Background: Everolimus is beneficial for patients with hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2−) advanced breast cancer (ABC). However, some patients developed drug resistance and the well-established predictor for everolimus efficacy was limited. Objectives: The study was designed to evaluate the efficacy of everolimus in different treatment lines and identify several clinicopathological markers to estimate everolimus efficacy in patients with HR+/HER2− ABC. Design: This was a retrospective and multicenter study. Methods: Between 2014 and 2022, more than 2000 patients with tumors who received everolimus were collected from multiple cancer centers in China (National Cancer Center, Chinese PLA General Hospital, Peking University Cancer Hospital & Institute). A training cohort and two validation cohorts were developed. Results: The training cohort included 338 patients. The median progression-free survival (PFS) for everolimus was 5.6 months, with an objective response rate of 25.1% and a clinical benefit rate of 54.4%. PFS was significantly worse from first-line (1L) to second-line (2L) to third-line (3L), with PFS 1L for 13.5 months, PFS 2L for 6.1 months, and PFS 3L for 4.1 months ( p = 2.9e−6, hazard ratio (HR) = 0.70, 95% confidence interval (CI) = 0.61–0.82). The clinicopathological characteristics, including post-1L everolimus treatment, Ki67 index of more than 40%, more than two metastatic sites at first recurrence, and receiving adjuvant chemotherapy, were independent risk factors for PFS. A predictive model for everolimus efficacy was established using these four factors. In the low-risk group, patients achieved a median PFS of 12.6 months, significantly longer compared to 2.7 months for those in the high-risk group ( p = 2.4e−64, HR = 9.41, 95% CI = 7.05–12.56). The area under the curve was 0.96, 0.95, and 0.94 for 6-month, 1-year, and 3-year PFS, respectively. Internal validation cohort (PFS 18.4 vs 3.1 months, p = 3.6e−11, HR = 3.78, 95% CI = 2.49–5.74) and external validation cohort (PFS 13.5 vs 3.1 months, p = 2.9e−10, HR = 11.53, 95% CI = 4.68–28.37) confirmed its power for estimating clinical benefits of everolimus. Conclusion: A predictive model was successfully established to predict survival outcomes for everolimus in patients with HR+/HER2− ABC, which may provide references for the management of everolimus in Chinese patients with HR+/HER2− ABC.

BACKGROUND:Patients with hormone receptor-positive (HR+), human epidermal growth factor receptor-2 negative (HER2-) early breast cancer (EBC) with high-risk clinicopathological features face an increased risk of recurrence. This study explored the evolving treatment landscape and clinical outcomes in patients with EBC using a nationwide database. PATIENTS AND METHODS:The study cohort comprised HR+/HER2-, stages 1-3, patients with EBC who underwent surgery and received adjuvant endocrine therapy (AET) from January 2013 to March 2021. High-risk patients were defined by ≥4 positive axillary lymph nodes, or 1-3 positive lymph node(s) with at least one high-risk feature (histologic grade 3, tumor size ≥5 cm, or Ki-67 ≥20%). A low-risk cohort included patients not meeting the criteria. Survival analysis was conducted with a cutoff of September 2021. RESULTS:The study included 4088 eligible patients (1310 high-risk patients and 2778 low-risk patients). High-risk patients were more likely to receive adjuvant chemotherapy and radiotherapy compared to low-risk patients. From 2013 to 2021, an increasing proportion of patients received aromatase inhibitors and ovarian function suppression as part of their AET. The 2-, 5-, and 7-year invasive disease-free survival for high-risk cohort were 90.67%, 75.26%, and 57.10%, respectively, these rates were notably higher for low-risk cohort at 97.14%, 89.85%, and 84.83%. High-risk patients demonstrated a higher risk of recurrence or death compared with low-risk patients (hazard ratio, 2.38; 95% CI, 1.82-3.12). CONCLUSION:In the setting of standard or even intensive AET, patients with EBC with high-risk features still present high recurrence risk, highlighting the urgent need for innovative adjuvant treatment strategies.

Background:Cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) and everolimus (EVE) are effective for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC). However, the efficacy of different sequences of CDK4/6i and EVE are largely unknown. The study aimed to explore the efficacy of different sequences in China. Methods:146 patients with HR+/HER2- MBC who received both CDK4/6i and EVE in salvage setting were collected. Objective response rate (ORR), clinical benefit rate (CBR), progression-free survival (PFS), and overall survival (OS) were investigated. Results:56 patients received CDK4/6i prior to EVE (Group A), 90 patients received CDK4/6i subsequent to EVE (Group B). The median PFS of CDK4/6i and EVE in Group A vs Group B were 8.4m and 2.5m vs 4.6m and 6.1m respectively. The total PFS of first-line and second-line endocrine therapy were not different between Group A and Group B [13.1m vs 17.7m (P = 0.330, HR = 0.738, 95%CI: 0.399-1.365)]. The 5y OS of patients in Group A or Group B were 62.0 % vs 57.4 %, P = 0.569. Conclusions:We found that no matter CDK4/6i or EVE was used first, the survival were not significantly different between Group A and Group B. Both can be clinical options.

Abstract Objective Everolimus (EVE), a mammalian target of rapamycin (mTOR) inhibitor, has been shown to prolong survival of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-), advanced breast cancer (ABC) with endocrine resistance. Preclinical studies have suggested that mTOR is closely associated with the tumor immune microenvironment (TME). We aimed to explore the tumor heterogeneity of TME between patients with different response to everolimus (EVE), and identify potential markers to predict efficacy of EVE in premenopausal patients with HR+/HER2−, advanced breast cancer (ABC) suffering endocrine resistance. Methods Patients were divided into two groups according to the best response to EVE: the responsive subgroup (RS) and the non-responsive subgroup (NRS). Postoperative tumor tissue from patients who received EVE was collected for whole exome sequencing. Transcript abundance of 126 distinct tumor regions of interest (ROIs) were quantitated using digital spatial profiling, including 42 tumor cell zones (TCZs), 42 immune cell zones (ICZs), and 42 stroma cell zones (SCZs). Based on investigation in multiple discrete areas, differences in cell components, function and pathway, gene expression and immune cell infiltration between RS and NRS were investigated. Results Totally, 93 differentially expressed genes (DEGs) were identified in the ICZs, 174 DEGs in the TCZs, and 197 DEGs in the SCZs, using p< 0.05 and |log2FC >1| as the screening criterion. Among all the subgroup analyses on different ROIs, the statistical significance of PIP gene was the highest (ICZs: p=2.6E-12, TCZs: p=1.25E-20, SCZs: p=2.0E-18) in the comparison of RS and NRS. Moreover, we found that PIP was highly expressed in NRS and patients with a progression-free survival < 1 year. The receptor-legend analysis showed that, the intra-and inter-cellular communication in RS was mainly mediated by interaction between CCL-CCR family, while NRS mainly by COL family complex. Comparing all cell components extracted from each ROI, no statistical differences were found between RS and NRS, only a statistical trend in the SCZs (p=0.098). Further cell classification analysis showed fibroblasts highest in TCZs and SCZs, macrophages in ICZs. Compared to NRS, in TCZs, fibroblasts were significantly increased (p=0.01), and plasma cells (p=0.02) and neutrophils (p=0.03) were decreased in RS. In SCZs, the downregulated fibroblasts (p=0.04) and enhanced plasma cells (p=0.01) were observed in NRS. In ICZs, pDCs (p=0.048) and neutrophils (p=0.006) were significantly elevated in NRS compared with RS. Conclusion The utility of digital spatial gene expression profiling might provide some references to predict the efficacy of EVE in premenopausal patients with HR+/HER2- ABC with endocrine resistance. Citation Format: Yujing Tan, Fei Ma, Jiayu Wang, Pin Zhang, Binghe Xu, Liyan Xue, Ying Fan. Heterogeneity of tumor immune microenvironment to predict everolimus efficacy in premenopausal women with hormone receptor-positive/human epidermal growth factor receptor 2-negative adavanced 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 PO3-14-01.

Abstract Background Triple‐positive breast cancer (TPBC) is highly invasive and lacks well‐established treatment strategies, especially in patients with advanced stage disease. This study aimed to explore the efficacy of everolimus in patients with metastatic TPBC (mTPBC) in a multicenter real‐world setting. Methods A total of 2518 cancer patients who received everolimus‐based therapy were enrolled from three cancer institutes in China from 2014 to 2022. Their clinicopathological characteristics were collected from medical records. The indicators for the efficacy of everolimus were progression‐free survival (PFS), objective response rate (ORR) and clinical benefit rate (CBR). Results We collected 79 HER2‐enriched patients that were treated with everolimus‐based therapy, 43 of whom were mTPBC. The most commonly used therapeutic combinations was everolimus plus endocrine therapy (18/43, 41.9%). Among all combinations, everolimus plus chemotherapy plus trastuzumab developed the longest PFS of 10.9 months (95% CI: 1.5–20.3). Seventeen patients (32.6%) with mTPBC received everolimus as frontline treatment (1 L/2 L/3 L, FL), and 26 patients (67.4%) as backline treatment (>3 L, BL). Among all the population, the median PFS for everolimus was 4.5 months (range: 3.0–6.0), ORR was 30.2%, and CBR was 48.8%. PFSFL of 10.9 months was significantly longer than 4.0 months for PFSBL (p = 0.003, HR = 0.31, 95% CI: 0.14–0.67). ORRFL was 41.2%, showing no significance compared to ORRBL of 23.1% (one‐sided p = 0.11). CBRFL was observed better of 76.5% versus CBRBL of 46.2% (one‐sided p = 0.026). Conclusion Everolimus as frontline treatment achieves clinical benefits for Chinese patients with mTPBC, which may provide some references for the management of Chinese mTPBC patients.

Abstract Bone metastasis accounts for a frequent complication in advanced estrogen receptor-positive (ER+) breast cancer, with staggeringly high percentage up to 70%. However, our understanding of molecular mechanisms underlying bone metastasis remains insufficient. In our study, 216 differentially expressed genes (DEGs) related to bone metastasis in ER + breast cancer were screened out. Enrichment analysis showed that, DEGs were enriched in construction of tumor microenvironment, including extracellular matrix, cell adhesion molecules and blood vessel development. In-depth analysis was performed on 4 dominant overlapped genes to investigate their functional feasibility in immune regulation, prognosis and pharmacological application. The expression of COL1A1, COL1A2, COL3A1 and SPARC was elevated in bone metastasis evolution and potentially associated with poor prognosis, but with no statistical significance. Halofuginone targeted on COL1A1 was pharmacologically inhibit progress of bony metastasis. Our results indicated that, high expression of COL1A1, COL1A2, COL3A1 and SPARC could be served as biomarkers for bone metastasis screening, and halofuginone could be developed for new therapeutic option after further clinical investigation.