Triple-negative Subgroup Research Articles

Survival Outcomes and Prognostic Staging in Locally Advanced Breast Cancer Patients Receiving Radiotherapy: A Single Center Experience

The American Joint Committee on Cancer (AJCC) 8th edition prognostic staging was introduced to improve breast cancer staging by incorporating factors like hormone receptor status and human epidermal growth factor receptor-2 (HER2) expression. This study assesses its effectiveness in locally advanced breast cancer (LABC). A total of 557 patients with locally advanced breast cancer (Stage III) were re-evaluated using prognostic staging. Overall survival (OS), disease-free survival (DFS), and distant metastasis free survival (DMFS) rates were evaluated using the Kaplan-Meier method, and the log-rank test was employed to compare outcomes between anatomic and prognostic staging. According to restaging 34.5% of patients remained in the same stage, while 55.8% were downstaged, and 9.7% were upstaged. When patients reassigned using prognostic staging patients classified as stage IIA showed improved OS rates compared to those in stages IIIA, IIIB, and IIIC (p< 0.001 for each). Patients with prognostic stage IIA had better DFS compared to IIIA, IIIB (p= 0.003, and p< 0.001, respectively). Both anatomic and prognostic staging were found to significantly impact OS in patients with Luminal-A tumors (p= 0.008 and p= 0.001, respectively), whereas neither anatomic nor prognostic stage had any impact on triple negative subgroup. When stage IIIA patients restaged, downstaged individuals showed better OS than those who stayed at the same stage or were upstaged (p= 0.01 and p= 0.02, respectively). This study highlights the prognostic staging system’s superiority over anatomic staging in predicting survival outcomes for LABC, and the use of the prognostic staging system for more personalized treatment strategies. Keywords: Breast cancer, Radiotherapy, Anatomic staging, Prognostic staging

Evaluating interaction between tumor educated platelets and cancer stem cells on breast cancer subtypes.

5 Background: Thrombocytosis has been reported to be responsible for poor prognosis of numerous malignancies. This swarm of platelets acts as foe for the body but as mate for the cancer cells by providing a protective shield around them, helping them to escape immunosurveillance process. A bidirectional interaction between platelets and tumor cells promote their conversion to an activated tumor educated platelet (TEP) state. The present report reveals the critical role played by TEPs to promote metastasis in BC subtypes by interacting with cancer stem cells (CSCs). Methods: Status of intra-tumoral and humoral TEPs (CD41+/CD62P+) was screened in luminal A (LumA) and triple negative (TNBC) BC subgroups. The impact of TEPs on lin-/CD44+/CD24- CSCs of both the categories in-vitro, was deciphered by performing mammosphere assay, clonogeneic and migration assays, with final validation in murine system. Effect on various genes and proteins related to stemness, metastasis and angiogenesis as a result of this interaction was elucidated by RT-PCR, flow cytometry and western blotting. Results: High percentage of TEPs in the peripheral blood is a potential biomarker and responsible for poor prognosis in BC subtypes. Both Lum A and TNBC patients had elevated TEP frequency, compared to healthy blood. Further, patients in the pre-carcinogenic stage had platelet count of >3.5 lakhs. Additionally, screening of breast tumor sections revealed intra-tumoral enrichment of TEPs, comparatively to a greater extent in TNBC than LumA, supporting their role in disease aggression. Also, a positive correlation was noted between TEP and CSC frequencies proving their synergistic interactions. Moreover, in-vitro, TEP influenced CSCs exhibited enormous clonogenic and tumorigenic potentialities. Their metastatic nature was confirmed by their enhanced migratory, invasive, angiogenic capacities with higher VIMENTIN and TWIST along with HIF1α, CD31 and MMP9 expression compared to E-CADHERIN. In line with in-vitro observations, in-vivo too, TEP~CSC produced metastatic colonies in murine lungs. Upon investigation, it was disclosed that it is through WNT-βcatenin-VEGFR2 axis that this mutual interdependency was functioning. Conclusions: This study advocates for the importance of TEPs as potential biomarker in BC diagnosis. Their alliance with vicious CSCs to promote disease advancement acquiesce them as a novel restorative agent.

Prediction of the number of positive axillary lymph nodes according to sentinel lymph node involvement and biological subtypes in patients receiving neoadjuvant chemotherapy

BackgroundSentinel lymph node biopsy (SLNB) has replaced axillary lymph node dissection (ALND) for assessing axillary lymph node status in clinically node-negative breast cancer patients. However, the approach to axillary surgery after neoadjuvant treatment is still controversial. In the present study, our objective was to predict the pathological nodal stage based on SLNB results and the clinicopathological characteristics of patients who initially presented with clinical N1 positivity but whose disease status was converted to clinical N0 after neoadjuvant chemotherapy (NAC).Materials and methodsAfter NAC, 150 clinically node-negative patients were included. The relationships between clinicopathologic parameters and the number of positive lymph nodes in SLNBs and ALNDs were assessed through binary/multivariate logistic regression analysis.ResultsAmong 150 patients, 78 patients had negative SLNBs, and 72 patients had positive SLNBs. According to the ALND data of 21 patients with SLNB1+, there was no additional node involvement (80.8%), 1–2 lymph nodes were positive in 5 patients (19.2%), and no patient had ≥ 3 lymph nodes involved. Following the detection of SLNB1 + positivity, the rate of negative non-sentinel nodes were 75% in the luminal A/B subgroup, 100% in the HER-2-positive subgroup, and 100% in the triple-negative subgroup. Patients with a lower T stage (T1-3 vs. T4), fewer than 4 clinical nodes before NAC (< 4 vs. ≥4), and a decreased postoperative Ki-67 index (< 10% vs. stable/increase) were included. According to both univariate and multivariate analyses, being in the triple-negative or HER2-positive subgroup, compared to the luminal A/B subgroup (luminal A/B vs. HER2-positive/triple-negative), was found to be predictive of complete lymph node response.ConclusionThe number of SLNB-positive nodes, tumor-related parameters, and response to treatment may predict no additional nodes to be positive at ALND.

Genomic biomarkers of CNS-specific outcomes in patients with breast cancer brain metastases.

2028 Background: The diagnosis of brain metastasis (BM) is a life- and prognosis-altering event for patients with breast cancer (BC). The standard of care for the management of limited BM remains ablation with stereotactic radiosurgery (SRS). There are no established genomic biomarkers to guide CNS-directed treatment among patients with breast cancer brain metastases (BCBM). Methods: We retrospectively reviewed clinical and genomic features of a cohort of patients who received SRS for newly diagnosed BCBM between 2010 and 2021 at Memorial Sloan Kettering Cancer Center (MSK). Next-generation genomic sequencing (NGS) was performed using the MSK-IMPACT assay, covering all exonic and selected intronic regions for up to 505 genes. Time-to-CNS progression (TTCP) and overall survival (OS) were analyzed using multivariable Fine-Gray and Cox proportional hazards models, respectively, adjusted for clinically relevant factors. Relevant clinical factors and genomic alterations present at an instance at 5% or greater were included in the univariate and multivariate analyses, completed for the overall cohort and BC receptor subtypes. Results: From 2010-2021, 260 patients were identified; 123 (47%), 74 (28%), and 63 (24%) patients had hormone receptor-positive (HR+), HER2+, and triple-negative (TN) disease, respectively. 116 (45%) patients had 1 BM and 184 (71%) patients had at least 1 BM greater than 1 cm in axial diameter. Median follow up for the overall cohort was 18 months (Interquartile range (IQR) 9, 36). Among patients who progressed, median TTCP was 6 (IQR 4, 13) and 6 (4, 13), 11 (5, 18), and 4(3, 8) months for the overall cohort, and HR+, HER2+, and TN subgroups, respectively. Median OS was 19 (95% CI 16, 23) and 15 (13, 21), 58 (39, --), and 13 (11, 20), for the overall cohort, and HR+, HER2+, and TN subgroups, respectively. In the overall cohort, shorter TTCP was associated with TN subtype, &gt;5 BMs, and pathogenic alterations in MYC, AGO2, PTEN, AURKA, and NF1 (p &lt; 0.05); decreased OS was associated with non-HER2+ subtype, presence of extracranial metastatic disease, and oncogenic alterations in TP53, CDH1 and NF1 (p &lt; 0.05). In stratified analyses by receptor subtype, shorter TTCP was associated with oncogenic alterations in GAB2 and PTEN in the HR+ subgroup, AURKA, DDR2, and NF1 in the HER2+ subgroup, and with MYC and RB1 in the TN subgroup (p &lt; 0.05). Conclusions: In this large clinico-genomic analysis of CNS-specific outcomes in BC, we identified clinical and putative genomic biomarkers associated with BCBM receiving SRS that could be used to risk stratify patients and optimize treatment strategies.

Efficacy and safety of eribulin plus gemcitabine in second-line or beyond for patients with HER2-negative metastatic breast cancer (MBC): A multicenter, open-label, single-arm, phase II study.

e13139 Background: The combination of eribulin and gemcitabine has demonstrated a similar progression-free survival (PFS) benefit as paclitaxel plus gemcitabine, with less neurotoxicity, for patients with MBC who have not received prior cytotoxic chemotherapy. However, the effect of eribulin plus gemcitabine on PFS in second line or beyond remains unclear. Methods: This open-label, single-arm, phase II study (NCT05263882) was conducted at 14 institutions in China. Eligible patients had histologically confirmed HER2-negative MBC and had received at least one prior taxane-containing chemotherapy regimen for advanced disease, and anthracycline-containing regimens in the adjuvant setting. Patients received intravenous infusions of eribulin (1.4 mg/m2) and gemcitabine (1.0 g/m2) on days 1 and 8 of a 21-day cycle. Efficacy outcomes, including PFS, objective response rate (ORR), and disease control rate (DCR), were assessed using RECIST v1.1. Adverse events (AEs) were graded according to NCI-CTC version 5.0. Results: A total of 70 patients were enrolled from November 2021 to October 2023; 47 (71.4%) had HR+HER2- and 18 (28.6%) had triple-negative MBC. The median patient age was 50 years (range: 31-68), and the sites of metastasis were the bone (68.6%), liver (52.9%), lymph nodes (48.6%), lung (44.3%) and brain (10.0%). Patients had received a median of 3 prior lines of systemic treatment, 2 lines of chemotherapy, and 1 line of endocrine treatment. Among all patients, the ORR was 48.6%, the DCR was 92.9% and the median PFS was 7.2 months. For the HR-positive subgroup, the median PFS was 8.4 months, while for the triple-negative subgroup, it was 6.3 months. Among HR+ patients who had received prior CDK4/6 inhibitor treatment, the median PFS was 7.2 months. In the subgroup of HR+ patients who had not received CDK4/6 inhibitor treatment, the median PFS had not been reached. For the HR+ HER2-low subgroup, the median PFS was 8.4 months. The most common grade 3-4 AEs were hematological, including neutropenia (38.6%), leukopenia (31.4%), anemia (24.3%), and thrombocytopenia (15.7%). Grade ≥3 perceived AEs were relatively low. Conclusions: Eribulin plus gemcitabine was effective in heavily pretreated patients with HER2- MBC, while maintaining a predictable and manageable safety profile. Clinical trial information: NCT05263882 . [Table: see text]

Characterization of HER2-low breast cancer in young women with germline BRCA1/2 pathogenetic variants: Results of a large international retrospective cohort study.

Breast cancer (BC) in women aged ≤40 years carrying germline pathogenetic variants (PVs) in BRCA1/2 genes is infrequent but often associated with aggressive features. Human epidermal growth factor receptor 2 (HER2)-low-expressing BC has recently emerged as a novel therapeutic target but has not been characterized in this rare patient subset. Women aged ≤40 years with newly diagnosed early-stage HER2-negative BC (HER2-0 and HER2-low) and germline BRCA1/2 PVs from 78 health care centers worldwide were retrospectively included. Chi-square test and Student t-test were used to describe variable distribution between HER2-0 and HER2-low. Associations with HER2-low status were assessed with logistic regression. Kaplan-Meier method and Cox regression analysis were used to assess disease-free survival (DFS) and overall survival. Statistical significance was considered for p≤.05. Of 3547 included patients, 32.3% had HER2-low BC, representing 46.3% of hormone receptor-positive and 21.3% of triple-negative (TN) tumors. HER2-low vs. HER2-0 BC were more often of grade 1/2 (p<.001), hormone receptor-positive (p<.001), and node-positive (p=.003). BRCA2 PVs were more often associated with HER2-low than BRCA1 PVs (p<.001). HER2-low versus HER2-0 showed better DFS (hazard ratio [HR], 0.86; 95% CI, 0.76-0.97) in the overall population and more favorable DFS (HR, 0.78; 95% CI, 0.64-0.95) and overall survival (HR, 0.65; 95% CI, 0.46-0.93) in the TN subgroup. Luminal A-like tumors in HER2-low (p=.014) and TN and luminal A-like in HER2-0 (p=.019) showed the worst DFS. In young patients with HER2-negative BC and germline BRCA1/2 PVs, HER2-low disease was less frequent than expected and more frequently linked to BRCA2 PVs and associated with luminal-like disease. HER2-low status was associated with a modestly improved prognosis.

Abstract PO3-05-10: Efficacy and safety of eribulin plus gemcitabine in second-line or beyond for patients with HER2-negative metastatic breast cancer (MBC): A multi-center, open-label, single-arm, phase II study

Abstract Background: Eribulin is a halichondrin non-taxane inhibitor of microtubule dynamics approved in China for advanced breast cancer patients who have received at least two prior chemotherapy treatments. The combination of eribulin and gemcitabine has demonstrated a similar progression-free survival (PFS) benefit as paclitaxel plus gemcitabine, with less neurotoxicity, for patients with MBC who have not received prior cytotoxic chemotherapy. However, the effect of eribulin plus gemcitabine on PFS in second line or beyond remains unclear. Methods: This open-label, single-arm, phase II study (NCT05263882) was conducted at 13 institutions in China. Eligible patients had histologically confirmed HER2-negative MBC and had received at least one prior taxane-containing chemotherapy regimen for advanced disease, and anthracycline-containing regimens in the adjuvant setting. Patients received intravenous infusions of eribulin (1.4 mg/m2) and gemcitabine (1.0 g/m2) on days 1 and 8 of a 21-day cycle. Efficacy outcomes, including PFS, objective response rate (ORR), and disease control rate (DCR), were assessed using RECIST v1.1. Adverse events (AEs) were graded according to NCI-CTC version 5.0. Results: A total of 65 patients were enrolled from November 2021 to May 2023; 47 (72.3%) had HR+/HER2- and 18 (27.7%) had triple-negative MBC. The median patient age was 50 years (range: 31-68), and the sites of metastasis were the bone (70.8%), liver (58.5%), lymph nodes (50.8%), lung (43.1%) and brain (10.8%). Patients had received a median of 3 prior lines of systemic treatment, 2 lines of chemotherapy, and 1 line of endocrine treatment. Among all patients, the ORR was 52.3%, the DCR was 92.3% and the median PFS was 7.6 months (Table). For the HR-positive subgroup, the median PFS was 8.4 months, while for the triple-negative subgroup, it was 7.6 months. Among patients who had received prior CDK4/6 inhibitor treatment, the median PFS was 7.2 months. In the subgroup of patients who had not received CDK4/6 inhibitor treatment, the median PFS had not been reached. The most common grade 3-4 AEs were hematological, including neutropenia (41.6%), leukopenia (33.9%), anemia (23.1%), and thrombocytopenia (15.4%). No grade ≥3 perceived AEs were reported. Conclusion: Eribulin plus gemcitabine was effective in heavily pretreated patients with HER2- MBC, while maintaining a predictable and manageable safety profile. Table. Summary of efficacy outcomes Citation Format: PeiJian Peng, Xiao-Lu Xu, Jin-Cai Zhong, Jin-Hui Ye, Zhi-Hui Wang, Hong Wang, Hong Lin, Cai-Wen Du, Guorong Zou, Jie Ouyang, Ying-Ying Shi, Fei Xu, Geng-Sheng Yu, Yong-Kui Lu, Yong-Xia Wang, Shi-En Cui, Lu-Zhen Li. Efficacy and safety of eribulin plus gemcitabine in second-line or beyond for patients with HER2-negative metastatic breast cancer (MBC): A multi-center, open-label, single-arm, phase II study [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 PO3-05-10.

Clinico–pathologic factors and survival of patients with breast cancer diagnosed with de novo brain metastasis: a national cancer database analysis

PurposePatients with Breast Cancer (BC) with Brain Metastasis (BCBM) have poor survival outcomes. We aimed to explore the clinico–pathologic and therapeutic factors predicting the survival in patients with de novo BCBM using the National Cancer Database (NCDB).Patients and methodsThe NCDB was queried for patients with BC between 2010 and 2020. Survival analysis with Kaplan–Meier curves and log rank tests were used to find median overall survival (OS) in months (95% CI) across the different variables. A multivariate cox regression model was computed to identify significant predictors of survival.ResultsOut of n = 2,610,598 patients, n = 9005 (0.34%) had de novo BCBM. A trend of decreasing OS was observed with increasing age, Charlson–Deyo score (CDS), and number of extracranial metastatic sites. The highest median OS was observed in the Triple Positive and the lowest OS in the Triple Negative subgroup. Based on treatment regimen, combination of systemic therapy and local therapy achieved the highest OS. A positive trend in OS was observed in the BC subgroup analysis with targeted therapy demonstrating a survival benefit when added to systemic therapy.The multivariate cox regression model showed that age, race, ethnicity, insurance, median income, facility type, CDS, BC subtype, metastatic location sites, and treatment combinations received were significantly associated with risk of death. Receiving only local treatment for BM without systemic therapy more than doubled the risk of death compared to combining it with systemic therapy.ConclusionsThis analysis suggests that treatment of systemic disease is the major factor influencing survival in patients with BCBM. Moreover, targeted therapy with anti–HER2 increased survival when added to systemic therapy explaining the highest median OS noted in the Triple Positive subgroup.

Investigation of the Relationship Between Tumor Microenvironment and Prognostic Parameters in Invasive Breast Carcinomas of No Special Type: A Retrospective Analysis.

The tumor microenvironment is a heterogeneous and constantly changing territory that plays an active role in tumor formation and progression. It constantly interacts with tumor cells, plays an active role in tumor development, and even appears as a parameter of prognostic importance, and the importance of the tumor microenvironment in breast cancer has been emphasized by recent studies. In this study, we aimed to retrospectively evaluate the relationship between the tumor microenvironment and prognostic parameters in invasive breast carcinomas of no special type. A total of 271 cases diagnosed as invasive breast carcinoma of no special type from resection materials in our center between 2007 and 2015 were included in the study. Hematoxylin-eosin stained slides with a thickness of 4-5 micrometers were evaluated in terms of tumor infiltrating lymphocytes, peritumoral and intratumoral desmoplastic reaction, intratumoral and peritumoral tumor budding, stromal features, and tumor growth pattern. When parameters related to the tumor microenvironment were compared with other prognostic parameters, there was a significant relationship between TILs and tumor grade, size, stage, immunohistochemical subgroup and Ki-67 proliferation index. A significant relationship was detected between intratumoral stromal reaction and tumor grade, size, molecular subgroup and the Ki-67 proliferation index (p < 0.05). When stroma and other prognostic parameters were compared, tumors with desmoplastic stroma had higher grades and higher Ki-67 proliferation indexes, and they were observed more frequently in the triple negative molecular subgroup. We believe that including parameters related to tumor microenvironment in breast cancer reports, which hold a prognostic and predictive importance, will contribute to patient management. Considering the fact that these can be easily evaluated from routinely used hematoxylin-eosin stained slides, this does not cause additional costs or excessive time loss.

Neoadjuvant Systemic Therapy in Early Breast Cancer: Results of a Prospective Observational Multicenter BRIDE Study.

To evaluate the rate of early breast cancer (EBC) patients treated with neoadjuvant systemic therapy (NAT) in Italy, criteria of patient selection and types of therapies delivered, an analysis of 1276 patients with stage I-II-III was conducted out of 1633 patients enrolled in the multicenter prospective observational BRIDE study. A total of 177 patients (13.9%) were treated with NAT and 1099 (85.9%) with surgery; in multivariate analysis, menopausal status, cT, cN, grade, HER2-positive and Triple negative (TN) subgroups were significantly associated with the decision to administer NAT. The type of NAT delivered was influenced by EBC subtype. NAT was administered to 53.2% of HER2+/HR-negative, 27.9% of HER2+/HR+, 7.1% of HER2-negative/HR+ and 30.3% of TN EBC patients. The pCR rates were similar to the ones reported in the literature: 74.2% in HER2+/HR-negative, 52.3% in HER2+/HR+, 17.2% in HER2-negative/HR+ and 37.9% in TN. In clinical practice, patient and tumor characteristics influenced oncologists in the decision to administer NAT in EBC and in the choice of the type of systemic therapy, according to ESMO and AIOM Guidelines. Currently, it is recommended always to evaluate the use of NAT in EBC, mainly in HER2+ and TN patients, considering that pCR is associated with significantly better survival of the patient and that effective therapies are now available for residual disease.

Characterization of clinicopathological features, treatment practices, and outcomes among Finnish advanced breast cancer patients in real-life clinical practice.

In recent years, several new targeted therapies have emerged for advanced breast cancer (aBC). However, real-life data specific to aBC and different breast cancer subtypes are scarce. This retrospective cohort study was designed to describe the distribution of aBC subtypes, incidence, treatment patterns, survival, and PIK3CA hotspot mutation frequency. The study included all patients in the Hospital District of Southwest Finland diagnosed with aBC between 2004 and 2013 and with a sample available in Auria Biobank. In addition to registry-based data collection, 161 HR+/HER2- aBCs were screened for PIK3CA mutations. Altogether, 54.7% of the 444 patients included in the study had luminal B subtype. The smallest representations were in HR-/HER2+ (4.5%) and triple-negative (5.6%) subgroups. The percentage of aBC among all diagnosed breast cancers increased until 2010, after which it remained stable. The triple-negative cancers were associated with shorter median overall survival (5.5months) compared to other subgroups (16.5-24.6months). Most (84%) triple-negative cancers also metastasized during the first two years, whereas this was more evenly distributed over time in other subgroups. Of the HR+/HER2- tumors, 32.3% harbored a PIK3CA hotspot mutation. These patients, however, did not have inferior survival compared to patients with PIK3CA wild-type cancers. This study described real-world aBC subgroups and indicated that the clinical outcomes of subgroups vary. Although PIK3CA hotspot mutations did not lead to inferior survival, they are relevant as possible treatment targets. Overall, these data could be utilized to further evaluate the subgroup-specific medical needs in breast cancer.

Machine learning analysis of breast ultrasound to classify triple negative and HER2+ breast cancer subtypes.

Early diagnosis of triple-negative (TN) and human epidermal growth factor receptor2 positive (HER2+) breast cancer is important due to its increased risk of micrometastatic spread necessitating early treatment and for guiding targeted therapies. This study aimed to evaluate the diagnostic performance of machine learning (ML) classification of newly diagnosed breast masses into TN versus non-TN (NTN) and HER2+ versus HER2 negative (HER2-) breast cancer, using radiomic features extracted from grayscale ultrasound (US) b-mode images. A retrospective chart review identified 88 female patients who underwent diagnostic breast US imaging, had confirmation of invasive malignancy on pathology and receptor status determined on immunohistochemistry available. The patients were classified as TN, NTN, HER2+ or HER2- for ground-truth labelling. For image analysis, breast masses were manually segmented by a breast radiologist. Radiomic features were extracted per image and used for predictive modelling. Supervised ML classifiers included: logistic regression, k-nearest neighbour, and Naïve Bayes. Classification performance measures were calculated on an independent (unseen) test set. The area under the receiver operating characteristic curve (AUC), sensitivity (%), and specificity (%) were reported for each classifier. The logistic regression classifier demonstrated the highest AUC: 0.824 (sensitivity: 81.8%, specificity: 74.2%) for the TN sub-group and 0.778 (sensitivity: 71.4%, specificity: 71.6%) for the HER2 sub-group. ML classifiers demonstrate high diagnostic accuracy in classifying TN versus NTN and HER2+ versus HER2- breast cancers using US images. Identification of more aggressive breast cancer subtypes early in the diagnostic process could help achieve better prognoses by prioritizing clinical referral and prompting adequate early treatment.

Abstract P5-02-43: Incidence of HER2-low Expression in HR-positive/HER2-negative and Triple-Negative Breast Cancers in the Integra Connect Database

Abstract Approximately half of primary breast cancers exhibit low levels of human epidermal growth factor receptor 2 (HER2), defined as a score of 1+ on immunohistochemical (IHC) analysis or a score of 2+ on IHC and lack of HER2 gene amplification on in situ hybridization (ISH). Tumors classified as HER2-low represent a target for novel antibody-drug conjugates. In addition, HER2-low expression accounts for about 60% of HER2-negative breast cancers (BC). Real-world studies noted that HER2-low represents 47-54% of hormone positive (HR-positive)/HER2-negative breast cancers, a percentage higher than in the triple negative subgroup, reported at 35%. The goal of this study was to determine the frequency of HER2-low expression in patients with HR-positive/HER2-negative and triple-negative breast cancers (TNBCs) in the real-world and compare it with the published literature. The IntegraConnect (IC) real-world database of 330 thousand breast cancer patients was used for this analysis. Within the IC database, a subgroup of 387 patients with HR-positive/HER2-negative breast cancer and 618 patients with TNBC were abstracted with medical chart curation. The mean age at diagnosis for each group was 56 years and most patients had an ECOG performance status of 0-1. The statistical tests used were the Mann-Whitney test for age at diagnosis and the Chi-squared test for race, major stage, and ECOG at diagnosis. Differences were considered significant at P &amp;lt; .05. In the HR-positive/HER2-negative subgroup (n=387), 327 patients were tested by IHC and ISH. Sixty patients were tested by ISH only and were removed as they did not fit the definition of HER2-low. Of the 327 HER2-negative patients, 199 patients exhibited low HER2 expression (IHC1+, n=138 patients; IHC2+/ISH-negative, n=61), accounting for 61% (199/327) of HR-positive/HER2-negative breast cancers. In this group, numerically more patients were HER2-low than HER2-negative across all race subgroups. In the TNBC patient group (n=618), 546 patients tested HER2-negative by ICH and ISH. Patients testing HER2-negative by ISH only were removed (n=72) from the analysis. Of 546 patients with TNBC, HER2-low expression accounted for 42% (227/546) [IHC1+, n=168; IHC2+/ISH-negative, n=59]. In the Black or AA patients with TNBC subgroup, 37.2% (N=129) were HER2-low compared with 44% (N=353) in White patients. In all TNBC race subgroups, numerically more patients were HER2-negative compared with HER2-low. In addition, the proportion of HER2-low expression was higher in the HR+/HER2-negative subgroup (N=327) than in TNBC (N=546) (61% vs 42%, respectively), corroborating literature reports. In conclusion, analysis of the IC database showed HER2-low expression in 61% of HR-positive/HER2-negative breast cancers and in 42% of TNBC patients. Approximately 37% of Black or African Americans (AA) patients with TNBC expressed low levels of HER2. The frequency of HER2-low expression in TNBC in the IC database at 42% is slightly higher than previous studies that estimate HER2-low expression at 35% of TNBC. The percentage of HER2-low in HR+/HER2-negative breast cancers at 61% is higher than previous reports, which estimate low HER2 expression in patients with primary and recurrent HR+/HER2-negative breast cancers at 47 and 54%, respectively. Citation Format: Marielle Fares, Mike Gart, Simon Blanc, Jia Zheng, William Saunders, Robert Smith, Anupama Vasudevan, Sandy English. Incidence of HER2-low Expression in HR-positive/HER2-negative and Triple-Negative Breast Cancers in the Integra Connect Database [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-43.

Abstract P6-01-33: Diffusion-weighted magnetic resonance imaging for subtype-specific prediction of pathologic complete response in neoadjuvant chemotherapy

Abstract Background: The apparent diffusion coefficient (ADC) presents a biomarker that is sensitive to tumor cellularity. ADC maps can be calculated from non-contrast diffusion-weighted magnetic resonance imaging (DW-MRI) measurements. ACRIN 6698, a sub-study of clinical trial I-SPY 2, investigated mean ADC – averaged over the whole tumor – as a marker to predict pathologic complete response (pCR) [1]. This work compares a group of histogram-based ADC metrics in addition to mean ADC for early prediction of pCR in patients stratified by breast cancer subtype. Methods: We performed a retrospective analysis of DW-MRI, dynamic-contrast enhanced (DCE) MRI, and clinical outcome (i.e., pCR at surgery) in a cohort of 79 female patients who were diagnosed with high-risk, stage II/III breast cancer. Patients underwent neoadjuvant chemotherapy (NAC) with paclitaxel (12 weeks), followed by doxorubicin plus cyclophosphamide (12 weeks). The included population represents a subset of the I-SPY 2 cohort and comprises 48 patients with hormone receptor [HR]+/HER2-, and 31 patients with HR-/HER2-. DW- and DCE-MRI acquisitions were performed according to the I-SPY 2 protocol at pretreatment (T0) and after three weeks (T1) and were analyzed to find early treatment percentage (%) change (T0 to T1) in any metric M; where %-change = 100 × (M(T1) – M(T0))/M(T0). Histogram analysis provided nine region-of-interest (ROI)-based ADC metrics (Table 1). ROIs were manually delineated by expert observers in three-dimensional ADC maps, focusing on diffusion-restricted regions [2]. DCE-MRI was analyzed for the integral I-SPY 2 imaging marker of %-change in functional tumor volume (FTV) between T0 and T1. Statistical analysis compared the predictive power of ADC metrics and FTV, including: the receiver-operating-characteristic (ROC) curve from a logistic regression model to predict pCR as ‘positive’, area-under-the-curve (AUC) assessment, and rank-sum Wilcoxon test (p&amp;lt; 0.05: statistically significant). Results (Table 1): 16 out of 79 (20.3%) patients reached pCR at surgery, with 18.8% pCR among HR+/HER- and 22.6% among HR-/HER2- groups. For all nine computed ADC statistics (listed as median [Q1, Q3], across all patients), %-change was higher in patients who reached pCR than patients with non-pCR (highest value for metric ‘MIN’: 23.9% [-0.9%, 52.5] vs. 16.6% [0.4%, 27.6%], though without statistical significance: p=0.237). Likewise, %-change of FTV was also stronger in pCR patients than non-pCR patients (-58.8% [-80.6%, -22.5%] vs. -28.2% [54.2%, -2.7%], with statistical significance: p=0.036). For all patients combined (n=79), among the various reported ADC metrics, %-change in ‘PCTL_95’ (95th percentile of histogram) yielded the highest AUC (0.7; 95% CI = [0.56, 0.83]; p=0.012). %-change in FTV showed the second highest AUC (0.67; 95% CI = [0.52, 0.82]; p=0.036). By subtype, AUC was highest for %-change of ‘PCTL_95’ (0.69; 95% CI = [0.5, 0.87]; p=0.072) in the HR+/HER2- subgroup; and highest for both %-change of ‘MEAN’ (AUC = 0.73; 95% CI = [0.49, 0.94]; p=0.065) and ‘PCTL_75’ (AUC = 0.73; 95% CI = [0.49, 0.94]; p=0.073) triple negative (HR-/HER2-) subgroup. By comparison, %-change of FTV yielded AUCs of 0.64 (95% CI = [0.41, 0.85]; p=0.191) and 0.71 (95% CI = [0.51, 0.9]; p=0.098) in the HR+/HER2- and triple-negative subgroups, respectively. Conclusion: Various tumor ADC metrics from non-contrast DW-MRI demonstrate potential biomarkers for assessing responsiveness to NAC at an early treatment timepoint. ADC may have predictive performance that is comparable to FTV, depending on the breast cancer subtype. Observations for %-change in ‘MEAN’ ADC at T1 differed from previous reports [1], which may be explained by the small sample size and single (paclitaxel) drug arm. Additional studies are warranted to include patients of experimental arms and of HER2+ subtypes. [1] Partridge et al., Radiology 289(3):618-27 (2018) [2] Nu et al., Tomography 8: 1208-20 (2022) Results of statistical analysis of ADC-based and FTV markers for predicting treatment response at 3 weeks into NAC. Median [Q1, Q3] values represent the median and interquartile range over the respective patient population regarding the %-change of the respective ADC (FTV) metric from T0 to T1. T0: pretreatment, T1: 3-week timepoint, ADC: apparent diffusion coefficient, MRI: magnetic resonance imaging, DW: diffusion-weighted, DCE: dynamic-contrast enhanced, pCR: pathologic complete response, AUC: area under the ROC curve, 95% CI [LL, UL]: confidence interval lower and upper limit, PCTL_x: xth-percentile of tumor ADC histogram, MEAN: mean of ADC within ROI, MIN: minimum of ADC within ROI, MAX: maximum of ADC within ROI, FTV: functional tumor volume, **: statistically significant. Citation Format: Judith Zimmermann, Julia Carmona-Bozo, Nu N. Le, Natsuko Onishi, Lisa J. Wilmes, Jessica E. Gibbs, Jiachao Liang, David C. Newitt, Savannah Partridge, Patrick Bolan, Bonnie N. Joe, Elissa R. Price, Barbara LeStage, Nola M. Hylton, Wen Li. Diffusion-weighted magnetic resonance imaging for subtype-specific prediction of pathologic complete response in neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-33.

Abstract P2-26-06: Association between CK+/CD45+ circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) alterations in advanced breast cancer patients

Abstract Background: Circulating tumor cells (CTCs) in breast cancer (BC) are commonly defined as epithelial cells (EPCAM and cytokeratin (CK) positive), lacking the universal blood cell marker CD45. Nonetheless, CTCs expressing both CK and CD45 (= dual-positive, DP cells) can be observed in the blood of cancer patients. Early evidence suggests that DP cells might derive from the fusion of tumor cells and macrophages, and we have previously demonstrated that they present aberrant genomes and are associated with worse prognosis in BC [1,2]. Here, to further investigate the mechanisms/pathways underlying their presence, we analyzed the association between DP cells and circulating tumor DNA (ctDNA) alterations. Methods: Blood samples were collected from patients with advanced BC (aBC), before starting a new line of therapy. All patients were enrolled in a prospective clinical trial. For CTC and DP cells analysis, 7.5 ml of blood collected in CellSave® tubes was processed with the FDA-approved CellSearch® platform (positivity cutoffs were ≥1 cell for DPcells and ≥5 cells for CTCs). For ctDNA analysis, plasma was collected from Streck stabilizing tubes and analyzed with the Guardant360™ NGS platform for the detection of somatic single nucleotide variants (SNVs), insertions/deletions (indels), gene fusions/rearrangements and copy number variations (CNVs), which were then classified into pathways based on previously defined profiles generated on the Cancer Genome Atlas database (RTK, RAS, RAF, MEK, NRF2, ER, WNT, MYC, P53, cell cycle, notch, PI3K). Associations between ctDNA-detected gene alterations and circulating cell types were analyzed through chi square test, while mutant allele frequency (MAF) and number of detected alterations (NDA) were tested by Mann Whitney test. Results: We analyzed blood samples from 169 patients with luminal-like (n=80), HER2+ (n=34) and triple-negative (n=52) aBC. DPcells were detected in 85 patients (50.3 %, range 0-53), of which 40 (47 %) were CTC-positive and 45 (53%) CTC-negative. Somatic ctDNA alterations were detected in all analyzed samples. In the overall population, the presence of ≥1 DPcell was associated with SNVs in the cell cycle pathway (p = 0.043), a numerically higher incidence was also observed for CNVs in this pathway. SNVs and CNVs in the cell cycle pathway were associated with CTCs ≥ 5 as well (p = 0.005 and p = 0.003, respectively). Moreover, associations with CTCs ≥ 5 were observed for RTK SNVs and CNVs (p = 0.041 and p = 0.046, respectively), PI3K SNVs and CNVs (p = 0.006 and p = 0.007, respectively), MYC SNVs and CNVs (p = 0.042). No associations were observed in terms of MAF and NDA. In the luminal-like subgroup an association was highlighted for CNVs in the cell cycle pathway, p = 0.038. CTCs ≥ 5 were associated with PI3K SNVs (p = 0.031). In the triple-negative subgroup DPcells were associated with SNVs in the RAF pathway (p = 0.041), whereas CTCs ≥ 5 were associated with PI3K SNVs and CNVs (p = 0.044 and p = 0.024, respectively) and RTK SNVs (p = 0.008). In the HER2 positive subgroup, a higher MAF and number of detected SNVs was observed for samples with ≥1 DPcell (p = 0.0286 and p = 0.0099, respectively). Conclusions: The study analyzed ctDNA features associated with canonical and CK+/CD45+ CTCs, showing differential gene alteration profiles. Cell cycle pathway SNVs were common in both CTC populations, while other pathways (RTK, PI3K, MYC and RAF) were significantly altered in a mutually exclusive pattern. These results suggest that DPcells might have a different biological meaning compared to canonical CTCs. More studies need to be conducted to better characterize this understudied CTC subpopulation and understand their specific contribution to cancer progression.

Prognostic effect of HER2 evolution from primary breast cancer to breast cancer metastases

PurposeTherapeutic options for breast cancer (BC) treatment are constantly evolving. The Human Epidermal Growth Factor 2 (HER2)-low BC entity is a new subgroup, representing about 55% of all BC patients. New antibody–drug conjugates demonstrated promising results for this BC subgroup. Currently, there is limited information about the conversion of HER2 subtypes between primary tumor and recurrent disease.MethodsThis retrospective study included women with BC at the University Medical Centre Wuerzburg from 1998 to 2021. Data were retrieved from patients' records. HER2 evolution from primary diagnosis to the first relapse and the development of secondary metastases was investigated.ResultsIn the HR-positive subgroup without HER2 overexpression, HER2-low expression in primary BC was 56.7 vs. 14.6% in the triple-negative subgroup (p < 0.000). In the cohort of the first relapse, HER2-low represented 64.1% of HR-positive vs. 48.2% of the triple-negative cohort (p = 0.03). In patients with secondary metastases, HER2-low was 75.6% vs. 50% in the triple negative subgroup (p = 0.10). The subgroup of HER2-positive breast cancer patients numerically increased in the course of disease; the HER2-negative overall cohort decreased. A loss of HER2 expression from primary BC to the first relapse correlated with a better OS (p = 0.018). No clinicopathological or therapeutic features could be identified as potential risk factors for HER2 conversion.ConclusionHER2 expression is rising during the progression of BC disease. In view of upcoming therapeutical options, the re-analysis of newly developed metastasis will become increasingly important.

K-RAS Associated Gene-Mutation-Based Algorithm for Prediction of Treatment Response of Patients with Subtypes of Breast Cancer and Especially Triple-Negative Cancer.

There is an urgent need for developing new biomarker tools to accurately predict treatment response of breast cancer, especially the deadly triple-negative breast cancer. We aimed to develop gene-mutation-based machine learning (ML) algorithms as biomarker classifiers to predict treatment response of first-line chemotherapy with high precision. Random Forest ML was applied to screen the algorithms of various combinations of gene mutation profiles of primary tumors at diagnosis using a TCGA Cohort (n = 399) with up to 150 months follow-up as a training set and validated in a MSK Cohort (n = 807) with up to 220 months follow-up. Subtypes of breast cancer including triple-negative and luminal A (ER+, PR+ and HER2-) were also assessed. The predictive performance of the candidate algorithms as classifiers was further assessed using logistic regression, Kaplan-Meier progression-free survival (PFS) plot, and univariate/multivariate Cox proportional hazard regression analyses. A novel algorithm termed the 12-Gene Algorithm based on mutation profiles of KRAS, PIK3CA, MAP3K1, MAP2K4, PTEN, TP53, CDH1, GATA3, KMT2C, ARID1A, RunX1, and ESR1, was identified. The performance of this algorithm to distinguish non-progressed (responder) vs. progressed (non-responder) to treatment in the TCGA Cohort as determined using AUC was 0.96 (95% CI 0.94-0.98). It predicted progression-free survival (PFS) with hazard ratio (HR) of 21.6 (95% CI 11.3-41.5) (p &lt; 0.0001) in all patients. The algorithm predicted PFS in the triple-negative subgroup with HR of 19.3 (95% CI 3.7-101.3) (n = 42, p = 0.000). The 12-Gene Algorithm was validated in the MSK Cohort with a similar AUC of 0.97 (95% CI 0.96-0.98) to distinguish responder vs. non-responder patients, and had a HR of 18.6 (95% CI 4.4-79.2) to predict PFS in the triple-negative subgroup (n = 75, p &lt; 0.0001). The novel 12-Gene algorithm based on multitude gene-mutation profiles identified through ML has a potential to predict breast cancer treatment response to therapies, especially in triple-negative subgroups patients, which may assist personalized therapies and reduce mortality.

Proxalutamide in patients with AR-positive metastatic breast cancer: Results from an open-label multicentre phase Ib study and biomarker analysis

AimProxalutamide is a novel second-generation non-steroidal androgen receptor (AR) antagonist. This study aimed to evaluate the preliminary efficacy and safety of proxalutamide in patients with AR-positive metastatic breast cancer (AR+ mBC). MethodsIn this open-label, dose-expansion, multicentre phase Ib trial, patients with AR+ mBC (immunohistochemistry [IHC] ≥1%) received proxalutamide orally once daily. Two proxalutamide dose cohorts (cohort A: 200 mg; cohort B: 300 mg) were sequentially investigated. Primary endpoints were disease control rate (DCR) at 8 and 16 weeks and recommended phase II dose (RP2D). ResultsForty-five patients with three median lines (range, 1–13) prior systemic therapy were enrolled (cohort A, n = 30; cohort B, n = 15). Among 39 evaluable patients, DCR at 8 and 16 weeks was 25.6% (95% confidence interval [CI], 11.9–39.4%), with 26.9% in cohort A and 23.1% in cohort B. No patient achieved partial response or complete response. Proxalutamide 200 mg/day was determined as RP2D. The 6-month progression-free survival (PFS) rate was 19.6% (95% CI, 10.2–37.5%). In the triple-negative subgroup, DCR at 8 weeks was 38.5%, with median PFS of 9.1 months (95% CI, 7.8–NA) in those who achieved response at 8 weeks (n = 5). Most common grade 3/4 adverse events were aspartate aminotransferase increase (8.9%) and γ-glutamyltransferase increase (8.9%). By biomarker analysis, patients with moderate AR expression of IHC (26%–75%), PIK3CA pathogenic mutations, or <60 ng/ml cell-free DNA yield showed longer PFS. ConclusionProxalutamide showed promising anti-tumour activity with good tolerability in patients with heavily pretreated AR+ mBC, supporting further investigation. Trial registrationThis clinical study was prospectively registered at chinadrugtrials.org.cn (Identifier: CTR20170757) and clinical trials.gov (Identifier: NCT04103853).

Clinicopathological characteristics and prognosis in women with breast cancer affected by COVID 19.

e22517 Background: there are few reported series n women with breast cancer (BC) and COVID-19, a better prognosis has been observed, with a lower rate of hospitalization and mortality than other neoplasms. Methods: We conducted a restrospective, non-experimental, observational, single center, study with a sample of 69 patients with BC who had presented COVID-19, in the period between March 2020 to August 2021. Clinicopathological characteristics of patients with BC were compared between severe and non-severe covid 19 groups, as well as hospitalized and non-hospitalized patients. An analysis of possible risk factors associated with severe disease and hospitalization was performed. Results: 69 cases were reported, median age 52y, mean BMI 25.2, ECOG 0-1: 97%. Smoking history in 24%, diabetes and hypertension were the most frequent comorbidities. The most frequent histology was ductal carcinoma in 80.6%, 73.8% showed ER + and 69.3% PR +, HER2 was overexpressed in 9.2%. The early stages predominated, I 22 (31.3%), II 25 (37.3%), III in 12 (17.9%) and IV in 6 (9%). The most frequents symptoms of COVID-19 were fatigue 70.1%, fever 65.7%, cough 59.7%, headache 56.7%, hyposmia 47.8%, dysgeusia 38.8%. A total of 53 (76.8%) mild cases, 14 (20.3) severe cases and 2 (2.9%) critical cases were registered. The 89.9% (62 patients) were treated as an outpatient basis, while 7 (10.1%) required hospitalization. Active treatment (&lt; 45 days) at the time of COVID-19 was hormonal therapy 36 (50.7%), chemotherapy 11 (16.4%), anti-HER2 in 3 (4.5%), immunotherapy in 1.5%, targeted treatment in 4 (6.0%), surgery in 7 (10.4%) and radiotherapy in 1 (1.5%) patient. When comparing the severe and non-severe groups, as well as hospitalized versus non-hospitalized, we observed no difference between the clinicopathological characteristics. Then, we serch for possible risk factors, in wich, surgery in a period of less than 3 months increases the risk of severity OR 1,297 (95% CI 1,112-1,514), the risk of hospitalization increased in the triple negative subgroup OR 1,143 (95% CI, 1,035- 1,262), surgery less than 3 months OR 1,116 (1,014-1,229) and chemotherapy less than 45 days OR 1,217 (95% CI, 1,024-1,447). Conclusions: In patients with BC, the prevalence of severe or critical COVID-19 was 23% and the hospitalizacion rate 10%. No patient died from this infection. The clinical and pathological characteristics of BC do not appear to increase the risk of severe COVID-19 or the rate of hospitalization. Surgery performed in a period of less than 3 months is marginally associated with an increased risk of severe disease. Chemotherapy, targeted therapy, and immunotherapy do not modify the risk of severe disease; however, higher Ki 67, triple negative subgroup, surgery and chemotherapy showed a slight increase in risk of hospitalization.

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

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