Aiming at a Tailored Cure for ERBB2-Positive Metastatic Breast Cancer: A Review

Dual HER2 inhibition: mechanisms of synergy, patient selection, and resistance

HER2-targeted therapies for patients with HER2+ breast cancer are rapidly evolving, offering a range of more complex and personalized treatment options. Currently, an array of anti-HER2 monoclonal antibodies, tyrosine kinase inhibitors and antibody-drug conjugates are administered, sometimes alongside chemotherapy or endocrine therapy, both in curative and palliative contexts. However, the heterogeneous nature of HER2+ breast cancer demands a deeper understanding of disease biology and its role in responsiveness to novel HER2-targeted agents, as well as non-HER2-targeted therapies, in order to optimize patient outcomes. In this Review, we revisit the mechanisms of action of HER2-targeted agents, examine the evidence supporting the use of dual HER2 blockade in patients with HER2-amplified tumours, and explore the role of biomarkers in guiding future treatment strategies. We also discuss potential implications for the future treatment of patients with HER2+ breast cancer.

Inetetamab-based therapy in real-world treatment patterns with HER2-positive advanced breast cancer patients: a retrospective single-center study

Background

Inetetamab is a novel antibody targeting human epidermal growth factor receptor 2 (HER2) developed in China. Due to its optimized antibody-dependent cell-mediated cytotoxicity effect compared with trastuzumab, it has shown good efficacy and safety in the treatment of HER2-positive advanced breast cancer (ABC).

Objectives

This study aimed to investigate the efficacy and safety of inetetamab combination therapy in the treatment of HER2-positive ABC in real-world clinical practice.

Design

Retrospective study.

Methods

A total of 133 patients with HER2-positive ABC who were treated with inetetamab-based regimens between March 2020 and January 2024 were retrospectively included in this study. The main endpoint was median progression-free survival (mPFS). The secondary endpoints included objective response rate (ORR), disease control rate (DCR), and safety.

Results

The study included 133 HER2-positive ABC patients, and the median age was 55 years. The mPFS was 8.0 (6.7-9.3) months. The ORR was 50.4%, while the DCR was 88.7%. The mPFS for patients receiving inetetamab-based therapy as first to second, third to fourth, and later lines of metastatic treatment were 14.0, 7.0, and 6.0 months, respectively. Patients treated with inetetamab plus pyrotinib plus chemotherapy, especially with capecitabine, had the best outcomes (mPFS = 14.0 months). Multivariate analysis revealed that prior HER2-TKI treatment was significantly associated with worse PFS (hazard ratios 2.829, 95% confidence interval 1.265-6.328, p = 0.011). Subgroup analysis indicated that patients without visceral metastases had significantly better PFS (14.0 months vs 8.0 months, p = 0.003). The overall incidence of any grade adverse events (AEs) was 100%, with most being grades 1-2. Severe complications included neutropenia (37.6%) and leukopenia (33.1%).

Conclusions

Inetetamab-based combination therapy shows promising efficacy and good safety in patients with HER2-positive ABC. It is one of the late-line treatment options for Chinese patients with HER2-positive ABC.

Palliative surgery versus non-surgery of the solitary metastatic lesion in De novo metastatic breast cancer: A SEER based study

This study aimed to evaluate whether palliative surgery for metastatic lesion could provide a survival benefit in metastatic breast cancer (MBC) patients with solitary metastasis. De novo MBC patients with solitary distant lesions were enrolled utilizing the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) was conducted to form matched pairs of the surgery group and the non-surgery group. The breast cancer-specific survival (BCSS) and overall survival (OS) outcomes between the 2 groups were compared in the following 3 sample models: the entire cohort of MBC (7665 cases); subgroups of patients with different isolated metastatic organs; and subgroups of patients with different molecular subtypes for each isolated metastatic organ. Compared with the Non-surgery group, the surgery group showed better BCSS and OS before PSM (HR = 0.88, 95% CI = 0.79-0.99, P = .04 and HR = 0.85, 95% CI = 0.76-0.95, P = .006, respectively). After PSM, palliative surgery still provided an OS benefit in patients with brain metastasis and lung metastasis (HR = 0.59, 95% CI = 0.37-0.95, P = .01 and HR = 0.64, 95% CI = 0.45-0.90, P = .02, respectively). Likewise, a better BCSS benefit was also found in the subset of patients with brain metastasis (HR = 0.61, 95% CI = 0.38-1.00, P = .01). Further stratification analysis indicated that patients with the luminal A subtype with brain metastasis have a better BCSS (HR = 0.36, 95% CI = 0.16-0.79, P = .04) and OS (HR = 0.37, 95% CI = 0.18-0.75, P = .03) after undergoing palliative surgery than nonsurgical treatment. Our study originality showed that palliative surgery for metastatic lesion could improve survival prognosis in patients with special single-organ metastasis and specific molecular subtypes. More clinical studies are needed to determine whether palliative surgery should be performed in MBC patients.

Combined SERS-Raman screening of HER2-overexpressing or silenced breast cancer cell lines

BACKGROUND

Breast cancer (BC) is a heterogeneous neoplasm characterized by several subtypes. One of the most aggressive with high metastasis rates presents overexpression of the human epidermal growth factor receptor 2 (HER2). A quantitative evaluation of HER2 levels is essential for a correct diagnosis, selection of the most appropriate therapeutic strategy and monitoring the response to therapy.

RESULTS

In this paper, we propose the synergistic use of SERS and Raman technologies for the identification of HER2 expressing cells and its accurate assessment. To this end, we selected SKBR3 and MDA-MB-468 breast cancer cell lines, which have the highest and lowest HER2 expression, respectively, and MCF10A, a non-tumorigenic cell line from normal breast epithelium for comparison. The combined approach provides a quantitative estimate of HER2 expression and visualization of its distribution on the membrane at single cell level, clearly identifying cancer cells. Moreover, it provides a more comprehensive picture of the investigated cells disclosing a metabolic signature represented by an elevated content of proteins and aromatic amino acids. We further support these data by silencing the HER2 gene in SKBR3 cells, using the RNA interference technology, generating stable clones further analysed with the same combined methodology. Significant changes in HER2 expression are detected at single cell level before and after HER2 silencing and the HER2 status correlates with variations of fatty acids and downstream signalling molecule contents in the context of the general metabolic rewiring occurring in cancer cells. Specifically, HER2 silencing does reduce the growth ability but not the lipid metabolism that, instead, increases, suggesting that higher fatty acids biosynthesis and metabolism can occur independently of the proliferating potential tied to HER2 overexpression.

CONCLUSIONS

Our results clearly demonstrate the efficacy of the combined SERS and Raman approach to definitely pose a correct diagnosis, further supported by the data obtained by the HER2 gene silencing. Furthermore, they pave the way to a new approach to monitor the efficacy of pharmacologic treatments with the aim to tailor personalized therapies and optimize patients' outcome.

Comparison of the prognostic effect of pyrotinib plus trastuzumab and chemotherapy different lines therapy in HER2-positive advanced breast cancer

This study aimed to compare the efficacy of pyrotinib, trastuzumab combined with chemotherapy with different lines therapy in human epidermal growth factor receptor 2- (HER2-) positive advanced breast cancer (ABC) and analyze the factors affecting the prognosis. A total of 84 patients with median age of 49 year-old. The mPFS of patients receiving first-line pyrotinib plus trastuzumab and chemotherapy was the longest (11 months) compared with second- and third line patients (p = 0.106). The objective response rate (ORR) and disease control rate (DCR) of the total population were 33.3% and 82.1% respectively. Subgroup analysis suggested that using pyrotinib plus trastuzumab and Albumin-bound paclitaxel was not inferior to combine with Vinorelbine in regards of PFS. Histological grade (OR: 0.233[0.069 ∼ 0.781], p = 0.018) and tumor location (OR: 0.286[0.087 ∼ 0.942], p = 0.040) were independent factors influencing the ORR. Multivariate cox analysis showed that Ki-67 was independently associated with increased risk of progression (HR: 1.843[1.044-3.254], p = 0.035). The most common adverse events were diarrhea (17.9%) and neutropenia (11.9%). In the first-, second- and third-line treatment, pyrotinib plus trastuzumab and chemotherapy is effective and safe. Pyrotinib and trastuzumab combined with Albumin-bound paclitaxel may be a potential ideal treatment plan for HER2-positive advanced breast cancer.

Real-world impact of dual anti-HER2 antibodies on cardiac function in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer

•101 patients with HER2+ MBC on pertuzumab and trastuzumab were included. •Most observed cardiotoxicity were mild, all occurred early within 24 months. •Presence of cardiovascular co-morbidities predicts treatment cardiotoxicity. •Risk-stratified de-escalation of long-term cardiac surveillance should be discussed.

Inetetamab combined with pyrotinib and oral vinorelbine for patients with human epidermal growth factor receptor 2 positive advanced breast cancer: A single-arm phase 2 clinical trial

Background

Human epidermal growth factor receptor 2 (HER2)-targeted agents have significantly improved the outcomes of patients with HER2-positive breast cancer; however, a large proportion of patients still develop resistance to trastuzumab. In this study, we investigated the efficacy and safety of inetetamab, another anti-HER2 antibody, combined with pyrotinib and oral vinorelbine in patients with HER2-positive advanced breast cancer so as to provide new ideas for the treatment.

Methods

In this prospective, single-arm, phase 2 trial, patients with HER2-positive advanced breast cancer with disease progression after trastuzumab were recruited. Patients received a combination of inetetamab (loading dose of 8 mg/kg and subsequent doses of 6 mg/kg intravenously once every 3 weeks), pyrotinib (400 mg orally once daily), and vinorelbine (60 mg/m2 orally once weekly) until disease progression or intolerable toxicity. The primary endpoint was progression-free survival (PFS). The secondary endpoints included objective response rate (ORR), overall survival (OS), disease control rate (DCR), and safety.

Results

Between February 13, 2022 and December 25, 2022, 30 patients were screened and enrolled in this study. The median age of the patients at enrollment was 54 years, 12 patients (40.0 %) had hormone-receptor-positive disease and 23 patients (76.7 %) had visceral metastasis. The median PFS was 8.63 months (95 % confidence interval [CI] 4.15-13.12 months). The median OS was not reached. The ORR was 53.3 % (16/30) and the DCR was 96.7 % (29/30). The most common Grade III/IV adverse events were leukopenia (n = 5, 16.7 %), neutropenia (n = 4, 13.3 %), and diarrhea (n = 3, 10 %). No treatment-related serious adverse events or deaths occurred.

Conclusions

The combination regimen of inetetamab, pyrotinib, and oral vinorelbine showed encouraging efficacy and favorable safety in patients with HER2-positive advanced breast cancer and could be considered as an alternative treatment option for the patients.

Trial registration

No.NCT05823623; https://www.clinicaltrials.gov/.

Multiomics of HER2-low triple-negative breast cancer identifies a receptor tyrosine kinase-relevant subgroup with therapeutic prospects

To provide complementary information and reveal the molecular characteristics and therapeutic insights of HER2-low breast cancer, we performed this multiomics study of hormone receptor-negative (HR-) and HER2-low breast cancer, also known as HER2-low triple-negative breast cancer (TNBC), and identified 3 subgroups: basal-like, receptor tyrosine kinase-relevant (TKR), and mesenchymal stem-like. These 3 subgroups had distinct features and potential therapeutic targets and were validated in external data sets. Interestingly, the TKR subgroup (which exists in both HR+ and HR- breast cancer) had activated HER2 and downstream MAPK signaling. In vitro and in vivo patient-derived xenograft experiments revealed that pretreatment of the TKR subgroup with a tyrosine kinase inhibitor (lapatinib or tucatinib) could inhibit HER2 signaling and induce accumulated expression of nonfunctional HER2, resulting in increased sensitivity to the sequential HER2-targeting, Ab-drug conjugate DS-8201. Our findings identify clinically relevant subgroups and provide potential therapeutic strategies for HER2-low TNBC subtypes.

Advances in Early Breast Cancer Risk Profiling: From Histopathology to Molecular Technologies

Early breast cancer (BC) is the definition applied to breast-confined tumors with or without limited involvement of locoregional lymph nodes. While risk stratification is essential for guiding clinical decisions, it can be a complex endeavor in these patients due to the absence of comprehensive guidelines. Histopathological analysis and biomarker assessment play a pivotal role in defining patient outcomes. Traditional histological criteria such as tumor size, lymph node involvement, histological type and grade, lymphovascular invasion, and immune cell infiltration are significant prognostic indicators. In addition to the hormone receptor, HER2, and-in specific scenarios-BRCA1/2 testing, molecular subtyping through gene expression profiling provides valuable insights to tailor clinical decision-making. The emergence of "omics" technologies, applicable to both tissue and liquid biopsy samples, has broadened our arsenal for evaluating the risk of early BC. However, a pressing need remains for standardized methodologies and integrated pathological models that encompass multiple analytical dimensions. In this study, we provide a detailed examination of the existing strategies for early BC risk stratification, intending to serve as a practical guide for histopathologists and molecular pathologists.

B-cells and regulatory T-cells in the microenvironment of HER2+ breast cancer are associated with decreased survival: a real-world analysis of women with HER2+ metastatic breast cancer

BACKGROUND

Despite major improvements in treatment of HER2-positive metastatic breast cancer (MBC), only few patients achieve complete remission and remain progression free for a prolonged time. The tumor immune microenvironment plays an important role in the response to treatment in HER2-positive breast cancer and could contain valuable prognostic information. Detailed information on the cancer-immune cell interactions in HER2-positive MBC is however still lacking. By characterizing the tumor immune microenvironment in patients with HER2-positive MBC, we aimed to get a better understanding why overall survival (OS) differs so widely and which alternative treatment approaches may improve outcome.

METHODS

We included all patients with HER2-positive MBC who were treated with trastuzumab-based palliative therapy in the Netherlands Cancer Institute between 2000 and 2014 and for whom pre-treatment tissue from the primary tumor or from metastases was available. Infiltrating immune cells and their spatial relationships to one another and to tumor cells were characterized by immunohistochemistry and multiplex immunofluorescence. We also evaluated immune signatures and other key pathways using next-generation RNA-sequencing data. With nine years median follow-up from initial diagnosis of MBC, we investigated the association between tumor and immune characteristics and outcome.

RESULTS

A total of 124 patients with 147 samples were included and evaluated. The different technologies showed high correlations between each other. T-cells were less prevalent in metastases compared to primary tumors, whereas B-cells and regulatory T-cells (Tregs) were comparable between primary tumors and metastases. Stromal tumor-infiltrating lymphocytes in general were not associated with OS. The infiltration of B-cells and Tregs in the primary tumor was associated with unfavorable OS. Four signatures classifying the extracellular matrix of primary tumors showed differential survival in the population as a whole.

CONCLUSIONS

In a real-world cohort of 124 patients with HER2-positive MBC, B-cells, and Tregs in primary tumors are associated with unfavorable survival. With this paper, we provide a comprehensive insight in the tumor immune microenvironment that could guide further research into development of novel immunomodulatory strategies.

Low interobserver agreement among subspecialised breast pathologists in evaluating HER2-low breast cancer

AIMS

Metastatic HER2-low breast cancer (HLBC) can be treated by trastuzumab deruxtecan. Assessment of low levels of HER2 protein expression suffers from poor interobserver reproducibility. The aim of the study was to evaluate the interobserver agreement among subspecialised breast pathologists and develop a practical algorithm for assessing HLBC.

METHODS

Six breast pathologists (4 juniors, 2 seniors) evaluated 106 HER2 immunostained slides with 0/1+expression. Two rounds (R1, R2) of ring study were performed before and after training with a modified Ki-67 algorithm, and concordance was assessed.

RESULTS

Agreement with 5% increments increased from substantial to almost perfect (R1: 0.796, R2: 0.804), and remained substantial for three categories (<1% vs 1%-10% vs >10%) (R1: 0.768, R2: 0.764). Seniors and juniors had almost perfect agreement with 5% increments (R1: 0.859 and 0.821, R2: 0.872 and 0.813). For the three categories, agreement remained almost perfect among seniors (R1: 0.837, R2: 0.860) and substantial among juniors (R1: 0.792, R2: 0.768). Binary analysis showed suboptimal agreement, decreasing for both juniors and seniors from substantial (R1: 0.650 and 0.620) to moderate (R2: 0.560 and 0.554) using the 1% cut-off, and increasing from moderate to substantial (R1: 0.478, R2: 0.712) among seniors but remaining moderate (R1: 0.576, R2: 0.465) among juniors using the 10% cut-off. The average scoring time per case was higher (72 vs 92 s).

CONCLUSIONS

Subspecialised breast pathologists have suboptimal agreement for immunohistochemical evaluation of HLBC using the modified Ki-67 methodology. An urgent need remains for a new assay/algorithm to reliably evaluate HLBC.

A new paradigm for classifying and treating HER2-positive breast cancer

BACKGROUND

Because of the phenomenal success of treatment with monoclonal antibodies and antibody-drug conjugates targeting human epidermal growth factor receptor 2 (HER2), most patients with early-stage HER2-positive breast cancer (HER2+ BC) and some with limited metastatic diseases have been cured, and those who have not been cured have achieved significant improvements in overall survival, which has weakened the role of the TNM staging system in the prognosis of HER2+ BC today. Given that the disease is now highly curable, treatment conception, classification, and modalities should differ from those of cancer types with a poor prognosis. It is warranted to build a new paradigm for classifying and treating HER2+ BC.

RECENT FINDINGS

In our personal view, we suggest that the classification system should be based not only on traditional anatomy and cancer biology but also on available treatment regimens, their exceptional outcomes, and their toxicities. In this regard, we developed a new concise classification of HER2+ BC based on the TNM staging system, a review of the literature, research results, and our clinical experience, dividing the patients into four distinct groups: curable (lymph-node negative and small (≤3 cm) early breast cancer), do our best to cure (locally advanced or tumors >3 cm early breast cancer), hope for cure (local-regional recurrent, limited metastases, and exceptional responders), and incurable (metastatic breast cancer with poor performance status or non-exceptional responders).

CONCLUSION

It will assist clinicians in developing an optimal treatment regimen at the outset, curing more HER2+ BC patients and improving their quality of life.

Optimizing the safety of antibody-drug conjugates for patients with solid tumours

Over the past 5 years, improvements in the design of antibody-drug conjugates (ADCs) have enabled major advances that have reshaped the treatment of several advanced-stage solid tumours. Considering the intended rationale behind the design of ADCs, which is to achieve targeted delivery of cytotoxic molecules by linking them to antibodies targeting tumour-specific antigens, ADCs would be expected to be less toxic than conventional chemotherapy. However, most ADCs are still burdened by off-target toxicities that resemble those of the cytotoxic payload as well as on-target toxicities and other poorly understood and potentially life-threatening adverse effects. Given the rapid expansion in the clinical indications of ADCs, including use in curative settings and various combinations, extensive efforts are ongoing to improve their safety. Approaches currently being pursued include clinical trials optimizing the dose and treatment schedule, modifications of each ADC component, identification of predictive biomarkers for toxicities, and the development of innovative diagnostic tools. In this Review, we describe the determinants of the toxicities of ADCs in patients with solid tumours, highlighting key strategies that are expected to improve tolerability and enable improvements in the treatment outcomes of patients with advanced-stage and those with early stage cancers in the years to come.

Targeting Post-Translational Modifications to Improve Combinatorial Therapies in Breast Cancer: The Role of Fucosylation

Various tumors rely on post-translational modifications (PTMs) to promote invasiveness and angiogenesis and to reprogram cellular energetics to abate anti-cancer immunity. Among PTMs, fucosylation is a particular type of glycosylation that has been linked to different aspects of immune and hormonal physiological functions as well as hijacked by many types of tumors. Multiple tumors, including breast cancer, have been linked to dismal prognoses and increased metastatic potential due to fucosylation of the glycan core, namely core-fucosylation. Pre-clinical studies have examined the molecular mechanisms regulating core-fucosylation in breast cancer models, its negative prognostic value across multiple disease stages, and the activity of in vivo pharmacological inhibition, instructing combinatorial therapies and translation into clinical practice. Throughout this review, we describe the role of fucosylation in solid tumors, with a particular focus on breast cancer, as well as physiologic conditions on the immune system and hormones, providing a view into its potential as a biomarker for predicating or predicting cancer outcomes, as well as a potential clinical actionability as a biomarker.

A comprehensive prognostic and immune infiltration analysis of EXOC3L1 in pan-cancer

Exocyst complex component 3 like 1 (EXOC3L1) is widely present in various human tissues, which mainly regulates insulin secretion. However, its roles in tumors remain unclear. In the present study, we aimed to investigate the roles of EXOC3L1 in pan-cancer, and the data was downloaded from of the University of California Santa Cruz (UCSC) Xena and the Cancer Genome Atlas (TCGA). The expression status of EXOC3L1 was studied in the TCGA_GTEx samples, TCGA samples and paired samples in TCGA, respectively. Subsequently, Kaplan-Meier analysis was applied to 33 kinds of tumors in TCGA, among the cancers that EXOC3L1 can affect prognosis, clinical correlation analysis and univariate Cox regression analysis were performed. Furthermore, representative cancers kidney renal clear cell carcinoma (KIRC) and lung squamous cell carcinoma (LUSC) with a sample size larger than 500 were selected to construct nomogram models to confirm the prognostic value of EXOC3L1 in cancers. Additionally, the associations of EXOC3L1 with immune cell infiltrations were performed as well. Mechanistically, functional enrichment analysis was performed to explore potential signaling pathways that EXOC3L1 may involve in. Our study found that EXOC3L1 was differentially expressed in a variety of tumors and was associated with the clinical outcomes and immune microenvironment of several tumors, it may affect the occurrence and development of tumors through NOTCH signaling pathway, PI3K-AKT signaling pathway and immune-related pathways. In conclusion, we propose that EXOC3L1 may serve as a potential prognostic biomarker and a promising target for cancer immunotherapy in a variety of cancers.

Trastuzumab therapy duration in HER2-positive de novo metastatic breast cancer: 1999-2018

PURPOSE

The optimal duration of first-line trastuzumab (T) treatment for de novo stage IV HER2-positive metastatic breast cancer (MBC) patients after complete response (CR) is not known.

METHODS

A retrospective cohort study of de novo stage IV HER2-positive MBC patients who had trastuzumab included in their initial treatment (n = 69), 1999-2018, was conducted with follow-up for CR, progressive disease (PD), vital status, and disease-specific survival (DSS). Statistics included Kaplan-Meier plots and Cox proportional hazards models.

RESULTS

Mean trastuzumab treatment time was 4.1 years (range 0.1-15). 54% of patients experienced CR at average time 9 months on treatment (n = 37). Eight CR patients discontinued T treatment after 18 months average post-CR time (range 0-86) and twenty-nine stayed on T treatment post CR [average 65 months (range 10-170)]. Average follow-up was 6 years, range 1-15 years. 5-year DSS was 92% for CR on T patients (N = 29); 88% CR off T (n = 8); 73% No CR on T (n = 14); and 29% No CR off T (n = 18) (p < 0.001). In forward Cox proportional hazards modeling, CR = yes [HzR = 0.31, (95% CI 0.14, 0.73), p = 0.007], continuous T treatment > 2 years [HzR = 0.24, (95% CI 0.10, 0.62), p = 0.003], and age < 65 [HzR = 0.29, (95% CI 0.11, 0.81), p = 0.018] were significantly associated with better DSS.

CONCLUSION

Maximum trastuzumab treatment time to CR was 27 months with 2 or more years trastuzumab treatment independently associated with better survival. Survival comparisons and hazard modeling both indicate as good or better survival associated with continuous trastuzumab treatment regardless of CR status. Word count (n = 250).

Improving HER2 testing reproducibility in HER2-low breast cancer

HER2 is a pillar biomarker in breast cancer, and it is assessed by immunohistochemistry (IHC) using a three-tier scoring system and reflex in situ hybridization (ISH) for IHC score 2+. Novel HER2-directed antibody-drug conjugates have demonstrated significant antitumor activity in breast cancers with low levels of HER2 expression, i.e. IHC score 1+ or ISH-negative IHC score 2+. Both primary and acquired resistance to anti-HER2 therapies remains a challenge in the treatment of breast cancers according to the HER2 positivity continuum. Thus, the ability to precisely discriminate among HER2-zero, HER2-low, and HER2-positive breast cancers is no longer a mere academic exercise. HER2 testing criteria, guidelines, and quality controls are re-gaining momentum for this new clinical need. Therefore, all preanalytical and analytical variables that might trouble the sensitivity and reproducibility of this test should be carefully considered to address all possible issues and open all possible therapeutic opportunities for breast cancer patients.