Consensus on clinical diagnosis and medical treatment of HER2-low breast cancer (2022 edition)

Treatment of breast cancer with low expression of human epidermal growth factor receptor 2 (HER2; HER2-low) has drawn much attention in recent years. With the proven therapeutic effect of trastuzumab deruxtecan (T-DXd) in patients with HER2-low (immunohistochemistry [IHC] 1+, or IHC2+/in situ hybridization [ISH]-) breast cancer, HER2-low may become a new subtype of targeted therapy for breast cancer. The expert committee formulated this consensus based on the current clinical studies and clinical medication experience. The current consensus is the collaborative work of an interdisciplinary working group, including experts in the fields of pathology and oncology. The purpose of this consensus was to guide the clinical diagnosis and treatment of HER2-low breast cancer, thereby prolonging the overall survival of patients.

Think "HER2" different: integrative diagnostic approaches for HER2-low breast cancer

This work explores the complex field of HER2 testing in the HER2-low breast cancer era, with a focus on methodological aspects. We aim to propose clear positions to scientific societies, institutions, pathologists, and oncologists to guide and shape the appropriate diagnostic strategies for HER2-low breast cancer. The fundamental question at hand is whether the necessary tools to effectively translate our knowledge about HER2 into practical diagnostic schemes for the lower spectrum of expression are available. Our investigation is centered on the significance of distinguishing between an immunohistochemistry (IHC) score 0 and score 1+ in light of the clinical implications now apparent, as patients with HER2-low breast cancer become eligible for trastuzumab-deruxtecan treatment. Furthermore, we discuss the definition of HER2-low beyond its conventional boundaries and assess the reliability of established diagnostic procedures designed at a time when therapeutic perspectives were non-existent for these cases. In this regard, we examine potential complementary technologies, such as gene expression analysis and liquid biopsy. Ultimately, we consider the potential role of artificial intelligence (AI) in the field of digital pathology and its integration into HER2 testing, with a particular emphasis on its application in the context of HER2-low breast cancer.

Efficacy and safety of a pyrotinib-based regimen in non-small cell lung cancer patients harboring HER2 alterations: A real-world retrospective study

BACKGROUND

Pyrotinib, a novel irreversible pan-HER tyrosine kinase inhibitor, has been approved for the treatment of HER2-positive metastatic breast cancer in China. The aim of this study was to evaluate the efficacy and safety of pyrotinib in advanced nonsmall cell lung cancer (NSCLC) patients with HER2 alterations in real-world practice.

MATERIALS AND METHODS

A retrospective analysis of advanced NSCLC with HER2 mutations or amplifications who received pyrotinib-based treatment at the Qilu Hospital in Shandong University was performed. The primary end points were objective response rate and safety. The secondary end points were progression-free survival, disease control rate, and overall survival.

RESULTS

Twenty three eligible patients from a single center were enrolled between June 2019 and March 2023; among them, 21 had HER2 mutation and two harbored HER2 amplification. Evaluation of the efficacy in 21 patients revealed an objective response rate of 28.6% (6/21; 95% confidence interval [CI]: 7.5%-49.6%) and disease control rate of 85.7% (18/21). The median progression-free survival and overall survival were 7.7 months (95% CI: 6.07-9.33) and 20.8 months (95% CI: 8.42-33.18), respectively. The most common adverse events (AEs) included diarrhea (n = 14, 60.9%), nausea (n = 5, 21.7%), and liver dysfunction (n = 5, 21.7%). Seven patients (7/23, 30.4%) had grade 3-4 AE; no grade 5 AE was observed. Furthermore, one patient (1/23, 4.3%) experienced dose withdrawal and two (2/23, 8.7%) presented with dose reduction symptoms.

CONCLUSION

Pyrotinib-based therapy showed promising antitumor activity and acceptable safety in advanced NSCLC patients with HER2 alterations.

Immunotherapy as a later-line option for HER2-altered advanced non-small-cell lung cancer: taxane might be a favorable partner

Aim: To assess the effectiveness of different types of taxanes, including nab-paclitaxel, paclitaxel and docetaxel, and further compare the effectiveness of taxane-based chemotherapy, taxane-based chemotherapy plus angiogenesis inhibitors or taxane-based chemotherapy plus immune checkpoint inhibitors in HER2-altered non-small-cell lung cancer in the second- or third-line setting. Materials & methods: A total of 52 patients were included in the study. Progression-free survival was compared between subgroups. Results: A clinically meaningful improvement in progression-free survival was observed among patients in the nab-paclitaxel group compared with the docetaxel group. Taxane-based chemotherapy plus immune checkpoint inhibitors achieved longer progression-free survival than taxane-based chemotherapy. There was no difference between taxane-based chemotherapy plus immune checkpoint inhibitors and taxane-based chemotherapy plus angiogenesis inhibitors. Conclusion: Nab-paclitaxel appears to be a reasonable alternative to docetaxel. Chemotherapy plus immune checkpoint inhibitors might yield more survival benefits than chemotherapy alone.

Efficacy and safety of trastuzumab deruxtecan in the treatment of HER2-low/positive advanced breast cancer: a single-arm meta-analysis

Background: Clinical trials have shown that the use of trastuzumab deruxtecan (DS-8201) alone is expected to provide novel therapeutic options for HER2-low/positive patients. Nevertheless, there are some variations in the efficacy of trial results, with potential risks at the safety level. Most DS-8201 trials in HER2 advanced breast cancer (ABC) have been conducted in the form of small-sample nonrandomized controlled studies, resulting in a lack of validated indicators to evaluate the efficacy and safety of DS-8201. Thus, this meta-analysis aimed to pool the results of various trials of DS-8201 alone to explore the efficacy and safety of DS-8201 in patients with HER2-low/positive advanced breast cancer. Methods: Relevant studies were searched in seven databases, including Embase, PubMed, Web of Science, Cochrane Library, CNKI, VIP database and WanFang data, to collect single-arm studies on DS-8201 for HER2-low/positive ABC. MINORS was adopted for quality assessment and STATA 16.0 for data analysis. Results: Ten studies involving 1,108 patients were included in this meta-analysis. As for the tumor response rate, the pooled ORR and DCR of all studies reached 57% (95% CI: 47%-67%) and 92% (95% CI: 89%-96%) respectively, and the pooled ORRs of the HER2-low expression group and the HER2-positive expression group were 46% (95% CI: 35%-56%) and 64% (95% CI: 54%-74%). Only the low expression group achieved median survival time, with a pooled median PFS and median OS of 9.24 (95% CI: 7.54-10.94) months and 23.87 (95% CI: 21.56-26.17) months, respectively. The most common treatment-related adverse events from DS-8201 were nausea (all grades: 62%; ≥ grade III: 5%), fatigue (all grade: 44%; ≥ grade III: 6%), and alopecia (all grades: 38%; ≥ grade III: 0.5%). Drug-related interstitial lung disease or pneumonitis occurred in 13% of the 1,108 patients, with only a 1% incidence of AE ≥ grade III. Conclusion: The present study suggests that DS-8201 is effective and safe in the treatment of ABC with low or positive HER2 expression, providing additional relevant information for its clinical application. However, further strengthening of the pairs is needed, as well as more clinical studies to support individualized treatment. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023390316.

HER2 Low Breast Cancer: A New Subtype or a Trojan for Cytotoxic Drug Delivery?

Despite the great progress made in the understanding of the biological behavior of certain types of invasive breast cancer, there is still no single histological or molecular classification that encompasses such diversity and accurately predicts the clinical course of distinct breast cancer subtypes. The long-lasting classification of breast cancer as HER2-positive vs. HER2-negative has recently come into question with the discovery of new antibody drug conjugates (ADC), which are proven to be remarkably efficient in treating HER2-low breast cancer. The HER2-low paradigm has challenged the traditional understanding of HER2 overexpression and emphasized the need for more robust HER2 testing in order to encompass HER2 intratumoral heterogeneity and spatial distribution more accurately. It is yet to be seen if low HER2 will remain merely a marker of HER2-equipped tumors targetable with ADCs or if distinctive molecular and phenotypic groups within HER2-low tumors will eventually be discerned.

S. B, Chatterjee M, Prabhash K, Sreekanthreddy P, Rishi KD, Goswami HM, Veldore VH. An absolute approach to using whole exome DNA and RNA workflow for cancer biomarker testing

Introduction

The concept of personalized medicine in cancer has emerged rapidly with the advancement of genome sequencing and the identification of clinically relevant variants that contribute to disease prognosis and facilitates targeted therapy options. In this study, we propose to validate a whole exome-based tumor molecular profiling for DNA and RNA from formalin-fixed paraffin-embedded (FFPE) tumor tissue.

Methods

The study included 166 patients across 17 different cancer types. The scope of this study includes the identification of single-nucleotide variants (SNVs), insertions/deletions (INDELS), copy number alterations (CNAs), gene fusions, tumor mutational burden (TMB), and microsatellite instability (MSI). The assay yielded a mean read depth of 200×, with >80% of on-target reads and a mean uniformity of >90%. Clinical maturation of whole exome sequencing (WES) (DNA and RNA)- based assay was achieved by analytical and clinical validations for all the types of genomic alterations in multiple cancers. We here demonstrate a limit of detection (LOD) of 5% for SNVs and 10% for INDELS with 97.5% specificity, 100% sensitivity, and 100% reproducibility.

Results

The results were >98% concordant with other orthogonal techniques and appeared to be more robust and comprehensive in detecting all the clinically relevant alterations. Our study demonstrates the clinical utility of the exome-based approach of comprehensive genomic profiling (CGP) for cancer patients at diagnosis and disease progression.

Discussion

The assay provides a consolidated picture of tumor heterogeneity and prognostic and predictive biomarkers, thus helping in precision oncology practice. The primary intended use of WES (DNA+RNA) assay would be for patients with rare cancers as well as for patients with unknown primary tumors, and this category constitutes nearly 20–30% of all cancers. The WES approach may also help us understand the clonal evolution during disease progression to precisely plan the treatment in advanced stage disease.

Prognostic impact of HER2-low expression in HER2-negative breast cancer under different hormone receptor status

BACKGROUND

HER2-low expression in breast cancer has received increasing attention as a target for novel antibody-drug conjugates (ADCs). The purpose of this study was to investigate the impact of HER2-low status on survival outcomes in patients with HER2-negative early breast cancer.

METHODS

Medical records of patients with HER2-negative non-metastatic breast cancer who were treated at our institution from January 2008 and June 2019 were retrospectively reviewed. The main outcome measurements of our study were overall survival (OS) and disease-free survival (DFS), which were compared between the HER2-low and HER2-0 groups stratified by hormone receptor (HR) status.

RESULTS

A total of 2605 HER2-negative cases were identified, of which 1418 (54.4%) had HER2-low and 1187 (45.6%) had HER2-0 disease. The proportion of HER2-low tumors was significantly higher in HR-positive tumors than in HR-negative tumors. No significant difference was observed in DFS and OS between the HER2-low and HER2-0 groups in univariate analyses, regardless of HR status. Multivariate analysis of the Cox proportional hazard regression model revealed that HER2-low was independently associated with improved OS in patients with HR-negative disease (HR 0.32, 95% CI 0.13-0.80, p = 0.015).

CONCLUSION

Our findings demonstrate that the prognostic impact of low HER2 expression varies according to HR status, with slightly favorable outcomes among HER2-low tumors in patients with HR-negative disease.

Retrospective Study on the Efficacy and Safety of Pyrotinib-Based Therapy for HER2-Positive Nonbreast Advanced Solid Tumors

Background

Human epidermal growth factor receptor 2 (HER2) is a member of the large ErbB family and an important oncogene in many solid tumors. Pyrotinib has been approved for the treatment of HER2-positive, recurrent, or metastatic breast cancer. However, there are very few clinical studies on pyrotinib in other HER2-positive solid tumors. Therefore, more evidence of clinical research is impendently needed to shepherd pyrotinib-based therapy in HER2-positive nonbreast advanced solid tumors. Patients and Methods. We performed a retrospective analysis of HER2-positive nonbreast advanced solid tumors patients with HER2 amplification or mutations who were administered with pyrotinib-based therapy in Henan Cancer Hospital between July 1, 2019, and December 2, 2021. In our research, 25 eligible patients were included with 16 patients with lung cancer, 6 patients with gastric cancer, 2 patients with colorectal cancer, and 1 patient with cholangiocarcinoma. Progression-free survival (PFS) is our main research end point.

Results

The median PFS was 188 days (95% CI: 83–not reached (NR)), and overall survival (OS) was 250 days (95% CI: 188–NR), respectively. 16 patients with lung cancer had a median PFS of 204 days (95% CI: 55–NR) and 6 patients with gastric cancer had PFS of 142 days (95% CI: 83–NR), respectively. The median OS was 366 days (95% CI: 248–NR) in patients with lung cancer and 179 days (95% CI: 90–NR) in patients with gastric cancer. The median PFS and OS of patients receiving >3 line treatment were lower than those receiving ≤3 line treatment (PFS: 188 days vs 204 days, p = 0.92; OS: 188 days vs 366 days, p = 0.43). All 25 patients can be evaluated. The objective response rate (ORR) was 24%, and the disease control rate (DCR) was 68%. Lung cancer ORR was 25%, and gastric cancer ORR was 16.7%. In addition, the DCR of lung cancer was 62.5% and that of gastric cancer was 66.7%. In addition, the ORR and DCR of patients receiving treatment ≤3 lines were higher than those receiving treatment >3 lines (ORR: 35.7% vs 9.1%, p = 0.18; DCR: 71.4% vs 63.6%, p > 0.99). The most common treatment-related adverse events (TRAEs) were diarrhea (84%), but only 3 patients (12%) reported grade 3 diarrhea with good control.

Conclusion

These results show that in HER2-positive nonbreast advanced solid tumors, the treatment based on pyrotinib regimen has good antitumor activity and acceptable safety. This retrospective study aims to promote larger clinical studies to further clarify the efficacy and safety of pyrotinib in the treatment of nonbreast solid tumors.

First-line immunotherapy or angiogenesis inhibitor plus chemotherapy for HER2-altered NSCLC: a retrospective real-world POLISH study

Background:

There have been no comprehensive large-scale studies that have evaluated the benefits of chemotherapy-based regimens in addressing HER2-altered advanced non-small-cell lung cancer (NSCLC) in a first-line setting. Data on HER2 alteration subtypes and concomitant alterations are also limited. Accordingly, our retrospective, real-world POLISH study assesses the efficacy of first-line chemotherapy alone (C) as well as combinations with immune checkpoint inhibitors (C + I) or angiogenesis inhibitors (C + A) for HER2-altered NSCLC; molecular features are also reported.

Methods:

HER2-altered NSCLC patients who received a first-line treatment between November 2015 and September 2021 were screened. Patients treated with C, C + I, or C + A were included in our final efficacy analysis. Progression-free survival (PFS) was compared between the subgroups. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was performed to evaluate concomitant alterations.

Results:

A total of 293 patients were screened, with an identification of HER2 amplification and 37 distinct HER2 mutations, and 210 cases treated with C, C + I, or C + A were ultimately included. C + A achieved longer PFS than C (5.63 vs 4.03 months, hazard ratio: 0.64, 95% confidence interval [CI]: 0.46–0.88, p = 0.006). C + I did not improve median PFS compared to C + A or C (both p > 0.05), despite the programmed cell death ligand-1 (PD-L1) expression or tumor mutational burden. KEGG analysis revealed that concomitant upregulation of PI3 K/AKT pathway signaling was common in HER2-altered NSCLC.

Conclusion:

Chemotherapy plus angiogenesis inhibitors may yield a greater survival benefit than chemotherapy alone in a first-line setting for HER2-altered NSCLC, whereas an immune-based combination therapy may not be superior to a sole chemotherapy regimen. Activation of PI3 K/AKT signaling may mediate immunosuppression in HER2-altered NSCLC.

In Real Life, Low-Level HER2 Expression May Be Associated With Better Outcome in HER2-Negative Breast Cancer: A Study of the National Cancer Center, China

Background

To characterize the clinical and pathological features and survival of patients with human epidermal growth factor receptor 2 (HER2)-low breast cancer in China.

Methods

The China National Cancer Center database was used to identify 1,433 metastatic breast cancer patients with HER2-negative disease diagnosed between 2005 and 2015. Clinicopathological features, survival, and prognosis information were extracted. Overall survival (OS) was estimated using the Kaplan–Meier method and compared using the log-rank test. Prognostic factors associated with OS were analyzed using Cox regression model with 95% confidence interval (95% CI).

Results

There were 618 (43.1%) and 815 (56.9%) HER2-low and HER2-zero tumors out of 1,433 tumors, respectively. The proportion of hormone receptor (HR)-positive tumors was significantly higher in HER2-low tumors than in those with HER2-zero tumors (77.8% vs. 69.2%, p < 0.001). Patients with HER2-low tumors survived significantly longer than those with HER2-zero tumors in the overall population (48.5 months vs. 43.0 months, p = 0.004) and HR-positive subgroup (54.9 months vs. 48.1 months, p = 0.011), but not in the HR-negative subgroup (29.5 months vs. 29.9 months, p = 0.718). Multivariate regression analysis revealed that HER2-low tumors were independently associated with increased OS in HER2-negative population (HR: 0.85, 95% CI: 0.73–0.98, p = 0.026).

Conclusion

Our findings demonstrate that HER2-low tumors could be identified as a more distinct clinical entity from HER2-zero tumors, especially for the HR-positive subgroup. A more complex molecular landscape of HER2-low breast cancer might exist, and more precise diagnostic algorithms for HER2 testing could be investigated, thus offering new therapeutic targets for breast cancer treatment.

Pyrotinib in HER2 heterogeneously mutated or amplified advanced non-small cell lung cancer patients: a retrospective real-world study (PEARL)

Human epidermal growth factor receptor 2 (HER2) amplification or activating mutations are found in 1.6%-4% of non-small cell lung cancer (NSCLC). Pyrotinib has been reported to have better potency in NSCLC patients with HER2 exon 20 insertion (ex20ins) mutations; however, more clinical evidence is urgently needed to guide pyrotinib-based therapy in NSCLC with HER2 amplification or heterogeneous mutations. We retrospectively analyzed advanced NSCLC patients with HER2 amplification or mutations who were treated with pyrotinib-based therapy between September 25, 2018 and October 30, 2020 in our hospital. Molecular dynamics simulation was used to explore the bioactive conformation and binding mechanisms of pan-ErbB tyrosine kinase inhibitors (TKIs) including pyrotinib for different HER2 ex20ins variants. In this study, 79 eligible patients were included with 70 ex20ins variants, 6 missense mutations and 3 primary HER2 amplifications identified. A775_G776insYVMA insertion was the most common observed subtype. The median progression-free survival (mPFS) was 5.8 (95% CI: 4.1-7.4) months. Use of pyrotinib-based therapy in first-/second-line settings showed a significantly better prognosis than that observed in third-line settings or above (mPFS: 9.1 vs. 4.4 months; P = 0.0003). Compared with HER2 amplification and exon 20 non-YVMA insertion variants, patients with HER2 missense mutations had a visible mPFS benefit (12.2 vs. 6.8 vs. 5.2 months). Computational docking simulations revealed that pyrotinib failed to interact with the specific insertion variant P780_Y781insGSP. These results indicated that pyrotinib-based therapy exhibited good anti-tumor activity and acceptable safety profile in HER2-altered advanced NSCLC.