Comparison of clinicopathological characteristics and response to neoadjuvant chemotherapy between HER2-low and HER2-zero breast cancer

Molecular and clinical traits of HER2-low breast cancer patients and their relationship with neoadjuvant treatment effectiveness

BACKGROUND

We aimed to investigate the clinical and molecular characteristics of different degrees of human epidermal growth factor receptor 2 (HER2) protein expression in HER2-negative breast cancer and the related factors affecting the efficacy of neoadjuvant chemotherapy in HER2-low breast cancer patients.

METHODS

The study endpoint was pathological complete remission (PCR). Blood specimens and fresh cancer tissue samples were collected before neoadjuvant chemotherapy for whole-exon sequencing (WES) and RNA sequencing (RNA-seq), and patients were divided into a human epidermal growth factor receptor 2 (HER2)-low group and a HER2-0 group according to their HER2 expression status via bioinformatics analysis.

RESULTS

A total of 409 HER2-negative breast cancer patients were included in the analysis, and HER2 status (HER2-0 vs. HER2-low) was significantly different between hormone receptor status, the Ki-67 index, and the PCR rate. A total of 18 patients who underwent WES and RNA testing were included, and the WES results suggested that the HER2-low group had a significantly higher rate of PIK3CA mutations and a greater frequency of PI3K pathway variants than the other groups and the HER2-low group had a greater number of concomitant mutations and reached statistical significance ( P  = 0.03). In terms of expression profiles, HER2-low and HER2-0 patients had different expression profiles. Overall, suggesting that the low PCR rate in the HER2-low group may also be related to chemoresistance.

CONCLUSION

Our investigation highlights the possibility that HER2-low breast cancer may indicate a unique clinical and biological phenomenon.

Pathologic response rates in HER2-low versus HER2-zero early breast cancer patients receiving neoadjuvant therapy: a systematic review and meta-analysis

BACKGROUND

Currently, the primary methods for detecting HER2 expression levels are immunohistochemistry (IHC) and in situ hybridization (ISH), with the traditional standard being a HER2-positive score of 3 + accompanied by ERBB2 gene amplification detected through ISH. However, a new entity has recently emerged: HER2-low, defined as HER2 IHC 1 + or 2 + with negative ISH. HER2-low breast cancer, representing 45-60% of all HER2-negative tumors, has distinct biological characteristics and uncertain responses to conventional HER2-targeted therapies. Recent studies suggest varied clinical outcomes, highlighting the need for further investigation into the impact of HER2-low status on treatment efficacy and prognosis.

OBJECTIVE

This meta-analysis evaluates the difference in complete pathological response (pCR), disease-free survival (DFS), and overall survival (OS) between HER2-low and HER2-zero phenotypes.

METHODS

We systematically searched the main databases PubMed, Scopus, and Web of Science for articles evaluating women in neoadjuvant therapy expressing HER2-low and HER2-zero. We computed odds ratios (ORs) or hazard ratios (HRs) using DerSimonian and Laird random-effect models for all endpoints, with 95% confidence intervals (CIs). We assessed the heterogeneity using I2 statistics. R, version 4.2.3, was used for statistical analyses.

RESULTS

38 studies totaling 70,104 patients were included. The HER2-low group accounted for 61.3% of patients while HR + status represented 52.4% in the whole research. In 67,839 women, the pCR was analyzed, which in the overall cohort analysis favored the HER2-zero group (OR 0.84; 95% CI 0.78-0.90; p = 0.000005; I2 = 15%). Subgroup analyses for triple-negative breast cancer (TNBC) and HR + patients also favored HER2-zero expression, with an OR of 0.91 (95% CI 0.83-1.0; p < 0.041; I2 = 12%) and 0.75 (95% CI 0.70-0.81; p < 0.000001; I2 = 0%), respectively. In the multivariate analysis across all patients, both DFS and OS outcomes were significantly favorable for the HER2-low expression group, with HR 0.8317 (95% CI 0.7036-0.9832; p = 0.031) for DFS and HR 0.806 (95% CI 0.663-0.979; p = 0.03) for OS.

CONCLUSION

Based on our findings, HER2-zero status is associated with a significantly higher pathological complete response (pCR) rate compared to HER2-low in early-stage breast cancer, and other survival outcomes. These results suggest that HER2-zero should be considered a prognostic factor in early-stage breast cancer and taken into account in neoadjuvant treatment planning and future clinical research.

Activity and Efficacy of Neoadjuvant Chemotherapy in Luminal-HER2 Negative Early Breast Cancer According to HER2 Score (Low vs. Score 0): A Retrospective Study

BACKGROUND

The predictive and prognostic role of HER2 status in patients with luminal-HER2 negative early breast cancer (BC) undergoing neoadjuvant chemotherapy is unclear. A retrospective analysis evaluating the correlation between HER2 status (low vs. score 0) and pCR/IDFS was conducted.

METHODS

Patients with BC undergoing neoadjuvant chemotherapy and surgery were included. HER2 low BC was defined as IHC 1+ or 2+ with negative FISH. Logistic regression model and Cox proportional hazard model were adopted to investigate the independent role of HER2 status and outcomes of interest (pCR, CPS-EG and IDFS).

RESULTS

About 566 patients were included: 60% were HER2 low and 40% were HER2 0. pCR was achieved in 13.2% of HER2 low versus 17.7% of HER2 0 (P = .15). There was no correlation between baseline HER2 status and CPS-EG score (P = .18). A trend toward improved IDFS for HER2 low BC was observed (P = .07). The relapse rate of the HER2 0 cohort peaked at 12 months after surgery, similar to the HER2 low cohort, which showed an additional peak at 36 months after surgery.

CONCLUSIONS

Among Luminal-HER2 negative early BCs, our results do not support a clear predictive and prognostic effect of HER2 status, although a trend of worse pCR and better survival for HER2 low BCs cannot be ruled out.

Clinicopathological characteristics and long-term prognosis of triple-negative breast cancer patients with HER2-Low expression: a retrospective propensity score-matched cohort study

PURPOSE

The objective of the current research was to assess the clinicopathological characteristics and long-term prognosis of triple-negative breast cancer (TNBC) patients with human epidermal growth factor receptor 2 (HER2)-low status following breast surgery.

METHODS

A total of 202 TNBC patients treated at Qingdao Central Hospital from January 2010 to December 2019 were included, comprising 71 HER2-low and 131 HER2-zero patients. Propensity score matching (PSM) was applied to minimize differences between the cohorts.

RESULTS

HER2-low TNBC patients had lower histological grade, lower Ki-67 expression levels, and a higher prevalence of hypertension compared to HER2-zero TNBC patients. Before and after PSM, the HER2-low group consistently exhibited a lower recurrence rate and longer RFS compared to HER2-zero TNBC patients. HER2-low status was validated as an independent low-risk factor for RFS both pre-PSM (HR 0.354, 95% CI 0.178-0.706, p = 0.003) and post-PSM (HR 0.405, 95% CI 0.185-0.886, p = 0.024). No statistically significant differences in mortality rate and OS were observed, both before and after PSM.

CONCLUSIONS

HER2-low and HER2-zero TNBC patients show significant clinicopathological differences. Compared to HER2-zero, HER2-low status is linked to better long-term prognosis and serves as an independent low-risk factor for RFS in TNBC patients.

Clinical outcomes of early-stage triple-negative breast cancer after neoadjuvant chemotherapy according to HER2-low status☆

BACKGROUND

The impact of human epidermal growth factor receptor 2 (HER2) expression determined by immunohistochemistry (IHC) on outcomes in early-stage triple-negative breast cancer (eTNBC) is unclear. Using a large, multi-institutional cohort, we evaluated outcomes by HER2 IHC status in patients with eTNBC who received neoadjuvant therapy (NAT).

PATIENTS AND METHODS

Patients with stage I-III TNBC who received NAT and underwent surgery from January 2016 to June 2019 were identified from three databases. HER2 expression was defined as low (IHC1+ or 2+/FISH not amplified) or HER2 IHC score 0 by local testing at diagnosis. Pathological complete response (pCR) rates were compared using logistic regression adjusted for multiple factors. Survival outcomes were estimated using Kaplan-Meier and Cox proportional hazards models.

RESULTS

Among 977 consecutive patients, 388 (39.7%) had HER2-low and 589 (60.3%) had HER2 IHC score 0 tumors. Median age at eTNBC diagnosis was 50.3 years (range 21.0-83.4 years). At baseline, clinical nodal positivity rate was significantly higher in HER2-low (55.0%) versus HER2 IHC score 0 tumors (46.6%) (P = 0.011); pCR rates were similar (32.0% versus 32.6%; adjusted P = 0.924). At a median follow-up of 3.5 years, recurrence-free survival (RFS) did not vary significantly between HER2-low versus HER2 IHC score 0 among patients with pCR (adjusted P = 0.368) or residual disease (RD) after NAT (adjusted P = 0.573). Distant RFS and overall survival (OS) did not differ by HER2 category for patients with pCR [distant RFS (DRFS), adjusted P = 0.509; OS, adjusted P = 0.514] or RD (DRFS, adjusted P = 0.812; OS, P = 0.285). Discordance of tumor HER2 status was seen in 31.1% of HER2 IHC score 0 cases, with HER2 expression observed post-treatment; 34.8% of HER2-low cases showed discordance, with absent HER2 expression in RD.

CONCLUSIONS

In this large cohort of patients with eTNBC treated with NAT, HER2-low status was not associated with pCR or survival after adjusting for clinical factors. The discordance in HER2 IHC pre- and post-NAT likely reflects challenges in HER2 quantification and heterogeneity.

HER2-low non-metastatic breast cancer in Qatar-a nationwide retrospective cohort study to evaluate the response to neoadjuvant chemotherapy: a real-world analysis

Globally, breast cancer is the most prevalent cancer and one of the leading causes of cancer-related death among women. HER2-low breast cancer represents a recently identified molecular category within breast cancer characterized by tumors displaying only slight overexpression of HER2 or lacking gene amplification. To illustrate, HER2-low tumors typically have an IHC (immune histochemistry) score of 1+ or 2+ with negative amplification. Nonetheless, recent findings indicate that even a slight amplification of HER2 could notably influence both therapeutic responses and prognostic outcomes. Our study aims to unveil the impact of HER2-low expression on the response to anthracycline and taxane-based neoadjuvant chemotherapy (NACT) in comparison to the HER2-negative group in non-metastatic breast cancer. This is a retrospective cohort study. All patients' profiles with non-metastatic, HER2-low, and HER2-negative breast cancers who were administered neo-adjuvant chemotherapy and had surgery performed within the period spanning from 1 January 2018 to 30 August 2022 were enrolled. HER2-positive breast cancer patients were excluded. The evaluation of patients' responses was conducted through the examination of surgical pathology reports to compare the two study groups (HER2-low and HER2-negative). The primary objective was evaluating the response to NACT comparing the objective response rate (ORR) in each of the two groups of HER2-low and HER2-negative patients. The total number of patients included was 262 patients; the majority were HER2-low 89% (233/262) vs. 11% (29/262) HER2-negative. An ORR (complete and partial response) to NACT was shown in 71% (185/262) of all patients. The ORR was similar in both groups, 70% (164/233) in the HER2-low group vs. 73% (21/29) in the HER2-negative group, with a statistical difference, OR: 1 (95% CI: 0.8-1), p-value 0.8. Similarly, the pathological complete response (pCR) rate was the same in both study groups at 14%, OR: 0.7 (95% CI: 0.2-3), p-value: 0.6. Interestingly, patients with hormone-positive tumors across both study groups had a higher response rate compared to hormone-negative patients. In the HER2-low cohort, the ORR was higher in patients with hormone-positive tumors in comparison with those with hormone-negative tumors [73% vs. 27%, OR: 0.8 (95% CI:0.8-1), p-value: 0.001]. Comparatively, in the HER2-negative cohort, ORR was also higher in patients with hormone-positive tumors compared to hormone-negative tumors [52% vs. 48%, OR: 2 (95% CI: 1-5), p-value: 0.05]. Subsequently, the ORR of all hormone-positive tumors with a positive outcome (CR or PR) was assessed categorizing the patients based on their HER2 expression. Concerning patients who expressed partial response (N = 115), a statistically significant difference was observed in HER2- low hormone-positive tumors as opposed to HER2-negative hormone-positive tumors [90% vs. 10%, OR: 0.7 (95% CI: 0.5-0.9), p-value: 0.001]. Remarkably, all patients with complete responses were from the HER2-low cohort. Our findings demonstrated a significant influence of HER2-low expression on the response to neoadjuvant chemotherapy among patients with hormone-positive HER2-low breast cancer within the studied cohort. Further studies are needed to evaluate the influence of hormonal expression on the response rate to NACT in the HER2-low patients in our population.

The prognostic impact of Her2 status in early triple negative breast cancer: a Turkish Oncology Group (TOG) study

The studies evaluating the impact of Her2 levels in neoadjuvant setting have conflicting data. The aim of the study was to evaluate the prognostic impact of Her2 status in early triple negative breast cancer(TNBC). In the study TNBC patients who were treated with neoadjuvant chemotherapy (NAC) and surgery were analyzed retrospectively. The primary aim of the study was to analyze the impact of Her2 status(Her2-0 and Her2-low) on pathological complete response (pCR). The secondary objectives were disease free survival (DFS) and overall survival (OS). 620 female triple negative breast cancer patients were evaluated. 427 patients (68.9%) had Her2-0 and 193(31.1%) had her2-low pathology. The pCR rates were similar between Her2-0 and Her2-low patients (33.0% vs. 27.5%, p = 0.098). Although Her2-0 group has better DFS (106 vs. 50 months, p = 0.002), in multivariate analysis it had a HR of 0.74 (p = 0.06). In addition, OS was similar (131 vs. 105 months, p = 0.13) with a HR of 0.88 (p = 0.61). In multivariate analysis; presence of LVI (HR:2.2 (95% CI 1.1-3.5) p = 0.001), Clinical stage T1/T2 (HR:0.39 (95% CI 0.2-0.6) p < 0.001) and lymph node negativity (HR:0.35 (95% CI 0.1-0.9) p = 0.03) were independent factors for OS. Although there were pathological and clinical differences, the pCR, DFS and OS were similar between Her2-0 and Her2-low TNBC patients. The importance of Her2 status of TNBC in neoadjuvant setting should be further studied.

Comparison of the Pathological Complete Response Rate and Survival Between HER2-Low and HER2-Zero Breast Cancer in Neoadjuvant Chemotherapy Setting: A Systematic Review and Meta-Analysis

Although HER2-low breast cancer (BC) constitutes almost 50% of all BC types, its impact on the pathological complete response (pCR) rate and survival in early BC is uncertain. As a result, a systematic review was conducted to compare the pCR rate and survival of HER2-low and HER2-zero BC in the neoadjuvant chemotherapy (NACT) setting. Two reviewers independently performed literature searches using EMBASE, PubMed, and Cochrane Libraries internet databases up to June 2023. Finally, 29 studies with 178,294 patients were included. HER2-low BC had a considerably lower pCR rate compared to HER2-zero BC in the entire population (Risk Ratio [RR] = 0.68, P < .001) and in the hormone receptor (HR)-positive subgroup (RR = 0.73, P = .009), but not in the HR-negative subgroup (RR = 0.99, P = .755). Furthermore, patients with HER2-low BC exhibited prolonged disease-free survival (DFS) and overall survival (OS) compared to those with HER2-zero BC, observed in both the entire cohort (DFS: P = .004; OS: P = .008) and the HR-negative subgroup (DFS: P = .009; OS: P < .001). In the HR-positive population, OS was superior in HER2-low BC patients (P < .001), whereas no significant differences in DFS were observed (P = .064). Our findings imply that the pCR rate and prognosis of HER2-low BC are distinguished from those of HER2-zero BC in early BC treated with NACT, which contributes to a better knowledge of the BC subgroup.

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.

Insights Into the Emerging Entity of HER2-Low Breast Cancer

Human epidermal growth factor receptor 2 (HER2)-low breast cancer (BC) is a subtype of BC that has been recently recognized as a separate clinical entity with distinct clinical and molecular characteristics. It is defined by a low level of HER2 protein expression, which distinguishes it from other more aggressive BC subtypes. Early studies suggest that it may have a more favorable prognosis than HER2-positive BC, as it is less likely to spread to other parts of the body and may be more responsive to standard BC treatments such as chemotherapy, radiation therapy, and hormone therapy. Given the relative new emergence of HER2-low BC, there is still much to be learned about this subtype; ongoing research is focused on identifying the underlying genetic mutations that contribute to HER2-low BC as well as developing targeted therapies that can improve outcomes for patients with this disease. This review is aimed at summarizing the current clinical knowledge on HER2-low BC, with the aim of creating a better understanding of this entity and paving the way for potential interventions and a new standard of care.

Neoadjuvant chemotherapy efficacy and prognosis in HER2-low and HER2-zero breast cancer patients by HR status: a retrospective study in China

Background

The promising efficacy of novel anti-HER2 antibody-drug conjugates (ADC) in HER2-low breast cancer has made HER2-low a research hotspot. However, controversy remains regarding the neoadjuvant chemotherapy (NAC) efficacy, prognosis, and the relationship with hormone receptor (HR) status of HER2-low.

Methods

A retrospective analysis was conducted on 975 patients with HER2-negative breast cancer undergoing NAC at Tianjin Medical University Cancer Institute and Hospital, evaluating pathological complete response (pCR) rate and prognosis between HER2-low and HER2-zero in the overall cohort and subgroups.

Results

Overall, 579 (59.4%) and 396 (40.6%) patients were HER2-low and HER2-zero disease, respectively. Compared with HER2-zero, the HER2-low cohort consists of more postmenopausal patients, with lower histological grade and higher HR positivity. In the HR-positive subgroup, HER2-low cases remain to exhibit lower histological grade, while in the HR-negative subgroup, they show higher grade. The HER2-low group had lower pCR rates than the HER2-zero group (16.4% vs. 24.0%). In the HR-positive subgroup, HER2-low consistently showed lower pCR rate (8.1% vs. 15.5%), and served as an independent suppressive factor for the pCR rate. However, no significant difference was observed in the pCR rates between HER2-low and HER2-zero in the HR-negative breast cancer. In the entire cohort and in stratified subgroups based on HR and pCR statuses, no difference in disease-free survival were observed between HER2-low and HER2-zero.

Conclusions

In the Chinese population, HER2-low breast cancer exhibits distinct characteristics and efficacy of NAC in different HR subgroups. Its reduced pCR rate in HR-positive subgroup is particularly important for clinical decisions. However, HER2-low is not a reliable factor for assessing long-term survival outcomes.

Molecular and Clinical Portrait of HER2-low Invasive Lobular Carcinomas

Invasive lobular carcinomas (ILCs) have a low frequency of ERBB2 amplification, therefore restricting the use of conventional anti-HER2 therapies for this histologic special type. Conversely, ILCs with low HER2 overexpression may represent a broader target for the use of emerging antibody drug conjugate therapies targeting HER2, since these treatments have proven effective in HER2-low breast cancers. Very scarce data about HER2-low ILCs have been so far published, although these tumors could have different prevalence and histomolecular specificities compared with invasive breast carcinoma of no special type (IBC-NST). Our aims in that context were to decipher the clinicopathological and molecular features of a large series of HER2-low ILCs. Comparative evaluation of HER2-low prevalence was done based on a retrospective series of 7970 patients from Institut Curie, with either primary invasive lobular (N = 1103) or no special type (N = 6867) invasive carcinoma. Clinicopathological and molecular analyses of HER2-zero, HER2-low, and HER2-positive ILCs were performed on a subgroup of 251 patients who underwent surgery for a primary ILC between 2005 and 2008. The mutational profile of these 251 cases was determined from RNAseq data. Compared with HER2-negative IBC-NSTs, the HER2-negative ILCs were found to display a higher frequency of HER2-zero cases (59.4% vs 53.7%) and a lower frequency of HER2-low (40.6% vs 46.3%) (P < .001). Clinicopathological features associated with HER2-low status (vs HER2-zero) in ILC were older age, postmenopausal status, nonclassic ILC histological types, higher grade, proliferation, and estrogen receptor expression levels. Survival curve analysis showed a significantly lower risk of local recurrence for HER2-low (vs HER2-zero) ILCs, but no association was found between HER2 status and either breast cancer-specific survival or distant metastasis-free interval. ERBB3 was the unique mutated gene exclusively associated with HER2-low ILCs yet being mutated at a low frequency (7.1%) (false discovery rate < 0.05). In conclusion, HER2-low ILCs exhibit their own particularities, both on clinical-pathological and molecular levels. Our findings call for larger multicenter validation studies.

Association between human epidermal growth factor receptor 2 status, namely low and zero expression, and prognosis in hormone receptor-positive breast cancer: a single-center retrospective study

Background

The recently developed anti-human epidermal growth factor receptor 2 (HER2) therapy has substantially improved the prognosis of HER2-positive breast cancer. The DESTINY-Breast04 trial results showed that trastuzumab deruxtecan (T-DXd) significantly prolonged the survival of patients with HER2-low breast cancer, thus presenting a paradigm shift in anti-HER2 therapy. This may facilitate a change in the treatment strategy for HER2-low breast cancer. However, the implication of HER2-low in hormone receptor (HR)-positive breast cancer is unclear. In this retrospective study, we aimed to reveal the association between HER2 status, namely HER2-low and HER2-zero, and prognosis in HR-positive breast cancer.

Methods

We collected the data of 247 patients with estrogen receptor (ER)-positive/HER2-negative breast cancer (159 with HER2-low and 88 with HER2-zero breast cancer) who underwent surgery. Patients were divided into HER2-low and HER2-zero groups. Univariate analysis was performed to evaluate the baseline characteristics using the Wilcoxon rank sum test and Fisher's exact test. Survival analysis of the HER2-low and HER2-zero groups was performed using the Kaplan-Meier method.

Results

The median observation period was 2,706 days, and the median period until recurrence was 1,380 days; 25 patients (10%) had recurrences. Age (P=0.004) and menopausal status (P=0.04) were significant variables in the univariate analysis of baseline characteristics. In the subgroup analysis of luminal A- and B-like breast cancers, there was a significant difference in overall survival (OS) only in patients with luminal A-like breast cancer, but relapse-free survival (RFS) of the HER2-low luminal B-like cancer subgroups tended to be relatively short.

Conclusions

We inferred that the HER2-low and HER2-zero statuses do not affect the RFS and OS of patients with ER-positive breast cancer. The prognostic significance of HER2-low or HER2-zero status in luminal A- and B-like breast cancers might differ, and a new treatment strategy is required for the HER2-low subgroup.

Survival outcomes in HER2-low versus HER2-zero breast cancer after neoadjuvant chemotherapy: a meta-analysis

BACKGROUND

The survival outcomes in HER2-low versus HER2-zero breast cancer (BC) after neoadjuvant chemotherapy (NACT) remain unclear. The meta-analysis was conducted to summarize current evidence about the survival outcomes in HER2-low versus HER2-zero BC.

METHODS

We conducted a systematic search in PubMed and EMBASE databases to identify relevant studies.

RESULTS

A total of 14 studies with 53,714 patients were included. Overall, 34,037 patients (63.37%) were HER2-low, and 19,677 patients (36.63%) were HER2-zero. Patients with HER2-low tumors had a significantly lower pathological complete response (pCR) rate than patients with HER2-zero tumors, regardless of the hormone receptor status. Compared with HER2-zero breast cancer, the overall survival (OS) and disease-free survival (DFS) of HER2-low BC were longer in the overall cohort (HR = 0.72; 95% CI = 0.61-0.85; P < 0.0001; HR = 0.83; 95% CI = 0.75-0.92; P = 0.0002); however, no differences were observed in terms of OS and DFS between HER2-low and HER2-zero BC in the HR-negative group. In the HR-positive group, HER2-low status had no significant impact on OS, while significantly associated with increased DFS (HR = 0.85; 95% CI = 0.76-0.96; P = 0.007).

CONCLUSION

These results suggest that although HER2-low BC has a poor response to NACT, it is correlated with favorable OS and DFS after NACT in the overall cohort as well as longer DFS in the HR-positive group.

Open questions, current challenges, and future perspectives in targeting human epidermal growth factor receptor 2-low breast cancer

Approximately 60% of traditionally defined human epidermal growth factor receptor 2 (HER2)-negative breast cancers express low levels of HER2 [HER2-low; defined as immunohistochemistry (IHC) 1+ or IHC 2+/in situ hybridization (ISH)-]. HER2-low breast cancers encompass a large percentage of both hormone receptor-positive (up to 85%) and triple-negative (up to 63%) breast cancers. The DESTINY-Breast04 trial established that HER2-low tumors are targetable, leading to the approval of trastuzumab deruxtecan (T-DXd) as the first HER2-directed therapy for the treatment of HER2-low breast cancer in the United States and Europe. This change in the clinical landscape results in a number of questions and challenges-including those related to HER2 assessment and patient identification-and highlights the need for careful assessment of HER2 expression to identify patients eligible for T-DXd. This review provides context for understanding how to identify patients with HER2-low breast cancer with respect to sample types, scoring and reporting HER2 status, and testing methods and assays. It also discusses management of important T-DXd-related adverse events. Available evidence supports the efficacy of T-DXd in patients with any history of IHC 1+ or IHC 2+/ISH- scores; however, future research may further refine the population who could benefit from T-DXd or other HER2-directed therapies and identify novel methods for patient identification. Because HER2 expression can change with disease progression or treatment, and variability exists in scoring and interpretation of HER2 status, careful re-evaluation in certain scenarios may help to identify more patients who may benefit from T-DXd.

The Modified Neo-Bioscore System for Staging Breast Cancer Treated with Neoadjuvant Therapy Based on Prognostic Significance of HER2-Low Expression

Background: Recently, the classification of HER2 status evolves from binary to ternary, and HER2-low expression may exhibit prognostic significance. We aimed to investigate whether HER2-low tumor is distinct from HER2-zero or HER2-positive tumors, and then to develop a modified staging system (mNeo-Bioscore) that incorporates HER2-low status into Neo-Bioscore. Patients and Methods: This cohort study was conducted using data from the prospective database on breast cancer patients between January 2014 and February 2019. Results: Among 259 patients enrolled in the study, the HER2-low tumor exhibited significantly lower histological grade, pathological staging and Ki-67 level than the other two groups. HER2-low patients and HER2-positive patients receiving concurrent HER2-directed therapy may have similar LRFS (p = 0.531) and OS (p = 0.853), while HER2-zero peers may have significantly worse LRFS (p = 0.006) and OS (p = 0.017). In particular, a similar trend was also found in the patients without pathological complete response after surgery. Incorporation of HER2-low status made improvement in fit: 5-year OS rate estimates ranged from 33.33% to 100% for mNeo-Bioscore vs 61.36% to 100% for Neo-Bioscore. Conclusions: This study demonstrated that HER2-low tumor may exhibit prognostic significance. The innovative mNeo-Bioscore, based on a new classification of HER2 status, may serve as a prognostic staging system superior to Neo-Bioscore.

Clinicopathological characteristics and value of HER2-low expression evolution in breast cancer receiving neoadjuvant chemotherapy

OBJECTIVE

The present study aimed to evaluate the clinicopathological characteristics and value of HER2-low expression evolution in breast cancer receiving neoadjuvant chemotherapy (NAC).

METHODS

Patients with HER2 negative breast cancer receiving NAC from January 2017 to December 2020 were enrolled in this study. The clinicopathological characteristics, response to NAC, evolution of HER2 and prognostic value were retrospectively analyzed.

RESULTS

410 patients were included. The proportion of HR positive disease in HER2-low cases was higher than in HER2-zero population (75.8 % vs. 65.8 %, P = 0.040). No statistical significant difference in pCR rate was observed between HER2-low and HER2-zero patients (33.8 % vs. 39.3 %, P = 0.290) when pCR was defined as ypTis/0ypN0. Exploratory analysis revealed that the pCR rate of HER2-low cases was significantly lower than HER2-zero patients in the entire population (19.8 % vs. 33.3 %, P = 0.004) and HR positive population (12.6 % vs. 29.9 %, P = 0.001) when pCR was defined as ypT0ypN0. The evolution rate of HER2 expression after NAC was 31.0 % in HER2-zero patients and 24.7 % in HER2-low patients. Compared with patients with HR positive disease, patients with TNBC had higher evolution rate of HER2 expression after NAC (37.7 % vs. 23.6 %). Significant association was observed between HER2 evolution with histology type and Ki-67 index in HER2-zero patients and with lymph node involvement, HR status and Ki-67 index in HER2-low patients. Prognostic impact of HER2 evolution was not observed.

CONCLUSIONS

HR positive and HR negative HER2-low breast cancer exhibit different clinicopathological features, response to NAC and HER2 evolution after treatment.

Racial/Ethnic Differences in Pathologic Complete Response to Neoadjuvant Chemotherapy and Survival Among Early-Stage, Erb-B2 Receptor Tyrosine Kinase 2-Low Breast Cancer Patients

Racial/ethnic differences in pathologic complete response (pCR), and in overall survival (OS) by pCR status, among early-stage, erb-b2 receptor tyrosine kinase 2 (ERBB2)-low breast cancer patients after neoadjuvant chemotherapy (NACT) are unknown. Data were from the 2010-2020 National Cancer Database that included Asian/Pacific Islander (API), American Indian/Alaska Native/Other (AIANO), Black, Hispanic, and White patients. pCR and OS were modeled using logistic regression and Cox regression, respectively. Of 25,577 patients, Black patients achieved a 17.4% pCR rate, Hispanic 16.0%, White 14.7%, API 13.5%, and AIANO 10.9%. AIANO patients had lower odds of pCR than White patients (adjusted odds ratio, 0.66; 95% confidence interval [CI], 0.48-0.91). Among patients without pCR, API (adjusted hazard ratio [aHR], 0.62; 95% CI, 0.51-0.76) and Hispanic (aHR, 0.77; 95% CI, 0.67-0.89) patients had lower mortality risks than White patients. Among patients with pCR, similar OS rates were observed between Hispanic (aHR, 1.08; 95% CI, 0.66-1.78), Black (aHR, 0.77; 95% CI, 0.55-1.09), API (aHR, 0.41; 95% CI, 0.15-1.12), or AIANO (aHR, 0.35; 95% CI, 0.05-2.50) and White patients. Post-NACT pCR rates were similar across racial/ethnic groups of early-stage, ERBB2-low breast cancer patients. Among patients without pCR, API and Hispanic patients had better OS; among patients with pCR, there was no differential OS by race/ethnicity. Our findings suggest the need for longitudinal studies of OS differences in this patient population.

Impact of HER2-low status for patients with early-stage breast cancer and non-pCR after neoadjuvant chemotherapy: a National Cancer Database Analysis

PURPOSE

To investigate potential differences in pathological complete response (pCR) rates and overall survival (OS) between HER2-low and HER2-zero patients with early-stage hormone receptor (HR)-positive and triple-negative breast cancer (TNBC), in the neoadjuvant chemotherapy setting.

METHODS

We identified early-stage invasive HER2-negative BC patients who received neoadjuvant chemotherapy diagnosed between 2010 and 2018 in the National Cancer Database. HER2-low was defined by immunohistochemistry (IHC) 1+ or 2+ with negative in situ hybridization, and HER2-zero by IHC0. All the methods were applied separately in the HR-positive and TNBC cohorts. Logistic regression was used to estimate the association of HER2 status with pCR (i.e. ypT0/Tis and ypN0). Kaplan-Meier method and Cox proportional hazards model were applied to estimate the association of HER2 status with OS. Inverse probability weighting and/or multivariable regression were applied to all analyses.

RESULTS

For HR-positive patients, 70.9% (n = 17,934) were HER2-low, whereas 51.1% (n = 10,238) of TNBC patients were HER2-low. For both HR-positive and TNBC cohorts, HER2-low status was significantly associated with lower pCR rates [HR-positive: 5.0% vs. 6.7%; weighted odds ratio (OR) = 0.81 (95% CI: 0.72-0.91), p < 0.001; TNBC: 21.6% vs. 24.4%; weighted OR = 0.91 (95% CI: 0.85-0.98), p = 0.007] and improved OS [HR-positive: weighted hazard ratio = 0.85 (95% CI: 0.79-0.91), p < 0.001; TNBC: weighted hazard ratio = 0.91 (95% CI: 0.86-0.96), p < 0.001]. HER2-low status was associated with favorable OS among patients not achieving pCR [HR-positive: adjusted hazard ratio = 0.83 (95% CI: 0.77-0.89), p < 0.001; TNBC: adjusted hazard ratio = 0.88 (95% CI 0.83-0.94), p < 0.001], while no significant difference in OS was observed in patients who achieved pCR [HR-positive: adjusted hazard ratio = 1.00 (95% CI: 0.61-1.63), p > 0.99; TNBC: adjusted hazard ratio = 1.11 (95% CI: 0.85-1.45), p = 0.44].

CONCLUSION

In both early-stage HR-positive and TNBC patients, HER2-low status was associated with lower pCR rates. HER2-zero status might be considered an adverse prognostic factor for OS in patients not achieving pCR.

Pathological complete response rate and clinical outcome after neoadjuvant therapy of HER2-low breast cancer: A National Cancer Database Analysis

BACKGROUND

The interest in breast cancer with low HER2 expression as a distinct subtype is increasing. We aimed to explore the differences between HER2-low and HER2-zero breast cancer in their prognosis and rate of pathological complete response (pCR) after neoadjuvant therapy.

METHODS

The National Cancer Database (NCDB) was used to select patients with breast cancer who received neoadjuvant therapy from 2004 to 2017. Logistic regression model was constructed for analysis of pCR. Cox proportional hazards regression model and Kaplan-Meier method were used for survival analysis.

RESULTS

A total of 41500 breast cancer patients were included, among which 14814 (35.7%) had HER2-zero tumors and 26686 (64.3%) had HER2-low. HER2-low tumors were more commonly HR-positive in comparison with HER2-zero (66.3% versus 47.1%, P < 0.001). A lower rate of pCR was observed in HER2-low tumors than in HER2-zero tumors after neoadjuvant therapy in the total cohort (OR = 0.90; 95% CI [0.86-0.95]; P < 0.001) and in the subset of HR-positive (OR = 0.87; 95% CI [0.81-0.94]; P < 0.001). Patients with HER2-low tumors had a significantly superior survival than those with HER2-zero tumors (HR = 0.90; 95% CI [0.86-0.94]; P < 0.001), regardless of the HR status. Additionally, a marginal survival difference was also observed between HER2 IHC1+ and HER2 IHC2+/ISH-negative (HR = 0.91; 95% CI [0.85-0.97]; P = 0.003) cohorts.

CONCLUSION

HER2-low tumors are a clinically relevant breast cancer subtype that is distinct from HER2-zero tumors. These findings may provide clues to appropriate therapeutic strategies for this subtype in the future.

Pathologic complete response and survival in HER2-low and HER2-zero early breast cancer treated with neoadjuvant chemotherapy

BACKGROUND

Breast cancers without HER2 amplification but still expressing this membrane protein constitute a new entity called HER2-low tumors. It is important to characterize them in terms of sensitivity to treatment and prognosis.

PATIENTS AND METHODS

To investigate chemosensitivity and long-term prognosis of HER2-low early breast cancer (eBC), compared to HER2-0 tumors, we retrospectively retrieved clinicopathological characteristics, response to treatment, and survival data from 511 patients treated for eBC with neoadjuvant chemotherapy (NAC) in a French cancer center between 2007 and 2018. Factors associated with the achievement of pathologic complete response (pCR) and survival were studied among hormone receptor positive (HR+) and negative (HR-) eBC.

RESULTS

A total of 280 HR+ (61% HER2-low), and 231 HR- (28% HER2-low) eBC were included. We found classical clinicopathological factors usually associated with chemosensitivity and prognosis, in both HR+ and HR- eBC. By uni- and multivariable analysis, HER2 status (low vs 0) was not independently associated with pCR, either in HR+ or HR- eBC. Relapse free (RFS) and overall survival (OS) were not significantly different between HER2-low and HER2-0 among HR+ tumors. In contrast, among HR- negative tumors, RFS and OS were slightly better in HER2-0 eBC by univariable but not by multivariable analysis.

CONCLUSIONS

In eBC patients treated with NAC, taking into account HR expression subtype and other current clinicopathological features, HER2-low tumors did not appear to have different chemosensitivity or prognosis, compared to their HER2-0 counterparts.

HER2-Low Breast Cancer: Current Landscape and Future Prospects

More than 50% of breast cancers are currently defined as "Human epidermal growth factor receptor 2 (HER2) low breast cancer (BC)", with HER2 immunohistochemistry (IHC) scores of +1 or +2 with a negative fluorescence in situ hybridization (FISH) test. In most studies that compared the clinical and biological characteristics of HER2-low BC with HER2-negative BC, HER2-low was not associated with unique clinical and molecular characteristics, and it seems that the importance of HER2 in these tumors is being a docking site for the antibody portion of antibody drug conjugates (ADCs). Current pathological methods may underestimate the proportion of BCs that express low levels of HER2 due to analytical limitations and tumor heterogeneity. In this review we summarize and contextualize the most recent literature on HER2-low breast cancers, including clinical and translational studies We also review the challenges of assessing low HER2 expression in BC and discuss the current and future therapeutic landscape for these tumors.

The Effect of HER2-Low Status on Pathological Complete Response and Survival in Triple-Negative Breast Cancer: A Systemic Review and Meta-Analysis

This meta-analysis conducted a comprehensive analysis of research investigating the correlation between HER2 expression levels and treatment outcomes in early-stage triple-negative breast cancer (TNBC) patients. We systematically searched major databases for studies published up to January 01, 2023. The data from various studies examined the relationship between HER2-zero and HER2-low tumors in terms of pathological complete response (pCR) rates, disease-free survival (DFS), and overall survival (OS) outcomes. The odds ratio (OR) and 95% confidence interval (CI) by the number of events were calculated using the Mantel-Haenszel method to analyze pCR. The hazard ratio and 95% CI were calculated using the inverse variance method for DFS and OS. In all comparisons, I2 was 0% and no heterogeneity was detected. A total of 12 retrospective studies involving 4094 patients were included. Thirty-six percent of the patients were in the HER2-low group. All 12 studies were included in the pooled analysis for pCR, and there was no difference between HER2-zero and HER2-low (40% vs. 38%, respectively; pooled OR:1.01 95% CI 0.88-1.16; I2: 0%). Four studies were included in the pooled analysis for DFS and 3 in the OS analysis. DFS and OS were significantly better in the HER2-low group (pooled hazard ratio: 0.67 for DFS, 0.64 for OS). There was no difference between HER2-low and HER2-zero in terms of pCR in early-stage TNBC. However, HER2-low was found to be associated with prolonged DFS and OS. PROSPERO REGISTRATION NUMBER: CRD42023391002.

A Novel NanoMIP-SPR Sensor for the Point-of-Care Diagnosis of Breast Cancer

Simple, fast, selective, and reliable detection of human epidermal growth factor receptor 2 (HER2) is of utmost importance in the early diagnosis of breast cancer to prevent its high prevalence and mortality. Molecularly imprinted polymers (MIPs), also known as artificial antibodies, have recently been used as a specific tool in cancer diagnosis and therapy. In this study, a miniaturized surface plasmon resonance (SPR)-based sensor was developed using epitope-mediated HER2-nanoMIPs. The nanoMIP receptors were characterized using dynamic light scattering (DLS), zeta potential, Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and fluorescent microscopy. The average size of the nanoMIPs was determined to be 67.5 ± 12.5 nm. The proposed novel SPR sensor provided superior selectivity to HER2 with a detection limit (LOD) of 11.6 pg mL^-1 in human serum. The high specificity of the sensor was confirmed by cross-reactivity studies using P53, human serum albumin (HSA), transferrin, and glucose. The sensor preparation steps were successfully characterized by employing cyclic and square wave voltammetry. The nanoMIP-SPR sensor demonstrates great potential for use in the early diagnosis of breast cancer as a robust tool with high sensitivity, selectivity, and specificity.

Comparison of the pCR Rate and DFS Among Breast Cancer Patients with Different Hormone Receptor and HER2 Statuses

Background

Recent studies have investigated the features of breast cancer (BC) with low human epidermal growth factor receptor 2 (HER2) expression or HER2-0 expression. However, the results were inconsistent. In this study, we investigated the differences in the pathological complete response (pCR) rate and disease-free survival (DFS) between HER2-low and HER2-0 BC patients and between subgroups.

Methods

HER2-negative BC patients who received neoadjuvant chemotherapy between January 2013 and December 2019 in our hospital were retrospectively reviewed. First, the pCR rate and DFS were compared between HER2-low and HER2-0 patients and among different hormone receptor (HR) and HER2 statuses. Subsequently, DFS was compared between different HER2 status populations with or without pCR. Finally, a Cox regression model was used to identify the prognostic factors.

Results

Overall, 693 patients were selected: 561 were HER2-low, and 132 were HER2-0. Between the two groups, there were significant differences in N stage (P = 0.008) and HR status (P = 0.007). No significant difference in the pCR rate (12.12% vs 14.39%, P = 0.468) or DFS was observed, independent of HR status. HR+/HER2-low patients had a significantly worse pCR rate (P < 0.001) and longer DFS (P < 0.001) than HR-/HER2-low or HER2-0 patients. In addition, a longer DFS was found in HER2-low patients versus HER2-0 patients among those who did not achieve pCR. Cox regression showed that N stage and HR status were prognostic factors in the overall and HER2-low populations, while no prognostic factor was found in the HER2-0 group.

Conclusion

This study suggested that HER2 status is not associated with the pCR rate or DFS. Longer DFS was found only among patients who did not achieve pCR in the HER2-low versus HER2-0 population. We speculated that the interaction of HR and HER2 might have played a crucial role in this process.