Clinicopathologic Factors Associated With Response to Neoadjuvant Anti-HER2-Directed Chemotherapy in HER2-Positive Breast Cancer

In situ HER2 RNA expression as a predictor of pathologic complete response of HER2-positive breast cancer patients receiving neoadjuvant chemotherapy and anti-HER2 targeted treatment

BACKGROUND

Immunohistochemistry (IHC) and in situ hybridization (ISH) remain standard biomarkers for therapeutic decisions in human epidermal growth factor 2 (HER2)-positive breast cancers (BCs); however, they are insufficient to explain the heterogeneous anti-HER2 response.

METHODS

We aimed to investigate the correlation of in situ HER2 RNA expression (isHRE), using RNAscope, with HER2 biomarkers and the impact of isHRE on the pathological complete response (pCR) rates of 278 patients with HER2 IHC/fluorescence ISH (FISH)-positive BC receiving neoadjuvant chemotherapy and anti-HER2 targeted treatment (NCTT).

RESULTS

We validated HER2 RNAscope scoring as a semiquantitative method to determine isHRE and showed a positive correlation between RNAscope scores and pCR rates, with particularly different rates between patients with a score of 5 versus 1-4 BCs (66.7% vs. 15.9%, p < 0.0001). There were higher RNAscope scores and pCR rates in patients with HER2 IHC 3 + versus IHC 2+/FISH + BCs and HER2 RNAscope scores and pCR rates showed similar non-linear positive correlations with HER2 copy numbers and HER2/centromere 17 ratios. Moreover, in each HER2-positive IHC/FISH category, higher pCR rates were observed in patients with RNAscope scores of 5 versus 1-4 BC. Patients achieving pCR had BCs with notably higher HER2 RNAscope scores. Multivariate analysis identified HER2 RNAscope 5 as a strong pCR predictor [odds ratio = 10.865, p < 0.001]. The combined impact of multivariate analysis-defined pCR predictors demonstrated that a higher pCR rate was observed in patients with a score of 5 versus a score of 1-4 BCs regardless of the status of hormone receptor and mono-or dual anti-HER2 blockade.

CONCUSIONS

Our results demonstrated that high isHRE (RNAscope score 5) is a strong pCR predictor in patients with HER2-positive BCs receiving NCTT, highlighting the complementary role of isHRE in stratifying HER2 status in tissue. Such stratification is relevant to anti-HER2 therapeutic efficacy, particularly using the cutoff of score 1-4 versus 5.

The association of PD-L1 expression and CD8-positive T cell infiltration rate with the pathological complete response after neoadjuvant treatment in HER2-positive breast cancer

PURPOSE

Achieving a pathological complete response (pCR) after neoadjuvant therapy in HER2-positive breast cancer patients is the most significant prognostic indicator, suggesting a low risk of recurrence and a survival advantage. This study aims to investigate clinicopathological parameters that can predict the response to neoadjuvant treatment in HER2 + breast cancers and to explore the roles of tumour-infiltrating lymphocytes (TILs), CD8 + T lymphocytes and PD-L1 expression.

METHODS

This single-centre retrospective study was conducted with 85 HER2-positive breast cancer patients who underwent surgery after receiving neoadjuvant therapy between January 2017 and January 2020. Paraffin blocks from these patients were selected for immunohistochemical studies.

RESULTS

A complete pathological response to neoadjuvant treatment was determined in 39 (45.9%) patients. High Ki-67 index (> 30%), moderate to high TIL infiltration, PD-L1 positivity and high CD8 cell count (≥ 25) were significantly associated with pCR in univariate analyses (p: 0.023, 0.025, 0.017 and 0.003, respectively). Multivariate regression analysis identified high Ki-67 index (> 30%) and CD8 cell infiltration as independent predictors for pCR in HER2-positive breast cancer.

CONCLUSIONS

High Ki-67 index, and high CD8 cell count are strong predictors for pCR in HER2-positive breast cancer. Tumours with high Ki-67 index, high TILs and CD8 infiltration may represent a subgroup where standard therapies are adequate. Conversely, those with low TILs and CD8 infiltration may identify a subgroup where use of novel strategies, including those that increase CD8 infiltration could be applied.

Correlation of In Situ HER2 RNA Expression With HER2 Immunohistochemistry and Fluorescence In Situ Hybridization Categories in Breast Cancer

CONTEXT.—

RNA sequencing study has demonstrated that human epidermal growth factor receptor 2 (HER2) RNA levels influence anti-HER2 therapeutic efficacy. However, in situ HER2 RNA expression (isHRE), which evaluates HER2 RNA expression in tissue, has remained unclear in breast cancers (BCs) of various HER2 immunohistochemistry (IHC)/in situ hybridization (ISH) categories.

OBJECTIVE.—

To correlate isHRE with all HER2 IHC/fluorescence ISH (FISH) categories in BC.

DESIGN.—

Formalin-fixed, paraffin-embedded tissue sections from 259 BCs, covering all IHC/FISH categories, were analyzed for isHRE by RNAscope.

RESULTS.—

We validated HER2 RNAscope scoring as a semiquantitative method to evaluate isHRE and demonstrated significantly higher RNAscope scores in IHC 3+ than in IHC 2+ cases, and in IHC 2+ than in IHC 0/1+ cases. Among the 5 IHC 2+/FISH groups, group 1 (G1) cases had the highest scores. The scores in G3 cases were higher than those in G2, but not significantly different from those in G4 and G5. G4 cases had significantly higher scores than those in G2. Higher HER2 copy numbers and HER2:CEP 17 (centromere 17) copy number ratios were significantly correlated with higher isHRE in G1 cases, but not in G2 to G5 cases. RNAscope scores were significantly lower in HER2-negative (IHC 0) than in HER2-low (IHC 2+/FISH- and IHC 1+) BCs but were not different between IHC 0 and 1+ BCs when analyzed separately.

CONCLUSIONS.—

We demonstrate the HER2 RNA expression status among BCs of various HER2 IHC/FISH categories in tissue. Such information may be relevant for anti-HER2 treatment decisions considering the role of HER2 RNA expression in predicting anti-HER2 therapeutic efficacy.

Correlation of HER2 Protein Level With mRNA Level Quantified by RNAscope in Breast Cancer

Trastuzumab deruxtecan (T-DXd) has been approved by the US Food and Drug Administration (FDA) to treat patients with metastatic HER2-positive and HER2-low breast cancer, and clinical trials are examining its efficacy against early-stage breast cancer. Current HER2 immunohistochemical (IHC) assays are suboptimal in evaluating HER2-low breast cancers and identifying which patients would benefit from T-DXd. HER2 expression in 526 breast cancer tissue microarray (TMA) cores was measured using the FDA-approved PATHWAY and HercepTest IHC assays, and the corresponding RNA levels were evaluated by RNAscope. HER2 protein levels by regression analysis using a quantitative immunofluorescence score against cell line arrays with known HER2 protein levels determined by mass spectrometry were available in 48 of the cores. RNAscope was also performed in 32 metastatic biopsies from 23 patients who were subsequently treated with T-DXd, and the results were correlated with response rate. HER2 RNA levels by RNAscope strongly correlated with HER2 protein levels (P < .0001) and with HER2 IHC H-scores from the PATHWAY and HercepTest assays (P < .0001). However, neither protein levels nor RNA levels significantly differed between cases scored 0, ultralow, and 1+ by PATHWAY and HercepTest. The RNA levels were significantly higher (P = .030) in responders (6.4 ± 8.2 dots/cell, n = 12) than those in nonresponders (2.6 ± 2.2, n = 20) to T-DXd. RNAscope is a simple assay that can be objectively quantified and is a promising alternative to current IHC assays in evaluating HER2 expression in breast cancers, especially HER2-low cases, and may identify patients who would benefit from T-DXd.

Low interobserver agreement among subspecialised breast pathologists in evaluating HER2-low breast cancer

AIMS

Metastatic HER2-low breast cancer (HLBC) can be treated by trastuzumab deruxtecan. Assessment of low levels of HER2 protein expression suffers from poor interobserver reproducibility. The aim of the study was to evaluate the interobserver agreement among subspecialised breast pathologists and develop a practical algorithm for assessing HLBC.

METHODS

Six breast pathologists (4 juniors, 2 seniors) evaluated 106 HER2 immunostained slides with 0/1+expression. Two rounds (R1, R2) of ring study were performed before and after training with a modified Ki-67 algorithm, and concordance was assessed.

RESULTS

Agreement with 5% increments increased from substantial to almost perfect (R1: 0.796, R2: 0.804), and remained substantial for three categories (<1% vs 1%-10% vs >10%) (R1: 0.768, R2: 0.764). Seniors and juniors had almost perfect agreement with 5% increments (R1: 0.859 and 0.821, R2: 0.872 and 0.813). For the three categories, agreement remained almost perfect among seniors (R1: 0.837, R2: 0.860) and substantial among juniors (R1: 0.792, R2: 0.768). Binary analysis showed suboptimal agreement, decreasing for both juniors and seniors from substantial (R1: 0.650 and 0.620) to moderate (R2: 0.560 and 0.554) using the 1% cut-off, and increasing from moderate to substantial (R1: 0.478, R2: 0.712) among seniors but remaining moderate (R1: 0.576, R2: 0.465) among juniors using the 10% cut-off. The average scoring time per case was higher (72 vs 92 s).

CONCLUSIONS

Subspecialised breast pathologists have suboptimal agreement for immunohistochemical evaluation of HLBC using the modified Ki-67 methodology. An urgent need remains for a new assay/algorithm to reliably evaluate HLBC.

Neoadjuvant therapy for HER2-positive acantholytic squamous cell breast carcinoma: a case report

HER2-positive acantholytic squamous cell carcinoma (ASCC) of the breast is exceptionally rare, and its clinicopathologic features are poorly understood. The impact of neoadjuvant therapy on HER2-positive breast ASCC is unclear. Here we report on a 58-year-old woman who was diagnosed with HER2-positive ASCC of the right breast, who underwent neoadjuvant treatment with albumin-paclitaxel, carboplatin, and trastuzumab, and surgery. Neoadjuvant therapy was effective, with no recurrence or metastasis after 1.5 years of postoperative follow-up.

Pre- and Post-Neoadjuvant Clinicopathological Parameters Can Help in the Prognosis and the Prediction of Response in HER2+ and Triple Negative Breast Cancer

Neoadjuvant treatment (NAT) is one of the most widely used options for HER2+ and triple negative (TN) early breast cancer (BC). Since around half of the patients treated with NAT do not achieve a pathologically complete response (pCR), biomarkers to predict resistance are urgently needed. The correlation of clinicopathological factors with pCR was studied in 150 patients (HER2 = 81; TN = 69) and pre- and post-NAT differences in tumour biomarkers were compared. Low estrogen receptor (ER) expression, high tumour-infiltrating lymphocytes (TILs) and low cT-stage were associated with pCR in HER2+ tumours (p = 0.022; p = 0.032 and p = 0.005, respectively). Furthermore, ER expression was also associated with residual cancer burden (RCB; p = 0.046) in the HER2+ subtype. Similarly, pre-NAT, low progesterone receptor expression (PR; 1-10%) was associated with higher RCB (p < 0.001) in TN tumours. Only clinical and pathological T-stage (cpT-stage) had prognostic capacity in HER2+ tumours, whereas pre-NAT cpT-stage and post-NAT TILs had this capacity for the prognosis of TN tumours. We conclude that ER and PR expression may help predict response to NAT in HER2 and TN BC and should be taken into account in residual tumours. Also, changes observed in the phenotype after NAT suggest the need to reevaluate biomarkers in surviving residual tumour cells.

Deep learning in digital pathology for personalized treatment plans of cancer patients

Over the past decade, many new cancer treatments have been developed and made available to patients. However, in most cases, these treatments only benefit a specific subgroup of patients, making the selection of treatment for a specific patient an essential but challenging task for oncologists. Although some biomarkers were found to associate with treatment response, manual assessment is time-consuming and subjective. With the rapid developments and expanded implementation of artificial intelligence (AI) in digital pathology, many biomarkers can be quantified automatically from histopathology images. This approach allows for a more efficient and objective assessment of biomarkers, aiding oncologists in formulating personalized treatment plans for cancer patients. This review presents an overview and summary of the recent studies on biomarker quantification and treatment response prediction using hematoxylin-eosin (H&E) stained pathology images. These studies have shown that an AI-based digital pathology approach can be practical and will become increasingly important in improving the selection of cancer treatments for patients.

Artificial intelligence reveals features associated with breast cancer neoadjuvant chemotherapy responses from multi-stain histopathologic images

Advances in computational algorithms and tools have made the prediction of cancer patient outcomes using computational pathology feasible. However, predicting clinical outcomes from pre-treatment histopathologic images remains a challenging task, limited by the poor understanding of tumor immune micro-environments. In this study, an automatic, accurate, comprehensive, interpretable, and reproducible whole slide image (WSI) feature extraction pipeline known as, IMage-based Pathological REgistration and Segmentation Statistics (IMPRESS), is described. We used both H&E and multiplex IHC (PD-L1, CD8+, and CD163+) images, investigated whether artificial intelligence (AI)-based algorithms using automatic feature extraction methods can predict neoadjuvant chemotherapy (NAC) outcomes in HER2-positive (HER2+) and triple-negative breast cancer (TNBC) patients. Features are derived from tumor immune micro-environment and clinical data and used to train machine learning models to accurately predict the response to NAC in breast cancer patients (HER2+ AUC = 0.8975; TNBC AUC = 0.7674). The results demonstrate that this method outperforms the results trained from features that were manually generated by pathologists. The developed image features and algorithms were further externally validated by independent cohorts, yielding encouraging results, especially for the HER2+ subtype.

Atezolizumab With Neoadjuvant Anti-Human Epidermal Growth Factor Receptor 2 Therapy and Chemotherapy in Human Epidermal Growth Factor Receptor 2-Positive Early Breast Cancer: Primary Results of the Randomized Phase III IMpassion050 Trial

Combining standard of care (pertuzumab-trastuzumab [PH], chemotherapy) with cancer immunotherapy may potentiate antitumor immunity, cytotoxic activity, and patient outcomes in high-risk, human epidermal growth factor receptor 2 (HER2)–positive early breast cancer. We report the phase III IMpassion050 primary analysis of neoadjuvant atezolizumab, PH, and chemotherapy in these patients.

Deep Learning-Based Pathology Image Analysis Enhances Magee Feature Correlation With Oncotype DX Breast Recurrence Score

Background

Oncotype DX Recurrence Score (RS) has been widely used to predict chemotherapy benefits in patients with estrogen receptor-positive breast cancer. Studies showed that the features used in Magee equations correlate with RS. We aimed to examine whether deep learning (DL)-based histology image analyses can enhance such correlations.

Methods

We retrieved 382 cases with RS diagnosed between 2011 and 2015 from the Emory University and the Ohio State University. All patients received surgery. DL models were developed to detect nuclei of tumor cells and tumor-infiltrating lymphocytes (TILs) and segment tumor cell nuclei in hematoxylin and eosin (H&E) stained histopathology whole slide images (WSIs). Based on the DL-based analysis, we derived image features from WSIs, such as tumor cell number, TIL number variance, and nuclear grades. The entire patient cohorts were divided into one training set (125 cases) and two validation sets (82 and 175 cases) based on the data sources and WSI resolutions. The training set was used to train the linear regression models to predict RS. For prediction performance comparison, we used independent variables from Magee features alone or the combination of WSI-derived image and Magee features.

Results

The Pearson's correlation coefficients between the actual RS and predicted RS by DL-based analysis were 0.7058 (p-value = 1.32 × 10-13) and 0.5041 (p-value = 1.15 × 10-12) for the validation sets 1 and 2, respectively. The adjusted R 2 values using Magee features alone are 0.3442 and 0.2167 in the two validation sets, respectively. In contrast, the adjusted R 2 values were enhanced to 0.4431 and 0.2182 when WSI-derived imaging features were jointly used with Magee features.

Conclusion

Our results suggest that DL-based digital pathological features can enhance Magee feature correlation with RS.

Association of HER-2/CEP17 Ratio and HER-2 Copy Number With pCR Rate in HER-2-Positive Breast Cancer After Dual-Target Neoadjuvant Therapy With Trastuzumab and Pertuzumab

Objective

To explore the correlation between HER-2 status and pathological complete response (pCR) in HER-2-positive breast cancer after dual anti-HER-2 neoadjuvant therapy with trastuzumab and pertuzumab.

Methods

A total of 57 HER-2-positive breast cancer patients admitted to the Second Affiliated Hospital of Anhui Medical University and Xijing Hospital Affiliated to Air Force Military Medical University, between January 1, 2019 and September 30, 2020, were enrolled in this multicenter retrospective study. HER-2 status, including HER-2/CEP17 ratio and HER-2/cell number ratio, was detected by FISH. The correlation between HER-2 status/clinicopathological data and pCR was analyzed. The ROC curve was drawn to determine the cutoff value.

Results

IHC assessment revealed 40 (70.18%) patients with IHC 3+ and 17 (29.82%) with IHC 2+. 41/57 (71.93%) patients achieved pCR. FISH revealed that the ratio of HER-2/chromosome 17 centromere (HER-2/CEP17) (p<0.001) and the ratio of HER-2/cell number (p<0.001) was significantly correlated with the pCR rate. ROC analysis showed that patients with an HER-2/CEP17 ratio ≥4.495 or HER-2/cell number ≥11.650 have a high pCR rate after dual anti-HER-2 neoadjuvant therapy, suggesting its predictive significance.

Conclusion

The response to dual-targeted neoadjuvant therapy with trastuzumab and pertuzumab was adequate in hormone receptor-negative, HER-2-positive breast cancer patients. HER-2/CEP17 ratio and HER-2/cell number ratio were crucial for predicting efficacy.

Utility of Oncotype DX score in clinical management for T1 estrogen receptor positive, HER2 negative, and lymph node negative breast cancer

BACKGROUND

The management of estrogen receptor positive (ER+)/HER2- and lymph node (LN) negative breast cancers can be influenced by Oncotype DX recurrence score (RS) in the USA. However, the benefit of RS in T1 tumors (≤ 1 cm) is not clear.

METHODS

We retrieved 199 T1 ER+/HER2-/LN- breast cancer diagnosed between 1993 and 2016 that had undergone RS testing. The median follow-up time was 51 months. We examined the disease-free survival (DFS) and distant metastasis and their association with RS and other clinicopathologic features.

RESULTS

Of the 199 cases, 40 were T1a (≤ 0.5 cm) and 159 were T1b (> 0.5 cm to 1 cm) tumors. In the 40 T1a tumors, 11 would benefit from chemotherapy by the TAILORx study results. Of these T1a tumors, 36 were Nottingham grade 1/2, 3 were grade 3, and 1 was microinvasive carcinoma; 2 (5%) had local recurrence and 1 (2.5%) had distant metastasis to the bone. The only patient with T1a tumor (Nottingham grade 3, RS = 42) and distant metastasis to bone had received adjuvant chemotherapy. In the 159 T1b tumors, 25 would benefit chemotherapy by the TAILORx results. Of the T1b tumors, 149 were Nottingham grade 1/2 and 10 were grade 3. Nine (5.7%) had local recurrence and 2 (1.3%) had distant metastasis to bone and mediastinum, respectively. The two T1b tumors with distant metastasis had a RS 20 and Nottingham grade 2, and RS 27 and Nottingham grade 3, respectively. Both patients received adjuvant chemotherapy. In multivariate analysis of the entire cohort (T1a and T1b tumors), Nottingham tumor grade and receiving chemotherapy were significantly associated with DFS. In univariate analysis of the entire cohort, Nottingham tumor grade, receiving adjuvant chemotherapy, and RS were significantly associated with distant metastasis.

CONCLUSION

This study demonstrates that the metastatic rate of T1a and T1b ER+/HER2-/LN- breast cancer is very low. Patients with low grade (1 or 2), T1a ER+/HER2-/LN- breast cancer may not need RS for treatment decision-making; however, in patients with high-grade T1a or T1b ER+/HER2-/LN- breast cancer, RS analysis should be strongly considered.

Alliance A011801 (compassHER2 RD): postneoadjuvant T-DM1 + tucatinib/placebo in patients with residual HER2-positive invasive breast cancer

This report describes the rationale, purpose and design of A011801 (CompassHER2 RD), an ongoing prospective, multicenter, Phase III randomized trial. Eligible patients in the United States (US) and Canada with high-risk (defined as ER-negative and/or node-positive) HER2-positive (HER2+) residual disease (RD) after a predefined course of neoadjuvant chemotherapy and HER2-directed treatment are randomized 1:1 to adjuvant T-DM1 and placebo, versus T-DM1 and tucatinib. Patients have also received adjuvant radiotherapy and/or endocrine therapy, if indicated per standard of care guidelines. The primary objective of the trial is to determine if the invasive disease-free survival (iDFS) with T-DM1 plus tucatinib is superior to iDFS with T-DM1 plus placebo; other outcomes of interest include overall survival (OS), breast cancer-free survival (BCFS), distant recurrence-free survival (DRFS), brain metastases-free survival (BMFS) and disease-free survival (DFS). Correlative biomarker, quality of life (QoL) and pharmacokinetic (PK) end points are also evaluated.

Poor histologic tumor response after adjuvant therapy in basal-like HER2-positive breast carcinoma

AIMS

HER2-positive breast carcinomas are all treated with first-line anti-HER2 therapy. However, immunohistochemical and molecular profiling demonstrates significant heterogeneity among HER2-positive carcinomas. Basal-like HER2-positive breast carcinomas are poorly differentiated from pure HER2-positive breast carcinomas.

MATERIALS AND METHODS

Seventy-five patients with HER2-positive, ER- and PR-negative breast carcinomas who received anti-HER2 based neoadjuvant therapy were retrospectively analyzed. Thirty-seven cases were classified as basal-like HER2-positive breast carcinoma with any positivity for CK5/6, and thirty-eight cases were classified as pure HER2-positive breast carcinoma with completely negativity for CK5/6. The clinicopathological features and tumor responses after neoadjuvant therapy and outcomes were analyzed.

RESULTS

Compared to non-basal HER2-positive breast carcinoma, basal-like HER2-positive breast carcinoma showed distinctive histologic features including poor differentiation and syncytial tumor cells with pushing, invasive borders and a significantly higher proportion of apocrine metaplasia. They also demonstrated significantly higher histologic grade; 18/37 (48.6%) of basal-like carcinomas were grade 3, whereas only 5/38 (13.2%) of non-basal carcinomas were grade 3 (p = 0.001), Furthermore, basal-like HER2-positive breast carcinomas were more likely to be positive or completely negative for p53 (p = 0.009), and demonstrated a higher percentage of TP53 mutation (p = 0.17). These tumors were less responsive to anti-HER2 based neoadjuvant therapy, with Miller-Payne grades 1-3 higher than pure HER2-positive breast carcinoma (25/37 [67.6%] vs 16/38 [42.1%]), and the percentage of grade 4-5 was lower (12/37 [32.4%] vs 22/38 [57.9%]; p = 0.027).

CONCLUSIONS

Basal-like HER2-positive breast carcinoma has distinctive clinicopathological features and less histologic tumor response after neoadjuvant therapy. There is urgent need to recognize basal-like HER2-positive breast carcinoma to be treated precisely.

Clinicopathological response to neoadjuvant therapies and pathological complete response as a biomarker of survival in human epidermal growth factor receptor-2 enriched breast cancer - A retrospective cohort study

BACKGROUND

Human epidermal growth factor receptor-2 (HER2) is overexpressed in 20-25% of breast cancers. Complete eradication of disease following neoadjuvant therapies and chemotherapy has been referred to as pathological complete response (pCR).

AIMS

To determine clinicopathological predictors of pCR to neoadjuvant therapies and to evaluate pCR as a surrogate to enhanced survival.

METHODS

Consecutive female patients with HER2 positive (HER+) breast cancer managed surgically in a single institution between 2005 and 2015 were included. Descriptive statistics and binary logistic regression were used to determine predictors of pCR. Appraisal of pCR as a predictor of survival was performed using Kaplan-Meier curves and Cox regression analysis.

RESULTS

451 patients were included with a mean age of 56.6 ± 13.4 years (range 23-95). Disease-free (DFS) and overall survival (OS) was 82.3% (371/451) and 82.6% (376/451) respectively with a median follow-up of 108.0 months (range 3-184.0). 118 were treated in the neoadjuvant setting (26.2%): tumour size <50 mm (Odds Ratio (OR): 12.156, P = 0.023) and progesterone receptor negativity (OR: 2.762, P = 0.008) independently predicted breast pCR, while ductal carcinoma (OR: 3.203, P = 0.030) and grade 3 disease (OR: 2.788, P = 0.018) predicted axillary pCR. Both breast and axillary pCR predicted enhanced DFS (Hazard Ratio (HR): 0.470 & HR: 0.449) and OS (HR: 0.383 & HR: 0.307). Axillary pCR independently predicted improved OS (HR: 0.326).

CONCLUSION

pCR is sensitive biomarker and surrogate to survival outcomes in HER2+ breast cancer. Patients likely to achieve pCR may be predicted from traditional clinicopathological characteristics and molecular parameters.

HER2 Testing: Insights From Pathologists' Perspective on Technically Challenging HER2 FISH Cases

OBJECTIVE

College of American Pathologists and the American Society of Clinical Oncology guidelines provide straightforward criteria for HER2 interpretation in breast carcinomas; however, a subset of cases present unusual diagnostic dilemmas.

MATERIALS AND METHODS

Ten challenging HER2 fluorescence in situ hybridization (FISH) cases were selected for analysis. The study included a variety of problematic cases such as those with discordant immunohistochemistry (IHC) and FISH results, cases with high intratumoral variability in HER2 copy number, a case with a highly amplified clone in 5% to 10% of the tumor sample, and a case with tumor cells containing tightly clumped HER2 signals. Six high volume HER2 FISH laboratories performed and interpreted HER2 FISH (adding HER2 IHC if necessary). Interpretation strategies were discussed.

RESULTS

There was 100% concordance between laboratories in 4/10 cases. Tumors with increased intratumoral variability (tumors with high variability in HER2 copy number per cell but which otherwise do not fulfill College of American Pathologists and the American Society of Clinical Oncology criteria for heterogeneity) exhibited 100% concordance in 3/4 cases, but 1 case had only 50% agreement. Low positive HER2 cases (group 1 cases with <6 average HER2 copies/cell) had 1 laboratory disagreeing with the majority in 4/4 cases, and this was the only category with discordance between IHC and FISH methodologies. All laboratories identified the case with heterogeneity and interpreted it as positive. Five of the 6 laboratories interpreted the case with tightly clustered HER2 signals as positive.

CONCLUSIONS

This study offers specific observations and interpretation strategies that laboratories can use when confronted with difficult HER 2 cases. It then highlights communication strategies a laboratory may use to discuss these unusual HER2 results with the clinical team.

Retrospective observational study of HER2 immunohistochemistry in borderline breast cancer patients undergoing neoadjuvant therapy, with an emphasis on Group 2 (HER2/CEP17 ratio ≥2.0, HER2 copy number <4.0 signals/cell) cases

BACKGROUND

The ASCO/CAP guidance on HER2 testing in breast cancer (BC) has recently changed. Group 2 tumours with immunohistochemistry score 2+ and HER2/CEP17 ratio ≥2.0 and HER2 copy number <4.0 signals/cell were re-classified as HER2 negative. This study aims to examine the response of Group 2 tumours to neoadjuvant chemotherapy (NACT).

METHODS

749 BC cases were identified from 11 institutions. The association between HER2 groups and pathological complete response (pCR) was assessed.

RESULTS

54% of immunohistochemistry HER2 positive (score 3+) BCs showed pCR, compared to 19% of immunohistochemistry 2+ FISH amplified cases. 27% of Group 2 treated with HER2 targeted therapy achieved pCR, compared to 19 and 11% in the combined Groups 1 + 3 and Groups 4 + 5, respectively. No difference in pCR rates was identified between Group 2 and Group 1 or combined Groups 1 + 3. However, Group 2 response rate was higher than Groups 4 + 5 (p = 0.017).

CONCLUSION

No difference in pCR was detected in tumours with a HER2/CEP17 ratio ≥2.0 and a HER2 score 2+ by IHC when stratified by HER2 gene copy number. Our data suggest that ASCO/CAP HER2 Group 2 carcinomas should be evaluated further with respect to eligibility for HER2 targeted therapy.

HER2 Testing Characteristics Can Predict Residual Cancer Burden following Neoadjuvant Chemotherapy in HER2-Positive Breast Cancer

Objectives

The response to HER2-targeted neoadjuvant chemotherapy (NAC) in HER2-positive (+) breast cancer can be quantified using residual cancer burden (RCB) pathologic evaluation to predict relapse free/overall survival. However, more information is needed to characterize the relationship between patterns of HER2 testing results and response to NAC. We evaluated clinicopathologic characteristics associated with RCB categories in HER2+ patients who underwent HER2-directed NAC.

Methods

A retrospective chart review was conducted with Stage I-III HER2+ breast cancer cases following NAC and surgical resection. HER2 immunohistochemistry (IHC) staining and fluorescence in situ hybridization (FISH), histologic/clinical characteristics, hormone receptor status, and RCB scores (RCB-0, RCB-I, RCB-II, and RCB-III) were evaluated.

Results

64/151 (42.4%) patients with HER2+ disease had pathologic complete response (pCR). Tumors with suboptimal response (RCB-II and RCB-III) were more likely to demonstrate less than 100% HER2 IHC 3+ staining (p < 0.0001), lower HER2 FISH copies (p < 0.0001), and lower HER2/CEP17 ratios (p = 0.0015) compared to RCB-I and RCB-II responses. Estrogen receptor classification using ≥10% versus ≥1% staining showed greater association with higher RCB categories.

Conclusions

HER2+ characteristics show differing response to therapy despite all being categorized as positive; tumors with less than 100% IHC 3+ staining, lower HER2 FISH copies, and lower HER2/CEP17 ratios resulted in higher RCB scores.

Is there a correlation between HER2 gene amplification level and response to neoadjuvant treatment with trastuzumab and chemotherapy in HER2-positive breast cancer?

There are contradictory data regarding the correlation between HER2 amplification level determined by in situ hybridization and evolution after treatment with anti-HER2 therapies. The aim of this study was to correlate quantitative results of FISH (ratio HER2/CEP17 and number of HER2 signals/nucleus) with pathological response achieved after neoadjuvant treatment with trastuzumab and chemotherapy. For this purpose, we analysed 100 consecutive HER2-positive cases of breast carcinoma treated with neoadjuvant therapy. HER2 amplification determined by FISH was found in 92 of the 100 cases studied. pCR was obtained in 58% of the patients whose tumours presented amplification. In contrast, no pCR was obtained in the 8 patients with non-amplified tumours. A significant direct correlation between HER2 high amplification (HER2/CEP17 ratio > 5 or HER2 signals/nucleus > 10) and pCR was found. In conclusion, HER2 amplification levels are clinically relevant because they provide oncologists with valuable information on the possibilities of achieving pCR after neoadjuvant treatment.

Trastuzumab: More than a Guide in HER2-Positive Cancer Nanomedicine

HER2 overexpression, which occurs in a fifth of diagnosed breast cancers as well as in other types of solid tumors, has been traditionally linked to greater aggressiveness. Nevertheless, the clinical introduction of trastuzumab has helped to improve HER2-positive patients' outcomes. As a consequence, nanotechnology has taken advantage of the beneficial effects of the administration of this antibody and has employed it to develop HER2-targeting nanomedicines with promising therapeutic activity and limited toxicity. In this review, the molecular pathways that could be responsible for trastuzumab antitumor activity will be briefly summarized. In addition, since the conjugation strategies that are followed to develop targeting nanomedicines are essential to maintaining their efficacy and tolerability, the ones most employed to decorate drug-loaded nanoparticles and liposomes with trastuzumab will be discussed here. Thus, the advantages and disadvantages of performing this trastuzumab conjugation through adsorption or covalent bindings (through carbodiimide, maleimide, and click-chemistry) will be described, and several examples of targeting nanovehicles developed following these strategies will be commented on. Moreover, conjugation methods employed to synthesized trastuzumab-based antibody drug conjugates (ADCs), among which T-DM1 is well known, will be also examined. Finally, although trastuzumab-decorated nanoparticles and liposomes and trastuzumab-based ADCs have proven to have better selectivity and efficacy than loaded drugs, trastuzumab administration is sometimes related to side toxicities and the apparition of resistances. For this reason also, this review focuses at last on the important role that newer antibodies and peptides are acquiring these days in the development of HER2-targeting nanomedicines.

Evaluation of PD-L1, tumor-infiltrating lymphocytes, and CD8+ and FOXP3+ immune cells in HER2-positive breast cancer treated with neoadjuvant therapies

BACKGROUND

The tumor immune microenvironment plays a critical role in the prognosis and outcome of breast cancers. This study examined the role of tumor-infiltrating lymphocytes (TILs), CD8+, FOXP3+ lymphocytes, PD-L1 expression, and other clinicopathological parameters in HER2+ breast cancer and correlate with tumor response to neoadjuvant therapy.

METHODS

We included 173 HER2+ patients treated with neoadjuvant HER2-targeted chemotherapy regimens from 2010 to 2016. 67 cases had biopsy blocks to evaluate TIL, CD8, FOXP3, and PD-L1 immunohistochemistry staining. Tumors were classified as pCR vs non-pCR group. Clinicopathological parameters, TIL, CD8+ and FOXP3+ cell count, and PD-L1 expression were correlated with pCR rate.

RESULTS

Univariate analyses showed that pCR rate was significantly correlated with low PR, low ER, high Ki-67, high FOXP3, HER2 IHC3+ , high HER2 ratio and copy number. By multivariate analysis, Ki-67 was the only variable significantly correlated with pCR. PD-L1 expression was detected in 9.2% cases. TIL hotspot has a non-significant correlation with pCR rate (p = 0.096).

CONCLUSIONS

High Ki-67 is a strong predictor for pCR in HER2+ breast cancer. TIL and FOXP3 T cells may play a role in tumor response in HER2+ cancer. PD-L1 is expressed in a subset of HER2+ breast cancer, supporting a role of immunotherapy in treating a subset of HER2+ breast cancers. The role of PD-L1, TIL, and other markers of immunogenicity as predictors of response to neoadjuvant chemotherapy in HER2+ breast cancer should be further evaluated.