Hormonoresistance in advanced breast cancer: a new revolution in endocrine therapy

Autophagy and senescence facilitate the development of antiestrogen resistance in ER positive breast cancer

Estrogen receptor positive (ER+) breast cancer is the most common breast cancer diagnosed annually in the US with endocrine-based therapy as standard-of-care for this breast cancer subtype. Endocrine therapy includes treatment with antiestrogens, such as selective estrogen receptor modulators (SERMs), selective estrogen receptor downregulators (SERDs), and aromatase inhibitors (AIs). Despite the appreciable remission achievable with these treatments, a substantial cohort of women will experience primary tumor recurrence, subsequent metastasis, and eventual death due to their disease. In these cases, the breast cancer cells have become resistant to endocrine therapy, with endocrine resistance identified as the major obstacle to the medical oncologist and patient. To combat the development of endocrine resistance, the treatment options for ER+, HER2 negative breast cancer now include CDK4/6 inhibitors used as adjuvants to antiestrogen treatment. In addition to the dysregulated activity of CDK4/6, a plethora of genetic and biochemical mechanisms have been identified that contribute to endocrine resistance. These mechanisms, which have been identified by lab-based studies utilizing appropriate cell and animal models of breast cancer, and by clinical studies in which gene expression profiles identify candidate endocrine resistance genes, are the subject of this review. In addition, we will discuss molecular targeting strategies now utilized in conjunction with endocrine therapy to combat the development of resistance or target resistant breast cancer cells. Of approaches currently being explored to improve endocrine treatment efficacy and patient outcome, two adaptive cell survival mechanisms, autophagy, and "reversible" senescence, are considered molecular targets. Autophagy and/or senescence induction have been identified in response to most antiestrogen treatments currently being used for the treatment of ER+ breast cancer and are often induced in response to CDK4/6 inhibitors. Unfortunately, effective strategies to target these cell survival pathways have not yet been successfully developed. Thus, there is an urgent need for the continued interrogation of autophagy and "reversible" senescence in clinically relevant breast cancer models with the long-term goal of identifying new molecular targets for improved treatment of ER+ breast cancer.

Genome-wide analyses reveal the regulatory roles of DNA methylation-regulated alternative promoter transcripts in breast cancer

A certain proportion of genes are regulated by multiple, distinct promoters, revealing a dynamic landscape of the cancer transcriptome. However, the contribution of alternative promoters (APs) in breast cancer (BRCA) remains largely unexplored. Here, we identified 3654 genes with multiple promoters in BRCA patients, and 53 of them could generate distinct AP transcripts that are dysregulated and prognosis-related in BRCA, namely prognosis-related dysregulated AP (prdeAP) transcripts. Interestingly, when we searched for the genomic signatures of these prdeAP genes, we found that the promoter regions of 92% of the prdeAP genes were enriched with abundant DNA methylation signals. Through further bioinformatic analysis and experimental validation, we showed that AP selections of TANK, UNKL, CCL28, and MAP1LC3A were regulated by DNA methylation upon their corresponding promoter regions. Functionally, by overexpressing AP variants of TANK, we found that TANK|55731 could dramatically suppress MDA-MB-231 cell proliferation and migration. Meanwhile, pan-cancer survival analyses suggested that AP variants of TANK provided more accurate prognostic predictive ability than TANK gene in a variety of tumor types, including BRCA. Together, by uncovering the DNA methylation-regulated AP transcripts with tumor prognostic features, our work revealed a novel layer of regulators in BRCA progression and provided potential targets that served as effective biomarkers for anti-BRCA treatment.

Efficacy and safety of tucidinostat in patients with advanced hormone receptor-positive human epidermal growth factor receptor 2-negative breast cancer: real-world insights

Background

Tucidinostat, which is a subtype-selective histone deacetylase inhibitor, has been approved in China for the treatment of hormone receptor-positive (HR+) human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC). However, existing evidence mainly stemmed from randomized controlled trials, and might have limitations in representing the complexities of clinical practice and diverse patient populations. Therefore, there is a need to explore the efficacy and optimal therapeutic modality for tucidinostat in real-world clinical settings.

Methods

The objective of this real-world study was to analyze the clinical data of 47 patients with HR+/HER2- ABC who received tucidinostat treatment at West China Hospital, Sichuan University, between August 2020 and May 2023. The primary outcomes were progression-free survival (PFS) and clinical benefit rate [CBR; defined as partial response (PR) and stable disease (SD) for ≥6 months on clinical evaluation].

Results

A total of 47 patients were included, and the median follow-up time was 18.20 months. The median line of tucidinostat therapy was 3 (range, 1-9). In all, 52.17% patients were treated with tucidinostat plus fulvestrant, while 38.30% were treated with tucidinostat plus aromatase inhibitors. Notably, 10.64% of the patients with rapidly progressing visceral metastases received tucidinostat plus endocrine therapy as maintenance treatment after achieving disease control with chemotherapy. The median PFS was 4.43 months [95% confidence interval (CI), 2.77-10.53], and the median overall survival was 19.57 months (95% CI, 12.83-not reached). The 6-month CBR for the overall population was 41.86%. Patients undergoing maintenance therapy demonstrated a significantly longer PFS than did those who did not receive it as maintenance therapy (14.13 vs. 3.93 months; P=0.01). Univariate Cox regression analysis showed that use of tucidinostat in lines 1-2, use of tucidinostat plus fulvestrant, presence of one metastatic site, and lack of brain metastasis were favorable factors for PFS. Thrombocytopenia was the most frequently reported adverse event, with an incidence rate of 31.91% at all grades and 14.89% at grade ≥3. Four (8.51%) patients discontinued the treatment.

Conclusions

For patients with HR+/HER2- ABC, tucidinostat combination therapy offers certain survival benefits with controllable safety. Furthermore, compared with non-maintenance therapy, maintenance therapy after chemotherapy may have promising efficacy.

Synergistic efficacy of PI3Kδ inhibitor with anti-PD-1 mAbs in immune-humanized PDX model of endocrine resistance hormone receptor-positive advanced breast cancer

Purpose

Endocrine resistance hormone receptor-positive (HR+) advanced breast cancer (ABC) is generally insensitive to immunecheckpoint inhibitors (ICIs). This study sought to determine whether PI3Kδ inhibitor could enhance the sensitivity of endocrine resistance HR + advanced BC to ICIs by reducing immune evasion.

Methods

Patient-derived HR + ABC xenografts were implanted into immune-humanized NSG mice and subsequently treated with YY20394 (PI3Kδ inhibitor) and camrelizumab. The mice were monitored for tumor progression, biochemical blood indicators, and peripheral blood T-cell subsets. The xenografted tumors were collected at the end of the treatment cycle and subjected to HE staining, immunohistochemistry and protein phosphorylation analysis. Besides, the xenografted tumors were also used to isolate primary breast cancer cells (BCCs) and regulatory T-cells (Tregs), which were subsequently used to evaluate drug sensitivity in vitro.

Results

The humanized PDX model showed a favorable initial treatment response to camrelizumab combined with YY20394 and manageable toxicity. YY20394 plus camrelizumab showed a strong inhibitory effect on HR + BC in vivo mediated by suppression of Treg activity and an increased proportion of CD8+ T cells. Mice bearing tumors treated with YY20394 and camrelizumab had less invasion, mitotic figures, and ki67 expression, while having higher IL-12 expression compared with other groups. Mechanistically, YY20394 only effectively inhibited the PI3K pathway and proliferation activity in Tregs but not in BCCs.

Conclusion

Our study suggests PI3Kδ inhibitor could the enhance the efficacy of ICIs in HR + BC PDX models by combating immune suppression and provides a feasible approach that may overcome the resistance of ICIs in HR + BC patients.

ZNF703 mRNA-Targeting Antisense Oligonucleotide Blocks Cell Proliferation and Induces Apoptosis in Breast Cancer Cell Lines

The luminal B molecular subtype of breast cancers (BC) accounts for more than a third of BCs and is associated with aggressive clinical behavior and poor prognosis. The use of endocrine therapy in BC treatment has significantly contributed to the decrease in the number of deaths in recent years. However, most BC patients with prolonged exposure to estrogen receptor (ER) selective modulators such as tamoxifen develop resistance and become non-responsive over time. Recent studies have implicated overexpression of the ZNF703 gene in BC resistance to endocrine drugs, thereby highlighting ZNF703 inhibition as an attractive modality in BC treatment, especially luminal B BCs. However, there is no known inhibitor of ZNF703 due to its nuclear association and non-enzymatic activity. Here, we have developed an antisense oligonucleotide (ASO) against ZNF703 mRNA and shown that it downregulates ZNF703 protein expression. ZNF703 inhibition decreased cell proliferation and induced apoptosis. Combined with cisplatin, the anti-cancer effects of ZNF703-ASO9 were improved. Moreover, our work shows that ASO technology may be used to increase the number of targetable cancer genes.

Long Non-Coding RNAs, Cell Cycle, and Human Breast Cancer

The long non-coding RNAs (lncRNAs) constitute an important class of the human transcriptome. The discovery of lncRNAs provided one of many unexpected results of the post-genomic era and uncovered a huge number of previously ignored transcriptional events. In recent years, lncRNAs are known to be linked with human diseases, with particular focus on cancer. Growing evidence has indicated that dysregulation of lncRNAs in breast cancer (BC) is strongly associated with the occurrence, development, and progress. Increasing numbers of lncRNAs have been found to interact with cell cycle progression and tumorigenesis in BC. The lncRNAs can exert their effect as a tumor suppressor or oncogene and regulate tumor development through direct or indirect regulation of cancer-related modulators and signaling pathways. What is more, lncRNAs are excellent candidates for promising therapeutic targets in BC due to the features of high tissue and cell-type specific expression. However, the underlying mechanisms of lncRNAs in BC still remain largely undefined. Here, we concisely summarize and sort out the current understanding of research progress in relationships of the roles for lncRNA in regulating the cell cycle. We also summarize the evidence for aberrant lncRNA expression in BC, and the potential for lncRNA to improve BC therapy is also discussed. Together, lncRNAs can be considered as exciting therapeutic candidates whose expression can be altered to impede BC progression.

Zinc-finger protein CXXC5 promotes breast carcinogenesis by regulating the TSC1/mTOR signaling pathway

CXXC5, a member of the CXXC family of zinc-finger proteins, is associated with numerous pathological processes. However, the pathophysiological function of CXXC5 has not been clearly established. Herein, we found that CXXC5 interacts with the CRL4B and NuRD complexes. Screening of transcriptional targets downstream of the CXXC5-CRL4B-NuRD complex by next-generation sequencing (chromatin immunoprecipitation sequencing) revealed that the complex regulates the transcriptional repression process of a cohort of genes, including TSC1 (tuberous sclerosis complex subunit 1), which play important roles in cell growth and mammalian target of rapamycin signaling pathway regulation, and whose abnormal regulation results in the activation of programmed cell death-ligand protein 1 (PD-L1). Intriguingly, CXXC5 expression increased after stimulation with vitamin B2 but decreased after vitamin D treatment. We also found that the CXXC5-CRL4B-NuRD complex promotes the proliferation of tumor cells in vitro and accelerates the growth of breast cancer in vivo. The expression of CXXC5, CUL4B, and MTA1 increased during the occurrence and development of breast cancer, and correspondingly, TSC1 expression decreased. Meanwhile, a high expression of CXXC5 was positively correlated with the histological grade of high malignancy and poor survival of patients. In conclusion, our study revealed that CXXC5-mediated TSC1 suppression activates the mammalian target of rapamycin pathway, reduces autophagic cell death, induces PD-L1-mediated immune suppression, and results in tumor development, shedding light on the mechanism of the pathophysiological function of CXXC5.

The diagnostic accuracy of PIK3CA mutations by circulating tumor DNA in breast cancer: an individual patient data meta-analysis

Background:

The circulating tumor DNA (ctDNA) diagnostic accuracy for detecting phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutations in breast cancer (BC) is under discussion. We aimed to compare plasma and tissue PIK3CA alterations, encompassing factors that could affect the results.

Methods:

Two reviewers selected studies from different databases until December 2020. We considered BC patients with matched tumor tissue and plasma ctDNA. We performed meta-regression and subgroup analyses to explore sources of heterogeneity concerning tumor burden, diagnostic technique, sample size, sampling time, biological subtype, and hotspot mutation. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and the related area under the curve (AUC) were elaborated for the overall population and each subgroup.

Results:

The pooled analysis was carried out on 25 cohorts for a total of 1966 patients. The overall ctDNA sensitivity and specificity were 0.73 (95% CI: 0.70–0.77) and 0.87 (95% CI: 0.85–0.89). The AUC was 0.93. Pooled concordance, negative predictive value and positive predictive value values were 0.87 (95% CI: 0.82–0.92), 0.86 (95% CI: 0.81–0.90), and 0.89 (95% CI: 0.81–0.95) with pooled PLR, NLR, and DOR of 7.94 (95% CI: 4.90–12.86), 0.33 (95% CI: 0.25–0.45), and 33.41 (95% CI: 17.23–64.79), respectively. The pooled results consistently favored next-generation sequencing (NGS)- over polymerase chain reaction-based methodologies. The best ctDNA performance in terms of sensitivity, specificity, and AUC (0.85, 0.99, and 0.94, respectively) was observed in the low-time sampling subgroup (⩽18 days between tissue and plasma collection). Meta-regression and subgroup analyses highlighted sampling time as a possible major cause of heterogeneity.

Conclusions:

These findings reliably estimate the high ctDNA accuracy for the detection of PIK3CA mutations. A ctDNA-first approach for the assessment of PIK3CA mutational status by NGS may accurately replace tissue tumor sampling, representing the preferable strategy at diagnosis of metastatic BC in patients who present with visceral involvement and at least two metastatic lesions, primarily given low clinical compliance or inaccessible metastatic sites.

Endocrine therapy resistance: what we know and future directions

Endocrine resistance is a major hurdle in the treatment of estrogen receptor (ER)-positive breast cancer. When abnormally regulated, molecular signals responsible for cellular proliferation, as well as ER itself, allow for cellular evasion of ER-dependent treatments. Therefore, pharmacological treatments that target these evasion mechanisms are beneficial for the treatment of endocrine-resistant breast cancers. This review summarizes currently understood molecular signals that contribute to endocrine resistance and their crosstalk that stem from mitogen-activated protein kinase (MAPK), phosphoinositol-3 kinase/protein kinase B (PI3K/AKT), mechanistic target of rapamycin (mTOR), cyclin-dependent kinases 4 and 6 (CDK4/6) and aberrant ER function. Recent clinical trials that target these molecular signals as a treatment strategy for endocrine-resistant breast cancer are also highlighted.

Anti-Inflammatory, Antioxidant, Moisturizing, and Antimelanogenesis Effects of Quercetin 3-O-β-D-Glucuronide in Human Keratinocytes and Melanoma Cells via Activation of NF-κB and AP-1 Pathways

Quercetin 3-O-β-D-glucuronide (Q-3-G), the glucuronide conjugate of quercetin, has been reported as having anti-inflammatory properties in the lipopolysaccharide-stimulated macrophages, as well as anticancer and antioxidant properties. Unlike quercetin, which has been extensively described to possess a wide range of pharmacological activities including skin protective effects, the pharmacological benefits and mechanisms Q-3-G in the skin remained to be elucidated. This study focused on characterizing the skin protective properties, including anti-inflammatory and antioxidant properties, of Q-3-G against UVB-induced or H₂O₂-induced oxidative stress, the hydration effects, and antimelanogenesis activities using human keratinocytes (HaCaT) and melanoma (B16F10) cells. Q-3-G down-regulated the expression of the pro-inflammatory gene and cytokine such as cyclooxygenase-2 (COX-2) and tumor necrosis factor (TNF)-α in H₂O₂ or UVB-irradiated HaCaT cells. We also showed that Q-3-G exhibits an antioxidant effect using free radical scavenging assays, flow cytometry, and an increased expression of nuclear factor erythroid 2- related factor 2 (Nrf2). Q-3-G reduced melanin production in α-melanocyte-stimulating hormone (α-MSH)-induced B16F10 cells. The hydration effects and mechanisms of Q-3-G were examined by evaluating the moisturizing factor-related genes, such as transglutaminase-1 (TGM-1), filaggrin (FLG), and hyaluronic acid synthase (HAS)-1. In addition, Q-3-G increased the phosphorylation of c-Jun, Jun N-terminal kinase (JNK), Mitogen-activated protein kinase (MAPK) kinase 4 (MKK4), and TAK1, involved in the MAPKs/AP-1 pathway, and the phosphorylation of IκBα, IκB kinase (IKK)-α, Akt, and Src, involved in the NF-κB pathway. Taken together, we have demonstrated that Q-3-G exerts anti-inflammatory, antioxidant, moisturizing, and antimelanogenesis properties in human keratinocytes and melanoma cells through NF-κB and AP-1 pathways.

Endocrine resistance in breast cancer: from molecular mechanisms to therapeutic strategies

Estrogen receptor-positive (ER +) breast cancer accounts for approximately 75% of all breast cancers. Endocrine therapies, including selective ER modulators (SERMs), aromatase inhibitors (AIs), and selective ER down-regulators (SERDs) provide substantial clinical benefit by reducing the risk of disease recurrence and mortality. However, resistance to endocrine therapies represents a major challenge, limiting the success of ER + breast cancer treatment. Mechanisms of endocrine resistance involve alterations in ER signaling via modulation of ER (e.g., ER downregulation, ESR1 mutations or fusions); alterations in ER coactivators/corepressors, transcription factors (TFs), nuclear receptors and epigenetic modulators; regulation of signaling pathways; modulation of cell cycle regulators; stress signaling; and alterations in tumor microenvironment, nutrient stress, and metabolic regulation. Current therapeutic strategies to improve outcome of endocrine-resistant patients in clinics include inhibitors against mechanistic target of rapamycin (mTOR), cyclin-dependent kinase (CDK) 4/6, and the phosphoinositide 3-kinase (PI3K) subunit, p110α. Preclinical studies reveal novel therapeutic targets, some of which are currently tested in clinical trials as single agents or in combination with endocrine therapies, such as ER partial agonists, ER proteolysis targeting chimeras (PROTACs), next-generation SERDs, AKT inhibitors, epidermal growth factor receptor 1 and 2 (EGFR/HER2) dual inhibitors, HER2 targeting antibody-drug conjugates (ADCs) and histone deacetylase (HDAC) inhibitors. In this review, we summarize the established and emerging mechanisms of endocrine resistance, alterations during metastatic recurrence, and discuss the approved therapies and ongoing clinical trials testing the combination of novel targeted therapies with endocrine therapy in endocrine-resistant ER + breast cancer patients.

Real-world effectiveness and sensitivity of palbociclib plus endocrine therapy in HR+/HER2- patients with metastatic breast cancer

Palbociclib has shown satisfactory outcomes when combined with endocrine therapy (ET) in hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (MBC). However, data in Asia are currently scarce.This retrospective study aimed to evaluate the real-world effectiveness, sensitivity, and toxicity of palbociclib plus ET in HR+/HER2- MBC in North China. We recruited patients with HR+/HER2- MBC from August 2018 to July 2020 across 7 hospitals in North China. The primary endpoint was to evaluate progression-free survival (PFS) after initial progress on palbociclib therapy. The secondary endpoints included determining predictive biomarkers of palbociclib sensitivity and toxicity of palbociclib.A total of 54 patients were analyzed in this cohort with an estimated median follow-up time of 14.3 months. Patients who received palbociclib as a first-line treatment showed significantly prolonged PFS compared with those who received palbociclib as a second-line or beyond treatment (21.8 months vs 15.9 months vs 6.8 months) (P < .001). Besides, patients with Ki67 <30% (P = .024) and PR ≥20% (P = .041) in metastatic tumors had significantly longer PFS. The Cox proportional-hazards regression analyses proved that different lines (P = .001 in multivariate analysis), Ki67 <30% (P = .035 in multivariate analysis), and PR ≥20% (P = .045 in univariate analysis) in metastatic tumors affected PFS significantly. The most common adverse events were hematologic, with 31.48% of patients having neutropenia.Palbociclib plus ET significantly prolonged PFS for patients with HR+/HER2- MBC who received first-line therapy, with manageable toxicity. The values of Ki67 and PR in metastatic tumors may be potential predictive biomarkers of palbociclib sensitivity.

The Place of Chemotherapy in The Evolving Treatment Landscape for Patients With HR-positive/HER2-negative MBC

Endocrine therapy (ET) for the treatment of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR-positive/HER2-negative) metastatic breast cancer (MBC) has changed markedly over recent years with the emergence of new ETs and the use of molecularly targeted agents. Cytotoxic chemotherapy continues, however, to have an important role in these patients and it is important to maximize its efficacy while minimizing toxicity to optimize outcomes. This review examines current HR-positive/HER2-negative MBC clinical guidelines and addresses key questions around the use of chemotherapy in the face of emerging therapeutic options. Specifically, the indications for chemotherapy in patients with HR-positive/HER2-negative MBC and the choice of optimal chemotherapy are discussed.

Real-World Efficacy of Fulvestrant Monotherapy as the First Treatment or Maintenance Treatment in Patients with Metastatic Breast Cancer

Background

Fulvestrant 500 mg monotherapy is recommended as the first-line endocrine treatment in postmenopausal women with hormone receptor-positive metastatic breast cancer (MBC). It is also used in MBC maintenance treatment. However, few studies have compared the efficacy of fulvestrant during the initial treatment with that during maintenance treatment.

Patients and Methods

MBC patients who were treated with fulvestrant either as initial therapy for metastatic disease or after progression following one line of chemotherapy between January 2016 and December 2017 were identified from the database of the Affiliated Hospital of Qingdao University. The primary end point was progression-free survival (PFS).

Results

The study included 135 MBC patients who were treated with fulvestrant; 116 patients who received fulvestrant as first-line treatment were divided into 2 groups: the no-chemotherapy treatment (NCT) group received fulvestrant as initial therapy during disease progression, and the chemotherapy treatment (CT) group received fulvestrant as maintenance following disease stabilization or response to previous chemotherapy. The median PFS was 16 months in NCT patients and 8 months in the CT group. Patients who had a longer disease-free survival, no visceral metastasis and one metastasis site, benefited from fulvestrant as first-line treatment during disease progression. Patients with 2 or more metastasis sites benefited from chemotherapy as first-line treatment and fulvestrant as maintenance treatment.

Conclusions

Fulvestrant monotherapy showed good clinical activity and safety in patients with MBC who were treated upon disease progression and in those receiving maintenance therapy.

Nuclear Mechanisms Involved in Endocrine Resistance

Endocrine therapy is a standard treatment offered to patients with ERα (estrogen receptor α)-positive breast cancer. In endocrine therapy, ERα is either directly targeted by anti-estrogens or indirectly by aromatase inhibitors which cause estrogen deficiency. Resistance to these drugs (endocrine resistance) compromises the efficiency of this treatment and requires additional measures. Endocrine resistance is often caused by deregulation of the PI3K/AKT/mTOR pathway and/or cyclin-dependent kinase 4 and 6 activities allowing inhibitors of these factors to be used clinically to counteract endocrine resistance. The nuclear mechanisms involved in endocrine resistance are beginning to emerge. Exploring these mechanisms may reveal additional druggable targets, which could help to further improve patients' outcome in an endocrine resistance setting. This review intends to summarize our current knowledge on the nuclear mechanisms linked to endocrine resistance.

lncRNA and breast cancer: Progress from identifying mechanisms to challenges and opportunities of clinical treatment

Breast cancer is a malignant tumor that has a high mortality rate and mostly occurs in women. Although significant progress has been made in the implementation of personalized treatment strategies for molecular subtypes in breast cancer, the therapeutic response is often not satisfactory. Studies have reported that long non-coding RNAs (lncRNAs) are abnormally expressed in breast cancer and closely related to the occurrence and development of breast cancer. In addition, the high tissue and cell-type specificity makes lncRNAs particularly attractive as diagnostic biomarkers, prognostic factors, and specific therapeutic targets. Therefore, an in-depth understanding of the regulatory mechanisms of lncRNAs in breast cancer is essential for developing new treatment strategies. In this review, we systematically elucidate the general characteristics, potential mechanisms, and targeted therapy of lncRNAs and discuss the emerging functions of lncRNAs in breast cancer. Additionally, we also highlight the advantages and challenges of using lncRNAs as biomarkers for diagnosis or therapeutic targets for drug resistance in breast cancer and present future perspectives in clinical practice.

Efficacy and safety of CDK4/6 and PI3K/AKT/mTOR inhibitors as second-line treatment in postmenopausal patients with hormone receptor-positive, HER-2-negative metastatic breast cancer: a network meta-analysis

BACKGROUND

We compared the efficacy and safety of combinations of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors and PI3K/AKT/mTOR inhibitors as second-line treatment in postmenopausal women with HR⁺, HER2^- metastatic breast cancer.

METHODS

We searched the Medline, Embase, and Cochrane Library electronic databases for phase II/III randomized trials evaluating CDK4/6 and PI3K/AKT/mTOR inhibitors plus fulvestrant. We compared the results with a network meta-analysis. Study quality was assessed following the GRADE approach. Outcomes of interest were progression-free survival, overall response rate, overall survival and G3-4 adverse drug events (ADEs).

RESULTS

Eight RCTs were identified in the network meta-analysis. PFS was significantly improved by treatment with abemaciclib plus fulvestrant and ribociclib plus fulvestrant compared to pictilisib plus fulvestrant. The ORR following treatment with abemaciclib plus fulvestrant, ribociclib plus fulvestrant, palbociclib plus fulvestrant, buparlisib plus fulvestrant, and alpelisib plus fulvestrant significantly differed from that observed following treatment with placebo plus fulvestrant. In terms of OS, compared with placebo plus fulvestrant, abemaciclib plus fulvestrant, ribociclib plus fulvestrant, and buparlisib plus fulvestrant had a significant difference. The risks of ADEs were similar among three CDK4/6 inhibitors.

CONCLUSION

As second-line treatment, three CDK4/6 inhibitors showed superior clinical efficacy compared to other PI3K/AKT/mTOR inhibitors with comparable safety profiles.

From Micro to Long: Non-Coding RNAs in Tamoxifen Resistance of Breast Cancer Cells

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer mortality among women. Two thirds of patients are classified as hormone receptor positive, based on expression of estrogen receptor alpha (ERα), the main driver of breast cancer cell proliferation, and/or progesterone receptor, which is regulated by ERα. Despite presenting the best prognosis, these tumors can recur when patients acquire resistance to treatment by aromatase inhibitors or antiestrogen such as tamoxifen (Tam). The mechanisms that are involved in Tam resistance are complex and involve multiple signaling pathways. Recently, roles for microRNAs and lncRNAs in controlling ER expression and/or tamoxifen action have been described, but the underlying mechanisms are still little explored. In this review, we will discuss the current state of knowledge on the roles of microRNAs and lncRNAs in the main mechanisms of tamoxifen resistance in hormone receptor positive breast cancer. In the future, this knowledge can be used to identify patients at a greater risk of relapse due to the expression patterns of ncRNAs that impact response to Tam, in order to guide their treatment more efficiently and possibly to design therapeutic strategies to bypass mechanisms of resistance.

Mechanisms of endocrine therapy resistance in breast cancer

The most commonly diagnosed breast cancer (BC) subtype is characterized by estrogen receptor (ER) expression. Treatment of this BC subtype typically involves modalities that either suppress the production of estrogen or impede the binding of estrgen to its receptors, constituting the basis for endocrine therapy. While many patients have benefitted from endocrine therapy with clear reduction in mortality and cancer recurrence, one of the clinical hurdles that remain involves overcoming intrinsic (de novo) or acquired resistance to endocrine therapy driven by diverse and complex changes occurring in the tumor microenvironment. Moreover, such resistance may persist even after progression through additional antiestrogen therapies thus demonstrating the importance of further investigation of mechanisms of ER modulation. Here, we discuss a number of advances that provide a better understanding of the complex mechanistic basis for resistance to endocrine therapy as well as future therapeutic maneuvers that may break this resistance.

Non-Small Cell Lung Cancer Harboring Concurrent EGFR Genomic Alterations: A Systematic Review and Critical Appraisal of the Double Dilemma

The molecular pathways which promote lung cancer cell features have been broadly explored, leading to significant improvement in prognostic and diagnostic strategies. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have dramatically altered the treatment approach for patients with metastatic non-small cell lung cancer (NSCLC). Latest investigations by using next-generation sequencing (NGS) have shown that other oncogenic driver mutations, believed mutually exclusive for decades, could coexist in EGFR-mutated NSCLC patients. However, the exact clinical and pathological role of concomitant genomic aberrations needs to be investigated. In this systematic review, we aimed to summarize the recent data on the oncogenic role of concurrent genomic alterations, by specifically evaluating the characteristics, the pathological significance, and their potential impact on the treatment approach.

SOX12 expression is associated with progression and poor prognosis in human breast cancer

The sex-determining region Y-box 12 (SOX12) is implicated in several oncogenic signaling pathways of multiple types of cancer; however, the biological effects of SOX12 on breast cancer has yet to be elucidated. Here, we assessed SOX12 expression using real-time quantitative PCR in 142 pairs of breast cancer and adjacent normal tissues (ANTs) and immunohistochemistry in 524 breast cancer and 147 ANTs. The effects of SOX12 on breast cancer progression, clinicopathological variables, and prognostic value were then investigated. SOX12 expression was markedly elevated in breast cancer tissues relative to that in ANTs at both mRNA and protein levels. Positive SOX12 expression was correlated to tumor size (P = 0.005), estrogen receptor (ER) (P = 0.018) and human epidermal growth factor receptor (HER2) (P = 0.004) status, lymph node metastasis (P < 0.001), and the tumor-node-metastasis (TNM) stage (P < 0.001). Notably, the positive rate of SOX12 expression gradually increased with breast cancer progression. Multivariate analysis indicated that SOX12 was an independent prognostic factor for overall survival (OS, P = 0.023) and distant metastasis-free survival (DMFS, P = 0.012). Subgroup analysis revealed that luminal and HER2 patients with positive SOX12 expression had a shorter OS period than those with negative SOX12 expression. Moreover, SOX12 expression was associated with a high risk of distant metastasis in invasive carcinoma with the lymph node metastasis subgroup. In summary, SOX12 correlates with progression and poor prognosis in human breast cancer, suggesting that SOX12 is a potential target for breast cancer treatment and warrants further functional research.

Therapy options after CDK4/6 inhibitors for HR+, HER2- postmenopausal metastatic/recurrent breast cancer in Japan: a role for mammalian target of rapamycin inhibitors?

Despite advances in the treatment of hormone receptor-positive, HER2- metastatic breast cancer, the disease is rarely curable. In this review, we focus on the use of CDK4/6 inhibitors, examining clinical experience and the mechanisms underlying the development of resistance, and evaluating treatment options after failure to respond to CDK4/6 inhibitors. Current basic research supports the use of mammalian target of rapamycin inhibitors after CDK4/6 inhibitor failure; however, more data are needed, particularly regarding treatment sequencing. Real-world data studies may help to fill the current knowledge gap, particularly where large-scale randomized controlled studies are not feasible.

Efficacy of Palbociclib and Endocrine Treatment in Heavily Pretreated Hormone Receptor-positive/HER2-negative Advanced Breast Cancer: Retrospective Multicenter Trial

Background:

The synthesis of CDK4/6 inhibitors with endocrine treatment in two series of treatment has been widely accepted as the standard for patients with estrogen receptor-positive metastatic breast cancer. In spite of this, the activity of CDK4/6 inhibitors in patients with metastatic breast cancer who have progressed despite receiving multiple lines of treatment is not well understood.

Aims:

To report the activity and safety of a CDK4/6 inhibitor (palbociclib) in patients in whom at least three lines of treatment for ER+ metastatic breast cancer had failed.

Study Design:

Multicenter retrospective observational cohort study.

Methods:

In this retrospective observational cohort study, we included 43 patients who received palbociclib after at least three lines of systemic treatment for ER+/HER2− metastatic breast cancer.

Results:

The median progression-free survival in our population was 7 months (25^th-75^th percentile, 4-10), and the median overall survival was 11 months (25^th-75^th percentile, 6-19). Although there were some adverse events, palbociclib was generally well tolerated, so dose reduction was needed for only six patients (14%).

Conclusion:

The efficacy of palbociclib among heavily treated hormone receptor-positive/HER2− patients with advanced breast cancer was acceptable in terms of clinical benefit, and it was generally well tolerated among this population.

Patterns of treatment and outcome with 500-mg fulvestrant in postmenopausal women with hormone receptor-positive/HER2-negative metastatic breast cancer: a real-life multicenter Italian experience

Background:

Fulvestrant 500 mg (F500) is the most active endocrine single agent in hormone receptor-positive (HR+)/HER2-negative metastatic breast cancer (MBC). Few data are available regarding the effectiveness of the drug in a real-world setting.

Patients and methods:

This prospective, multicenter cohort study aimed to describe the patterns of treatment and performance of F500 in a large population of unselected women with MBC, focusing on potential prognostic or predictive factors for disease outcome and response. The primary endpoints were progression-free survival (PFS) and clinical benefit rate.

Results:

From January 2011 to December 2015, 490 consecutive patients treated with F500 were enrolled. Overall, three different cohorts were identified and analyzed: the first received F500 after progression from previous chemotherapy (CT) or endocrine therapy; the second received the drug for de novo metastatic disease; and the third was treated as maintenance following disease stabilization or a response from a previous CT line. Median overall survival (OS) in the whole population was 26.8 months, ranging from 32.4 in first line to 22.0 and 13.7 months in second line and subsequent lines, respectively. Both the presence of liver metastasis and the treatment line were significantly associated with a worse PFS, while only the presence of liver metastasis maintained its predictive role for OS in multivariate analysis.

Conclusions:

The effectiveness of F500 was detected in patients treated both upon disease progression and as maintenance. The relevant endocrine sensitivity of 80% of patients included in the study could probably explain the good results observed in terms of outcome.

Anti-Wrinkling and Anti-Melanogenic Effect of Pradosia mutisii Methanol Extract

Ultraviolet (UV) exposure causes skin photoaging leading to skin wrinkling and sagging via production of reactive oxygen species (ROS). For this reason, protection from photoaging is an important feature in cosmeceutical and dermatological products. Natural product-derived biomaterials are highly desired as future possible ingredients, because these biomaterials are often safe and effective. In this study, we aimed to characterize the skin protective activity of Pradosia mutisii, traditionally used to treat sunburn and erythema. We determined the free radical scavenging, anti-melanogenic, and moisturizing effects of a methanol extract of Pradosia mutisii (Pm-ME) in keratinocytes (HaCaT cells), melanocytes (B16F10 cells), and fibroblasts (human dermal fibroblasts (HDFs)) at non-cytotoxic concentrations. Pradosia mutisii methanol extract contains coumaric acid as a major component, and the extract exhibited protective activity against UVB- and H₂O₂-induced cytotoxicity. This extract also suppressed the expression of metalloproteinases (MMPs) and cyclooxygenase (COX)-2 in HaCaT cells. A reduction of Sirt-1 expression under UVB- and H₂O₂-treated conditions was recovered in HaCaT cells by Pm-ME. This extract displayed significant free radical scavenging activity according to the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) assay. The Pm-ME also upregulated the expression levels of hyaluronic acid synthase (HAS) and transglutaminase-1 (TGM-1) in HaCaT cells, indicating a putative moisturizing activity. Interestingly, the expression of collagen type 1 (Col1A1) gene and its promoter activity, as assessed by a reporter gene assay, were found to be increased in HDF and HEK293 cells. Similarly, Pm-ME helped recover collagen levels after UVB and H₂O₂ treatment in HDFs as well as decreased the synthesis and secretion of melanin from B16F10 melanoma cells, which may indicate a beneficial whitening cosmetic value. The p38 inhibitor SB203580 and the JNK inhibitor SP600125 suppressed MMP-9 and COX-2 expression in H₂O₂-treated HaCaT cells. Similarly, the ERK inhibitor U0126 inhibited HAS-2 in Pm-ME/H₂O₂-treated HaCaT cells. These findings suggested that inhibition of JNK and p38 and activation of ERK could be targeted by Pm-ME. Therefore, Pm-ME may exert anti-photoaging and anti-melanogenic properties via the regulation of mitogen-activated protein kinase, which could be beneficial in the cosmeceutical industry.

Compound K, a ginsenoside metabolite, plays an antiinflammatory role in macrophages by targeting the AKT1-mediated signaling pathway

Background

Compound K (CK) is an active metabolite of ginseng saponin, ginsenoside Rb1, that has been shown to have ameliorative properties in various diseases. However, its role in inflammation and the underlying mechanisms are poorly understood. In this report, the antiinflammatory role of CK was investigated in macrophage-like cells.

Methods

The CK-mediated antiinflammatory mechanism was explored in RAW264.7 and HEK293 cells that were activated by lipopolysaccharide (LPS) or exhibited overexpression of known activation proteins. The mRNA levels of inflammatory genes and the activation levels of target proteins were identified by quantitative and semiquantitative reverse transcription polymerase chain reaction and Western blot analysis.

Results

CK significantly inhibited the mRNA expression of inducible nitric oxide synthase and tumor necrosis factor-α and morphological changes in LPS-activated RAW264.7 cells under noncytotoxic concentrations. CK downregulated the phosphorylation of AKT1, but not AKT2, in LPS-activated RAW264.7 cells. Similarly, CK reduced the AKT1 overexpression-induced expression of aldehyde oxidase 1, interleukin-1β, interferon-β, and tumor necrosis factor-α in a dose-dependent manner.

Conclusion

Our results suggest that CK plays an antiinflammatory role during macrophage-mediated inflammatory actions by specifically targeting the AKT1-mediated signaling pathway.

Study on Biological Characteristics and Mechanism of Paclitaxel Induced Drug Resistance in Endometrial Carcinoma Cells

Objective

To study the biological characteristics of paclitaxel resistant endometrial carcinoma cells and its mechanism of drug resistance.

Method

The paclitaxel resistant cell lines were established by high-dose paclitaxel (TAX) injection. The IC50 of paclitaxel was determined by CCK-8 assay in Ishikawa and Ishikawa-TAX. The cell cycle and apoptosis rate were detected by flow cytometry. Western blot was used to detect the expression of p-AKT and p-p70S6K. The expression of drug resistance-related genes Pgp and MDR1 was determined by RT-PCR. Cell viability was determined by soft agarose assay and invasive ability in vitro by transwell assay.

Results

Paclitaxel and NVP-BEZ235 cotreatment group can further inhibit the clonogenicity and invasion of Ishikawa and Ishikawa-TAX cells compared with paclitaxel alone and NVP-BEZ235 treatment group. Paclitaxel and NVP-BEZ235 cotreated groups increased the apoptosis rate of Ishikawa and increased G0/G1 phase arrest in both cells. Paclitaxel alone significantly inhibited p-AK and p-p70 S6K protein expression in Ishikawa and Ishikawa-TAX cells and the inhibition was enhanced by NVP-BEZ235 when cotreated with paclitaxel.

Conclusion

Paclitaxel can inhibit Ishikawa and Ishikawa-TAX cell via PI3K/Akt/mTOR signaling pathway. Paclitaxel and NVP-BEZ235 cotreatment can enhance the inhibitory effect.

CDK4/6 inhibitors in breast cancer therapy: Current practice and future opportunities

Dysregulation of the cyclin dependent kinase pathway in luminal breast cancer creates a new therapeutic opportunity for estrogen receptor positive breast cancer. Initial pan-CDK inhibitors were associated with extensive toxicities but in recent years, the development of potent specific CDK inhibitors with favorable tolerability has driven renewed interests in this class of targeted therapies. Palbociclib, ribociclib and abemaciclib are specific CDK4/6 inhibitors that have been approved by the U.S. Food and Drug Administration for use in combination with endocrine therapy for women with advanced hormone receptor positive breast cancer. These three anticancer therapeutics were approved based on progression free survival benefit seen on phase III trials with the most common grade 3 treatment-related side effects being neutropenia, fatigue, nausea and diarrhea. Except for estrogen receptor positivity, no biomarkers predictive of response to CDK4/6 inhibitors have been identified to date. Based on mechanistic insights here described, CDK4/6 inhibitors are currently being explored in combination with other agents, including targeted therapies, immunotherapy and chemotherapy.

Overcoming endocrine resistance in metastatic hormone receptor-positive breast cancer

Endocrine therapy has historically formed the basis of treatment of metastatic hormone receptor-positive breast cancer. The development of endocrine resistance has led to the development of newer endocrine drug combinations. Use of the CDK4/6 inhibitors has significantly improved progression-free survival in this group of patients. There are multiple studies of the use of P13K inhibitors and mTOR inhibitors for use as subsequent lines of therapy, particularly for endocrine resistance. The optimal sequencing of therapy should be based on medical comorbidities, prior adjuvant therapies, quality of life, side-effect profile, and disease-free interval.

Structural underpinnings of oestrogen receptor mutations in endocrine therapy resistance

Oestrogen receptor-α (ERα), a key driver of breast cancer, normally requires oestrogen for activation. Mutations that constitutively activate ERα without the need for hormone binding are frequently found in endocrine-therapy-resistant breast cancer metastases and are associated with poor patient outcomes. The location of these mutations in the ER ligand-binding domain and their impact on receptor conformation suggest that they subvert distinct mechanisms that normally maintain the low basal state of wild-type ERα in the absence of hormone. Such mutations provide opportunities to probe fundamental issues underlying ligand-mediated control of ERα activity. Instructive contrasts between these ERα mutations and those that arise in the androgen receptor (AR) during anti-androgen treatment of prostate cancer highlight differences in how activation functions in ERs and AR control receptor activity, how hormonal pressures (deprivation versus antagonism) drive the selection of phenotypically different mutants, how altered protein conformations can reduce antagonist potency and how altered ligand-receptor contacts can invert the response that a receptor has to an agonist ligand versus an antagonist ligand. A deeper understanding of how ligand regulation of receptor conformation is linked to receptor function offers a conceptual framework for developing new anti-oestrogens that might be more effective in preventing and treating breast cancer.

Palbociclib in highly pretreated metastatic ER-positive HER2-negative breast cancer

PURPOSE

We aimed to investigate the role of palbociclib, a first-in-class cyclin-dependent kinase 4 and 6 inhibitor, in postmenopausal women with highly pretreated endocrine therapy-resistant metastatic breast cancer (MBC).

METHODS

Between 28 September 2015 and 14 March 2017, a compassionate use program was established in the University Hospitals Leuven in which 82 postmenopausal women with estrogen receptor-positive, HER2-negative MBC were included after at least four lines of systemic treatment. The efficacy and safety analysis was performed in 82 patients who had received at least one dose of palbociclib and who had at least 6-month follow-up at the data cut-off point. The primary objective was the evaluation of efficacy of the combination of palbociclib and endocrine therapy with clinical benefit as primary endpoint, defined as the absence of progressive disease and being on treatment for at least 6 months. Secondary objectives were the evaluation of toxicity and the identification of potential predictors for clinical benefit.

RESULTS

The median age of the patients was 67.1 years (range 34.8-85.9) at the time of inclusion. The average duration of treatment was 5.6 months (range 1-19), with a median progression-free survival of 3.17 (95% CI 2.76-4.70) months. At the data cut-off point, 10 patients were still on treatment with palbociclib. In this highly pretreated setting, 34 patients experienced no progressive disease within 6 months, resulting in an overall clinical benefit rate (CBR) of 41.5%. 20.7% (17/82) showed stable disease for ≥ 9 months and 13.4% for ≥ 12 months. None of the investigated predicting factors were significantly associated with clinical benefit at 6 months. For 43.9% of the patients, treatment delay or dose reduction was indicated.

CONCLUSIONS

Palbociclib in combination with endocrine therapy shows an unexpectedly high CBR and favorable safety profile in heavily pretreated endocrine-resistant estrogen receptor-positive, HER2-negative MBC patients.

Hydroquinone Exhibits In Vitro and In Vivo Anti-Cancer Activity in Cancer Cells and Mice

Hydroquinone (HQ, 1,4-benzenediol) is a hydroxylated benzene metabolite with various biological activities, including anti-oxidative, neuroprotective, immunomodulatory, and anti-inflammatory functions. However, the anti-cancer activity of HQ is not well understood. In this study, the in vitro and in vivo anti-cancer activity of HQ was investigated in various cancer cells and tumor-bearing mouse models. HQ significantly induced the death of A431, SYF, B16F10, and MDA-MB-231 cells and also showed a synergistic effect on A431 cell death with other anti-cancer agents, such as adenosine-2′,3′-dialdehyde and buthionine sulfoximine. In addition, HQ suppressed angiogenesis in fertilized chicken embryos. Moreover, HQ prevented lung metastasis of melanoma cells in mice in a dose-dependent manner without toxicity and adverse effects. HQ (10 mg/kg) also suppressed the generation of colon and reduced the thickness of colon tissues in azoxymethane/dextran sodium sulfate-injected mice. This study strongly suggests that HQ possesses in vitro and in vivo anti-cancer activity and provides evidence that HQ could be developed as an effective and safe anti-cancer drug.

Efficacy of palbociclib plus fulvestrant after everolimus in hormone receptor-positive metastatic breast cancer

BACKGROUND

Palbociclib, a CDK4-6 inhibitor, combined with endocrine therapy (ET) is a new standard of treatment for Hormone Receptor-positive Metastatic Breast Cancer. We present the first real-life efficacy and tolerance data of palbociclib plus fulvestrant in this population.

METHODS

From November 2015 to November 2016, patients receiving in our institution palbociclib + fulvestrant according to the Temporary Authorization for Use were prospectively analyzed.

RESULTS

60 patients were treated accordingly; median age was 61 years; 50 patients (83.3%) had visceral metastasis, and 10 (16.7%) had bone-only disease. Patients had previously received a median of 5 (1-14) lines of treatment, including ET (median 3) and chemotherapy (median 2); 28 (46.7%) received previously fulvestrant and all everolimus. With a median follow-up of 10.3 months, median progression-free survival (mPFS) was 5.8 months (95% CI 3.9-7.3). Patients pretreated with fulvestrant had a similar PFS of 6.4 months (HR 1.00; 95% CI 0.55-1.83; P = 1.00). The most common AEs (adverse events) were neutropenia (93%), anemia (65%), and thrombocytopenia (55%).

CONCLUSION

In this heavily pretreated population including everolimus, fulvestrant plus palbociclib provides an mPFS of 5.8 months with the same magnitude of benefit for fulvestrant-pretreated patients.

PI3K/mTOR Inhibitors in the Treatment of Luminal Breast Cancer. Why, When and to Whom?

Estrogen receptor (ER) signaling represents the main driver of tumor growth and survival in luminal breast cancer (BC). Despite the efficacy of endocrine agents, many patients with luminal BC do not respond to endocrine therapy and many others develop endocrine resistance over time, due to the activation of escape pathways such as the PI3K/AKT/mTOR signaling. Several clinical trials have demonstrated the efficacy of mTOR and PI3K inhibitors in overcoming endocrine resistance in hormone receptor-positive human epidermal growth factor receptor 2 (HER2)-negative metastatic BC (MBC) patients. Nevertheless, to date, everolimus is the only agent targeting the PI3K/mTOR pathway that has been approved for clinical use. Recently, the introduction of CDK 4/6 inhibitors into clinical practice has significantly changed the therapeutic scenarios in luminal MBC. In the absence of direct comparisons among the new treatment combinations and predictive biomarkers of response, the choice of optimal therapeutic algorithms is very challenging. Future trials should focus on identifying more effective and safe combination therapies and defining the best treatment sequences in luminal BC.