Influence of HER2 expression on prognosis in metastatic triple-negative breast cancer-results from an international, multicenter analysis coordinated by the AGMT Study Group

Impact of HER2 status on clinicopathological characteristics and pathological complete response to neoadjuvant chemotherapy in triple-negative breast cancer

PURPOSE

HER2-low triple-negative breast cancer (TNBC) accounted for up to 34%-39% of primary TNBC and 22.2%-32% of metastatic TNBC. Our study aims to explore the relationship between HER2 expression and clinicopathological characteristics, analyze the impact of HER2 expression on the pathological complete response (pCR) to neoadjuvant chemotherapy (NAC) in TNBC.

METHODS

This study involved 191 patients with TNBC who underwent operation after NAC from October 2021 to August 2022. Clinicopathological characteristics and the frequency of pCR were compared between HER2-low and HER2-0 TNBC.

RESULTS

42.2% (81/191) patients in our cohort were HER2-low. They exhibited differences in menopausal status, body mass index (BMI), androgen receptor (AR) expression, and histological grade (P < 0.05). Particularly, in HER2-low TNBC, AR was associated with tumor size, lymph node metastase, histological grade, and the incidence of multifocal disease (P < 0.05). The total pCR rate of entire cohor was 39.8%. Tumor size (P = 0.025), AR status (P = 0.033) and histological grade (P = 0.007) were significantly associated with the pCR rate of them, while the HER2 status did not exert a similar association. The multivariate analysis revealed that BMI (P = 0.004) and histological grade (P < 0.001) were associated with pCR of HER2-low TNBC, while tumor size (P = 0.034) and AR (P = 0.034) were associated with pCR of HER2-0 TNBC, respectively.

CONCLUSIONS

In our cohort, HER2-low TNBC patients exhibits specific clinical characteristics and response features to NAC.

Overall Survival and Prognostic Factors in Metastatic Triple-Negative Breast Cancer: A National Cancer Database Analysis

BACKGROUND

Metastatic triple-negative breast cancer (TNBC) is aggressive with poor median overall survival (OS) ranging from 8 to 13 months. There exists considerable heterogeneity in survival at the individual patient level. To better understand the survival heterogeneity and improve risk stratification, our study aims to identify the factors influencing survival, utilizing a large patient sample from the National Cancer Database (NCDB).

METHODS

Women diagnosed with metastatic TNBC from 2010 to 2020 in the NCDB were included. Demographic, clinicopathological, and treatment data and overall survival (OS) outcomes were collected. Kaplan-Meier curves were used to estimate OS. The log-rank test was used to identify OS differences between groups for each variable in the univariate analysis. For the multivariate analysis, the Cox proportional hazard model with backward elimination was used to identify factors affecting OS. Adjusted hazard ratios and 95% confidence intervals are presented.

RESULTS

In this sample, 2273 women had a median overall survival of 13.6 months. Factors associated with statistically significantly worse OS included older age, higher comorbidity scores, specific histologies, higher number of metastatic sites, presence of liver or other site metastases in those with only one metastatic site (excluding brain metastases), presence of cranial and extra-cranial metastases, lack of chemotherapy, lack of immunotherapy, lack of surgery to distant sites, lack of radiation to distant sites, and receipt of palliative treatment to alleviate symptoms. In the multivariate analysis, comorbidity score, histology, number of metastatic sites, immunotherapy, and chemotherapy had a statistically significant effect on OS.

CONCLUSIONS

Through NCDB analysis, we have identified prognostic factors for metastatic TNBC. These findings will help individualize prognostication at diagnosis, optimize treatment strategies, and facilitate patient stratification in future clinical trials.

Challenges in HER2-low breast cancer identification, detection, and treatment

Recently, human epidermal growth factor receptor 2 (HER2)-low breast cancer (BC) has emerged as a novel subset within the category of HER2-negative BC, prompting a reassessment of the immunohistochemical negative scores of 0, 1+, and the 2+/in situ hybridization (ISH) negative phenotype. Recent clinical trials have provided compelling evidence of the substantial clinical advantages offered by novel antibody-drug conjugates (ADCs) that target HER2 in the treatment of these specific tumor cohorts. Notably, trastuzumab deruxtecan (T-Dxd), an ADC that specifically targets HER2, has recently received approval from the US Food and Drug Administration as the inaugural targeted therapeutic option for HER2-low BC. However, the classification of HER2-low BC as a distinct subtype, the methods for detecting HER2-low BC, and the optimal treatment approach for HER2-low BC remain subjects of ongoing debate and lack consensus. This comprehensive review aims to address these pertinent concerns, offering insights into the nuanced tumor biology underlying HER2-low BC and critically analyzing the current treatment pathways available. By synthesizing available evidence, the objective is to contribute to an enhanced understanding of HER2-low BC, providing a foundation for more informed clinical decisions and further advancements in tailored therapeutic approaches. As the medical community navigates these uncertainties, this review seeks to consolidate existing knowledge, fostering a collective effort toward establishing consensus in the diagnosis and treatment of HER2-low BC.

Prognosis difference between HER2-low and HER2-zero breast cancer patients: a systematic review and meta-analysis

BACKGROUND

HER2-low breast cancer (BC) is proposed to be a special population of patients with an immunohistochemistry (IHC) score of 1 + or 2 + and non-amplified in situ hybridization (ISH) results. The role and prognostic impact of HER2-low BC is still controversial. This meta-analysis aims to explore the prognostic difference between of HER2-low and HER2-zero characteristic in BC patients.

METHODS

A meta-analysis was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and eligible studies were search in PubMed, Web of Science and EMBASE databases. Quality assessment of included studies were performed by Quality in Prognostic Studies (QUIPS) tool. Hazard ratios (HRs) and corresponding 95% confidence interval (CI) for overall survival (OS) and disease-free survival (DFS) were pooled in a meta-analysis. Furthermore, subgroup analysis, sensitivity analysis, and analysis for publication bias were conducted.

RESULTS

Eighteen studies comprising a total of 93,317 patients were included for meta-analysis. BC patients with HER2-low characteristic have longer OS (HRs 0.87, 95% CI 0.81-0.93, p < 0.0001) and DFS (HRs 0.82, 95% CI 0.73-0.93, p = 0.001) compared to those with HER2-zero characteristic. Subgroup analysis indicate that the source of heterogeneity may come from the hormone receptor (HR) status group. Although, the publication bias was detected, sensitivity analysis and the trim-and-fill method analysis demonstrated the stability and reliability of the results.

CONCLUSION

HER2-low BC patients have longer OS and DFS compared to HER2-zero BC patients, and its prognostic value is consistent among different HR status patients. Whether HER2-low breast cancer is an independent subtype of breast cancer is still a subject of ongoing research, and more studies are needed to fully understand the molecular and clinical features of this subtype.

Identification of Breast Cancer LCK Proto-Oncogene as a Master Regulator of TNBC Neutrophil Enrichment and Polarization

The role of neutrophils in breast cancer shows that the N1 proinflammatory subtype can suppress and attack the tumor. In contrast, the N2 pro-tumor subtype aids the tumor in its survival, progression, and metastasis. Recently, more focus has been directed to the role of innate myeloid cells, specifically neutrophils, in regulating the responses of lymphoid populations both in the progression of cancer and in response to therapy. However, the exact crosstalk between breast cancer cells and neutrophils is poorly understood. In this work, we used in-silico assays to investigate the role of the bidirectional effect of neutrophils on metastatic TNBC. Our reanalysis of publicly available data reveals that most TNBC's classified within the CE2 subtype are leukocyte-poor and have four major cell types in their ecotypes: dendritic cells, macrophages, fibroblasts, and epithelial cells. Further immune deconvolution of these patients revealed that a few cells significantly differed between groups, including macrophages, neutrophils, and T cells. All BC showed lower infiltrating neutrophils compared to healthy surrounding tissue. Treated TNBCs improved the count of infiltrating neutrophils in TNBC. Most TNBC patients have a unique CE2 ecotype, characterized by more basal-like epithelial cells, more neutrophils, and fewer mononuclear lymphocytes (B cells, macrophages M1, T cell CD4+ (non-regulatory), and T cell CD8+ and T regs). This can be related to our finding that CE2 TNBCs are characterized by a lower LCK and higher ERBB2, and their top DEGs are related to leukocyte activation and NFKB pathway.

Discordance of HER2-Low between Primary Tumors and Matched Distant Metastases in Breast Cancer

We examined differences in HER2 expression between primary tumors and distant metastases, particularly within the HER2-negative primary breast cancer cohort (HER2-low and HER2-zero). The retrospective study included 191 consecutive paired samples of primary breast cancer and distant metastases diagnosed between 1995 and 2019. HER2-negative samples were divided into HER2-zero (immunohistochemistry [IHC] score 0) and HER2-low (IHC score 1+ or 2+/in situ hybridization [ISH]-negative). The main objective was to analyze the discordance rate between matched primary and metastatic samples, focusing on the site of distant metastasis, molecular subtype, and de novo metastatic breast cancer. The relationship was determined by cross-tabulation and calculation of Cohen's Kappa coefficient. The final study cohort included 148 paired samples. The largest proportion in the HER2-negative cohort was HER2-low [primary tumor 61.4% (n = 78), metastatic samples 73.5% (n = 86)]. The discordance rate between the HER2 status of primary tumors and corresponding distant metastases was 49.6% (n = 63) (Kappa -0.003, 95%CI -0.15-0.15). Development of a HER2-low phenotype occurred most frequently (n = 52, 40.9%), mostly with a switch from HER2-zero to HER2-low (n = 34, 26.8%). Relevant HER2 discordance rates were observed between different metastatic sites and molecular subtypes. Primary metastatic breast cancer had a significantly lower HER2 discordance rate than secondary metastatic breast cancer [30.2% (Kappa 0.48, 95%CI 0.27-0.69) versus 50.5% (Kappa 0.14, 95% CI -0.03-0.32)]. This highlights the importance of evaluating potentially therapy-relevant discordance rates between a primary tumor and corresponding distant metastases.