Image-based multiplex immune profiling of cancer tissues: translational implications. A report of the International Immuno-oncology Biomarker Working Group on Breast Cancer

Recent advances in the field of immuno-oncology have brought transformative changes in the management of cancer patients. The immune profile of tumours has been found to have key value in predicting disease prognosis and treatment response in various cancers. Multiplex immunohistochemistry and immunofluorescence have emerged as potent tools for the simultaneous detection of multiple protein biomarkers in a single tissue section, thereby expanding opportunities for molecular and immune profiling while preserving tissue samples. By establishing the phenotype of individual tumour cells when distributed within a mixed cell population, the identification of clinically relevant biomarkers with high-throughput multiplex immunophenotyping of tumour samples has great potential to guide appropriate treatment choices. Moreover, the emergence of novel multi-marker imaging approaches can now provide unprecedented insights into the tumour microenvironment, including the potential interplay between various cell types. However, there are significant challenges to widespread integration of these technologies in daily research and clinical practice. This review addresses the challenges and potential solutions within a structured framework of action from a regulatory and clinical trial perspective. New developments within the field of immunophenotyping using multiplexed tissue imaging platforms and associated digital pathology are also described, with a specific focus on translational implications across different subtypes of cancer. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Breast Cancer Histopathology in the Age of Molecular Oncology

For more than a century, microscopic histology has been the cornerstone for cancer diagnosis, and breast carcinoma is no exception. In recent years, clinical biomarkers, gene expression profiles, and other molecular tests have shown increasing utility for identifying the key biological features that guide prognosis and treatment of breast cancer. Indeed, the most common histologic pattern-invasive ductal carcinoma of no special type-provides relatively little guidance to management beyond triggering grading, biomarker testing, and clinical staging. However, many less common histologic patterns can be recognized by trained pathologists, which in many cases can be linked to characteristic biomarker and gene expression patterns, underlying mutations, prognosis, and therapy. Herein we describe more than a dozen such histomorphologic subtypes (including lobular, metaplastic, salivary analog, and several good prognosis special types of breast cancer) in the context of their molecular and clinical features.

Evaluation of tumor-infiltrating lymphocytes, PD-L1, and PIK3CA mutations and association with prognosis in HER2-positive early stage breast cancer

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) have predictive and prognostic potential in HER2-positive breast cancer (HER2+ BC). Programmed death-ligand 1 (PD-L1) is an immune checkpoint protein, with important roles in the tumor microenvironment, possibly in both tumor and immune cells (ICs), providing rationale for targeting with immune-checkpoint therapy. PIK3CA mutations are oncogenic, activating mutations, which are also of relevance in breast cancer. Herein, we investigate the frequency of TILs, PD-L1 and PIK3CA mutations, and whether these factors influence outcome, in early HER2+ BC.

MATERIALS AND METHODS

Stromal TILs (sTILs) and PD-L1 expressions were assessed using full tumor-sections and TMA, respectively, from 236 patients with HER2+ BC. TILs were assessed, according to a standardized method, as continuous measurement and according to three predefined categories: low (0-10%), intermediate (11-59%), and high (60-100%). PD-L1 immunohistochemistry (Ventana SP263) was evaluated and positivity defined as ≥1% expression in tumor and ICs. PIK3CA mutations (exons 9 and 20) were determined by pyrosequencing.

RESULTS

Fourteen percent of patients had high sTILs and 25% had a PIK3CA mutation. PD-L1 expression was more frequent in ICs (68%) than tumor cells (24%). Patients with low sTILs had a significantly worse overall survival (multivariate: HR 2.80; 95% CI 1.36-5.78; p = .02).

DISCUSSION

Patients with low sTILs had a significantly poorer survival, despite adequate treatment with adjuvant therapy.

A Multi-Stain Breast Cancer Histological Whole-Slide-Image Data Set from Routine Diagnostics

The analysis of FFPE tissue sections stained with haematoxylin and eosin (H&E) or immunohistochemistry (IHC) is essential for the pathologic assessment of surgically resected breast cancer specimens. IHC staining has been broadly adopted into diagnostic guidelines and routine workflows to assess the status of several established biomarkers, including ER, PGR, HER2 and KI67. Biomarker assessment can also be facilitated by computational pathology image analysis methods, which have made numerous substantial advances recently, often based on publicly available whole slide image (WSI) data sets. However, the field is still considerably limited by the sparsity of public data sets. In particular, there are no large, high quality publicly available data sets with WSIs of matching IHC and H&E-stained tissue sections from the same tumour. Here, we publish the currently largest publicly available data set of WSIs of tissue sections from surgical resection specimens from female primary breast cancer patients with matched WSIs of corresponding H&E and IHC-stained tissue, consisting of 4,212 WSIs from 1,153 patients.

Spatial analyses of immune cell infiltration in cancer: current methods and future directions: A report of the International Immuno-Oncology Biomarker Working Group on Breast Cancer

Modern histologic imaging platforms coupled with machine learning methods have provided new opportunities to map the spatial distribution of immune cells in the tumor microenvironment. However, there exists no standardized method for describing or analyzing spatial immune cell data, and most reported spatial analyses are rudimentary. In this review, we provide an overview of two approaches for reporting and analyzing spatial data (raster versus vector-based). We then provide a compendium of spatial immune cell metrics that have been reported in the literature, summarizing prognostic associations in the context of a variety of cancers. We conclude by discussing two well-described clinical biomarkers, the breast cancer stromal tumor infiltrating lymphocytes score and the colon cancer Immunoscore, and describe investigative opportunities to improve clinical utility of these spatial biomarkers. © 2023 The Pathological Society of Great Britain and Ireland.

PROCURE European consensus on breast cancer multigene signatures in early breast cancer management

Breast cancer multigene signatures (BCMS) have changed how patients with early-stage breast cancer (eBC) are managed, as they provide prognostic information and can be used to select patients who may avoid adjuvant chemotherapy. Clinical guidelines make recommendations on the use of BCMS; however, little is known on the current use of BCMS in clinical practice. We conduct a two-round Delphi survey to enquire about current use and perceived utility for specific patient profiles, and unmet needs of BCMS. Overall, 133 panellists experienced in breast cancer across 11 European countries have participated, most using BCMS either routinely (66.2%) or in selected cases (27.1%). Our results show that BCMS are mainly used to assess the risk of recurrence and to select patients for adjuvant chemotherapy; notably, no consensus has been reached on the lack of utility of BCMS for selecting the type of chemotherapy to administer. Also, there are discrepancies between the recommended and current use of BCMS in clinical practice, with use in certain patient profiles for which there is no supporting evidence. Our study suggests that physician education initiatives are needed to ensure the correct use and interpretation of BCMS to, ultimately, improve management of patients with eBC.

ONEST (Observers Needed to Evaluate Subjective Tests) Analysis of Stromal Tumour-Infiltrating Lymphocytes (sTILs) in Breast Cancer and Its Limitations

Tumour-infiltrating lymphocytes (TILs) reflect antitumour immunity. Their evaluation of histopathology specimens is influenced by several factors and is subject to issues of reproducibility. ONEST (Observers Needed to Evaluate Subjective Tests) helps in determining the number of observers that would be sufficient for the reliable estimation of inter-observer agreement of TIL categorisation. This has not been explored previously in relation to TILs. ONEST analyses, using an open-source software developed by the first author, were performed on TIL quantification in breast cancers taken from two previous studies. These were one reproducibility study involving 49 breast cancers, 23 in the first circulation and 14 pathologists in the second circulation, and one study involving 100 cases and 9 pathologists. In addition to the estimates of the number of observers required, other factors influencing the results of ONEST were examined. The analyses reveal that between six and nine observers (range 2-11) are most commonly needed to give a robust estimate of reproducibility. In addition, the number and experience of observers, the distribution of values around or away from the extremes, and outliers in the classification also influence the results. Due to the simplicity and the potentially relevant information it may give, we propose ONEST to be a part of new reproducibility analyses.

Digital image analysis and assisted reading of the HER2 score display reduced concordance: pitfalls in the categorisation of HER2-low breast cancer

AIMS

Digital image analysis (DIA) is used increasingly as an assisting tool to evaluate biomarkers, including human epidermal growth factor receptor 2 (HER2) in invasive breast cancer (BC). DIA can assist pathologists in HER2 evaluation by presenting quantitative information about the HER2 staining in APP assisted reading (AR). Concurrently, the HER2-low category (HER2-1+/2+ without HER2 gene amplification) has gained prominence due to newly developed antibody-drug conjugates. However, major inter- and intraobserver variability have been observed for the entity. The present quality assurance study investigated the concordance between DIA and AR in clinical use, especially concerning the HER2-low category.

METHODS AND RESULTS

HER2 immunohistochemistry (IHC) in 761 tumours from 727 patients was evaluated in tissue microarray (TMA) cores by DIA (Visiopharm HER2-CONNECT) and AR. Overall concordance between HER2-scores were 73% (n = 552, weighted-κ: 0.66), and 88% (n = 669, weighted-κ: 0.70), when combining HER2-0/1+. A total of 205 scores were discordant by one category, while four were discordant by two categories. A heterogeneous HER2 pattern was relatively common in the discordant cases and a pitfall in the categorisation of HER2-low BC. AR more commonly reassigned a lower HER2 score (from HER2-1+ to HER2-0) within the HER2-low subgroup (n = 624) compared with DIA.

CONCLUSION

DIA and AR display moderate agreement with heterogeneous and aberrant staining, representing a source of discordance and a pitfall in the evaluation of HER2.

Neither Tumor-Infiltrating Lymphocytes nor Cytotoxic T Cells Predict Enhanced Benefit from Chemotherapy in the DBCG77B Phase III Clinical Trial

Simple Summary

Apart from the direct killing of cancer cells, cyclophosphamide-based chemotherapy has been shown to induce an antitumor immune response, and is being used in combination with immunotherapies in cancer care. We assessed the interaction of chemotherapy with immune biomarkers expressed on primary tumor tissue from a randomized phase III clinical trial, and confirmed that the presence of tumor-infiltrating lymphocytes is linked to improved survival in premenopausal women with high-risk breast cancer, regardless of their treatment allocation. However, immune biomarkers including tumor-infiltrating lymphocytes do not predict extra benefit from cyclophosphamide chemotherapy. This finding applies across the major molecular subgroups, including non-luminal and basal breast cancers that tend to be more immunogenic, and are often considered the most suitable subsets for receiving immunotherapy.

Abstract

Recent studies have shown that immune infiltrates in the tumor microenvironment play a role in response to therapy, with some suggesting that patients with immunogenic tumors may receive increased benefit from chemotherapies. We evaluated this hypothesis in early breast cancer by testing the interaction between immune biomarkers and chemotherapy using materials from DBCG77B, a phase III clinical trial where high-risk premenopausal women were randomized to receive chemotherapy or no chemotherapy. Tissue microarrays were evaluated for tumor-infiltrating lymphocytes (TILs) assessed morphologically on hematoxylin and eosin-stained slides, and by immunohistochemistry for CD8, FOXP3, LAG-3, PD-1 and PD-L1. Following REMARK reporting guidelines, data analyses were performed according to a prespecified statistical plan, using 10-year invasive disease-free survival as the endpoint. Differences in survival probabilities between biomarker groups were evaluated by Kaplan–Meier and Cox proportional hazard ratio analyses and prediction for treatment benefit by an interaction test. Our results showed that stromal TILs were associated with an improved prognosis (HR = 0.93; p-value = 0.03), consistent with previous studies. However, none of the immune biomarkers predicted benefit from chemotherapy in the full study set nor within major breast cancer subtypes. Our study indicates that primary tumors with higher immune infiltration do not derive extra benefit from cyclophosphamide-based cytotoxic chemotherapy.

Consensus on the utility of breast cancer multigene signatures in routine clinical practice: Results of the PROCURE Project

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Background: Several Breast Cancer Multigene Signatures (BCMS) are available to profile early breast cancer (eBC) that according to current evidence, can provide reliable information on the risk of recurrence but the knowledge regarding their real use in clinical practice is scarce. The PROCURE Project aims to establish recommendations on the use of BCMS in clinical practice. Methods: A Scientific Committee consisting of 8 European experts in BC, including oncologists, pathologists, and surgeons, developed a Delphi questionnaire that was administered twice to clinicians across different European centers. The questionnaire included 5 sections: 1) Panelists’ profile and experience with BCMS, 2) Current clinical practice in eBC and use of BCMS, 3) Panelists’ opinion on the utility of the BCMS in eBC according to patient profiles, 4) Agreement with a set of recommendations on the use of BCMS in clinical practice and 5) Identification of unmet needs and future applications of BCMS. 70% agreement was used to determine consensus on a topic. Results: 133 panelists from 11 European countries completed both rounds of the survey. Most of the panelists worked in a teaching hospital (86.5%) and 72.2% of them were medical oncologists. 93.6% of the panelists used BCMS routinely or in selected patients and 73.4% had more than 5 years of experience using BCMS. According to panelists, for being useful in clinical practice BCMS should consider clinical and pathological features of the disease (91%). Additionally, BCMS must provide both, prognostic and predictive information (82%), and information on the risk of late distant recurrence from 5 to 10 years (74%), all based on prospective randomized clinical trials (85%). BCMS must also provide accurate results to guide adjuvant chemotherapy decision (81%). Regarding recommendations for improving BCMS utility, 76% of the panelists agreed that hospitals policies on the use of BCMS must be based on clinical practice guidelines. Panelists also agreed that patients should have the right to access their BCMS results to take part in the treatment decision (86%) and more training is needed for patients (79%) as well as oncologists (84%) and pathologists (82%). Finally, panelists mostly disagree on the fact that BCMS must be performed in all patients when BC is suspected (76%). Conclusions: The high degree of importance that panelists attributed to the fact that a BCMS should provide both prognostic and predictive information, reflects a misconception on the utility of BCMS as they are primarily prognostic tools but not predictive about the effect of a therapeutic intervention. Also, consensus reached on the need of providing risk of late recurrence from 5 to 10 years shows that panelists evaluate the long-term treatment even in the early setting.

Inter-observer agreement of tumor infiltrating lymphocytes in primary HER2-positive breast cancer and correlation between tissue microarray and full tumor-sections

Tumor infiltrating lymphocytes (TILs) have predictive and prognostic potential in HER2-positive breast cancer (HER2 + BC). Due to tumor heterogeneity, guidelines recommend evaluation on full tumor-sections over biopsies, but aren't clear regarding tissue microarrays (TMAs). Herein, we investigate the inter-observer agreement of TILs assessment in HER2 + BC on full-sections and TMAs using a standardized method. Two pathologists assessed TILs using HE full-sections and TMAs from 244 patients with HER2 + BC. TILs were assessed in 10% intervals; values <10% evaluated as 0%, 1% or 5%. Levels of agreement were evaluated using intraclass-coefficient (ICC), Kappa statistics and concordance analysis. For inter-observer agreement for full-sections, ICC was 0.93 (95% CI 0.89-0.95) and Kappa was 0.75, corresponding to acceptable and moderate agreement respectively. For TMAs, ICC was 0.73 (95% CI: 0.62-0.81) and Kappa 0.33, corresponding to unacceptable agreement. For association in matched TMA and full-sections, ICC was 0.64 (95% CI 0.55-0.71) and Lin's concordance correlation coefficient was 0.63 (95% CI 0.55-0.71), corresponding to unacceptable agreement. There is acceptable inter-observer agreement of TILs assessment on full-sections but not TMAs and discrepancy between full-sections and TMAs. TMA preparation must include consideration for representation of both entire tumor area and tumor-microenvironment to correctly define prognostic and predictive values of potential immuno-related biomarkers.

Abstract OT2-30-01: Nordictrip, a translational randomized phase-3study exploring the effect of the addition of capecitabine to carboplatinum-based chemotherapy in early “triple negative” breast cancer, ClinicalTrials.gov Identifier: NCT04335669

Background: A striking heterogeneity combined with an absence of highly efficient targeted treatments necessitates a continued effort to optimize the choice of chemotherapy for patients with triple negative breast cancer (TNBC). Neoadjuvant therapy has become the standard of care for high risk TNBC in order to potentially reduce breast and axillary surgery, start medical treatment early, allow genomic screening and guide post neoadjuvant therapy. Much attention is drawn to the use of immunotherapy in early TNBC, but there is also interesting data suggesting a potential to optimize the use of conventional chemotherapy. According to one meta-analysis including data from nine randomized controlled trials, the addition of platinum salts in the preoperative setting increases the pathologic complete response (pCR) rate in TNBC (Poggio 2018). A second meta-analysis, evaluating the effect of capecitabine in early breast cancer indicates an additional benefit from adding capecitabine to conventional chemotherapy in terms of an increased recurrence-free survival in the subset of TNBC (Mackelenbergh SABCS 2019). An adjuvant trial in TNBC suggests that the beneficial effect of capecitabine may be confined to patients with a non-basal like phenotype of TNBC (Lluch 2020), a subset that correlates with the homologous repair non-deficient subset which constitutes 41 % of TNBC in a mainly south Swedish population based cohort (Staaf 2019). The effect of capecitabine in platinum treated early TNBC is unknown. Objectives: We are conducting a multi-center randomized controlled trial evaluating the effect on the pCR rate by the addition of capecitabine to optimal platinum based and dose dense preoperative chemotherapy in early TNBC. Method: 820 patients (pts) with early TNBC stage 1 (≥20 mm) - 3 will be randomized 1:1 between two treatment arms A and B. A: Epirubicine Cyclophosphamide (EC) q2w x 4 followed by Carboplatin AUC 5 q3w with weekly paclitaxel x 12. B: Epirubicine Cyclophosphamide with capecitabine daily for two weeks (CEX) q3w x 4 followed by Carboplatin AUC 5 q3w with weekly paclitaxel x 12 The primary endpoint is pCR rate in the different treatment strata, and the primary translational endpoint will be the potential difference of treatment effect stratified for HRD-status in the primary tumor. Secondary endpoints include IDFS in subsets of TNBC, eg according to gene-expression-based subtypes of TNBC (Lehmann 2011, Burstein 2015), and germline mutation status of hereditary breast cancer genes. Tumor material for genotypig is collected at baseline, at surgery and optionally after two treatment cycles. Sequential blood samples are collected for tsDNA analysis during and after treatment termination. Results: The trial, which is a collaborative effort between the national breast cancer groups in the participating countries, has been postponed by the pandemic but is now recruiting according to plan. So far 56 patients out of 820 have been recruited at 15 sites in Sweden and Denmark. Additional Sites in Sweden, Denmark, Iceland and Finland are preparing to join the study. For update please see: www.NordicTrip.se; E-mail address: Nordictrip.onkologi@skane.se

Citation Format: Niklas Loman, Barbro Linderholm, Johan Ahlgren, Siker Kimbung, Lina Zander, Heidi Grill Magnusson, Eva-Christin Kjellman, Ann Julia Raaberg, Maj-Britt Raaby Jensen, Åke Borg, Johan Staaf, Anders Ståhlberg, Pär-Ola Bendahl, Anne-Vibeke Laenkholm, Minna Tanner, Olöf Bjarnadóttir, Oskar Johannsson, Bent Ejlertsen, Henrik Lindman. Nordictrip, a translational randomized phase-3study exploring the effect of the addition of capecitabine to carboplatinum-based chemotherapy in early “triple negative” breast cancer, ClinicalTrials.gov Identifier: NCT04335669 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-30-01.

Abstract P4-06-08: Consensus on the utility of breast cancer multigene signatures in routine clinical practice among European breast cancer specialists - 1st results of the PROCURE project

Background: Several genomic assays are available to profile early breast cancer (eBC) that according to current evidence, can provide reliable information on the risk of recurrence. However, little is known regarding their current clinical use and the perception of their utility among European breast cancer (BC) specialists. The PROCURE project aims to develop a consensus on the utility of BC multigene signatures (BCMS) in treatment decision making for different BC patient profiles. Methods: A Scientific Committee of 8 experts in BC from 8 European countries developed a Delphi questionnaire that was administered in two waves to experienced clinicians across Europe with expertise in the use of BCMS. The questionnaire included 5 sections: 1) Participants’ profile and experience with BCMS. 2) Current clinical practice in eBC and use of BCMS. 3) Participants’ opinion on the utility of the BCMS in eBC according to patient profiles. 4) Agreement with a set of recommendations on the use of BCMS in clinical practice. 5) Identification of unmet needs and future applications of BCMS. 70% agreement was used to determine consensus on a topic. Results: 163 BC experts were invited to answer anonymously the online Delphi questionnaire. At wave 2 closure (1st of June 2021) 133 panelists from 11 European countries (grouped in 5 regions) completed both rounds of the survey. Panelists were 48.8 years old (± 9.5). 86.5% of them worked in a teaching hospital, 72.2% were medical oncologists and 12.0% pathologists, the distribution of the specialities of the participants differed by region. The mean number of patients seen, treated or diagnosed on a weekly basis was 36.4 with statistical differences among regions and specialities. The ratio of eBC on BC patients was 63.5%, similar between regions but showed statistical differences among specialities. 93.2% of the panelists used BCMS routinely or in selected patients, with statistical differences among regions, and 73.4% had more than 5 years of experience using BCMS, however the experience of participants varies by regions and specialities. After the 2nd wave, experts panelists in BC management reached a consensus on 50% (35/70) of the items asked on clinical utility, recommendations and future applications of BCMS. Conclusions: European panelists that participated in the PROCURE study showed an extensive experience in the management of BC patients and on the use of BCMS. Detailed results from the 2nd wave will be presented during the 2021 SABCS meeting to engage larger discussion with symposium participants about the agreement or disagreement reached on the main topics.

Citation Format: Giuseppe Curigliano, Fatima Cardoso, Michael Gnant, Nadia Harbeck, Judy King, Anne-Vibeke Laenkholm, Frédérique Penault-Llorca, Aleix Prat. Consensus on the utility of breast cancer multigene signatures in routine clinical practice among European breast cancer specialists - 1st results of the PROCURE project [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-06-08.

Capsulectomy Can Successfully Treat Chronic Encapsulated Breast Seroma: A Case Report

Chronic encapsulated seroma following breast cancer surgery is a rare entity, and management is challenging. We present clinical and pathologic findings in a patient with previous node-negative breast cancer and an extensive history of chronic bilateral seromas, successfully treated with capsulectomy. This is the first report of fibrous encapsulated breast seroma with bilateral presentation and late onset, following mastectomy with no prior axillary dissection. When managing breast seroma refractory to conventional treatment, the diagnosis of encapsulated seroma should be considered, followed by prompt capsulectomy.

Intra-Tumour Heterogeneity Is One of the Main Sources of Inter-Observer Variation in Scoring Stromal Tumour Infiltrating Lymphocytes in Triple Negative Breast Cancer

Stromal tumour infiltrating lymphocytes (sTILs) are a strong prognostic marker in triple negative breast cancer (TNBC). Consistency scoring sTILs is good and was excellent when an internet-based scoring aid developed by the TIL-WG was used to score cases in a reproducibility study. This study aimed to evaluate the reproducibility of sTILs assessment using this scoring aid in cases from routine practice and to explore the potential of the tool to overcome variability in scoring. Twenty-three breast pathologists scored sTILs in digitized slides of 49 TNBC biopsies using the scoring aid. Subsequently, fields of view (FOV) from each case were selected by one pathologist and scored by the group using the tool. Inter-observer agreement was good for absolute sTILs (ICC 0.634, 95% CI 0.539-0.735, p < 0.001) but was poor to fair using binary cutpoints. sTILs heterogeneity was the main contributor to disagreement. When pathologists scored the same FOV from each case, inter-observer agreement was excellent for absolute sTILs (ICC 0.798, 95% CI 0.727-0.864, p < 0.001) and good for the 20% (ICC 0.657, 95% CI 0.561-0.756, p < 0.001) and 40% (ICC 0.644, 95% CI 0.546-0.745, p < 0.001) cutpoints. However, there was a wide range of scores for many cases. Reproducibility scoring sTILs is good when the scoring aid is used. Heterogeneity is the main contributor to variance and will need to be overcome for analytic validity to be achieved.

Assessment of Ki67 in Breast Cancer: Updated Recommendations From the International Ki67 in Breast Cancer Working Group

Ki67 immunohistochemistry (IHC), commonly used as a proliferation marker in breast cancer, has limited value for treatment decisions due to questionable analytical validity. The International Ki67 in Breast Cancer Working Group (IKWG) consensus meeting, held in October 2019, assessed the current evidence for Ki67 IHC analytical validity and clinical utility in breast cancer, including the series of scoring studies the IKWG conducted on centrally stained tissues. Consensus observations and recommendations are: 1) as for estrogen receptor and HER2 testing, preanalytical handling considerations are critical; 2) a standardized visual scoring method has been established and is recommended for adoption; 3) participation in and evaluation of quality assurance and quality control programs is recommended to maintain analytical validity; and 4) the IKWG accepted that Ki67 IHC as a prognostic marker in breast cancer has clinical validity but concluded that clinical utility is evident only for prognosis estimation in anatomically favorable estrogen receptor–positive and HER2-negative patients to identify those who do not need adjuvant chemotherapy. In this T1-2, N0-1 patient group, the IKWG consensus is that Ki67 5% or less, or 30% or more, can be used to estimate prognosis. In conclusion, analytical validity of Ki67 IHC can be reached with careful attention to preanalytical issues and calibrated standardized visual scoring. Currently, clinical utility of Ki67 IHC in breast cancer care remains limited to prognosis assessment in stage I or II breast cancer. Further development of automated scoring might help to overcome some current limitations.

Rates of re-excision and conversion to mastectomy after breast-conserving surgery with or without oncoplastic surgery: a nationwide population-based study

Background

There is no consensus regarding the impact of oncoplastic surgery (OPS) on rates of re‐excision and conversion to mastectomy following breast‐conserving surgery (BCS). Here these two outcomes after BCS and OPS were compared in a nationwide population‐based setting.

Methods

In Denmark, all OPS is registered and categorized into volume displacement, volume reduction or volume replacement. Patients who underwent BCS or OPS between 2012 and 2018 were selected from the Danish Breast Cancer Group database. Multivariable analyses were performed to adjust for confounders, and propensity score matching to limit potential confounding by indication bias.

Results

A total of 13 185 patients (72·5 per cent) underwent BCS and 5003 (27·5 per cent) OPS. Volume displacement was used in 4171 patients (83·4 per cent), volume reduction in 679 (13·6 per cent) and volume replacement in 153 (3·1 per cent). Re‐excision rates were 15·6 and 14·1 per cent after BCS and OPS respectively. After adjusting for confounders, patients were less likely to have a re‐excision following OPS than BCS (odds ratio (OR) 0·80, 95 per cent c.i. 0·72 to 0·88), specifically after volume displacement and reduction. The rate of conversion to mastectomy was similar after OPS and BCS (3·2 versus 3·7 per cent; P = 0·105), but with a lower risk in adjusted analysis (OR 0·69, 0·58 to 0·84), specifically after volume displacement and reduction procedures. Findings were similar after propensity score matching.

Conclusion

A modest decrease in re‐excision rate and less frequent conversion to mastectomy were observed after OPS compared with BCS.

Induction of PIK3CA alterations during neoadjuvant letrozole may improve outcome in postmenopausal breast cancer patients

PURPOSE

Estrogen receptor positive (ER+) breast cancer constitutes almost 85% of all breast cancer patients and are a genetically highly heterogenic group. Data on the association of somatic alterations to outcome and prognosis are however sparse. In this neoadjuvant endocrine phase II trial including postmenopausal breast cancer patients with ER+, HER2 normal breast cancer, we investigated the rate of pathogenic mutations before and after treatment as well as the association with treatment response and survival.

METHODS

Pretreatment and posttreatment tumour samples from 109 patients treated with neoadjuvant letrozole were collected and analysed with Next Generation Sequencing utilizing a panel of 12 genes (ALK, BRAF, EGFR, ERBB2, ERBB3, ESR1, KIT, KRAS, NRAS, PDGFRA, PIK3CA, and RAF1). Residual disease was assessed by a modified Miller Payne scale and the Residual Cancer Burden index. Survival data were collected prospectively.

RESULTS

Among the 109 patients, 52 had at least one pathogenic mutation in the pretreatment sample and 60 in the posttreatment sample. The most frequently mutated gene was PIK3CA, followed by EGFR and KRAS. Twelve different pathogenic PIK3CA mutations were identified, primarily in exon 20 and exon 9. An altered PIK3CA mutation profile from the pre- to the posttreatment specimen was significantly associated to improved pathological outcome. Overall and Disease-Free Survival benefits in PIK3CA mutated patients was observed.

CONCLUSION

Considerable heterogeneity was identified both among patients and between pre- and posttreatment samples. PIK3CA has the potential to be a predictive biomarker. To further assess the implications of a treatment related altered PIK3CA mutation profile, more data are needed.

Genome-wide association study identifies 32 novel breast cancer susceptibility loci from overall and subtype-specific analyses

Breast cancer susceptibility variants frequently show heterogeneity in associations by tumor subtype1-3. To identify novel loci, we performed a genome-wide association study including 133,384 breast cancer cases and 113,789 controls, plus 18,908 BRCA1 mutation carriers (9,414 with breast cancer) of European ancestry, using both standard and novel methodologies that account for underlying tumor heterogeneity by estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 status and tumor grade. We identified 32 novel susceptibility loci (P < 5.0 × 10-8), 15 of which showed evidence for associations with at least one tumor feature (false discovery rate < 0.05). Five loci showed associations (P < 0.05) in opposite directions between luminal and non-luminal subtypes. In silico analyses showed that these five loci contained cell-specific enhancers that differed between normal luminal and basal mammary cells. The genetic correlations between five intrinsic-like subtypes ranged from 0.35 to 0.80. The proportion of genome-wide chip heritability explained by all known susceptibility loci was 54.2% for luminal A-like disease and 37.6% for triple-negative disease. The odds ratios of polygenic risk scores, which included 330 variants, for the highest 1% of quantiles compared with middle quantiles were 5.63 and 3.02 for luminal A-like and triple-negative disease, respectively. These findings provide an improved understanding of genetic predisposition to breast cancer subtypes and will inform the development of subtype-specific polygenic risk scores.

Pitfalls in assessing stromal tumor infiltrating lymphocytes (sTILs) in breast cancer

Stromal tumor-infiltrating lymphocytes (sTILs) are important prognostic and predictive biomarkers in triple-negative (TNBC) and HER2-positive breast cancer. Incorporating sTILs into clinical practice necessitates reproducible assessment. Previously developed standardized scoring guidelines have been widely embraced by the clinical and research communities. We evaluated sources of variability in sTIL assessment by pathologists in three previous sTIL ring studies. We identify common challenges and evaluate impact of discrepancies on outcome estimates in early TNBC using a newly-developed prognostic tool. Discordant sTIL assessment is driven by heterogeneity in lymphocyte distribution. Additional factors include: technical slide-related issues; scoring outside the tumor boundary; tumors with minimal assessable stroma; including lymphocytes associated with other structures; and including other inflammatory cells. Small variations in sTIL assessment modestly alter risk estimation in early TNBC but have the potential to affect treatment selection if cutpoints are employed. Scoring and averaging multiple areas, as well as use of reference images, improve consistency of sTIL evaluation. Moreover, to assist in avoiding the pitfalls identified in this analysis, we developed an educational resource available at www.tilsinbreastcancer.org/pitfalls.

The path to a better biomarker: application of a risk management framework for the implementation of PD-L1 and TILs as immuno-oncology biomarkers in breast cancer clinical trials and daily practice

Immune checkpoint inhibitor therapies targeting PD-1/PD-L1 are now the standard of care in oncology across several hematologic and solid tumor types, including triple negative breast cancer (TNBC). Patients with metastatic or locally advanced TNBC with PD-L1 expression on immune cells occupying ≥1% of tumor area demonstrated survival benefit with the addition of atezolizumab to nab-paclitaxel. However, concerns regarding variability between immunohistochemical PD-L1 assay performance and inter-reader reproducibility have been raised. High tumor-infiltrating lymphocytes (TILs) have also been associated with response to PD-1/PD-L1 inhibitors in patients with breast cancer (BC). TILs can be easily assessed on hematoxylin and eosin-stained slides and have shown reliable inter-reader reproducibility. As an established prognostic factor in early stage TNBC, TILs are soon anticipated to be reported in daily practice in many pathology laboratories worldwide. Because TILs and PD-L1 are parts of an immunological spectrum in BC, we propose the systematic implementation of combined PD-L1 and TIL analyses as a more comprehensive immuno-oncological biomarker for patient selection for PD-1/PD-L1 inhibition-based therapy in patients with BC. Although practical and regulatory considerations differ by jurisdiction, the pathology community has the responsibility to patients to implement assays that lead to optimal patient selection. We propose herewith a risk-management framework that may help mitigate the risks of suboptimal patient selection for immuno-therapeutic approaches in clinical trials and daily practice based on combined TILs/PD-L1 assessment in BC. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Abstract P4-10-18: Changes in tumour infiltrating lymphocytes during neoadjuvant endocrine therapy and possible clinical implications for guiding therapy

Background: Stromal Tumour Infiltrating Lymphocytes (sTILs) has been established as a predictive biomarker for response to neoadjuvant chemotherapy irrespective of subtype. While increased sTIL levels is associated with prolonged survival among patients with triple-negative and HER2 positive breast cancer increased sTILs has in Estrogen Receptor positive (ER+) breast cancer been suggested to be an adverse prognostic factor. It has been hypothesised that differences in the cellular composition of immune cells may explain the dissimilarity in prognostic impact according to breast cancer subtype.

Here, we report data from a neoadjuvant phase II study, treating postmenopausal patients with primary ER+, HER2 negative, operable breast cancer with letrozole for four months by the Danish Breast Cancer Group (DBCG). We analysed the association of sTILs, and changes in sTILs during neoadjuvant endocrine treatment (NET), with pathological response and correlation with other clinicopathological variables such as Ki67, as potential biomarkers for risk-stratification of patients following NET.

Method: 113 postmenopausal patients with ER+, HER2 negative breast cancer were treated with NET for four months. Endpoint was pathological response assessed by a modified Miller Payne scale and the Residual Cancer Burden (RCB) score. Pretherapeutic core biopsies and post therapeutic surgical specimens were assessed centrally for the percentage of sTILs on HE sections according to the International TILs working group guidelines. sTILs association to pathological response were assessed with univariate logistic regression. Odds Ratio (OR) was estimated with a 95 % confidence interval. Correlation of sTILs and Ki67 were tested with Pearson´s correlation coefficient. Changes in sTILs with a paired t-test. Level of significance was set to 5 %.

Results: sTILs concentration increased with mean 6.8 % (p &lt;.0001) during treatment in the assessable patients (range -39 % - 60 %). Forty-four percent had no pathological response as assessed by the modified Miller Payne scale and 11 % had RCB-Class III after NET. Increase in sTILs was significantly associated with poorer pathological response with OR=1.38 (95 % CI: 1.05 - 1.82; p = 0.03) per 10 % increase for no pathological response, and correspondingly OR=1.78 (95 % CI: 1.27 - 2.50; p &lt;.0001) for higher level RCB-class per 10 % increase.

The correlation between pre-therapeutic sTILs and Ki67 was moderate (Pearson 0.4; p = 0.0004), however the association grew stronger post treatment (Pearson 0.5; p &lt;.0001).

Conclusion: Increased sTILs activity during NET was associated with poor treatment response. An increase in sTILs during NET could be considered indictive for potential immunogenic tumours, suggesting that patients with increasing sTIL in residual disease after NET might derive benefit from the addition of immunotherapy.

We found a significant correlation between sTILs and Ki67 levels. Ki67 has been established as a window of opportunity biomarker for antiproliferative response. Combining biomarkers of antiproliferative response such as Ki67 with biomarkers of immunogenetic significance might be important to determine optimal combination of adjuvant therapy. A window of opportunity study with an aromatase inhibitor could show if it is feasible to detect a rise in sTILs early enough to guide adjuvant treatment in the perioperative setting.

Citation Format: Signe Korsgaard Skriver, Maj-Britt Jensen, Ann Soegaard Knoop, Bent Ejlertsen, Anne-Vibeke Laenkholm. Changes in tumour infiltrating lymphocytes during neoadjuvant endocrine therapy and possible clinical implications for guiding therapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-10-18.

Analytical validation of a standardised scoring protocol for Ki67 immunohistochemistry on breast cancer excision whole sections: an international multicentre collaboration

AIMS

The nuclear proliferation marker Ki67 assayed by immunohistochemistry has multiple potential uses in breast cancer, but an unacceptable level of interlaboratory variability has hampered its clinical utility. The International Ki67 in Breast Cancer Working Group has undertaken a systematic programme to determine whether Ki67 measurement can be analytically validated and standardised among laboratories. This study addresses whether acceptable scoring reproducibility can be achieved on excision whole sections.

METHODS AND RESULTS

Adjacent sections from 30 primary ER⁺ breast cancers were centrally stained for Ki67 and sections were circulated among 23 pathologists in 12 countries. All pathologists scored Ki67 by two methods: (i) global: four fields of 100 tumour cells each were selected to reflect observed heterogeneity in nuclear staining; (ii) hot-spot: the field with highest apparent Ki67 index was selected and up to 500 cells scored. The intraclass correlation coefficient (ICC) for the global method [confidence interval (CI) = 0.87; 95% CI = 0.799-0.93] marginally met the prespecified success criterion (lower 95% CI ≥ 0.8), while the ICC for the hot-spot method (0.83; 95% CI = 0.74-0.90) did not. Visually, interobserver concordance in location of selected hot-spots varies between cases. The median times for scoring were 9 and 6 min for global and hot-spot methods, respectively.

CONCLUSIONS

The global scoring method demonstrates adequate reproducibility to warrant next steps towards evaluation for technical and clinical validity in appropriate cohorts of cases. The time taken for scoring by either method is practical using counting software we are making publicly available. Establishment of external quality assessment schemes is likely to improve the reproducibility between laboratories further.

Basal biomarkers nestin and INPP4B predict gemcitabine benefit in metastatic breast cancer: Samples from the phase III SBG0102 clinical trial

In a formal prospective-retrospective analysis of the phase III SBG0102 clinical trial randomizing metastatic breast cancer patients to gemcitabine-docetaxel or to single agent docetaxel, patients with basal-like tumors by PAM50 gene expression had significantly better overall survival in the gemcitabine arm. By immunohistochemistry (IHC), triple negative status was not predictive, but more specific biomarkers have since become available defining basal-like by nestin positivity or loss of inositol-polyphosphate-4-phosphate (INPP4B). Here, we evaluate their capacity to identify which patients benefit from gemcitabine in the metastatic setting. Nestin and INPP4B staining and interpretation followed published methods. A prespecified statistical plan evaluated the primary hypothesis that patients with basal-like breast cancer, defined as "nestin+ or INPP4B-", would have superior overall survival on gemcitabine-docetaxel when compared to docetaxel. Interaction tests, Kaplan-Meier curves and forest plots were used to assess prognostic and predictive capacities of biomarkers relative to treatment. Among 239 cases evaluable for our study, 36 (15%) had been classified as basal-like by PAM50. "Nestin+ or INPP4B-" was observed in 41 (17%) of the total cases and was significantly associated with PAM50 basal-like subtype. Within an estimated median follow-up of 13 years, patients assigned as IHC basal "nestin+ or INPP4B-" had significantly better overall survival on gemcitabine-docetaxel versus docetaxel monotherapy (HR = 0.31, 95%CI: 0.16-0.60), whereas no differences were observed for other patients (HR = 0.99), p-interaction < 0.01. In the metastatic setting, women with IHC basal breast cancers defined as "nestin+ or INPP4B-" have superior overall survival when randomized to gemcitabine-containing chemotherapy compared to docetaxel alone. These findings need to be validated using larger prospective-retrospective phase III clinical trials series.

Correlation between circulating cell-free PIK3CA tumor DNA levels and treatment response in patients with PIK3CA-mutated metastatic breast cancer

Liquid biopsies focusing on the analysis of cell-free circulating tumor DNA (ctDNA) may have important clinical implications for personalized medicine, including early detection of cancer, therapeutic guidance, and monitoring of recurrence. Mutations in the oncogene, PIK3CA, are frequently observed in breast cancer and have been suggested as a predictive biomarker for PI3K-selective inhibitor treatment. In this study, we analyzed the presence of PIK3CA mutations in formalin-fixed, paraffin-embedded, metastatic tissue and corresponding ctDNA from serum of patients with advanced breast cancer using a highly sensitive, optimized droplet digital PCR (ddPCR) assay. We found 83% of patients with PIK3CA mutation in the metastatic tumor tissue also had detectable PIK3CA mutations in serum ctDNA. Patients lacking the PIK3CA mutation in corresponding serum ctDNA all had nonvisceral metastatic disease. Four patients with detectable PIK3CA-mutated ctDNA were followed with an additional serum sample during oncological treatment. In all cases, changes in PIK3CA ctDNA level correlated with treatment response. Our results showed high concordance between detection of PIK3CA mutations in tumor tissue and in corresponding serum ctDNA and suggest that serum samples from patients with advanced breast cancer and ddPCR may be used for PIK3CA mutation status assessment to complement imaging techniques as an early marker of treatment response.

Williams syndrome transcription factor (WSTF) acts as an activator of estrogen receptor signaling in breast cancer cells and the effect can be abrogated by 1α,25-dihydroxyvitamin D3

A majority of estrogen receptor positive (ER+) breast cancers are growth stimulated by estrogens. The ability to inhibit the ER signaling pathway is therefore of critical importance in the current treatment of ER+ breast cancers. It has been reported that 1α,25-dihydroxyvitamin D₃ down-regulates the expression of the CYP19A1 gene, encoding the aromatase enzyme that catalyzes the synthesis of estradiol. Furthermore, 1α,25-dihydroxyvitamin D₃ has also been reported to down-regulate the expression of estrogen receptor α (ERα), the main mediator of ER signaling. This study reports a novel transcription factor critical to 1α,25-dihydroxyvitamin D₃-mediated regulation of estrogenic signaling in MCF-7 breast cancer cells. We have investigated the molecular mechanisms for the 1α,25-dihydroxyvitamin D₃-mediated down-regulation of CYP19A1 and ERα gene expression in human MCF-7 breast cancer cells and found that Williams syndrome transcription factor (WSTF) plays a key role by binding to the promoters of CYP19A1 and ERα. Although sometimes reported as an inhibitor of gene expression, we found that WSTF acts as an activator of the promoter activity of both CYP19A1 and ERα. Silencing of WSTF by siRNA transfection resulted in decreased aromatase-dependent cell growth as well as decreased ER signaling in the cells. When cells were treated with 1α,25-dihydroxyvitamin D₃, WSTF was dissociated from the promoters and the promoter activities of CYP19A1 and ERα were decreased. We have measured the expression of WSTF in ER-positive tumor-samples from breast cancer patients and found that WSTF is expressed in the majority of the investigated samples and that the expression is higher in cancer tissue than in normal tissue. However, we were not able to show any significant association between the WSTF expression in the tumor and the disease free and overall survival in this patient group who have received adjuvant tamoxifen treatment, nor between the WSTF expression and the expression of ERα, progesterone receptor or HER2. The major conclusions of this study are that WSTF acts as an activator of ER signaling in MCF-7 breast cancer cells, that this action can be inhibited by 1α,25-dihydroxyvitamin D₃, and that the expression of WSTF is higher in breast cancer tissue than in normal tissue. WSTF may by a new target for treatment of estrogen-dependent breast cancer cell growth.

The ability of PAM50 risk of recurrence score to predict 10-year distant recurrence in hormone receptor-positive postmenopausal women with special histological subtypes

INTRODUCTION

The Prosigna-PAM50 risk of recurrence (ROR) score has been validated in randomized clinical trials to predict 10-year distant recurrence (DR) in hormone receptor-positive breast cancer. Here, we examine the ability of Prosigna for predicting DR at 10 years in a subgroup of postmenopausal breast cancer patients with special histological subtypes.

METHODS

Using the population based Danish Breast Cancer Group database, follow-up data were collected on all patients diagnosed from 2000 to 2003 with estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2) normal breast cancer who by nationwide guidelines were treated with 5 year of endocrine therapy (N = 2558). Among patients with 1 to 3 positive lymph nodes or a tumor size >20 mm, we identified 1570 with invasive ductal carcinoma (IDC) and 89 with special histological subtypes (apocrine, medullary, mucinous, papillary, secretory, tubular, neuroendocrine) who were tested with Prosigna. Fine and Gray models were applied to determine the prognostic value of the Prosigna-PAM50 ROR score for DR special subtypes as compared to IDC.

RESULTS

Median follow-up for DR was 9.2 year and for OS 15.2 year. The 10-year DR rate for the special subtypes was 9.2% (95% CI: 4.0% to 17.2%) as compared to 13.7% (95% CI: 11.9% to 15.7%) for IDC. The 10-year OS was 74.2% (95% CI: 63.7% to 82.0%) for the special subtypes and 75.4% (95% CI: 73.2% to 77.4%) for IDC. Prosigna showed a statistical significant association of the continuous ROR score with risk of DR for both IDC and the special subtypes (IDC: p < .0001; special subtypes: p = .01).

CONCLUSION

In the present study, we demonstrated that Prosigna-PAM50 continuous ROR score added significant prognostic information for 10-year DR in postmenopausal patients with special subtypes (tumor size >20 mm or 1 to 3 positive lymph nodes) and ER-positive, HER2-normal early breast cancer.

An inter-observer Ki67 reproducibility study applying two different assessment methods: on behalf of the Danish Scientific Committee of Pathology, Danish breast cancer cooperative group (DBCG)

INTRODUCTION

In 2011, the St. Gallen Consensus Conference introduced the use of pathology to define the intrinsic breast cancer subtypes by application of immunohistochemical (IHC) surrogate markers ER, PR, HER2 and Ki67 with a specified Ki67 cutoff (>14%) for luminal B-like definition. Reports concerning impaired reproducibility of Ki67 estimation and threshold inconsistency led to the initiation of this quality assurance study (2013-2015). The aim of the study was to investigate inter-observer variation for Ki67 estimation in malignant breast tumors by two different quantification methods (assessment method and count method) including measure of agreement between methods.

MATERIAL AND METHODS

Fourteen experienced breast pathologists from 12 pathology departments evaluated 118 slides from a consecutive series of malignant breast tumors. The staining interpretation was performed according to both the Danish and Swedish guidelines. Reproducibility was quantified by intra-class correlation coefficient (ICC) and Lights Kappa with dichotomization of observations at the larger than (>) 20% threshold. The agreement between observations by the two quantification methods was evaluated by Bland-Altman plot.

RESULTS

For the fourteen raters the median ranged from 20% to 40% by the assessment method and from 22.5% to 36.5% by the count method. Light's Kappa was 0.664 for observation by the assessment method and 0.649 by the count method. The ICC was 0.82 (95% CI: 0.77-0.86) by the assessment method vs. 0.84 (95% CI: 0.80-0.87) by the count method.

CONCLUSION

Although the study in general showed a moderate to good inter-observer agreement according to both ICC and Lights Kappa, still major discrepancies were identified in especially the mid-range of observations. Consequently, for now Ki67 estimation is not implemented in the DBCG treatment algorithm.

Neoadjuvant letrozole for postmenopausal estrogen receptor-positive, HER2-negative breast cancer patients, a study from the Danish Breast Cancer Cooperative Group (DBCG)

INTRODUCTION

Neoadjuvant endocrine treatment (NET) is a low-toxicity approach to achieve operability in locally advanced breast cancer, and to facilitate breast conservation in early breast cancer, particular in patients with highly estrogen receptor (ER) positive and HER2-negative disease. Here, we report the results obtained by neoadjuvant letrozole in patients with early breast cancer in a phase-II design.

MATERIAL AND METHODS

A total of 119 postmenopausal women with ER-positive, HER2-negative operable breast cancer were assigned to four months of neoadjuvant letrozole before definitive surgery. Sentinel node or diagnostic fine needle aspiration cytology procedure was performed prior to treatment and the women were assessed prior, at two months, and before surgery with clinical examination, mammography and ultrasonography. Surgical specimens were examined for pathological response. Primary outcome was pathological and clinical response.

RESULTS

The per protocol population consisted of 112 patients. Clinical response was evaluated in 109 patients and pathological response in 108. Overall a mean decrease in tumor size was 15% (p ≤ .0001). One patient had complete pathological response and 55% of patients had partial pathological response. ER at 100%, ductal subtype, tumor size below 2 cm and lymph node-negative status was significantly associated with a better response to NET and malignancy grade 3 with a poorer response to NET. One patient progressed during treatment and received neoadjuvant chemotherapy. Eight patients received adjuvant chemotherapy due to lack of response.

CONCLUSION

Neoadjuvant aromatase inhibitor therapy is an acceptable strategy in selected postmenopausal patients with ER-rich and HER2-negative early breast cancer with ductal histology and should be considered when chemotherapy either isn't indicated or feasible.

Mortality and recurrence rates among systemically untreated high risk breast cancer patients included in the DBCG 77 trials

BACKGROUND

Following loco-regional treatment for early breast cancer accurate prognostication is essential for communicating benefits of systemic treatment. The aim of this study was to determine time to recurrence and long-term mortality rates in high risk patients according to patient characteristics and subtypes as assigned by immunohistochemistry panels.

PATIENTS AND METHODS

In November 1977 through January 1983, 2862 patients with tumors larger than 5 cm or positive axillary nodes were included in the DBCG 77 trials. Archival tumor tissue from patients randomly assigned to no systemic treatment was analyzed for ER, PR, Ki67, EGFR and HER2. Intrinsic subtypes were defined as follows: Luminal A, ER or PR >0%, HER2-negative, PR >10% and Ki67 < 14%; Luminal B, ER or PR >0%, (PR ≤10% or HER2-positive or Ki67 ≥ 14%); HER2E, ER 0%, PR 0%, HER2 positive; Core basal, ER 0%, PR 0%, HER2 negative and EGFR positive. Multivariate categorical and fractional polynomials (MFP) models were used to construct prognostic subsets by clinicopathologic characteristics.

RESULTS

In a multivariate model, mortality rate was significantly associated with age, tumor size, nodal status, invasion, histological type and grade, as well as subtype classification.

CONCLUSIONS

With 35 years of follow-up, in this population of high-risk patients with no systemic therapy, no subgroup based on a composite prognostic score and/or molecular subtypes could be identified without excess mortality as compared to the background population.

The clinical database and implementation of treatment guidelines by the Danish Breast Cancer Cooperative Group in 2007-2016

BACKGROUND

Since 40 years, Danish Breast Cancer Cooperative Group (DBCG) has provided comprehensive guidelines for diagnosis and treatment of breast cancer. This population-based analysis aimed to describe the plurality of modifications introduced over the past 10 years in the national Danish guidelines for the management of early breast cancer. By use of the clinical DBCG database we analyze the effectiveness of the implementation of guideline revisions in Denmark.

METHODS

From the DBCG guidelines we extracted modifications introduced in 2007-2016 and selected examples regarding surgery, radiotherapy (RT) and systemic treatment. We assessed introduction of modifications from release on the DBCG webpage to change in clinical practice using the DBCG clinical database.

RESULTS

Over a 10-year period data from 48,772 patients newly diagnosed with malignant breast tumors were entered into DBCG's clinical database and 42,197 of these patients were diagnosed with an invasive carcinoma following breast conserving surgery (BCS) or mastectomy. More than twenty modifications were introduced in the guidelines. Implementations, based on prospectively collected data, varied widely; exemplified with around one quarter of the patients not treated according to a specific guideline within one year from the introduction, to an almost immediate full implantation.

CONCLUSIONS

Modifications of the DBCG guidelines were generally well implemented, but the time to full implementation varied from less than one year up to around five years. Our data is registry based and does not allow a closer analysis of the causes for delay in implementation of guideline modifications.

Association of tissue inhibitor of metalloproteinases-1 and Ki67 in estrogen receptor positive breast cancer

BACKGROUND

The role of tissue inhibitor of metalloproteinases-1 (TIMP-1) in estrogen receptor (ER) positive breast cancer remains to be fully elucidated. We evaluated TIMP-1 as a prognostic marker in patients treated with adjuvant tamoxifen and investigated TIMP-1s association with Ki67 and ER/progesterone receptor (PR)/human epidermal growth factor receptor 2 (HER2) profiles.

MATERIAL AND METHODS

TIMP-1 expression was evaluated by immunohistochemistry (IHC) on formalin fixed paraffin embedded primary tumor tissue in two independent cohorts comprised of 236 and 192 patients, respectively.

RESULTS

No differences in disease free survival (HR 0.98; 95% CI 0.63-1.53; p = 0.92) and overall survival (HR 0.94; 95% CI 0.63-1.43; p = 0.79) were observed according to TIMP-1 status. A significant negative association between TIMP-1 and Ki67 was identified (p = 0.015). TIMP-1 expression did not differ significantly according to ER/PR/HER2 profiles. When analyzed as separate variables PR and HER2 status tended to have a positive but non-significant association with TIMP-1 (PR: p = 0.08; OR 2.54; 95% CI 0.91-7.10, HER2: p = 0.08; OR 0.48; 95% CI 0.21-1.08) whereas ER status was not associated with TIMP-1 expression (p = 0.48; OR 0.68; 95% CI 0.23-1.99).

CONCLUSION

TIMP-1 does not appear to be prognostic in breast cancer patients receiving adjuvant tamoxifen. We identified a negative association between TIMP-1 and Ki67. We did not confirm our previous in vitro findings of a negative association between TIMP-1 and PR.

The miRNA-200 family and miRNA-9 exhibit differential expression in primary versus corresponding metastatic tissue in breast cancer

Metastases are the major cause of cancer-related deaths, but the mechanisms of the metastatic process remain poorly understood. In recent years, the involvement of microRNAs (miRNAs) in cancer has become apparent, and the objective of this study was to identify miRNAs associated with breast cancer progression. Global miRNA expression profiling was performed on 47 tumor samples from 14 patients with paired samples from primary breast tumors and corresponding lymph node and distant metastases using LNA-enhanced miRNA microarrays. The identified miRNA expression alterations were validated by real-time PCR, and tissue distribution of the miRNAs was visualized by in situ hybridization. The patients, in which the miRNA profile of the primary tumor and corresponding distant metastasis clustered in the unsupervised cluster analysis, showed significantly shorter intervals between the diagnosis of the primary tumor and distant metastasis (median 1.6 years) compared to those that did not cluster (median 11.3 years) (p<0.003). Fifteen miRNAs were identified that were significantly differentially expressed between primary tumors and corresponding distant metastases, including miR-9, miR-219-5p and four of the five members of the miR-200 family involved in epithelial-mesenchymal transition. Tumor expression of miR-9 and miR-200b were confirmed using in situ hybridization, which also verified higher expression of these miRNAs in the distant metastases versus corresponding primary tumors. Our results demonstrate alterations in miRNA expression at different stages of disease progression in breast cancer, and suggest a direct involvement of the miR-200 family and miR-9 in the metastatic process.

PIK3CA mutations, PTEN, and pHER2 expression and impact on outcome in HER2-positive early-stage breast cancer patients treated with adjuvant chemotherapy and trastuzumab

BACKGROUND

This study was conducted to determine the frequency of PIK3CA mutations and human epidermal growth factor receptor-2 (HER2) phosphorylation status (pHER2-Tyr1221/1222) and if PIK3CA, phosphatase and tensin homolog (PTEN), or pHER2 has an impact on outcome in HER2-positive early-stage breast cancer patients treated with adjuvant chemotherapy and trastuzumab.

PATIENTS AND METHODS

Two hundred and forty HER2-positive early-stage breast cancer patients receiving adjuvant treatment (cyclophosphamide 600 mg/m2, epirubicin 60 mg/m2, and fluorouracil 600 mg/m2) before administration of 1 year trastuzumab were assessable. PTEN and pHER2 expression were assessed by immunohistochemistry. PIK3CA mutations (exons 9 and 20) were determined by pyrosequencing.

RESULTS

Five-year overall survival (OS) and invasive disease-free survival were 87.8% and 81.0%, respectively. Twenty-six percent of patients had a PIK3CA mutation, 24% were PTEN low, 45% pHER2 high, and 47% patients had increased PI3K pathway activation (PTEN low and/or PIK3CA mutation). No significant correlations were observed between the clinicopathological variables and PIK3CA, PTEN, and pHER2 status. In both univariate and multivariate analyses, patients with PIK3CA mutations or high PI3K pathway activity had a significant worse OS [multivariate: hazard ratio (HR) 2.14, 95% confidence interval (CI) 1.01-4.51, P=0.046; and HR 2.35, 95% CI 1.10-5.04, P=0.03].

CONCLUSION

Patients with PIK3CA mutations or increased PI3K pathway activity had a significantly poorer survival despite adequate treatment with adjuvant chemotherapy and trastuzumab.

Activated HER-receptors in predicting outcome of ER-positive breast cancer patients treated with adjuvant endocrine therapy

The four human epidermal growth factor receptors (HER1-4) are involved in growth stimulation and may play a role in endocrine resistance. The receptors form dimers, leading to activation by mutual phosphorylation. Our purpose was to explore the role of the activated receptors (pHER1, pHER2, pHER3) in endocrine treated breast cancer in terms of co-expression and association with disease-free survival (DFS) in 1062 patients with ER-positive tumors. Furthermore, HER2 amplification was evaluated. We found positive associations between the phosphorylated receptors. pHER1 and pHER3 were co-expressed with one or two of the other activated receptors in 85% and 89% of tumors, respectively, whereas pHER2 was co-expressed with the other activated receptors in 54% of tumors. Except for HER2, which was associated with poor prognosis, none of the remaining markers were associated with DFS. However, frequent co-expression indicates a role of the other HER-family members in activation of HER2.

Quantitative proteomics of primary tumors with varying metastatic capabilities using stable isotope-labeled proteins of multiple histogenic origins

The development of metastasis is a complex, multistep process that remains poorly defined. To identify proteins involved in the colonization phase of the metastatic process, we compared the proteome of tumors derived from inoculation of a panel of isogenic human cancer cell lines with different metastatic capabilities into the mammary fat pad of immunodeficient mice. Using a protein standard generated by SILAC-labeling, a total of 675 proteins were identified and 30 were differentially expressed between at least two of the tumors. The protein standard contained the proteomes of seven cell lines from multiple histogenic origins and displayed superior features compared to standard super-SILAC. The expression of some proteins correlated with metastatic capabilities, such as myosin-9 (nonmuscle myosin II A) and L-lactate dehydrogenase A, while the expression of elongation factor tu correlated inversely to metastatic capabilities. The expression of these proteins was biochemically validated, and expression of myosin-9 in clinical breast cancer samples was further shown to be altered in primary tumors versus corresponding lymph node metastasis. Our study demonstrates an improved strategy for quantitative comparison of an unlimited number of tumor tissues, and provides novel insights into key proteins associated with the colonization phase of metastasis formation.

ESR1 gene status correlates with estrogen receptor protein levels measured by ligand binding assay and immunohistochemistry

The Estrogen Receptor (ER) is an established predictive marker for the selection of adjuvant endocrine treatment in early breast cancer. During the 1990s Immunohistochemistry (IHC) replaced cytosol based assays for determination of ER status. This study examined the association between ER protein level determined by two different methods and ESR1 gene copy number. From 289 primary high-risk breast cancer patients, randomized in the Danish Breast Cancer Cooperative Group (DBCG) 77C trial, results from cytosolic ER levels were available from ligand binding assays. Archival tumor tissue was retrieved from 257 patients. ESR1/CEN-6 ratio was analyzed successfully by Fluorescence In Situ Hybridization (FISH) in 220 (86%) patients. ESR1 amplification (ESR1/CEN-6 ≥ 2.00) was observed in 23% of the patients and ESR1 deletion (ESR1/CEN-6 < 0.80) was observed in 32%. Further, we identified ESR1 gain (ratio ESR1/CEN-6 from 1.30 to 1.99) in 19% of the patients. A positive correlation of ESR1 FISH with both ER-cytosol and ER IHC was found (p < 0.0001). Amplification and gain of the ESR1 gene are associated with higher ER protein content measured by ligand binding assay and a more intense nuclear staining by IHC compared to tumors with normal ESR1 gene status. Major variations in ER measured by ligand binding assay and IHC are observed within all ESR1 copy number subgroups and other mechanisms than gene copy number seem to contribute to the ER protein content in the tumors.

Effects of the change in cutoff values for human epidermal growth factor receptor 2 status by immunohistochemistry and fluorescence in situ hybridization: a study comparing conventional brightfield microscopy, image analysis-assisted microscopy, and interobserver variation

CONTEXT

New guidelines for HER2 testing have been introduced.

OBJECTIVES

To evaluate the difference in HER2 assessment after introduction of new cutoff levels for both immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) and to compare interobserver agreement and time to score between image analysis and conventional microscopy.

DESIGN

Samples from 150 patients with breast cancer were scored by 7 pathologists using conventional microscopy, with a cutoff of both 10% and 30% IHC-stained cells, and using automated microscopy with image analysis. The IHC results were compared individually and to HER2 status as determined by FISH, using both the approved cutoff of 2.0 and the recently introduced cutoff of 2.2.

RESULTS

High concordance was found in IHC scoring among the 7 pathologists. The 30% cutoff led to slightly fewer positive IHC observations. Introduction of a FISH equivocal zone affected 4% of the FISH scores. If cutoff for FISH is kept at 2.0, no difference in patient selection is found between the 10% and the 30% IHC cutoff. Among the 150 breast cancer samples, the new 30% IHC and 2.2 FISH cutoff levels resulted in one case without a firm diagnosis because both IHC and FISH were equivocal. Automated microscopy and image analysis-assisted IHC led to significantly better interobserver agreement among the 7 pathologists, with an increase in mean scoring time of only about 30 seconds per slide.

CONCLUSIONS

The change in cutoff levels led to a higher concordance between IHC and FISH, but fewer samples were classified as HER2 positive.

PIK3CA mutations may be discordant between primary and corresponding metastatic disease in breast cancer

PURPOSE

PIK3CA mutations are frequent in breast cancer and activate the PI3K/Akt pathway. Unexpectedly, PIK3CA mutation appears in general to be associated with better outcome. In a cohort of patients where both primary and metastatic lesions were available, the objective was to assess changes in PIK3CA mutations. We wished to discern whether selective pressures occur and the influence of PIK3CA mutation on time to recurrence.

EXPERIMENTAL DESIGN

Formalin-fixed paraffin-embedded tumor blocks were obtained from 104 patients with paired samples from primary tumors and corresponding asynchronous metastatic breast tumors. Samples were analyzed for PIK3CA mutations (exons 9 and 20) as well as immunohistochemical evaluation for PTEN, pAKT, Ki67, ER, and HER2.

RESULTS

PIK3CA mutation was detected in 45% of the primary tumors. Overall, there was a net gain in mutation in metastatic disease, to 53%; nonetheless, there were instances where metastases were wild type in patients with PIK3CA mutant primary tumors. Laser capture microdissection on a subset of cases revealed microheterogeneity for PIK3CA mutational status in the primary tumor. PIK3CA mutants overall showed a significantly longer time to first recurrence than wild type cases (P = 0.03).

CONCLUSION

PIK3CA mutations occur at high frequency in primary and metastatic breast cancer; these may not necessarily confer increased aggressiveness as mutants had a longer time to recurrence. Because PIK3CA status quite frequently changes between primary and metastatic disease, it emphasizes the necessity of assessing the PIK3CA status in the metastatic lesion for selection of PIK3CA inhibitor therapy.

[Fine needle aspiration cytology of mammography screening]

INTRODUCTION

In the year 2000 a quality assurance programme for the preoperative breast diagnostics was introduced in Denmark. The programme was based on the "European guidelines for quality assurance in breast cancer screening and diagnosis" where - among other measures - five cytological diagnostic classes were introduced. The aim of this study was to evaluate the quality assurance programme in a screening population to determine whether fine needle aspiration cytology (FNAC) as first choice remains a useful tool in the preoperative diagnostics, or if needle core biopsy should be the first-choice treatment.

MATERIAL AND METHODS

767 women had FNAC performed from a total of 783 lesions at the Mammography Clinic, University Hospital Odense. All FNACs were compared with the final histology diagnosis. Nine statistical parameters were calculated according to the European guidelines.

RESULTS

A total of 66% of the 783 FNACs had a malignant cytology diagnosis, which in 99% of the cases turned out to be the correct diagnosis. Four lesions were false positives all of which represented benign proliferative breast diseases. The surgical procedures in these cases were either excisional biopsy or lumpectomy. The values of eight of the nine mutually dependent statistical parameters of quality scored within the recommended threshold values. Specificity was the only parameter that fell outside the recommended threshold values.

CONCLUSION

Although specificity in our study is lower than recommended, we find that the use of FNAC as first-choice in triple diagnostics is a useful tool.

Metastasis-related plasma membrane proteins of human breast cancer cells identified by comparative quantitative mass spectrometry

The spread of cancer cells from a primary tumor to form metastasis at distant sites is a complex multistep process. The cancer cell proteins and plasma membrane proteins in particular involved in this process are poorly defined, and a study of the very early events of the metastatic process using clinical samples or in vitro assays is not feasible. We have used a unique model system consisting of two isogenic human breast cancer cell lines that are equally tumorigenic in mice; but although one gives rise to metastasis, the other disseminates single cells that remain dormant at distant organs. Membrane purification and comparative quantitative LC-MS/MS proteomics identified 13 membrane proteins that were expressed at higher levels and three that were underexpressed in the metastatic compared with the non-metastatic cell line from a total of 1919 identified protein entries. Among the proteins were ecto-5'-nucleotidase (CD73), NDRG1, integrin beta1, CD44, CD74, and major histocompatibility complex class II proteins. The altered expression levels of proteins identified by LC-MS/MS were validated using flow cytometry, Western blotting, and immunocyto- and immunohistochemistry. Analysis of clinical breast cancer biopsies demonstrated a significant correlation between high ecto-5'-nucleotidase and integrin beta1 expression and poor outcome, measured as tumor spread or distant recurrence within a 10-year follow-up. Further the tissue analysis suggested that NDRG1, HLA-DRalpha, HLA-DRbeta, and CD74 were associated with the ER(-)/PR(-) phenotype represented by the two cell lines. The study demonstrates a quantitative and comparative proteomics strategy to identify clinically relevant key molecules in the early events of metastasis, some of which may prove to be potential targets for cancer therapy.

Determination of HER2 phosphorylation at tyrosine 1221/1222 improves prediction of poor survival for breast cancer patients with hormone receptor-positive tumors

INTRODUCTION

High expression of total HER2 protein confers poor prognosis for breast cancer patients. HER2 is a member of the HER family consisting of four receptors, HER1 to HER4. HER receptor activity is regulated by a variety of mechanisms, and phosphorylation of the C-terminal part of the HER receptors is a marker for active signaling. The importance of phosphorylation and thereby activation of the HER1 to HER4 receptors, however, has not been investigated concomitantly in breast tumors. In the present study we examined the importance of active HER signaling in breast tumor biopsies and paired metastases, by evaluating the expression of phosphorylated HER1, HER2, HER3, Erk, Akt and the total level of HER4 and HER2.

METHODS

Immunohistochemical analysis was performed on 268 primary breast tumors and 30 paired metastatic lesions from postmenopausal women with hormone receptor-positive breast tumors, who had received adjuvant tamoxifen therapy. The observed protein expression levels were analyzed for co-expression, for correlation to clinicopathological parameters and for prognostic value in relation to disease-free survival and overall survival. Lastly, the difference between protein levels in primary tumors versus metastasis was evaluated.

RESULTS

In the primary tumors, 8%, 18%, 14% and 15% of cases were scored positive for total HER2, pHER1, pHER2 and pHER3 expression, respectively. HER4 was expressed with strong intensity in 68% and at moderate intensity in 29% of cases. The activated forms of Akt and Erk were quite uniformly expressed in the categories; negative, moderate or strong. In univariate analysis, expression of total HER2, pHER1, pHER2 and pHER3 was significantly associated with poor disease-free survival. Strong HER4 expression was associated with prolonged disease-free as well as with overall survival. Expression of pAkt and pErk was not correlated with survival. In multivariate analysis, pHER2 expression was clearly an independent marker for poor disease-free survival and overall survival when tested against tumor size, tumor grade, nodal status and HER2. Lastly, comparison of HER receptor expression in metastatic versus primary tumors showed a significant increase in expression of pHER1 and pHER3 in the metastases.

CONCLUSIONS

In hormone receptor-positive breast cancer, determination of pHER2 yields additional prognostic information about poor prognosis compared with the current clinical standard for measuring HER2.