Multiomics of HER2-low triple-negative breast cancer identifies a receptor tyrosine kinase-relevant subgroup with therapeutic prospects.

To provide complementary information and reveal the molecular characteristics and therapeutic insights of HER2-low breast cancer, we performed this multiomics study of hormone receptor-negative (HR-) and HER2-low breast cancer, also known as HER2-low triple-negative breast cancer (TNBC), and identified 3 subgroups: basal-like, receptor tyrosine kinase-relevant (TKR), and mesenchymal stem-like. These 3 subgroups had distinct features and potential therapeutic targets and were validated in external data sets. Interestingly, the TKR subgroup (which exists in both HR+ and HR- breast cancer) had activated HER2 and downstream MAPK signaling. In vitro and in vivo patient-derived xenograft experiments revealed that pretreatment of the TKR subgroup with a tyrosine kinase inhibitor (lapatinib or tucatinib) could inhibit HER2 signaling and induce accumulated expression of nonfunctional HER2, resulting in increased sensitivity to the sequential HER2-targeting, Ab-drug conjugate DS-8201. Our findings identify clinically relevant subgroups and provide potential therapeutic strategies for HER2-low TNBC subtypes.

Combined Single-Cell and Spatial Transcriptomics Reveal the Metabolic Evolvement of Breast Cancer during Early Dissemination.

Breast cancer is now the most frequently diagnosed malignancy, and metastasis remains the leading cause of death in breast cancer. However, little is known about the dynamic changes during the evolvement of dissemination. In this study, 65 968 cells from four patients with breast cancer and paired metastatic axillary lymph nodes are profiled using single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics. A disseminated cancer cell cluster with high levels of oxidative phosphorylation (OXPHOS), including the upregulation of cytochrome C oxidase subunit 6C and dehydrogenase/reductase 2, is identified. The transition between glycolysis and OXPHOS when dissemination initiates is noticed. Furthermore, this distinct cell cluster is distributed along the tumor's leading edge. The findings here are verified in three different cohorts of breast cancer patients and an external scRNA-seq dataset, which includes eight patients with breast cancer and paired metastatic axillary lymph nodes. This work describes the dynamic metabolic evolvement of early disseminated breast cancer and reveals a switch between glycolysis and OXPHOS in breast cancer cells as the early event during lymph node metastasis.

Copy number amplification of ENSA promotes the progression of triple-negative breast cancer via cholesterol biosynthesis.

Copy number alterations (CNAs) are pivotal genetic events in triple-negative breast cancer (TNBC). Here, our integrated copy number and transcriptome analysis of 302 TNBC patients reveals that gene alpha-endosulfine (ENSA) exhibits recurrent amplification at the 1q21.3 region and is highly expressed in TNBC. ENSA promotes tumor growth and indicates poor patient survival in TNBC. Mechanistically, we identify ENSA as an essential regulator of cholesterol biosynthesis in TNBC that upregulates the expression of sterol regulatory element-binding transcription factor 2 (SREBP2), a pivotal transcription factor in cholesterol biosynthesis. We confirm that ENSA can increase the level of p-STAT3 (Tyr705) and activated STAT3 binds to the promoter of SREBP2 to promote its transcription. Furthermore, we reveal the efficacy of STAT3 inhibitor Stattic in TNBC with high ENSA expression. In conclusion, the amplification of ENSA at the 1q21.3 region promotes TNBC progression and indicates sensitivity to STAT3 inhibitors.

Cyclophosphamide-Free Adjuvant Chemotherapy for Ovarian Protection in Young Women With Breast Cancer: A Randomized Phase 3 Trial.

BACKGROUND: Chemotherapy-induced premature menopause leads to some consequences, including infertility. We initiated this randomized phase III trial to determine whether a cyclophosphamide-free adjuvant chemotherapy regimen would increase the likelihood of menses resumption and improve survival outcomes. METHODS: Young women with operable estrogen receptor-positive HER2-negative breast cancer after definitive surgery were randomly assigned to receive adjuvant epirubicin and cyclophosphamidefollowed by weekly paclitaxel (EC-wP) or epirubicin and paclitaxel followed by weekly paclitaxel (EP-wP). All patients received at least 5-year adjuvant endocrine therapy after chemotherapy. Two coprimary endpoints were the rate of menstrual resumption at 12 months after chemotherapy and 5-year disease-free survival in the intention-to-treat population. This study is registered at ClinicalTrials.gov (NCT01026116). All statistical tests were 2-sided. RESULTS: Between January 2011 and December 2016, 521 patients (median age = 34 years; interquartile range = 31-38 years) were enrolled, with 261 in the EC-wP group and 260 in the EP-wP group. The rate of menstrual resumption at 12 months after chemotherapy was 48.3% in EC-wP (95% confidence interval [CI] = 42.2% to 54.3%) and 63.1% in EP-wP (95% CI = 57.2% to 68.9%), with an absolute difference of 14.8% (95% CI = 6.37% to 23.2%, P < .001). The posthoc exploratory analysis by patient-reported outcome questionnaires indicated that pregnancy might occur in fewer women in the EC-wP group than in the EP-wP group. At a median follow-up of 62 months, the 5-year disease-free survival was 78.3% (95% CI = 72.2% to 83.3%) in EC-wP and 84.7% (95% CI = 79.3% to 88.8%) in EP-wP (stratified log-rank P = .07). The safety data were consistent with the known safety profiles of relevant drugs. CONCLUSIONS: The cyclophosphamide-free chemotherapy regimen might be associated with a higher probability of menses resumption.

Immune-Activated Regional Lymph Nodes Predict Favorable Survival in Early-Stage Triple-Negative Breast Cancer.

Immune response and immunotherapy play important roles in triple-negative breast cancer (TNBC). However, it is difficult to judge whether cancer is "immune-inactivated" or "immune-activated" by the carcinoma itself. The immune reaction of the microenvironment or the host to the tumor might be more informative. We assumed that clinically enlarged but pathologically negative regional lymph nodes served as an indicator for early immune response to tumors. First, we identified women with pN0 breast cancer disease from the current Surveillance, Epidemiology, and End Results database, and we compared the cN1 patients of breast cancer-specific survival (BCSS) with cN0 patients. Then, we extracted total RNA from 36 paired large (defined as minimum diameter more than 15 mm in size) and small lymph nodes (defined as maximum diameter less than 5 mm in size) from 12 TNBC, 12 HER2-enriched, and 12 luminal-like patients and performed RNA sequencing to explore the gene expression and cellular landscape of large nodes compared to small ones. Among 692 women with pathologically confirmed node-negative disease, cN1 patients unexpectedly had a better BCSS compared with cN0 in TNBC (adjusted hazard ratio 0.148, 95% CI, 0.040-0.546, P = 0.004) but not in other subtypes. Further transcriptome sequencing of 12 paired enlarged and small negative nodes from TNBC patients revealed that increased immune activation signaling (e.g., interferon-gamma response pathways) and abundant immune cells (activated dendritic cells, CD4+ and CD8+ T-cells) were more frequently observed in enlarged nodes. Our data implied that early immune activation in regional lymph nodes in TNBC might affect survival.