Clinicopathologic characteristics and prognostic significance of HER2-low expression in patients with early breast cancer: A systematic review and meta-analysis

Breast biomarkers evolution between primary and distant metastasis: incidence and significance

AIMS

To evaluate the evolution when breast cancer (BC) is classified as three clinical profiles and five clinical profiles by incorporating human epidermal growth factor 2 (HER2)-low to the biomarkers' profile.

METHODS AND RESULTS

BC with distant metastasis that has document hormonal receptors (HR) (positive, negative) and HER2 (positive, low, zero) results were included (n = 161). Cases were categorised into three clinical profiles (HR-positive/HER2-negative, HER2-positive and TNBC) and five (HR-positive/HER2-zero, HR-positive/HER2-low, HR-negative/HER2-zero, HR-negative/HER2-low, HR-positive or negative/HER2-positive). Evolution occurred in 22.4% cases when three clinical profiles were analysed and 36.6% considering five clinical profiles. There were no statistically significant differences among the three clinical profiles in overall survival (OS). When five clinical profiles were analysed, HR-negative/HER2-zero had the worst OS with HzR = 6.82 and 95% confidence interval (CI) =1.19, 39.23, P = 0.031. In the multivariable analysis, ER-positive was associated with HER2 discordance less than oestrogen receptor (ER)-negative with odds ratio (OR) = 0.354 and 95% CI = 0.14-0.88, P = 0.025. In the multivariable analysis, patients with Eastern Cooperative Oncology Group 2+ had worse OS with hazard ratio (HzR) = 5.54 and 95% CI = 2.4-12.79, P < 0.0001. HR concordant had better OS with HzR = 0.34 and 95% CI = 0.2-0.63, P = 0.0004. HER2 conversion from low to zero had worse OS than HER2 concordance with HzR 2.66 and 95% CI = 1.21-5.83, P = 0.015.

CONCLUSIONS

Five-profile classification provides a more accurate idea about the rate of potential change in treating BC in the metastatic setting.

Prognosis in HR-positive metastatic breast cancer with HER2-low versus HER2-zero treated with CDK4/6 inhibitor and endocrine therapy: a meta-analysis

Background

The combination of CDK4/6 inhibitors (CDK4/6i) and endocrine therapy (ET) is currently the standard first-line treatment for patients with metastatic hormone receptor positive (HR+), and HER2-negative (HER2-) breast cancer. However, the impact of HER2 status on the prognosis of patients receiving CDK4/6i and ET remains unclear. The meta-analysis was conducted to evaluate different outcomes between HER2-low and HER2-zero patients in advanced HR+ breast cancer receiving CDK4/6i and ET.

Methods

A systematic search was performed in PubMed and EMBASE databases for relevant published literature. Objective response rate (ORR), overall survival (OS), and progression-free survival (PFS) were pooled by fixed or random effects models.

Results

Overall, 12 studies with 3567 patients were eligible for analysis. The pooled analysis suggested that no significant differences were observed in terms of ORR and OS between HER2-low and HER2-zero patients who underwent CDK4/6i and ET. Similarly, no significant difference in PFS was found between HER2-low and HER2-zero patients who underwent post-line CDK4/6i and ET or first-line Palbociclib and ET. However, in patients who received mixed-line (not a single treatment line) or first-line CDK4/6i and ET, the PFS was significantly shorter in the HER2-low subgroup than in the HER2-zero subgroup (mixed-line: HR = 1.36; 95% CI = 1.11-1.65; P = 0.002; first-line: HR = 1.14; 95% CI = 1.01-1.28; P = 0.04). A similar phenomenon was observed in patients who received mixed-line or post-line Palbociclib and ET (mixed-line: HR = 1.60; 95% CI = 1.09-2.34; P = 0.02; post-line: HR = 1.43; 95% CI = 1.03-2.00; P = 0.03).

Conclusion

These results indicated that HER2-low status did not have a significant association with ORR and OS, but it may have a worse impact on PFS in patients who received mixed-line or first-line CDK4/6i and ET, as well as mixed-line or post-line palbociclib plus ET.

The Performance and Clinical Applicability of HER2 Digital Image Analysis in Breast Cancer: A Systematic Review

This systematic review aims to address the research gap in the performance of computational algorithms for the digital image analysis of HER2 images in clinical settings. While numerous studies have explored various aspects of these algorithms, there is a lack of comprehensive evaluation regarding their effectiveness in real-world clinical applications. We conducted a search of the Web of Science and PubMed databases for studies published from 31 December 2013 to 30 June 2024, focusing on performance effectiveness and components such as dataset size, diversity and source, ground truth, annotation, and validation methods. The study was registered with PROSPERO (CRD42024525404). Key questions guiding this review include the following: How effective are current computational algorithms at detecting HER2 status in digital images? What are the common validation methods and dataset characteristics used in these studies? Is there standardization of algorithm evaluations of clinical applications that can improve the clinical utility and reliability of computational tools for HER2 detection in digital image analysis? We identified 6833 publications, with 25 meeting the inclusion criteria. The accuracy rate with clinical datasets varied from 84.19% to 97.9%. The highest accuracy was achieved on the publicly available Warwick dataset at 98.8% in synthesized datasets. Only 12% of studies used separate datasets for external validation; 64% of studies used a combination of accuracy, precision, recall, and F1 as a set of performance measures. Despite the high accuracy rates reported in these studies, there is a notable absence of direct evidence supporting their clinical application. To facilitate the integration of these technologies into clinical practice, there is an urgent need to address real-world challenges and overreliance on internal validation. Standardizing study designs on real clinical datasets can enhance the reliability and clinical applicability of computational algorithms in improving the detection of HER2 cancer.

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.

Prognostic factors in non-metastatic HER2 'low' and HER2 'negative' breast cancer: single institute experience

AIM

Comparison of prognosis and survival in human epidermal growth factor receptor 2 (HER2)-low and HER2-negative patients with early stage or locally advanced, hormone receptor-positive breast cancer.

MATERIAL AND METHODS

In a retrospective single center study, the patients with early stage or locally advanced stage, hormone receptor (HR)-positive [estrogen receptor (ER) ≥ 1% and/or progesterone receptor (PR) ≥ 1%] and HER2 negative or HER2 low invasive breast cancer diagnosis were included. A total of 444 patients were included in the study. Patients were divided into two groups: HER2 negative and HER2 low. There were 235 (53%) patients in the HER2 negative group and 209 (47%) patients in the HER2 low group.

RESULTS

The HER2 low group had significantly longer 5‑year disease-free survival (DFS) than the HER2 negative group. The patients with lower Ki67 (< 20%) also had a longer 5‑year DFS.

CONCLUSION

Nonmetastatic HR+/HER2 low breast cancer patients had better DFS than HR+/HER2 negative ones. The Ki67 level and HER2 low status were independent prognostic factors. Randomized clinical trials are needed in early stage HER2 low breast cancer patients.

Do HER2-Low Tumors Have a Distinct Clinicopathologic Phenotype?

BACKGROUND

Breast cancer subtypes, distinguished by hormone receptor (HR) and HER2 status, have different clinicopathologic features. With recognition of the clinical relevance of HER2-low, there is debate as to whether this is a distinct subtype. Our study aimed to determine whether HER2-low breast cancers have specific clinicopathologic features that differ from those of HER2-negative and HER2-positive cancers.

PATIENTS AND METHODS

A total of 11,072 patients undergoing upfront surgery from 1998 to 2010 were identified from a single-institution prospectively maintained database. HER2 status was classified by immunohistochemistry (IHC)/fluorescence in situ hybridization (FISH) as HER2 negative (41.2%), HER2 low (45%; IHC 1+ or 2+ with negative FISH), and HER2 positive (13.7%), and stratified by HR status. Univariate (UVA) and multivariable multinomial logistic regression analysis (MVA) were performed to determine associations among variables and subtypes.

RESULTS

Compared with HER2-negative tumors, HER2 low was associated with lymphovascular invasion [odds ratio (OR) 1.2, 95% confidence interval (CI) 1.06-1.36; p = 0.003], multifocality (OR 1.26, 95% CI 1.12-1.42; p < 0.001), nodal micrometastasis (OR 1.15, 95% CI 1.02-1.31; p = 0.024), and lower rates of ≥ 3 positive nodes (OR 0.77, 95% CI 0.66-0.90, p = 0.001). When stratified by HR expression, in both HR-positive and HR-negative tumors, age and multifocality were associated with HER2 low on UVA. On MVA, no variables were independently associated with both HR-negative and HR-positive/HER2-low tumors compared with HER2-negative tumors. In contrast, HER2-positive tumors, regardless of HR status, were associated with multifocality and an extensive intraductal component.

CONCLUSION

Clinicopathologic features of HER2-low tumors appear to be primarily related to HR status. Our findings do not support the characterization of HER2 low as a separate subtype.

Development and Validation of MRI Radiomics Models to Differentiate HER2-Zero, -Low, and -Positive Breast Cancer

BACKGROUND. Breast cancer HER2 expression has been redefined using a three-tiered system, with HER2-zero cancers considered ineligible for HER2-targeted therapy, HER2-low cancers considered candidates for novel HER2-targeted drugs, and HER2-positive cancers treated with traditional HER2-targeted medications. OBJECTIVE. The purpose of this study was to assess MRI radiomics models for a three-tiered classification of HER2 expression of breast cancer. METHODS. This retrospective study included 592 patients with pathologically confirmed breast cancer (mean age, 47.0 ± 18.0 [SD] years) who underwent breast MRI at either of a health system's two hospitals from April 2016 through June 2022. Three-tiered HER2 status was pathologically determined. Radiologists assessed the conventional MRI features of tumors and manually segmented the tumors on multiparametric sequences (T2-weighted images, DWI, ADC maps, and T1-weighted delayed contrast-enhanced images) to extract radiomics features. Least absolute shrinkage and selection operator analysis was used to develop two radiomics signatures, to differentiate HER2-zero cancers from HER2-low or HER2-positive cancers (task 1) as well as to differentiate HER2-low cancers from HER2-positive cancers (task 2). Patients from hospital 1 were randomly assigned to a discovery set (task 1: n = 376; task 2: n = 335) or an internal validation set (task 1: n = 161; task 2: n = 143); patients from hospital 2 formed an external validation set (task 1: n = 55; task 2: n = 50). Multivariable logistic regression analysis was used to create nomograms combining radiomics signatures with clinicopathologic and conventional MRI features. RESULTS. AUC, sensitivity, and specificity in the discovery, internal validation, and external validation sets were as follows: for task 1, 0.89, 99.4%, and 69.0%; 0.86, 98.6%, and 76.5%; and 0.78, 100.0%, and 0.0%, respectively; for task 2, 0.77, 93.8%, and 32.3%; 0.75, 92.9%, and 6.8%; and 0.77, 97.0%, and 29.4%, respectively. For task 1, no nomogram was created because no clinicopathologic or conventional MRI feature was associated with HER2 status independent of the MRI radiomics signature. For task 2, a nomogram including an MRI radiomics signature and three pathologic features (histologic grade of III, high Ki-67 index, and positive progesterone receptor status) that were independently associated with HER2-low expression had an AUC of 0.87, 0.83, and 0.80 in the three sets. CONCLUSION. MRI radiomics features were used to differentiate HER2-zero from HER2-low cancers or HER2-positives cancers as well as to differentiate HER2-low cancers from HER2-positive cancers. CLINICAL IMPACT. MRI radiomics may help select patients for novel or traditional HER2-targeted therapies, particularly those patients with ambiguous results of immunohistochemical staining results or limited access to fluorescence in situ hybridization.

Clinical, Epidemiologic, and Pathologic Significance of ERBB2-Low Expression in Breast Cancer

Importance

It is unclear whether breast cancer (BC) with low ERBB2 expression (ERBB2-low) is a distinct clinical, pathological, and epidemiological entity from BC classified as no ERBB2 expression (ERBB2-negative).

Objective

To evaluate the clinical, pathological, and epidemiologic features of BC with ERBB2-low expression compared with ERBB2-negative BC in a large population study.

Design, Setting, and Participants

This cohort study was conducted as part of the Pathways Study, a prospective, racially and ethnically diverse cohort study of women with BC enrolled between 2006 and 2013 in Kaiser Permanente Northern California (KPNC). The hematoxylin and eosin slides underwent centralized pathology review, including the percentage of tumor infiltrating lymphocytes (TILs). Breast biomarker results were extracted from pathology reports, and women were included if they had a documented ERBB2 value that was not classified ERBB2-positive. Data were analyzed from February 2023 through January 2024.

Exposure

Clinical and tumor characteristics associated with BC and ERBB2-low or ERBB2-negative status.

Main Outcome and Measures

ERBB2-low was defined as immunohistochemistry score of 1+ or 2+ (negative by in situ hybridization); ERBB2-negative was defined as immunohistochemistry score of 0+. Other data were collected by self-report or extraction from electronic health records, including BC risk factors, tumor characteristics, treatment modality, and survival outcomes, with recurrence-free survival (RFS) as the primary outcome and overall survival (OS) and BC-specific mortality (BCSM) as secondary outcomes. The clinical, pathological, and epidemiological variables were compared between ERBB2-low and ERBB2-negative BC.

Results

Of 2200 eligible patients (all female; with mean [SD] age, 60.4 [11.9] years), 1295 (57.2%) had tumors that were ERBB2-low. Hormone receptors were positive in 1956 patients (88.9%). The sample included 291 Asian patients (13.2%), 166 Black patients (7.5%), 253 Hispanic patients (11.5%), 1439 White patients (65.4%), and 51 patients (2.3%) who identified as other race or ethnicity (eg, American Indian or Alaska Native and Pacific Islander). Within the hormone receptor-negative group, patients whose tumors had ERBB2-low staining, compared with those with ERBB2-negative tumors, had better OS (hazard ratio [HR], 0.54; 95% CI, 0.33-0.91; P = .02), RFS (HR, 0.53; 95% CI, 0.30-0.95; P = .03), and BCSM (HR, 0.43; 95% CI, 0.22-0.84; P = .01). In multivariable survival analysis stratified by hormone receptor status and adjusted for key covariates, patients with ERBB2-low and hormone receptor-negative tumors had lower overall mortality (HR, 0.48; 95% CI, 0.27-0.83; P = .009), RFS (HR, 0.45; 95% CI, 0.24-0.86; P = .02), and BCSM (subdistribution HR, 0.21; 95% CI, 0.10-0.46; P < .001) compared with patients with ERBB2-negative and hormone receptor-negative tumors. Within the hormone receptor-negative subtype, patients with ERBB2-low and high TILs tumors had better survival across all 3 outcomes compared with patients with ERBB2-negative and low TILs tumors. Additionally, patients with ERBB2-low and low TILs tumors had better BCSM (subdistribution HR, 0.36; 95% CI, 0.14-0.92; P = .03).

Conclusions and Relevance

These findings suggest that there were clinical, pathological, and epidemiological differences between ERBB2-low and ERBB2-negative BC, raising the possibility that ERBB2-low might be a unique biologic entity.

Prognostic value and relapse pattern of HER2-low in hormone receptor-positive breast cancer

BACKGROUND

A new concept of HER2-low has emerged in recent years. However, the prognostic value and the relapse pattern of HER2-low is unclear.

METHODS

Our study included patients diagnosed with HER2-negative/hormone receptor-positive breast cancer to explore the differences in survival outcomes between the HER2-low group and the HER2-zero group. More importantly, we explored different recurrence patterns, including the comparison of metastatic sites and recurrence time curve between the two groups.

RESULTS

A total of 797 patients with hormone receptor-positive breast cancer were analyzed. Similar disease-free survival (DFS) was observed between the HER2-low group and HER2-zero group (HR 0.84, 95% CI: 0.61-1.16, p = 0.290). There was also no significant difference in OS between the HER2-low group and the HER2-zero group (HR 0.77, 95% CI: 0.46-1.28, p = 0.310). When IHC 1+ and 0 were taken as a group, the IHC 2+ group had significantly better DFS than the IHC 1+ and 0 group in some subgroups. The risk of bone metastasis in patients with HER2 IHC 1+ and 0 was significantly higher than that of patients with HER2 IHC 2+ (12.7% vs. 4.7%, p < 0.001). Compared with the HER2-zero group, we found that the HER2-low group had a more obvious peak in mortality at the time of postoperative 80th-100th month.

CONCLUSIONS

No significant difference in DFS and OS between the HER2-low group and the HER2-zero group was observed. Patients with HER2 IHC 1+ and 0 tend to develop bone metastasis. The HER2-low group had a more obvious second peak in mortality.