HER2 Negative Subtypes Research Articles

The role of a «short-term» preoperative endocrine therapy for adjuvant therapy guidance in early HR+ HER2-negative breast cancer

In the absence of widespread access to genomic tests there is an urgent need for additional methods that influence the choice of adjuvant therapy in patients with early luminal Her2-negative subtype of breast cancer (BC). The IMPACT and POETIC trials have shown that Ki67 level decrease up to ≤10% after a “short-term” (2–4 weeks) preoperative endocrine therapy (ET) is a favorable prognostic factor. This test allows some patients to avoid adjuvant chemotherapy associated with immediate and delayed adverse events.Aims of the study. To evaluate the impact of “short-term” preoperative endocrine therapy for guidance of further treatment for patients with primary operable luminal Her2-negative breast cancer stages T1–3 N0–1 M0.Results. The study included 123 patients, 76 (60.8%) received tamoxifen and 47 (37.6%) – aromatase inhibitors (AI). Most patients – 69 (55.2%) were >50 years old, premenopausal – 58 (46.4%), menopausal – 67 (53.6%). The average age was 52 years (30–82). With the initial Ki67 level>10% (N= 107), Ki67 decreased in 24 (22.4%) up to ≤10% after “short-term” ET, and remained >10% in 83 (77.6%). According to the PREDICT calculator, the benefit of adjuvant chemotherapy (AChT) was assessed as high in 35 (28.5%) patients, and 10 of them (27.8%) were able to avoid Ch T. In 86 patients with a relatively low estimated AChT benefit (<5% at 10 years) there was no response to “short-term” ET, which led to the AChT prescription in 13 cases (15.1%).Conclusions. “Short-term” course of preoperative endocrine therapy is a simple, accessible and reproducible method for personalizing of adjuvant therapy in patients with luminal HER2-negative breast cancer.

Evaluating the Effectiveness of Cyclin-Dependent Kinase 4/6 Inhibitors in Early- and Very Early-Onset Metastatic Breast Cancer: A Multicenter Study.

Background and Objectives: Early-onset breast cancer (EOBC), particularly in patients under 40, presents with distinct biological characteristics and worse survival outcomes compared to late-onset cases. Despite intensive treatments, EOBC patients, especially those with hormone receptor-positive, HER2-negative (HR+/HER2-) subtypes, show poorer prognosis. CDK4/6 inhibitors, combined with endocrine therapy (ET) have become the standard for HR+/HER2- metastatic breast cancer, yet younger patients are underrepresented in clinical trials. This study aims to evaluate the efficacy of ribociclib and palbociclib with ET in HR+/HER2- metastatic breast cancer, addressing the critical gap in understanding treatment outcomes in younger patient populations. Materials and Methods: This multicenter, retrospective study evaluated the efficacy and safety of cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitors, ribociclib, and palbociclib, in combination with endocrine therapy in patients with hormone receptor-positive and human epidermal growth factor receptor 2-negative metastatic breast cancer. Results: A total of 198 patients treated between 2019 and 2023 were analyzed for progression-free survival, overall survival, and prognostic factors. Very early-onset breast cancer, which is diagnosed before the age of 35, was identified as an independent prognostic factor for poor progression-free survival. Additional factors associated with poorer outcomes included liver metastasis, progesterone receptor negativity, high tumor grade, and the concurrent use of fulvestrant with CDK4/6 inhibitors. Both ribociclib and palbociclib demonstrated similar efficacy, and dose reductions due to treatment-related adverse events did not compromise therapeutic outcomes. Conclusions: This study is the first to focus specifically on the treatment of early-onset breast cancer with CDK4/6 inhibitors, providing critical insights into the unique challenges faced by this patient population. The findings underscore the urgent need for personalized treatment strategies, routine genetic testing, and dedicated clinical trials designed to address the specific needs of these high-risk subgroups. By advancing our understanding of the clinical and molecular landscape of early-onset breast cancer and very early-onset breast cancer, this study lays the groundwork for improving outcomes in these underserved patients through tailored therapeutic approaches.

Neoadjuvant chemotherapy and pathological complete response in hormone-positive HER2-negative breast cancer: influence of progesterone receptor expression, tumor grade and Ki-67

Aim. To study the role of progesterone receptor expression, tumor grade and Ki-67 level as possible predictors of pathological complete response (pCR) to neoadjuvant chemotherapy in patients with stage IIA–IIB (cT1–2N1, cT2–3N0M0) breast cancer of hormone-positive HER2-negative subtype.Materials and methods. We retrospectively analysed the efficacy of neoadjuvant chemotherapy (4AC+12P/4T) in 100 patients with cancer stages IIA–IIB (cT1–2N1, cT2–3N0M0) of hormone-positive HER2-negative subtype treated at the P.A. Hertsen Moscow Oncology Research Institute from 2013 to 2022. The pathological response to neoadjuvant chemotherapy depending on the level of progesterone receptor expression, tumour grade (G) and tumour proliferation index (Ki-67) were evaluated.Results. Pathological complete response was achieved in 12 of 100 patients. The progesterone receptor expression ≤3 Allred pCR scores were found in 16.1 % (5/31) of patients, whereas with progesterone receptor >3 scores in 10.1 % (7/69) (odds ratio 1.703; 95 % confidence interval (CI) 0.495–5.860; p = 0.507). Patients with high tumour grade (G3) achieved pCR in 12.1 % (4/33) cases and with G2 – in 11.9 % (8/67) (odds ratio 1.017; 95 % CI 0.283–3.658; p = 1.000). With the Ki-67 levels ≥50 % pCR was achieved in 14.6 % (7/48) cases compared to 9.6 % (5/52) with Ki-67 levels <50 %(odds ratio 1.605; 95 % CI 0.473–5.445; p = 0.544). The Ki-67 threshold for achieving pCR was 70 % (area under the ROC curve 0.663 ± 0.090; 95 % CI 0.486–0.840; p = 0.068) and for progesterone receptors was 3 points (area under the ROC curve 0.625 ± 0.080; 95 % CI 0.467–0.782; p = 0.156).Conclusion. This analysis highlights the importance of considering all clinical and morphological characteristics of the tumour when planning the scope of treatment for hormone-positive HER2-negative breast cancer. The results obtained may serve as a basis for a more personalised therapeutic approach.

Genetic heterogeneity and metabolic reprogramming in breast cancer

Breast cancer is the most prevalent cancer and the leading cause of cancer-related mortality among women. Recent breakthroughs in breast cancer therapeutics have significantly enhanced outcomes for hormone receptor-positive and HER2-negative subtypes. However, the emergence of drug resistance, particularly in triple-negative breast cancer, presents a formidable challenge. The intricate interplay of genetic and metabolic diversity within breast cancer cells is pivotal to its development. By reprogramming metabolic pathways, cancer cells can adapt and thrive, meeting the demands of survival, growth, and invasion. These metabolic shifts also play a key role in the development of resistance to conventional therapies. This review explores the genetic and metabolic complexities of breast cancer, emphasizing the diverse subtypes and their unique profiles. We examine how genetic variations and metabolic alterations contribute to breast cancer development and progression, influencing both treatment efficacy and resistance. By integrating insights into the genetic background and metabolic reprogramming of breast cancer subtypes, this review aims to highlight the genetic variations and metabolic alterations that contribute to the pathogenesis of breast cancer, with a vision of advancing more precise and effective targeted therapies as well as discovering of novel diagnostic and prognostic markers.

Diffusion-weighted imaging based on intravoxel incoherent motion: correlation with molecular prognostic factors and subtypes in breast cancer.

Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI), which indicates biological tissue attributes, may be applied to accurately assess breast tumors. To analyze the IVIM parameters of different molecular prognostic factors and subtypes to find out whether there are any connections. A total of 181 patients enrolled in this retrospective study had preoperative magnetic resonance imaging (MRI) examinations, and pathologies were verified as breast cancers. Regions of interest were placed at all slices of the parameter maps (D, tissue diffusivity; ADC, apparent diffusion coefficient; f, perfusion fraction; and D*, pseudo-diffusivity maps) of IVIM and generated parameter values to be used for comparative analysis among molecular prognostic factors and subtypes. D and ADC were greater in estrogen receptor (ER)-negative, human epidermal growth factor receptor 2 (HER2)-positive, and Ki67-low expression groups (all P values < 0.05). The progesterone receptor (PR)-negative group had a higher D value (P < 0.05). f was larger in the lymph node metastasis-negative group and the PR-positive group (P = 0.012 and 0.046, respectively). Among breast cancer subtypes, D and ADC were different between the HER2-overexpression and the Luminal B (HER2-negative) subtypes (P = 0.019 and 0.028, respectively). The difference in D between the luminal and non-luminal subtypes was statistically significant (P = 0.008). The triple-negative subtype significantly differs from the other subtypes in D* and f (P = 0.012 and 0.016, respectively). IVIM-related metrics exhibited relationships with breast cancer molecular prognosis factors and subtypes.

Characteristics of stem sings of EpCAM-negative and EpCAM-positive tumor cells in primary tumor and 2D and 3D cultures in breast cancer

One of the predictors of adverse prognosis in breast cancer is the overexpression of the EpCAM protein. However, a signifcant part of tumor cells have low or no EpCAM expression. The molecular features and the ability to grow in 2D and 3D cultures, indirectly refecting metastatic potential of tumor cells without EpCAM expression, have not been sufficiently studied.The aim of the study was to compare phenotypic variants of stem cells and EMT depending on the EpCAM expression in the primary tumor of breast cancer and 2D and 3D cultures.Material and Methods. The study included 7 patients with invasive breast carcinoma of no special type. Luminal A subtype was found in 2/7 patients (29 %), and luminal B HER2-negative molecular subtype was found in 5/7 patients (71 %). The patients didn’t have neoadjuvant chemotherapy. Cells from the primary tumor were cultured in 2D and 3D. The primary tumor cells, 2D and 3D cultures were phenotyped using fow cytometry with antibodies targeting: CD45, EpCAM (CD326), CD44, CD24, N-cadherin (CD325), and CD133, CK7/8, EpCAM (CD326).Results. No significant differences were found in the frequency of detection and the number of cells exhibiting stem cell features among EpCAM- and EpCAM+ tumor cells, 2D and 3D cultures. All phenotypic variants of co-expression of stemness markers CD44, CD24, CD133, and ALDH were present both in the primary tumor and 2D/3D cultures. Stem cells in mammospheres had features of both epithelial and hybrid EMT phenotypes. In primary tumors and 2D/3D cultures, the smallest proportion consisted of stem cells with the CD44+CD24- phenotype and cells co-expressing CD44+CD24- with other stemness markers, while the largest proportion comprised stem cells with ALDH+ and ALDH+CD133+ phenotypes. Marked intra- and inter-tumor heterogeneity in the phenotypic composition of primary tumors, 2D, and 3D cultures was noted.Conclusion. The results indicate that EpCAM-negative and EpCAM-positive tumor cells of luminal molecular subtype of breast cancer are capable of exhibiting various phenotypic variants of stemness and EMT in the primary tumor and 2D and 3D cultures. In most cases, individual tumor cells show co-expression of several stemness markers. The phenotypic composition of primary tumors, 2D and 3D cultures is characterized by pronounced intra- and inter-tumor heterogeneity.

Magnetic resonance imaging-guided single-fraction preoperative radiotherapy for early-stage breast cancer (the RICE trial): feasibility study

BackgroundOver the past decade, the adoption of screening programs, digital mammography, and magnetic resonance imaging (MRI) has increased early-stage breast cancer diagnosis rates. Mortality rates have decreased due to early detection and improved treatments, including personalized therapies. Accelerated partial-breast irradiation (APBI) is emerging as a convenient and effective treatment for some patients, with studies exploring its preoperative use. Preoperative APBI, especially with MRI guidance, offers improved tumor targeting and potentially reduced side effects. Magnetic Resonance Imaging-Guided Single-Fraction Pre-Operative Radiotherapy for Early-Stage Breast Cancer (RICE trial) aims to assess the feasibility and efficacy of MRI-guided single-dose radiotherapy (RT) for early-stage breast cancer.MethodsThe RICE study is a prospective, single-arm study evaluating single-fraction preoperative, APBI treatment for patients with early-stage breast cancer using a magnetic resonance imaging linear accelerator (MRI linac). Eligible patients enrolled in this study will have a core biopsy to confirm estrogen receptor-positive and HER2-negative sub-type. RT planning will use a planning computed tomography (CT) co-registered with a MRI with the patient in either the supine or prone position. For the diagnostic workup, [18F] fluorodeoxyglucose positron emission tomography/CT ([18F] FDG PET/CT) and [18F] fluoroestradiol positron emission tomography/CT ([18F] FES PET/CT) will be performed prior to treatment. Thirty patients will receive a single ablative RT dose of 21 Gray to the tumor. Pre-treatment and post-treatment MRI scans will be acquired at baseline and 5 weeks post-RT respectively. Breast-conserving surgery will be scheduled for 6 weeks after APBI treatment using the MRI linac.The primary study endpoint is the successful administration of a single fraction of preoperative breast RT under the guidance of an MRI linac. Secondary endpoints include evaluating the utility of MRI, [18F] FDG PET/CT, and [18F] FES PET/CT as a non-invasive method for assessing treatment response in patients undergoing single-fraction preoperative APBI.ConclusionThe RICE trial represents a significant step in breast cancer treatment, offering insights that could lead to treatment protocols with minimized RT appointments and enhanced patient outcomes.Trial registrationThis trial is registered with the Australian New Zealand Clinical Trials Registry (ANZCTR). Registered 31st of May 2021. Registration number: ACTRN12621000659808.

Datopotamab-deruxtecan plus durvalumab in early-stage breast cancer: the sequential multiple assignment randomized I-SPY2.2 phase 2 trial.

Sequential adaptive trial designs can help accomplish the goals of personalized medicine, optimizing outcomes and avoiding unnecessary toxicity. Here we describe the results of incorporating a promising antibody-drug conjugate, datopotamab-deruxtecan (Dato-DXd) in combination with programmed cell death-ligand 1 inhibitor, durvalumab, as the first sequence of therapy in the I-SPY2.2 phase 2 neoadjuvant sequential multiple assignment randomization trial for high-risk stage 2/3 breast cancer. The trial includes three blocks of treatment, with initial randomization to different experimental agent(s) (block A), followed by a taxane-based regimen tailored to tumor subtype (block B), followed by doxorubicin-cyclophosphamide (block C). Subtype-specific algorithms based on magnetic resonance imaging volume change and core biopsy guide treatment redirection after each block, including the option of early surgical resection in patients predicted to have a high likelihood of pathologic complete response, which is the primary endpoint assessed when resection occurs. There are two primary efficacy analyses: after block A and across all blocks for six prespecified HER2-negative subtypes (defined by hormone receptor status and/or response-predictive subtypes). In total, 106 patients were treated with Dato-DXd/durvalumab in block A. In the immune-positive subtype, Dato-DXd/durvalumab exceeded the prespecified threshold for success (graduated) after block A; and across all blocks, pathologic complete response rates were equivalent to the rate expected for the standard of care (79%), but 54% achieved that result after Dato-DXd/durvalumab alone (block A) and 92% without doxorubicin-cyclophosphamide (after blocks A + B). The treatment strategy across all blocks graduated in the hormone-negative/immune-negative subtype. No new toxicities were observed. Stomatitis was the most common side effect in block A. No patients receiving block A treatment alone had adrenal insufficiency. Dato-DXd/durvalumab is a promising therapy combination that can eliminate standard chemotherapy in many patients, particularly the immune-positive subtype.ClinicalTrials.gov registration: NCT01042379 .

Exploring the value of FAP-targeted PET/CT in differentiating breast cancer molecular subtypes: a preliminary study.

This prospective study aims to evaluate the value of [18F]AlF-NOTA-fibroblast activation protein inhibitor (FAPI)-04 positron emission tomography-computed tomography (PET/CT) in predicting molecular subtypes of breast cancer. The study consecutively recruited patients suspected of having breast cancer from a single center who were prospectively enrolled from July 2023 to May 2024 and underwent [18F]AlF-NOTA-FAPI-04 PET/CT. This study compared the differences in tracer uptake among breast cancers with different adverse prognostic factors and molecular subtypes. The classification performance for each molecular subtype of breast cancer was assessed using a receiver operating characteristic (ROC) curve. Fifty-three participants (mean age, 51 ± 11 years; 52 females) were evaluated. Breast cancer lesions with adverse prognostic factors showed higher tracer uptake. The five different molecular subtypes exhibited varying levels of uptake. The luminal A and luminal B (HER2-negative) subtypes had relatively low uptake, while the luminal B (HER2-positive), HER2-positive, and triple-negative subtypes had relatively high uptake. ROC analysis identified the max standardized uptake value (SUVmax) as a significant classifier (AUC = 0.912, P = 0.0005) for the luminal A subtype, with 100% sensitivity and 83% specificity. For predicting the luminal B (HER2-negative) subtype, SUVmax had an AUC of 0.770 (P = 0.0015). SUVmax, with an AUC of 0.781 (P = 0.003), was used to identify the triple-negative subtype tumors, resulting in a sensitivity of 100% and specificity of 51%. Lastly, the ROC curve showed the cut-off 15.40 (AUC = 0.921, P < 0.0001) could classify luminal A & luminal B (HER2-negative), and luminal B (HER2-positive) & HER2-positive & triple-negative, yielding a sensitivity of 94% and specificity of 79%. The uptake of [18F]AlF-NOTA-FAPI-04 is significantly correlated with the molecular subtypes of breast cancer, and [18F]AlF-NOTA-FAPI-04 PET/CT is a potential tool for noninvasive identification of luminal A subtypes and guidance of FAP-targeted therapies.

Expanding the treatment options for HER2-low metastatic breast cancer: Experience with trastuzumab deruxtecan in aggressive luminal HER2-low breast cancer

The polar division of breast cancer into HER2-positive and HER2-negative subtypes has long remained clinically significance. However, up to 60% of HER2-negative tumors have HER2 receptor expression assessed by immunohistochemistry as 1+ or 2+. In the absence of gene amplification, such tumors are classified as HER2-low. Сlassical anti-HER2 agents have not improved treatment outcomes for these tumors. The development of a new generation antibody-cytostatic conjugate, trastuzumab deruxtecan, targeting the HER2 receptor, is changing diagnostic approaches and clinical practice in the treatment of metastatic HER2-low breast cancer. The results of the phase III DESTINY-Breast04 study of trastuzumab deruxtecan in patients with metastatic breast cancer with low HER2 expression became a real revolution. The median progression-free survival in the cohort of patients receiving trastuzumab deruxtecan was 9.9 months versus 5.1 months in the group of patients receiving standard chemotherapy at the physician’s choice (RR 0.50; 95% CI 0.40–0.63, P = 0.003). An objective response during therapy with trastuzumab deruxtecan was recorded in 52.3% of cases versus 16.3% in the standard treatment group. Therapy with the new drug demonstrated a favorable safety profile and did not reduce the quality of life. In this publication, we present our own experience of treating a patient with metastatic luminal HER2-low breast cancer with trastuzumab deruxtecan. Despite the aggressive course, the number of previous lines of therapy and massive liver damage, the use of trastuzumab deruxtecan made it possible to control the disease for 2 years while maintaining a high quality of life for the patient. Trastuzumab deruxtecan is a new effective treatment option for HER2-low metastatic breast cancer.

Identification of peripheral blood test parameters predicting the response to palbociclib and endocrine therapy for metastatic breast cancer: a retrospective study in a single institution

PurposeCyclin-dependent kinase 4/6 inhibitors have been used in endocrine therapy for patients with estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer. Although randomized trials have shown that combined therapies prolong progression-free survival (PFS) in comparison to endocrine monotherapy, the predictors of efficacy are unknown. This study aimed to identify the blood test parameters to predict the effects of palbociclib and endocrine therapy.MethodsSeventy-nine patients treated with palbociclib and endocrine therapy between December 2017 and June 2022 were reviewed. We assessed PFS in patients according to factors evaluated based on patient characteristics and peripheral blood tests.ResultsPatients in the C-reactive protein (CRP)-high, lactate dehydrogenase (LDH)-high, and albumin (Alb)-low groups had significantly shorter PFS than those in the normal group. A multivariate analysis revealed that high LDH and low Alb levels were independent factors that affected PFS. The Alb-low group had an inferior disease control rate. Patients in the CRP-high, LDH-high, and Alb-low groups who received these therapies as first- or second-line treatments showed poor PFS.ConclusionsSeveral predictors of the efficacy of palbociclib and endocrine therapy were identified in the peripheral blood test parameters of patients with ER-positive and HER2-negative subtypes of metastatic breast cancer.

Polymorphic variants of the hOGG1, APEX1, XPD, SOD2, and CAT genes involved in DNA repair processes and antioxidant defense and their association with breast cancer risk.

Breast cancer is one of the leading causes of mortality among women. The most frequently encountered tumors are luminal tumors. Associations of polymorphisms in the hOGG1 (rs1052133), APEX1 (rs1130409), XPD (rs13181), SOD2 (rs4880), and CAT (rs1001179) genes were studied in 313 nonsmoking postmenopausal patients with luminal B subtype breast cancer. The control group consisted of 233 healthy nonsmoking postmenopausal women. Statistically significant associations of the XPD and APEX1 gene polymorphisms with the risk of developing luminal B Her2-negative subtype of breast cancer were observed in a log-additive inheritance model, while the CAT gene polymorphism showed an association in a dominant inheritance model (OR = 1.41; CI 95 %: 1.08-1.85; Padj.= 0.011; OR = 1.39; CI 95 %: 1.07-1.81; Padj = 0.013 и OR = 1.70; CI 95 %: 1.19-2.43; Padj = 0.004, respectively). In the group of elderly women (aged 60-74 years), an association of the CAT gene polymorphism with the risk of developing luminal B subtype of breast cancer was found in a log-additive inheritance model (OR = 1.87; 95 % CI: 1.22-2.85; Padj = 0.0024). Using MDR analysis, the most optimal statistically significant 3-locus model of gene-gene interactions in the development of luminal B Her2-negative subtype breast cancer was found. MDR analysis also showed a close interaction and mutual enhancement of effects between the APEX1 and SOD2 loci and the independence of the effects of these loci from the CAT locus in the formation of luminal B subtype breast cancer.

Differential genomic profiling of the progesterone receptor (PR) negative and estrogen receptor (ER) low metastatic breast cancer subtypes through circulating tumor DNA: A TNBC-like disease subtype?

1039 Background: ER positive/HER2 negative metastatic breast cancer (MBC) is typically regarded as a single entity, although significant clinical differences are often observed, especially in the ER low subgroup (ER&lt;10% regardless of PR status). This study aims to investigate genomic differences among HER2 negative subtypes (i.e., ERlow, PRpos [ER &gt;10%/PRpositve], PRneg [ER &gt;10%/PRnegative], triple negative [TNBC]) through circulating tumor DNA (ctDNA) next-generation sequencing (NGS). Methods: The study analyzed a retrospective cohort of 879 patients (pts) with HER2 negative MBC with ctDNA testing using the Guardant360 NGS panel within a large multicenter academic consortium. ER, PR and HER2 status was defined based on the most updated biopsy. Associations across single nucleotide and copy number variations (SNVs and CNVs) and ER/PR status were tested by multinomial logistic regression in terms of Relative Risk Ratio (RRR), adjusting for significant clinical characteristics (i.e., lines of treatment, metastatic sites, histology). Oncogenic pathway was defined based on reference (1). Prognosis was analyzed through Cox regression for overall survival (OS) defined from time of ctDNA collection. Results: Among the 879 analyzed pts, PRpos was the most prevalent subtype (N:420, 48%), followed by PRneg (N:216, 24%), TNBC (N:209, 24%), and ERlow (N:34, 4%). Compared to PRpos, lobular MBC was less common in TNBC (RRR: 0.33, P=0.001), while lung involvement was more frequent in TNBC (RRR: 1.53, P=0.019), and liver involvement in PRneg (RRR: 1.44, P=0.035). In contrast, bone metastases were less common in TNBC and ERlow (RRR: 0.26, P&lt;0.001 and RRR: 0.45, P=0.03, respectively). After multivariable analysis, ERlow and TNBC were associated with a higher incidence of TP53 SNVs (RRR: 5.42, P&lt;0.001 and RRR: 3.08, P=0.007, respectively) and a lower incidence of ESR1 SNVs (RRR: 0.23, P=0.025 and not detected, respectively). TNBC exhibited significantly fewer PIK3CA SNVs (RRR: 0.41, P=0.005) and CCND1 CNVs (RRR: 0.20, P=0.009), along with a higher frequency of CCNE1 CNVs (RRR: 6.47, P&lt;0.001). PRneg had a lower incidence of ESR1 SNVs (RRR: 0.52, P=0.013) and more frequent FGFR1 CNVs (RRR: 2.61, P=0.004). Similar results were observed across oncogenic pathways. Compared to PRpos, OS analysis indicated poorer outcomes across all subgroups (PRneg HR: 1.29 P = 0.035, TNBC HR: 1.96 P&lt;0.001, ERlow HR: 2.32 P&lt;0.001). Conclusions: This study highlights several clinical and molecular similarities between TNBC and ERlow MBC, while suggesting specific endocrine resistance mechanisms in PRneg that are less reliant on ESR1 and more exposed to alternative mechanisms such as FGFR1 amplification. These findings underscore the importance of more precise disease subtyping to inform future drug development trials. 1. Sanchez-Vega F et al, Cell. 2018.

Frequency of HER2-Low in breast cancer biopsies in Chile.

e13163 Background: In breast cancer (BC), human epidermal growth factor receptor 2 (HER2) is a prognostic and predictive biomarker. Traditionally, the use of HER2-targeted therapies is reserved for BC that overexpress HER2, defined as immunohistochemical (IHC) expression of 3+ or 2+ with amplification of the gene encoding HER2, detected by in situ hybridization (ISH). Recently, the term HER2-Low, defined as the IHC expression of 1+ or 2+ with negative ISH, has gained relevance as a new predictive biomarker for the use of trastuzumab-deruxtecan. The frequency of HER2-Low BC in the Chilean population is unknown. The objective of this study is to show the frequency of HER2-Low BC in a Chilean center. Methods: Descriptive cross-sectional analysis of clinical records and biopsies of localized or metastatic invasive breast carcinoma performed at Clínica Santa María between January 2020 and December 2023. The IHC expression of the estrogen receptor (ER), progesterone receptor (PR), Ki-67, HER2, histological grade (G) and HER2 in situ hybridization (ISH) when appropriate. The frequency and characteristics of HER2-Low cases are described and compared with the surrogate clinicopathological subtypes luminal A, luminal B (HER2-Positive and Negative), HER2-Positive and Triple Negative (TN), according to the St Gallen Consensus Conference 2013. Results: Between January 2020 and December 2023, a total of 339 biopsies with invasive BC were identified, from which 104 (36.0%) met the definition of HER2-Low. The frequency of luminal B and luminal A that met the definition of HER2-Low was 54 (51.9%) and 40 (38.5%), respectively. Of the 253 biopsies classified as luminal, 94 (37.2%) met the definition of HER2-Low, while of the 36 biopsies classified as TN, 10 (27.8%) did. Luminal B HER2-Negative and TN surrogate subtypes that met the definition of HER2-Low had a higher frequency of G3 than their non-HER2-Low counterpart. Conclusions: In the population analyzed, a considerable percentage of cases meet the definition of HER2-Low. This has relevant therapeutic implications. Distribution of biopsies that meet HER2-Low criteria according to surrogate clinicopathological subtype of breast cancer. [Table: see text]

Benefit of perioperative chemotherapy in the patients with loco-regional recurrence of HR-positive HER2-negative breast cancer: A multi-institutional retrospective cohort study.

526 Background: Loco-regional recurrence (LRR) in breast cancer (BC) is addressed with multimodal treatment, yet the prognosis remains unfavorable. The benefit of adjuvant chemotherapy for the hormone receptor-positive, HER2-negative (HR+HER2-) subtype of BC is controversial. Methods: We performed a multi-institutional retrospective cohort study under the Japan Clinical Oncology Group. This study focused on patients without distant metastasis who developed HR+HER2- ipsilateral breast tumor recurrence (IBTR) or other LRR (oLRR) including recurrence in skin, chest wall, or regional lymph nodes. The patients received curative surgery for LRR between 2014 and 2018. Patients were divided into two groups: the chemotherapy group and no chemotherapy group before/after LRR. We performed a Cox proportional hazards model to evaluate invasive disease-free survival (iDFS) between the two groups. Sensitivity analysis was conducted using propensity score (PS) matching and IPTW. Results: A total of 967 patients were registered from 41 institutions, and 958 patients concordant with inclusion criteria were analyzed. There were 509 patients (53%) of only IBTR and 449 patients (47%) of oLRR. Neoadjuvant/Adjuvant chemotherapy was administered to 235 patients (25%), while 722 (75%) did not receive it. Compared to the no-chemotherapy group, the chemotherapy group included a higher number of patients aged 41-60, oLRR, and recurrences during adjuvant endocrine therapy. At a median follow-up of 5.2 years (Interquartile range: 4.1-6.5), the 5-year iDFS rate was 75.4% (95% CI: 72.4-78.2). Multivariate analysis showed an improvement in iDFS for the chemotherapy group (HR: 0.70, 95% CI: 0.49-0.99, p = 0.045). Sensitivity analysis also consistently suggested the effectiveness of chemotherapy (PS matching HR 0.76, IPTW HR 0.75). In the subgroup analysis, the chemotherapy group showed more significant iDFS improvement in cases with oLRR, recurrences during adjuvant endocrine therapy for primary BC, and those without perioperative chemotherapy for primary BC. Conclusions: Our study showed improvement in iDFS in patients who received perioperative chemotherapy for HR+HER2- LRR. This improvement was particularly notable in patients with oLRR, recurrences during adjuvant endocrine therapy, and those without perioperative chemotherapy for primary BC. [Table: see text]

Abstract PO1-05-12: Pooled clinical trial data analyses comparing the biology of HER2-low vs HER2-0 breast cancer in patients with metastatic breast cancer following treatment with standard single agent chemotherapy

Abstract Background: Prior analyses of observational data suggest that for patients with metastatic breast cancer (MBC), tumor biology does not vary by HER2-low vs. HER2-0 expression given similar overall survival (OS) times after accounting for patients’ clinicopathologic features including hormone receptor (HR) status. We sought to evaluate potential differential biology by HER2-low status by (1) studying data pertaining to patients treated in historic clinical trials (i.e., data collected to measure associations between protocol defined treatments and outcomes) and (2) evaluating the endpoint of progression-free survival (PFS) in addition to OS following treatment with standard single agent chemotherapy for MBC. Methods: Pooling anonymized clinical trial data from studies within the Medidata Enterprise Data Store, we identified 142 women with HER2-negative MBC who received treatment with an NCCN recommended single agent chemotherapy in the context of a clinical trial. Using patient-level immunohistochemistry (IHC) results, we categorized patients as either HER2-low (IHC 1+/2+ and not amplified by in situ hybridization) or HER2-0 (IHC 0). We compared patients’ baseline demographic and clinicopathologic features according to HER2-low vs HER2-0 status. We used Cox proportional-hazard models stratified by HR status to estimate OS and PFS according to HER2-low vs HER2-0 classification while adjusting for patients' baseline demographic and clinicopathologic attributes. Results: Patients with HER2-low disease represented 20% (28/142) of the HER2-negative cohort. Twenty-five percent (7/28) of HER2-low patients had tumors that expressed hormone receptors compared with 17% (19/114) of HER2-0 patients (p=0.31). In this cohort, the maximum follow up time was 38.4 months. For HER2-low patients vs HER2-0 patients, the median OS was 10.7 vs. 12.7 months (p=0.37), and the median PFS was 3.5 vs. 2.9 months (log rank test, p=0.53) respectively. In Cox proportional-hazard models that adjusted for patient demographic and clinicopathologic features and were stratified by HR status, patients with HER2-low tumors had an 16% elevated (non-significant) hazard of death compared with patients with HER2-0 tumors (HR 1.16, 95% CI: 0.69-1.95) and a 22% reduced (non-significant) hazard of progression or death (HR 0.78, 95% CI: 0.45-1.35). Conclusions: Analyses of pooled historic clinical trial data pertaining to women with HER2-negative MBC who were treated with single agent chemotherapy revealed no meaningful clinical differences in either OS or PFS endpoints according to HER2-negative subtypes (i.e., HER2-low vs. HER2-0) after accounting for patient demographic and clinicopathologic features. These results support prior findings from observational research suggesting that there are no biological differences associated with HER2-negative subtypes. Table. Multivariable Cox Proportional Hazards Models for OS and PFS Stratified by Hormone Receptor Status, (N=134) Variable OS PFS HR* 95% CI HR* 95% CI Age (decade) 0.84 0.70-1.01 0.86 0.72-1.01 Race White 1.00 (referent) 1.00 (referent) Black 1.75 0.84-3.63 1.57 0.66-3.73 Asian 0.93 0.47-1.80 1.33 0.71-2.51 Other 1.69 0.45-6.38 2.10 0.62-7.15 Ethnicity Non-Hispanic or Latino 1.00 (referent) 1.00 (referent) Hispanic or Latino 2.10 0.95-4.64 1.02 0.44-2.35 HER2 Characterization HER2-0 1.00 (referent) 1.00 (referent) HER2-1+/2+ 1.16 0.69-1.95 0.78 0.45-1.35 Prior Lines of Chemotherapy for Metastatic Disease 0 1.00 (referent) 1.00 (referent) 1 0.82 0.46-1.46 1.13 0.65-1.95 2 0.69 0.35-1.36 1.00 0.52-1.93 3 0.59 0.10-3.42 2.18 0.45-10.50 ECOG Performance Status 0 1.00 (referent) 1.00 (referent) 1 1.65 1.07-2.54 1.57 1.02-2.43 Legend: OS=overall survival; PFS=progression-free survival; HR=hazard ratio; HER2=human epidermal group factor receptor 2; ECOG=Eastern Cooperative Oncology Group. *Analyses adjusted for clinical trial membership (coefficients not reported) Citation Format: Elizabeth Lamont, Emily Stein, Paolo Tarantino, Sara Tolaney, Corinne Ahlberg, Krishna Chinnathambu, Jiezhi Qi, Kala Tummagunta, Jackie Bilan, Ruthanna Davi, Lisa Ensign. Pooled clinical trial data analyses comparing the biology of HER2-low vs HER2-0 breast cancer in patients with metastatic breast cancer following treatment with standard single agent chemotherapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-05-12.

Abstract PO1-23-08: Exosome-based delivery of microRNAs confers adriamycin-resistance to sensitive cells through modulating the immune and metabolism-related gene PTEN in HER2-negative breast cancer

Abstract Background: Anthracycline-based chemotherapy is widely used to treat breast cancer. However, acquired drug resistance remains a challenge to successful treatment. Recently, increasing evidence has shown that changes in the tumour immune microenvironment (TIME), in addition to increasing drug resistance of tumour cells, consistently contribute to the development of chemoresistance. Methods: TIME scores and tumor-infiltrating immune cells (TICs) scores were used to investigate the prognosis, clinicopathological characteristics and gene transcriptome profiling of HER2-negative breast cancer patients who received anthracycline-based chemotherapy. Exosomes isolated from MCF/7-ADR (ADR-exos) and MCF/7-S (S-exos) cell lines were characterized. We identified dysregulated miRNAs using miRNA microarray analysis on MCF/7-ADR cells and their exosomes compared to MCF/7-S cells and their exosomes. Protein profiling was performed to identify differentially expressed proteins in up- and down-regulated miR-222 cells. The ability of ADR-exos to transfer drug-resistance mediated by miR-222 was assessed by immunofluorescence assay, flow cytometry and qRT-PCR. We optimized the conditions to load miR-222 mimic (or inhibitor) into exosomes produced by HBL-100 cells (H-exos). The influence of miR-222 inhibitor-containing exosomes (inhibitor-exos) on the downstream pathway of miR-222 and the potential therapeutic effects both in vitro and in vivo were evaluated. We also evaluated the relationship between miR-222/PTEN and drug resistance in circulating exosomes from mice after adriamycin-based chemotherapy. Results: Firstly, we discovered the complicated and heterogenous TICs subtypes and their unique biological behaviors in HER2-negative breast cancer. Then, we identified 85 differentially expressed immunologic signature gene sets and 7202 corresponding immune-related genes in three subtypes quantified by gene set variation analysis (GSVA). We identified 12 up-regulated and 13 down-regulated genes using miRNA microarray analysis in adriamycin-resistant cells and their exosomes. The TMT mass spectrometry found 45 differentially expressed proteins affected by the miR-222 level. Moreover, we successfully established miRNA mimic/inhibitor-containing exosomes to explore the solo function of exosomal miR-222 in adriamycin-resistance both in vitro and in vivo. More importantly, for the first time, we detected the levels of miR-222 and its target gene PTEN in circulating exosomes from mice after adriamycin-based chemotherapy and explored the potential clinical implications of miR-222/PTEN-containing exosomes in chemotherapy and immune suppression of breast cancer patients. Conclusions: HER2-negative breast cancer patients own unique TIME subtypes, leading to different outcomes of chemotherapy. We exhibit the potential applications of miR-222-mimic/inhibitor-containing exosomes for reversing chemo-resistance. Adriamycin-resistant cells can transmit drug-resistance to sensitive cells via delivering miR-222 by modulating the immune- and metabolism-related target gene PTEN both in vitro and in vivo without interference from other relevant drug-resistance factors in exosomes. Therefore, miR-222-containing exosomes as well as their target gene PTEN may be a promising biomarker for predicting the efficacy of chemo-resistance and tumor immunity regulation in breast cancer patients receiving anthracycline-based chemotherapy. Keywords: exosomes, breast cancer, tumor immune microenvironment, chemo-resistance, microRNAs Citation Format: Sujin Yang, Tian-cheng Cheng, Jia-hao Wu, Wei-xian Chen. Exosome-based delivery of microRNAs confers adriamycin-resistance to sensitive cells through modulating the immune and metabolism-related gene PTEN in HER2-negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-23-08.

Abstract PO5-02-12: Comparison of survival outcomes according to axillary ultrasonography findings and cytology results in early-stage breast cancer patients

Abstract Purpose: Axillary lymph node dissection and sentinel lymph node biopsy are associated with increased risk of post-surgical complications including lymphedema and recent trials have raised questions about the therapeutic benefit of axillary operation in early-stage breast cancer patients. While treatment options for lymph nodes with negative findings on axillary ultrasonography (AUS) or positive findings on fine needle aspiration biopsy (FNAB) are evident, data regarding lymph nodes that are suspicious on AUS but negative by FNAB are limited. Thus, we aimed to compare clinicopathological characteristics of AUS positive and FNAB negative patients with those of AUS negative or FNAB positive patients. Materials and Methods: Medical records of patients who underwent breast cancer surgery between January 2010 and December 2017 were reviewed. Patients were grouped into the following three groups: (a) negative findings on AUS, (b) suspicious findings on AUS but negative on FNAB, (c) and FNAB positive. A total of 4,506 patients were included for analysis, with 3,771 patients with no suspicious lymph nodes on AUS, 557 patients who had suspicious AUS findings but were negative on FNAB, and 178 patients with positive findings on both AUS and FNAB. Primary endpoints were disease free survival (DFS) and recurrence free survival (RFS), and secondary endpoint was overall survival (OS). Results: At a median follow-up period of 92 months, DFS and RFS was significantly higher in the AUS negative group compared to the other two groups (10-year-DFS: 91.6% vs 87.5% vs 75.7%, 10-year-RFS: 95.0% vs 89.9% vs 77.1%, p &amp;lt; 0.001). In terms of OS, AUS negative group and the AUS positive and FNAB negative group did not show statistically significant survival difference (10-year-OS: 94.5% vs 92.8%, p = 0.061), while the FNAB positive group showed significantly lower survival rates (10-year-OS: 81.8%, p &amp;lt; 0.001). Multivariable analysis revealed that not AUS positive and FANB negative but positive FNAB was significantly associated with poor RFS. Moreover, hormone receptor (HR) positive and HER2 negative subtype showed poor DFS and RFS in subgroup analysis. Conclusion: Early breast cancer patients with suspicious findings on AUS but negative FNAB results had similar OS but inferior DFS and RFS compared to those with negative features on AUS, especially in HR(+)HER2(-) subtype. While further prospective trials are warranted to determine whether additional treatment is necessary, close surveillance is recommended for this subgroup of patients. Figure1. Overall survial and Disease free survival according to axillay US and FNAB status Table1. patients' characteristics Table2. prognostic factors for overall survival and disease free survival related to axillary US and FNAB status Citation Format: Suk Jun Lee. Comparison of survival outcomes according to axillary ultrasonography findings and cytology results in early-stage breast cancer patients [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-02-12.

Salivary Tryptophan as a Metabolic Marker of HER2-Negative Molecular Subtypes of Breast Cancer.

Changes in the concentration of tryptophan (Trp) indicate a serious metabolic restructuring, which is both a cause and a consequence of many diseases. This work examines the upward change in salivary Trp concentrations among patients with breast cancer. This study involved volunteers divided into three groups: breast cancer (n = 104), non-malignant breast pathologies (n = 30) and healthy controls (n = 20). In all participants, before treatment, the quantitative content of Trp in saliva was determined by capillary electrophoresis. In 20 patients with breast cancer, Trp was re-tested four weeks after surgical removal of the tumor. An increase in the Trp content in saliva in breast cancer has been shown, which statistically significantly decreases after surgical removal of the tumor. A direct correlation was found between increased Trp levels with the degree of malignancy and aggressive molecular subtypes of breast cancer, namely triple negative and luminal B-like HER2-negative. These conclusions were based on an increase in Ki-67 and an increase in Trp in HER2-negative and progesterone-negative subtypes. Factors under which an increase in Trp concentration in saliva was observed were identified: advanced stage of breast cancer, the presence of regional metastasis, low tumor differentiation, a lack of expression of HER2, estrogen and progesterone receptors and the high proliferative activity of the tumor. Thus, the determination of salivary Trp may be a valuable tool in the study of metabolic changes associated with cancer, particularly breast cancer.

Tissue Expression of Growth Differentiation Factor 11 in Patients with Breast Cancer.

Protein growth differentiation factor 11 (GDF11) plays crucial roles in cellular processes, including differentiation and development; however, its clinical relevance in breast cancer patients is poorly understood. We enrolled 68 breast cancer patients who underwent surgery at our hospital and assessed the expression of GDF11 in tumorous, ductal carcinoma in situ (DCIS), and non-tumorous tissues using immunohistochemical staining, with interpretation based on histochemical scoring (H-score). Our results indicated higher GDF11 expressions in DCIS and normal tissues compared to tumorous tissues. In addition, the GDF11 H-score was lower in the patients with a tumor size ≥ 2 cm, pathologic T3 + T4 stages, AJCC III-IV stages, Ki67 ≥ 14% status, HER2-negative, and specific molecular tumor subtypes. Notably, the patients with triple-negative breast cancer exhibited a loss of GDF11 expression. Spearman correlation analysis revealed associations between GDF11 expression and various clinicopathological characteristics, including tumor size, stage, Ki67, and molecular subtypes. Furthermore, GDF11 expression was positively correlated with mean corpuscular hemoglobin concentration and negatively correlated with neutrophil count, as well as standard deviation and coefficient of variation of red cell distribution width. These findings suggest that a decreased GDF11 expression may play a role in breast cancer pathogenesis.