Overcoming Endocrine Resistance in Breast Cancer

Vaccines targeting ESR1 activating mutations elicit anti-tumor immune responses and suppress estrogen signaling in therapy resistant ER+ breast cancer

ER+ breast cancers (BC) are characterized by the elevated expression and signaling of estrogen receptor alpha (ESR1), which renders them sensitive to anti-endocrine therapy. While these therapies are clinically effective, prolonged treatment inevitably results in therapeutic resistance, which can occur through the emergence of gain-of-function mutations in ESR1. The central importance of ESR1 and development of mutated forms of ESR1 suggest that vaccines targeting these proteins could potentially be effective in preventing or treating endocrine resistance. To explore the potential of this approach, we developed several recombinant vaccines encoding different mutant forms of ESR1 (ESR1mut) and validated their ability to elicit ESR1-specific T cell responses. We then developed novel ESR1mut-expressing murine mammary cancer models to test the anti-tumor potential of ESR1mut vaccines. We found that these vaccines could suppress tumor growth, ESR1mut expression and estrogen signaling in vivo. To illustrate the applicability of these findings, we utilize HPLC to demonstrate the presentation of ESR1 and ESR1mut peptides on human ER+ BC cell MHC complexes. We then show the presence of human T cells reactive to ESR1mut epitopes in an ER+ BC patient. These findings support the development of ESR1mut vaccines, which we are testing in a Phase I clinical trial.

Discovery of novel quinoline scaffold selective estrogen receptor degraders (SERDs) for treatment of ER positive breast cancer with enhanced antiproliferative bioactivity through immunogenic cell death (ICD) effects

Combination therapy proven to be an effective therapeutic approach for estrogen receptor (ER)-positive breast cancer. Currently, cyclin-dependent kinase 4/6 (CDK4/6) inhibitors are combined with aromatase inhibitors (AIs) or selective estrogen receptor degraders (SERDs) as first-line therapy for advanced ER-positive breast cancer. Herein, a new family of quinoline scaffold SERDs was synthesized and evaluated in MCF-7 cells. Among them, compounds 18j and 24d exhibited remarkable MCF-7 inhibition, both alone and in combination with ribociclib (CDK4/6 inhibitor), in vitro and in vivo. Meanwhile, compounds 18j and 24d effectively degraded ER and inhibited ER downstream signaling pathways. Interestingly, compounds 18j and 24d induced endoplasmic reticulum stress (ERS) and triggered immunogenic cell death (ICD) via damage-associated molecular patterns (DAMPs) in MCF-7 cells. These findings highlight the immune-related and enhanced antiproliferative effects of oral SERDs in ER positive breast cancer treatment.

Advances in dual-targeting inhibitors of HDAC6 for cancer treatment

Histone Deacetylase 6 (HDAC6) is an essential regulator of histone acetylation processes, exerting influence on a multitude of cellular functions such as cell motility, endocytosis, autophagy, apoptosis, and protein trafficking through its deacetylation activity. The significant implications of HDAC6 in diseases such as cancer, neurodegenerative disorders, and immune disorders have motivated extensive investigation into the development of specific inhibitors targeting this enzyme for therapeutic purposes. Single targeting drugs carry the risk of inducing drug resistance, thus prompting exploration of dual targeting therapy which offers the potential to impact multiple signaling pathways simultaneously, thereby lowering the likelihood of resistance development. While pharmacological studies have exhibited promise in combined therapy involving HDAC6, challenges related to potential drug interactions exist. In response to these challenges, researchers are investigating HDAC6 hybrid molecules which enable the concomitant targeting of HDAC6 and other key proteins, thus enhancing treatment efficacy while mitigating side effects and reducing the risk of resistance compared to traditional combination therapies. The published design strategies for dual targeting inhibitors of HDAC6 are summarized and discussed in this review. This will provide some valuable insights into more novel HDAC6 dual targeting inhibitors to meet the urgent need for innovative therapies in oncology and other related fields.

Mechanisms of sensitivity and resistance to CDK4/CDK6 inhibitors in hormone receptor-positive breast cancer treatment

Cell cycle dysregulation is a hallmark of cancer that promotes eccessive cell division. Cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6) are key molecules in the G1-to-S phase cell cycle transition and are crucial for the onset, survival, and progression of breast cancer (BC). Small-molecule CDK4/CDK6 inhibitors (CDK4/6i) block phosphorylation of tumor suppressor Rb and thus restrain susceptible BC cells in G1 phase. Three CDK4/6i are approved for the first-line treatment of patients with advanced/metastatic hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) BC in combination with endocrine therapy (ET). Though this has improved the clinical outcomes for survival of BC patients, there is no established standard next-line treatment to tackle drug resistance. Recent studies suggest that CDK4/6i can modulate other distinct effects in both BC and breast stromal compartments, which may provide new insights into aspects of their clinical activity. This review describes the biochemistry of the CDK4/6-Rb-E2F pathway in HR+ BC, then discusses how CDK4/6i can trigger other effects in BC/breast stromal compartments, and finally outlines the mechanisms of CDK4/6i resistance that have emerged in recent preclinical studies and clinical cohorts, emphasizing the impact of these findings on novel therapeutic opportunities in BC.

Adipocyte-conditioned medium induces tamoxifen resistance by activating PI3K/Akt/mTOR pathway in estrogen receptor-positive breast cancer cells

Resistance to endocrine therapy is a major clinical challenge in estrogen receptor (ER)-positive breast cancer. Obesity is associated with the clinical response to ER-positive breast cancers; however, the mechanism underlying obesity-induced resistance to endocrine therapy in ER-positive breast cancers remains unclear. In this study, we investigated the molecular mechanisms underlying obesity-induced resistance to tamoxifen (TAM), an anti-estrogen agent, in the ER-positive breast cancer cell line MCF-7 using differentiated adipocyte-conditioned medium (D-CM). Treatment of the cells with D-CM promoted TAM resistance by reducing TAM-induced apoptosis. The expression levels of the ERα target genes were higher in D-CM-treated cells than those in untreated ones. In contrast, when the cells were cultured in the presence of TAM, the expression levels were decreased, with or without D-CM. Moreover, the expression of the markers for cancer stem-like cells (CSCs) and mammosphere formation was enhanced by co-treating with D-CM and TAM, compared with TAM alone. The phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway was activated in MCF-7 cells by D-CM treatment, even in the presence of TAM. Inhibition of the PI3K/Akt/mTOR pathway decreased the expression levels of the CSC markers, suppressed mammosphere formation, and resensitized to TAM via inducing apoptosis in D-CM-treated cells. These results indicate that the conditioned medium of differentiated adipocytes promoted TAM resistance by inducing the CSC phenotype through activation of the PI3K/Akt/mTOR pathway in ER-positive breast cancer cells. Thus, the PI3K/Akt/mTOR pathway may be a therapeutic target in obese patients with ER-positive breast cancers.

Ionizable Drugs Enable Intracellular Delivery of Co-Formulated siRNA

Targeting complementary pathways in diseases such as cancer can be achieved with co-delivery of small interfering ribonucleic acid (siRNA) and small molecule drugs; however, current formulation strategies are typically limited to one, but not both. Here, ionizable small molecule drugs and siRNA are co-formulated in drug-rich nanoparticles. Ionizable analogs of the selective estrogen receptor degrader fulvestrant self-assemble into colloidal drug aggregates and cause endosomal disruption, allowing co-delivery of siRNA against a non-druggable target. siRNA is encapsulated in lipid-stabilized, drug-rich colloidal nanoparticles where the ionizable lipid used in conventional lipid nanoparticles is replaced with an ionizable fulvestrant analog. The selection of an appropriate phospholipid and formulation buffer enables endocytosis and potent reporter gene knockdown in cancer cells. Importantly, siRNA targeting cyclin E1 is effectively delivered to drug-resistant breast cancer cells, demonstrating the utility of this approach. This strategy opens the possibility of using ionizable drugs to co-deliver RNA and ultimately improve therapeutic outcomes.

OBHSA, a novel selective estrogen receptor degrader, overcomes tamoxifen resistance through cell cycle arrest and unfolded protein response-mediated apoptosis in breast cancer

Breast cancer (BC) is a highly heterogeneous tumor that has surpassed lung cancer as the most frequently diagnosed cancer in women. In clinical practice,the primary approach for treating estrogen receptor alpha (ERα)-positive BC is through endocrine therapy, which involves targeting the ERα using medications like tamoxifen and fulvestrant. However, the problem of de novo or acquired resistance poses a significant clinical challenge, emphasizing the critical need for the development of novel therapeutic strategies. In this regard, we have successfully designed and developed a novel selective estrogen receptor degrader (SERD) called OBHSA, which specifically targets and degrades ERα, demonstrating remarkable efficacy. Our findings revealed the effectiveness of OBHSA in inhibiting the proliferation of various BC cells, including both tamoxifen-sensitive and tamoxifen-resistant BC cells, indicating its great potential to overcome endocrine resistance. In terms of mechanism, we discovered that OBHSA overcame tamoxifen resistance through two distinct pathways. Firstly, OBHSA degraded cyclin D1 in an ERα-dependent manner, thereby blocking the cell cycle. Secondly, OBHSA induced an elevation in intracellular reactive oxygen species, triggering an excessive activation of the unfolded protein response (UPR) and ultimately leading to apoptotic cell death. In summary, our finding demonstrated that OBHSA exerts anti-tumor effects by inducing cell cycle arrest and UPR-mediated apoptosis. These findings hold promise for the development of novel therapeutic drugs targeting endocrine-resistant BC.

UBE2M forms a positive feedback loop with estrogen receptor to drive breast cancer progression and drug resistance

UBE2M, a NEDD8-conjugating enzyme, is dysregulated in various human cancers and promotes tumor cell proliferation. However, its role in estrogen receptor-positive (ER+) breast cancer remains unknown. We found that UBE2M expression was significantly higher in ER+ breast cancer tissues than in ER-negative (ER-) breast cancer tissues. Higher expression of UBE2M indicated a poorer prognosis in patients with ER+ breast cancer but not in those with ER- breast cancer. Of interest, a positive feedback loop was observed between UBE2M and ERα. Specifically, ERα enhanced the HIF-1α-mediated transcription of UBE2M. In turn, UBE2M maintained ERα expression by inhibiting its ubiquitination and degradation through UBE2M-CUL3/4A-E6AP-ERα axis. Functionally, silencing of UBE2M suppressed the growth of breast cancer cells by inducing cell cycle arrest and apoptosis and improved their sensitivity to fulvestrant both in vitro and in vivo. Altogether, our findings reveal that the UBE2M-ERα feedback loop drives breast cancer progression and fulvestrant resistance, suggesting UBE2M as a viable target for endocrine therapy of ER+ breast cancer.

Essential gene screening identifies the bromodomain-containing protein BRPF1 as a new actionable target for endocrine therapy-resistant breast cancers

Identifying master epigenetic factors controlling proliferation and survival of cancer cells allows to discover new molecular targets exploitable to overcome resistance to current pharmacological regimens. In breast cancer (BC), resistance to endocrine therapy (ET) arises from aberrant Estrogen Receptor alpha (ERα) signaling caused by genetic and epigenetic events still mainly unknown. Targeting key upstream components of the ERα pathway provides a way to interfere with estrogen signaling in cancer cells independently from any other downstream event. By combining computational analysis of genome-wide 'drop-out' screenings with siRNA-mediated gene knock-down (kd), we identified a set of essential genes in luminal-like, ERα + BC that includes BRPF1, encoding a bromodomain-containing protein belonging to a family of epigenetic readers that act as chromatin remodelers to control gene transcription. To gather mechanistic insights into the role of BRPF1 in BC and ERα signaling, we applied chromatin and transcriptome profiling, gene ablation and targeted pharmacological inhibition coupled to cellular and functional assays. Results indicate that BRPF1 associates with ERα onto BC cell chromatin and its blockade inhibits cell cycle progression, reduces cell proliferation and mediates transcriptome changes through the modulation of chromatin accessibility. This effect is elicited by a widespread inhibition of estrogen signaling, consequent to ERα gene silencing, in antiestrogen (AE) -sensitive and -resistant BC cells and pre-clinical patient-derived models (PDOs). Characterization of the functional interplay of BRPF1 with ERα reveals a new regulator of estrogen-responsive BC cell survival and suggests that this epigenetic factor is a potential new target for treatment of these tumors.

Integrative radiomics clustering analysis to decipher breast cancer heterogeneity and prognostic indicators through multiparametric MRI

Breast cancer diagnosis and treatment have been revolutionized by multiparametric Magnetic Resonance Imaging (mpMRI), encompassing T2-weighted imaging (T2WI), Diffusion-weighted imaging (DWI), and Dynamic Contrast-Enhanced MRI (DCE-MRI). We conducted a retrospective analysis of mpMRI data from 194 breast cancer patients (September 2019 to October 2023). Using 'pyradiomics' for radiomics feature extraction and MOVICS for unsupervised clustering. Interestingly, we identified two distinct patient clusters associated with significant differences in molecular subtypes, particularly in Luminal A subtype distribution (p = 0.03), estrogen receptor (ER) (p = 0.01), progesterone receptor (PR) (p = 0.04), mean tumor size (p < 0.01), lymph node metastasis (LNM) (p = 0.01), and edema (p < 0.01). Our study emphasizes mpMRI's potential in breast cancer by using radiomics-based cluster analysis to categorize tumors, uncovering heterogeneity, and aiding in personalized treatment strategies.

Kuwanon C inhibits proliferation and induction of apoptosis via the intrinsic pathway in MDA-MB231 and T47D breast cancer cells

Breast cancer ranks as the most prevalent malignancy, presenting persistent therapeutic challenges encompassing issues such as drug resistance, recurrent occurrences, and metastatic progression. Therefore, there is a need for targeted drugs that are less toxic and more effective against breast cancer. Kuwanon C, an isoamylated flavonoid derived from mulberry resources, has shown promise as a potential candidate due to its strong cytotoxicity against cancer cells. The present study focused on investigating the anticancer activity of kuwanon C in two human breast cancer cell lines, MDA-MB231 and T47D cells. MTS assay results indicated a decrease in cell proliferation with increasing concentrations of kuwanon C. Furthermore, kuwanon C upregulated the expression levels of the cyclin-dependent kinase inhibitor p21 and effectively inhibited cell DNA replication and induced DNA damage. Flow cytometry confirmed that kuwanon C induced cell apoptosis and upregulated the expression levels of pro-apoptotic proteins (Bax and c-caspase3). Additionally, it stimulated the production of reactive oxygen species (ROS) in the cells. Transmission electron microscopy and Fluo-4 AM-calcium ion staining experiments provided insights into the endoplasmic reticulum (ER), revealing that kuwanon C induced ER stress. Kuwanon C upregulated the expression levels of unfolded protein response-related proteins (ATF4, GADD34, HSPA5, and DDIT3). Overall, the present findings suggested that kuwanon C exerts a potent inhibitory effect on breast cancer cell proliferation through modulating of the p21, induction of mitochondrial-mediated apoptosis, activation of ER stress and induction of DNA damage. These results position kuwanon C as a potential targeted therapeutic agent for breast cancer.

Integrative analyses identified gap junction beta-2 as a prognostic biomarker and therapeutic target for breast cancer

Background

Increasing evidence has shown that connexins are involved in the regulation of tumor development, immune escape, and drug resistance. This study investigated the gene expression patterns, prognostic values, and potential mechanisms of connexins in breast cancer.

Methods

We conducted a comprehensive analysis of connexins using public gene and protein expression databases and clinical samples from our institution. Connexin mRNA expressions in breast cancer and matched normal tissues were compared, and multiomics studies were performed.

Results

Gap junction beta-2 mRNA was overexpressed in breast cancers of different pathological types and molecular subtypes, and its high expression was associated with poor prognosis. The tumor membrane of the gap junction beta-2 mutated group was positive, and the corresponding protein was expressed. Somatic mutation and copy number variation of gap junction beta-2 are rare in breast cancer. The gap junction beta-2 transcription level in the p110α subunit of the phosphoinositide 3-kinase mutant subgroup was higher than that in the wild-type subgroup. Gap junction beta-2 was associated with the phosphoinositide 3-kinase-Akt signaling pathway, extracellular matrix-receptor interaction, focal adhesion, and proteoglycans in cancer. Furthermore, gap junction beta-2 overexpression may be associated with phosphoinositide 3-kinase and histone deacetylase inhibitor resistance, and its expression level correlated with infiltrating CD8+ T cells, macrophages, neutrophils, and dendritic cells.

Conclusions

Gap junction beta-2 may be a promising therapeutic target for targeted therapy and immunotherapy and may be used to predict breast cancer prognosis.

Everolimus plus endocrine therapy beyond CDK4/6 inhibitors progression for HR+ /HER2- advanced breast cancer: a real-world evidence cohort

PURPOSE

Everolimus in combination with endocrine therapy (ET) was formerly approved as 2nd-line therapy in HR(+)/HER2(-) advanced breast cancer (aBC) patients (pts) progressing during or after a non-steroidal aromatase inhibitor (NSAI). Since this approval, the treatment landscape of aBC has changed dramatically, particularly with the arrival of CDK 4-6 inhibitors. Endocrine monotherapy after progression to CDK4/6 inhibitors has shown a limited progression-free survival (PFS), below 3 months. Evidence of the efficacy of everolimus plus ET after CDK4/6 inhibitors is scarce.

METHODS

A retrospective observational study of patients with aBC treated with everolimus and ET beyond CDK4/6-i progression compiled from February 2015 to December 2022 in 4 Spanish hospitals was performed. Clinical and demographic data were collected from medical records. The main objective was to estimate the median progression-free survival (mPFS). Everolimus adverse events (AE) were registered. Quantitative variables were summarized with medians; qualitative variables with proportions and the Kaplan-Meier method were used for survival estimates.

RESULTS

One hundred sixty-one patients received everolimus plus ET (exemestane: 96, fulvestrant: 54, tamoxifen: 10, unknown: 1) after progressing on a CDK4/6 inhibitor. The median follow-up time was 15 months (interquartile range: 1-56 months). The median age at diagnosis was 49 years (range: 35-90 years). The estimated mPFS was 6.0 months (95%CI 5.3-7.8 months). PFS was longer in patients with previous CDK4/6 inhibitor therapy lasting for > 18 months (8.7 months, 95%CI 6.6-11.3 months), in patients w/o visceral metastases (8.0 months, 95%CI 5.8-10.5 months), and chemotherapy-naïve in the metastatic setting (7.2 months, 95%CI 5.9-8.4 months).

CONCLUSION

This retrospective analysis cohort of everolimus plus ET in mBC patients previously treated with a CDK4/6 inhibitor suggests a longer estimated mPFS when compared with the mPFS with ET monotherapy obtained from current randomized clinical data. Everolimus plus ET may be considered as a valid control arm in novel clinical trial designs.

Ginsenoside Rg3 combined with near-infrared photothermal reversal of multidrug resistance in breast cancer MCF-7/ADR cells

Adriamycin (ADR) is a frequently employed chemotherapeutic agent for the management of breast cancer. Nevertheless, multidrug resistance (MDR) can impair its therapeutic efficacy in breast cancer. MDR is characterized by increased expression of the P-glycoprotein (P-gp) efflux pump, up-regulation of anti-apoptotic proteins, and downregulation of pro-apoptotic proteins. Consequently, inhibition of ATP-binding cassette (ABC) transporter proteins has been deemed the most efficacious approach to overcome MDR. In this study, we used MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide), Western blots, flow cytometry, immunofluorescence, and constructed xenograft tumors to investigate whether ginsenoside Rg3-near-infrared photothermal (Rg3-NIR) combination reversed multidrug resistance in MCF-7/ADR breast cancer. In vivo and in vitro experiments, the results showed that Rg3-NIR co-treatment was effective in inducing the apoptosis of MCF-7/ADR breast cancer cells. This was achieved by reversing the expression of drug resistance-associated proteins, while also inhibiting cell proliferation, migration, and epithelial-mesenchymal transition (EMT) processes via attenuation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway transduction. Ginsenoside Rg3 combined with near-infrared photothermal therapy (NIR) effectively reverses multidrug resistance in breast cancer MCF-7/ADR cells, providing a new therapeutic strategy for breast cancer drug resistance.

CDK9 targeting PROTAC L055 inhibits ERα-positive breast cancer

Breast cancer is one of the most prevalent malignancies affecting women worldwide, underscoring the urgent need for more effective and specific treatments. Proteolysis-targeting chimeras (PROTACs) have emerged as a promising strategy to develop new lead compounds by selectively targeting oncoproteins for degradation. In this study, we designed, synthesized and evaluated a CRBN-based PROTAC, L055, which targets CDK9. Our findings demonstrate that L055 effectively inhibits the proliferation, induces cell cycle arrest, and decreases the survival of ERα-positive breast cancer cells in vitro. L055 specifically binds to CDK9, facilitating its degradation via the CRBN-dependent proteasomal pathway. Additionally, L055 suppressed the growth of organoids and tumors derived from T47D and MCF7 cells in nude mice. Thus, L055 represents a potential novel therapeutic agent for ERα-positive breast cancer and potentially other malignancies.

The emerging role of targeted protein degradation to treat and study cancer

The evolution of cancer treatment has provided increasingly targeted strategies both in the upfront and relapsed disease settings. Small-molecule inhibitors and immunotherapy have risen to prominence with chimeric antigen receptor T-cells, checkpoint inhibitors, kinase inhibitors, and monoclonal antibody therapies being deployed across a range of solid organ and haematological malignancies. However, novel approaches are required to target transcription factors and oncogenic fusion proteins that are central to cancer biology and have generally eluded successful drug development. Thalidomide analogues causing protein degradation have been a cornerstone of treatment in multiple myeloma, but a lack of in-depth mechanistic understanding initially limited progress in the field. When the protein cereblon (CRBN) was found to mediate thalidomide analogues' action and CRBN's neo-targets were identified, existing and novel drug development accelerated, with applications outside multiple myeloma, including non-Hodgkin's lymphoma, myelodysplastic syndrome, and acute leukaemias. Critically, transcription factors were the first canonical targets described. In addition to broadening the application of protein-degrading drugs, resistance mechanisms are being overcome and targeted protein degradation is widening the scope of druggable proteins against which existing approaches have been ineffective. Examples of targeted protein degraders include molecular glues and proteolysis targeting chimeras (PROTACs): heterobifunctional molecules that bind to proteins of interest and cause proximity-induced ubiquitination and proteasomal degradation via a linked E3 ligase. Twenty years since their inception, PROTACs have begun progressing through clinical trials, with early success in targeting the oestrogen receptor and androgen receptor in breast and prostate cancer respectively. This review explores important developments in targeted protein degradation to both treat and study cancer. It also considers the potential advantages and challenges in the translational aspects of developing new treatments. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Prediction of breast cancer and axillary positive-node response to neoadjuvant chemotherapy based on multi-parametric magnetic resonance imaging radiomics models

PURPOSE

Accurate identification of primary breast cancer and axillary positive-node response to neoadjuvant chemotherapy (NAC) is important for determining appropriate surgery strategies. We aimed to develop combining models based on breast multi-parametric magnetic resonance imaging and clinicopathologic characteristics for predicting therapeutic response of primary tumor and axillary positive-node prior to treatment.

MATERIALS AND METHODS

A total of 268 breast cancer patients who completed NAC and underwent surgery were enrolled. Radiomics features and clinicopathologic characteristics were analyzed through the analysis of variance and the least absolute shrinkage and selection operator algorithm. Finally, 24 and 28 optimal features were selected to construct machine learning models based on 6 algorithms for predicting each clinical outcome, respectively. The diagnostic performances of models were evaluated in the testing set by the area under the curve (AUC), sensitivity, specificity, and accuracy.

RESULTS

Of the 268 patients, 94 (35.1 %) achieved breast cancer pathological complete response (bpCR) and of the 240 patients with clinical positive-node, 120 (50.0 %) achieved axillary lymph node pathological complete response (apCR). The multi-layer perception (MLP) algorithm yielded the best diagnostic performances in predicting apCR with an AUC of 0.825 (95 % CI, 0.764-0.886) and an accuracy of 77.1 %. And MLP also outperformed other models in predicting bpCR with an AUC of 0.852 (95 % CI, 0.798-0.906) and an accuracy of 81.3 %.

CONCLUSIONS

Our study established non-invasive combining models to predict the therapeutic response of primary breast cancer and axillary positive-node prior to NAC, which may help to modify preoperative treatment and determine post-NAC surgery strategy.

Initial ribociclib plus endocrine therapy for HR+/HER2- advanced breast cancer in pre- and postmenopausal Chinese women: Primary results from a phase 2 randomized study

Background

The MONALEESA‐7 and ‐2 phase 3 randomized trials demonstrated a statistically significant progression‐free survival (PFS) and overall survival (OS) benefit with initial ribociclib + endocrine therapy (ET) versus placebo + ET in pre‐ and postmenopausal patients with hormone receptor–positive (HR+)/human epidermal growth factor receptor 2–negative (HER2−) advanced breast cancer (ABC), respectively. Similar trends were observed in Asian subgroup analyses. This phase 2 bridging study of initial ET + ribociclib enrolled pre‐ and postmenopausal patients with HR+/HER2– ABC from China and was conducted to demonstrate consistency of PFS results in a Chinese population relative to the global MONALEESA‐7 and ‐2 studies.

Methods

Patients were randomized (1:1) to ET (nonsteroidal aromatase inhibitor + goserelin for premenopausal patients; letrozole for postmenopausal patients) + either ribociclib or placebo. The primary endpoint was investigator‐assessed PFS.

Results

As of April 25, 2022, the median follow‐up was 34.7 months in both cohorts. In the premenopausal cohort, median PFS was 27.6 months in the ribociclib arm (n = 79) versus 14.7 months in the placebo arm (n = 77) (hazard ratio 0.67 [95% CI: 0.45, 1.01]). In the postmenopausal cohort, median PFS was not reached in the ribociclib arm versus 18.5 months in the placebo arm (n = 77 in each arm) (hazard ratio 0.40 [95% CI: 0.26, 0.62]). Data also suggested improvements in secondary efficacy endpoints, although OS data were not mature. The safety profile in this population was consistent with that in global studies.

Conclusions

These data demonstrate a favorable benefit–risk profile for ribociclib + ET in Chinese patients.

Investigation of the causal relationship between breast cancer and thyroid cancer: a set of two-sample bidirectional Mendelian randomization study

PURPOSE

A potential association between breast (BC) and thyroid cancer (TC) has been observed. We investigated if the relationship between BC and TC is causal using bidirectional Mendelian randomization (MR) in Asian and European populations.

METHODS

BC-linked single nucleotide polymorphisms (SNPs) were acquired from a genome-wide association study (GWAS) conducted by the Breast Cancer Association Consortium and Biobank Japan. The most recent TC GWAS data were obtained from the FinnGen Project and National Biobank of Korea. We assessed the potential causal relationship between BC and TC using various MR methods, including inverse-variance-weighting (IVW). Sensitivity, heterogeneity, and pleiotropic tests were performed to assess reliability.

RESULTS

We found a bidirectional causal association between BC and TC within Europeans (IVW, TC on BC: odds ratio [OR] 1.090, 95% confidence interval [CI]: 1.012-1.173, P = 0.023; BC on TC: OR 1.265, 95% CI: 1.158-1.381, P < 0.001). A one-way causal relationship between BC susceptibility and TC risk was found in Asians (IVW BC on TC: OR 2.274, 95% CI: 2.089-2.475, P < 0.001). Subsequently, we identified a noteworthy bidirectional causal relationship between estrogen receptor (ER)-positive BC and TC (IVW, TC on ER-positive BC: OR 1.104, 95% CI: 1.001-1.212, P = 0.038; ER-positive BC on TC: OR 1.223, 95%CI: 1.072-1.395, P = 0.003), but not ER-negative BC and TC in Europeans.

CONCLUSION

We revealed a reciprocal causal association between ER-positive BC and TC. These findings establish a theoretical framework for the simultaneous surveillance and treatment of BC and TC.

Inactivated cGAS-STING Signaling Facilitates Endocrine Resistance by Forming a Positive Feedback Loop with AKT Kinase in ER+HER2- Breast Cancer

Endocrine-resistant ER+HER2- breast cancer (BC) is particularly aggressive and leads to poor clinical outcomes. Effective therapeutic strategies against endocrine-resistant BC remain elusive. Here, analysis of the RNA-sequencing data from ER+HER2- BC patients receiving neoadjuvant endocrine therapy and spatial transcriptomics analysis both show the downregulation of innate immune signaling sensing cytosolic DNA, which primarily occurs in endocrine-resistant BC cells, not immune cells. Indeed, compared with endocrine-sensitive BC cells, the activity of sensing cytosolic DNA through the cGAS-STING pathway is attenuated in endocrine-resistant BC cells. Screening of kinase inhibitor library show that this effect is mainly mediated by hyperactivation of AKT1 kinase, which binds to kinase domain of TBK1, preventing the formation of a trimeric complex TBK1/STING/IRF3. Notably, inactivation of cGAS-STING signaling forms a positive feedback loop with hyperactivated AKT1 to promote endocrine resistance, which is physiologically important and clinically relevant in patients with ER+HER2- BC. Blocking the positive feedback loop using the combination of an AKT1 inhibitor with a STING agonist results in the engagement of innate and adaptive immune signaling and impairs the growth of endocrine-resistant tumors in humanized mice models, providing a potential strategy for treating patients with endocrine-resistant BC.

Strategy of combining CDK4/6 inhibitors with other therapies and mechanisms of resistance

Cell cycle-dependent protein kinase 4/6 (CDK4/6) is a crucial kinase that regulates the cell cycle, essential for cell division and proliferation. Hence, combining CDK4/6 inhibitors with other anti-tumor drugs is a pivotal clinical strategy. This strategy can efficiently inhibit the growth and division of tumor cells, reduce the side effects, and improve the quality of life of patients by reducing the dosage of combined anticancer drugs. Furthermore, the combination therapy strategy of CDK4/6 inhibitors could ameliorate the drug resistance of combined drugs and overcome the CDK4/6 resistance caused by CDK4/6 inhibitors. Various tumor treatment strategies combined with CDK4/6 inhibitors have entered the clinical trial stage, demonstrating their substantial clinical potential. This study reviews the research progress of CDK4/6 inhibitors from 2018 to 2022, the related resistance mechanism of CDK4/6 inhibitors, and the strategy of combination medication.

Structure-Activity Relationship Study of Tris-Benzamides as Estrogen Receptor Coregulator Binding Modulators

Estrogen receptor coregulator binding modulators (ERXs) are a novel class of molecules targeting the interaction between estrogen receptor α (ERα) and its coregulator proteins, which has proven to be an attractive strategy for overcoming endocrine resistance in breast cancer. We previously reported ERX-11, an orally bioavailable tris-benzamide, that demonstrated promising antitumor activity against ERα-positive breast cancer cells. To comprehend the significance of the substituents in ERX-11, we carried out structure-activity relationship studies. In addition, we introduced additional alkyl substituents at either the N- or C-terminus to improve binding affinity and biological activity. Further optimization guided by conformational restriction led to the identification of a trans-4-phenylcyclcohexyl group at the C-terminus (18h), resulting in a greater than 10-fold increase in binding affinity and cell growth inhibition potency compared to ERX-11. Tris-benzamide 18h disrupted the ERα-coregulator interaction and inhibited the ERα-mediated transcriptional activity. It demonstrated strong antiproliferative activity on ERα-positive breast cancer cells both in vitro and in vivo, offering a promising potential as a therapeutic candidate for treating ERα-positive breast cancer.

Resistance to FOXM1 inhibitors in breast cancer is accompanied by impeding ferroptosis and apoptotic cell death

PURPOSE

Cancer treatments often become ineffective because of acquired drug resistance. To characterize changes in breast cancer cells accompanying development of resistance to inhibitors of the oncogenic transcription factor, FOXM1, we investigated the suppression of cell death pathways, especially ferroptosis, in FOXM1 inhibitor-resistant cells. We also explored whether ferroptosis activators can synergize with FOXM1 inhibitors and can overcome FOXM1 inhibitor resistance.

METHODS

In estrogen receptor-positive and triple-negative breast cancer cells treated with FOXM1 inhibitor NB73 and ferroptosis activators dihydroartemisinin and JKE1674, alone and in combination, we measured suppression of cell viability, motility, and colony formation, and monitored changes in gene and protein pathway expressions and mitochondrial integrity.

RESULTS

Growth suppression of breast cancer cells by FOXM1 inhibitors is accompanied by increased cell death and alterations in mitochondrial morphology and metabolic activity. Low doses of FOXM1 inhibitor strongly synergize with ferroptosis inducers to reduce cell viability, migration, colony formation, and expression of proliferation-related genes, and increase intracellular Fe+2 and lipid peroxidation, markers of ferroptosis. Acquired resistance to FOXM1 inhibition is associated with increased expression of cancer stem-cell markers and proteins that repress ferroptosis, enabling cell survival and drug resistance. Notably, resistant cells are still sensitive to growth suppression by low doses of ferroptosis activators, effectively overcoming the acquired resistance.

CONCLUSION

Delineating changes in viability and cell death pathways that can overcome drug resistance should be helpful in determining approaches that might best prevent or reverse resistance to therapeutic targeting of FOXM1 and ultimately improve patient clinical outcomes.

EstroGene2.0: A multi-omic database of response to estrogens, ER-modulators, and resistance to endocrine therapies in breast cancer

Endocrine therapies targeting the estrogen receptor (ER/ESR1) are the cornerstone to treat ER-positive breast cancers patients, but resistance often limits their effectiveness. Understanding the molecular mechanisms is thus key to optimize the existing drugs and to develop new ER-modulators. Notable progress has been made although the fragmented way data is reported has reduced their potential impact. Here, we introduce EstroGene2.0, an expanded database of its precursor 1.0 version. EstroGene2.0 focusses on response and resistance to endocrine therapies in breast cancer models. Incorporating multi-omic profiling of 361 experiments from 212 studies across 28 cell lines, a user-friendly browser offers comprehensive data visualization and metadata mining capabilities (https://estrogeneii.web.app/). Taking advantage of the harmonized data collection, our follow-up meta-analysis revealed substantial diversity in response to different classes of ER-modulators including SERMs, SERDs, SERCA and LDD/PROTAC. Notably, endocrine resistant models exhibit a spectrum of transcriptomic alterations including a contra-directional shift in ER and interferon signaling, which is recapitulated clinically. Furthermore, dissecting multiple ESR1-mutant cell models revealed the different clinical relevance of genome-edited versus ectopic overexpression model engineering and identified high-confidence mutant-ER targets, such as NPY1R. These examples demonstrate how EstroGene2.0 helps investigate breast cancer's response to endocrine therapies and explore resistance mechanisms.

Targeting estrogen mediated CYP4F2/CYP4F11-20-HETE metabolic disorder decelerates tumorigenesis in ER+ breast cancer

Purpose

As the most common subset of breast cancer (BC), estrogen receptor positive (ER+) BC accounting for 80% of cases, has become a global public health concern. The female hormone estrogen (E2) unequivocally drives ER + breast malignancies. The reasons that estrogen affects BC development has long been considered, yet further study remains to be conducted of the molecular events in the E2-estrogen receptor α (ERα) signaling pathway in ER + BC progression, especially lipid metabolism, so providing more options for tailored and individualized therapy. Our aim is to find out new targets and clinical biomarkers for ER + breast cancer treatment from the perspective of lipid metabolism.

Methods

Lipid metabolomics profiling was used to examine the membrane phospholipid stimulated by E2. Clinical BC samples were used to assess the association of CYP4F2, CYP4F11 expression with clinicopathological characteristics and patient outcomes. Some inhibitors of main enzymes in AA metabolism were used combined with E2 to assess roles of CYP4F2/CYP4F11 in the progression of ER + BC. CYP4F2, CYP4F11 overexpression and knockdown BC cell lines were employed to examine the effects of CYP4F2, CYP4F11 on cellular proliferation, apoptosis and tumor growth. Western blotting, qPCR, Immunohistochemical staining and flow cytometry were also conducted to determine the underlying mechanisms related to CYP4F2, CYP4F11 function.

Results

The activation of the CYP450 signaling pathway in arachidonic acid metabolism contributed to ER + BC tumorigenesis. In ER + BC, CYP4F2 and CYP4F11 overexpression induced by E2 could promote cancer cell proliferation and resistance to apoptosis by producing the metabolite 20-HETE and activating the antiapoptotic protein Bcl-2. CYP4F2 and CYP4F11 elevation correlates with poorer overall survival and disease-free survival in ER + BC patients.

Conclusion

CYP4F2, CYP4F11 and their metabolite 20-HETE could serve as effective prognostic markers and attractive therapeutic targets for novel anticancer drug development about ER + BC.

Cytokines-activated nuclear IKKα-FAT10 pathway induces breast cancer tamoxifen-resistance

Endocrine therapy that blocks estrogen signaling is the most effective treatment for patients with estrogen receptor positive (ER+) breast cancer. However, the efficacy of agents such as tamoxifen (Tam) is often compromised by the development of resistance. Here we report that cytokines-activated nuclear IKKα confers Tam resistance to ER+ breast cancer by inducing the expression of FAT10, and that the expression of FAT10 and nuclear IKKα in primary ER+ human breast cancer was correlated with lymphotoxin β (LTB) expression and significantly associated with relapse and metastasis in patients treated with adjuvant mono-Tam. IKKα activation or enforced FAT10 expression promotes Tam-resistance while loss of IKKα or FAT10 augments Tam sensitivity. The induction of FAT10 by IKKα is mediated by the transcription factor Pax5, and coordinated via an IKKα-p53-miR-23a circuit in which activation of IKKα attenuates p53-directed repression of FAT10. Thus, our findings establish IKKα-to-FAT10 pathway as a new therapeutic target for the treatment of Tam-resistant ER+ breast cancer.

Clinical efficacy of CDK4/6 inhibitor plus endocrine therapy in HR-positive/HER2-0 and HER2-low-positive metastatic breast cancer: a secondary analysis of PALOMA-2 and PALOMA-3 trials

BACKGROUND

Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors in combination with traditional endocrine therapy (ET) are now the recommended first-line treatment for hormone receptor (HR)-positive and HER2-negative metastatic breast cancer (MBC). However, the benefits of adding CDK4/6 inhibitors to ET in HER2-low-positive and HER2-0 subgroups remain unclear. We aimed to assess the effectiveness of CDK4/6 inhibitors in combination with ET in patients with HR-positive, HER2-low-positive and HER2-0 MBC.

METHODS

This secondary analysis assessed progression-free survival (PFS) among HER2-low-positive and HER2-0 patients enrolled in the double-blind, placebo-controlled randomised clinical trials PALOMA-2 and PALOMA-3. The study included 1186 HER2-negative, HR-positive female patients, with available immunohistochemistry (IHC) and/or in situ hybridization (ISH) results, across 17 countries enrolled between February 2013 and August 2014. HER2-low-positive status was defined by IHC 1+ or 2+ with negative ISH, and HER2-zero by IHC 0. Data analyses were conducted between March and May 2023. In the PALOMA-2 trial, patients were randomly assigned to receive either palbociclib or placebo, in combination with letrozole in the first-line treatment for HR-positive MBC. Patients in the PALOMA-3 study, who had progression or relapse during previous ET, were randomly allocated to receive either palbociclib plus fulvestrant or placebo plus fulvestrant. The primary endpoint was investigator-assessed PFS. Kaplan-Meier approach and Cox proportional hazards model were applied to estimate the association of treatment strategies with PFS among HER2-0 and HER2-low-positive populations. The two trials are registered with ClinicalTrials.gov, number NCT01740427 and NCT01942135.

FINDINGS

Of the 666 patients with MBC from the PALOMA-2 study, there were 153 HER2-0 and 513 HER2-low-positive patients. In the HER2-0 population, no significant difference in PFS was observed between the palbociclib-letrozole and placebo-letrozole groups (hazard ratio = 0.79, 95% confidence interval [CI] 0.48-1.30, p = 0.34). In the HER2-low-positive population, palbociclib-letrozole demonstrated a significantly lower risk of PFS than placebo-letrozole group (hazard ratio = 0.52, 95% CI 0.41-0.66, p < 0.0001). The PALOMA-3 study analysed 520 patients with MBC. Within the 153 HER2-0 patients, the palbociclib-fulvestrant group showed a significantly longer PFS than the placebo-fulvestrant group (hazard ratio = 0.54, 95% CI 0.30-0.95, p = 0.034). Among the 367 HER2-low-positive patients, palbociclib-fulvestrant improved PFS (hazard ratio = 0.39, 95% CI 0.28-0.54, p < 0.0001).

INTERPRETATION

The combination of a CDK4/6 inhibitor with ET significantly improved PFS in HER2-low-positive patients, while for HER2-0 patients, benefits were primarily observed in patients who had progressed on previous ET. Furthermore, HER2-0 patients may derive limited benefits from first-line CDK4/6 inhibitor treatment. Further work is needed to validate these findings and to delineate patient subsets that are most likely to benefit from the combination of CDK4/6 inhibitors and ET as first-line treatments.

FUNDING

None.

Circulating tumour DNA dynamics during alternating chemotherapy and hormonal therapy in metastatic breast cancer: the ALERT study

PURPOSE

Although changes in circulating tumour DNA (ctDNA) in breast cancer are well described, the kinetics of their fluctuations has not been described over short timescales. We investigated ctDNA dynamics during alternating cycles of chemotherapy and hormonal treatment in pre-treated patients with oestrogen receptor-positive metastatic breast cancer.

METHODS

Patients received alternating, 9-week cycles of eribulin and aromatase inhibitors (AIs). The clinical primary endpoint, progression-free survival (PFS), was monitored at 3, 6 and 9 months; secondary endpoints, clinical benefit rate (CBR), safety and tolerability profiles, were also assessed. Importantly, ctDNA fluctuations were monitored using the Oncomine™ Breast cfDNA assay to test whether biomarkers may change rapidly between chemotherapy and aromatase inhibitor (AI) treatment in the setting of advanced breast cancer, potentially reflecting disease dynamics.

RESULTS

The median PFS was 202 days (95% CI: 135-undefined) and 235 days (95% CI: 235-undefined) at 6 and 9 months, respectively, with a 50% CBR at both 6 and 9 months. Dynamic changes in ctDNA were observed in short timescales between chemotherapy and AI treatment and support the clinical benefit (CB) seen in individual patients and, critically, appear informative of acquired resistance in real time.

CONCLUSION

Changes in ctDNA can occur rapidly and reflect changes in patients' clinical tumour responses (NCT02681523).

MICAL-L2, as an estrogen-responsive gene, is involved in ER-positive breast cancer cell progression and tamoxifen sensitivity via the AKT/mTOR pathway

Endocrine treatment, particularly tamoxifen, has shown significant improvement in the prognosis of patients with estrogen receptor-positive (ER-positive) breast cancer. However, the clinical utility of this treatment is often hindered by the development of endocrine resistance. Therefore, a comprehensive understanding of the underlying mechanisms driving ER-positive breast cancer carcinogenesis and endocrine resistance is crucial to overcome this clinical challenge. In this study, we investigated the expression of MICAL-L2 in ER-positive breast cancer and its impact on patient prognosis. We observed a significant upregulation of MICAL-L2 expression in ER-positive breast cancer, which correlated with a poorer prognosis in these patients. Furthermore, we found that estrogen-ERβ signaling promoted the expression of MICAL-L2. Functionally, our study demonstrated that MICAL-L2 not only played an oncogenic role in ER-positive breast cancer tumorigenesis but also influenced the sensitivity of ER-positive breast cancer cells to tamoxifen. Mechanistically, as an estrogen-responsive gene, MICAL-L2 facilitated the activation of the AKT/mTOR signaling pathway in ER-positive breast cancer cells. Collectively, our findings suggest that MICAL-L2 could serve as a potential prognostic marker for ER-positive breast cancer and represent a promising molecular target for improving endocrine treatment and developing therapeutic approaches for this subtype of breast cancer.

PFKFB3 regulates breast cancer tumorigenesis and Fulvestrant sensitivity by affecting ERα stability

Estrogen receptor alpha (ERα) is expressed in approximately 70% of breast cancer cases and determines the sensitivity and effectiveness of endocrine therapy. 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase3 (PFKFB3) is a glycolytic enzyme that is highly expressed in a great many human tumors, and recent studies have shown that it plays a significant role in improving drug sensitivity. However, the role of PFKFB3 in regulating ERα expression and the underlying mechanism remains unclear. Here, we find by using immunohistochemistry (IHC) that PFKFB3 is elevated in ER-positive breast cancer and high expression of PFKFB3 resulted in a worse prognosis. In vitro and in vivo experiments verify that PFKFB3 promotes ER-positive breast cancer cell proliferation. The overexpression of PFKFB3 promotes the estrogen-independent ER-positive breast cancer growth. In an estrogen-free condition, RNA-sequencing data from MCF7 cells treated with siPFKFB3 showed enrichment of the estrogen signaling pathway, and a luciferase assay demonstrated that knockdown of PFKFB3 inhibited the ERα transcriptional activity. Mechanistically, down-regulation of PFKFB3 promotes STUB1 binding to ERα, which accelerates ERα degradation by K48-based ubiquitin linkage. Finally, growth of ER-positive breast cancer cells in vivo was more potently inhibited by fulvestrant combined with the PFKFB3 inhibitor PFK158 than for each drug alone. In conclusion, these data suggest that PFKFB3 is identified as an adverse prognosis factor for ER-positive breast cancer and plays a previously unrecognized role in the regulation of ERα stability and activity. Our results further explores an effective approach to improve fulvestrant sensitivity through the early combination with a PFKFB3 inhibitor.

Citrus polymethoxyflavones degrade estrogen receptor-alpha (ERα) and combine with tamoxifen for the treatment of estrogen receptor-positive breast cancer

Estrogen receptor-positive (ER+) breast cancer seriously endangers the women's physical and mental health worldwide and ER targeting therapy is vital. Here, we found that a citrus polymethoxyflavones (PMFs)-rich hydrolysate (C-H) and its major components (nobiletin and 3-methoxynobiletin) potently degrade ERα protein via the ubiquitin-proteasome pathway, thereby impairing the proliferation of ER+ breast cancer cells. Moreover, our study exhibited that C-H combined with tamoxifen (TAM) inhibited the cell proliferation of ER+ breast cancer in vitro. It was further confirmed that C-H decreased tumor growth of ER+ breast cancer in tumor-bearing 129 mice in vivo and improved the efficacy of tamoxifen. Our study revealed that the citrus PMFs have potential applications as pharmaceutical and healthcare products in breast cancer treatment by targeting ERα protein degradation.

Functional combination of resveratrol and tamoxifen to overcome tamoxifen-resistance in breast cancer cells

Researchers are encountering challenges in addressing the issue of cancer cells becoming unresponsive to various chemotherapy treatments due to drug resistance. This study was designed to study the influence of antioxidant resveratrol (RSV) to sensitize resistant breast cancer (BC) cells toward tamoxifen (TAM). The cytotoxic effects of RSV and TAM against TAM-resistant LCC2 cells and their parental michigan cancer foundation-7 BC cells were determined by sulphorhodamine B assay. Further, the expression levels of multidrug resistance (MDR) genes including ABCB1, ABCC2, ABCG2, and MRP1 using quantitative polymerase chain reaction, apoptosis induction, and reactive oxygen species (ROS) content using flow cytometry were evaluated in either LCC2 cells treated with RSV, TAM, or their combination. The obtained results showed that resistant cells have a magnificent level of MDR genes. This elevated expression dramatically lowered upon receiving the combined therapy of RSV and TAM. Additionally, our work assessed the possible role of RSV in modulating the expression of MDR genes by controlling the expression of certain microRNAs (miRNAs) that target ATP-binding cassette (ABC) transporters. According to the obtained data, the TAM and RSV combination increased the expression of tumor inhibitor miRNAs such miR-10b-3p, miR-195-3p, and miR-223-3p, which made LCC2 cells more sensitive to TAM. Furthermore, this combination showed an elevation in apoptotic levels and total ROS content. The combination between RSV and TAM could be a functional therapy in the fight against TAM-resistant BC cells via modulating miRNA and ABC transporters.

Loss of Hormone Receptor Expression after Exposure to Fluid Shear Stress in Breast Cancer Cell Lines

Following metastatic spread, many hormone receptor positive (HR+) patients develop a more aggressive phenotype with an observed loss of the HRs estrogen receptor (ER) and progesterone receptor (PR). During metastasis, breast cancer cells are exposed to high magnitudes of fluid shear stress (FSS). Unfortunately, the role for FSS on the regulation of HR expression and function during metastasis is not fully understood. This study was designed to elucidate the impact of FSS on HR+ breast cancer. Utilizing a microfluidic platform capable of exposing breast cancer cells to FSS that mimics in situ conditions, we demonstrate the impact of FSS exposure on representative HR+ breast cancer cell lines through protein and gene expression analysis. Proteomics results demonstrated that 540 total proteins and 1473 phospho-proteins significantly changed due to FSS exposure and pathways of interest included early and late estrogen response. The impact of FSS on response to 17β-estradiol (E2) was next evaluated and gene expression analysis revealed repression of ER and E2-mediated genes (PR and SDF1) following exposure to FSS. Western blot demonstrated enhanced phosphorylation of mTOR following exposure to FSS. Taken together, these studies provide initial insight into the effects of FSS on HR signaling in metastatic breast cancer.

Clinical, pathological and gene expression profiling of estrogen receptor discordance in breast cancer

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.

CONCLUSION

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.

SMAD4 depletion contributes to endocrine resistance by integrating ER and ERBB signaling in HR + HER2- breast cancer

Endocrine resistance poses a significant clinical challenge for patients with hormone receptor-positive and human epithelial growth factor receptor 2-negative (HR + HER2-) breast cancer. Dysregulation of estrogen receptor (ER) and ERBB signaling pathways is implicated in resistance development; however, the integration of these pathways remains unclear. While SMAD4 is known to play diverse roles in tumorigenesis, its involvement in endocrine resistance is poorly understood. Here, we investigate the role of SMAD4 in acquired endocrine resistance in HR + HER2- breast cancer. Genome-wide CRISPR screening identifies SMAD4 as a regulator of 4-hydroxytamoxifen (OHT) sensitivity in T47D cells. Clinical data analysis reveals downregulated SMAD4 expression in breast cancer tissues, correlating with poor prognosis. Following endocrine therapy, SMAD4 expression is further suppressed. Functional studies demonstrate that SMAD4 depletion induces endocrine resistance in vitro and in vivo by enhancing ER and ERBB signaling. Concomitant inhibition of ER and ERBB signaling leads to aberrant autophagy activation. Simultaneous inhibition of ER, ERBB, and autophagy pathways synergistically impacts SMAD4-depleted cells. Our findings unveil a mechanism whereby endocrine therapy-induced SMAD4 downregulation drives acquired resistance by integrating ER and ERBB signaling and suggest a rational treatment strategy for endocrine-resistant HR + HER2- breast cancer patients.

Palliative surgery versus non-surgery of the solitary metastatic lesion in De novo metastatic breast cancer: A SEER based study

This study aimed to evaluate whether palliative surgery for metastatic lesion could provide a survival benefit in metastatic breast cancer (MBC) patients with solitary metastasis. De novo MBC patients with solitary distant lesions were enrolled utilizing the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) was conducted to form matched pairs of the surgery group and the non-surgery group. The breast cancer-specific survival (BCSS) and overall survival (OS) outcomes between the 2 groups were compared in the following 3 sample models: the entire cohort of MBC (7665 cases); subgroups of patients with different isolated metastatic organs; and subgroups of patients with different molecular subtypes for each isolated metastatic organ. Compared with the Non-surgery group, the surgery group showed better BCSS and OS before PSM (HR = 0.88, 95% CI = 0.79-0.99, P = .04 and HR = 0.85, 95% CI = 0.76-0.95, P = .006, respectively). After PSM, palliative surgery still provided an OS benefit in patients with brain metastasis and lung metastasis (HR = 0.59, 95% CI = 0.37-0.95, P = .01 and HR = 0.64, 95% CI = 0.45-0.90, P = .02, respectively). Likewise, a better BCSS benefit was also found in the subset of patients with brain metastasis (HR = 0.61, 95% CI = 0.38-1.00, P = .01). Further stratification analysis indicated that patients with the luminal A subtype with brain metastasis have a better BCSS (HR = 0.36, 95% CI = 0.16-0.79, P = .04) and OS (HR = 0.37, 95% CI = 0.18-0.75, P = .03) after undergoing palliative surgery than nonsurgical treatment. Our study originality showed that palliative surgery for metastatic lesion could improve survival prognosis in patients with special single-organ metastasis and specific molecular subtypes. More clinical studies are needed to determine whether palliative surgery should be performed in MBC patients.

Novel Treatment Strategies for Hormone Receptor (HR)-Positive, HER2-Negative Metastatic Breast Cancer

Estrogen receptor (ER)-positive breast cancer (BC) is the most common BC subtype. Endocrine therapy (ET) targeting ER signaling still remains the mainstay treatment option for hormone receptor (HR)-positive BC either in the early or in advanced setting, including different strategies, such as the suppression of estrogen production or directly blocking the ER pathway through SERMs-selective estrogen receptor modulators-or SERDs-selective estrogen receptor degraders. Nevertheless, the development of de novo or acquired endocrine resistance still remains challenging for oncologists. The use of novel ET combined with targeted drugs, such as cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, has significantly improved long-term outcome rates, thus changing the therapeutic algorithm for metastatic BC (MBC) and recently the therapeutic strategy in the adjuvant setting for early high-risk BC. Eluding the resistance to CDK4/6 inhibitors combined with ET is currently an unmet medical need, and there is disagreement concerning the best course of action for patients who continue to progress after this combination approach. Genetic changes in the tumor along its growth uncovered by genomic profiling of recurrent and/or metastatic lesions through tumor and/or liquid biopsies may predict the response or resistance to specific agents, suggesting the best therapeutic strategy for each patient by targeting the altered ER-dependent pathway (novel oral SERDs and a new generation of anti-estrogen agents) or alternative ER-independent signaling pathways such as PI3K/AKT/mTOR or tyrosine kinase receptors (HER2 mutations or HER2 low status) or by inhibiting pathways weakened through germline BRCA1/2 mutations. These agents are being investigated as single molecules and in combination with other target therapies, offering promising weapons to overcome or avoid treatment failure and propose increasingly more personalized treatment approaches. This review presents novel insights into ET and other targeted therapies for managing metastatic HR+/HER2- BC by exploring potential strategies based on clinical evidence and genomic profiling following the failure of the CDK4/6i and ET combination.

Giredestrant for Estrogen Receptor-Positive, HER2-Negative, Previously Treated Advanced Breast Cancer: Results From the Randomized, Phase II acelERA Breast Cancer Study

PURPOSE

To compare giredestrant and physician's choice of endocrine monotherapy (PCET) for estrogen receptor-positive, HER2-negative, advanced breast cancer (BC) in the phase II acelERA BC study (ClinicalTrials.gov identifier: NCT04576455).

METHODS

Post-/pre-/perimenopausal women, or men, age 18 years or older with measurable disease/evaluable bone lesions, whose disease progressed after 1-2 lines of systemic therapy (≤1 targeted, ≤1 chemotherapy regimen, prior fulvestrant allowed) were randomly assigned 1:1 to giredestrant (30 mg oral once daily) or fulvestrant/aromatase inhibitor per local guidelines (+luteinizing hormone-releasing hormone agonist in pre-/perimenopausal women, and men) until disease progression/unacceptable toxicity. Stratification was by visceral versus nonvisceral disease, prior cyclin-dependent kinase 4/6 inhibitor, and prior fulvestrant. The primary end point was investigator-assessed progression-free survival (INV-PFS).

RESULTS

At clinical cutoff (February 18, 2022; median follow-up: 7.9 months; N = 303), the INV-PFS hazard ratio (HR) was 0.81 (95% CI, 0.60 to 1.10; P = .1757). In the prespecified secondary end point analysis of INV-PFS by ESR1 mutation (m) status in circulating tumor DNA-evaluable patients (n = 232), the HR in patients with a detectable ESR1m (n = 90) was 0.60 (95% CI, 0.35 to 1.03) versus 0.88 (95% CI, 0.54 to 1.42) in patients with no ESR1m detected (n = 142). Related grade 3-4 adverse events (AEs), serious AEs, and discontinuations due to AEs were balanced across arms.

CONCLUSION

Although the acelERA BC study did not reach statistical significance for its primary INV-PFS end point, there was a consistent treatment effect with giredestrant across most key subgroups and a trend toward favorable benefit among patients with ESR1-mutated tumors. Giredestrant was well tolerated, with a safety profile comparable to PCET and consistent with known endocrine therapy risks. Overall, these data support the continued investigation of giredestrant in other studies.

Tumor microenvironment responsive nano-herb and CRISPR delivery system for synergistic chemotherapy and immunotherapy

Chemoresistance remains a significant challenge for effective breast cancer treatment which leads to cancer recurrence. CRISPR-directed gene editing becomes a powerful tool to reduce chemoresistance by reprogramming the tumor microenvironment. Previous research has revealed that Chinese herbal extracts have significant potential to overcome tumor chemoresistance. However, the therapeutic efficacy is often limited due to their poor tumor targeting and in vivo durability. Here we have developed a tumor microenvironment responsive nanoplatform (H-MnO2(ISL + DOX)-PTPN2@HA, M(I + D)PH) for nano-herb and CRISPR codelivery to reduce chemoresistance. Synergistic tumor inhibitory effects were achieved by the treatment of isoliquiritigenin (ISL) with doxorubicin (DOX), which were enhanced by CRISPR-based gene editing to target protein tyrosine phosphatase non-receptor type 2 (PTPN2) to initiate long-term immunotherapy. Efficient PTPN2 depletion was observed after treatment with M(I + D)PH nanoparticles, which resulted in the recruitment of intratumoral infiltrating lymphocytes and an increase of proinflammatory cytokines in the tumor tissue. Overall, our nanoparticle platform provides a diverse technique for accomplishing synergistic chemotherapy and immunotherapy, which offers an effective treatment alternative for malignant neoplasms.

The G Protein Estrogen Receptor (GPER) is involved in the resistance to the CDK4/6 inhibitor palbociclib in breast cancer

BACKGROUND

The cyclin D1-cyclin dependent kinases (CDK)4/6 inhibitor palbociclib in combination with endocrine therapy shows remarkable efficacy in the management of estrogen receptor (ER)-positive and HER2-negative advanced breast cancer (BC). Nevertheless, resistance to palbociclib frequently arises, highlighting the need to identify new targets toward more comprehensive therapeutic strategies in BC patients.

METHODS

BC cell lines resistant to palbociclib were generated and used as a model system. Gene silencing techniques and overexpression experiments, real-time PCR, immunoblotting and chromatin immunoprecipitation studies as well as cell viability, colony and 3D spheroid formation assays served to evaluate the involvement of the G protein-coupled estrogen receptor (GPER) in the resistance to palbociclib in BC cells. Molecular docking simulations were also performed to investigate the potential interaction of palbociclib with GPER. Furthermore, BC cells co-cultured with cancer-associated fibroblasts (CAFs) isolated from mammary carcinoma, were used to investigate whether GPER signaling may contribute to functional cell interactions within the tumor microenvironment toward palbociclib resistance. Finally, by bioinformatics analyses and k-means clustering on clinical and expression data of large cohorts of BC patients, the clinical significance of novel mediators of palbociclib resistance was explored.

RESULTS

Dissecting the molecular events that characterize ER-positive BC cells resistant to palbociclib, the down-regulation of ERα along with the up-regulation of GPER were found. To evaluate the molecular events involved in the up-regulation of GPER, we determined that the epidermal growth factor receptor (EGFR) interacts with the promoter region of GPER and stimulates its expression toward BC cells resistance to palbociclib treatment. Adding further cues to these data, we ascertained that palbociclib does induce pro-inflammatory transcriptional events via GPER signaling in CAFs. Of note, by performing co-culture assays we demonstrated that GPER contributes to the reduced sensitivity to palbociclib also facilitating the functional interaction between BC cells and main components of the tumor microenvironment named CAFs.

CONCLUSIONS

Overall, our results provide novel insights on the molecular events through which GPER may contribute to palbociclib resistance in BC cells. Additional investigations are warranted in order to assess whether targeting the GPER-mediated interactions between BC cells and CAFs may be useful in more comprehensive therapeutic approaches of BC resistant to palbociclib.

The somatic mutation profile of estrogen receptor-positive HER2-negative metastatic breast cancer in Brazilian patients

Background

Breast cancer is the leading cause of cancer death among women worldwide. Studies about the genomic landscape of metastatic breast cancer (MBC) have predominantly originated from developed nations. There are still limited data on the molecular epidemiology of MBC in low- and middle-income countries. This study aims to evaluate the prevalence of mutations in the PI3K-AKT pathway and other actionable drivers in estrogen receptor (ER)+/HER2- MBC among Brazilian patients treated at a large institution representative of the nation's demographic diversity.

Methods

We conducted a retrospective observational study using laboratory data (OC Precision Medicine). Our study included tumor samples from patients with ER+/HER2- MBC who underwent routine tumor testing from 2020 to 2023 and originated from several Brazilian centers within the Oncoclinicas network. Two distinct next-generation sequencing (NGS) assays were used: GS Focus (23 genes, covering PIK3CA, AKT1, ESR1, ERBB2, BRCA1, BRCA2, PALB2, TP53, but not PTEN) or GS 180 (180 genes, including PTEN, tumor mutation burden [TMB] and microsatellite instability [MSI]).

Results

Evaluation of tumor samples from 328 patients was undertaken, mostly (75.6%) with GS Focus. Of these, 69% were primary tumors, while 31% were metastatic lesions. The prevalence of mutations in the PI3K-AKT pathway was 39.3% (95% confidence interval, 33% to 43%), distributed as 37.5% in PIK3CA and 1.8% in AKT1. Stratification by age revealed a higher incidence of mutations in this pathway among patients over 50 (44.5% vs 29.1%, p=0.01). Among the PIK3CA mutations, 78% were canonical (included in the alpelisib companion diagnostic non-NGS test), while the remaining 22% were characterized as non-canonical mutations (identifiable only by NGS test). ESR1 mutations were detected in 6.1%, exhibiting a higher frequency in metastatic samples (15.1% vs 1.3%, p=0.003). Additionally, mutations in BRCA1, BRCA2, or PALB2 were identified in 3.9% of cases, while mutations in ERBB2 were found in 2.1%. No PTEN mutations were detected, nor were TMB high or MSI cases.

Conclusion

We describe the genomic landscape of Brazilian patients with ER+/HER2- MBC, in which the somatic mutation profile is comparable to what is described in the literature globally. These data are important for developing precision medicine strategies in this scenario, as well as for health systems management and research initiatives.

Causal effect analysis of estrogen receptor associated breast cancer and clear cell ovarian cancer

BACKGROUND

Evidence indicates that the risk of developing a secondary ovarian cancer (OC) is correlated with estrogen receptor (ER) status. However, the clinical significance of the relationship between ER-associated breast cancer (BC) and clear cell ovarian cancer (CCOC) remains elusive.

METHODS

Independent single nucleotide polymorphisms (SNPs) strongly correlated with exposure were extracted, and those associated with confounders and outcomes were removed using the PhenoScanner database. SNP effects were extracted from the outcome datasets with minor allele frequency > 0.01 as the filtration criterion. Next, valid instrumental variables (IVs) were obtained by harmonizing exposure and outcome effects and further filtered based on F-statistics (> 10). Mendelian randomization (MR) assessment of valid IVs was carried out using inverse variance weighted (IVW), MR Egger (ME), weighted median (WM), and multiplicative random effects-inverse variance weighted (MRE-IVW) methods. For sensitivity analysis and visualization of MR findings, a heterogeneity test, a pleiotropy test, a leave-one-out test, scatter plots, forest plots, and funnel plots were employed.

RESULTS

MR analyses with all four methods revealed that CCOC was not causally associated with ER-negative BC (IVW results: odds ratio (OR) = 0.89, 95% confidence interval (CI) = 0.66-1.20, P = 0.431) or ER-positive BC (IVW results: OR = 0.99, 95% CI = 0.88-1.12, P = 0.901). F-statistics were computed for each valid IV, all of which exceeded 10. The stability and reliability of the results were confirmed by sensitivity analysis.

CONCLUSIONS

Our findings indicated that CCOC dids not have a causal association with ER-associated BC. The absence of a definitive causal link between ER-associated BC and CCOC suggested a minimal true causal influence of ER-associated BC exposure factors on CCOC. These results indicated that individuals afflicted by ER-associated BC could alleviate concerns regarding the developing of CCOC, thereby aiding in preserving their mental well-being stability and optimizing the efficacy of primary disease treatment.

Discovery of Novel ERα and Aromatase Dual-Targeting PROTAC Degraders to Overcome Endocrine-Resistant Breast Cancer

Estrogen receptor α (ERα) plays a pivotal role in the proliferation, differentiation, and migration of breast cancer (BC) cells, and aromatase (ARO) is a crucial enzyme in estrogen synthesis. Hence, it is necessary to inhibit estrogen production or the activity of ERα for the treatment of estrogen receptor-positive (ER+) BC. Herein, we present a new category of dual-targeting PROTAC degraders designed to specifically target ERα and ARO. Among them, compound 18c bifunctionally degrades and inhibits ERα/ARO, thus effectively suppressing the proliferation of MCF-7 cells while showing negligible cytotoxicity to normal cells. In vivo, 18c promotes the degradation of ERα and ARO and inhibits the growth of MCF-7 xenograft tumors. Finally, compound 18c demonstrates promising antiproliferative and ERα degradation activity against the ERαMUT cells. These findings suggest that 18c, being the inaugural dual-targeting degrader for ERα and ARO, warrants further advancement for the management of BC and the surmounting of endocrine resistance.

Exploring the potential of Huangqin Tang in breast cancer treatment using network pharmacological analysis and experimental verification

AIMS OF THIS STUDY

This study aims to investigate the potential of Huangqin Tang (HQT), a traditional Chinese medicine formulation, in the treatment of breast cancer (BC) through a comprehensive approach integrating network pharmacology, molecular docking, and experimental validation.

METHODS

Chemical composition and target information of HQT were collected using the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP). Disease-related target genes were obtained from the GeneCards database. Network pharmacological analysis, including construction of compound-disease-target networks and protein-protein interaction networks, was performed. Molecular docking simulations were conducted to evaluate the binding affinity between HQT components and key targets. Experimental validation was carried out using cell viability assays, clone formation assays, flow cytometry, Western blotting, and pathway analysis.

RESULTS

A total of 210 candidate targets were identified. Network analysis revealed STAT3, AKT1, MAPK3 etc. as central targets. Enrichment analysis suggested HQT may exert anti-tumor effects through regulating lipid metabolism and inflammation related pathways. Molecular docking showed that the key compounds baicalein, wogonin, kaempferol and quercetin all bound effectively to MAPK1. The binding of baicalein to IL6 and naringenin to TNF-α was also relatively stable. The experimental results demonstrated that HQT effectively inhibited the proliferation of breast cancer cells, with IC50 values of 2.334 mg/mL and 1.749 mg/mL in MCF-7 cells at 24 h and 48 h, and IC50 values of 1.286 mg/mL and 1.496 mg/mL in MDA-MB-231 cells at 24 h and 48 h, respectively. Furthermore, HQT induced cell cycle arrest at the G2/M phase in breast cancer cells and downregulated the expression of related proteins including CDK1, Cyclin B1, CDK2, and Cyclin E. Additionally, HQT promoted apoptosis in breast cancer cells by upregulating the expression of Bak and CC-3, while downregulating the expression of Bcl-2. Notably, HQT also exhibited regulatory effects on the HIF-1 signaling pathway.

CONCLUSIONS

This study provides insights into the potential multi-component and multi-target mechanisms of HQT against BC, suggesting it may achieve therapeutic effects through regulating inflammatory response and cancer-related pathways via the identified active compounds and targets. The findings highlight the importance of integrating traditional medicine with modern approaches for the development of novel cancer therapies.

A bibliometric and visualization analysis of research trends and hotspots on targeted therapy for breast cancer from 2003 to 2022

Background

Breast cancer is a significant public health issue, exhibiting the most pronounced occurrence and fatality rates among malignant neoplasms globally. Targeted therapy is a medical intervention that focuses on specific molecular markers. This study aims to investigate and evaluate the current research trends and directions in the field of targeted therapy for breast cancer using bibliometric analysis.

Method

The Web of Science database was utilized to retrieve relevant articles published between 2003 and 2022. The VOSviewer software and Bibliometrix package in the R language were employed to conduct co-occurrence and clustering analyses of authors, countries, institutions, journals, references, and the CiteSpace tool was utilized for keyword burst detection.

Results

A total of 2,258 articles were included and the annual number of publications increased rapidly. The most prolific country on this topic was the USA (n=898, 39.77%) and the University of Texas MD Anderson Cancer Center published most papers (n=93). Dennis J. Slamon and Gabriel N. Hortobagyi stood out in the field, with Dennis J. Slamon leading in terms of co-citations(n=653) and Gabriel N. Hortobagyi topping the list in terms of published articles(n=18). The most productive journal was Breast Cancer Research and Treatment and the most cited journal was Journal of Clinical Oncology. The clustering of keywords indicated that the primary focus of researches in the past two decades was on the development and clinical evaluation of tumor-targeted drugs associated with the epidermal growth factor receptor (EGFR) family signaling pathway, and explored mechanisms related to biological behavior of breast cancer. Keywords co-occurrence and burst analysis identified current research hotspots and potential research trends.

Conclusion

This study employed bibliometric analysis to examine research on targeted therapy for breast cancer over a span of 20 years, and identified development trends of research and elucidated potential research trajectories in the domain of this topic. This study helps in the identification of prospective collaborators and partner institutions for researchers.

PIK3CA mutations in endocrine-resistant breast cancer

Around 75% of breast cancer (BC) patients have tumors expressing the predictive biomarker estrogen receptor α (ER) and are offered endocrine therapy. One-third eventually develop endocrine resistance, a majority with retained ER expression. Mutations in the phosphatidylinositol bisphosphate 3-kinase (PI3K) catalytic subunit encoded by PIK3CA is a proposed resistance mechanism and a pharmacological target in the clinical setting. Here we explore the frequency of PIK3CA mutations in endocrine-resistant BC before and during treatment and correlate to clinical features. Patients with ER-positive (ER +), human epidermal growth factor receptor 2 (HER2)-negative primary BC with an ER + relapse within 5 years of ongoing endocrine therapy were retrospectively assessed. Tissue was collected from primary tumors (n = 58), relapse tumors (n = 54), and tumor-free lymph nodes (germline controls, n = 62). Extracted DNA was analyzed through panel sequencing. Somatic mutations were observed in 50% (31/62) of the patients, of which 29% occurred outside hotspot regions. The presence of PIK3CA mutations was significantly associated with nodal involvement and mutations were more frequent in relapse than primary tumors. Our study shows the different PIK3CA mutations in endocrine-resistant BC and their fluctuations during therapy. These results may aid investigations of response prediction, facilitating research deciphering the mechanisms of endocrine resistance.

Predictors of Endocrine Resistance in a Cohort of Mexican Breast Cancer Patients

Purpose

This study aimed to determine the prevalence of endocrine resistance in a cohort of Hispanic Mexican breast cancer (BC) patients receiving care at Instituto Nacional de Cancerología (INCan). Additionally, the clinical-pathological factors associated with endocrine resistance were identified, and their impact on patient survival was explored.

Methods

A retrospective analysis of 200 BC patients who attended INCan between 2012 and 2016 with estrogen receptor (ER) and progesterone receptor (PR) positive tumors was made. Endocrine resistance was defined according to the International Consensus Guidelines for Advance Breast Cancer 2 definition. Their clinicopathological characteristics were analyzed to determine the association with endocrine resistance presence. We used sensitivity analyses and multivariate-adjusted logistic regressions, Kaplan-Meier curves, and multivariate-adjusted Cox regressions. P-value < 0.05 was considered as statistically significant.

Results

Endocrine resistance was observed in 32.5% of patients included in this study. The distinction between hormone resistance and sensitivity was influenced by tumor size and node status. It had a mean diameter of 7.15 cm in endocrine resistance cases compared to 5.71 cm in non-endocrine, with N3 status present in 20% of endocrine resistance cases versus only 2.2% in non-endocrine (p-value < 0.001). The clinical stage exhibited a strong association with endocrine resistance (Risk Ratio [RR] 4.39, 95% confidence interval [95%CI] 1.50, 11.43). Furthermore, endocrine resistance significantly impacted mortality during the follow-up, with a Hazard Ratio [HR] of 23.7 (95%CI 5.20, 108.42) in multivariable-adjusted models. However, a complete pathological response reduced the endocrine resistance risk, as demonstrated by a Risk Ratio (RR) of 0.15 (95% CI 0.03, 0.75).

Conclusions

Advanced clinical stage at diagnosis predicted endocrine resistance in Hispanic Mexican BC patients. Complete pathologic response in locally advanced disease patients was also a key predictor of endocrine resistance. These results indicated that endocrine resistance was a critical factor in BC during follow-up.

High expression of CCNB2 is an independent predictive poor prognostic biomarker and correlates with immune infiltrates in breast carcinoma

Background

Cyclin B2 (CCNB2) is associated with cell cycle progression, acting as a cell cycle checkpoint in progression of G2/M transition. In many cancer patients, it has been observed that overexpression of CCNB2 enhances tumor invasiveness and leads to adverse prognosis. However, the association of CCNB2 with the tumor microenvironment remains unclear. Therefore, it is necessary to clarify the associations of CCNB2 with the immune status and prognosis of breast carcinoma (BRCA).

Methods

Gene expression and clinical data for BRCA were obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases, followed by association analyses of CCNB2 expression with prognosis, immune cell infiltration, and immune checkpoints. This study further performed drug sensitivity analysis and constructed a prognostic nomogram for CCNB2.

Results

3619 differentially expressed genes were identified in BRCA, including CCNB2 that emerged as a key gene in the network. High CCNB2 expression correlated with poor prognosis. Functional analysis demonstrated enrichment of CCNB2 co-expressed genes with the cell cycle, cancer progression, cell energy, and immune pathways. Microsatellite instability and tumor mutation burden analyses indicated CCNB2 as a candidate immunotherapy target. Tumor-infiltrating myeloid-derived suppressor cells, regulatory T cells, and T helper 2 cells were associated with CCNB2-related tumor progression and metastasis. CCNB2 expression positively correlated with immune checkpoints, indicating that high CCNB2 expression might facilitate tumor immune escape. Tumors with high CCNB2 expression showed sensitivity to phosphoinositide 3-kinase-protein kinase B-mammalian target of rapamycin and cyclin-dependent kinase (CDK) 4/6 inhibitors, and the nomogram had good prognostic predictive ability for patients with BRCA.

Conclusions

CCNB2 may play a crucial role in tumorigenesis and serve as an independent prognostic biomarker associated with tumor microenvironment, tumor immune infiltration and immunotherapy in BRCA.

Overexpression of COL11A1 confers tamoxifen resistance in breast cancer

Breast cancer is the most commonly diagnosed malignancy and benefits from endocrine agents such as tamoxifen. However, the development of drug resistance in cancerous cells often leads to recurrence, thus limiting the therapeutic benefit. Identification of potential biomarkers that can predict response to tamoxifen and recognize patients who will clinically benefit from this therapy is urgently needed. In this study, we report that high collagen type XI alpha 1 (COL11A1) expression was associated with poor therapeutic response and prognosis in breast cancer patients treated with tamoxifen. To confirm the role of COL11A1 in the development of tamoxifen resistance, we established MCF-7/COL11A1 and T47D/COL11A1 cell lines, which stably expressed COL11A1. Compared with parental MCF-7 and T47D, MCF-7/COL11A1 and T47D/COL11A1 cells were more resistant to 4-OHT-induced growth inhibition. Moreover, the level of COL11A1 expression was upregulated in tamoxifen-resistant MCF-7/TamR and T47D/TamR cell lines, and depletion of COL11A1 markedly sensitized the cells to 4-OHT in vitro and in vivo. Interestingly, the level of estrogen receptor α (ERα) expression was elevated, probably due to the increased COL11A1 in TamR cells. In addition, knockdown of COL11A1 decreased the expression of ERα and its downstream target genes. Overall, our findings suggest that overexpressed COL11A1 contributes to tamoxifen resistance, and targeting COL11A1 holds great promise for reversing endocrine resistance.