Eribulin is a non-taxane synthetic analogue approved in many countries as third-line treatment for the treatment of patients with metastatic breast cancer. In addition to its mitotic property, eribulin has non-mitotic properties including but not limited to, its ability to induce phenotypic reversal of epithelial to mesenchymal transition, vascular remodelling, reduction in immunosuppressive tumour microenvironment. Since approval, there has been a surge in studies investigating the application of eribulin as an earlier-line treatment and also in combination with other agents such as immunotherapy and targeted therapy across all breast cancer sub-types, including hormone receptor positive, HER2 positive and triple negative breast cancer, many demonstrating promising activity. This review will focus on the application of eribulin in the treatment of metastatic breast cancer across all subtypes including its role as an earlier-line agent, its toxicity profile, and potential future directions.

UNASSIGNED: The role of surgery in metastatic breast cancer (MBC) is currently controversial. Several novel statistical and deep learning (DL) methods promise to infer the suitability of surgery at the individual level.
UNASSIGNED: The objective of this study was to identify the most applicable DL model for determining patients with MBC who could benefit from surgery and the type of surgery required.
UNASSIGNED: We introduced the deep survival regression with mixture effects (DSME), a semi-parametric DL model integrating three causal inference methods. Six models were trained to make individualized treatment recommendations. Patients who received treatments in line with the DL models\' recommendations were compared with those who underwent treatments divergent from the recommendations. Inverse probability weighting (IPW) was used to minimize bias. The effects of various features on surgery selection were visualized and quantified using multivariate linear regression and causal inference.
UNASSIGNED: In total, 5269 female patients with MBC were included. DSME was an independent protective factor, outperforming other models in recommending surgery (IPW-adjusted hazard ratio [HR] = 0.39, 95% confidence interval [CI]: 0.19-0.78) and type of surgery (IPW-adjusted HR = 0.66, 95% CI: 0.48-0.93). DSME was superior to other models and traditional guidelines, suggesting a higher proportion of patients benefiting from surgery, especially breast-conserving surgery. The debiased effect of patient characteristics, including age, tumor size, metastatic sites, lymph node status, and breast cancer subtypes, on surgery decision was also quantified.
UNASSIGNED: Our findings suggested that DSME could effectively identify patients with MBC likely to benefit from surgery and the specific type of surgery needed. This method can facilitate the development of efficient, reliable treatment recommendation systems and provide quantifiable evidence for decision-making.

Background and Objectives: Patients with human epidermal growth factor receptor 2 (HER2) -positive, hormone receptor-positive (HR-positive) metastatic breast cancer (MBC) usually undergo trastuzumab emtansine (T-DM1) therapy in subsequent lines. Combining endocrine therapy (ET) with T-DM1 can improve treatment outcomes in this subtype. Therefore, this study aimed to investigate the benefits of using T-DM1 with ET in HER2-positive and HR-positive MBC. This study was the first to investigate the benefits of combining ET with T-DM1. Material and Methods: This study analyzed the medical records of patients with HER2-positive and HR-positive MBC who were treated with T-DM1 from June 2010 to December 2021. The patients were divided into groups based on whether they received concomitant ET with T-DM1. The primary endpoint was to determine the progression-free survival (PFS), while the secondary endpoints were overall survival (OS), objective response rate, and safety of the treatment. Results: Our analysis examined 88 patients, of whom 32 (36.4%) were treated with T-DM1 in combination with ET. The combination therapy showed a significant improvement in median PFS (15.4 vs. 6.4 months; p = 0.00004) and median OS (35.0 vs. 23.1 months; p = 0.026) compared to T-DM1 alone. The ORR was also higher in the combination group (65.6% vs. 29.3%; p = 0.026). Patients treated with pertuzumab priorly had reduced median PFS on T-DM1 compared to those who were not treated with pertuzumab (11.7 vs. 5.4 months, respectively; p < 0.01). T-DM1 demonstrated better median PFS in HER2 3+ patients compared to HER2 2+ patients, with an amplification ratio of >2.0 (10.8 vs 5.8 months, respectively; p = 0.049). The safety profiles were consistent with previous T-DM1 studies. Conclusions: The combination of T-DM1 with ET can significantly improve PFS and OS in patients with HER2-positive and HR-positive MBC. Our study suggests that prior pertuzumab treatment plus trastuzumab treatment might decrease T-DM1 efficacy.

In hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (MBC), cyclin-dependent kinase 4/6 inhibitors (CDK4/6is) have replaced endocrine therapy alone as the standard of care; however, several barriers to treatment initiation still exist. We assessed social determinants of health (SDOH) and other factors associated with the initiation of CDK4/6i for HR+/HER2- MBC in the Medicare population. Using a retrospective cohort design, patients aged ≥65 years and diagnosed during 2015-2017 were selected from the SEER-Medicare database. Time from MBC diagnosis to first CDK4/6i initiation was the study outcome. The effect of SDOH measures and other predictors on the outcome was assessed using the multivariable Fine and Gray hazard modeling. Of 752 eligible women, 352 (46.8%) initiated CDK4/6i after MBC diagnosis (median time to initiation: 27.9 months). In adjusted analysis, SDOH factors significantly associated with CDK4/6i initiation included high versus low median household income (HHI) (hazard ratio [HR] = 1.70; 95% CI = 1.03-2.81) and the percentage of population with high versus low Medicare-only coverage (HR = 1.54; 95% CI = 1.04-2.27). In summary, older Medicare patients with HR+/HER2- MBC residing in areas with high median HHI and a high proportion of Medicare-only coverage had higher rates of initiating CDK4/6i, suggesting inequitable access to these novel, effective treatments and a need for policy intervention.

BACKGROUND: Breast cancer (BC) is the world\'s largest tumor species in which hormone receptor-positive patients have relatively good prognosis. However, majority of patients will develop late resistance, one of the important factors is due to the loss of the original estrogen receptor (ER) expression.
METHODS: We conducted this study in 115 patients with BC who experienced second biopsy at Jiangsu Province Hospital (JSPH) and divided patients into two subgroups ER + to - and ER + to + . First, clinicopathological characteristics between two groups were evaluated. Second, we explored candidate genes related to BC ER intratumor heterogeneity by applying next-generation sequencing (NGS) in 42 patients. Multi-omics integrative analysis of tumor transcriptomic, cancer-related pathway, diagnostic and prognostic value and immune profile were conducted. Besides, preliminary assay were also used to evaluate the correlation between KMT2C and ERα (ESR1) expression. The CCK-8, 5-Ethynyl-2\'-deoxyuridine (EdU) assays, Transwell assays and the wound scratch tests were applied to explore the cellular interactions between KMT2C and BC.
RESULTS: We find the histological type (p = 0.008) and disease-free survival (DFS) (p = 0.004) were significantly different in two subgroups. In Cox survival analysis, metastasis (Hazard ratio (HR) > 1, p = 0.007) and neo-adjuvant (HR < 1, p < 0.001) are independent prognostic factors of DFS. Besides, by analyzing NGS results, we found four genes KMT2C, FGFR19, FGF1 and FGF4 were highly mutated genes in ER + to - subgroup. Furthermore, the gene KMT2C displayed significant diagnostic value and prognostic value in BC and pan-cancer. In addition, a positive correlation between KMT2C expression and immune infiltrating levels of T cell CD4 + , macrophage and neutrophil was found. In the end, Western blot and RT-qPCR assay were used and found KMT2C and ERα (ESR1) expressions are strongly positive correlated in mRNA and protein level. Inhibition of KMT2C significantly reduced proliferation, invasion, and migration of MCF7 cells.
CONCLUSIONS: People in two cohorts from JSPH presented different clinical characteristics and prognosis. The gene KMT2C may affect the progression of BC by regulating the molecular, epigenetic activity and immune infiltration. It may also serve as a novel prognostic biomarker for BC patients who underwent ER status converted from positive to negative.

OBJECTIVE: To compare CDK4/6 inhibitor (CDK4/6i) with endocrine therapy (ET) in the first- versus second-line setting for treatment of hormone receptor positive (HR+), HER2 negative, metastatic breast cancer (MBC) using real-world evidence.
METHODS: Patients with HR+, HER2 negative MBC, diagnosed between 2/3/2015 and 11/2/2021 and having ≥ 3 months follow-up were identified from the nationwide electronic health record-derived Flatiron Health de-identified database. Treatment cohorts included: (1) first-line ET with a CDK 4/6i (1st-line CDK4/6i) versus (2) first-line ET alone followed by second-line ET with a CDK4/6i (2nd-line CDK4/6i). Differences in baseline characteristics were tested using chi-square tests and two-sample t-tests. Time to third-line therapy, time to start of chemotherapy, and overall survival were compared using Kaplan-Maier method.
RESULTS: The analysis included 2771 patients (2170 1st-line CDK4/6i and 601 2nd-line CDK4/6i). Patients receiving 1st-line CDK4/6i were younger (75% vs 68% < 75 years old, p = 0.0001), less likely uninsured or not having insurance status documented (10% vs. 13%, p = 0.04), of better performance status (50% vs 43% with ECOG 0, p = 0.03), and more likely to have de novo MBC (36% vs. 24%, p < 0.001). Time to third-line therapy (49 vs 22 months, p < 0.001) and time to chemotherapy (68 vs 41 months, p < 0.001) were longer in those receiving first-line CDK4/6i. Overall survival (54 vs 49 months, p = 0.33) was similar between groups.
CONCLUSIONS: Use of CDK4/6i with first-, vs second-, line ET was associated with longer time to receipt of 3rd-line therapy and longer time to receipt of chemotherapy.

Mutations in the estrogen receptor alpha gene (ESR1) can lead to resistance to endocrine therapy (ET) in hormone receptor-positive (HR+)/ HER2- metastatic breast cancer (MBC). ESR1 mutations can be detected in up to 40 % of patients pretreated with ET in circulating tumor DNA (ctDNA). Data from prospective randomized trials highlight those patients with HR+/HER2- MBC with detectable ESR1 mutations experience better outcomes when receiving novel selective estrogen receptor degraders (SERDs). There is a high need for optimizing ESR1 testing strategies on liquid biopsy samples in HR+/HER2- MBC, including a hugh quality workflow implementation and molecular pathology reporting standardization. Our manuscript aims to elucidate the clinical and biological rationale for ESR1 testing in MBC, while critically examining the currently available guidelines and recommendations for this specific type of molecular testing on ctDNA. The objective will extend to the critical aspects of harmonization and standardization, specifically focusing on the pathology laboratory workflow. Finally, we propose a clear and comprehensive model for reporting ESR1 testing results on ctDNA in HR+/HER2- MBC.

OBJECTIVE: Adherence to oral anticancer treatments (OATs) is a critical issue in metastatic breast cancer (MBC) to enhance survivorship and quality of life. The study is aimed to analyze the main themes and attributes related to OATs in MBC patients. This research is part of a project titled \"Enhancing Therapy Adherence Among Metastatic Breast Cancer Patients\" designed to produce a predictive model of non-adherence, a decision support system, and guidelines to improve adherence to OATs.
METHODS: The study consists of an exploratory observational and qualitative analysis using a focus group method. A semi-structured interview guide was developed to handle relevant OAT themes. Wordcloud plots, network analysis, and sentiment analysis were performed.
RESULTS: Nineteen female MBC patients participated in the protocol (age mean 55.95, SD = 6.87). Four main themes emerged: (theme 1) individual clinical pathway; (theme 2) barriers to adherence; (theme 3) resources to adherence; (theme 4) patients\' perception of new technologies. The Wordcloud and network analysis highlighted the important role of treatment side effects and the relationship with the clinician in the modulation of adherence behavior. This result is consistent with the sentiment analysis underscoring patients experience fear of issues related to clinical values and ineffective communication and discontinuity of the doctor in charge of the patient care.
CONCLUSIONS: The study highlighted the key role of the individual, relational variables, and side effects as internal and external determinants influencing adherence to MBC. Finally, the opportunity offered by eHealth technology to connect with other patients with similar conditions and share experiences could be a relief for MBC patients.

BACKGROUND: We performed an updated meta-analysis to explore the value of locoregional surgery in de novo stage IV breast cancer patients.
METHODS: A literature search was conducted to identify randomized controlled trials comparing primary tumor resection with systemic therapy in de novo stage IV breast cancer. The hazard ratio (HR) of overall survival (OS), local relapse-free survival (LRFS), and distant relapse-free survival (DRFS) were estimated and pooled.
RESULTS: Six studies were eligible, including a total of 1368 patients. Both OS (HR = 0.86; 95 %CI: 0.77-0.96; p = 0.01; I2 = 45 %) and LRFS (HR = 0.35; 95 %CI: 0.20-0.62; p = 0.0003; I2 = 83 %) were significantly improved with locoregional surgery compared with systemic therapy alone. There was no significant difference in terms of DRFS (HR = 0.96; 95 %CI: 0.41-2.22; p = 0.92; I2 = 86 %). The OS benefit was more pronounced in hormone receptor-positive patients (HR = 0.79; p = 0.003) and HER2-negative patients (HR = 0.80; p = 0.003).
CONCLUSIONS: This study demonstrated that locoregional surgery conferred significant OS and LRFS benefits in de novo stage IV breast cancer patients and may serve as an alternative choice for selected patients.

BACKGROUND: Cyclin dependent kinase 4/6 inhibitors (CDK4/6i) are recommended 1st line treatments in HR+HER2- metastatic breast cancer. However, the impact of prior CDK4/6i on the natural history of brain metastases (BM) is not well described.
METHODS: We reviewed retrospective data for 363 patients with HR+HER2- BM who received a CDK4/6i (CDK-Y) between 1 Jan 2015 to 31 July 2021 and 299 patients with HR+HER2- BM who did not receive a CDK4/6i (CDK-N) between 1 Jan 2010 to 31 Dec 2014. CNS PFS and OS were assessed in patients who received CDK4/6i after BM. OS from the time of BM development was assessed between patients who received CDK4/6i before BM and the CDK-N cohort RESULTS: In the CDK-Y cohort of 363 patients, 203 (56 %) received a CDK4/6i before BM, 133 (37 %) received a CDK4/6i only after BM and 27 (7 %) received a CDK4/6i both before and after BM. Median CNS PFS was 21.4 months for patients receiving a CDK4/6i only after BM and 9.4 months for patients who received CDK4/6i both before and after BM (p = 0.006). Median OS was 24.9 months for patients receiving a CDK4/6i only after BM and 12.1 months for patients who received CDK4/6i both before and after BM (p = 0.0098). Median OS from time of BM development for patients receiving a CDK4/6i before BM versus the CDK-N cohort was 4.3 months and 7.7 months respectively (p = 0.0082).
CONCLUSIONS: CDK4/6i exposure prior to BM may lead to development of resistance mechanisms which in turn reduces CNS PFS and OS upon rechallenging with a CDK4/6i after BM development. This motivates investigation of biomarkers for patient selection.