Impact of estrogen receptor levels on outcome in non-metastatic triple negative breast cancer patients treated with neoadjuvant/adjuvant chemotherapy

Efficacy and feasibility of neoadjuvant pembrolizumab plus chemotherapy for early-stage triple-negative and estrogen receptor low, HER2-negative breast cancer: a Japanese single-institution real-world study

BACKGROUND

Neoadjuvant pembrolizumab plus chemotherapy and adjuvant pembrolizumab have been established as the optimal systemic therapies for patients with early stage triple-negative breast cancer (TNBC); however, their efficacy and feasibility in the Japanese population remain unexplored.

METHODS

This study included patients with early stage TNBC or low estrogen receptor (ER) positivity (1-9%) with human epidermal growth factor receptor type 2- (HER2-) negative breast cancer who received neoadjuvant pembrolizumab plus chemotherapy from October 2022 at Cancer Institute Hospital of Japanese Foundation for Cancer Research. Information regarding clinicopathological features, systemic therapy, treatment outcomes, and adverse events of patients who underwent surgery by February 2024 was retrospectively collected.

RESULTS

Overall, 69 patients received neoadjuvant pembrolizumab plus carboplatin and paclitaxel therapy, and 46 underwent surgery by February 2024. The median age of the patients was 53.5 years, and 80.4% and 19.6% had stage II and III disease, respectively. TNBC and ER-low HER2-negative breast cancer accounted for 82.6% and 17.4% cases, respectively. Overall pathological complete response rate was 56.5%, with 87.5% in patients with ER-low HER2-negative tumors. The completion rates for neoadjuvant pembrolizumab, chemotherapy, and pembrolizumab plus chemotherapy were 65.2%, 56.5%, and 52.2%, respectively. Furthermore, 80.4% and 15.2% of patients experienced grade 3 or higher treatment-related adverse events and immune-related adverse events, respectively, and 34% experienced unexpected hospitalization during neoadjuvant treatment.

CONCLUSIONS

The efficacy and safety profiles of neoadjuvant pembrolizumab plus chemotherapy in the Japanese population are consistent with previous reports. This regimen may have therapeutic potential against ER-low HER2-negative tumors and TNBC.

Expression and Subtype Discordance Between Core Needle Biopsy and Surgical Specimen in Breast Cancer

INTRODUCTION

Estrogen receptors (ERs), progesterone receptors (PRs), and human epidermal growth factor receptors 2 (HER2s) are crucial for the molecular subtype classification and therapy decision-making in breast cancer. Core needle biopsy (CNB) serves as an essential preoperative diagnostic tool for biomarker evaluation, offering minimal invasiveness and convenience. However, CNB has limitations including insufficient sampling volume, sampling errors, underestimation and false results. This study evaluated the discordance of ER, PR, HER2, and molecular subtype between CNB and surgical specimen (SS) in breast cancer, explored the factors associated with discordance and discussed which specific breast cancer cases were recommended for retesting.

MATERIALS AND METHODS

Medical records of invasive breast cancer patients admitted to Fujian Medical University Union Hospital from January 2014 to January 2020 were retrospectively collected. Immunohistochemistry and fluorescence in situ hybridization were used to assess the status of ER, PR, and HER2 in both CNB and SS. The agreement analyses were performed using the Kappa test. Univariable and multivariable logistic regressions were employed to identify factors associated with discordance of biomarkers and molecular subtypes.

RESULTS

A total of 2099 patients were included in the study. Discordance rates were 3.9% (n = 82) for the ER, 4.8% (n = 101) for PR and 1.2% (n = 25) for HER2. High agreement was observed between CNB and SS for ER (κ=0.899), PR (κ=0.896) and HER2 (κ=0.972). There were 344 cases of molecular typing discordance, with the majority (n = 226, 65.7%) occurring between Luminal A and Luminal B (HER2-). Factors of ER discordance were large tumor size (OR = 8.715, P < 0.001), ER-low biopsy status (OR = 49.959, P < 0.001) and PR-high biopsy status (OR = 0.046, P < 0.001. Factors of molecular subtype discordance were carcinoma in situ (OR = 1.930, P = 0.007), ER-low biopsy status (OR = 40.527, P < 0.001) and Ki67-high biopsy status (OR = 0.332, P < 0.001).

CONCLUSIONS

CNB showed good accuracy in evaluating ER, PR, HER2, and molecular subtypes in breast cancer. However, concerning the factors associated with discordance, we recommend retesting for three CNB cases (1) ER-negative and PR-positive, (2) ER low-expression and PR-negative, and (3) Luminal A subtype with tumors ≤2 cm, which might offer a valuable reference for clinical decision-making.

Reassessing estrogen receptor expression thresholds for breast cancer prognosis in HER2-negative patients using shape restricted modeling

We used a novel shape-restricted Cox model to determine the desirable ER expression cutoff to predict breast cancer prognoses. Our model treats ER as a continuous variable using a flexible monotone-shaped Cox regression to assess its association with survival outcomes holistically. The study included 3055 patients with stage II/III HER2-negative breast cancer. The primary outcomes were time to recurrence or death (TTR) and overall survival (OS). The shape-restricted Cox model identified 10% ER as the preferred cutoff to predict TTR. The finding was confirmed by the log-rank test and standard Cox model that patients with ER ≥ 10% had TTR benefit over ER < 10% (log-rank p < 0.001). No OS or TTR benefit of adjuvant endocrine therapy was observed in patients with 1% ≤ ER < 10% (HR 0.877, 95% CI 0.481-1.600, p = 0.668 for TTR and HR 0.698, 95% CI 0.337-1.446, p = 0.333 for OS). Using the shape-restricted Cox model, this study suggests a potential preferred threshold of 10% for predicting TTR. The findings could assist physicians in effectively weighing the benefits and risks of adjuvant endocrine therapy for patients with ER < 10% disease, particularly in cases involving severe adverse events.

TROPION-Breast04: a randomized phase III study of neoadjuvant datopotamab deruxtecan (Dato-DXd) plus durvalumab followed by adjuvant durvalumab versus standard of care in patients with treatment-naïve early-stage triple negative or HR-low/HER2- breast cancer

Background

Despite treatment advances for patients with early-stage triple-negative breast cancer (TNBC) and hormone receptor (HR)-low/human epidermal growth factor receptor 2-negative (HER2-) breast cancer, treatments that improve clinical outcomes while mitigating toxicity are needed. Datopotamab deruxtecan (Dato-DXd), a TROP2-directed antibody-drug conjugate consisting of a humanized IgG1 monoclonal antibody attached via a plasma-stable cleavable linker to a topoisomerase-I inhibitor payload, has shown efficacy alone or in combination with durvalumab, a selective, high-affinity anti-programmed cell death ligand 1 antibody, in early-phase clinical studies.

Objectives

The primary objective of TROPION-Breast04 is to evaluate the efficacy and safety of neoadjuvant Dato-DXd plus durvalumab followed by adjuvant durvalumab with or without chemotherapy versus standard of care in patients with previously untreated early-stage TNBC or HR-low/HER2- breast cancer.

Design

This is an ongoing, international, phase III, open-label, randomized controlled study.

Methods and analysis

Approximately 1728 patients (aged ⩾18 years) will be randomized 1:1 to eight cycles of neoadjuvant Dato-DXd (6 mg/kg intravenously (IV) every 3 weeks (Q3W)) plus durvalumab (1120 mg IV Q3W) followed by nine cycles of adjuvant durvalumab (1120 mg IV Q3W) with or without chemotherapy versus eight cycles of pembrolizumab (200 mg IV Q3W) plus chemotherapy followed by nine cycles of adjuvant pembrolizumab (200 mg IV Q3W) with or without chemotherapy. Dual primary endpoints are pathological complete response by blinded central review and event-free survival by investigator assessment. Secondary endpoints include overall survival (key), distant disease-free survival, patient-reported outcomes, and safety.

Ethics

The study is approved by independent ethics committees and/or institutional review boards at each study site. All patients will provide written informed consent.

Discussion

This study will evaluate the potential use of neoadjuvant Dato-DXd plus durvalumab followed by adjuvant durvalumab with or without chemotherapy versus standard of care in patients with previously untreated early-stage TNBC or HR-low/HER2- breast cancer. The findings of this trial could lead to promising treatment options for these patients.

Trial registration

ClinicalTrials.gov identifier: NCT06112379.

Kinome-Focused CRISPR-Cas9 Screens in African Ancestry Patient-Derived Breast Cancer Organoids Identify Essential Kinases and Synergy of EGFR and FGFR1 Inhibition

Precision medicine approaches to cancer treatment aim to exploit genomic alterations that are specific to individual patients to tailor therapeutic strategies. Yet, some targetable genes and pathways are essential for tumor cell viability even in the absence of direct genomic alterations. In underrepresented populations, the mutational landscape and determinants of response to existing therapies are poorly characterized because of limited inclusion in clinical trials and studies. One way to reveal tumor essential genes is with genetic screens. Most screens are conducted on cell lines that bear little resemblance to patient tumors, after years of culture under nonphysiologic conditions. To address this problem, we aimed to develop a CRISPR screening pipeline in three-dimensionally grown patient-derived tumor organoid (PDTO) models. A breast cancer PDTO biobank that focused on underrepresented populations, including West African patients, was established and used to conduct a negative-selection kinome-focused CRISPR screen to identify kinases essential for organoid growth and potential targets for combination therapy with EGFR or MEK inhibitors. The screen identified several previously unidentified kinase targets, and the combination of FGFR1 and EGFR inhibitors synergized to block organoid proliferation. Together, these data demonstrate the feasibility of CRISPR-based genetic screens in patient-derived tumor models, including PDTOs from underrepresented patients with cancer, and identify targets for cancer therapy. Significance: Generation of a breast cancer patient-derived tumor organoid biobank focused on underrepresented populations enabled kinome-focused CRISPR screening that identified essential kinases and potential targets for combination therapy with EGFR or MEK inhibitors. See related commentary by Trembath and Spanheimer, p. 407.

Beyond Hormone Receptors: liquid biopsy tools to unveil new clinical meanings and empower therapeutic decision-making in Luminal-like metastatic breast cancer

Immunohistochemical (IHC) tissue profiling is a standard practice in the management of metastatic breast cancer (mBC), that enables the identification of distinct biological phenotypes based on hormone receptors' expression. Luminal-like tumors primarily benefit from a first line treatment strategy combining endocrine therapy and cyclin-dependent kinase 4/6 inhibitors. However, IHC analyses necessitate invasive procedures and may encounter technical and interpretational challenges. In the current era of precision medicine, liquid biopsy holds potential to provide clinicians with additional insights into disease biology, including mechanisms underlying endocrine resistance and disease progression. Several liquid-based biomarkers are entering clinical practice and hold prognostic and predictive values in Luminal-like mBC, while many others are currently being investigated. The present work aims to summarize the current evidence regarding the clinical meanings of hormone receptors and their downstream molecular pathways, alongside their implications for therapeutic decision-making in Luminal-like mBC.

Molecular Basis of Breast Tumor Heterogeneity

Breast cancer (BC) is a profoundly heterogenous disease, with diverse molecular, histological, and clinical variations. The intricate molecular landscape of BC is evident even at early stages, illustrated by the complexity of the evolution from precursor lesions to invasive carcinoma. The key for therapeutic decision-making is the dynamic assessment of BC receptor status and clinical subtyping. Hereditary BC adds an additional layer of complexity to the disease, given that different cancer susceptibility genes contribute to distinct phenotypes and genomic features. Furthermore, the various BC subtypes display distinct metabolic demands and immune microenvironments. Finally, genotypic-phenotypic correlations in special histologic subtypes of BC inform diagnostic and therapeutic approaches, highlighting the significance of thoroughly comprehending BC heterogeneity.

Immune and gene-expression profiling in estrogen receptor low and negative early breast cancer

BACKGROUND

The cutoff of <1% positive cells to define estrogen receptor (ER) negativity by immunohistochemistry (IHC) in breast cancer (BC) is debated. We explored the tumor immune microenvironment and gene-expression profile of patients with early-stage HER2-negative ER-low (ER 1%-9%) BC, comparing them to ER-negative (ER <1%) and ER-intermediate (ER 10%-50%) tumors.

METHODS

Among 921 patients with early-stage I-III, ER ≤50%, HER2-negative BCs, tumors were classified as ER-negative (n = 712), ER-low (n = 128), or ER-intermediate (n = 81). Tumor-infiltrating lymphocytes (TILs) were evaluated. CD8+, FOXP3+ cells, and PD-L1 status were assessed by IHC and quantified by digital pathology. We analyzed 776 BC-related genes in 116 samples. All tests were 2-sided at a <.05 significance level.

RESULTS

ER-low and ER-negative tumors exhibited similar median TILs, statistically significantly higher than ER-intermediate tumors. CD8/FOXP3 ratio and PD-L1 positivity rates were comparable between ER-low and ER-negative groups. These groups showed similar enrichment in basal-like intrinsic subtypes and comparable expression of immune-related genes. ER-low and ER-intermediate tumors showed significant transcriptomic differences. High TILs (≥30%) were associated with improved relapse-free survival (RFS) in ER-low (5-year RFS 78.6% vs 66.2%, log-rank P = .033, hazard ratio [HR] 0.37 [95% CI = 0.15 to 0.96]) and ER-negative patients (5-year RFS 85.2% vs 69.8%, log-rank P < .001, HR 0.41 [95% CI = 0.27 to 0.60]).

CONCLUSIONS

ER-low and ER-negative tumors are similar biological and molecular entities, supporting their comparable clinical outcomes and treatment responses, including to immunotherapy. Our findings contribute to the growing evidence calling for a reevaluation of ER-positive BC classification and management, aligning ER-low and ER-negative tumors more closely.

The "lows": Update on ER-low and HER2-low breast cancer

ER-low and HER2-low breast cancers have emerged as clinically significant subtypes that challenge traditional diagnostic categories and treatment paradigms. These subtypes, representing a spectrum of disease, exhibit distinct biological behaviors, therapeutic responses, and prognostic outcomes. HER2-low breast cancer, defined by low HER2 protein expression (IHC score of 1+ or 2+ without HER2 gene amplification), has achieved clinical significance, particularly following the DESTINY-Breast trials, which demonstrated the efficacy of trastuzumab deruxtecan (T-DXd) in the population of patients with advanced HER2-low disease. Similarly, ER-low breast cancer, characterized by low estrogen receptor expression (in 1%-10 % invasive tumor cells), poses unique challenges due to its intermediate biological behavior and uncertain response to endocrine therapies. The identification of these subtypes is further complicated by inconsistencies in testing methodologies, which can lead to misclassification and impact treatment decisions. As our understanding of these subtypes improves, the need for standardized diagnostic approaches and individualized therapeutic decisions becomes increasingly urgent. Ongoing research and collaboration between pathologists and oncologists are essential for refining diagnostic criteria and improving outcomes for patients with breast cancers characterized by low expression of these theragnostic biomarkers. This review aims to consolidate current knowledge on HER2-low and ER-low breast cancers, focusing on the challenges associated with their identification, the implications for treatment, and future directions in clinical management. By examining recent studies and interlaboratory assessments, this review emphasizes the critical need for accurate and reproducible testing and reporting, and for the development of tailored therapeutic strategies for these "low" expression cancers.

Predicting pathologic complete response to neoadjuvant chemotherapy in breast cancer using a machine learning approach

BACKGROUND

For patients with breast cancer undergoing neoadjuvant chemotherapy (NACT), most of the existing prediction models of pathologic complete response (pCR) using clinicopathological features were based on standard statistical models like logistic regression, while models based on machine learning mostly utilized imaging data and/or gene expression data. This study aims to develop a robust and accessible machine learning model to predict pCR using clinicopathological features alone, which can be used to facilitate clinical decision-making in diverse settings.

METHODS

The model was developed and validated within the National Cancer Data Base (NCDB, 2018-2020) and an external cohort at the University of Chicago (2010-2020). We compared logistic regression and machine learning models, and examined whether incorporating quantitative clinicopathological features improved model performance. Decision curve analysis was conducted to assess the model's clinical utility.

RESULTS

We identified 56,209 NCDB patients receiving NACT (pCR rate: 34.0%). The machine learning model incorporating quantitative clinicopathological features showed the best discrimination performance among all the fitted models [area under the receiver operating characteristic curve (AUC): 0.785, 95% confidence interval (CI): 0.778-0.792], along with outstanding calibration performance. The model performed best among patients with hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) breast cancer (AUC: 0.817, 95% CI: 0.802-0.832); and by adopting a 7% prediction threshold, the model achieved 90.5% sensitivity and 48.8% specificity, with decision curve analysis finding a 23.1% net reduction in chemotherapy use. In the external testing set of 584 patients (pCR rate: 33.4%), the model maintained robust performance both overall (AUC: 0.711, 95% CI: 0.668-0.753) and in the HR+/HER2- subgroup (AUC: 0.810, 95% CI: 0.742-0.878).

CONCLUSIONS

The study developed a machine learning model ( https://huolab.cri.uchicago.edu/sample-apps/pcrmodel ) to predict pCR in breast cancer patients undergoing NACT that demonstrated robust discrimination and calibration performance. The model performed particularly well among patients with HR+/HER2- breast cancer, having the potential to identify patients who are less likely to achieve pCR and can consider alternative treatment strategies over chemotherapy. The model can also serve as a robust baseline model that can be integrated with smaller datasets containing additional granular features in future research.

A population-based study on trajectories of HER2 status during neoadjuvant chemotherapy for early breast cancer and metastatic progression

BACKGROUND

This study aimed to investigate the distribution and changes of HER2 status in untreated tumours, in residual disease and in metastasis, and their long-term prognostic implications.

METHODS

This is a population-based cohort study of patients treated with neoadjuvant chemotherapy for breast cancer during 2007-2020 in the Stockholm-Gotland region which comprises 25% of the entire Swedish population. Information was extracted from the National Breast Cancer Registry and electronic patient charts to minimize data missingness and misclassification.

RESULTS

In total, 2494 patients received neoadjuvant chemotherapy, of which 2309 had available pretreatment HER2 status. Discordance rates were 29.9% between primary and residual disease (kappa = 0.534), 31.2% between primary tumour and metastasis (kappa = 0.512) and 33.3% between residual disease to metastasis (kappa = 0.483). Adjusted survival curves differed between primary HER2 0 and HER2-low disease (p < 0.001), with the former exhibiting an early peak in risk for death which eventually declined below the risk of HER2-low. Across all disease settings, increasing the number of biopsies increased the likelihood of detecting HER2-low status.

CONCLUSION

HER2 status changes during neoadjuvant chemotherapy and metastatic progression, and the long-term behaviours of HER2 0 and HER2-low disease differ, underscoring the need for obtaining tissue biopsies and for extended follow-up in breast cancer studies.

MRI features of breast cancer immunophenotypes with a focus on luminal estrogen receptor low positive invasive carcinomas

To compare the magnetic resonance imaging (MRI) features of different immunophenotypes of breast carcinoma of no special type (NST), with special attention to estrogen receptor (ER)-low-positive breast cancer. This retrospective, single-centre, Institutional Review Board (IRB)-approved study included 398 patients with invasive breast carcinoma. Breast carcinomas were classified as ER-low-positive when there was ER staining in 1-10% of tumour cells. Pretreatment MRI was reviewed to assess the tumour imaging features according to the 5th edition of the Breast Imaging Reporting and Data System (BI-RADS) lexicon. Of the 398 cases, 50 (12.6%) were luminal A, 191 (48.0%) were luminal B, 26 (6.5%) were luminal ER-low positive, 64 (16.1%) were HER2-overexpressing, and 67 (16.8%) were triple negative. Correlation analysis between MRI features and tumour immunophenotype showed statistically significant differences in mass shape, margins, internal enhancement and the delayed phase of the kinetic curve. An oval or round shape and rim enhancement were most frequently observed in triple-negative and luminal ER-low-positive tumours. Spiculated margins were most common in luminal A and luminal B tumours. A persistent kinetic curve was more frequent in luminal A tumours, while a washout curve was more common in the triple-negative, HER2-overexpressing and luminal ER-low-positive immunophenotypes. Multinomial regression analysis showed that luminal ER-low-positive tumours had similar results to triple-negative tumours for almost all variables. Luminal ER-low-positive tumours present with similar MRI findings to triple-negative tumours, which suggests that MRI can play a fundamental role in adequate radiopathological correlation and therapeutic planning in these patients.

Deep learning for automated scoring of immunohistochemically stained tumour tissue sections - Validation across tumour types based on patient outcomes

We aimed to develop deep learning (DL) models to detect protein expression in immunohistochemically (IHC) stained tissue-sections, and to compare their accuracy and performance with manually scored clinically relevant proteins in common cancer types. Five cancer patient cohorts (colon, two prostate, breast, and endometrial) were included. We developed separate DL models for scoring IHC-stained tissue-sections with nuclear, cytoplasmic, and membranous staining patterns. For training, we used images with annotations of cells with positive and negative staining from the colon cohort stained for Ki-67 and PMS2 (nuclear model), the prostate cohort 1 stained for PTEN (cytoplasmic model) and β-catenin (membranous model). The nuclear DL model was validated for MSH6 in the colon, MSH6 and PMS2 in the endometrium, Ki-67 and CyclinB1 in prostate, and oestrogen and progesterone receptors in the breast cancer cohorts. The cytoplasmic DL model was validated for PTEN and Mapre2, and the membranous DL model for CD44 and Flotillin1, all in prostate cohorts. When comparing the results of manual and DL scores in the validation sets, using manual scores as the ground truth, we observed an average correct classification rate of 91.5 % (76.9-98.5 %) for the nuclear model, 85.6 % (73.3-96.6 %) for the cytoplasmic model, and 78.4 % (75.5-84.3 %) for the membranous model. In survival analyses, manual and DL scores showed similar prognostic impact, with similar hazard ratios and p-values for all DL models. Our findings demonstrate that DL models offer a promising alternative to manual IHC scoring, providing efficiency and reproducibility across various data sources and markers.

Real-World Data on Pathological Response and Survival Outcomes After Neoadjuvant Chemotherapy in HER2-Low Breast Cancer Patients

BACKGROUND

Data on the pathological responses and survival outcomes after neoadjuvant chemotherapy (NACT) in human epidermal growth factor receptor-2 (HER2)-low breast cancer (BC) are lacking. This study aims to investigate this topic in the real world.

METHODS

Clinicopathological data from 819 HER2-negative BC patients who underwent NACT between 2010 and 2020 were retrospectively retrieved from the Shanghai Jiaotong University Breast Cancer Database. These patients were categorized into HER2-low and HER2-0 groups. Logistic analyses were conducted to identify predictors of complete pathological response (pCR) and breast pCR. Cox regression analyses were conducted to assess the factors associated with disease-free survival (DFS) and overall survival (OS). Kaplan-Meier (K-M) curves were generated to compare DFS and OS between HER2-low BC and HER2-0 BC.

RESULTS

Of the 819 BC patients, 669 (81.7%) had HER2-low tumors, and 150 (18.3%) had HER2-0 tumors. HER2-low BC had a significantly higher ratio of ER ≥ 10%, PR ≥ 20%, and Ki67 ≥ 15% than HER2-0 BC. A significantly higher breast pCR rate was observed in HER2-low BC than in HER2-0 BC (13.6% and 7.3%, respectively, P = .036). Age, HER2 status (low or 0), Ki67, and surgery options were associated with breast pCR in HER2-negative BC. In HER2-low BC, the pCR rate of ER ≥ 10% BC was significantly lower than that of ER < 10% BC, but the DFS and OS of ER 10% BC were significantly higher. The K-M curve showed no significant differences in DFS or OS between HER2-low and HER2-0 BC. Cox regression revealed that ER expression and histological grade (III vs. I∼II) were significantly associated with survival in HER2-low BC.

CONCLUSIONS

In this real-world data (RWD) study, a significantly higher breast pCR rate was found in HER2-low BC than in HER2-0 BC, although there was no significant difference in survival. Moreover, ER expression had a significant prognostic impact on HER2-low BC.

Navigating practical challenges in immunotherapy for metastatic triple negative breast cancer

Immunotherapy has revolutionized cancer therapy and now represents a standard of care for many tumor types, including triple-negative breast cancer. Despite the positive results that have led to the approval of immunotherapy in both early- and advanced-stage triple-negative breast cancer, pivotal clinical trials cannot address the myriad questions arising in everyday clinical practice, often falling short in delivering all the information that clinicians require. In this manuscript, we aim to address some of these practical questions, with the purpose of providing clinicians with a guide for optimizing the use of immune checkpoint inhibitors in the management of breast cancer patients and identifying opportunities for future research to clarify unresolved questions.

Is Oncotype DX testing informative for breast cancers with low ER expression? A retrospective review from a biomarker testing referral center

PURPOSE

It remains unclear whether patients with HER2-negative, low-estrogen receptor (ER-low)-positive early breast cancer (BC) benefit from Oncotype DX® (ODX) testing.

METHODS

We conducted a retrospective review of cases referred for ODX testing over a seven-year period from a breast biomarker testing referral center (n = 854). For each case, we recorded the ODX Recurrence Score (RS) along with percentage of ER nuclear positivity and staining intensity on immunohistochemistry. Our criteria for ER-low was defined as ≤10% cells with nuclear positivity and/or weak intensity of staining. Slides from all ER-low cases were reviewed and the reported ODX ER gene scores were recorded. We randomly selected a comparator group of 56 patients with ER > 10% positivity and non-weak staining intensity (ER-high).

RESULTS

We identified 27 cases (3.2%) that met our criteria for ER-low. Of these, 92.6% had a high RS (>25), and 7.4% had a RS of 25. All cases with ≤10% ER nuclear positivity had a high RS. Most ER-low cases (85.2%) had ODX quantitative ER gene scores in the negative range, whereas all (100%) ER-high cases had positive ER gene scores.

CONCLUSION

ODX does not appear to add significant additional information to inform treatment decisions for most patients with ER-low BC. Incorporating weak ER staining intensity in addition to low percentage of nuclear positivity identifies about twice as many ER-low patients, although with reduced specificity for high RS. Our study supports the contention that most ER-low early BC should be regarded similarly to ER-negative BC.

Real-world overall survival and characteristics of patients with ER-zero and ER-low HER2-negative breast cancer treated as triple-negative breast cancer: a Swedish population-based cohort study

Background

Estrogen receptor-low (ER-low) HER2-negative breast cancer has similar pathological and molecular characteristics as triple-negative breast cancer (TNBC), and it is questionable whether it should be considered a separate entity. When the international guidelines lowered the cutoff for ER positivity to ≥1% in 2010, the ≥10% threshold was kept in Sweden. ER-low breast cancer (ER 1-9%) is thus in Sweden treated as TNBC. We aimed to describe patient and tumor characteristics, treatment patterns and overall survival in a Swedish population-based cohort of patients with ER-zero and ER-low HER2-negative breast cancer treated as TNBC.

Methods

All TNBC cases diagnosed in Sweden 2008-2020 were included in a population-based cohort study. Patient, tumor and treatment characteristics were analyzed by ER-status (ER 0% vs 1-9%), and associations between subgroups compared using χ2 test. Survival endpoint was overall survival (OS), and Kaplan-Meier curves were estimated. Cox proportional hazards models were used to estimate adjusted hazard ratios comparing ER-low to ER-zero.

Findings

Of the 5655 tumors, 90.1% had an ER expression of 0%, while 9.9% were ER-low. ER-low tumors were grade III in 69.4% (80.8% in ER-zero tumors, p-value = 0.001), with a median Ki67 of 60% (63% in ER-zero tumors, p-value = 0.005). There were no significant differences in given chemotherapy (p = 0.546). A pathological complete response (pCR) was achieved in 28.1% of ER-low tumors (25.1% in ER-zero tumors). In the unadjusted analysis of OS, women with ER-low disease had a borderline but not significantly better OS than those with ER-zero disease (HR 0.84 (95% CI 0.71-1.00), p = 0.052). ER-status 1-9% vs 0% was not associated with OS in the multivariable analysis (HR 1.11 (0.90-1.36)). Distant disease-free survival did not differ by ER-status 0% vs 1-9% (HR 0.97 for ER-zero vs ER-low (0.62-1.53), p = 0.905). After preoperative treatment, the impact of pCR for OS did not significantly differ between ER-zero or ER-low disease.

Interpretation

ER-low HER2-negative breast cancer has characteristics and prognosis similar to TNBC, when treated in the same way. Therefore, it seems reasonable to use a ≥10% threshold for ER positivity. This would provide patients with ER-low tumors the same treatment opportunities as patients with TNBC, within studies and within clinical routine.

Funding

This work was financially supported by Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA, in accordance with terms and conditions of a Master Collaboration Agreement between the company and Karolinska Institutet.

Comparison of cisplatin-based versus standard preoperative chemotherapy in patients with operable triple-negative breast cancer: propensity score matching and inverse probability of treatment weighting analysis

PURPOSE

The efficacy of carboplatin is non-equivalent to that of cisplatin (CDDP) for various tumor types in curative settings. However, the role of CDDP in operable triple-negative breast cancer (TNBC) patients remains unknown. We conducted a multicenter observational study to examine the effects of CDDP added to preoperative chemotherapy in patients with TNBC.

METHODS

This retrospective study consecutively included previously untreated patients with stage I-III TNBC treated with preoperative chemotherapy with or without CDDP. The primary endpoint was distant disease-free survival (DDFS). Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were used to minimize confounding biases in comparisons between the two groups.

RESULTS

A total of 138 patients were enrolled in the study. Of these, 52 were in the CDDP group and 86 in the non-CDDP group. DDFS was significantly better in the CDDP group than in the non-CDDP group (unadjusted hazard ratio (HR) 0.127 and p < 0.001, PSM HR 0.141 and p < 0.003, IPTW HR 0.123 and p =  < 0.001). Furthermore, among the patients with residual cancer burden (RCB) class II/III, DDFS was better in the CDDP group than in the non-CDDP group (unadjusted HR 0.192 and p = 0.013, PSM HR 0.237 and p = 0.051, IPTW HR 0.124 and p = 0.059).

CONCLUSION

Our study showed that CDDP-containing regimens achieved favorable prognoses in patients with operable TNBC, especially for the RCB class II/III population. Confirmative studies are warranted to elucidate the role of CDDP in TNBC treatment.

FOXC1 and SOX10 in Estrogen Receptor-Low Positive/HER2-Negative Breast Cancer: Potential Biomarkers for the Basal-like Phenotype Prediction

CONTEXT.—

Breast cancer with low (1%-10%) estrogen receptor (ER) expression (ER-low positive) constitutes a small portion of invasive breast cancers, and the treatment strategy for these tumors remains debatable.

OBJECTIVE.—

To characterize the features and outcomes of ER-low positive patients, and clarify the clinical significance of FOXC1 and SOX10 expression in ER-low positive/HER2-negative tumors.

DESIGN.—

Among 9082 patients diagnosed with primary invasive breast cancer, the clinicopathologic features of those with ER-low positive breast cancer were characterized. FOXC1 and SOX10 mRNA levels were analyzed in ER-low positive/HER2-negative cases from public data sets. The expression of FOXC1 and SOX10 in ER-low positive/HER2-negative tumors was evaluated by immunohistochemistry.

RESULTS.—

The clinicopathologic study of ER-low positive tumors indicated more aggressive characteristics compared with those tumors with ER >10%, while they had more overlapping features with ER-negative tumors irrespective of the HER2 status. The intrinsic molecular subtype of ER-low positive cases with high FOXC1 and SOX10 mRNA expression was more likely to be nonluminal. Among the ER-low positive/HER2-negative tumors, 56.67% (51 of 90) and 36.67% (33 of 90) were positive for FOXC1 and SOX10, respectively, which was significantly positively correlated with CK5/6 expression. In addition, the survival analysis demonstrated no significant difference between patients who received and who did not receive endocrine therapy.

CONCLUSIONS.—

ER-low positive breast cancers biologically overlap more with ER-negative tumors. ER-low positive/HER2-negative cases demonstrate a high rate of FOXC1 or SOX10 expression, and these cases might be better categorized as a basal-like phenotype/subtype. FOXC1 and SOX10 testing may be used for the intrinsic phenotype prediction for ER-low positive/HER2-negative patients.

Clinical and Biomarker Findings of Neoadjuvant Pembrolizumab and Carboplatin Plus Docetaxel in Triple-Negative Breast Cancer: NeoPACT Phase 2 Clinical Trial

Importance

Addition of pembrolizumab to anthracycline-based chemotherapy improves pathologic complete response (pCR) and event-free survival (EFS) in triple-negative breast cancer (TNBC). The efficacy of anthracycline-free chemoimmunotherapy in TNBC has not been assessed.

Objective

To assess the efficacy of the anthracycline-free neoadjuvant regimen of carboplatin and docetaxel plus pembrolizumab in TNBC.

Design, Setting, and Participants

This was an open-label phase 2 clinical trial including a single group of patients with stage I to III TNBC enrolled at 2 sites who received neoadjuvant carboplatin and docetaxel plus pembrolizumab every 21 days for 6 cycles. Participants were enrolled from 2018 to 2022.

Intervention or Exposure

Carboplatin (with an area under the free carboplatin plasma concentration vs time curve of 6) and docetaxel (75 mg/m2) plus pembrolizumab (200 mg) every 21 days for 6 cycles. Myeloid growth factor support was administered with all cycles.

Main Outcomes and Measures

Primary end point was pathologic complete response (pCR) defined as no evidence of invasive tumor in breast and axilla. The secondary end points were residual cancer burden, EFS, toxicity, and immune biomarkers. RNA isolated from pretreatment tumor tissue was subjected to next-generation sequencing. Specimens were classified as positive or negative for the 44-gene DNA damage immune response (DDIR) signature and for the 27-gene tumor immune microenvironment (TIM; DetermaIO) signature using predefined cutoffs. Stromal tumor-infiltrating lymphocytes (sTILs) were evaluated using standard criteria. Programmed cell death-ligand 1 (PD-L1) testing was performed using a standard immunohistochemical assay.

Results

Among the eligible study population of 115 female patients (median [range] age, 50 [27-70] years) who enrolled from September 2018 to January 2022, 39% had node-positive disease. pCR and residual cancer burden 0 + 1 rates were 58% (95% CI, 48%-67%) and 69% (95% CI, 60%-78%), respectively. Grade 3 or higher immune-mediated adverse events were observed in 3.5% of patients. sTILs, PD-L1, DDIR, and TIM were each predictive of pCR in multivariable analyses. The areas under curve for pCR were 0.719, 0.740, 0.699, and 0.715 for sTILs, PD-L1, DDIR, and TIM, respectively. Estimated 3-year EFS was 86% in all patients; 98% in pCR group and 68% in no-pCR group.

Conclusions and Relevance

The findings of the phase 2 clinical trial indicate that neoadjuvant carboplatin and docetaxel plus pembrolizumab shows encouraging pCR and 3-year EFS. The regimen was well tolerated, and immune enrichment as identified by various biomarkers was independently predictive of pCR. These results provide data on an alternative anthracycline-free chemoimmunotherapy regimen for patients who are not eligible for anthracycline-based regimens and support further evaluation of this regimen as a chemotherapy de-escalation strategy in randomized studies for TNBC.

Trial Registration

ClinicalTrials.gov Identifier: NCT03639948.

Real-world data on neoadjuvant chemotherapy with dual-anti HER2 therapy in HER2 positive breast cancer

BACKGROUND

Neoadjuvant chemotherapy with dual-targeted therapy is the standard treatment for human epidermal growth factor 2 (HER2)-positive breast cancer. Although the dual-targeted therapy has significantly improved the pathological complete response (pCR) rate, further investigation is needed to identify biomarkers that predict the response to neoadjuvant therapy.

METHODS

This retrospective study analyzed 353 patients with HER2-positive breast invasive ductal carcinoma. The correlation between clinicopathological factors and pCR rate was evaluated. A nomogram was constructed based on the results of the multivariate logistic regression analysis to predict the probability of pCR.

RESULTS

The breast pCR (b-pCR) rate was 56.1% (198/353) and the total pCR (t-pCR) rate was 52.7% (186/353). Multivariate analysis identified ER status, PR status, HER2 status, Ki-67 index, and neoadjuvant chemotherapy regimens as independent indicators for both b-pCR and t-pCR. The nomogram had an area under the receiver operating characteristic curve (AUC) of 0.73 (95% CI: 0.68-0.78). According to the nomogram, the t- pCR rate was highest in the ER-PR- HER2-positive patients (131/208) and lowest in the ER + PR + HER2-positive patients (19/73). The subgroup analyses showed that there was no significant difference in pCR rate among the neoadjuvant chemotherapy regimens in ER positive, PR positive, HER2 IHC 2 + , Ki67 index < 30% population. However, for ER-PR-HER2-positive patients, the neoadjuvant chemotherapy regimen has a great influence on the pCR rates.

CONCLUSIONS

Patients with ER-negative, PR-negative, HER2 3 + and high KI-67 index were more likely to achieve pCR. THP may be used as an alternative to AC-THP or TCbHP in selected HER2-positive patients.

The Clinical and Pathological Characteristics That Differentiate Cases With "Low Estrogen Receptor Expression" From Triple-Negative Breast Cancer

Objective

Estrogen receptor (ER) expression is an immunohistochemical marker that is examined in all invasive breast cancers and has prognostic and predictive value. ER-positive breast cancers refer to those that show positivity for ER at 1% cellular expression or higher. The American Society of Clinical Oncology/College of American Pathologists guidelines suggest using the term "low ER-positive breast cancer" for tumors with ER expression between 1% and 10%. Low ER-positive breast cancers exhibit similarities, in terms of disease-free survival and overall survival rates, to triple-negative breast cancers (TNBCs) rather than ER-positive breast cancers. In this study, our aim was to compare the clinicopathological characteristics of low ER-positive breast cancer cases diagnosed and followed in our clinic with TNBCs.

Materials and Methods

A total of 26 cases of low ER-positive breast cancer diagnosed at University of Health Sciences Turkey, İzmir Tepecik Training and Research Hospital between 2010 and 2016 were retrieved from hospital records. The relevant histopathology slides and blocks were retrieved and re-evaluated retrospectively through microscopic examination. Thirteen cases that met the criteria were included in the study. Additionally, a consecutive series of 13 TNBC cases that did not receive neoadjuvant treatment within the same time period were identified.

Results

In the low ER-positive group, the presence of tumor necrosis, as well as histological grade, nuclear grade and Ki-67 proliferation index were significantly lower compared to the TNBC group. Ductal carcinoma in situ (DCIS) was significantly more common in the low ER-positive group compared to the TNBC group. There were no significant differences between the two groups in terms of tumor size, histological tumor type, axillary lymph node involvement, tumor margins, peritumoral and intratumoral inflammation, local recurrence, distant metastasis, survival, and other characteristics.

Conclusion

Although our study consisted of a small number of cases, some features showed significant differences between low ER-positive breast cancers and TNBCs. Histological and nuclear grades, as well as the presence of a DCIS component, were associated with low ER-positive breast cancer. In contrast, the presence of tumor necrosis, as well as Grade 3 features and a high Ki-67 proliferation index indicated TNBC.

Quantitative expression of oestrogen receptor in breast cancer: Clinical and molecular significance

BACKGROUND

Oestrogen receptor (ER) positive breast cancer (BC) patients are eligible for endocrine therapy (ET), regardless of ER immunohistochemical expression level. There is a wide spectrum of ER expression and the response to ET is not uniform. This study aimed to assess the clinical and molecular consequences of ER heterogeneity with respect to ET-response.

METHODS

ER expression, categorised by percentage and staining intensity in a large BC cohort (n = 7559) was correlated with clinicopathological parameters and patient ET response. The Cancer Genome Atlas Data BC cohort (n = 1047) was stratified by ER expression and transcriptomic analysis completed to better understand the molecular basis of ER heterogeneity.

RESULTS

The quantitative proportional increase in ER expression was positively associated with favourable prognostic parameters. Tumours with 1-9% ER expression were characteristically similar to ER-negative (<1%) tumours. Maximum ET-response was observed in tumours with 100% ER expression, with responses significantly different to tumours exhibiting ER at < 100% and significantly decreased survival rates were observed in tumours with 50% and 10% of ER expression. The Histochemical-score (H-score), which considers both staining intensity and percentage, added significant prognostic value over ER percentage alone with significant outcome differences observed at H-scores of 30, 100 and 200. There was a positive correlation between ER expression and ESR1 mRNA expression and expression of ER-regulated genes. Pathway analysis identified differential expression in key cancer-related pathways in different ER-positive groups.

CONCLUSION

ET-response is statistically proportionally related to ER expression with significant differences observed at 10%, 50% and 100%. The H-score adds prognostic and predictive information.

Estrogen-Receptor-Low-Positive Breast Cancer: Pathological and Clinical Perspectives

The expression of estrogen receptors (ERs) in breast cancer (BC) represents a strong prognostic and predictive biomarker and directs therapeutic decisions in early and advanced stages. ER-low-positive BC, defined by the immunohistochemical (IHC) expression of ERs from 1% to 9%, constitutes a distinct subset of total BC cases. Guidelines recommend that a low expression of ERs be reported in pathology reports since the benefit of endocrine therapy in patients with ER-low-positive BC is uncertain. Recently, several cohorts, mostly of a retrospective nature, have been published, reporting the clinicopathological characteristics and outcomes of ER-low-positive BC. However, the majority of the data focus on early-stage BC and the use of (neo)adjuvant therapy, and there is a significant lack of data regarding metastatic ER-low-positive BC. Further factors, including tumor heterogeneity as well as the potential loss of ER expression due to endocrine resistance, should be considered. Including patients with ER-low-positive BC in clinical trials for triple-negative breast cancer (TNBC) might improve the understanding of this entity and allow novel therapeutic approaches. The design and conduction of randomized clinical trials regarding this subgroup of patients are greatly anticipated.

Fasting-mimicking diet: a metabolic approach for the treatment of breast cancer

PURPOSE OF REVIEW

Metabolic reprogramming is a new and potentially targetable hallmark of cancer. In recent years, fasting and fasting-mimicking diets (FMDs) have been tested as anticancer strategies both in preclinical experiments and in clinical trials. In this review, we aim at summarizing the available evidence about the antitumour activity of these approaches in preclinical breast cancer models, as well as results from clinical trials investigating fasting/FMD in breast cancer patients.

RECENT FINDINGS

Preclinical evidence demonstrated that nutrient deprivation boosts the antitumor activity of chemotherapy, immunotherapy or targeted therapies in triple-negative breast cancer (TNBC) and HR+/HER2 models through both cell-autonomous antitumour effects in cancer cells and favourable modifications in intratumor immune cells. Several clinical experiences demonstrated that fasting/FMD is feasible and well tolerated in combination with standard treatments in BC patients, and that it could reduce chemotherapy-related toxicities. Finally, despite the absence of randomized trials demonstrating the antitumor activity of fasting/FMD in breast cancer patients, preliminary clinical reports suggest that this experimental nutritional strategy may enhance chemotherapy activity. Randomized clinical trials are ongoing to validate these results at a larger scale.

SUMMARY

Fasting/FMD is a promising therapeutic approach in patients with breast cancer; ongoing and future trials will confirm their role in improving breast cancer care.

Reassessing Estrogen Receptor Expression Thresholds for Breast Cancer Prognosis in HER2-negative Patients Using Shape Restricted Modeling

Purpose

To assess the dynamic link between continuous estrogen receptor (ER) expression and long-term clinical outcomes in non-metastatic breast cancer and to identify the ideal cutoff value for ER expression to optimize endocrine therapy use.

Methods

The study included 3055 female patients with stage II or III HER2-negative breast cancer. The primary outcomes were time to recurrence or death (TTR) and overall survival (OS). We used a novel shape-restricted Cox model to determine the desirable ER expression cutoff to predict breast cancer prognoses. Our novel model allows ER as a continuous variable, utilizing a flexible monotone-shaped Cox regression to assess its association with survival outcomes holistically.

Results

The shape-restricted Cox model identified 10% ER as the preferred cutoff to predict TTR. The finding was confirmed by the log-rank test and standard Cox model that patients with ER ≥ 10% had TTR benefit over ER < 10% (log-rank p < 0.001). No OS or TTR benefit of adjuvant endocrine therapy was observed in patients with 1% ≤ ER < 10% (HR 0.877, 95% CI 0.481-1.600, p = 0.668 for TTR and HR 0.698, 95% CI 0.337-1.446, p = 0.333 for OS).

Conclusions

Using the shape-restricted Cox model, this study suggests a potential preferred threshold of 10% for predicting TTR. The findings could assist physicians in effectively weighing the benefits and risks of adjuvant endocrine therapy for patients with ER < 10% disease, particularly in cases involving severe adverse events. Further prospective studies are warranted to validate the recommended cutoff value.

Neoadjuvant Immunotherapy in Early, Triple-Negative Breast Cancers: Catching Up with the Rest

Despite breast cancer being long thought to be "immunologically cold," within early, triple-negative breast cancer (TNBC), there has been exciting advances with the use of immune checkpoint modulation combined with neoadjuvant chemotherapy. We review the major trials that have investigated combination immunochemotherapy in the neoadjuvant setting, reviewing both the pathological complete response rates and the maturing data regarding event-free and overall survival. Strategies to deescalate adjuvant therapy in patients with preserving excellent clinical outcome, as well as exploration of combinatorial adjuvant therapies to improve outcome in those with extensive residual are the next-generation challenges. In addition to refinement of existing biomarkers, such as PD-L1, TILs, and tumor mutational burden (TMB), exploration of topics like the microbiome as both a biomarker and a therapeutic has shown promise in other cancer types, which motivates investigating these in breast cancer.

The Clinical and Biological Significance of Estrogen Receptor-Low Positive Breast Cancer

Estrogen receptor (ER) status in breast cancer (BC) is determined using immunohistochemistry (IHC) with nuclear expression in ≥1% of cells defined as ER-positive. BC with 1%-9% expression (ER-low-positive), is a clinically and biologically unique subgroup. In this study, we hypothesized that ER-low-positive BC represents a heterogeneous group with a mixture of ER-positive and ER-negative tumor, which may explain their divergent clinical behavior. A large BC cohort (n = 8171) was investigated and categorized into 3 groups: ER-low-positive (1%-9%), ER-positive (≥10%), and ER-negative (<1%) where clinicopathological and outcome characteristics were compared. A subset of ER-low-positive cases was further evaluated using IHC, RNAscope, and RT-qPCR. PAM50 subtyping and ESR1 mRNA expression levels were assessed in ER-low-positive cases within The Cancer Genome Atlas data set. The reliability of image analysis software in assessment of ER expression in the ER-low-positive category was also assessed. ER-low-positive tumors constituted <2% of BC cases examined and showed significant clinicopathological similarity to ER-negative tumors. Most of these tumors were nonluminal types showing low ESR1 mRNA expression. Further validation of ER status revealed that 45% of these tumors were ER-negative with repeated IHC staining and confirmed by RNAscope and RT-qPCR. ER-low-positive tumors diagnosed on needle core biopsy were enriched with false-positive ER staining. BCs with 10% ER behaved similar to ER-positive, rather than ER-negative or low-positive BCs. Moderate concordance was found in assessment of ER-low-positive tumors, and this was not improved by image analysis. Routinely diagnosed ER-low-positive BC includes a proportion of ER-negative cases. We recommend repeat testing of BC showing 1%-9% ER expression and using a cutoff ≥10% expression to define ER positivity to help better inform treatment decisions.

Arbeitsgemeinschaft Gynäkologische Onkologie Recommendations for the Diagnosis and Treatment of Patients with Early Breast Cancer: Update 2023

Background

Each year the interdisciplinary Arbeitsgemeinschaft Gynäkologische Onkologie (AGO), German Gynecological Oncology Group Breast Committee on Diagnosis and Treatment of Breast Cancer provides updated state-of-the-art recommendations for early and metastatic breast cancer.

Summary

The updated evidence-based treatment recommendation for early and metastatic breast cancer has been released in March 2023.

Key Messages

This paper concisely captures the updated recommendations for early breast cancer chapter by chapter.

Immune landscape of breast tumors with low and intermediate estrogen receptor expression

Immune checkpoint blockade (ICB) is currently approved for patients with triple-negative breast cancer (TNBC), whereas responses to ICB are also observed in a small subgroup of Estrogen Receptor (ER)-positive breast cancer. The cut-off for ER-positivity (≥1%) is based on likelihood of endocrine treatment response, but ER-positive breast cancer represents a very heterogeneous group. This raises the question whether selection based on ER-negativity should be revisited to select patients for ICB treatment in the context of clinical trials. Stromal tumor-infiltrating lymphocytes (sTILs) and other immune parameters are higher in TNBC compared to ER-positive breast cancer, but it is unknown whether lower ER levels are associated with more inflamed tumor microenvironments (TME). We collected a consecutive series of primary tumors from 173 HER2-negative breast cancer patients, enriched for tumors with ER expression between 1 and 99% and found levels of stromal TILs, CD8 + T cells, and PD-L1 positivity in breast tumors with ER 1-9% and ER 10-50% to be comparable to tumors with ER 0%. Expression of immune-related gene signatures in tumors with ER 1-9% and ER 10-50% was comparable to ER 0%, and higher than in tumors with ER 51-99% and ER 100%. Our results suggest that the immune landscape of ER low tumors (1-9%) and ER intermediate tumors (10-50%) mimic that of primary TNBC.

Defining triple-negative breast cancer with neuroendocrine differentiation (TNBC-NED)

Primary breast neuroendocrine (NE) neoplasms are uncommon, and definitions harbor controversy. We retrospectively collected 73 triple-negative breast cancers (TNBC) and evaluated NE biomarker expression along with p53 aberrant staining (which correlates with TP53 gene mutation) and Rb protein loss by immunohistochemistry. In the study cohort, we found 11 (15%) cases of TNBC with neuroendocrine differentiation (TNBC-NED) showing positivity for one or more NE markers (synaptophysin/chromogranin/insulinoma-associated protein 1 [INSM1]). We also identified one separate small cell neuroendocrine carcinoma. Histologic types for these 11 TNBC-NED cases were as follows: 8 invasive ductal carcinoma (IDC) not otherwise specified (NOS), 2 IDC with apocrine features, 1 IDC with solid papillary features. INSM1 had the highest positivity and was seen in all 11 carcinomas. Seven (64%) cases showed p53 aberrant staining, 6 (55%) had Rb protein loss, while 6 (55%) had p53/Rb co-aberrant staining/protein loss. TNBC-NED was associated with Rb protein loss (p < 0.001), as well as p53/Rb co-aberrant staining/protein loss (p < 0.001). In 61 cases negative for NE markers, 37 (61%) showed p53 aberrant staining, while 5 (8%) had Rb protein loss. We also analyzed genomic and transcriptomic data from The Cancer Genome Atlas (TCGA) PanCancer Atlas of 171 basal/TNBC patients. Transcriptomic analysis revealed mRNA expression of RB1 to be correlated negatively with SYN1 mRNA expression (p = 0.0400) and INSM1 mRNA expression (p = 0.0106) in this cohort. We would like to highlight the importance of these findings. TNBC-NED is currently diagnosed as TNBC, and although it overlaps morphologically with TNBC without NED, the unique p53/Rb signature highlights a genetic overlap with NE carcinomas of the breast.

Concordance of immunohistochemistry for predictive and prognostic factors in breast cancer between biopsy and surgical excision: a single-centre experience and review of the literature

PURPOSE

Accurate evaluation of breast cancer on bioptic samples is of fundamental importance to guide therapeutic decisions, especially in the neoadjuvant or metastatic setting. We aimed to assess concordance for oestrogen receptor (ER), progesterone receptor (PR), c-erbB2/HER2 and Ki-67. We also reviewed the current literature to evaluate our results in the context of the data available at present.

METHODS

We included patients who underwent both biopsy and surgical resection for breast cancer at San Matteo Hospital, Pavia, Italy, between January 2014 and December 2020. ER, PR, c-erbB2, and Ki-67 immunohistochemistry concordance between biopsy and surgical specimen was evaluated. ER was further analysed to include the recently defined ER-low-positive in our analysis.

RESULTS

We evaluated 923 patients. Concordance between biopsy and surgical specimen for ER, ER-low-positive, PR, c-erbB2 and Ki-67 was, respectively, 97.83, 47.8, 94.26, 68 and 86.13%. Cohen's κ for interobserver agreement was very good for ER and good for PR, c-erbB2 and Ki-67. Concordance was especially low (37%) in the c-erbB2 1 + category.

CONCLUSION

Oestrogen and progesterone receptor status can be safely assessed on preoperative samples. The results of this study advise caution in interpreting biopsy results regarding ER-low-positive, c-erbB2/HER and Ki-67 results due to a still suboptimal concordance. The low concordance for c-erbB2 1 + cases underlines the importance of further training in this area, in the light of the future therapeutic perspectives.

Exploring immune interactions in triple negative breast cancer: IL-1β inhibition and its therapeutic potential

Triple negative breast cancer (TNBC) has poor prognosis when compared to other breast cancer subtypes. Despite pre-clinical data supporting an immune targeted approach for TNBCs, immunotherapy has failed to demonstrate the impressive responses seen in other solid tumor malignancies. Additional strategies to modify the tumor immune microenvironment and potentiate response to immunotherapy are needed. In this review, we summarise phase III data supporting the use of immunotherapy for TNBC. We discuss the role of IL-1β in tumorigenesis and summarize pre-clinical data supporting IL-1β inhibition as a potential therapeutic strategy in TNBC. Finally, we present current trials evaluating IL-1β in breast cancer and other solid tumor malignancies and discuss future studies that may provide a strong scientific rationale for the combination of IL-1β and immunotherapy in the neoadjuvant and metastatic setting for people with TNBC.

Aldehyde dehydrogenase 2 polymorphism is associated with chemotherapy-related cognitive impairment in patients with breast cancer who receive chemotherapy

BACKGROUND

Chemotherapy-related cognitive impairment (CRCI) is a common but easily overlooked condition that markedly affects the quality of life (QOL) of patients with breast cancer. The rs671 is a common gene polymorphism of aldehyde dehydrogenase 2 (ALDH2) in Asia that is involved in aldehyde metabolism and may be closely related to CRCI. However, no study has yet summarised the association between ALDH2 and CRCI.

METHODS

This study enrolled one hundred and twenty-four patients diagnosed with breast cancer according to the pathology results, genotyped for ALDH2 single-nucleotide polymorphisms (SNP) to explore these. The mini-mental state exam (MMSE), verbal fluency test (VFT), and digit span test (DST) results were compared in these patients before and after chemotherapy (CT).

RESULTS

We found that patients with ALDH2 gene genotypes of rs671_GG, rs886205_GG, rs4648328_CC, and rs4767944_TT polymorphisms were more likely to suffer from cognitive impairment during chemotherapy. A trend toward statistical significance was observed for rs671_GG of DST (z = 2.769, p = 0.006), VFT (t = 4.624, P<0.001); rs886205_GG of DST (z = 3.663, P<0.001); rs4648328_CC of DST (z = 2.850, p = 0.004), VFT (t = 3.477, p = 0.001); and rs4767944_TT of DST (z = 2.967, p = 0.003), VFT (t = 2.776, p = 0.008). The cognitive indicators of these patients significantly decreased after chemotherapy (p < 0.05). The difference in ALDH2 rs671 was most obvious.

CONCLUSION

Our results showed what kinds of ALDH2 genotyped patients that are more likely to develop CRCI. In the future, it may be possible to infer the risk of CRCI by detecting the single-nucleotide locus of ALDH2 that is conducive to strengthening clinical interventions for these patients and improving their QOL. More importantly, this study has important implications for Asian women with breast cancer as ALDH2 rs671 is a common polymorphism in Asians.

Optimizing choices and sequences in the diagnostic-therapeutic landscape of advanced triple-negative breast cancer: An Italian consensus paper and critical review

Triple-negative (TN) metastatic breast cancer (mBC) represents the most challenging scenario withing mBC framework, and it has been only slightly affected by the tremendous advancements in terms of drug availability and survival prolongation we have witnessed in the last years for advanced disease. However, although chemotherapy still represents the mainstay of TN mBC management, in the past years, several novel effective agents have been developed and made available in the clinical practice setting. Within this framework, a panel composed of a scientific board of 17 internationally recognized breast oncologists and 42 oncologists working within local spoke centers, addressed 26 high-priority statements, including grey areas, regarding the management of TN mBC. A structured methodology based on a modified Delphi approach to administer the survey and the Nominal Group Technique to capture perceptions and preferences on the management of TN mBC within the Italian Oncology community were adopted. The Panel produced a set of prioritized considerations/consensus statements reflecting the Panel position on diagnostic and staging approach, first-line and second-line treatments of PD-L1-positive/germline BRCA (gBRCA) wild-type, PD-L1-positive/gBRCA mutated, PD-L1-negative/gBRCA wild-type and PD-L1-negative/gBRCA mutated TN mBC. The Panel critically and comprehensively discussed the most relevant and/or unexpected results and put forward possible interpretations for statements not reaching the consensus threshold.

[Triple-negative breast cancer : Classification, current concepts, and therapy-related factors]

Triple-negative breast cancer (TNBC) accounts for about 10% of all breast cancer cases and is defined by the lack of expression of estrogen and progesterone receptors and the lack of overexpression or amplification of HER2. It differs with regard to the younger age of the patients, an increased association with a mutation of BRCA1 and a mostly low differentiation from hormone receptor-positive breast cancer. The spectrum of triple-negative breast cancer shows considerable heterogeneity both at the morphological and at the molecular level. It includes most commonly TNBC of no special type, with and without basal phenotype, triple-negative metaplastic breast carcinomas, triple-negative breast carcinomas with apocrine differentiation and rare triple-negative tumor types. At the gene-expression level, TNBC most commonly is associated with a basal phenotype, with rarer molecular variants of TNBC involving the Claudin-low, molecular apocrine types, and other rarer subtypes. Therefore, a critical use of the term TNBC, considering the histopathological tumor differentiation, is recommended.

Incorporating weekly carboplatin in anthracycline and paclitaxel-containing neoadjuvant chemotherapy for triple-negative breast cancer: propensity-score matching analysis and TIL evaluation

BACKGROUND

The generation of data capturing the risk-benefit ratio of incorporating carboplatin (Cb) to neoadjuvant chemotherapy (NACT) for triple-negative breast cancer (TNBC) in a clinical practice setting is urgently needed. Tumour-infiltrating lymphocytes (TILs) have an established role in TNBC receiving NACT, however, the role of TIL dynamics under NACT exposure in patients receiving the current standard of care is largely uncharted.

METHODS

Consecutive TNBC patients receiving anthracycline-taxane [A-T] +/- Cb NACT at three Institutions were enrolled. Stromal-TILs were evaluated on pre-NACT and residual disease (RD) specimens. In the clinical cohort, propensity-score-matching was used to control selection bias.

RESULTS

In total, 247 patients were included (A-T = 40.5%, A-TCb = 59.5%). After propensity-score-matching, pCR was significantly higher for A-TCb vs A-T (51.9% vs 34.2%, multivariate: OR = 2.40, P = 0.01). No differences in grade ≥3 haematological toxicities were observed. TILs increased from baseline to RD in the overall population and across A-T/A-TCb subgroups. TIL increase from baseline to RD was positively and independently associated with distant disease-free survival (multivariate: HR = 0.43, P = 0.05).

CONCLUSIONS

We confirmed in a clinical practice setting of TNBC patients receiving A-T NACT that the incorporation of weekly Cb significantly improved pCR. In addition, A-T +/- Cb enhanced immune infiltration from baseline to RD. Finally, we reported a positive independent prognostic role of TIL increase after NACT exposure.

Marker assessments in ER-positive breast cancers: old markers, new applications?

Evaluation of oestrogen receptor (ER) expression by immunostaining is essential in the pathological assessment of breast cancer. Its expression is intercorrelated with clinicopathological features, molecular typing, and treatment selection. The development of novel therapeutic agents related to ER status, the recent ASCO introduction of an ER-low positive category of breast cancers, and the ever-increasing plethora of diagnostic and theragnostic markers call for a timely update. In this article we aim to review the clinicopathological features of ER-positive breast cancers, with an emphasis on ER-low positive breast cancers, and a focus on updating the (i) assessment, reporting and interpretation of ER immunohistochemical (IHC) staining, (ii) correlations of ER status with other diagnostic and theragnostic markers, and (iii) implications for treatment selection and response. In the face of the developments in IHC and molecular techniques and targeted therapy, ER immunostaining is still expected to remain as the core component of prognostic and theragnostic assessment of breast cancers.

Systemic therapy for early-stage breast cancer: learning from the past to build the future

The treatment of breast cancer has improved dramatically over the past century, from a strictly surgical approach to a coordinated one, including local and systemic therapies. Systemic therapies for early-stage disease were initially tested against observation or placebo only in adjuvant trials. Subsequent clinical trials focusing on treatment 'fine-tuning' had a marked increase in cohort size, duration and costs, leading to a growing interest in the neoadjuvant setting in the past decade. Neoadjuvant trial designs have the advantages of enabling the direct evaluation of treatment effects on tumour diameter and offer unique translational research opportunities through the comparative analysis of tumour biology before, during and after treatment. Current technologies enabling the identification of better predictive biomarkers are shaping the new era of (neo)adjuvant trials. An urgent need exists to reinforce collaboration between the pharmaceutical industry and academia to share data and thus establish large databases of biomarker data coupled with patient outcomes that are easily accessible to the scientific community. In this Review, we summarize the evolution of (neo)adjuvant trials from the pre-genomic to the post-genomic era and provide critical insights into how neoadjuvant studies are currently designed, discussing the need for better end points and treatment strategies that are more personalized, including in the post-neoadjuvant setting.

Clinical implication of low estrogen receptor (ER-low) expression in breast cancer

Breast cancer is a heterogeneous disease, and the estrogen receptor (ER) remains the most important biomarker in breast oncology. Most guidelines set a positive expression threshold of 1% staining in immunohistochemistry (IHC) to define ER positivity. However, different expression levels may be associated with diverse degrees of sensitivity to endocrine therapy as ER expression may impact breast cancer molecular biology as a continuous variable. ER-lo tumors, defined as those with 1-10% ER expression, represent a relatively small subgroup of breast cancer patients, with an estimated prevalence of 2-7%. These tumors are similar to ERneg disease in their molecular landscape, clinicopathological characteristics, prognosis, and response to therapy. Nevertheless, a proportion may retain some degree of ER signaling dependency, and the possibility of responding to some degree to endocrine therapy cannot be completely ruled out. This review article discusses the most important considerations regarding the definition of ER positivity, pathology assessment, prognosis, and therapeutic implication of ERlo breast cancer from the medical oncology perspective.

Intrinsic subtypes and therapeutic decision-making in hormone receptor-positive/HER2-negative metastatic breast cancer with visceral crisis: A case report

Background

CDK4/6 inhibitors (CDKi), namely, palbociclib, ribociclib, and abemaciclib, combined with either an aromatase inhibitor (AI) or fulvestrant are the standard first/second line for hormone receptor-positive(HR+)/HER2-negative(neg) metastatic breast cancer (MBC). However, the choice of one specific CDKi is arbitrary and based on the physician's experience with the drug, toxicity profile, and patient's preferences, whereas biomarkers for optimal patient selection have not been established so far. Moreover, upfront chemotherapy is still recommended in case of clinical presentation with visceral crisis, despite no evidence of superior benefit for chemotherapy regimens against CDKi-based regimens. Recent correlative biomarker analyses from pivotal trials of palbociclib and ribociclib showed that HR+/HER2-neg MBC might respond differently according to the molecular intrinsic subtype, with Luminal A and B tumors being sensitive to both CDKi, Basal-like being insensitive to endocrine therapy, irrespective of CDKi, and HER2-enriched tumors showing a benefit only with ribociclib-based therapy.

Clinical case

We hereby present a paradigmatic clinical case of a woman affected by a relapsed HR+/HER2-neg MBC with bone and nodal lesions, presenting with a visceral crisis in the form of lymphangitis carcinomatosis and diagnosed with a molecularly HER2-enriched tumor, successfully treated with upfront ribociclib + fulvestrant. The patient experienced a complete symptomatic and radiologic remission of the lymphangitis with a partial response as best response, according to RECIST 1.1 criteria. The progression-free survival (PFS) was of 20 months, in line with the median PFS observed in the ribociclib + fulvestrant pivotal trial, where, however, patients with visceral crisis had been excluded.

Conclusions

This clinical case confirms in the real-world setting that non-luminal subtypes can be found in HR+/HER2-neg disease and may have potential therapeutic implications in the metastatic setting. It also questions the recommendation of upfront chemotherapy in the case of a visceral crisis in the era of CDKi-based regimens. These issues merit further evaluation in prospective and larger studies.

Contribution of endocrine therapy in oestrogen receptor-positive pT1a-b breast cancer: Results of a retrospective study

INTRODUCTION

Few data have been reported regarding endocrine therapy (ET) in patients with small pT1a-b ER-postive breast cancer (BC). Thus, we conducted a study to detect possible survival improvements due to ET in such patients.

METHODS

Our retrospective observational study included 5545 patients with pT1a-b ER-positive BC treated in 15 French centres, excluding patients with HER2-positive status, neoadjuvant chemotherapy, ER-negative status, unknown pN status or in situ BC. We estimated disease-free survival (DFS), recurrence-free survival (RFS) and overall survival (OS) via univariate analysis and multivariate Cox regression.

RESULTS

Most patients (80.3%: 4453) received ET and-when compared to those without ET-experienced increases of 2.5% and 3.3% in DFS and 1.9% and 4.3% in RFS after 5 and 7 years of follow-up, respectively, with little difference in OS. In Cox regression analysis, no ET was significantly associated with decreased DFS (hazard ratio, HR = 1.275, p = 0.047, 95% CI[1.003-1.620]) but not OS or RFS in all patients, while in 2363 patients with pT1a-b ER-positive grade 2-3 BC, no ET was significantly associated with decreased DFS (HR = 1.502, p = 0.049, 95% CI[1.001-2.252]), but not OS (HR = 1.361, p = 0.272). ET omission was not significantly associated with decreased survival in 3047 patients with pT1a-b ER-positive grade 1 BC.

CONCLUSION

Our results indicate that while ET provided a beneficial impact on survival to patients with pT1a-bN0 ER-positive BC-and especially in those with grade 2-3 tumours-no such impact was observed in grade 1 tumours. Consequently, ET should be discussed with these patients, particularly in those with pT1a grade 1 tumours.

Optimal Choice of Neoadjuvant Chemotherapy for HER2-Negative Breast Cancer: Clinical Insights

The neoadjuvant setting provides immense opportunities for translational research and drug development. The acceptance of pathological complete response (pCR) as a surrogate endpoint for clinical benefit has led to the widespread use of neoadjuvant treatment. Optimal neoadjuvant therapies are determined based on their ability to achieve the highest rates of pCR. Predicted rates of pCR for triple negative breast cancer (TNBC) treated with sequential taxane/anthracycline regimens range from 35% to 48%. With the addition of a platinum agent pCR rates of 55% are predicted. Further increases have been observed with the addition of immune checkpoint inhibitors to this standard chemotherapy backbone. In the pivotal KEYNOTE-522 clinical trial pCR rates of 65% and 69% were reported for chemotherapy plus pembrolizumab in the overall and PD-L1-positive subgroup respectively. The role of the neoadjuvant chemotherapy is less clear in hormone receptor (HR)-positive, human epidermal growth factor receptor-2 (HER2)-negative breast cancer. In general, HR–positive cancers have the least chance of achieving a pCR after neoadjuvant chemotherapy, especially if they are low-grade. If neoadjuvant chemotherapy is given for high-risk HR-positive, HER2-negative breast cancer, standard adjuvant anthracycline/taxane regimens are appropriate. Optimum endocrine therapy is the standard-of-care in the adjuvant setting regardless of pCR. There are several genomic signatures available to guide decisions regarding adjuvant chemotherapy use however these assays are not routinely used in the neoadjuvant setting. For high-risk patients meeting the criteria for the monarchE trial adjuvant abemaciclib in addition to endocrine therapy is associated with an improvement in disease free survival (DFS) at 3 years. Based on the OlympiA trial patients with germline BRCA mutations should be considered for adjuvant olaparib therapy. In this article we review neoadjuvant clinical trials that guide optimum treatment options for TNBC and HR-positive, HER2-negative breast cancer.

Impact of low versus negative estrogen/progesterone receptor status on clinico-pathologic characteristics and survival outcomes in HER2-negative breast cancer

Triple-negative breast cancer (TNBC) is classically defined by estrogen receptor (ER) and progesterone receptor (PR) immunohistochemistry expression <1% and absence of HER2 amplification/overexpression. HER2-negative breast cancer with low ER/PR expression (1–10%) has a gene expression profile similar to TNBC; however, real-world treatment patterns, chemotherapy response, endocrine therapy benefit, and survival outcomes for the Low-ER group are not well known. 516 patients with stage I-III HER2-negative breast cancer and ER/PR expression ≤10% who were enrolled in a multisite prospective registry between 2011 and 2019 were categorized on the basis of ER/PR expression. TNBC (ER and PR < 1%) and Low-ER (ER and/or PR 1–10%) groups comprised 87.4% (n = 451) and 12.6% (n = 65) of patients, respectively. Demographic, clinical, and treatment characteristics, including prevalence of germline BRCA1/2 mutation, racial and ethnic distribution, and chemotherapy use were not different between TNBC and Low-ER groups. No difference was observed in recurrence-free survival (RFS) and overall survival (OS) between TNBC and Low-ER groups (3-year RFS 82.5% versus 82.4%, respectively, p = 0.728; 3-year OS 88.0% versus 83.4%, respectively, p = 0.632). Among 358 patients receiving neoadjuvant chemotherapy, rates of pathologic complete response were similar for TNBC and Low-ER groups (49.2% vs 51.3%, respectively, p = 0.808). The HER2-negative Low-ER group is often excluded from TNBC clinical trials assessing novel treatments (immunotherapy and antibody-drug conjugates), thus limiting efficacy data for newer effective therapies in this group. Given that HER2-negative Low-ER disease displays clinical characteristics and outcomes similar to TNBC, inclusion of this group in TNBC clinical trials is encouraged.

Immunotherapy for triple negative breast cancer: How can pathologic responses to experimental drugs in early-stage disease be enhanced?

INTRODUCTION

: The treatment landscape of early triple negative breast cancer (TNBC) has recently expanded after the Food and Drug Administration (FDA) approval of pembrolizumab in combination with neoadjuvant chemotherapy. The addition of this immune checkpoint inhibitor (ICI) has shown to significantly increased pathological complete response (pCR) rate and event free survival (EFS) in the KEYNOTE-522 phase 3 trial. Several additional studies are ongoing with the goal of further improving outcomes and achieving an optimal integration of ICIs in the treatment of TNBC.

AREAS COVERED

: The article examines pCR and survival rates in TNBC. It appraises clinical trials investigating neoadjuvant ICIs for TNBC and the improvement of pCR rates (biomarker-driven escalation of treatment, optimization of chemotherapy backbone and addition of locoregional treatments or innovative agents). Insights on the role of pCR as surrogate endpoint and the possibility of enhancing pCR rates for women affected by early TNBC are offered.

EXPERT OPINION

: The pharmacopoeia of early TNBC is growing and becoming more heterogeneous with the advent of ICIs; to enhance the clinical benefit of patients, it is necessary to develop response endpoints that consider the mechanism of action of experimental drugs, to optimize patient selection through validated biomarkers, and to compare the most promising treatment strategies in randomized clinical trials.

HER2-low-positive breast cancer: evolution from primary tumor to residual disease after neoadjuvant treatment

Approximately a half of breast tumors classified as HER2-negative exhibit HER2-low-positive expression. We recently described a high instability of HER2-low-positive expression from primary breast cancer (BC) to relapse. Previous studies reporting discordance in HER2 status between baseline biopsy and residual disease (RD) in patients undergoing neoadjuvant treatment did not include the HER2-low-positive category. The aim of this study is to track the evolution of HER2-low-positive expression from primary BC to RD after neoadjuvant treatment. Patients undergoing neoadjuvant treatment with available baseline tumor tissue and matched samples of RD (in case of no pCR) were included. HER2-negative cases were sub-classified as HER2-0 or HER2-low-positive (IHC 1+ or 2+ and ISH negative). Four-hundred forty-six patients were included. Primary BC phenotype was: HR-positive/HER2-negative 23.5%, triple-negative (TN) 35%, HER2-positive 41.5%. HER2-low-positive cases were 55.6% of the HER2-negative cohort and were significantly enriched in the HR-positive/HER2-negative vs. TN subgroup (68.6% vs. 46.8%, p = 0.001 χ2 test). In all, 35.3% of non-pCR patients (n = 291) had a HER2-low-positive expression on RD. The overall rate of HER2 expression discordance was 26.4%, mostly driven by HER2-negative cases converting either from (14.8%) or to (8.9%) HER2-low-positive phenotype. Among HR-positive/HER2-negative patients with HER2-low-positive expression on RD, 32.0% and 57.1% had an estimated high risk of relapse according to the residual proliferative cancer burden and CPS-EG score, respectively. In conclusion, HER2-low-positive expression showed high instability from primary BC to RD after neoadjuvant treatment. HER2-low-positive expression on RD may guide personalized adjuvant treatment for high-risk patients in the context of clinical trials with novel anti-HER2 antibody-drug conjugates.

Effector memory cytotoxic CD3+/CD8+/CD45RO+ T cells are predictive of good survival and a lower risk of recurrence in triple-negative breast cancer

Triple-negative breast cancer (TNBC) with high tumour-infiltrating lymphocytes (TILs) has been associated with a promising prognosis. To better understand the prognostic value of immune cell subtypes in TNBC, we characterised TILs and the interaction between tumour cells and immune cell subtypes. A total of 145 breast cancer tissues were stained by multiplex immunofluorescence (mIF), including panel 1 (PD-L1, PD-1, CD3, CD8, CD68 and CK) and panel 2 (Foxp3, Granzyme B, CD45RO, CD3, CD8 and CK). Phenotypes were analysed and quantified by pathologists using InForm software. We found that in the ER-negative (ER <1% and HER2-negative) group and the ER/PR-low positive (ER 1-9% and HER2-negative) group, 11.2% and 7.1% of patients were PD-L1⁺ by the tumour cell score, 29.0% and 28.6% were PD-L1⁺ by the modified immune cell score and 30.8% and 32.1% were PD-L1⁺ by the combined positive score. We combined ER-negative and ER/PR-low positive cases for the survival analysis since a 10% cut-off is often used in clinical practice for therapeutic purposes. The densities of PD-L1⁺ tumour cells (HR: 0.366, 95% CI: 0.138-0.970; p = 0.043) within the tumour compartment and CD3⁺ immune cells in the total area (tumour and stromal compartments combined) (HR: 0.213, 95% CI: 0.070-0.642; p = 0.006) were favourable prognostic biomarkers for overall survival (OS) in TNBC. The density of effector/memory cytotoxic T cells (CD3⁺CD8⁺CD45RO⁺) in the tumour compartment was an independent prognostic biomarker for OS (HR: 0.232, 95% CI: 0.086-0.628; p = 0.004) and DFS (HR: 0.183, 95% CI: 0.1301-0.744; p = 0.009) in TNBC. Interestingly, spatial data suggested that patients with a higher density of PD-L1⁺ tumour cells had shorter cell-cell distances from tumour cells to cytotoxic T cells (p < 0.01). In conclusion, we found that phenotyping tumour immune cells by mIF is highly informative in understanding the immune microenvironment in TNBC. PD-L1⁺ tumour cells, total T cells and effector/memory cytotoxic T cells are promising prognostic biomarkers in TNBC.

Prognostic Relevance of Progesterone Receptor Levels in Early Luminal-Like HER2 Negative Breast Cancer Subtypes: A Retrospective Analysis

Introduction

In luminal-like early breast cancer (BC), the lack of Progesterone Receptor (PR) expression generally correlates with more aggressive behavior but the clinical validity of low PR levels remains a debated issue.

Methods

The main aim of this retrospective analysis was to assess the survival outcome (Breast cancer specific survival, BCSS) in a cohort of 687 luminal-like HER2 negative early BC patients treated at our Institutions from January 2000 to December 2018, using a sub-classification of tumors in subgroup 1 (PR high/Ki67 low), subgroup 2 (PR high/Ki67 high), subgroup 3 (PR low/Ki67 low), subgroup 4 (PR low/Ki67 high) according to PR and Ki67 values.

Results

At a median follow-up of 7 years, BCSS rates were 96.3%, 89%, 86.8% and 85% in the subgroup 1, 2, 3, 4 respectively. Overall, a statistically significant difference in BCSS rates was observed among the 4 subgroups (p=0.0036). On univariate analysis, post-menopause, older age (≥ 50 years), low PR and high Ki67 expression, poorly differentiated grade and size ≥ 2 cm as well as luminal B-like tumors (subgroups 2, 3, 4) were significantly associated with a worse BCSS. Multivariate analysis identified grade, size and subgroup classification of BC as independent prognostic markers of poorer outcome. In particular, subgroups 4, 3 and 2 displayed a significantly higher risk of BC-related death (HR=4.11; p=0.008; HR=3.43; p=0-007; HR=2.57; p=0.020, respectively) when compared to subgroup 1.

Conclusions

Our results support the usefulness of PR and Ki67 levels as prognostic markers, corroborating their crucial role in the decision-making process of patients with luminal-like HER2 negative early BC. Clinical application of these parameters should be assessed prospectively.