HER2-enriched Subtype Research Articles

Role of Intrinsic Subtype Analysis with PAM50 in Hormone Receptors Positive HER2 Negative Metastatic Breast Cancer: A Systematic Review.

Endocrine therapy (ET), associated with CDK 4/6 inhibitors, represents the first choice of treatment for HR+/HER2- metastatic breast cancer (mBC). Primary or secondary endocrine resistance could develop; however validated biomarkers capable of predicting such a conditions are not available. Several studies have shown that HR+/HER2- mBC comprises five intrinsic subtypes. The purpose of this systematic review was to analyze the potential correlations between intrinsic subtype, efficacy of treatment, and patient outcome. Five papers that analyzed the intrinsic subtype with PAM50 assay in patients (pts) with HR+/HER2- mBC treated with ET (alone or in combination) within seven phase III clinical trials (EGF30008, BOLERO-2, PALOMA-2,3, MONALEESA-2,3,7) were identified. Non-luminal subtypes are more frequent in endocrine-resistant pts and in metastatic sites (vs. primary tumors), have less benefit from ET, and worse prognosis. Among these, HER2-enriched subtypes are similar to HER2+ tumors and benefit from the addition of anti-HER2 agents (lapatinib) and, for less clear reasons, of ribociclib (unconfirmed data for palbociclib and everolimus). Basal-like subtypes are similar to triple-negative tumors, making them more sensitive to chemotherapy. The intrinsic subtype is also not static but can vary over time with the evolution of the disease. Currently, the intrinsic subtype does not play a decisive role in the choice of treatment in clinical practice, but has potential prognostic and predictive value that should be further investigated.

Intra- and Peritumoral Radiomics Model Based on Early DCE-MRI for Preoperative Prediction of Molecular Subtypes in Invasive Ductal Breast Carcinoma: A Multitask Machine Learning Study.

PurposeThe aim of this study is to investigate radiomics features extracted from the optimal peritumoral region and the intratumoral area on the early phase of dynamic contrast-enhanced MRI (DCE-MRI) for predicting molecular subtypes of invasive ductal breast carcinoma (IDBC).MethodsA total of 422 IDBC patients with immunohistochemical and fluorescence in situ hybridization results from two hospitals (Center 1: 327 cases, Center 2: 95 cases) who underwent preoperative DCE-MRI were retrospectively enrolled. After image preprocessing, radiomic features were extracted from the intratumoral area and four peritumoral regions on DCE-MRI from two centers, and selected the optimal peritumoral region. Based on the intratumoral, peritumoral radiomics features, and clinical–radiological characteristics, five radiomics models were constructed through support vector machine (SVM) in multiple classification tasks related to molecular subtypes and visualized by nomogram. The performance of radiomics models was evaluated by receiver operating characteristic curves, confusion matrix, calibration curves, and decision curve analysis.ResultsA 6-mm peritumoral size was defined the optimal peritumoral region in classification tasks of hormone receptor (HR)-positive vs others, triple-negative breast cancer (TNBC) vs others, and HR-positive vs human epidermal growth factor receptor 2 (HER2)-enriched vs TNBC, and 8 mm was applied in HER2-enriched vs others. The combined clinical–radiological and radiomics models in three binary classification tasks (HR-positive vs others, HER2-enriched vs others, TNBC vs others) obtained optimal performance with AUCs of 0.838, 0.848, and 0.930 in the training cohort, respectively; 0.827, 0.813, and 0.879 in the internal test cohort, respectively; and 0.791, 0.707, and 0.852 in the external test cohort, respectively.ConclusionRadiomics features in the intratumoral and peritumoral regions of IDBC on DCE-MRI had a potential to predict the HR-positive, HER2-enriched, and TNBC molecular subtypes preoperatively.

Abstract 464: AI-powered segmentation and analysis of nuclei morphology predicts genomic and clinical markers in multiple cancer types

Abstract Morphological features of cancer cell nuclei are linked to gene expression signatures and genomic alterations. In addition, pathologists have leveraged nuclear morphology as diagnostic and prognostic markers. To enable the use of nuclear morphology in digital pathology, we developed a pan-tissue, deep-learning-based digital pathology pipeline for exhaustive nucleus detection, instance segmentation, and classification. We collected > 29,000 manual nucleus annotations from hematoxylin and eosin (H&E)-stained pathology images from 21 tumor types at 40x and 20x magnification from The Cancer Genome Atlas (TCGA) project, as well as a proprietary set of H&E-stained tissue biopsies of skin, liver non-alcoholic steatohepatitis (NASH), colon inflammatory bowel disease (IBD), and kidney lupus. Annotations were used to train an object detection and segmentation model for identifying nuclei. Application of the model to held-out test data, including held-out tissue types, demonstrated performance comparable to state-of-the-art models described in the literature (mean Dice score = 0.80, aggregated Jaccard index = 0.60). We deployed our model to segment nuclei in H&E slides from the breast cancer (BRCA, N = 941) and prostate adenocarcinoma (PRAD, N = 457) TCGA cohorts. We extracted interpretable features describing the shape (circularity, eccentricity), size, staining intensity (mean and standard deviation), and texture of each nucleus. Nuclei were assigned as cancer or other cell types using separately trained convolutional neural networks for BRCA and PRAD. We used the mean and standard deviation of each feature sampled from a random subset of cancer nuclei to summarize the nuclear morphology on each slide (mean (range) = 10,068 (5,981-10,452) cancer cells from each BRCA slide; mean (range) = 10,053 (5,029-10,495) cancer cells from each PRAD slide). We used nuclear features to construct random forest classification models for predicting markers of genomic instability and prognosis: whole-genome doubling (WGD) and homologous recombination deficiency (HRD) status separately in BRCA and PRAD, HER2 subtype in BRCA, and Gleason grade in PRAD. Nuclear features were predictive of WGD (area under the receiver operating characteristic curve (AUROC) = 0.78 BRCA, = 0.69 PRAD) and binarized HRD status (AUROC = 0.65 BRCA, = 0.68 PRAD) on held-out test sets. Nuclear features were predictive of HER2-enriched breast cancer vs. other molecular subtypes (AUROC = 0.72), and distinguished between low risk (6) and moderate/high risk (7-10) Gleason grade in PRAD (AUROC = 0.72). In summary, we present a powerful pan-tissue approach for nucleus segmentation and featurization, which enables the construction of predictive models and the identification of features linking nuclear morphology with clinically-relevant prognostic biomarkers across multiple cancer types. Citation Format: John Abel, Suyog Jain, Deepta Rajan, Ken Leidal, Harshith Padigela, Aaditya Prakash, Jake Conway, Michael Nercessian, Christian Kirkup, Robert Egger, Ben Trotter, Andrew Beck, Ilan Wapinski, Michael G. Drage, Limin Yu, Amaro Taylor-Weiner. AI-powered segmentation and analysis of nuclei morphology predicts genomic and clinical markers in multiple cancer types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 464.

Combined analysis of receptor expression reflects inter-and intra-tumor heterogeneity in HR+/HER2+ breast cancer.

Hormone receptor-positive and human epidermal growth factor receptor 2-positive (HR+/HER2+ breast cancer comprise approximately 5-10% of all invasive breast cancers. However, the lack of knowledge regarding the complexity of tumor heterogeneity in HR+/HER2+ disease remains a barrier to more accurate therapies. This study aimed to describe the tumor heterogeneity of HR+/HER2+ breast cancer and to establish a novel indicator to identify the HER2-enriched subtype in patients with HR+/HER2+ breast cancer. First of all, a comprehensive analysis was performed on HR+/HER2+ breast cancer samples from the TCGA (n = 141) and METABRIC (n = 104) databases. We determined the distribution of PAM50 intrinsic subtypes within the two cohorts and compared the somatic mutational profile and RNA expression features between HER2-enriched and non-HER2-enriched subtypes. From this, we constructed a novel marker termed rH/E, which was calculated as ERBB2 expression quantity/(ESR1 expression quantity + 1). Secondly, we performed multiplex immunofluorescence (mIF) to evaluate HER2 and estrogen receptor (ER) expression simultaneously in the third cohort, enrolling 43 cases of early HR+/HER2+ breast cancer from Cancer Hospital, Chinese Academy of Medical Sciences (CAMS). When using mIF, rH/E was adjusted to prH/E, which was calculated as HER2-positive cells%/(ER-positive cells + 1)%. All four main intrinsic subtypes were identified in HR+/HER2+ breast cancer, of which the luminal B subtype was the most common, followed by the HER2-enriched and luminal A subtypes. Significantly increased TP53 and ERBB3 and decreased PIK3CA somatic mutation frequency were observed in the HER2-enriched subtype compared with the non-HER2-enriched subtype. In addition, the HER2-enriched subtype was characterized by significantly higher ERBB2 and lower ESR1 expression. We then constructed a marker termed rH/E to reflect the relative expression of ERBB2 to ESR1 in each patient. rH/E discriminates the HER2-enriched subtype from the better than the expression of ERBB2 or ESR1 alone. In the CAMS cohort, we observed four subtypes of tumor cells: ER+/HER2-, ER+/HER2+, ER-/HER2+, and ER-/HER2-. Tumor cell diversity was common, with 86% of patients having all four subtypes of tumor cells. Moreover, prH/E showed a significant prognostic association in the CAMS cohort. This study furthers our understanding of the complexity of tumor heterogeneity in HR+/HER2+ breast cancer, and suggests that the combined analysis of ERBB2 and ESR1 expression may contribute to identifying patients with specific subtypes in this population.

Breast cancer in young women in Guatemala: A retrospective comparative cohort study.

e13523 Background: In Guatemala, breast cancer is the most common malignancy among women, the socioeconomic variability among the population directly affects the access to screening and treatment, and little is known about the behavior of the disease among younger women, reason why the aim of our study is to describe the clinico-pathological characteristics in this population. Methods: Retrospective study performed of patients with a confirmed biopsy of breast cancer that were treated at Liga Nacional Contra el Cáncer - INCAN in Guatemala, the largest cancer center in the country. From medical records, we obtained: clinico-pathological and treatment (surgery, radiotherapy, endocrine therapy) data and compared results between ≤40 years and >40 years old women. Results: The study identified 1,347 patients, 190 (16.42%) ≤40 years old women and 1,157 (83.57%) >40 years old. The mean age at diagnosis among patients was 36 vs. 56 years old, respectively (p<0.01). According to our findings, even though most patients came from the region I of the country that is the capital city, there was a higher percentage of patients from the West regions (VI, VII) that belonged to the younger group 22.22% vs 10.58%. Furthermore, 74.4% of ≤40 years old patients were staged as locally advanced or metastatic vs >40 year old patients (48.04%), and 65.34% of ≤40 years old were found to have triple negative and Her2 enriched subtypes vs 46.13% in >40 years old (p<0.01). Conclusions: Young breast cancer patients in Guatemala are characterized by being diagnosed at locally advanced and advanced stages of the disease with more biologically aggressive subtypes such as triple negative and her2 enriched. [Table: see text]

The decline of circulating tumor cell clusters count for predicting the treatment response in breast cancer patients.

e13009 Background: Circulating tumor cells (CTCs) are the precursors of metastatic cancer because they originate from primary tumor sites into the vascular system. The prognostic information of CTCs was well established in breast cancer treatment while the predictive value was still unclear. The aim of this study was to analyze the predictive value of CTCs count during treatment. Materials and Methods: A prospective study was conducted from 2019 to 2021, and 31 female breast cancer patients were enrolled, and 54 blood samples were collected at Linkou Chang Gung Memorial Hospital. The median age was 47 years old. We used LIPO platform for CTC isolation with anti-EpCAM antibody. To achieve maximum cellular viability, the LIPO platform was further optimized by using liposomes-lipid bilayers instead of lipid bilayers as the underneath surface coating to facilitate the detachment of bound cells from the surface and maintain cellular viability. Results: Fourteen patients were Stage II or stage III (non-metastasis) and 17 metastatic patients were included. Eleven patients (35.5%) were ER-positive HER2-negative while 10 patients (32.6%) were ER-positive HER2-positive. Three patients (9.7%) were HER2 enriched subtypes, and 7 patients (22.6%) were triple negative breast cancer. Blood samples from a total of 28 patients can be analyzed. At least one CTC was detected in 44/49 (89.8%) blood samples, CTC can’t be identified in 2/5 (40%) post-treatment with good response. The average single CTC count per 2 ml was 34.40 in non-metastatic patients versus 110.43 in metastatic patients (p = 0.3895). The average clustered CTC count per 2 ml was 13.44 in non-metastatic patients versus 40.16 in metastatic patients (p = 0.424). The total single and clustered CTC count per 2 ml was 47.84 non-metastatic patients versus 150.59 in metastatic patients (p = 0.3977). In 10 patients with clinically partial response, the average single CTC count per 2 ml was 61.9 before treatment and 11.81 after treatment (p = 0.0716), and the average clustered CTC per 2 ml was 15.83 before treatment and 5.28 after treatment (p = 0.8806). In 4 patients with clinical progression, the average single CTC count per 2 ml was 22.694 before treatment and 26.125 after treatment (p = 0.0257), and the average clustered CTC per 2 ml was 7.69 before treatment and 16.61 after treatment (p = 0.3798). Conclusions: Our findings concluded that the decline of circulating tumor cell clusters count can predict the treatment response in breast cancer patients.

Prognostic and predictive implications of the intrinsic subtypes and gene expression signatures in early-stage HER2+ breast cancer: A pooled analysis of CALGB 40601, NeoALTTO, and NSABP B-41 trials.

509 Background: Several biologic features are implicated in the differences in response and survival to dual (trastuzumab and lapatinib [HL]) vs. single (trastuzumab [H]) HER2-blockade across neoadjuvant trials in early-stage HER2+ breast cancer. We evaluated the association of intrinsic subtypes and gene expression signatures with pathologic complete response (pCR) and event-free survival (EFS) in a pooled analysis of three independent phase III neoadjuvant studies with similar designs: CALGB 40601 (Alliance), NeoALTTO, and NSABP B-41. Methods: Gene expression profiling by RNA sequencing was assessed on 761 pre-treatment samples (264 from CALGB 40601, 249 from NeoALTTO, 248 from NSABP B-41). Intrinsic subtypes and 759 gene expression signatures were calculated. We studied the association of pCR and the benefit of dual (HL) vs. single (H) HER2-blockade by tumor intrinsic subtype in the pooled set. The ability of multiple gene expression signatures to predict pCR and EFS across the three studies was also tested by logistic and Cox regression analyses. Results: pCR status was associated with EFS only in HER2-Enriched (HR 0.45, 95% CI 0.29-0.71, p-value < 0.001) and Basal-like (HR 0.19, 95% CI 0.04-0.86, p-value 0.031) intrinsic subtypes, but not in Luminal and/or ER+ tumors. The EFS benefit of dual vs. single HER2-blockade was limited to HER2-Enriched tumors (HR 0.47, 95% CI 0.27-0.81, p-value 0.007). When evaluating the three clinical trials separately, we found 89/759 (11.7%) gene expression signatures in common for the prediction of pCR across the three clinical trials, including HER2-amplicon and immune activation signatures. Luminal-related signatures were associated with lower pCR rates but better EFS outcomes, especially in patients with residual disease. Stratified Cox regression models by study showed a significant and strong association of NK, B and plasma cells, as well as Ig-related signatures with a better EFS outcome, while vascular, proliferation, and metastasis signatures were associated with poor EFS. Conclusions: In early-stage HER2+ breast cancer, the relationship between pCR and EFS differs by tumor intrinsic subtype, and the benefit of dual vs. single HER2-blockade seems to be limited to HER2-Enriched subtype tumors. Immune signatures were associated with higher pCR rates and better EFS, luminal signatures were associated with lower pCR rates but good EFS outcomes, and vascular/proliferation/metastasis signatures were associated with poor EFS across the three clinical trials. Clinical trial identification: CALGB 40601: NCT00770809. (CALGB is part of the Alliance for Clinical Trials in Oncology). NeoALTTO: NCT00553358 NSABP B-41: NCT00486668

Lactate dehydrogenase as a surrogate marker for both PCR and survival in breast cancer patients who underwent neoadjuvant chemotherapy.

e12621 Background: Glucose metabolism in cancer cells produces various glycolytic metabolites, which can affect cancer progression and treatment outcome. Herein we evaluated the association of glucose transporters and enzymes involved in glucose metabolism with clinic-pathological factors and outcomes in breast cancer patients who underwent neoadjuvant chemotherapy(NAC). Methods: We selected 7 target transporters and enzymes(GLUT1, hexokinase 2, lactate dehydrogenase, MCT1, MCT4, IGF1RA, and IGF1RB) involved in glucose metabolism. Their tumoral expressions were scored both quantitively and qualitatively based on tissue microarrays and immunohistochemistry as previously described (Pinheiro et al, 2010) and then evaluated in relationships with pretreatment clinical/pathological characteristics and treatment outcomes including findings of 18F-FDG PET/CT,pathologic complete response(pCR), and relapse in breast cancer(stage IIA-IIIC) patients who underwent anthracycline or taxane-based NAC. Results: Of the 236 enrolled patients, 145(61.4%), 44(18.6%), and 47(19.9%) were luminal, HER2-enriched, and TNBC subtypes. Pathologic CR was determined 50(21.2%) and 57(24.2%) relapses, 42(17.8%) distant relapses, and 28 deaths were observed during median follow-up duration of 64.0 (32.3-114.9) months. The expression rates of the target molecules were 76.0, 31.1, 42.1, 54.9, 67.9, 78.4, and 49.8% for GLUT1, hexokinase 2 (HK2), lactate dehydrogenase(LD), MCT1, MCT4, IGF1RA, and IGF1RB, respectively. Among target molecules in glucose metabolism, LD was significantly associated with pCR(OR = 0.251; p- = 0.016) and distant disease-free survival (HR = 2.29; P = 0.019). Plus, LD expression shows a trend for a high SUVmax of primary tumor 18F-FDG PET/CT(OR = 1.797 P = 0.060). Conclusions: Tumoral expression of lactate dehydrogenase can be considered as a predictive marker for pCR to NAC and plus prognostic marker for survival in patients with breast cancer.

Depiction of breast cancers on digital mammograms by artificial intelligence-based computer-assisted diagnosis according to cancer characteristics.

To evaluate how breast cancers are depicted by artificial intelligence-based computer-assisted diagnosis (AI-CAD) according to clinical, radiological, and pathological factors. From January 2017 to December 2017, 896 patients diagnosed with 930 breast cancers were enrolled in this retrospective study. Commercial AI-CAD was applied to digital mammograms and abnormality scores were obtained. We evaluated the abnormality score according to clinical, radiological, and pathological characteristics. False-negative results were defined by abnormality scores less than 10. The median abnormality score of 930 breasts was 87.4 (range 0-99). The false-negative rate of AI-CAD was 19.4% (180/930). Cancers with an abnormality score of more than 90 showed a high proportion of palpable lesions, BI-RADS 4c and 5 lesions, cancers presenting as mass with or without microcalcifications and invasive cancers compared with low-scored cancers (all p < 0.001). False-negative cancers were more likely to develop in asymptomatic patients and extremely dense breasts and to be diagnosed as occult breast cancers and DCIS compared to detected cancers. Breast cancers depicted with high abnormality scores by AI-CAD are associated with higher BI-RADS category, invasive pathology, and higher cancer stage. • High-scored cancers by AI-CAD included a high proportion of BI-RADS 4c and 5 lesions, masses with or without microcalcifications, and cancers with invasive pathology. • Among invasive cancers, cancers with higher T and N stage and HER2-enriched subtype were depicted with higher abnormality scores by AI-CAD. • Cancers missed by AI-CAD tended to be in asymptomatic patients and extremely dense breasts and to be diagnosed as occult breast cancers by radiologists.

CORRELATION OF RECEPTOR STATUS WITH AXILLARY NODAL METASTASIS AND OTHER PROGNOSTIC FACTORS IN CARCINOMA BREAST : INDIAN PERSPECTIVE

Background- nd Breast cancer is the 2 most common cancer globally and it ranks rst in India. The predictive value of various components like hormone receptor status, tumor size, grade to axillary lymph nodal metastasis has been studied previously. Our aim is to study the correlation of receptor status and axillary lymph nodal metastasis in breast cancer patients. Methods- This is a retrospective study carried out in single surgical unit. 104 biopsy proven unilateral breast cancer patients who underwent modied radical mastectomy has been reviewed. The clinicopathological data has been collected from hospital records. Results- The mean age of presentation is 42.2years. Most common age group is 30-49years with clinical stage III(65.38%) with inltrating ductal carcinoma(99.03%). Although axillary lymph node was palpable in 75%, nodal metastasis is present in 63.46% of patients. Positive estrogen receptor, progesterone receptor and Her2 receptors are seen in 45.19%, 34.6% and 59.61% patients respectively. TNBC patients has least while triple positive has maximum nodal metastasis in our study group. Perineural invasion and extra capsular extension is seen in 15.38% each and lymphovascular invasion is seen in 38.4% patient. Although LVI, PNI and ECE is predominant in Her2-enriched subtypes, most patients belonging to HR+/Her2+ subtypes has LVI, PNI and ECE. TNBC and HR+/Her2- subtypes has least LVI, PNI and ECE. Conclusion- Receptor status has signicant role in predicting nodal metastasis. TNBC, although considered most aggressive, has least axillary nodal metastasis suggesting less lymphatic involvement and less LVI, PNI and ECE. Also Her2 over-expression seems to be related to nodal metastasis, LVI, PNI and ECE, suggesting there may be some pathway which is still unrevealed. Thus Her2 receptor positivity can be considered as an independent poor prognostic factor.

Application of next-generation sequencing in detection of BRCA1/2 and homologous recombination repair pathway multi-genes germline mutation and correlation analysis

Objective: To investigate the germline mutation status of related genes in breast cancer patients and high-risk individuals by next-generation sequencing. To analyze the correlations between homologous recombination repair (HR) pathway gene mutation status and clinicopathological characteristics of breast cancer patients. To supplement the database of breast cancer related gene mutations in Chinese population. Methods: This study is a cross-sectional study. From October 2020 to September 2021, whole blood samples were collected from 350 breast cancer patients and 49 high-risk individuals, admitted to Peking University People's Hospital and accepted genetic testing voluntarily. Germline mutations in 32 breast cancer related genes were detected by NGS. The clinicopathological characteristics, including age at the onset, family history, unilateral/bilateral tumor, Luminal typing (Luminal A subtype, Luminal B subtype, HER2-enriched subtype and triple negative breast cancer), tumor size and metastasis, were analyzed, and the correlations between HR pathway gene mutation status and clinicopathological characteristics were analyzed by Chi-squared test and Fisher's exact probability test. Results: Among 350 breast cancer patients, 64 (18.3%) cases carried gene pathogenic mutations (including pathogenic and likely pathogenic mutations), including 47 (13.4%) in BRCA1/2, 16 (4.6%) in non-BRCA1/2 genes, 1 (0.3%) in BRCA2 and FANCL. Among 49 high-risk individuals, 7 (14.3%) cases carried gene pathogenic mutations, including 6 (12.3%) in BRCA1/2 and 1 (2%) in ATM genes. BRCA1/2 pathogenic mutations were associated with age at the onset (18%, 8.7%, χ²=6.346, P=0.012), and the BRCA1/2 pathogenic mutation frequency was higher in patients diagnosed at age ≤45 years. HR pathway gene mutations (including pathogenic, likely pathogenic and uncertain significance mutations) were correlated with unilateral/bilateral tumor (49.5%, 68.4%, χ²=4.841, P=0.028) and Luminal typing (45.7%, 62.2%, 32%, 60%, χ²=12.004, P=0.007), and the HR mutation frequencies were higher in patients with bilateral tumor, Luminal B breast cancer and triple negative breast cancer (TNBC). Conclusion: The BRCA1/2 pathogenic mutation frequency in high-risk individuals is similar to that in breast cancer patients, and BRCA1/2 testing is helpful to guide breast cancer screening and prevention in high-risk individuals. Patients with early onset breast cancer, bilateral breast cancer, Luminal B breast cancer and TNBC have higher mutation frequencies of HR pathway genes, and HR pathway genes testing should be conducted as soon as possible to provide laboratory evidence for diagnosis, treatment, prognosis and risk evaluation of breast cancer.

HER2-Low Breast Cancer: Prognosis and Future Treatment Prospective

The human epidermal growth factor 2 (HER2) is a tyrosine kinase belonging to the Human Epidermal Receptor family [1]. HER2 is amplified leading to HER2 overexpression in 15% of breast cancers (BC) [2]. HER2 overexpression leads to poor prognosis, but offers the unique possibility to use a targeted therapy with monoclonal antibodies. This therapeutic option has radically changed the history of HER2 BC [3]. HER2 overexpression represents at present the most powerful predictive factor for likeliness of response to anti-HER2 agents [5]. The HER2 status is routinely assessed either using immunohistochemistry (HER2 protein expression level) or in situ hybridization (HER2 gene status) [2,5,6]. For the purpose of HER2 assessment, international guidelines have been developed by experts in the field, and have changed over the years according to new data. HER2 heterogeneity is linked to the complexity of equivocal results, HER2 mutations and the upcoming category of HER2-low BC [7]. Intratumor genetic heterogeneity interests various types of human cancers, including BC and HER2 overexpression and amplification, and it is demonstrated to be significantly more common in cases with HER2 equivocal status [8]. Equivocal cases frequently feature low levels of HER2 amplification. Several studies showed that HER2 heterogeneity is related to poor outcome, shorter disease-free survival and overall survival. Patients with HER2 heterogeneity are less responsive to target therapies as confirmed by a lower achievement of pathologic complete response following neoadjuvant treatment [9]. In spite of the scarcity of data still available on HER2-low BC, different intrinsic subtypes seem to influence different clinical behavior and response to treatment, as this has already been proved for other BC subtypes. HER2-low/HR- BC showed a higher frequency of HER2-enriched instrinsic subtype than HER2-/HR- BC. This might mean that, despite in clinical practice HER2-low/HR- BC is considered as HER2-/HR, these subtypes of BCs might reflect a different clinical behavior and a different response to targeted therapy [10]. Recent studies underlined that HER2-enriched instrinsic subtype are the most beneficial in reduction of risk of progression and death after CDK6/6-inhibitors treatment, compared to the other subtypes [11]. Traditionally HER2-positive BCs were separated from HER2-negative BCs, based on solid clinical data stating that only tumors driven by HER2 oncogene addition benefit from targeted therapies [12]. However in recent years new therapies have been developed, in particular the antibody drug conjugates which deliver chemotherapy inside the BC. Some of these agents - such as trastuzumab duocarmazine and trastuzumab deruxtecan showed encouraging response rates also in the so called HER2-low BC. For example, the phase 1 study of DS-8201 showed an overall response rate of 37% in pretreated HER2-low metastatic cancer patients, with a median duration of response of 10.4 months [13]. These data suggests a paradigm shift in the definition of HER2 status, which may be based on 3 groups: 1.HER2-positive, 2.HER2- negative, 3.HER2-low BCs, that may potentially benefit from a targeted therapy, even in absence of the addition of the tumor cells to the HER2 oncogene [7]. At present there are no formal definitions of HER2-low BC, but it seems reasonable to define as HER2-low all BCs displaying a score of 1+ or 2+ HER2 expression and no HER2 amplification. This assumption would categorize up to 55% of BCs as HER2-low. For this subtype there are no targeted therapies approved [7]. The majority of HER2 somatic mutations found in BCs have not been associated with HER2 gene amplification. However preclinical data suggest that functionally active HER2 mutations may lead to HER2 targeted therapies sensitivity [14]. Other preclinical models suggest that pertuzumab inhibits tumor proliferation even in absence of HER2 overexpression [15].So, HER2 mutation-positive but HER2-negative BC may benefit from targeted drugs, but further studies are needed. For example, trastuzumab, deruxtecan, a novel enzyme-cleavable linker, showed significant objective response and disease control in a group of patients including 25% HER2-low BCs, and therefore is worthy of further studies in this subgroup of patients [16]. The new agents being tested for HER2-low BC patients are antibody drug conjugates deploying anti-HER2 epitopes in their antibody component, but with different cytotoxic warheads and a bi-specific antibody targeting both HER2 and HER3 [17]. In conclusion, the concept of HER2-positive versus HER2-negative disease is changing, including the definition of “HER2-low” BC, against which new therapies such as antibody drug conjugates may be extremely effective.

Association of Fruit, Vegetable, and Animal Food Intakes with Breast Cancer Risk Overall and by Molecular Subtype among Vietnamese Women.

Evidence on associations between dietary intake and risk of breast cancer subtypes is limited and inconsistent. We evaluated associations of fruit, vegetable, meat, and fish consumption with risk of breast cancer overall and by molecular subtype in the Vietnamese Breast Cancer Study (VBCS). VBCS includes 476 incident breast cancer cases and 454 age-matched controls. Dietary habits over the past 5 years were assessed by in-person interviews using a validated food frequency questionnaire. Associations of food groups with breast cancer were evaluated via logistic regression for overall and molecular subtype with adjustment for age, education, income, family history of cancer, menopausal status, body mass index, exercise, total energy intake, and other potential dietary confounders. Odds ratio (OR) was used to approximate relative risk. High fruit intake was inversely associated with breast cancer risk, with adjusted ORs [95% confidence intervals (CI)] of 0.67 (95% CI, 0.47-0.95) and 0.41 (95% CI, 0.27-0.61) for second and third tertiles versus first tertile, respectively (Ptrend < 0.001). This association was stronger for triple-negative than other subtypes (Pheterogeneity < 0.001). High intake of freshwater fish was inversely associated with overall breast cancer (ORT3vsT1 = 0.63; 95% CI, 0.42-0.95; Ptrend = 0.03). An inverse association was observed between HER2-enriched subtype and red and organ meat intake (ORT3vsT1 = 0.40; 95% CI, 0.17-0.93; Ptrend = 0.04; Pheterogeneity = 0.50). High intakes of fruit and freshwater fish were associated with reduced breast cancer risk; association for the former was stronger for triple-negative subtype. Our findings suggest high intakes of fruit and freshwater fish may reduce breast cancer risk among Vietnamese women.

MiR-101-5p Acts as a Tumor Suppressor in HER2-Positive Breast Cancer Cells and Improves Targeted Therapy.

PurposeHuman epidermal growth factor receptor 2 positive (HER2+) breast cancers responding poorly to targeted therapy need improved treatment options. miR-101-5p has shown tumor-suppressive properties in multiple cancer forms, and we assessed the effect and mechanism of action of this miRNA in HER2+ breast cancer.MethodsExpression levels of miR-101-5p in two clinical datasets, TCGA and METABRIC, were compared between tumor and normal adjacent samples, and across molecular subtypes and HER2 status. The ability of miR-101-5p to sensitize for treatment with lapatinib, tucatinib and trastuzumab was explored in HER2+ breast cancer cells responding poorly to such targeted drugs. Proliferation and apoptosis assays and downstream protein analysis were performed.ResultsExpression levels of miR-101-5p were significantly lower in tumor compared to normal adjacent tissue (p < 0.001), and particularly low in HER2+ tumors, both the HER2-enriched subtype (p ≤ 0.037) and clinical HER2-status (p < 0.001). In a HER2+ cell line (KPL4) responding poorly to targeted drugs, miR-101-5p overexpression inhibited proliferation (p < 0.001), and combinatorial treatment with lapatinib and trastuzumab significantly further decreased this inhibition (p = 0.004). Proteomic data and in silico analyses revealed PI3K/Akt- and HER2-pathways among the predicted regulated pathways. miR-101-5p alone (p = 0.018) and in combination with lapatinib and trastuzumab (p < 0.001) induced apoptosis, while the targeted drugs alone did not exert any significant effect neither on proliferation nor apoptosis.ConclusionmiR-101-5p acts as a tumor suppressor by inducing apoptosis in HER2+ breast cancer and sensitizes cells with initially poor response to lapatinib and trastuzumab.

Effects of Ruxolitinib and Calcitriol Combination Treatment on Various Molecular Subtypes of Breast Cancer.

The anticancer effects of ruxolitinib and calcitriol against breast cancer were reported previously. However, the effect of ruxolitinib and calcitriol combination treatment on various molecular subtypes of breast cancer remains unexplored. In this study, we used MCF-7, SKBR3, and MDA-MB-468 cells to investigate the effect of ruxolitinib and calcitriol combination treatment on cell proliferation, apoptosis, cell cycle, and cell signaling markers, in vitro and in vivo. Our results revealed the synergistic anticancer effect of ruxolitinib and calcitriol combination treatment in SKBR3 and MDA-MB-468 cells, but not in MCF-7 cells in vitro, via cell proliferation inhibition, apoptosis induction, cell cycle arrest, and the alteration of cell signaling protein expression, including cell cycle-related (cyclin D1, CDK1, CDK4, p21, and p27), apoptosis-related (c-caspase and c-PARP), and cell proliferation-related (c-Myc, p-p53, and p-JAK2) proteins. Furthermore, in the MDA-MB-468 xenograft mouse model, we demonstrated the synergistic antitumor effect of ruxolitinib and calcitriol combination treatment, including the alteration of c-PARP, cyclin D1, and c-Myc expression, without significant drug toxicity. The combination exhibited a synergistic effect in HER2-enriched and triple-negative breast cancer subtypes. In conclusion, our results suggest different effects of the combination treatment of ruxolitinib and calcitriol depending on the molecular subtype of breast cancer.

Abstract PD10-11: Keyriched-1- A prospective, multicenter, open label, neoadjuvant phase ii single arm study with pembrolizumab in combination with dual anti-HER2 blockade with trastuzumab and pertuzumab in early breast cancer patients with molecular HER2-enriched intrinsic subtype

Abstract Background: De-escalating strategies seem promising in HER2-positive early breast cancer (EBC) and chemo-free regimens are thus of key interest. Recent data have underlined the role of tumor immunogenicity in response to de-escalated neoadjuvant anti-HER2 therapy. Therefore, the prospective single arm hypothesis-generating phase II KEYRICHED-1 trial (NCT03988036) investigates the pCR-rate in patients with HER2-enriched EBC receiving four cycles of the dual anti-HER2 blockade in combination with the checkpoint inhibitor pembrolizumab. Initial studies with dual antibody-based HER2 blockade alone were able to achieve pCR-rates of 20-40%, which did not quite match the pCR-rates obtained with concurrent chemotherapy. KEYRICHED-1 aims at achieving pCR-rates comparable to standard chemotherapy-containing regimens by incorporating appropriate molecular selection and immune oncology.. Methods: A total of 48 pre- and postmenopausal patients with newly diagnosed HER2 2+ or 3+ EBC (stage I-III) and HER2-enriched (HER2-E) subtype by PAM50 were enrolled in this single-arm study. All patients received four cycles of study treatment with pembrolizumab (200mg), trastuzumab biosimilar (Trazimera®, loading dose 8mg/kg bodyweight (BW), maintenance dose 6mg/kg BW), and pertuzumab (loading dose 840mg/kg BW, maintenance dose 420mg/kg BW) q21d. Primary endpoint was centrally confirmed pCR (ypT0/is, ypN0). The trial was planned as a Simon's two-stage design (null and alternative pCR were 40% and 60%); interim analysis after 16 patients had to show a pCR rate of at least 50% to continue recruitment.. Results: Between 05/2020 and 03/2021, 98 patients were screened. N=52 (55%) had HER2-E subtype, of whom 48 patients entered the treatment phase. Median patient age was 57 years (28-83). 65% had tumors &amp;gt; 2 cm and 30% positive lymph node status. Centrally confirmed pCR-rate in surgical specimens was 46% (95% CI 0.31-0.62) in the 43 patients of the per-protocol-population, and 52% (95%CI 0.37-0.67) in all 46 evaluable patients (local assessment; two pCRs verified only by core biopsy) (p=0.22 and p=0.06 for null hypothesis, respectively). Despite HER2-E subtype, no pCR was observed in the four patients with immunohistochemical (IHC) HER2 2+/ISH-positive status in contrast to 20/39 (51.2%) pCR in IHC HER2 3+ tumors. Centrally confirmed pCR-rate in HR+/HER2+ tumors was 38.5% compared to 58.5% in HR-/HER2+ tumors. No new safety signals were observed.. Conclusions: These are the first results of a neoadjuvant chemotherapy-free 12-week de-escalation anti-HER2-regimen with trastuzumab and pertuzumab in combination with the PD-1 inhibitor pembrolizumab in patients with a HER2-E EBC. In the context of the WSG ADAPT HER2+ de-escalation trials the observed pCR-rates compare favorably in HR+ as well as HR- HER2+ EBC. Moreover, KEYRICHED-1 demonstrates that with appropriate molecular patient selection clinically meaningful pCR-rates in the range of those obtained with longer, more toxic chemotherapy-containing regimens can be achieved. Citation Format: Sherko Kuemmel, Oleg Gluz, Mattea Reinisch, Athina Kostara, Iris Scheffen, Monika Graeser, Rachel Wuerstlein, Ulrike Nitz, Kerstin Luedtke-Heckenkamp, Andreas Hartkopf, Felix Hilpert, Angela Kentsch, Carsten Ziske, Reinhard Depenbusch, Michael Braun, Jens Blohmer, Christine zu Eulenburg, Matthias Christgen, Stephan Bartels, Hans Kreipe, Enrico Pelz, Peter Schmid, Nadia Harbeck. Keyriched-1- A prospective, multicenter, open label, neoadjuvant phase ii single arm study with pembrolizumab in combination with dual anti-HER2 blockade with trastuzumab and pertuzumab in early breast cancer patients with molecular HER2-enriched intrinsic subtype [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 PD10-11.

Abstract P2-13-03: KEYRICHED-1 - A prospective, multicenter, open label, neoadjuvant phase II single arm study with pembrolizumab in combination with dual anti-HER2 blockade with trastuzumab and pertuzumab in early breast cancer patients with molecular HER2-enriched intrinsic subtype

Abstract Background: De-escalating strategies seem promising inHER2-positive early breast cancer (EBC) and chemo-free regimens are thus of keyinterest. Recent data have underlined the role of tumor immunogenicity inresponse to de-escalated neoadjuvant anti-HER2 therapy. Therefore, theprospective single arm hypothesis-generating phase II KEYRICHED-1 trial (NCT03988036)investigates the pCR rate in patients with HER2-enriched EBC receiving fourcycles of the dual anti-HER2 blockade in combination with the checkpointinhibitor pembrolizumab. Initial studies with dual antibody-based HER2 blockadealone were able to achieve pCR-rates of 20-40%, which did not quite match the pCRrates obtained with concurrent chemotherapy. KEYRICHED-1 aims at achieving pCR-ratescomparable to standard chemotherapy-containing regimens by incorporating appropriatemolecular selection and immune oncology. Methods: A total of 48 pre- and postmenopausal patients with newly diagnosed HER22+ or 3+ EBC (stage I-III) and HER2-enriched (HER2-E) subtype by PAM50 wereenrolled in this single-arm study. All patients received four cycles of studytreatment with pembrolizumab (200mg), trastuzumab biosimilar (Trazimera®,loading dose 8mg/kg bodyweight (BW), maintenance dose 6mg/kg BW), and pertuzumab(loading dose 840mg/kg BW, maintenance dose 420mg/kg BW) q21d . Primaryendpoint was centrally confirmed pCR (ypT0/is, ypN0). The trial was planned asa Simon's two-Stage design (null and alternative pCR were 40% and 60%); interimanalysis after 16 patients had to show a pCR rate of at least 50% to continuerecruitment. Results: Between 05/2020 and 03/2021, 98 patients werescreened. N=52 (55%) had HER2-E subtype,of whom 48 patients entered thetreatment phase. Median patient age was 57 years (28-83). 65% had tumors &amp;gt; 2cm and 30% positive lymph node status. Centrally confirmed pCR rate in surgicalspecimens was 46% (95% CI 0.31-0.62) in the 43 patients of the per protocolpopulation, and 52% (95%CI 0.37-0.67) in all 46 evaluable patients (localassessment; two pCRs verified only by core biopsy) (p=0.22 and p=0.06 for nullhypothesis, respectively). Despite HER2-E subtype, no pCR was observed in the 4patients with immunohistochemical (IHC) HER2 2+/ISH-positive status in contrastto 20/39 (51.2%) pCRs in IHC HER2 3+ tumors. Centrally confirmed pCR rate in HR+/HER2+tumors was38.5% compared to 58.5% in HR-/HER2+ tumors. No new safety signals wereobserved. Conclusions: These are the first results of a neoadjuvant chemotherapy-free12-week de-escalation anti-HER2-regimen with trastuzumab and pertuzumab incombination with the PD-1 inhibitor pembrolizumab in patients with a HER2-E EBC.In the context of the WSG ADAPT HER2+ de-escalation trials the observed pCRrates compare favourably in HR+ as well as HR- HER2 EBC. Moreover, KEYRICHED-1demonstrates that with appropriate molecular patient selection clinicallymeaningful pCR rates in the range of those obtained with longer, more toxicchemotherapy-containing regimens can be achieved. Citation Format: Sherko Kuemmel, Oleg Gluz, Mattea Reinisch, Athina Kostara, Iris Scheffen, Monika Graeser, Kerstin Luedtke-Heckenkamp, Andreas Hartkopf, Felix Hilpert, Angela Kentsch, Carsten Ziske, Reinhard Depenbusch, Michael Braun, Jens Blohmer, Christine zu Eulenburg, Matthias Christgen, Stephan Bartels, Hans Kreipe, Enrico Pelz, Peter Schmid, Nadia Harbeck. KEYRICHED-1 - A prospective, multicenter, open label, neoadjuvant phase II single arm study with pembrolizumab in combination with dual anti-HER2 blockade with trastuzumab and pertuzumab in early breast cancer patients with molecular HER2-enriched intrinsic subtype [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 P2-13-03.

Abstract PD15-02: HER2-enriched subtype and novel molecular subgroups drive aromatase inhibitor resistance and an increased risk of relapse in early ER+/HER2+ breast cancer

Abstract Background: Approximately 10% of estrogen receptor positive (ER+) early breast cancers (EBC) are human epidermal growth factor positive/overexpressed (HER2+). Resistance to aromatase inhibitors (AIs) is poorly understood among ER+HER2+ BC. We aimed to identify biomarkers of response and resistance using the HER2+ tumours in the POETIC trial. Methods: POETIC was a phase III trial of post-menopausal women with ER+ EBC randomized 2:1 to 2-weeks of peri-surgical AI vs control, followed by standard-of-care. Baseline formalin-fixed paraffin-embedded samples from 342 ER+HER2+ BC (237 treated/105 controls) were gene expression profiled using Breast cancer 360™ panel (NanoString) covering intrinsic subtypes and 40 key biological signatures. New molecular subgroups were identified using consensus clustering (CC).Proliferation rate was estimated as percentage of cancer-cells staining for Ki67. Ki67 response was defined by percentage-changes from baseline to surgery: poor (PR; reduction &amp;lt;50%), intermediate (IR; 50-75%) and good (GR; &amp;gt;75%). Residual Ki67 at 2 weeks timepoint (Ki672w) was defined as High (H) (≥ 10%) vs Low (L) (&amp;lt;10%). Association of molecular features with Ki67 response was assessed using logistic regression models and with time to recurrence (TTR) using multivariable Cox regression models adjusted for post-surgery clinicopathological variables: grade, tumour size, nodal status and age. Results: Ki672w was measured for all treated samples (n = 227, 48% H, 52% L) and a fraction of controls (n = 50, 96% H, 4% L). At baseline, 45% of tumours were HER2-enriched (HER2-E), 53% Luminal A/B and 2% Basal-Like. HER2-E associated with high Ki672W (84% H, 16% L) compared to non-HER2-E (29% H, 71% L, p&amp;lt;0.001). Amongst the 40 BC360 signatures, 9 were significantly associated with Ki67 response (Table). High expression of endocrine-related and apoptosis signatures associated with GR while HRD and TP53 with PR. These features were also related to Ki672W, with additional signatures involved in immune-checkpoint component and immune-enrichment (IM) (IDO1, PD-L1, IFN-gamma and T-reg) associated with high Ki672W.. Using CC, 4 molecular subgroups predicting differential response to AI were identified. Cluster (C) 1 was characterized by overexpression of IM features and low ER signaling (42%); C2 low IM but highest ERBB2 expression (15%); C3 ESR1 high and PgR low (4%) and C4 high endocrine signaling and lowest ERBB2 expression (39%). Distribution of Intrinsic subtypes varied across these molecular subgroups with the majority of C1 being HER2-E (62%) and Luminal B (27%); C2 HER2-E (74%); C3 Luminal B (64%) and C4 Luminal B (55%) and Luminal A (30%). HER2-E had significantly poorer TTR (HR 2.14; 95%CI1.11-4.17; p=0.0224) compared to Luminal tumours, remaining significant (HR 2.55, 95%CI1.14-5.69; p=0.0222) in the multivariable analysis. C2 (HR 4.67, 95%CI 1.90-11.51; p&amp;lt;0.001) and C4 (HR 2.42, 95%CI1.05-4.5.58; p=0.0385) were independent predictors of shorter TTR compared to C1, adding significant value beyond intrinsic subtypes (Likelihood ratio test, p=0.00429). Conclusions: Our results confirm that HER2-E, TP53 mutation, HRD and IM features are the main components driving poor early response to AI in ER+/HER2+ EBC. Novel molecular subgroups identify additional non-HER-E tumours not responding to AI with an increased risk of relapse. The appropriate additional treatment warrants further investigation. List of significant gene expression signatures associated with response as defined by reduction of Ki67. Odds ratio (OR) were determined by ordinal logistic regression analyses. OR: &amp;lt;1 indicating associated with good response and &amp;gt; 1.0 associated with worse response.Odds Ratiop-valuep-adjusted (False Discovery Rate)ESR10.65&amp;lt; 0.001&amp;lt; 0.001Estrogen Receptor Signaling0.44&amp;lt; 0.001&amp;lt; 0.001ERBB21.52&amp;lt; 0.001&amp;lt; 0.001TP53 mutant signature2.65&amp;lt; 0.001&amp;lt; 0.001FOXA10.42&amp;lt; 0.001&amp;lt; 0.001Apoptosis0.26&amp;lt; 0.0010.00228Homologous Recombination Deficiency (HRD)2.33&amp;lt; 0.0010.00349PgR0.820.001480.00737Hypoxia2.180.001660.00737 Citation Format: Milana A Bergamino Sirvén, Elena López-Knowles, Gabriele Morani, Holly Tovey, Lucy Kilburn, Chris Holcombe, Anthony Skene, Ian Smith, John Robertson, Gene Schuster, Judith M Bliss, Mitch Dowsett, Maggie CU Cheang, POETIC investigators. HER2-enriched subtype and novel molecular subgroups drive aromatase inhibitor resistance and an increased risk of relapse in early ER+/HER2+ breast cancer [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 PD15-02.

Abstract ES1-1: Escalating and de-escalation - titrating the right regimen in early stage HER2 positive

Abstract In HER2+ early breast cancer (EBC), treatment concepts so far do not differ according to hormone receptor (HR) status except for adding adjuvant endocrine therapy (ET) in HR+. Nevertheless, preclinical research shows that molecular subtype distributions differ between HR+ and HR- HER2+ with HER2-enriched subtype being more frequent in HR-. In the context of anti-HER2 therapy the clinical impact of biomarkers such as PIK3CA mutations also differs between HR+ and HR-. Moreover, in the neoadjuvant setting, pCR rates differ between HR+ and HR- HER2+ EBC with lower rates in HR+. Yet, the prognostic impact of pCR on outcome in HR+ HER2+ is less pronounced than in HR- HER2+ tumors. Standard therapy for small tumors (pT1 pN0) includes primary surgery followed by adjuvant weekly paclitaxel and 1y trastuzumab, independent of HR status. In all larger node-negative and in node-positive tumors, neoadjuvant chemotherapy with dual HER2 blockade is recommend. Adjuvant therapy is then individualized based on pCR status with antibody therapy continued for 1y in case of pCR and 14 cycles of T-DM1 in case of non-pCR. Based on the ExteNET trial, 1y neratinib is approved as an extended adjuvant anti-HER2 therapy. In Europe, the approval is restricted to high-risk HR+ HER2+ EBC within 1y after trastuzumab therapy based on ExteNET subgroup analyses. Escalation of the endocrine component in high-risk HR+ HER2+ EBC is currently evaluated in eMonarcHER2 by adding abemaciclib to T-DM1 and ET after non-PCR. Regarding de-escalation, TBCRC0023, one of the first chemotherapy-free de-escalation studies in HER2+ EBC, looked at duration of neoadjuvant trastuzumab and lapatinib - in HR+ tumors together with letrozole (+ GNRH if premenopausal). Longer therapy duration led to higher in-breast pCR rates, particularly in the ER+ subgroup (33% after 24 vs. 9% after 12 weeks). WSG ADAPT was the first subtype-specific umbrella trial aiming at tumor-biology adapted therapy de-escalation in EBC; all neoadjuvant sub-trials evaluated 12 weeks of preoperative therapy and allowed patients with a pCR to omit further standard chemotherapy. For HR+/HER2+, there are two neoadjuvant trials, ADAPT TP (triple-positive) and TP II, so far. In ADAPT TP, 4x T-DM1 led to a total pCR (breast and nodes) of 41% - independent of concomitant ET, whereas trastuzumab + ET only rendered 15%. pCR was prognostic for outcome; in patients with pCR, further standard chemotherapy did not improve survival. In TP II, 12x weekly paclitaxel + trastuzumab + pertuzumab achieved a total pCR rate of 57%, whereas the antibodies alone + ET rendered 24%. Individualizing therapy by escalation or de-escalation holds great promise in HER2+ EBC, but the full potential of taking HR-status into account for such strategies has not yet been explored. We now know that a pCR achieved with a de-escalated regimen is clinically meaningful and that de-escalation trials are safe for participating patients in HR+ HER2+ EBC - provided patients and physicians have the option for therapy escalation if clinically needed. The neoadjuvant strategy offers an ideal setting for de-escalation and escalation concepts based on pCR status as well as on early response assessment by biomarkers and conventional or molecular imaging. Optimal endpoints in HR+ HER2+ disease differ according to molecular subtype. As demonstrated in ADAPT TP, HER2-enriched subtype is associated with high pCR rates after HER-targeting regimens whereas luminal A and B subtypes have lower pCR rates. In luminal tumors, survival endpoints may thus be more appropriate to fully evaluate de-escalated regimens.In clinical routine, individualized therapy concepts including therapy de-escalation and escalation should always be evidence-based in order not to jeopardize the already excellent survival rates we have achieved over the last decade in HR+ HER2+ EBC. Citation Format: Escalating and de-escalation - titrating the right regimen in early stage HER2 positive [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 ES1-1.

Abstract ES1-2: Genomics of HER2+ breast cancer

Abstract Human epidermal growth factor receptor 2 (HER2) is amplified and overexpressed in about 20% ofall breast cancers and, when untreated, is the most aggressive breast cancer phenotype. The prognosis of patients with HER2-positive breast cancer has been markedly improved thanks to the effectiveness of anti-HER2 therapies. However, we still overtreat a high proportion of patients with toxic chemotherapy +antiHER2 combinations, while others still develop recurrent disease despite these complex regimens. Both the intrinsic complexity of HER2-positive tumors and the properties of its tumor microenvironment likely contribute to differences in response toanti-HER2 targeted therapies. HER2-positive breast cancer is highly heterogeneous, and all the intrinsic molecular subtypes can be identified within HER2-positive tumors by gene expression. HER2-enriched subtype has been systematically associated with higher pCR rates to anti-HER2 targeted therapies across multiple trials in early stages. Genomically, the HER2-enriched subtype is the most HER2 oncogene addicted of the subtypes, which likely explains the high sensitivity to anti-HER2 therapies. However, this may also explain why a HER2-enriched tumor with residual disease after anti-HER2 treatments carries a particularly poor prognosis. Conversely, both tumor-infiltrating lymphocytes (TILs) and RNA-based immune-signatures are significantly and independently associated with a higher likelihood of pCR and better survival outcomes in patients with HER2-positive disease. Thus, integrating the prognostic information provided by clinical factors, genomic subtype, and immune-related signatures is essential to improve the design of future clinical trials and establish new and better treatment algorithms for HER2-positive breast cancer treatment. Citation Format: C Perou. Genomics of HER2+ breast cancer. [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 ES1-2.