Monoclonal HER2 Research Articles

ACE-Breast-02: A pivotal phase II/III trial of ARX788, a novel anti-HER2 antibody-drug conjugate (ADC), versus lapatinib plus capecitabine for HER2+ advanced breast cancer (ABC).

1020 Background: ARX788 is a next-generation ADC of HER2 monoclonal antibody site-specifically conjugated with Amberstatin 269, a potent cytotoxic tubulin inhibitor. Here we report the interim result from this seamless phase II/III trial in patients who progressed on trastuzumab based therapy. Methods: This randomized study was conducted in HER2+ (FISH+ or IHC3+) ABC in 85 centers in China. Patients with unresectable or metastatic breast cancer pretreated with trastuzumab and taxane were randomized 1:1 to receive ARX788 (1.5mg/kg, IV, Q3W) or lapatinib plus capecitabine (LC, lapatinib 1250mg, QD; capecitabine 1000mg/m2 BID, d1-14, Q3W), stratified by previous chemotherapy lines (0-1 vs. >1) and visceral metastasis (yes vs. no). ARX788 was not pre-medicated with any prophylactic measures. Primary endpoint was progress-free survival (PFS) determined by Independent Review Committee (IRC). Results: As of Dec. 21, 2022, 221 patients were randomly assigned to ARX788 and 220 to LC, and 240 PFS events occurred. Efficacy results are listed in table 1. The median PFS was 11.33 months with ARX788 versus 8.25 months with LC as per IRC (HR 0.64, p=0.0006). Treatment-related adverse events (TRAEs) of any grade occurred in 98.6% (217/220) and 99.1% (213/215) of patients, respectively. TRAEs of grade 3-5 was similar in two groups (41.4% and 40.0%, respectively), commonest being blurred vision (12.3%), dry eye (9.1%), keratopathy (5.9%) and interstitial lung disease (5.9%) with ARX788 and hand-foot syndrome (18.1%), hypokalemia (5.1%), diarrhea (4.2%) with LC. 71 patients (32.3%) had interstitial lung disease with ARX788, primarily grade 1 or 2 (26.8%) with 3 (1.4%) possibly having drug-related deaths. 164 patients (74.5%) had ocular events related to ARX788, primarily grade 1 or 2 (55.5%) with no grade 4 or 5. Conclusions: ARX788 significantly prolonged PFS comparing to LC in patients with HER2+ ABC previously treated with trastuzumab and taxane. While ocular toxicity and interstitial lung disease were common and manageable, its hematological and GI toxicities under no prophylactic premedication compared favorably with already available ADCs. Clinical trial information: CTR20201708. [Table: see text]

A prospective, open-label, single-arm phase II clinical study of inetetamab in combination with pyrotinib and albumin-bound paclitaxel for the neoadjuvant treatment of patients with HER2+ early and locally advanced breast cancer.

e12635 Background: Chemotherapy combined with dual anti-HER2 target therapy has become the standard neoadjuvant therapy regimen for HER2+ breast cancer. Patients achieving pCR have a relatively better prognosis. Inetetamab (Septin) is an innovative HER2 monoclonal antibody drug developed in China. It has been proven to delay the progression of HER2+ metastatic breast cancer patients and bring survival benefits. The purpose of this study was to explore the efficacy and safety of Inetetamab, Pyrotinib and Albumin-bound Paclitaxel in the neoadjuvant treatment of HER2+ breast cancer. Methods: This phase II trial included patients with HER2+ early or locally advanced breast cancer whose tumor size was>20mm or confirmed axillary lymph node metastasis. Patients receive Inetetamab initial dose of 8 mg/kg over 90 minutes IV infusion, followed 6 mg/kg over 30 to 90 minutes IV infusion q3w, Pyrotinib 400 mg orally every day and Albumin-bound Paclitaxel 125mg/m2, IV, D1/8/15, q3w. Patients receive above treatment every 3 weeks for a total of 4 cycles, followed by surgery. After surgery, EC (90mg/m2 of Epirubicin Hydrochloride, 600mg/m2 of Cyclophosphamide, q21 days, 4 cycles) was administered, followed by maintenance treatment with trastuzumab combined with pertuzumab for 1 year. And provide radiotherapy and endocrine therapy to the patient according to the specific situation. The primary endpoint was pathological complete response (pCR). Results: Until February 4, 2024, 18 patients were enrolled, of which 15 had completed surgical treatment. The median age of enrolled patients was 49 years (35-60 years). 66.7% (10 cases) of patients achieved RCB grade 0 (pCR), 26.7% (4 cases) achieved RCB grade I, 6.7% (1 case) achieved RCB grade II. Of the 15 patients, 73.3% (11 cases) were HR+/HER2+, with 72.7% (8 cases) achieved pCR. Among the 4 HR-/HER2+ patients, 50% (2 case) achieved pCR. HR+/HER2+ patients were more likely to achieve pCR than HR-/HER2+ patients. No severe (grade 3/4) toxicity was observed in any patients. Conclusions: Our current data show that the pCR rate in HER2+ breast cancer patients reaches 66.7%, and even 72.7% in HR+ patients. In the previous Neosphere and PEONY studies of the H+P dual target regimen, the pCR of HR+/HER2+patients increased by only 6% and 8.3%, while in the NeoALTTO and PHEDRA studies of the H+L or H+Py regimen, the pCR increased by 18.9% and 17.7%, indicating that the combination of large and small molecules with dual target neoadjuvant therapy for HR+/HER2+ breast cancer was significantly better than that of the monoclonal antibody dual target therapy. Therefore, Inetetamab, Pyrotinib and albumin-bound paclitaxel is a potential effective new adjuvant treatment for HER2+ breast cancer, especially for HR+ patients. Clinical trial information: NCT054444998 .

Hypofunction of macrophage chemotaxis contributes to defective efficacy of herceptin in HER2-positive breast cancer patients

ABSTRACT Breast cancer was considered as a kind of prone breast tumors with the complicated pathological mechanisms and diverse clinical classifications. In the clinical treatments of HER2-positive tumor patients, HER2 monoclonal antibodies, such as Herceptin, have shown well-defined therapeutic effects. Nevertheless, due to the heterogeneity of breast cancers, drug resistance inevitably appeared during the application of Herceptin. In order to fully understand the immune tolerance status of the tumor microenvironment in the population of sensitive and insensitive patients, this study carried out a series of studies through Luminex cytokines assay, clinicopathological analysis, immunofluorescence, and PCR. The results confirmed that in clinical samples sensitive to Herceptin, there were a large number of macrophages, and the protein expression levels and in situ expression of macrophage-related chemokines and inflammatory mediators are significantly higher than drug-resistant tumor samples. Further studies found that T cell function has a low correlation with tumor growth, and there are obvious obstacles in the process of peripheral blood immune cells entering the tumor microenvironment. In summary, this study provided clues for understanding the clinical drug resistance of HER2 monoclonal antibody and the clinical rational use of drugs and combination drugs.

Abstract A149: Characterization of HER3 targeted radioligand therapy using molecular imaging

Abstract Background: Radioligand therapy (RLT) is an emerging treatment modality that has shown potential to improve survival in cancer patients that often have limited or non-effective therapeutic options. We previously demonstrated that anti-HER3 antibody radioconjugate (HER3 ARC) has antitumor efficacy against HER3 expressing tumor xenograft models. One important step in the early development of RLT is to understand the targeting properties and the distribution of the RLT in vivo. Non-invasive molecular imaging such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) offer unique opportunities to understand drug behavior in vivo, permitting real time drug targeting and distribution analysis. In this study, we assessed the targeting properties and distribution of our HER3 ARC in HER3 expressing preclinical xenograft tumor models using both SPECT and PET. Methods: HER3 monoclonal antibody was conjugated with p-SCN-Bn-deferoxamine (DFO) or p-SCN-Bn-DOTA (DOTA) then labeled with Zirconium-89 (89Zr) or Indium-111 (111In), respectively. Flow cytometry and gamma counting was used to characterize HER3 ARC biological activity in HER3-expressing tumor cell lines. Balb/c mice subcutaneously inoculated with HER3-expressing xenograft tumors (lung, ovarian and colorectal) were intravenously administered with 89Zr-DFO-HER3 or 111In-DOTA-HER3. PET or SPECT scans were acquired 72 and 120-144hrs post injection of the radiotracer. Separate cohorts of mice were simultaneously administered with 89Zr-DFO-HER3 or 111In-DOTA-HER3 and 20-fold excess of native HER3 antibody as control to block radiotracer binding. Tissue uptake was quantified by drawing 3D or 2D regions of interest (ROI) for PET or SPECT images, respectively. Results: HER3 ARC radiotracers were successfully prepared and demonstrated similar binding to HER3 expressing cells compared to native HER3 antibody. In tumor-bearing mice, 89Zr-DFO-HER3 and 111In-DOTA-HER3 specifically accumulated in HER3 expressing tumors and cleared throughout the reticuloendothelial system. High tumor uptake was observed 120hrs post radiotracer injection using both imaging modalities. In mice pre-treated with 20-fold excess of native antibody, tumor uptake was significantly lower, showing tumor binding specificity of ARC. PET and SPECT images showed similar tracer distribution profile in the HER3 tumors. As expected, radiotracer clearance organ signals were also visualized. Conclusions: In this study we show that PET or SPECT imaging using 89Zr or 111In, respectively, offers the potential to assess the distribution of HER3 targeted radioligand therapy during early stages of drug development. HER3 ARC showed highly specific HER3 tumor uptake that remained at least 120hrs post injection. Our findings warrant further investigation to support advancement of HER3 ARC as a therapeutic option. Citation Format: Sumit Mukherjee, Debbie Lewis, Jason Li, Le-Cun Xu, Amanda Chin, Mary Chen, Monideepa Roy, Patrik Brodin, William van der Touw, Helen Kotanides, Denis Beckford-Vera. Characterization of HER3 targeted radioligand therapy using molecular imaging [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A149.

Development of Highly Sensitive Anti-Mouse HER2 Monoclonal Antibodies for Flow Cytometry

Overexpression of human epidermal growth factor receptor 2 (HER2) in breast cancer is an important target of monoclonal antibody (mAb) therapy such as trastuzumab. Due to the development of trastuzumab–deruxtecan, an antibody-drug conjugate, the targetable HER2-positive breast cancer patients have been expanded. To evaluate the developing modalities using anti-HER2 mAbs, reliable preclinical mouse models are required. Therefore, sensitive mAbs against mouse HER2 (mHER2) should be established. This study developed anti-mHER2 mAbs using the Cell-Based Immunization and Screening (CBIS) method. The established anti-mHER2 mAbs, H2Mab-300 (rat IgG2b, kappa) and H2Mab-304 (rat IgG1, kappa), reacted with mHER2-overexpressed Chinese hamster ovary-K1 (CHO/mHER2) and endogenously mHER2-expressed cell line, NMuMG (a mouse mammary gland epithelial cell) via flow cytometry. Furthermore, these mAbs never recognized mHER2-knockout NMuMG cells. The kinetic analysis using flow cytometry indicated that the dissociation constant (KD) values of H2Mab-300 and H2Mab-304 for CHO/mHER2 were 1.2 × 10−9 M and 1.7 × 10−9 M, respectively. The KD values of H2Mab-300 and H2Mab-304 for NMuMG were 4.9 × 10−10 M and 9.0 × 10−10 M, respectively. These results indicated that H2Mab-300 and H2Mab-304 could apply to the detection of mHER2 using flow cytometry and may be useful to obtain the proof of concept in preclinical studies.

Construction of Gene-Targeted Polymeric Microvesicles and Their In Vitro Targeted Binding Ability to Human Epidermal Growth Factor Receptor 2 (+) Breast Cancer Cells

The objective of this research was to construct the gene-targeted polymeric microvesicles (PMVs) and investigate their In Vitro ability to bind specifically to human epidermal growth factor receptor 2 (HER-2) (+) breast cancer (BC) cells. PMVs were formed using a block copolymer, methoxy polyethylene glycol-poly(L-lactide) (mPEG-PLLA), as the shell and encapsulating liquid perfluoropentane. Plasmid DNA and biotinylated HER-2 monoclonal antibody were conjugated to form the gene-loaded HER-2-targeted PMVs for BC cells. The characterization, physicochemical properties, and antibody coupling efficiency of the PMVs were evaluated. The PMVs were then co-cultured with HER-2 (+) BT474 cells, and their ability to target and bind to HER-2 (+) BC cells was observed under a microscope. Results revealed that the average particle size (APS) of the gene-targeted PMVs was (3.92±1.01) μm, with a uniform particle size distribution (PSD), smooth and transparent surfaces, and superior stability. The fluorescence intensity (FI) of PMVs in Group A was higher (16 vs. 9) to that in Group B, indicating a high binding rate (BR) (97.01%) between the PMVs and HER-2 monoclonal antibody. BT474 cells exhibited green fluorescence on their surface, which was stronger than that observed in SK-BR-3 cells, while no obvious green fluorescence was visualized in MDA-MB-231 cells or Hs578Bst cells. PMVs in Group A presented extensive binding to BT474 cells, mainly distributed on the cell membrane and surrounding areas. Only a few PMVs in Groups B and C were observed to bind to BT474 cells. In conclusion, the gene-loaded HER-2-targeted PMVs exhibited excellent stability and high specificity for binding to HER-2 (+) BC cells In Vitro, suggesting their potential application value.

Targeted and Immunotherapy Approaches in HER2-Positive Gastric and Gastroesophageal Junction Adenocarcinoma: A New Era.

HER2-targeted therapy with the HER2 monoclonal antibody trastuzumab has achieved impressive outcomes in the first-line settings of patients with advanced gastric and gastroesophageal junction (GEJ) adenocarcinoma overexpressing HER2. However, considering that a substantial proportion of those patients eventually relapses, as well as the relatively limited performance of those agents in second-line settings, a deeper understanding of resistance mechanisms is needed for enhanced guidance for patients' therapeutic selection in the second-line setting and beyond. In this review, we highlight trastuzumab's (HER2-targeting agent) performance in patients with gastric or GEJ cancer, with insight into mechanisms of resistance. We also discuss the new integration of PD-1 inhibitor pembrolizumab into the trastuzumab for gastric cancer frontline regimen, the latest addition of trastuzumab deruxtecan to the treatment armamentarium, and the potential of pipeline HER2-targeting approaches and combinations in patients with gastric or GEJ adenocarcinoma.

ERBB2 (HER2) gene amplification concordance analysis of circulating tumor cells and tumor tissue in patients with breast cancer.

e13047 Background: HER2 targeted therapies, such as HER2 monoclonal antibodies, HER2 tyrosine kinase inhibitors, and HER2 antibody drug conjugates, are approved for the treatment of HER2-positive breast, gastric and colorectal cancers. However, inter- and intra-tumoral heterogeneity in HER2 status presented a significant challenge in identifying patients that may benefit from HER2-targeted therapies. Detection of ERBB2 amplification in Circulating Tumor Cells (CTCs) may circumvent tissue heterogeneity issues and effectively predict the response of patients to anti-HER2 agents as a non-invasive alternative approach. Methods: A twenty-four patient pilot study was designed to compare HER2 status of traditional needle biopsies to high sensitivity CTC based liquid biopsies. HER2 status was determined using immunohistochemistry (IHC) and Fluorescence in Situ Hybridization (FISH) for tissue samples and FISH analysis for CTCs. Currently 21 patient samples have been compared in this study. Results: CTCs with HER2 amplified signals were found in patients with stages 2, 3, or 4 breast cancers. Based on the biopsies of the primary tumor or metastatic disease, 6 patients (29%) had HER2-overexpressing as defined by either HER2 IHC 3+ or HER2 FISH amplified. Analysis of CTCs showed 100% concordance (HER2 amplification detected in CTCs) in these patients with HER2-overexpressing breast cancer. Furthermore, an additional 4 (19%) patients had HER2 amplification by CTC analysis but not on needle biopsy. Conclusions: Our finding demonstrates that LiquidScan can be used as a rapid analysis tool to evaluate HER2 amplification in CTCs. This approach can potentially help identify additional cohort of patients (HER2 non-amplified tumor / HER2 amplified CTCs) who may benefit from the new generation of HER2 targeted therapies. Studies are ongoing to include an expanded cohort of patients with early stage disease, as well as HER2-low disease, in order to evaluating dynamics of ERBB2 gene amplification, expression, and pathway activation while on active systemic therapy.

A phase II study of concurrent WOKVAC vaccination with neoadjuvant chemotherapy and HER2-targeted monoclonal antibody therapy.

TPS636 Background: HER2+ breast cancer (BCa) is an aggressive breast cancer subtype. The treatment of Stage I-III HER2+ BCa with neoadjuvant chemotherapy and HER2 monoclonal antibodies (trastuzumab and pertuzumab) induces a pathologic complete response in 43-67% of patients. Residual HER2+ disease (i.e. residual cancer burden) after neoadjuvant therapy is associated with a significantly higher risk of recurrence. Evidence supports that HER2 immunity is progressively lost in HER2 oncogenesis and that restoration of HER2 specific CD4+ Th1 immunity is associated with a lower risk of recurrence. Trastuzumab can partially restore HER2 specific immunity, but only in a minority of patients. We have demonstrated that HER2 specific vaccination can augment HER2 specific immunity. While taxane chemotherapy can deplete immunosuppressive cells (MDSCs) 13 – 17 days after treatment creating an optimal time for vaccination. The WOKVAC vaccine is a plasmid vaccine encoding Th1 selective epitopes from HER2 and two other high-risk cancer antigens IGFBP-2 and IGF-1R. The Phase I trial of this vaccine reported that it is safe and all doses induced antigen specific Type I immune responses. We hypothesize that addition of WOKVAC to neoadjuvant chemo/HER2 targeted therapy will induce a significant increase in the number of patients with Th1 CD4+ and CD8+ T cells after neoadjuvant vaccine/chemo/HER2 therapy. Methods: Trial Design: Phase II single arm trial of WOKVAC vaccination with concurrent neoadjuvant taxane based chemotherapy, trastuzumab, and pertuzumab in patients with Stage I-III HER2+ (HR+/-) breast cancer. Enrolled patients will receive WOKVAC vaccine 150mcg on day 13 of cycles 1-3. WOKVAC vaccination may be given with either TCHP or THP. A maximum of 16 patients will be enrolled in this study. Objectives: The primary objective is to evaluate whether concurrent WOKVAC vaccine with chemotherapy and HER2 antibody therapy can significantly increase T-bet+ CD4+ and CD8+ TIL. Secondary objectives are to determine: (1) whether concurrent WOKVAC with neoadjuvant chemo/HER2 therapy is safe, (2) if the magnitude of vaccine induced antigen specific Th1 immunity after neoadjuvant therapy is associated with pathologic response. Statistical Methods: (1) In order to detect a 30% increase in the number of patients with Tbet+ CD4+ and CD8+ TIL in the enrolled patients with 80% power and a one-side alpha of 0.05, our enrollment goal for this study will be 16 patients. (2) Safety will be assessed per CTCAE v5.0, Benchmarks for safety needed to advance this trial concept to a Phase III study will be a grade 3 toxicity rate of ≤13% and a grade 4 toxicity rate of ≤ 7%. (3) The induction of Th1 immunity will be compared against the presence or absence of a complete pathologic response to determine if there is a significant correlation using Pearson r correlation analysis. Targeted Accrual: The study will accrue up to 16 patients. Clinical trial information: NCT04329065 .

Immunohistochemical Expression Of Human Epidermal Growth Factor Receptor-2 (Her-2) In Common Salivary Gland Carcinomas.

Carcinomas of the salivary gland are known to be aggressive in nature, making them difficult to manage. The therapeutic options offered include excision of the gland (maxillectomy in cases of palatal tumours), with or without lymph node dissection, proceeded with radiotherapy. Chemotherapy has not produced promising outcomes and has a minimal impact as a therapeutic alternative. Targeted therapy against human epidermal growth factor receptor 2 (HER-2), which is a commonly used treatment modality for their mammary analogues, is not being offered to these patients since scant literature is available showing its usefulness and no promising evidence is present regarding their efficacy and efficiency in such cases. The study aimed to evaluate and quantify the immunohistochemical expression of HER-2 in cases of adenoid cystic carcinoma (AdCC), mucoepidermoid carcinoma (MEC) and salivary duct carcinoma (SDC), which are analogues of similar tumours arising in breast tissue. A retrospective, cross-sectional study was carried out in the department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi, duration of which was six months. A total of 45 cases (15 of each tumour) were taken, and sampled using non-probability convenience technique. The immunohistochemical marker, monoclonal HER-2 antibody (Leica microsystem Germany) was applied on appropriate blocks of all included cases. The staining pattern and intensity were recorded after visualizing the slides under a light microscope. Seven cases of salivary duct carcinoma and a single case of mucoepidermoid carcinoma expressed positivity for HER-2, while no expression could be seen in the case of adenoid cystic carcinoma. A statistically significant difference was seen when HER-2 expression was compared among the aforementioned tumours. The use of targeted therapy against HER-2 is limited to patients of salivary duct carcinoma and a fraction of patients suffering from mucoepidermoid carcinoma.

PTX3 from vascular endothelial cells contributes to trastuzumab-induced cardiac complications.

Trastuzumab, the first humanized monoclonal antibody that targets human epidermal growth factor receptor 2 (ERBB2/HER2), is currently used as a first-line treatment for HER2 (+) tumours. However, trastuzumab increases the risk of cardiac complications without affecting myocardial structure, suggesting a distinct mechanism of cardiotoxicity. We used medium from trastuzumab-treated human umbilical vein endothelial cells (HUVECs) to treat CCC-HEH-2 cells, the human embryonic cardiac tissue-derived cell lines, and human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) to assess the crosstalk between vascular endothelial cells (VECs) and cardiomyocytes. Protein mass spectrometry analysis was used to identify the key factors from VECs that regulate the function of cardiomyocytes. We applied RNA-sequencing to clarify the mechanism, by which PTX3 causes cardiac dysfunction. We used an anti-human/rat HER2 (neu) monoclonal antibody to generate a rat model that was used to evaluate the effects of trastuzumab on cardiac structure and function and the rescue effects of lapatinib on trastuzumab-induced cardiac side effects. Medium from trastuzumab-treated HUVECs apparently impaired the contractility of CCC-HEH-2 cells and iPSC-CMs. PTX3 from VECs caused defective cardiomyocyte contractility and cardiac dysfunction in mice, phenocopying trastuzumab treatment. PTX3 affected calcium homoeostasis in cardiomyocytes, which led to defective contractile properties. EGFR/STAT3 signalling in VECs contributed to the increased expression and release of PTX3. Notably, lapatinib, a dual inhibitor of EGFR/HER2, could rescue the cardiac complications caused by trastuzumab by blocking the release of PTX3. We identified a distinct mode of cardiotoxicity, wherein the activation of EGFR/STAT3 signalling by trastuzumab in VECs promotes PTX3 excretion, which contributes to the impaired contractility of cardiomyocytes by inhibiting cellular calcium signalling. We confirmed that lapatinib could be a feasible preventive agent against trastuzumab-induced cardiac complications and provided the rationale for the combined application of lapatinib and trastuzumab in cancer therapy.

Her2low breast cancer. New opportunities and challenges

Background. Breast cancer is an increasingly prevalent cancer pathology. In developed countries, breast cancer hits almost every eighth woman and ranks first in the incidence of patients with malignant tumors. The success of breast cancer therapy is apparently connected with the effectiveness of a strategy of impact on typical breast cancer targets, such as estrogen and progesterone receptors, HER2/neu oncoprotein. Implementation of modern achievements of fundamental science into routine clinical practice will allow the prognosis of patients with breast cancer at both earlier and later stages (in cases of the metastatic lesion) to be improved.
 Purpose. To review modern literature sources that cover biological and clinical relevance of expanding molecular genetic classification of breast cancer for the purpose of singling out additional clinically significant breast cancer subtypes with special emphasis on HER2-low-positive tumors.
 Materials and methods. The literature search was performed manually by the keywords (breast cancer, HER2-low-positive breast cancer), and also literature sources from evidential databases PubMed, and Web of Science were reviewed. The data from meta-analyses, randomized trials, systematic reviews, cohort trials, and the data of fundamental works were taken into consideration. 41 literature sources were analyzed in total. We opted for the sources which were published over the last ten years.
 Results. Breast cancer is a heterogeneous disease. Overexpression of the HER2 receptor is peculiar to 15–20% of breast tumors, usually due to amplification of the ERBB2 gene. Taking into account that the ERBB2 gene is a very powerful proto-oncogene, tumors with such phenotype are characterized by aggressive course and unfavorable prognosis. Starting from the 1990s, the development of target drugs aimed at the blockade of HER2 receptors beginning from monoclonal antibodies – trastuzumab, later – pertuzumab, tyrosine kinase inhibitors (lapatinib, neratinib, tucatinib) and the new class of antitumor drugs – conjugates of a monoclonal antibody with a cytostatic drug (trastuzumab emtansine, trastuzumab deruxtecan, trastuzumab duocarmazine) and their implementation into clinical practice changed the course and the prognosis of the patients with HER2-positive breast cancer. In opposition to earlier clinical trials, the results of the more modern ones demonstrate the clinical effectiveness of new antitumor drugs such as conjugates of HER2 monoclonal antibody with a cytostatic drug (trastuzumab deruxtekan, trastuzumab duokarmazine) not only in patients with HER2-positive breast cancer but also in some patients with metastatic breast cancer with low HER2 expression. In order to determine the patients who may potentially benefit from the new target drugs among the patients with HER2-negative breast cancer, a new concept of HER2/neu-low breast cancer has been suggested, which is used for the selection of patients in modern clinical trials, and in the measurable future it will be used in routine clinical practice.
 Conclusions. Today’s scientific data confirm biological and clinical relevance of expanding molecular genetic classification of breast cancer for the purpose of singling out additional clinically significant breast cancer subtypes with special emphasis on HER2-low-positive tumors. The development of a new class of antitumor drugs, namely conjugates of HER2 monoclonal antibody with a cytostatic drug (trastuzumab deruxtekan, trastuzumab duokarmazine) gives new therapeutic possibilities for patients with breast cancer, and also for patients with other types of malignant tumors.

Development of the B cell cancer vaccine HER-vaxx for the treatment of her-2 expressing cancers.

Her-2/neu is a tumor-associated protein that is overexpressed in a number of malignancies, including advanced cancer of the stomach, and has been proposed as a human cancer vaccine target. Overexpression of Her-2/neu in human breast and gastric carcinomas correlates with a more aggressive course of disease that results in poorer overall survival rates and shorter times to disease progression than in patients with tumors without overexpression of Her-2/neu. Cancer vaccines have the ability to stimulate the native immune system and in particular engineered B cell epitopes can elicit high affinity polyclonal antibodies with similar efficacy to Her-2 monoclonal antibodies such as trastuzumab (Roche). HER-Vaxx is under development as a therapeutic B cell vaccine for the treatment of gastric cancer in patients with Her-2/neu overexpressing metastatic or advanced adenocarcinoma of the stomach or gastroesophageal junction, referred to as advanced cancer of the stomach. P467-CRM197, the vaccine's immunogenic component, contains a single peptide antigen composed of 3 individual linear B cell epitope peptide sequences selected from the oncoprotein Her-2/neu that induce the patient's own B cells to produce endogenous anti-Her-2/neu antibodies. This review provides results from comprehensive preclinical studies encompassing primary and secondary pharmacodynamics, biodistribution and safety studies. These studies were performed to support clinical development of HER-Vaxx. Results from the GLP toxicology study in rodents showed that the vaccine did not produce any observable adverse effects suggesting that the doses proposed for the clinical trial should be well tolerated in patients.

Prognostic value of comprehensive typing based on m6A and gene cluster in TNBC.

Triple-negative breast cancer (TNBC) is resistant to targeted therapy with HER2 monoclonal antibodies and endocrine therapy, because it lacks the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). TNBC is a subtype of breast cancer with the worst prognosis and the highest mortality rate compared to other subtypes. N6-methyladenosine (m6A) modification is significant in cancer and metastasis, because it can alter gene expression and function at numerous levels, such as RNA splicing, stability, translocation, and translation. There are limited investigations into the connection between TNBC and m6A. Breast cancer-related data were retrieved from the Cancer Genome Atlas (TCGA) database, and 116 triple-negative breast cancer cases were identified from the data. The GSE31519 data set, which included 68 cases of TNBC, was obtained from the Gene Expression Omnibus (GEO) database. Survival analysis was used to determine the prognosis of distinct m6A types based on their m6A group, gene group, and m6A score. To investigate the potential mechanism, GO and KEGG analyses were performed on the differentially expressed genes. The expression of m6A-related genes and their impact on prognosis in TNBC patients were studied. According to the findings, m6A was crucial in determining the prognosis of TNBC patients, and the major m6A-linked genes in this process were YTHDF2, RBM15B, IGFBP3, and WTAP. YTHDF2, RBM15B and IGFBP3 are associated with poor prognosis, while WTAP is associated with good prognosis. By cluster analysis, the gene cluster and the m6A cluster were beneficial in predicting the prognosis of TNBC patients. The m6A score based on m6A and gene clusters was more effective in predicting the prognosis of TNBC patients. Furthermore, the tumor microenvironment may play an important role in the process of m6A, influencing TNBC prognosis. N6-adenylic acid methylation (m6A) was important in altering the prognosis of TNBC patients, and the key m6A-associated genes in this process were YTHDF2, RBM15B, IGFBP3, and WTAP. Furthermore, the comprehensive typing based on m6A and gene clusters was useful in predicting TNBC patients' prognosis, showing potential as valuable evaluating tools for TNBC.

Abstract P2-13-05: Central nervous system metastases as a site of first recurrence in adjuvant therapy trials of HER2+ early breast cancer (EBC)

Abstract Background: Among patients (pts) with HER2+ early breast cancer (EBC), the CNS continues to serve as a sanctuary for distant metastases following trastuzumab-based adjuvant treatment (von Minckwitz 2017, Piccart 2020, von Minckwitz 2019). Since the initial trastuzumab adjuvant trials, several other HER2-directed agents, including pertuzumab, lapatinib, ado-trastuzumab emtansine, and neratinib have been evaluated in EBC. We sought to describe the incidence of CNS metastases as a site of first recurrence in pts with HER2+ EBC who have received a HER2 directed agent, in order to evaluate whether there is any evidence of CNS prevention. Methods: A literature analysis was performed to identify controlled pivotal trials of HER2-directed adjuvant therapy in pts with HER2+ EBC and with or without prior neoadjuvant therapy. Data regarding CNS metastases as the first site of recurrence was extracted along with data from a meta-analysis of trastuzumab adjuvant trials. Due to differences in trial design, populations studied and differences in the use of neoadjuvant therapy, a descriptive summary of data is presented in lieu of statistical cross-trial comparisons. Results: Results from adjuvant trials of trastuzumab, lapatinib, neratinib, pertuzumab, and ado-trastuzumab emtansine in pts with HER2+ EBC (meta-analysis of trastuzumab trials, ALLTO, ExteNET, APHINITY and KATHERINE, respectively) are summarized (Table). In the trastuzumab adjuvant trials the incidence of CNS metastases was ~2.5% (Olson 2013). No pts had prior neoadjuvant therapy in APHINITY and neoadjuvant use was limited in ALLTO (8%). The addition of lapatinib, a reversible TKI, or pertuzumab, a HER2 monoclonal antibody, to trastuzumab had no impact on the incidence of CNS metastases. In the lapatinib and pertuzumab studies, the incidence of CNS metastases in all study groups was ~2%. The proportion of pts with CNS recurrence as a first site of metastasis among placebo pts in the ExteNET trial was similar to that reported in the other 3 trials (Table). Numerical improvements in the incidence of CNS as a site of first recurrence were seen in the intention-to-treat (ITT) population as well as in pts with hormone receptor positive (HR+) disease. The 5-year cumulative incidence of CNS metastases as a site of first recurrence in the ExteNET ITT population was 1.3% and in pts with HR+ disease who initiated neratinib ≤1 year post trastuzumab (HR+/≤1yr) was 0.7% (Table). The KATHERINE study, which enrolled higher risk patients, reported a higher incidence of CNS metastases as site of first recurrence, but without a reduction in the intervention arm (5.9% ado-trastuzumab emtansine and 4.3% trastuzumab). In a descriptive analysis of the subgroup of pts in ExteNET who were HR+/≤1yr and had residual disease after neoadjuvant therapy (n=295), the incidence of CNS metastases was 0.8% in the neratinib arm vs 3.6% in the placebo arm. Conclusions: The risk of developing a CNS metastasis as the site of first recurrence is generally low; however, it is higher in those with residual disease after neoadjuvant therapy. The ExteNET trial of neratinib is the only study to show a signal decrease in the incidence of CNS recurrence as the first site of relapse among HER2+ EBC pts. These data are consistent with other trials showing CNS activity with neratinib in the metastatic setting. CNS Recurrence as the First Site of Metastasis in Studies of Adjuvant Therapy in HER2+ EBCTrial and PopulationAnalysis TimepointNNeoadjuvant Population CNS Recurrence, %ComparatorTreatmentAdjuvant trast Meta-analysis1-9020N/A1.942.56ALLTO23 yr5190~822ExteNET3ITT5 yr284026%1.81.3HR+/≤1yr post trast.5 yr133427%2.10.7APHINITY4 node (+) or high-risk node ()3 yr480501.91.9No pCR Post Neoadjuvant TxKATHERINE5 high-risk3 yr1486N/A4.35.9ExteNET3 HR+/≤1yr post trast5 yr295N/A3.60.8HR+/≤1yr, hormone receptor positive with start of neratinib ≤1 year following trastuzumab adjuvant therapy; ITT, intent-to-treat; PLB, placebo; T-DM1, ado trastuzumab emtansine; trast, trastuzumab; pCR, pathologic complete responsea.Using all patients in the trials as a denominator1.Olson 2013; 2. Piccart-Gebhart 2015; 3. Chan 2021; 4. Von Minckwitz 2017; 5. Mamounas 2020 Citation Format: Nancy U Lin, Diana Lueftner, Adam M Brufsky, Sara M Tolaney, Michelle E Melisko, Frankie Ann Holmes, Ahmad Awada. Central nervous system metastases as a site of first recurrence in adjuvant therapy trials of HER2+ early breast cancer (EBC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-05.

Identification of Immune-Related Risk Characteristics and Prognostic Value of Immunophenotyping in TNBC.

Background: Triple-negative breast cancer (TNBC) is not sensitive to targeted therapy with HER-2 monoclonal antibody and endocrine therapy due to lack of ER, PR, and HER-2 receptors. TNBC is a breast cancer subtype with the worst prognosis and the highest mortality rate compared with other subtypes. Materials and Methods: Breast cancer-related data were retrieved from The Cancer Genome Atlas (TCGA) database, and 116 cases of triple-negative breast cancer were identified from the data. GSE31519 dataset was retrieved from Gene Expression Omnibus (GEO) database, comprising a total of 68 cases with TNBC. Survival analysis was performed based on immune score, infiltration score and mutation score to explore differences in prognosis of different immune types. Analysis of differentially expressed genes was conducted and GSEA analysis based on these genes was conducted to explore the potential mechanism. Results: The findings showed that comprehensive immune typing is highly effective and accurate in assessing prognosis of TNBC patients. Analysis showed that MMP9, CXCL9, CXCL10, CXCL11 and CD7 are key genes that may affect immune typing of TNBC patients and play an important role in prediction of prognosis in TNBC patients. Conclusion: The current study presents an evaluation system based on immunophenotyping, which provides a more accurate prognostic evaluation tool for TNBC patients. Differentially expressed genes can be targeted to improve treatment of TNBC.

Sortilin-related receptor is a druggable therapeutic target in breast cancer.

In breast cancer, the currently approved anti‐receptor tyrosine‐protein kinase erbB‐2 (HER2) therapies do not fully meet the expected clinical goals due to therapy resistance. Identifying alternative HER2‐related therapeutic targets could offer a means to overcome these resistance mechanisms. We have previously demonstrated that an endosomal sorting protein, sortilin‐related receptor (SorLA), regulates the traffic and signaling of HER2 and HER3, thus promoting resistance to HER2‐targeted therapy in breast cancer. This study aims to assess the feasibility of targeting SorLA using a monoclonal antibody. Our results demonstrate that anti‐SorLA antibody (SorLA ab) alters the resistance of breast cancer cells to HER2 monoclonal antibody trastuzumab in vitro and in ovo. We found that SorLA ab and trastuzumab combination therapy also inhibits tumor cell proliferation and tumor cell density in a mouse xenograft model of HER2‐positive breast cancer. In addition, SorLA ab inhibits the proliferation of breast cancer patient‐derived explant three‐dimensional cultures. These results provide, for the first time, proof of principle that SorLA is a druggable target in breast cancer.

ES30.04 Monoclonal Antibodies Targeting the ErbB Receptors

Blockade of a critical oncogenic target is envisioned as a promising strategy for treating cancer. The blockade of ErbB receptors with anti-ErbB monoclonal antibody represents one such strategy that has been successful in the treatment of HER2-overexpressing multiple solid tumors including NSCLC. Approximately 6% of EGFR mutated NSCLC have EGFR exon 20 insertion (E20Ins) mutations. EGFR E20Ins is the third most common type of EGFR mutation Multiple subtypes and structural differences may limit development of novel targeted therapies. Amivantamab is a fully human EGFR-MET bispecific antibody targeting activating and resistance EGFR mutations and MET mutations and amplifications. Amivantamab demonstrated clinical activity across diverse EGFR mutant NSCLC. In CHRYSALIS phase 1study, amivantamab showed robust efficacy with tolerable safety profile in post-platinum EGFR E20Ins NSCLC. HER 2 mutation occurs in about 2% of lung adenocarcinoma. HER2 mutation is more frequently found in never-smoker, women, Asian, and adenocarcinoma. Contrast to HER2 mutation, HER2 overexpression and amplification is not a definite biomarker to HER2 directed therapy. Anti-HER2 monoclonal antibody as monotherapy or in combination has shown conflicting results in HER2 overexpressed or amplified NSCLC. Compared to EGFR and HER2, HER3 has been somwhat ignored as a therapeutic target most likely due to lack of intrinsc kinase activity. However, upon ligand binding and subsequent dimerization with HER2, HER3 potently activates PI3K pathway and MAPK pathway. HER3 Monoclonal antibody as a monotherapu may not sufficient to fully inhibit tumor cells and combination with other ErbB therapy, chemotherapy may enhance therapeutic effects. Recently, monoclonal antibody targeting HER3 exhibited clinical activity in NRG1 fusion+ NSCLC. In conclusion, rapid pace of targeted drug development transforms lives of NSCLC patients with these rare actionable mutations. ErbB receptor, monoclonal antibody, rare mutation

Cardiovascular Disease Amongst Women Treated for Breast Cancer: Traditional Cytotoxic Chemotherapy, Targeted Therapy, and Radiation Therapy.

Cardiotoxicity can occur acutely during breast cancer treatment and impact the potential for the intended cancer treatment regime to be completed, or as a late effect affecting cancer survivorship. Indeed, the most common cause of mortality in females with early breast cancer is cardiovascular disease, especially in those over the age of 65. Optimal cancer care therefore needs to be delivered without jeopardising cardiovascular health. Understanding the different cardiotoxicities associated with breast cancer treatment is vital to this approach, and therefore, this article seeks to provide an overview of this. Tyrosine kinase inhibitors targeting human epidermal growth factor receptor (HER)-2, immune checkpoint inhibitors (ICI), and cyclin-dependent kinase (CDK) inhibitors are new targeted breast cancer treatments. In particular, ICI are associated with myocarditis that carries a significant mortality, whilst the CDK inhibitor ribociclib causes QT prolongation that requires cardiac surveillance and appropriate dose adjustment to prevent ventricular arrhythmias. The need has always been for strategies to mitigate the risks of cardiovascular toxicities, and new data is promising for the use of dexrazoxane in anthracyclines, and the role of beta blockers and angiotensin converting enzymes inhibitors in anthracyclines and HER-2 monoclonal antibodies such as trastuzumab. Significant headways in breast cancer treatment have resulted in reductions in disease recurrence and mortality, but cardiovascular complications continue to impact the ability to deliver some of these cancer treatments, and the period of cancer survivorship.

Abstract LB-217: Preclinical evaluation of trastuzumab deruxtecan (T-DXd; DS-8201a), a HER2 antibody-drug conjugate, in pediatric solid tumors by the Pediatric Preclinical Testing Consortium (PPTC)

Abstract Introduction: HER2 is expressed in a subset of pediatric solid tumors and is a target of interest for innovative immune therapies including CAR-T cells and antibody-drug conjugates (ADCs). We evaluated preclinical efficacy of T-DXd, a humanized monoclonal HER2 antibody conjugated to a topoisomerase 1 inhibitor payload, DXd, in solid tumor patient derived xenograft (PDX) models. Methods: 7 osteosarcoma (OS), 2 rhabdoid tumor (RT) and 3 Wilms tumor (WT) PDX models with varying HER2 expression were tested using 10 mice per group. ERBB2 mRNA expression was determined using RNA seq. T-DXd or vehicle control was administered IV to mice harboring flank tumors at a dose of 5mg/kg on Day 1. Standard PPTC statistical methods were employed for EFS for treatment (T) and control (C) groups, minimum relative tumor volume (minRTV) and objective response measure. Results: Among PPTC solid tumor models ERBB2 mRNA expression was observed across multiple histologies, with highest expression observed for WT (median = 22 FPKM), followed by RT, OS, and Ewing sarcoma. The relationship between HER2 expression by IHC and by RNAseq was inconsistent. Mice tolerated T-DXd with minimal toxicity. T-DXd significantly prolonged EFS in 5/7 OS, 2/2 RT and 3/3 WT PDX models (see table). Complete response (CR) or maintained CR were observed for 4 of 5 WT and RT models, while stable disease was the best response among OS models. Conclusions: T-DXd exhibits single agent anti-tumor activity in models of pediatric solid tumors. Single mouse testing experiments will be used to extend knowledge of the range of activity of T-DXd for pediatric solid tumors. Correlations between ERBB2 gene expression, HER2 expression by IHC, and genetic changes associated with camptothecin sensitivity are ongoing and will be presented. Clinical trials assessing efficacy of a HER2-directed ADC in pediatric patients with HER2-expressing tumors should be considered. EFS T - C(days)EFS T/C Ratiop-value Gehan-WilcoxonminRTVmean±SDminRTVp-valueObjective Response MeasureOS-120.31.85p < 0.0011.152±0.090p = 0.023PD1OS-230.12.76p < 0.0010.815±0.183p < 0.001PD2OS-94.11.14p = 0.1031.334±0.203p = 1.000PD1OS-1734.01.97p = 0.0091.172±0.179p = 0.017PD1OS-3111.91.84p < 0.0011.676±0.395p = 0.015PD1OS-3361.34.87p < 0.0010.486±0.220p < 0.001SDOS-603.81.11p = 0.0161.084±0.103p = 0.007PD1BT29 (RT)> 58.4> 3.28p < 0.0010.019±0.041p < 0.001MCRRBD2 (RT)> 97.3> 13.57p < 0.0010.021±0.066p < 0.001CRKT-10 (WT)> 85.1> 7.57p < 0.0010.000±0.000p < 0.001MCRKT-11 (WT)18.32.62p < 0.0010.954±0.486p < 0.001PD2KT-13 (WT)> 71.5> 3.69p < 0.0010.019±0.060p < 0.001MCR Citation Format: Pooja Hingorani, Wendong Zhang, Raushan Kurmasheva, Zhongting Zhang, Yifei Wang, Zhaohui Xu, Michael Roth, Jonathan Gill, Douglas Harrison, Stephen Erickson, Edward A. Kolb, Malcolm Smith, Peter Houghton, Richard Gorlick. Preclinical evaluation of trastuzumab deruxtecan (T-DXd; DS-8201a), a HER2 antibody-drug conjugate, in pediatric solid tumors by the Pediatric Preclinical Testing Consortium (PPTC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-217.