing cancer cells in vitro and in vivo. Herein, we report the crystal structure of the single-chain Fv of chA21 in complex with an N-terminal fragment of p185(her2/neu), which reveals that chA21 binds a region opposite to the dimerization interface, indicating that chA21 does not directly disrupt the dimerization. In contrast, the bivalent chA21 leads to internalization and down-regulation of p185(her2/neu). We propose a structure-based model in which chA21 cross-links two p185(her2/neu) molecules on separate homo- or heterodimers to form a large oligomer in the cell membrane. This model reveals a mechanism for mAbs to drive the receptors into the internalization/degradation path from the inactive hypophosphorylated tetramers formed dynamically by active dimers during a "physiologic process."