Targeting HER2 in breast cancer: new drugs and paradigms on the horizon

Pyrotinib promotes the antitumor effect of T-DM1 by increasing drug endocytosis in HER2-positive breast cancer

Anti-HER2 therapy is integral to the treatment of HER2-positive breast cancer, but drug resistance hampers its effectiveness. Although antibody-drug conjugates (ADCs) are increasingly used in clinical practice, their application is often hindered by adverse reactions and drug resistance. Therefore, it is crucial to enhance the bioavailability of ADCs and reduce their dosages to mitigate both adverse effects and resistance. Pyrotinib's effect on HER2-positive breast cancer cell lines (SK-BR-3 and JIMT-1) was investigated via western blot, focusing on HER2 and downstream pathways. Pyrotinib's influence on HER2 ubiquitination and internalization was assessed through RT-qPCR, western blot, and immunofluorescence. The ability of pyrotinib to augment trastuzumab emtansine (T-DM1) endocytosis and antiproliferative effects was studied via CCK-8 and immunofluorescence. In vivo experiments in nude mice were conducted to explore the therapeutic efficacy of T-DM1 combined with pyrotinib. The single-drug study showed that pyrotinib downregulated HER2 protein levels and HER2 downstream signaling pathways. The mechanism of downregulating HER2 protein levels involved the promotion of HER2 internalization and degradation through the ubiquitin-proteasome pathway. The two-drug combination study showed that pyrotinib promoted the endocytosis of T-DM1, which improved its bioavailability. Increased cellular uptake further enhanced the antitumor effects of T-DM1 in both in vitro and in vivo experiments. Our results reveal the molecular mechanism by which pyrotinib regulates HER2 levels by promoting HER2 internalization, thereby facilitating the endocytosis of T-DM1. These findings suggest a potential combination treatment strategy for the targeted therapy of HER2-positive breast cancer.

Enhancing HER2 testing in breast cancer: predicting fluorescence in situ hybridization (FISH) scores from immunohistochemistry images via deep learning

Breast cancer affects millions globally, necessitating precise biomarker testing for effective treatment. HER2 testing is crucial for guiding therapy, particularly with novel antibody-drug conjugates (ADCs) like trastuzumab deruxtecan, which shows promise for breast cancers with low HER2 expression. Current HER2 testing methods, including immunohistochemistry (IHC) and in situ hybridization (ISH), have limitations. IHC, a semi-quantitative assay, is prone to interobserver variability. While ISH provides higher precision than IHC, it remains more resource-intensive in terms of cost and workflow. However, turnaround time is typically faster than that of other advanced molecular methods such as next-generation sequencing. We adapted the clustering-constrained-attention multiple-instance deep learning model to improve IHC testing and reduce dependence on reflex fluorescence ISH (FISH) tests. Using 5,731 HER2 IHC images, including 592 cases with FISH testing, we trained two models: one for predicting HER2 scores from IHC images and another for predicting FISH scores from equivocal cases. The HER2 IHC score prediction model achieved 91% ± 0.01 overall accuracy and a receiver operating characteristic (ROC) area under the curve (AUC) of 0.98 ± 0.01. The FISH score prediction model had an ROC AUC of 0.84 ± 0.07, with sensitivity at 0.37 ± 0.13 and specificity at 0.96 ± 0.03. External validation on cases from 203 institutions showed similar performance. The HER2 IHC model maintained a 91% ± 0.01 accuracy and an ROC AUC of 0.98 ± 0.01, while the FISH model had an ROC AUC of 0.75 ± 0.03, with sensitivity at 0.28 ± 0.04 and specificity at 0.93 ± 0.01. Our model advances HER2 scoring by reducing subjectivity and variability in current scoring methods. Despite lower accuracy and sensitivity in the FISH prediction model, it may be a beneficial option for settings where reflex FISH testing is unavailable or prohibitive. With high specificity, our model can serve as an effective screening tool, enhancing breast cancer diagnosis and treatment selection.

Exploring Zanidatamab's efficacy across HER2-positive Malignancies: a narrative review

BACKGROUND

HER2-positive cancers involve amplification or overexpression of the HER2 gene, leading to aggressive tumor growth across several cancer types, including breast, gastric, ovarian, and pancreatic cancers. Detection methods such as immunohistochemistry, next-generation sequencing, and fluorescence in situ hybridization are used, with new advancements like biosensors and circulating tumor DNA offering improved diagnostic potential. Treatment strategies have evolved, including anti-HER2 drugs like trastuzumab and newer agents like zanidatamab, which show promise against HER2-positive malignancies.

METHODS

A comprehensive search of the following academic databases was performed including PubMed, Cochrane Library, and clinicaltrials.gov. A detailed search string was made. Studies were selected based on whether they contained the keywords and if they reported the details of treatment for zanidatamab. A total of 16 studies were selected. Abstracts were independently examined by one author and critically reviewed by another and if there were any conflicting viewpoints they were discussed until consensus was reached.

DISCUSSION

Zanidatamab has shown promising clinical outcomes in several HER2-positive cancers, including biliary tract, breast, gastric, and lung cancers, with high disease control rates and progression-free survival. Although it is not yet FDA-approved, it has received priority review for HER2-positive biliary tract cancer, with an FDA decision expected in November 2024. The safety profile of zanidatamab has been well-studied. The most common side effects include diarrhea, infusion reactions, and other mild to moderate treatment-related adverse events. In combination with Palbociclib for HER2-positive breast cancer, more severe side effects were observed, resulting in some patients discontinuing treatment. However, no treatment-related deaths have been reported across trials. While its anticancer efficacy and manageable safety profile are promising, long-term safety and efficacy data are still needed. Early clinical trials demonstrate strong efficacy, though some side effects, such as diarrhea and decreased ejection fraction, were noted. Future research should focus on understanding potential resistance mechanisms and establishing zanidatamab's broader role in the treatment landscape of HER2-positive cancers.

CONCLUSION

In summary, zanidatamab has shown significant tumor response, progression-free survival, disease control, and improved quality of life in early trials, however, the lack of long-term safety and efficacy data remains a key limitation, requiring further research.

Synthesis and biological assessment of chalcone and pyrazoline derivatives as novel inhibitor for ELF3-MED23 interaction

HER2 overexpression significantly contributes to the aggressive nature and recurrent patterns observed in various solid tumors, notably gastric cancers. Trastuzumab, HER2-targeting monoclonal antibody drug, has shown considerable clinical success; however, readily emerging drug resistance emphasizes the pressing need for improved interventions in HER2-overexpressing cancers. To address this, we proposed targeting the protein-protein interaction (PPI) between ELF3 and MED23 as an alternative therapeutic approach to trastuzumab. In this study, we synthesized a total of 26 compounds consisting of 10 chalcones, 7 pyrazoline acetyl, and 9 pyrazoline propionyl derivatives, and evaluated their biological activity as potential ELF3-MED23 PPI inhibitors. Upon systematic analysis, candidate compound 10 was selected due to its potency in downregulating reporter gene activity of ERBB2 promoter confirmed by SEAP activity and its effect on HER2 protein and mRNA levels. Compound 10 effectively disrupted the binding interface between the ELF3 TAD domain and the 391-582 amino acid region of MED23, resulting in successful inhibition of the ELF3-MED23 PPI. This intervention led to a substantial reduction in HER2 levels and its downstream signals in the HER2-positive gastric cancer cell line. Subsequently, compound 10 induced significant apoptosis and anti-proliferative effects, demonstrating superior in vitro and in vivo anticancer activity overall. We found that the anticancer activity of compound 10 was not only restricted to trastuzumab-sensitive cases, but was also valid for trastuzumab-refractory clones. This suggests its potential as a viable therapeutic option for trastuzumab-resistant gastric cancers. In summary, compound 10 could be a novel alternative therapeutic strategy for HER2-overexpressing cancers, overcoming the limitations of trastuzumab.

Updates in Treatment of HER2-positive Metastatic Breast Cancer

OPINION STATEMENT

The therapeutic landscape for HER2-positive metastatic breast cancer has exploded in the last two decades following the initial advent of trastuzumab, a monoclonal antibody. While the first line treatment has remained a combination of dual HER2 blockade with taxane chemotherapy, we now have several exciting options in the second line and beyond. The introduction of antibody-drug conjugates, in specific trastuzumab deruxtecan, has resulted in the best progression-free survival among patients with this subtype of breast cancer. Given the excellent outcomes of these drugs, clinical trials are now evaluating the role of ADCs in the front-line setting in previously untreated patients. In addition, there are also clinical trials evaluating the role of other targets in patients with HER2-positive cancers, including PI3KCA mutations, PD-L1 and CDK4/6. Given the predilection for brain metastases in this population, there is enthusiasm to identify the optimal combination of effective treatments. Tucatinib, capecitabine, and trastuzumab combination represent one such promising strategy. With the increasing longevity of these patients, important clinical questions include optimal treatment sequencing, the role of de-escalation of treatment in excellent responders, and the associated financial toxicity. Despite the aggressive nature of this subtype of breast cancer, the outcomes continue to improve for these patients with the evolving treatments.

Loss of chromosome cytoband 13q14.2 orchestrates breast cancer pathogenesis and drug response

Breast cancer (BCa) is a major global health challenge. The BCa genome often carries extensive somatic copy number alterations (CNAs), including gains/amplifications and losses/deletions. These CNAs significantly affect tumor development, drug response and patient survival. However, how individual CNAs contribute is mostly elusive. We identified loss of chromosome 13q14.2 as a key CNA in BCa, occurring in up to 63% of patients, depending on the subtype, and correlating with poor survival. Through multi-omics and in vitro analyses, we uncover a paradoxical role of 13q14.2 loss, promoting both cell cycle and pro-apoptotic pathways in cancer cells, while also associating with increased NK cell and macrophage populations in the tumor microenvironment. Notably, 13q14.2 loss increases BCa susceptibility to BCL2 inhibitors, both in vitro and in patient-derived xenografts. Thus, 13q14.2 loss could serve as a biomarker for BCa prognosis and treatment, potentially improving outcomes for BCa patients.

Personalized treatment approach for HER2-positive metastatic breast cancer

Breast cancer (BC) is a leading global concern for women, with 30% being HER2-positive cases linked to poorer outcomes. Targeted therapies like trastuzumab deruxtecan (T-DXd), trastuzumab, pertuzumab, and T-DM1 have revolutionized HER2-positive metastatic breast cancer (MBC) treatment. Although these therapies have improved MBC management and patient outcomes, resistance can develop, reducing effectiveness. Personalized strategies based on tumor characteristics offer hope for better responses and longer outcomes. This review outlines insights into MBC patients responding well to anti-HER2 treatments, even across multiple treatment regimen. Recent immunotherapy, locoregional therapy, and liquid biopsy breakthroughs are covered, suggesting ways to increase long-term responders. Personalized approaches have boosted HER2-positive MBC outcomes, and ongoing research is crucial to uncover new treatments and biomarkers, potentially elevating long-term response rates and prognoses. This may aid in providing new direction to breast cancer clinics.

HER2-targeted therapies for HER2-positive early-stage breast cancer: present and future

Breast cancer (BC) has the second highest incidence among cancers and is the leading cause of death among women worldwide. The human epidermal growth factor receptor 2 (HER2) is overexpressed in approximately 20%-30% of BC patients. The development of HER2-targeted drugs, including monoclonal antibodies (mAbs), tyrosine kinase inhibitors (TKIs) and antibody-drug conjugates (ADCs), has improved the operation rate and pathological remission rate and reduced the risk of postoperative recurrence for HER2-positive early-stage BC (HER2+ EBC) patients. This review systematically summarizes the mechanisms, resistance, therapeutic modalities and safety of HER2-targeted drugs and helps us further understand these drugs and their use in clinical practice for patients with HER2+ EBC.

Polypharmacology: promises and new drugs in 2022

Polypharmacology is an emerging strategy of design, synthesis, and clinical implementation of pharmaceutical agents that act on multiple targets simultaneously. It should not be mixed up with polytherapy, which is based on the use of multiple selective drugs and is considered a cornerstone of current clinical practice. However, this 'classic' approach, when facing urgent medical challenges, such as multifactorial diseases, increasing resistance to pharmacotherapy, and multimorbidity, seems to be insufficient. The 'novel' polypharmacology concept leads to a more predictable pharmacokinetic profile of multi-target-directed ligands (MTDLs), giving a chance to avoid drug-drug interactions and improve patient compliance due to the simplification of dosing regimens. Plenty of recently marketed drugs interact with multiple biological targets or disease pathways. Many offer a significant additional benefit compared to the standard treatment regimens. In this paper, we will briefly outline the genesis of polypharmacology and its differences to polytherapy. We will also present leading concepts for obtaining MTDLs. Subsequently, we will describe some successfully marketed drugs, the mechanisms of action of which are based on the interaction with multiple targets. To get an idea, of whether MTDLs are indeed important in contemporary pharmacology, we also carefully analyzed drugs approved in 2022 in Germany: 10 out of them were found multi-targeting, including 7 antitumor agents, 1 antidepressant, 1 hypnotic, and 1 drug indicated for eye disease.

Cross-Resistance Among Sequential Cancer Therapeutics: An Emerging Issue

Over the past two decades, cancer treatment has benefited from having a significant increase in the number of targeted drugs approved by the United States Food and Drug Administration. With the introduction of targeted therapy, a great shift towards a new era has taken place that is characterized by reduced cytotoxicity and improved clinical outcomes compared to traditional chemotherapeutic drugs. At present, targeted therapies and other systemic anti-cancer therapies available (immunotherapy, cytotoxic, endocrine therapies and others) are used alone or in combination in different settings (neoadjuvant, adjuvant, and metastatic). As a result, it is not uncommon for patients affected by an advanced malignancy to receive subsequent anti-cancer therapies. In this challenging complexity of cancer treatment, the clinical pathways of real-life patients are often not as direct as predicted by standard guidelines and clinical trials, and cross-resistance among sequential anti-cancer therapies represents an emerging issue. In this review, we summarize the main cross-resistance events described in the diverse tumor types and provide insight into the molecular mechanisms involved in this process. We also discuss the current challenges and provide perspectives for the research and development of strategies to overcome cross-resistance and proceed towards a personalized approach.