Trastuzumab treatment after progression in HER2-positive metastatic breast cancer following relapse of trastuzumab-based regimens: a meta-analysis

A real-world study of treatment sequences and second-line clinical outcomes in patients with HER2-positive metastatic breast cancer in US community practice

PURPOSE

Standard-of-care for HER2-positive metastatic breast cancer (HER2 + mBC) patients consists of trastuzumab ± pertuzumab with chemotherapy in first-line (1L), and ado-trastuzumab emtansine (T-DM1) or the more recently approved trastuzumab deruxtecan (T-DXd) in second-line (2L). Contemporary data on treatment sequencing and real-world effectiveness is limited. This study aims to report 2L treatments and outcomes among HER2 + mBC patients in the United States (US).

METHODS

HER2 + mBC patients initiating 2L treatment (index date) between January 2014 and February 2021 were identified from the Syapse Learning Health Network (LHN) database. Summary statistics for patient characteristics, treatment received, reasons for 2L discontinuation and time to 2L-clinical outcomes are reported.

RESULTS

Of the 312 patients initiating 2L treatment, had a median age of 59 years (interquartile range [IQR], 50-66) at the start of 2L. The majority were white (69%) and had de novo mBC (62%). Top three 2L regimens included T-DM1 ± endocrine therapy (29%), trastuzumab/pertuzumab/taxane (10%) and T-DM1/trastuzumab (8%). Around 88% discontinued 2L and 63% received subsequent treatment. Median time-to-next-treatment was 10.6 months (95% CI, 8.8-13.3) and real-world progression-free-survival was 7.9 months (95% CI, 7.0-9.9). Among 274 patients who discontinued 2L, 47% discontinued due to progression and 17% because of intolerance/toxicity, respectively.

CONCLUSION

This real-world US study showed that approximately two-thirds of 2L patients received subsequent therapy and disease progression was the most common reason for 2L discontinuation highlighting the need for timely 2L treatment with the most efficacious drug to allow patients to achieve longer treatment duration and delayed progression.

Anti-HER2 Drugs for the Treatment of Advanced HER2 Positive Breast Cancer

OPINION STATEMENT

Approximately 15-20% of breast cancers (BC) demonstrate HER2 overexpression/gene amplification. Historically, before the era of HER2-directed therapies, this subtype was associated with poor prognosis. Anti-HER2 agents dramatically changed the natural course of disease and significantly prolonged patients' survival. In recent years, a number of new anti-HER2 therapies have been developed, and their approvals offer new therapeutic options for patients with advanced HER2-positive breast cancer. At present, HER2 pathway blocking drugs used in the treatment of metastatic breast cancer worldwide include trastuzumab and pertuzumab in the first-line treatment; trastuzumab deruxtecan and trastuzumab emtansine in the second line; and tucatinib, neratinib, lapatinib, and margetuximab in further lines of treatment of advanced HER2 positive breast cancer. Additionally, there are many clinical trials underway evaluating drugs blocking the HER2 pathway in advanced disease setting. This article presents new treatment options, discussing the most important findings from clinical trials and real-world reports, clinical benefits and risks of treatment, as well as efficacy of re-treatment with trastuzumab in metastatic breast cancer. New data challenge the current standards, and a number of questions arise regarding the optimal sequence of anti-HER2 targeted therapies, the optimal combination, including endocrine agents in luminal HER2 positive tumors and treatment of special patient population such as patients with brain metastases (BM).

Efficacy and safety of inetetamab-containing regimens in patients with HER2-positive metastatic breast cancer: a real-world retrospective study in China

Background

Inetetamab (cipterbin) is an innovative anti-HER2 humanized monoclonal antibody. The efficacy and safety of a combination of inetetamab and vinorelbine in the first-line treatment of human epidermal receptor positive (HER2+) metastatic breast cancer (MBC) have been confirmed. We aimed to investigate real-world data of inetetamab in complex clinical practice.

Methods

We retrospectively reviewed the medical records of patients who received inetetamab as a salvage treatment at any line setting from July 2020 to June 2022. The main endpoint was progression-free survival (PFS).

Results

A total of 64 patients were included in this analysis. The median progression-free survival (mPFS) was 5.6 (4.6-6.6) months. Of the patients, 62.5% received two or more lines of therapy before treatment with inetetamab. The most common chemotherapy and anti-HER2 regimens combined with inetetamab were vinorelbine (60.9%) and pyrotinib (62.5%), respectively. Patients treated with inetetamab plus pyrotinib plus vinorelbine benefited the most (p=0.048), with the mPFS of 9.3 (3.1-15.5) months and an objective response rate of 35.5%. For patients with pyrotinib pretreatment, inetetamab plus vinorelbine plus pyrotinib agents resulted in mPFS of 10.3 (5.2-15.4) months. Regimens (inetetamab plus vinorelbine plus pyrotinib vs. other therapeutic agents) and visceral metastases (yes vs. no) were independent predictors of PFS. Patients with visceral metastases treated with inetetamab plus vinorelbine plus pyrotinib had a mPFS of 6.1(5.1-7.1) months. The toxicity of inetetamab was tolerable, with the most common grade 3/4 adverse event being leukopenia (4.7%).

Conclusions

HER2+ MBC patients pretreated with multiple-line therapies still respond to inetetamab-based treatment. Inetetamab combined with vinorelbine and pyrotinib may be the most effective treatment regimen, with a controllable and tolerable safety profile.

Trastuzumab-based regimens beyond progression: A crucial treatment option for HER2+ advanced/metastatic breast cancer

Upon its establishment for the treatment of metastatic breast cancer (mBC), continuing trastuzumab beyond disease progression was an important paradigm shift that became the recommendation by major guidelines. However, data supporting continuation of human epidermal growth factor receptor 2 (HER2) blockade with trastuzumab beyond the second-line setting are limited, resulting in a lack of approval of, or access to, this therapeutic strategy in many countries. This study aimed to provide additional data on the continued use of trastuzumab and trastuzumab-based therapies in combination with chemotherapy (CT) as third-line treatment for patients with mBC. This open-cohort, retrospective, observational study used deidentified patient-level data from an electronic health record-derived database that included patients with mBC who initiated third-line treatment with trastuzumab-based therapy combined with CT (Tras + CT; n = 288) or CT alone (CT; n = 49). Patients who received Tras + CT had a longer weighted median overall survival vs those who received CT only: 20.6 months (95% CI, 18.3-26.4 months) vs 10.1 months (95% CI, 7.8-12.3 months), respectively (hazard ratio [HR], 0.29; 95% CI, 0.16-0.53). This study provides additional support for maintaining trastuzumab-based therapies for patients with HER2+ mBC beyond second-line treatment. This treatment option should be available for all patients with mBC worldwide.

Current challenges and unmet needs in treating patients with human epidermal growth factor receptor 2-positive advanced breast cancer

Human epidermal growth factor receptor 2 oncogene (HER2-positive) overexpression/amplification occurs in less than 20% of breast cancers and has traditionally been associated with poor prognosis. Development of therapies that target HER2 has significantly improved outcomes for patients with HER2-positive advanced breast cancer (ABC). Currently available HER2-targeted agents include the monoclonal antibodies trastuzumab, pertuzumab, and margetuximab, the small-molecule inhibitors lapatinib, tucatinib, neratinib, and pyrotinib, as well as the antibody-drug conjugates trastuzumab emtansine and trastuzumab deruxtecan. Optimal sequencing of these agents in the continuum of the disease is critical to maximize treatment outcomes. The large body of clinical evidence generated over the past 2 decades aids clinicians in treatment decision-making. However, patients with HER2-positive ABC and specific disease characteristics and/or comorbidities, such as leptomeningeal disease, brain metastases, or cardiac dysfunction, are generally excluded from large randomized clinical trials, and elderly or frail patients are often underrepresented. In addition, there is great inequality in the accessibility of approved drugs across countries. This article addresses various challenging clinical situations when treating patients with HER2-positive ABC. The objective is to provide guidance to clinicians on how and when HER2-targeted therapies and additional treatments can be best implemented in routine clinical practice, on the basis of existing clinical evidence and expert opinion where needed.

Circular RNA hsa_circ_0001598 promotes programmed death-ligand-1-mediated immune escape and trastuzumab resistance via sponging miR-1184 in breast cancer cells

Approximately 25% of breast cancer (BC) patients are HER2-positive. Trastuzumab is used as a targeted therapy drug to treat HER2-positive BC patients; however, the drug resistance remains a big challenge. Circular RNAs (circRNAs) are reported to be involved in drug resistance, but the role of circ_0001598 has never been studied in BC. First, we identified the expression of circ_0001598 by RT-qPCR in BC. The gain-of-function and loss-of-function studies were applied to study the functional roles of circ_0001598 and its target gene. We observed upregulation of circ_0001598 in BC tissues, especially in trastuzumab-resistant BC samples. We further identified that miR-1184 is a functional target of circ_0001598. Moreover, it was found that programmed death-ligand 1 (PD-L1) was a direct target of miR-1184. The oncogenic effects of circ_0001598 in promoting BC cell growth, trastuzumab-resistance, PD-L1 expression, and escaping of CD8 T cell killing were abolished after the restoration of miR-1184. In conclusion, we demonstrate that circ_0001598/miR-1184/PD-L1 signaling plays a crucial role in the regulation of BC progression and trastuzumab-resistance phonotypes, which suggests that circ_0001598 may be a molecular target to treat HER2-positive BC patients.

Modeling Basins of Attraction for Breast Cancer Using Hopfield Networks

Cancer is a genetic disease for which traditional treatments cause harmful side effects. After two decades of genomics technological breakthroughs, personalized medicine is being used to improve treatment outcomes and mitigate side effects. In mathematical modeling, it has been proposed that cancer matches an attractor in Waddington's epigenetic landscape. The use of Hopfield networks is an attractive modeling approach because it requires neither previous biological knowledge about protein-protein interactions nor kinetic parameters. In this report, Hopfield network modeling was used to analyze bulk RNA-Seq data of paired breast tumor and control samples from 70 patients. We characterized the control and tumor attractors with respect to their size and potential energy and correlated the Euclidean distances between the tumor samples and the control attractor with their corresponding clinical data. In addition, we developed a protocol that outlines the key genes involved in tumor state stability. We found that the tumor basin of attraction is larger than that of the control and that tumor samples are associated with a more substantial negative energy than control samples, which is in agreement with previous reports. Moreover, we found a negative correlation between the Euclidean distances from tumor samples to the control attractor and patient overall survival. The ascending order of each node's density in the weight matrix and the descending order of the number of patients that have the target active only in the tumor sample were the parameters that withdrew more tumor samples from the tumor basin of attraction with fewer gene inhibitions. The combinations of therapeutic targets were specific to each patient. We performed an initial validation through simulation of trastuzumab treatment effects in HER2+ breast cancer samples. For that, we built an energy landscape composed of single-cell and bulk RNA-Seq data from trastuzumab-treated and non-treated HER2+ samples. The trajectory from the non-treated bulk sample toward the treated bulk sample was inferred through the perturbation of differentially expressed genes between these samples. Among them, we characterized key genes involved in the trastuzumab response according to the literature.