Enhancing therapeutic efficacy in luminal androgen receptor triple-negative breast cancer: exploring chidamide and enzalutamide as a promising combination strategy.

Extensive exploration of the molecular subtypes of triple-negative breast cancer (TNBC) is critical for advancing precision medicine. Notably, the luminal androgen receptor (LAR) subtype has attracted attention for targeted treatment combining androgen receptor antagonists and CDK4/6 inhibitors. Unfortunately, this strategy has proven to be of limited efficacy, highlighting the need for further optimization. Using our center's comprehensive multiomics dataset (n = 465), we identified novel therapeutic targets and evaluated their efficacy through multiple models, including in vitro LAR cell lines, in vivo cell-derived allograft models and ex vivo patient-derived organoids. Moreover, we conducted flow cytometry and RNA-seq analysis to unveil potential mechanisms underlying the regulation of tumor progression by these therapeutic strategies. LAR breast cancer cells exhibited sensitivity to chidamide and enzalutamide individually, with a drug combination assay revealing their synergistic effect. Crucially, this synergistic effect was verified through in vivo allograft models and patient-derived organoids. Furthermore, transcriptomic analysis demonstrated that the combination therapeutic strategy could inhibit tumor progression by regulating metabolism and autophagy. This study confirmed that the combination of histone deacetylase (HDAC) inhibitors and androgen receptor (AR) antagonists possessed greater therapeutic efficacy than monotherapy in LAR TNBC. This finding significantly bolsters the theoretical basis for the clinical translation of this combination therapy and provides an innovative strategy for the targeted treatment of LAR TNBC.

SF3A2 promotes progression and cisplatin resistance in triple-negative breast cancer via alternative splicing of MKRN1.

Triple-negative breast cancer (TNBC) is the deadliest subtype of breast cancer owing to the lack of effective therapeutic targets. Splicing factor 3a subunit 2 (SF3A2), a poorly defined splicing factor, was notably elevated in TNBC tissues and promoted TNBC progression, as confirmed by cell proliferation, colony formation, transwell migration, and invasion assays. Mechanistic investigations revealed that E3 ubiquitin-protein ligase UBR5 promoted the ubiquitination-dependent degradation of SF3A2, which in turn regulated UBR5, thus forming a feedback loop to balance these two oncoproteins. Moreover, SF3A2 accelerated TNBC progression by, at least in part, specifically regulating the alternative splicing of makorin ring finger protein 1 (MKRN1) and promoting the expression of the dominant and oncogenic isoform, MKRN1-T1. Furthermore, SF3A2 participated in the regulation of both extrinsic and intrinsic apoptosis, leading to cisplatin resistance in TNBC cells. Collectively, these findings reveal a previously unknown role of SF3A2 in TNBC progression and cisplatin resistance, highlighting SF3A2 as a potential therapeutic target for patients with TNBC.

The HLA-I landscape confers prognosis and antitumor immunity in breast cancer.

Breast cancer is a highly heterogeneous disease with varied subtypes, prognoses and therapeutic responsiveness. Human leukocyte antigen class I (HLA-I) shapes the immunity and thereby influences the outcome of breast cancer. However, the implications of HLA-I variations in breast cancer remain poorly understood. In this study, we established a multiomics cohort of 1156 Chinese breast cancer patients for HLA-I investigation. We calculated four important HLA-I indicators in each individual, including HLA-I expression level, somatic HLA-I loss of heterozygosity (LOH), HLA-I evolutionary divergence (HED) and peptide-binding promiscuity (Pr). Then, we evaluated their distribution and prognostic significance in breast cancer subtypes. We found that the four breast cancer subtypes had distinct features of HLA-I indicators. Increased expression of HLA-I and LOH were enriched in triple-negative breast cancer (TNBC), while Pr was relatively higher in hot tumors within TNBCs. In particular, a higher Pr indicated a better prognosis in TNBCs by regulating the infiltration of immune cells and the expression of immune molecules. Using the matched genomic and transcriptomic data, we found that mismatch repair deficiency-related mutational signature and pathways were enriched in low-Pr TNBCs, suggesting that targeting mismatch repair deficiency for synthetic lethality might be promising therapy for these patients. In conclusion, we presented an overview of HLA-I indicators in breast cancer and provided hints for precision treatment for low-Pr TNBCs.

Genetic interactions reveal distinct biological and therapeutic implications in breast cancer.

Co-occurrence and mutual exclusivity of genomic alterations may reflect the existence of genetic interactions, potentially shaping distinct biological phenotypes and impacting therapeutic response in breast cancer. However, our understanding of them remains limited. Herein, we investigate a large-scale multi-omics cohort (n = 873) and a real-world clinical sequencing cohort (n = 4,405) including several clinical trials with detailed treatment outcomes and perform functional validation in patient-derived organoids, tumor fragments, and in vivo models. Through this comprehensive approach, we construct a network comprising co-alterations and mutually exclusive events and characterize their therapeutic potential and underlying biological basis. Notably, we identify associations between TP53mut-AURKAamp and endocrine therapy resistance, germline BRCA1mut-MYCamp and improved sensitivity to PARP inhibitors, and TP53mut-MYBamp and immunotherapy resistance. Furthermore, we reveal that precision treatment strategies informed by co-alterations hold promise to improve patient outcomes. Our study highlights the significance of genetic interactions in guiding genome-informed treatment decisions beyond single driver alterations.

IL1R2 blockade alleviates immunosuppression and potentiates anti-PD-1 efficacy in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited therapeutic options. Interleukin-1 receptor type 2 (IL1R2) promotes breast tumor-initiating cell (BTIC) self-renewal and tumor growth in TNBC, indicating that targeting it could improve patient treatment. Here, we observed that IL1R2 blockade strongly attenuated macrophage recruitment and the polarization of tumor-associated macrophages (TAMs) to inhibit BTIC self-renewal and CD8+ T cell exhaustion, which resulted in reduced tumor burden and prolonged survival in TNBC mouse models. IL1R2 activation by TAM-derived IL1ß increased PD-L1 expression by interacting with the transcription factor yin yang 1 (YY1) and inducing YY1 ubiquitination and proteasomal degradation in both TAMs and TNBC cells. Loss of YY1 alleviated the transcriptional repression of c-Fos, which is a transcriptional activator of PD-L1. Combined treatment with an IL1R2-neutralizing antibody and anti-PD-1 led to enhanced anti-tumor efficacy and reduced TAMs, BTICs, and exhausted CD8+ T cells. These results suggest that IL1R2 blockade might be a strategy to potentiate immune checkpoint blockade efficacy in TNBC to improve patient outcomes.

Elongin B promotes breast cancer progression by ubiquitinating tumor suppressor p14/ARF.

Elongin B (ELOB), a pivotal element in the ELOB/c-Cullin2/5-SOCS-box E3 ubiquitin-protein ligase complex, plays a significant role in catalyzing the ubiquitination and subsequent degradation of a broad spectrum of target proteins. Notably, it is documented to facilitate these processes. However, the regulatory role of ELOB in breast cancer remains ambiguous. In this study, through bio-informatic analysis of The Cancer Genome Atlas and Fudan University Shanghai Cancer Center database, we demonstrated that ELOB was over-expressed in breast cancer tissues and was related to unfavorable prognosis. Additionally, pathway enrichment analysis illustrated that high expression of ELOB was associated with multiple cancer promoting pathways, like cell cycle, DNA replication, proteasome and PI3K - Akt signaling pathway, indicating ELOB as a potential anticancer target. Then, we confirmed that both in vivo and in vitro, the proliferation of breast cancer cells could be significantly suppressed by the down-regulation of ELOB. Mechanically, immunoprecipitation and in vivo ubiquitination assays prompted that, as the core element of Cullin2-RBX1-ELOB E3 ligase (CRL2) complex, ELOB regulated the ubiquitination and the subsequent degradation of oncoprotein p14/ARF. Moreover, the anticancer efficacy of erasing ELOB could be rescued by simultaneous knockdown of p14/ARF. Finally, through analyzing breast cancer tissue microarrays and western blot of patient samples, we demonstrated that the expression of ELOB in tumor tissues was elevated in compared to adjacent normal tissues. In conclusion, ELOB is identified to be a promising innovative target for the drug development of breast cancer by promoting the ubiquitination and degradation of oncoprotein p14/ARF.

Effects of dietary intervention on human diseases: molecular mechanisms and therapeutic potential.

Diet, serving as a vital source of nutrients, exerts a profound influence on human health and disease progression. Recently, dietary interventions have emerged as promising adjunctive treatment strategies not only for cancer but also for neurodegenerative diseases, autoimmune diseases, cardiovascular diseases, and metabolic disorders. These interventions have demonstrated substantial potential in modulating metabolism, disease trajectory, and therapeutic responses. Metabolic reprogramming is a hallmark of malignant progression, and a deeper understanding of this phenomenon in tumors and its effects on immune regulation is a significant challenge that impedes cancer eradication. Dietary intake, as a key environmental factor, can influence tumor metabolism. Emerging evidence indicates that dietary interventions might affect the nutrient availability in tumors, thereby increasing the efficacy of cancer treatments. However, the intricate interplay between dietary interventions and the pathogenesis of cancer and other diseases is complex. Despite encouraging results, the mechanisms underlying diet-based therapeutic strategies remain largely unexplored, often resulting in underutilization in disease management. In this review, we aim to illuminate the potential effects of various dietary interventions, including calorie restriction, fasting-mimicking diet, ketogenic diet, protein restriction diet, high-salt diet, high-fat diet, and high-fiber diet, on cancer and the aforementioned diseases. We explore the multifaceted impacts of these dietary interventions, encompassing their immunomodulatory effects, other biological impacts, and underlying molecular mechanisms. This review offers valuable insights into the potential application of these dietary interventions as adjunctive therapies in disease management.

Clinical sequencing defines the somatic and germline mutation landscapes of Chinese HER2-Low Breast Cancer.

More than half of the breast cancer initially labeled as human epidermal growth factor receptor 2 (HER2)-negative actually exhibited low HER2 levels (IHC 1+ or IHC 2+/FISH-) and were classified as HER2-low breast cancer. Previous research emphasized the significant biological heterogeneity in HER2-low breast cancer, highlighting the importance of accurately characterizing HER2-low tumors to promote the precise management of antibody‒drug conjugates. In this study, we established a large-scale targeted sequencing cohort (N = 1907) representing Chinese HER2-low breast cancer patients with detailed clinical annotation. Our research findings revealed that HER2-low breast cancer demonstrated distinct clinical pathological characteristics and mutation landscapes compared to HER2-zero group. When compared to HER2-zero tumors, HER2-low tumors exhibited a higher proportion of Luminal B subtypes and better disease-free survival. In hormone receptor (HR)-positive breast cancer, HER2-low group showed a higher frequency of GATA3 somatic mutations, BRCA2 germline mutations, and mutations in the DNA damage repair pathway. In contrast, in HR-negative breast cancer, the HER2-low group displayed a higher frequency of PIK3CA mutations and PI3K pathway alterations. These findings offered valuable insights for the precise targeted treatment of HER2-low breast cancer in different HR statuses.

Integrated multiomic profiling of breast cancer in the Chinese population reveals patient stratification and therapeutic vulnerabilities.

Molecular profiling guides precision treatment of breast cancer; however, Asian patients are underrepresented in publicly available large-scale studies. We established a comprehensive multiomics cohort of 773 Chinese patients with breast cancer and systematically analyzed their genomic, transcriptomic, proteomic, metabolomic, radiomic and digital pathology characteristics. Here we show that compared to breast cancers in white individuals, Asian individuals had more targetable AKT1 mutations. Integrated analysis revealed a higher proportion of HER2-enriched subtype and correspondingly more frequent ERBB2 amplification and higher HER2 protein abundance in the Chinese HR+HER2+ cohort, stressing anti-HER2 therapy for these individuals. Furthermore, comprehensive metabolomic and proteomic analyses revealed ferroptosis as a potential therapeutic target for basal-like tumors. The integration of clinical, transcriptomic, metabolomic, radiomic and pathological features allowed for efficient stratification of patients into groups with varying recurrence risks. Our study provides a public resource and new insights into the biology and ancestry specificity of breast cancer in the Asian population, offering potential for further precision treatment approaches.

Somatic mutations in a multigene panel and impact on prognosis based on TP53 status in Chinese HER2-positive patients undergoing neoadjuvant therapy: A single-institution retrospective cohort.

BACKGROUND: Gene mutations play a crucial role in the occurrence and development of tumors, particularly in breast cancer (BC). Neoadjuvant therapy (NAT) has shown greater clinical benefit in HER2-positive breast cancer. However, further clinical investigation is needed to fully understand the correlation between genetic mutations and NAT efficacy and the long-term prognosis in HER2-positive BC. METHODS: This was a retrospective cohort study of 222 patients receiving NAT between 2017 and 2021 in the Department of Breast Surgery of Fudan University Shanghai Cancer Center. Tumor samples from these patients were subjected to Next Generation Sequencing (NGS) to analyze mutations in 513 cancer-related genes. This study aimed to investigate the association between these genetic mutations and postoperative pathological complete response (pCR), as well as their impact on disease-free survival (DFS). RESULTS: In total, 48.65% patients reached pCR, ER-negative status (p < 0.001), PR-negative status (p < 0.001), Ki67 ≥ 20 (p = 0.011), and dual-targeted therapy (p < 0.001) were all associated with enhanced pCR rates. The frequency of somatic alterations in TP53 (60%), PIK3CA (15%), and ERBB2 (11%) was highest. In the HER2+/HR- cohort, patients who achieved pCR had a significant benefit in prognosis (HR = 3.049, p = 0.0498). KMT2C (p = 0.036) and TP53 (p = 0.037) mutations were significantly increased in patients with DFS events. Moreover, TP53 mutations had prognostic significance in HER2-positive BC patients with HR-negative (HR = 3.712, p = 0.027) and pCR (HR = 6.253, p = 0.027) status and who received herceptin-only targeted therapy (HR = 4.145, p = 0.011). CONCLUSIONS: The genetic mutation profiles of Chinese HER2+ patients who received NAT were discrepant with respect to HR status or DFS events. TP53 mutations have significant prognostic value in patients with NAT for HER2-positive BC and patients benefit differently depending on HR status, the neoadjuvant regimen and response, which highlights the significance of genetic factors in treatment customization based on individual genetic and clinical characteristics.

Rational and trial design of FASCINATE-N: a prospective, randomized, precision-based umbrella trial.

Background: With our growing insight into the molecular heterogeneity and biological characteristics of breast cancer, individualized treatment is the future of cancer treatment. In this prospective Fudan University Shanghai Cancer Center Breast Cancer Precision Platform Series study - neoadjuvant therapy (FASCINATE-N) trial, we classify breast cancer patients using multiomic characteristics into different subtypes to evaluate the efficacy of precision-based targeted therapies compared to standard neoadjuvant chemotherapy. Methods and design: The FASCINATE-N trial is a prospective, randomized, precision-based umbrella trial that plans to enroll 716 women with early breast cancer. After enrollment, patients will first be divided into three groups: hormone receptor (HR)+/human epidermal growth factor receptor 2 (HER2)-, HER2+, and HR-/HER2-. The HR+/HER2- patients are further stratified using fusion and clustering of similarity network fusion (SNF) algorithm into four subtypes; HER2+ patients are divided into HR+/HER2+ and HR-/HER2+ subtypes; and HR-/HER2- patients are stratified using the Fudan University Shanghai Cancer Center classification. For the assignment of drugs to patients, Bayesian methods of adaptive randomization will be used. The primary endpoint is pathological complete response rate; secondary endpoints include 3-year invasive disease-free survival, overall response rate, and toxicities according to common terminology criteria for adverse events (CTCAE) scale version 4.0 and the ratio of patients with complete cell cycle arrest (Ki67 < 2.7%) in HR+/HER2+ breast cancer. Discussion: The goal of our trial is to test the efficacy of our subtyping-based treatment in a neoadjuvant setting and to conduct a pilot study into the efficacy of targeted therapies within each precision-based subtype. The precision-based treatment arm can be updated with the refinement of our subtyping method, the discovery of new targets, and the development of novel targeted drugs. Our trial offers a unique opportunity to provide patients with individualized neoadjuvant therapy and test promising novel treatments that may further benefit patients. Trial registration: ClinicalTrials.gov identifier: NCT05582499 (https://classic.clinicaltrials.gov/ct2/show/NCT05582499).

Rational and trial design of FASCINATE-N (Fudan University Shanghai Cancer Center Breast Cancer Precision Platform Series study- neoadjuvant therapy): a prospective, randomized, precision-based umbrella trial Our FASCINATE-N trial is a prospective, randomized, precision-based umbrella trial that plans to enroll 716 women with early breast cancer. We will first divide patients into three groups: hormone receptor (HR)+/human epidermal growth factor receptor 2 (HER2)−, HER2+, and HR−/HER2−. Then, we will further classify patients using multiomic characteristics into different subtypes to evaluate the efficacy of precision-based targeted therapies compared to standard neoadjuvant chemotherapy. The goal of our trial is to test the efficacy of our subtyping-based treatment in a neoadjuvant setting and to conduct a pilot study into the efficacy of targeted therapies within each precision-based subtype. The precision-based treatment arm can be updated with the refinement of our subtyping method, the discovery of new targets and the development of novel targeted drugs. Our trial offers a unique opportunity to provide patients with individualized neoadjuvant therapy and test promising novel treatments that may further benefit patients.

CRTAM promotes antitumor immune response in triple negative breast cancer by enhancing CD8+ T cell infiltration.

The immunomodulatory (IM) subtype of triple negative breast cancer (TNBC) exhibits high expression of immune cell signaling genes and is more responsive to immunotherapy. However, the specific mechanism underlying this phenomenon remains unclear. One of the potential key genes appears to be the cytotoxic and regulatory T cell molecule (CRTAM). A cohort of 360 previously untreated TNBC patients from Fudan University Shanghai Cancer Center (FUSCC) underwent RNA sequencing analysis of their primary tumor tissue. Combined with three RNA-seq datasets obtained from the GEO database, a LASSO regression analysis was conducted to identify genes specific to the IM type of TNBC. Our findings revealed elevated CRTAM expression in the IM-type TNBC, which correlated with a favorable overall survival and recurrence-free survival in TNBC patients. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated a strong association between CRTAM and immune responses as well as immune system processes. Notably, CRTAM overexpression induced STAT1 phosphorylation and upregulation of interferon-stimulated genes. We also found that CRTAM enhanced tumor-associated immune cell infiltration, especially CD8+ T cells, which may be related to the increased expression of MHC class I molecules caused by CRTAM overexpression. These results suggest that CRTAM may serve as a potential biomarker for predicting the efficacy of immunotherapy in TNBC.

ZNF689 deficiency promotes intratumor heterogeneity and immunotherapy resistance in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is an aggressive disease characterized by remarkable intratumor heterogeneity (ITH), which poses therapeutic challenges. However, the clinical relevance and key determinant of ITH in TNBC are poorly understood. Here, we comprehensively characterized ITH levels using multi-omics data across our center's cohort (n = 260), The Cancer Genome Atlas cohort (n = 134), and four immunotherapy-treated cohorts (n = 109). Our results revealed that high ITH was associated with poor patient survival and immunotherapy resistance. Importantly, we identified zinc finger protein 689 (ZNF689) deficiency as a crucial determinant of ITH formation. Mechanistically, the ZNF689-TRIM28 complex was found to directly bind to the promoter of long interspersed element-1 (LINE-1), inducing H3K9me3-mediated transcriptional silencing. ZNF689 deficiency reactivated LINE-1 retrotransposition to exacerbate genomic instability, which fostered ITH. Single-cell RNA sequencing, spatially resolved transcriptomics and flow cytometry analysis confirmed that ZNF689 deficiency-induced ITH inhibited antigen presentation and T-cell activation, conferring immunotherapy resistance. Pharmacological inhibition of LINE-1 significantly reduced ITH, enhanced antitumor immunity, and eventually sensitized ZNF689-deficient tumors to immunotherapy in vivo. Consistently, ZNF689 expression positively correlated with favorable prognosis and immunotherapy response in clinical samples. Altogether, our study uncovers a previously unrecognized mechanism underlying ZNF689 deficiency-induced ITH and suggests LINE-1 inhibition combined with immunotherapy as a novel treatment strategy for TNBC.

Targeting EMSY-mediated methionine metabolism is a potential therapeutic strategy for triple-negative breast cancer.

Cancer stem cells (CSCs) are the most intractable subpopulation of triple-negative breast cancer (TNBC) cells, which have been associated with a high risk of relapse and poor prognosis. However, eradication of CSCs continues to be difficult. Here, we integrate the multiomics data of a TNBC cohort (n = 360) to identify vital markers of CSCs. We discover that EMSY, inducing a BRCAness phenotype, is preferentially expressed in breast CSCs, promotes ALDH+ cells enrichment, and is positively correlated with poor relapse-free survival. Mechanistically, EMSY competitively binds to the Jmjc domain, which is critical for KDM5B enzyme activity, to reshape methionine metabolism, and to promote CSC self-renewal and tumorigenesis in an H3K4 methylation-dependent manner. Moreover, EMSY accumulation in TNBC cells sensitizes them to PARP inhibitors against bulk cells and methionine deprivation against CSCs. These findings indicate that clinically relevant eradication of CSCs could be achieved with a strategy that targets CSC-specific vulnerabilities in amino acid metabolism.

Optimising first-line subtyping-based therapy in triple-negative breast cancer (FUTURE-SUPER): a multi-cohort, randomised, phase 2 trial.

BACKGROUND: Triple-negative breast cancers display heterogeneity in molecular drivers and immune traits. We previously classified triple-negative breast cancers into four subtypes: luminal androgen receptor (LAR), immunomodulatory, basal-like immune-suppressed (BLIS), and mesenchymal-like (MES). Here, we aimed to evaluate the efficacy and safety of subtyping-based therapy in the first-line treatment of triple-negative breast cancer. METHODS: FUTURE-SUPER is an ongoing, open-label, randomised, controlled phase 2 trial being conducted at Fudan University Shanghai Cancer Center (FUSCC), Shanghai, China. Eligible participants were females aged 18-70 years, with an Eastern Cooperative Oncology Group performance status of 0-1, and histologically confirmed, untreated metastatic or recurrent triple-negative breast cancer. After categorising participants into five cohorts according to molecular subtype and genomic biomarkers, participants were randomly assigned (1:1) with a block size of 4, stratified by subtype, to receive, in 28-day cycles, nab-paclitaxel (100 mg/m2, intravenously on days 1, 8, and 15) alone (control group) or with a subtyping-based regimen (subtyping-based group): pyrotinib (400 mg orally daily) for the LAR-HER2mut subtype, everolimus (10 mg orally daily) for the LAR-PI3K/AKTmut and MES-PI3K/AKTmut subtypes, camrelizumab (200 mg intravenously on days 1 and 15) and famitinib (20 mg orally daily) for the immunomodulatory subtype, and bevacizumab (10 mg/kg intravenously on days 1 and 15) for the BLIS/MES-PI3K/AKTWT subtype. The primary endpoint was investigator-assessed progression-free survival for the pooled subtyping-based group versus the control group in the intention-to-treat population (all randomly assigned participants). Safety was analysed in all patients with safety records who received at least one dose of study drug. This study is registered with ClinicalTrials.gov (NCT04395989). FINDINGS: Between July 28, 2020, and Oct 16, 2022, 139 female participants were enrolled and randomly assigned to the subtyping-based group (n=69) or control group (n=70). At the data cutoff (May 31, 2023), the median follow-up was 22·5 months (IQR 15·2-29·0). Median progression-free survival was significantly longer in the pooled subtyping-based group (11·3 months [95% CI 8·6-15·2]) than in the control group (5·8 months [4·0-6·7]; hazard ratio 0·44 [95% CI 0·30-0·65]; p<0·0001). The most common grade 3-4 treatment-related adverse events were neutropenia (21 [30%] of 69 in the pooled subtyping-based group vs 16 [23%] of 70 in the control group), anaemia (five [7%] vs none), and increased alanine aminotransferase (four [6%] vs one [1%]). Treatment-related serious adverse events were reported for seven (10%) of 69 patients in the subtyping-based group and none in the control group. No treatment-related deaths were reported in either group. INTERPRETATION: These findings highlight the potential clinical benefits of using molecular subtype-based treatment optimisation in patients with triple-negative breast cancer, suggesting a path for further clinical investigation. Phase 3 randomised clinical trials assessing the efficacy of subtyping-based regimens are now underway. FUNDING: National Natural Science Foundation of China, Natural Science Foundation of Shanghai, Shanghai Hospital Development Center, and Jiangsu Hengrui Pharmaceuticals. TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

Guanosine diphosphate-mannose suppresses homologous recombination repair and potentiates antitumor immunity in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with poor prognosis. TNBCs with high homologous recombination deficiency (HRD) scores benefit from DNA-damaging agents, including platinum drugs and poly(ADP-ribose) polymerase (PARP) inhibitors, whereas those with low HRD scores still lack therapeutic options. Therefore, we sought to exploit metabolic alterations to induce HRD and sensitize DNA-damaging agents in TNBCs with low HRD scores. We systematically analyzed TNBC metabolomics and identified a metabolite, guanosine diphosphate (GDP)-mannose (GDP-M), that impeded homologous recombination repair (HRR). Mechanistically, the low expression of the upstream enzyme GDP-mannose-pyrophosphorylase-A (GMPPA) led to the endogenous up-regulation of GDP-M in TNBC. The accumulation of GDP-M in tumor cells further reduced the interaction between breast cancer susceptibility gene 2 (BRCA2) and ubiquitin-specific peptidase 21 (USP21), which promoted the ubiquitin-mediated degradation of BRCA2 to inhibit HRR. Therapeutically, we illustrated that the supplementation of GDP-M sensitized DNA-damaging agents to impair tumor growth in both in vitro (cancer cell line and patient-derived organoid) and in vivo (xenograft in immunodeficient mouse) models. Moreover, the combination of GDP-M with DNA-damaging agents activated STING-dependent antitumor immunity in immunocompetent syngeneic mouse models. Therefore, GDP-M supplementation combined with PARP inhibition augmented the efficacy of anti-PD-1 antibodies. Together, these findings suggest that GDP-M is a crucial HRD-related metabolite and propose a promising therapeutic strategy for TNBCs with low HRD scores using the combination of GDP-M, PARP inhibitors, and anti-PD-1 immunotherapy.

Secretory breast carcinoma: clinicopathological features and prognosis of 52 patients.

PURPOSE: Secretory breast carcinoma is a rare histological subtype of invasive breast cancer and considered with an indolent clinical behavior. This study was conducted to analyze the clinicopathological features of patients with secretory breast carcinoma (SBC), explore the outcome, and compare the prognostic difference with invasive ductal breast carcinoma (IDC). METHODS AND MATERIALS: Patients with SBC diagnosed between 2006 and 2017 from Fudan University Shanghai Cancer Center were included in the study, excluding patients with previous malignant tumor history and incomplete clinical data or follow-up records. Peculiar clinicopathological and immunohistochemical features of the cases were fully described. Clinical data of 4979 cases of IDC were also evaluated during this period. After propensity score matching, prognostic analysis of SBCs and IDCs was calculated by Kaplan-Meier method and landmark analysis method. RESULTS: The data of 52 patients diagnosed with SBC were identified from the pathological files. Among them, 47 patients were women, and 5 were men. The median age of the 52 SBCs was 46 years (mean, 48.1 years; range, 10-80 years). The tumor sizes ranged from 0.3 to 6.8 cm, with a mean of 3.5 cm. Eight patients (15.4%) had positive axillary lymph node involvement. The molecular classification was mostly triple-negative breast cancer (65.4%). Fluorescence in situ hybridization confirmed the presence of ETV6::NTRK3 rearrangement in 16 of 18 cases (88.9%). Furthermore, Kaplan-Meier survival analysis and landmark analysis demonstrated that there were no statistically significant differences in DFS and OS between SBC and IDC patients. CONCLUSION: Although SBCs are generally associated with a favorable prognosis, our work exhibited that the clinicopathological features of SBC were partly different from former understandings, indicating that therapeutic procedure should be prudent. Further studies are necessary to fully identify the clinical behavior and predictive markers to improve diagnosis and management in this unique subtype of breast cancer.

HER2-low heterogeneity between primary and paired recurrent/metastatic breast cancer: Implications in treatment and prognosis.

BACKGROUND: With the largest sample size to date, the authors' objective was to investigate the incidence of primary-to-metastatic human epidermal growth factor 2 (HER2) conversion and the predictors for such conversion. Moreover, no previous studies have evaluated the prognosis of patients who have negative HER2 expression (HER2-0) versus low HER2 expression (HER2-low) when HER2 status was assessed based on all recurrent/metastatic lesions. METHODS: The authors included 1299 patients who had available HER2 status of primary breast tumors and paired recurrent/metastatic lesions at Fudan University Shanghai Cancer Center and West China Hospital. RESULTS: In total, 370 patients (28.5%) experienced primary-to-metastatic HER2 conversion. Intrapatient intermetastasis spatial heterogeneity and temporal heterogeneity of HER2 were detected. When assessing HER2 based on recurrent/metastatic tumors, patients who had HER2-0 tumors had significantly shorter overall survival than those who had HER2-low tumors in the overall population and in the estrogen receptor (ER)-negative subgroup. However, when assessing HER2 based on primary tumors, there was no difference in overall survival between patients who had HER2-0 versus HER2-low tumors. Moreover, patients who had tumors that converted from HER2-0 to HER2-low had longer overall survival than those who had consistent HER2-0 status in the ER-negative subgroup. By combining four predictors (ER status, Ki67 index, biopsy site, and disease-free interval), the authors established the first prediction tool to estimate the probability of HER2-0 tumors converting to HER2-low/positive tumors. CONCLUSIONS: Intrapatient primary-to-metastatic and intermetastatic HER2 heterogeneity were observed in this large-scale cohort study. When evaluating HER2 based on recurrent/metastatic tumors, an overall survival difference was observed between patients who had HER2-0 versus HER2-low, recurrent/metastatic breast tumors. The developed prediction tool might help clinicians screen out patients with primary HER2-0 tumors that have a high probability of HER2 status conversion and recommend them for re-biopsy, thus helping to screen out candidate patients for trastuzumab deruxtecan treatment.

Comprehensive genomic profiling of breast cancers characterizes germline-somatic mutation interactions mediating therapeutic vulnerabilities.

Germline-somatic mutation interactions are universal and associated with tumorigenesis, but their role in breast cancer, especially in non-Caucasians, remains poorly characterized. We performed large-scale prospective targeted sequencing of matched tumor-blood samples from 4079 Chinese females, coupled with detailed clinical annotation, to map interactions between germline and somatic alterations. We discovered 368 pathogenic germline variants and identified 5 breast cancer DNA repair-associated genes (BCDGs; BRCA1/BRCA2/CHEK2/PALB2/TP53). BCDG mutation carriers, especially those with two-hit inactivation, demonstrated younger onset, higher tumor mutation burden, and greater clinical benefits from platinum drugs, PARP inhibitors, and immune checkpoint inhibitors. Furthermore, we leveraged a multiomics cohort to reveal that clinical benefits derived from two-hit events are associated with increased genome instability and an immune-activated tumor microenvironment. We also established an ethnicity-specific tool to predict BCDG mutation and two-hit status for genetic evaluation and therapeutic decisions. Overall, this study leveraged the large sequencing cohort of Chinese breast cancers, optimizing genomics-guided selection of DNA damaging-targeted therapy and immunotherapy within a broader population.

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.