Randomized Phase II Trial of Fulvestrant Plus Everolimus or Placebo in Postmenopausal Women With Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Metastatic Breast Cancer Resistant to Aromatase Inhibitor Therapy: Results of PrE0102

Comparison of mTOR inhibitors combined with endocrine therapy versus that alone in breast cancer: a meta-analysis

BACKGROUND

This meta-analysis aims to evaluate the efficacy and safety of rapamycin (mTOR) inhibitors with endocrine therapy versus endocrine therapy alone in treating advanced or metastatic estrogen receptor/progesterone receptor (ER/PR) + breast cancer.

METHODS

We conducted a comprehensive search in PubMed, Web of Science, Embase, and the Cochrane Library for randomized controlled trials (RCTs) comparing mTOR inhibitors plus endocrine therapy with endocrine therapy alone up to September 2024.

RESULTS

This analysis included 10 RCTs comprising 3,337 patients. Relative to endocrine therapy alone, the combination of mTOR inhibitors and endocrine therapy significantly improved the clinical benefit rate (RR = 1.41, p < 0.001), overall response rate (RR = 1.40, p = 0.006), progression-free survival (PFS; HR = 0.67, p < 0.001), and overall survival (OS; HR = 0.86, p = 0.056), although the improvement in OS was not statistically significant. Subgroup analyses indicated a more pronounced PFS advantage in patients under 65 years of age (HR = 0.55, p = 0.013) and those who had previously received chemotherapy (HR = 0.51, p = 0.001). However, the incidence of adverse events was higher in the combination therapy group, notably stomatitis (p < 0.001), elevated aspartate aminotransferase/alanine aminotransferase (p = 0.04), and diarrhea (p = 0.01).

CONCLUSIONS

The combination of mTOR inhibitors with endocrine therapy offers superior efficacy with manageable toxicities in patients with advanced or metastatic ER/PR+ breast cancer.

Differential benefit of adjuvant everolimus according to endocrine therapy backbone in the randomized UNIRAD trial

BACKGROUND

The randomized, double-blind UNIRAD trial evaluating the addition of 2 years of everolimus to endocrine therapy in patients with high-risk, early luminal breast cancer failed to demonstrate a benefit. We report the subgroup analyses.

PATIENTS AND METHODS

We randomly assigned 1278 patients in a 1 : 1 ratio to receive 2 years of placebo or everolimus, added to endocrine therapy for up to 4 years after initiation. Randomization was stratified by endocrine therapy agent, prior adjuvant versus neoadjuvant therapy, progesterone receptor expression, and lymph node involvement. Subgroup analyses by each stratification factor were pre-specified. Post hoc analyses were carried out according to menopausal status and age. Treatment adherence was also analyzed.

RESULTS

We observed a limited trend toward more favorable prognostic features in tamoxifen-treated patients, with more frequent estrogen receptor-positive/progesterone receptor-positive tumors (88.5% versus 84.1%, P = 0.026) and less frequent pN2-positive status (39.8% versus 46.0%, P = 0.032). In premenopausal women, we observed a numerical benefit of everolimus: 3-year disease-free survival was 86% in the placebo group and 90% in the everolimus group (hazard ratio 0.76, 95% confidence interval 0.43-1.34). In premenopausal patients treated with tamoxifen (n = 153; 12.3%), we observed an even stronger trend in favor of everolimus as 3-year DFS was 84% in the placebo group and 91% in the everolimus group (hazard ratio 0.54, 95% confidence interval 0.28-1.02). Early discontinuation of either everolimus or placebo was less frequent in the tamoxifen group than in the aromatase inhibitor group: 48.0% versus 56.9% (P = 0.028).

CONCLUSIONS

The present post hoc analyses generate hypotheses regarding the interaction between menopausal status, tamoxifen, and everolimus in patients with high-risk, ER-positive, human epidermal growth factor receptor type 2-negative early breast cancer. They suggest that tamoxifen alone is an underpowered endocrine treatment in high-risk premenopausal patients.

Molecular Mechanisms and Therapeutic Strategies to Overcome Resistance to Endocrine Therapy and CDK4/6 Inhibitors in Advanced ER+/HER2- Breast Cancer

Approximately 70-80% of breast cancers are estrogen receptor-positive (ER+), with 65% of these cases also being progesterone receptor-positive (ER+PR+). In most cases of ER+ advanced breast cancer, endocrine therapy (ET) serves as the first-line treatment, utilizing various drugs that inhibit ER signaling. These include tamoxifen, a selective estrogen receptor modulator (SERM); fulvestrant, a selective estrogen receptor degrader (SERD); and aromatase inhibitors (AIs), which block estrogen synthesis. However, intrinsic or acquired hormone resistance eventually develops, leading to disease progression. The combination of ET with cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6is) has been shown to significantly increase progression-free survival (PFS) and, in some cases, overall survival (OS). CDK4/6is works by arresting the cell cycle in the G1 phase, preventing DNA synthesis, and enhancing the efficacy of ET. This review highlights the key mechanisms of resistance to ET, whether used alone or in combination with biological agents, as well as emerging therapeutic strategies aimed at overcoming resistance. Addressing ET resistance remains a work in progress, and in the near future, better patient selection for different therapeutic approaches is expected through the identification of more precise biological and genetic markers. In particular, liquid biopsy may provide a real-time portrait of the disease, offering insights into mechanisms driving ET resistance and cancer progression.

Novel Estrogen Receptor - Targeted Therapies in Hormone-Receptor Positive Breast Cancer

OPINION STATEMENT

Endocrine therapy is the backbone of treatment for HR + /HER2- MBC. The introduction of novel endocrine-based therapies has changed the landscape of metastatic breast cancer care, with even more promising agents on the horizon. Given the consistent success in prolonging PFS and OS, CDK4/6 inhibitors should be used as first-line treatment. Once secondary resistance eventually develops after use of a CDK4/6 inhibitor, use of monotherapy with either AI or fulvestrant has shown poor outcome. For example, in the control group of the EMERALD trial, in which all the patients were required to have previously received a CDK4/6 inhibitor, median progression-free survival with endocrine therapy was only 1.9 months. Based on the emerging evidence, molecular profiling of tissue or liquid biopsy at progression of disease is crucial to select future therapy. For patients whose tumors harbor ESR1 mutations, oral SERDs are the preferred option. For those with PIK3CA or AKT1 mutation or PTEN inactivation, combination therapy with the AKT pathway inhibitor capivasertib is recommended. Alpelisib, the first AKT1 inhibitor approved in combination therapy with fulvestrant in PIK3CA mutated tumors only, is now less in favor given its challenging side effect profile. When mutations are not present, options include combination therapy with the mTOR inhibitor everolimus or changing endocrine therapy and continuing a CDK 4/6 inhibitor. In patients with short response to CDK4/6 inhibitors suggesting endocrine resistant disease, chemotherapy or antibody-drug conjugates should be considered. With better understanding of the mechanisms of resistance to CDK4/6 inhibitors, additional mutations could be identified and potentially targeted in order to provide individualized treatment options. Optimal sequencing of treatment options depends on several factors: (1) the presence of specific molecular aberrations; (2) previous treatment history, duration of response and patient's performance status; (3) balance between maximizing survival benefits with quality of life/toxicities; (4) disease burden. In the upcoming years, we anticipate FDA approvals for more of the SERD molecules both in monotherapy and in combination therapy which will continue to expand the options available for HR + /HER2- MBC patients.

Post-progression treatment options after CDK4/6 inhibitors in hormone receptor-positive, HER2-negative metastatic breast cancer

The combination of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) and endocrine therapy (ET) is the standard first-line treatment for hormone receptor-positive (HR + ) and HER2-negative metastatic breast cancer (mBC). Despite their efficacy, resistance inevitably develops, necessitating alternative therapeutic strategies post-progression. This review explores current and emerging treatment options following progression on CDK4/6i, focusing on endocrine therapies, targeted therapies, combination approaches, and the continued use of CDK4/6i. Endocrine therapies, including fulvestrant and novel oral selective estrogen receptor degraders (SERDs) like elacestrant, show promise, especially in patients with ESR1 mutations. Targeted therapies such as PI3K/AKT/mTOR inhibitors, exemplified by alpelisib and capivasertib, offer potential by addressing downstream signaling pathways involved in resistance. Additionally, FGFR inhibitors like erdafitinib are under investigation for their role in overcoming specific resistance mechanisms. Combination strategies involving CDK4/6 inhibitors with immune checkpoint inhibitors or other targeted agents are also being explored, with early trials suggesting possible synergistic effects, although further validation is required. Continuation of CDK4/6 inhibitors beyond progression has shown potential benefits in selected patients, but the data are heterogeneous, and further studies are needed to clarify their role. While chemotherapy remains a standard option for patients who progress on these treatments, the goal is to delay its use through the effective utilization of endocrine and targeted therapies. Understanding resistance mechanisms and tailoring treatment to individual patient profiles is crucial for optimizing outcomes. Ongoing clinical trials are expected to provide deeper insights, guiding the development of more effective post-progression therapeutic strategies. This evolving landscape highlights the need for continuous research and individualized patient care to improve survival and quality of life in HR + mBC patients.

Efficiency of Fulvestrant Monotherapy After CDK4/6 Inhibitor Exposure: Is This a Viable Choice?

Guidelines for the first-line treatment of Hormone Receptor-positive, HER2-negative advanced or recurrent breast cancer have shifted to combination therapies of a CDK4/6 inhibitor and endocrine therapy. However, determining an optimal subsequent therapy following CDK4/6 inhibitor progression remains challenging, especially for tumors lacking actionable mutations. Real-world data suggest that fulvestrant monotherapy is frequently selected in this post-CDK4/6 inhibitor setting. This review examines its therapeutic potential in this evolving landscape. A systematic literature search using PubMed and ClinicalTrials.gov identified 153 clinical trials published between 2017 and November 2024, from which ten studies met our strict inclusion criteria, focusing solely on fulvestrant monotherapy. These trials encompassed 1038 patients who had prior exposure to CDK4/6 inhibitors. The selected studies were categorized into three groups: monotherapy trials (EMERALD, SERENA-2, AMEERA-3, and ELAINE-1), combination therapy trials (CAPItello-291 and VERONICA), and CDK4/6 inhibitor rechallenge trials (post-MONARCH, PACE, PALMIRA, and MAINTAIN). The median progression-free survival for fulvestrant monotherapy was 3.18 months (range 1.9-5.3 months). Factors affecting the efficacy of fulvestrant monotherapy in second-line therapy include prior treatments, treatment duration, and genetic mutations. Given that the efficacy of fulvestrant was short-lived in the second or subsequent lines, participating in clinical trials is a vital option until a novel alternative treatment choice becomes available.

Breast cancer: pathogenesis and treatments

Breast cancer, characterized by unique epidemiological patterns and significant heterogeneity, remains one of the leading causes of malignancy-related deaths in women. The increasingly nuanced molecular subtypes of breast cancer have enhanced the comprehension and precision treatment of this disease. The mechanisms of tumorigenesis and progression of breast cancer have been central to scientific research, with investigations spanning various perspectives such as tumor stemness, intra-tumoral microbiota, and circadian rhythms. Technological advancements, particularly those integrated with artificial intelligence, have significantly improved the accuracy of breast cancer detection and diagnosis. The emergence of novel therapeutic concepts and drugs represents a paradigm shift towards personalized medicine. Evidence suggests that optimal diagnosis and treatment models tailored to individual patient risk and expected subtypes are crucial, supporting the era of precision oncology for breast cancer. Despite the rapid advancements in oncology and the increasing emphasis on the clinical precision treatment of breast cancer, a comprehensive update and summary of the panoramic knowledge related to this disease are needed. In this review, we provide a thorough overview of the global status of breast cancer, including its epidemiology, risk factors, pathophysiology, and molecular subtyping. Additionally, we elaborate on the latest research into mechanisms contributing to breast cancer progression, emerging treatment strategies, and long-term patient management. This review offers valuable insights into the latest advancements in Breast Cancer Research, thereby facilitating future progress in both basic research and clinical application.

Canonical and noncanonical NOTCH signaling in the nongenetic resistance of cancer: distinct and concerted control

Therapeutic resistance in cancer is responsible for numerous cancer deaths in clinical practice. While target mutations are well recognized as the basis of genetic resistance to targeted therapy, nontarget mutation resistance (or nongenetic resistance) remains poorly characterized. Despite its complex and unintegrated mechanisms in the literature, nongenetic resistance is considered from our perspective to be a collective response of innate or acquired resistant subpopulations in heterogeneous tumors to therapy. These subpopulations, e.g., cancer stem-like cells, cancer cells with epithelial-to-mesenchymal transition, and drug-tolerant persisters, are protected by their resistance traits at cellular and molecular levels. This review summarizes recent advances in the research on resistant populations and their resistance traits. NOTCH signaling, as a central regulator of nongenetic resistance, is discussed with a special focus on its canonical maintenance of resistant cancer cells and noncanonical regulation of their resistance traits. This novel view of canonical and noncanonical NOTCH signaling pathways is translated into our proposal of reshaping therapeutic strategies targeting NOTCH signaling in resistant cancer cells. We hope that this review will lead researchers to study the canonical and noncanonical arms of NOTCH signaling as an integrated resistant mechanism, thus promoting the development of innovative therapeutic strategies.

Imlunestrant, an Oral Selective Estrogen Receptor Degrader, as Monotherapy and in Combination With Targeted Therapy in Estrogen Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: Phase Ia/Ib EMBER Study

PURPOSE

Imlunestrant is a next-generation oral selective estrogen receptor (ER) degrader designed to deliver continuous ER target inhibition, including in ESR1-mutant breast cancer. This phase Ia/b trial determined the recommended phase II dose (RP2D), safety, pharmacokinetics, and efficacy of imlunestrant, as monotherapy and in combination with targeted therapy, in ER-positive (ER+) advanced breast cancer (ABC) and endometrial endometrioid cancer. The ER+/human epidermal growth factor receptor 2-negative (HER2-) ABC experience is reported here.

METHODS

An i3+3 dose-escalation design was used, followed by dose expansions of imlunestrant as monotherapy or in combination with abemaciclib with or without aromatase inhibitor (AI), everolimus, or alpelisib. Imlunestrant was administered orally once daily and with the combination partner per label.

RESULTS

Overall, 262 patients with ER+/HER2- ABC were treated (phase Ia, n = 74; phase Ib, n = 188). Among patients who received imlunestrant monotherapy (n = 114), no dose-limiting toxicities or discontinuations occurred. At the RP2D (400 mg once daily), patients (n = 51) reported grade 1-2 nausea (39.2%), fatigue (39.2%), and diarrhea (29.4%). Patients at RP2D had received previous cyclin-dependent kinase 4/6 inhibitor (CDK4/6i; 92.2%), fulvestrant (41.2%), and chemotherapy (29.4%) for ABC and achieved a median progression-free survival (mPFS) of 7.2 months (95% CI, 3.7 to 8.3). Among patients who received imlunestrant + abemaciclib (n = 42) and imlunestrant + abemaciclib + AI (n = 43), most (69.4%) were treatment-naïve for ABC; all were CDK4/6i-naïve. Patients treated with imlunestrant + everolimus (n = 42)/alpelisib (n = 21) had received previous CDK4/6i (100%), fulvestrant (34.9%), and chemotherapy (17.5%) for ABC. No new safety signals or interactions with partnered drugs were observed. The mPFS was 19.2 months (95% CI, 13.8 to not available) for imlunestrant + abemaciclib and was not reached for imlunestrant + abemaciclib + AI. The mPFS with imlunestrant + everolimus/alpelisib was 15.9 months (95% CI, 11.3 to 19.1)/9.2 months (95% CI, 3.7 to 11.1). Antitumor activity was evident regardless of ESR1 mutation status.

CONCLUSION

Imlunestrant, as monotherapy or in combination with targeted therapy, had a manageable safety profile with evidence of preliminary antitumor activity in ER+/HER2- ABC.

Navigating Treatment Pathways in Metastatic Hormone Receptor-Positive, HER2-Negative Breast Cancer: Optimizing Second-Line Endocrine and Targeted Therapies

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.

Unveiling the Potential of Cyclin-Dependent Kinases 4 and 6 Inhibitors Beyond Progression in Hormone Receptor Positive/Human Epidermal Growth Factor Negative Advanced Breast Cancer - A Clinical Review

OPINION STATEMENT

Cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i) have revolutionized the management of hormone receptor-positive (HR +) breast cancer. However, resistance to CDK4/6i remains an unavoidable challenge, with limited evidence to guide the choice of subsequent treatments. Continuation of CDK4/6 inhibition raises as a compelling treatment option and is currently an active area of research. This approach encompasses multifaceted strategies regarding CDK4/6i sequence (same or switched agent), endocrine therapy (ET) partner and potential combination with a third drug. Continuing CDK4/6 inhibition while targeting ET resistance in tumours still dependent on ER activity (i.e., ESR1 mutation) through a ctDNA-guided approach has the potential of becoming practice-changing, pending the results of ongoing phase III studies. Conversely, the efficacy of this strategy in cases of radiological progression in a biomarker-unselected population appears to be rather unsatisfactory. While some benefit, albeit modest, has been observed from switching to a different CDK4/6i after progression (e.g. ribociclib after palbociclib in the MAINTAIN trial and abemaciclib after both palbociclib and ribociclib in the postMONARCH trial), the current evidence (mainly with palbociclib) clearly argues against maintaining the same CDK4/6i. Biomarker analyses to optimally identify patients suitable for this approach yielded inconsistent findings that do not apply to daily clinical decision making. Attractive preliminary efficacy has recently emerged from combining a third agent (immunotherapy, AKT/ PIK3CA/mTOR inhibitor, new ET agents, CDK2 inhibitors) to CDK4/6i and ET, but further validation in larger ongoing trials is required to also determine the optimal timing for incorporating these agents into the therapeutic timeline. To date, CDK4/6i after CDK4/6i progression is far from being a standard of care. However, selected patients with indolent disease, prolonged exposure to previous CDK4/6i treatment (especially palbociclib) and without actionable molecular alterations, may be suitable for suchmaintenance strategy beyond progression. In this challenging and rapidly evolving treatment landscape, ongoing studies can refine the optimal approach and identify clinical and molecular factors to select the best treatment for the right patient.

Practical treatment strategies and novel therapies in the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway in hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative (HR+/HER2-) advanced breast cancer

Mutations in the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway occur in 30%-40% of patients with advanced hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative (HR+/HER2-) breast cancer. For most patients, endocrine therapy with a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor is the first-line treatment. Recent studies indicate that adding inavolisib, a PI3Kα inhibitor, to palbociclib/fulvestrant benefits patients with endocrine-resistant HR+/HER2- metastatic breast cancer with a PIK3CA mutation. Alpelisib and capivasertib are both US Food and Drug Administration (FDA) approved in combination with fulvestrant in patients with endocrine-resistant HR+/HER2-, PIK3CA-mutant metastatic breast cancer, both with activity in the post-CDK4/6 setting. Capivasertib added to fulvestrant is the first AKT inhibitor to show a significant progression-free survival benefit with a trend for overall survival benefit and the only approved option for patients with phosphate and tensin homolog (PTEN) or AKT alterations. Toxicity profiles of all agents necessitate careful patient selection. Several mutant-selective and pan-mutant-selective novel inhibitors are under investigation with the potential to improve tolerability and efficacy.

Everolimus treatment in patients with hormone receptor-positive and human epidermal growth factor receptor 2-negative advanced breast cancer and a predictive model for its efficacy: a multicenter real-world study

Background

Everolimus is beneficial for patients with hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC). However, some patients developed drug resistance and the well-established predictor for everolimus efficacy was limited.

Objectives

The study was designed to evaluate the efficacy of everolimus in different treatment lines and identify several clinicopathological markers to estimate everolimus efficacy in patients with HR+/HER2- ABC.

Design

This was a retrospective and multicenter study.

Methods

Between 2014 and 2022, more than 2000 patients with tumors who received everolimus were collected from multiple cancer centers in China (National Cancer Center, Chinese PLA General Hospital, Peking University Cancer Hospital & Institute). A training cohort and two validation cohorts were developed.

Results

The training cohort included 338 patients. The median progression-free survival (PFS) for everolimus was 5.6 months, with an objective response rate of 25.1% and a clinical benefit rate of 54.4%. PFS was significantly worse from first-line (1L) to second-line (2L) to third-line (3L), with PFS1L for 13.5 months, PFS2L for 6.1 months, and PFS3L for 4.1 months (p = 2.9e-6, hazard ratio (HR) = 0.70, 95% confidence interval (CI) = 0.61-0.82). The clinicopathological characteristics, including post-1L everolimus treatment, Ki67 index of more than 40%, more than two metastatic sites at first recurrence, and receiving adjuvant chemotherapy, were independent risk factors for PFS. A predictive model for everolimus efficacy was established using these four factors. In the low-risk group, patients achieved a median PFS of 12.6 months, significantly longer compared to 2.7 months for those in the high-risk group (p = 2.4e-64, HR = 9.41, 95% CI = 7.05-12.56). The area under the curve was 0.96, 0.95, and 0.94 for 6-month, 1-year, and 3-year PFS, respectively. Internal validation cohort (PFS 18.4 vs 3.1 months, p = 3.6e-11, HR = 3.78, 95% CI = 2.49-5.74) and external validation cohort (PFS 13.5 vs 3.1 months, p = 2.9e-10, HR = 11.53, 95% CI = 4.68-28.37) confirmed its power for estimating clinical benefits of everolimus.

Conclusion

A predictive model was successfully established to predict survival outcomes for everolimus in patients with HR+/HER2- ABC, which may provide references for the management of everolimus in Chinese patients with HR+/HER2- ABC.

Mechanisms of endocrine resistance in hormone receptor-positive breast cancer

Hormone receptor-positive breast cancer may recur or metastasize years or decades after its diagnosis. Furthermore, hormone receptor expression may persist in relapsed or metastatic cancer cells. Endocrine therapy is one of the most efficacious treatments for hormone receptor-positive breast cancers. Nevertheless, a considerable proportion of patients develop resistance to endocrine therapy. Previous studies have identified numerous mechanisms underlying drug resistance, such as epigenetic abnormalities in the estrogen receptor (ER) genome, activation of ER-independent ligands, and alterations in signaling pathways including PI3K/AKT/mTOR, Notch, NF-κB, FGFR, and IRE1-XBP1. This article reviews the mechanisms of endocrine resistance in hormone receptor-positive advanced breast cancer, drawing from previous studies, and discusses the latest research advancements and prospects.

Precision therapeutics and emerging strategies for HR-positive metastatic breast cancer

Anti-oestrogen-based therapies, often combined with a CDK4/6 inhibitor, are the current standard-of-care first-line therapy for patients with advanced-stage hormone receptor-positive (HR+) breast cancer. Resistance to anti-oestrogen agents inevitably occurs, mediated by oestrogen receptor (ER)-dependent or ER-independent mechanisms that drive tumour progression. Emerging endocrine therapies include, but are not limited to, next-generation oral ER degraders and proteolysis targeting chimeras, which might be particularly effective in patients with ESR1-mutant breast cancer. Furthermore, cancers harbouring driver alterations in oncogenic signalling pathways, including AKT and PI3K, might be susceptible to novel combination strategies involving targeted inhibitors. Next-generation CDK2/4 inhibitors are an area of active clinical investigation, and efforts are ongoing to evaluate the role of sequential CDK inhibition. Approved and emerging antibody-drug conjugates exploiting novel target antigens have also demonstrated promising clinical activity. These novel agents, as well as further identification and characterization of predictive biomarkers, will hopefully continue to improve clinical outcomes, reduce the incidence of toxicities, and limit the extent of overtreatment in this population. In this Review, we describe the evolving treatment paradigm for patients with metastatic HR+ breast cancer in light of the growing armamentarium of drugs and biomarkers that will help to shape the future therapeutic landscape. These strategies are expected to involve tumour molecular profiling to enable the delivery of precision medicine.

Effectiveness of combined targeted and hormonal therapies for post-menopausal women with hormone receptor-positive and HER2-negative advanced breast cancer: A systematic review and meta-analysis of RCTs

OBJECTIVE

we aim to synthesize available evidence on the effectiveness of hormonal plus targeted therapies for post-menopausal women with hormone receptor-positive and HER2-negative advanced breast cancer.

DATA SOURCES AND METHODS

We searched the following databases: Medline, PubMed, Cochrane Library, CINAHL, Web of Science, Scopus, and African Journal. Only studies that investigated the effectiveness of hormonal therapy combined with targeted therapy for HR+/HER2- advanced breast cancer treatment were included. The outcomes were progression-free survival (PFS), overall survival (OS) and objective response rate (ORR). A random-effect meta-analysis model was employed. Statistical analysis was performed using Comprehensive Meta-analysis version 3.

RESULTS

24 studies were included in the meta-analysis with an overall sample size of 7635. Median PFS, OS and ORR were found to be significantly increased in the combination group compared to hormonal monotherapy [SMD = 6.072 (95% CI = 3.785-8.360), p < 0.001], [SMD = 1.614 (95% CI = 0.139-3.089), p = 0.032] and [OR = 1.584 (CI 1.134-2.213), p = 0.007] respectively. Subgroup analysis showed a significant difference in PFS and ORR between patients who received "hormonal therapy + CDK4/6 inhibitors" vs hormonal therapy only [SMD = 6.015 (CI 3.069-8.960), p < 0.001], (OR = 1.828 (CI 1.030-3.243), p = 0.039] respectively.

CONCLUSION

Compared with hormonal monotherapy, targeted plus hormonal therapy significantly improves PFS, OS and ORR in postmenopausal women with HR+/HER2- advanced breast cancer.

Enhanced drug delivery with nanocarriers: a comprehensive review of recent advances in breast cancer detection and treatment

Breast cancer (BC) remains a leading cause of morbidity and mortality among women worldwide, with triple-negative breast cancer (TNBC) posing significant treatment challenges due to its aggressive phenotype and resistance to conventional therapies. Recent advancements in nanocarrier technology offer promising solutions for enhancing drug delivery, improving bioavailability, and increasing drug accumulation at tumor sites through targeted approaches. This review delves into the latest innovations in BC detection and treatment, highlighting the role of nanocarriers like polymeric micelles, liposomes, and magnetic nanoparticles in overcoming the limitations of traditional therapies. Additionally, the manuscript discusses the integration of cutting-edge diagnostic tools, such as multiplex PCR-Nested Next-Generation Sequencing (mPCR-NGS) and blood-based biomarkers, which are revolutionizing early detection and molecular profiling of BC. The convergence of these technologies not only enhances therapeutic outcomes but also paves the way for personalized medicine in BC management. This comprehensive review underscores the potential of nanocarriers in transforming BC treatment and emphasizes the critical importance of early detection in improving patient 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.

The role of everolimus in metastatic breast cancer and possibilities of moving forward-a narrative review

Background and Objective

In hormone-receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer endocrine-based therapies are preferred over chemotherapy. One of the treatment options is the combination of everolimus with exemestane or other endocrine drug in later lines mainly based on progression-free survival (PFS) results of the phase 3 BOLERO-2 trial. Altogether, clinical trials did not prove an overall survival (OS) benefit and considerable side effects hampered its application in the day-by-day practice. In recent years CDK4/6-inhibitors became a first-choice combination partner to the endocrine treatment, everolimus still has a place within the treatment armamentarium. Although everolimus is a targeted drug, there is no accepted predictive biomarker and further patient selection is not possible. However, several directions can be defined how to optimally use everolimus. For update information on everolimus treatment in breast cancer I have performed a literature search.

Methods

I used the keywords "breast cancer" and "everolimus" and extended the search in PubMed from 01/01/2014 to 10/02/2023. I considered all phase 3 trials, the phase 1-2 trials with not repetitive information, studies with biomarker results and I also checked review articles to identify potential relevant other clinical trial reports. I also have made a search in clinicaltrials.gov for recently completed and ongoing trials.

Key Content and Findings

I summarized the search results in this concise and brief report focusing on main trial results and ongoing research with everolimus.

Conclusions

The most promising research directions seem to be further investigations for useable predictive biomarkers, for combinations with other targeted drugs (even in a triple combination) and for the feasibility of pharmacologically guided dosing method.

PI3K/AKT/mTOR signaling pathway: an important driver and therapeutic target in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly heterogeneous tumor lacking estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. It has higher aggressiveness and metastasis than other subtypes, with limited effective therapeutic strategies, leading to a poor prognosis. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling pathway is prevalently over-activated in human cancers and contributes to breast cancer (BC) growth, survival, proliferation, and angiogenesis, which could be an interesting therapeutic target. This review summarizes the PI3K/AKT/mTOR signaling pathway activation mechanism in TNBC and discusses the relationship between its activation and various TNBC subtypes. We also report the latest clinical studies on kinase inhibitors related to this pathway for treating TNBC. Our review discusses the issues that need to be addressed in the clinical application of these inhibitors.

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.

Navigating the Intricacies of Tumor Heterogeneity: An Insight into Potential Prognostic Breast Cancer Biomarkers

Breast cancer is a heterogeneous disease with diverse histological and molecular subtypes. Luminal breast tumors are the most diagnosed subtype. In luminal breast cancer, hormone receptors (including ER, PR, HER2) play a diagnostic and prognostic role. Despite the effectiveness of endocrine therapy in luminal breast tumors, tumor recurrence and resistance occur, and this may highlight evolutionary strategies for survival driven by stemness. In this review we thus consider the association between estrogen signaling and stemness in mediating tumor processes. Many studies report stemness as one of the factors promoting tumor progression. Its association with estrogen signaling warrants further investigation and provides an opportunity for the identification of novel biomarkers which may be used for diagnostic, prognostic, and therapeutic purposes. Breast cancer stem cells have been characterized (CD44+ CD24-) and their role in promoting treatment resistance and tumor recurrence widely studied; however, the complexity of tumor progression which also involve microenvironmental factors suggests the existence of more varied cell phenotypes which mediate stemness and its role in tumor progression.

Guidelines for diagnosis and treatment of advanced breast cancer in China (2022 edition)

Breast cancer is the most common cancer among women worldwide. It has been estimated that about 416 000 new cases and over 117 000 deaths of breast cancer occurred in China in 2020. Among the new cases of breast cancer diagnosed each year, 3-10% have distant metastasis at the time of initial diagnosis. In addition, approximately 30% of patients with early-stage breast cancer may eventually experience recurrence or metastases. The 5-year survival rate of patients with advanced breast cancer is only 20% with a median overall survival of 2-3 years. Although advanced breast cancer remains incurable at present, new therapeutic options and multidisciplinary treatment could be utilized to alleviate symptoms, improve quality of life, and prolong patients' survival. The choice of treatment regimens for patients with advanced breast cancer is very important, and the optimal treatment strategy beyond the first- and second-line therapy is often lacking. Herein, the China Advanced Breast Cancer Guideline Panel discussed and summarized recent clinical evidence, updated the guidelines for the diagnosis and treatment of advanced breast cancer based on the 2020 edition, and formulated the "Guidelines for diagnosis and treatment of advanced breast cancer in China (2022 edition)" for clinicians' reference.

Systemic Therapy in Breast Cancer

Therapeutic advances in breast cancer have significantly improved outcomes in recent decades. In the early setting, there has been a gradual shift from adjuvant-only to neoadjuvant strategies, with a growing focus on customizing post-neoadjuvant treatments through escalation and de-escalation based on pathologic response. At the same time, the transition from a pre-genomic to a post-genomic era, utilizing specific assays in the adjuvant setting and targeted sequencing in the advanced stage, has deepened our understanding of disease biology and aided in identifying molecular markers associated with treatment benefit. Finally, the introduction of new drug classes such as antibody-drug conjugates, and the incorporation in the (neo)adjuvant setting of therapies previously investigated in the advanced stage, like immunotherapy and CDK4-6 inhibitors, poses new challenges in treatment sequencing.

Reporting on patient's body mass index (BMI) in recent clinical trials for patients with breast cancer: a systematic review

BACKGROUND

The proportion of patients with breast cancer and obesity is increasing. While the therapeutic landscape of breast cancer has been expanding, we lack knowledge about the potential differential efficacy of most drugs according to the body mass index (BMI). Here, we conducted a systematic review on recent clinical drug trials to document the dosing regimen of recent drugs, the reporting of BMI and the possible exclusion of patients according to BMI, other adiposity measurements and/or diabetes (leading comorbidity of obesity). We further explored whether treatment efficacy was evaluated according to BMI.

METHODS

A search of Pubmed and ClinicalTrials.gov was performed to identify phase I-IV trials investigating novel systemic breast cancer treatments. Dosing regimens and exclusion based on BMI, adiposity measurements or diabetes, documentation of BMI and subgroup analyses according to BMI were assessed.

RESULTS

495 trials evaluating 26 different drugs were included. Most of the drugs (21/26, 81%) were given in a fixed dose independent of patient weight. BMI was an exclusion criterion in 3 out of 495 trials. Patients with diabetes, the leading comorbidity of obesity, were excluded in 67/495 trials (13.5%). Distribution of patients according to BMI was mentioned in 8% of the manuscripts, subgroup analysis was performed in 2 trials. No other measures of adiposity/body composition were mentioned in any of the trials. Retrospective analyses on the impact of BMI were performed in 6 trials.

CONCLUSIONS

Patient adiposity is hardly considered as most novel drug treatments are given in a fixed dose. BMI is generally not reported in recent trials and few secondary analyses are performed. Given the prevalence of patients with obesity and the impact obesity can have on pharmacokinetics and cancer biology, more attention should be given by investigators and study sponsors to reporting patient's BMI and evaluating its impact on treatment efficacy and toxicity.

Optimal targeting of PI3K-AKT and mTOR in advanced oestrogen receptor-positive breast cancer

The growing availability of targeted therapies for patients with advanced oestrogen receptor-positive breast cancer has improved survival, but there remains much to learn about the optimal management of these patients. The PI3K-AKT and mTOR pathways are among the most commonly activated pathways in breast cancer, whose crucial role in the pathogenesis of this tumour type has spurred major efforts to target this pathway at specific kinase hubs. Approvals for oestrogen receptor-positive advanced breast cancer include the PI3K inhibitor alpelisib for PIK3CA-mutated tumours, the AKT inhibitor capivasertib for tumours with alterations in PIK3CA, AKT1, or PTEN, and the mTOR inhibitor everolimus, which is used irrespective of mutation status. The availability of different inhibitors leaves physicians with a potentially challenging decision over which of these therapies should be used for individual patients and when. In this Review, we present a comprehensive summary of our current understanding of the pathways and the three inhibitors and discuss strategies for the optimal sequencing of therapies in the clinic, particularly after progression on a CDK4/6 inhibitor.

Fulvestrant and everolimus efficacy after CDK4/6 inhibitor: a prospective study with circulating tumor DNA analysis

In a prospective study (NCT02866149), we assessed the efficacy of fulvestrant and everolimus in CDK4/6i pre-treated mBC patients and circulating tumor DNA (ctDNA) changes throughout therapy. Patients treated with fulvestrant and everolimus had their ctDNA assessed at baseline, after 3-5 weeks and at disease progression. Somatic mutations were identified in archived tumor tissues by targeted NGS and tracked in cell-free DNA by droplet digital PCR. ctDNA detection was then associated with clinicopathological characteristics and patients' progression-free survival (PFS), overall survival (OS) and best overall response (BOR). In the 57 included patients, median PFS and OS were 6.8 (95%CI [5.03-11.5]) and 38.2 (95%CI [30.0-not reached]) months, respectively. In 47 response-evaluable patients, BOR was a partial response or stable disease in 15 (31.9%) and 11 (23.4%) patients, respectively. Among patients with trackable somatic mutation and available plasma sample, N = 33/47 (70.2%) and N = 19/36 (52.8%) had ctDNA detected at baseline and at 3 weeks, respectively. ctDNA detection at baseline and PIK3CA mutation had an adverse prognostic impact on PFS and OS in multivariate analysis. This prospective cohort study documents the efficacy of fulvestrant and everolimus in CDK4/6i-pretreated ER + /HER2- mBC and highlights the clinical validity of early ctDNA changes as pharmacodynamic biomarker.

Targeting autophagy drug discovery: Targets, indications and development trends

Autophagy plays a vital role in sustaining cellular homeostasis and its alterations have been implicated in the etiology of many diseases. Drugs development targeting autophagy began decades ago and hundreds of agents were developed, some of which are licensed for the clinical usage. However, no existing intervention specifically aimed at modulating autophagy is available. The obstacles that prevent drug developments come from the complexity of the actual impact of autophagy regulators in disease scenarios. With the development and application of new technologies, several promising categories of compounds for autophagy-based therapy have emerged in recent years. In this paper, the autophagy-targeted drugs based on their targets at various hierarchical sites of the autophagic signaling network, e.g., the upstream and downstream of the autophagosome and the autophagic components with enzyme activities are reviewed and analyzed respectively, with special attention paid to those at preclinical or clinical trials. The drugs tailored to specific autophagy alone and combination with drugs/adjuvant therapies widely used in clinical for various diseases treatments are also emphasized. The emerging drug design and development targeting selective autophagy receptors (SARs) and their related proteins, which would be expected to arrest or reverse the progression of disease in various cancers, inflammation, neurodegeneration, and metabolic disorders, are critically reviewed. And the challenges and perspective in clinically developing autophagy-targeted drugs and possible combinations with other medicine are considered in the review.

Prevalent landscape of tumor genomic alterations of luminal B1 breast cancers using a comprehensive genomic profiling assay in Taiwan

BACKGROUND

The human epidermal growth factor receptor 2 (HER2) negative luminal B1 subtype of breast cancer has been reported with a poorer outcome than luminal A in recent studies. This study aimed to investigate the molecular alterations and identify potential therapeutic targets by analyzing the genetic profiling from a cohort of luminal B1 breast cancer in Taiwan.

METHODS

We enrolled patients with luminal B1 breast cancer in our study. They were classified as patients who received curative surgery and adjuvant or neoadjuvant chemotherapy as the low-risk group, and who had advanced or metastatic disease or early relapse during the follow-up time as the high-risk group. Using targeted sequencing, we evaluated genomic alterations, interpreting variants with the ESMO Scale of clinical actionability of molecular targets (ESCAT).

RESULTS

A total of 305 luminal B1 breast cancer patients underwent targeted sequencing analyses. The high-risk patients reported more actionable genes and called variants than the low-risk group (P < 0.05). PIK3CA (42%), FGFR1 (25%), and BRCA1/2 (10.5%) were the most prevalent ESCAT actionable alterations in luminal B1 breast cancer. There was no difference in the prevalence of actionable mutations between these two groups, except for ERBB2 oncogenic mutations, which were more prevalent among the high-risk than the low-risk group (P < 0.05). Alterations in PTEN, ERBB2, and BRCA1/2 were associated with disease relapse events in luminal B1 breast cancer.

CONCLUSIONS

PIK3CA, FGFR1, and BRCA1/2 were the most prevalent actionable alterations among Taiwanese luminal B1 breast cancer. Moreover, PTEN and BRCA1/2 was significantly associated with disease relapse.

Current and emerging treatment approaches for hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer

In the past decade, significant progress was made in treating hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC), but many clinical questions remain. Cyclin-dependent kinase 4/6 inhibitors are now widely used in combination with endocrine therapy (ET) as standard of care, having demonstrated significant progression-free survival versus ET, and also significant overall survival benefits in the metastatic setting. Inhibition of the PI3K/AKT/mTOR intracellular signaling pathway coupled with ET typically follows first-line therapies. Novel endocrine options including oral selective estrogen receptor down-regulators (SERDs) are in late phases of development, with elacestrant being the first oral SERD to be approved for ESR1-mutant mBC. However, endocrine-refractory disease is inevitable in most patients and represents an area of unmet need, with current recommended options offering poor efficacy, undesirable toxicity, and reduced quality of life. Breakthrough advances in the metastatic setting came via the development of antibody-drug conjugates, which have the advantage of delivering cytotoxic payloads to tumor cells with higher tumor selectivity. Trastuzumab deruxtecan offers a novel therapeutic option for patients with HR+/HER2-low mBC and sacituzumab govitecan is a novel therapeutic option for patients with HR+/HER2- mBC, including those with unmet treatment need in the later-line endocrine-refractory setting. Data gaps still exist regarding optimal sequencing of these novel agents; additional studies into mechanisms of resistance in the metastatic setting would provide further insights. Herein, we describe the current treatment options for HR+/HER2- mBC, including the latest practice-impacting data, and provide commentary on future directions.

A second-generation eIF4A RNA helicase inhibitor exploits translational reprogramming as a vulnerability in triple-negative breast cancer

In this study, we aimed to address the current limitations of therapies for macro-metastatic triple-negative breast cancer (TNBC) and provide a therapeutic lead that overcomes the high degree of heterogeneity associated with this disease. Specifically, we focused on well-documented but clinically underexploited cancer-fueling perturbations in mRNA translation as a potential therapeutic vulnerability. We therefore developed an orally bioavailable rocaglate-based molecule, MG-002, which hinders ribosome recruitment and scanning via unscheduled and non-productive RNA clamping by the eukaryotic translation initiation factor (eIF) 4A RNA helicase. We demonstrate that MG-002 potently inhibits mRNA translation and primary TNBC tumor growth without causing overt toxicity in mice. Importantly, given that metastatic spread is a major cause of mortality in TNBC, we show that MG-002 attenuates metastasis in pre-clinical models. We report on MG-002, a rocaglate that shows superior properties relative to existing eIF4A inhibitors in pre-clinical models. Our study also paves the way for future clinical trials exploring the potential of MG-002 in TNBC and other oncological indications.

A network meta-analysis of efficacy and safety for first-line and second/further-line therapies in postmenopausal women with hormone receptor-positive, HER2-negative, advanced breast cancer

BACKGROUND

Hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR + /HER2 -) advanced breast cancer is a prevalent subtype among postmenopausal women. Despite the growing number of randomized clinical trials (RCTs) exploring this topic, the efficacy and safety of first-line and second/further-line treatments remain uncertain. Accordingly, our aim was to conduct a comprehensive evaluation of the efficacy and safety of these therapies through network meta-analysis.

METHODS

RCTs were identified by searching Pubmed, Embase, and major cancer conferences. The efficacy of interventions was assessed using the hazard ratios (HRs) of progression-free survival (PFS) and overall survival (OS), while safety was indicated by the incidence of any grade adverse events (AEs), grade 3-5 AEs, AEs leading to treatment discontinuation, and AEs leading to death. Both time-variant HRs fractional polynomial models and time-invariant HRs Cox-proportional hazards models were considered for handling time-to-event data. Safety indicators were analyzed using Bayesian network meta-analysis. Additionally, subgroup analyses were conducted based on patient characteristics.

RESULTS

A total of 41 RCTs (first-line 17, second/further-lines 27) were included in the analysis. For first-line treatment, the addition of Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors to endocrine therapy significantly improved therapeutic efficacy in terms of both PFS and OS, demonstrating the best performance across all mechanisms. Specifically, the combination of Abemaciclib and Letrozole demonstrated the most favorable performance in terms of PFS, while Ribociclib plus Fulvestrant yielded the best outcomes in OS. Incorporating the immune checkpoint inhibitor Avelumab into the regimen with CDK4/6 inhibitors and selective estrogen receptor degraders significantly enhanced both PFS and OS in second-line or later treatments. Regarding safety, endocrine monotherapy performed well. Regarding safety, endocrine monotherapy performed well. There is mounting evidence suggesting that most CDK4/6 inhibitors may demonstrate poorer performance with respect to hematologic AEs. However, additional evidence is required to further substantiate these findings.

CONCLUSIONS

CDK4/6 inhibitors, combined with endocrine therapy, are pivotal in first-line treatment due to their superior efficacy and manageable AEs. For second/further-line treatment, adding immune checkpoint inhibitors to CDK4/6 inhibitors plus endocrine therapy may produce promising results. However, to reduce the results' uncertainty, further trials comparing these novel treatments are warranted.

TRIAL REGISTRATION

Registration number: PROSPERO (CRD42022377431).

Peroxisome proliferator-activated receptorα/γ agonist pioglitazone for rescuing relapsed or refractory neoplasias by unlocking phenotypic plasticity

A series of seven clinical trials on relapsed or refractory (r/r) metastatic neoplasias followed the question: Are networks of ligand-receptor cross-talks that support tumor-specific cancer hallmarks, druggable with tumor tissue editing approaches therapeutically exploiting tumor plasticity? Differential recombinations of pioglitazone, a dual peroxisome-proliferator activated receptorα/γ (PPARα/γ) agonist, with transcriptional modulators, i.e., all-trans retinoic acid, interferon-α, or dexamethasone plus metronomic low-dose chemotherapy (MCT) or epigenetic modeling with azacitidine plus/minus cyclooxygenase-2 inhibition initiated tumor-specific reprogramming of cancer hallmarks, as exemplified by inflammation control in r/r melanoma, renal clear cell carcinoma (RCCC), Hodgkin's lymphoma (HL) and multisystem Langerhans cell histiocytosis (mLCH) or differentiation induction in non-promyelocytic acute myeloid leukemia (non-PML AML). Pioglitazone, integrated in differentially designed editing schedules, facilitated induction of tumor cell death as indicated by complete remission (CR) in r/r non-PML AML, continuous CR in r/r RCCC, mLCH, and in HL by addition of everolimus, or long-term disease control in melanoma by efficaciously controlling metastasis, post-therapy cancer repopulation and acquired cell-resistance and genetic/molecular-genetic tumor cell heterogeneity (M-CRAC). PPARα/γ agonists provided tumor-type agnostic biomodulatory efficacy across different histologic neoplasias. Tissue editing techniques disclose that wide-ranging functions of PPARα/γ agonists may be on-topic focused for differentially unlocking tumor phenotypes. Low-dose MCT facilitates targeted reprogramming of cancer hallmarks with transcriptional modulators, induction of tumor cell death, M-CRAC control and editing of non-oncogene addiction. Thus, pioglitazone, integrated in tumor tissue editing protocols, is an important biomodulatory drug for addressing urgent therapeutic problems, such as M-CRAC in relapsed or refractory tumor disease.

Case report: ex vivo tumor organoid drug testing identifies therapeutic options for stage IV ovarian carcinoma

Patients presenting with stage 4 ovarian carcinoma, including low-grade serous disease, have a poor prognosis. Although platinum-based therapies can offer some response, these therapies are associated with many side effects, and treatment resistance often develops. Toxic side effects along with disease progression render patients unable to receive additional lines of treatment and limit their options to hospice or palliative care. In this case report, we describe a patient with an unusual case of metastatic low-grade serous ovarian cancer with some features of high-grade disease who had received four previous lines of treatment and was suffering from atelectasis, pulmonary embolism, and hydronephrosis. A CLIA-certified drug sensitivity assay of an organoid culture derived from the patient's tumor (PARIS® test) identified several therapeutic options, including the combination of fulvestrant with everolimus. On this treatment regimen, the patient experienced 7 months of stable disease and survived nearly 11 months before succumbing to her disease. This case emphasizes the clinical utility of ex vivo drug testing as a new functional precision medicine approach to identify, in real-time, personalized treatment options for patients, especially those who are not benefiting from standard of care treatments.

Unfolding the role of the PI3K/AKT/MTOR pathway in male breast cancer: A pragmatic appraisal

Breast cancer in men is rare, but a relevant public health issue, yielding a 25% higher risk of mortality comparing to female counterparts. The representation of males in clinical trials has been scarce and treatment decisions are based mainly on extrapolations from data in females. In the setting of estrogen-dependent metastatic disease, the use of everolimus has been seldom reported, although the PI3K/AKT/mTOR pathway seems to be a critical oncogenic driver. This paper dissects hallmark biological features of ER+/HER2-advanced male breast cancer, setting a comprehensive basis to promote personalized care, focusing on the potential of targeting the PI3K/AKT/mTOR pathway.

Exploring the role of PI3K/AKT/mTOR inhibitors in hormone-related cancers: A focus on breast and prostate cancer

Breast cancer (BC) and prostate cancer (PC) are at the top of the list when it comes to the most common types of cancers worldwide. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway is important, in that it strongly influences the development and progression of these tumors. Previous studies have emphasized the key role of inhibitors of the PIK3/AKT/mTOR signaling pathway in the treatment of BC and PC, and it remains to be a crucial method of treatment. In this review, the inhibitors of these signaling pathways are compared, as well as their effectiveness in therapy and potential as therapeutic agents. The use of these inhibitors as polytherapy is evaluated, especially with the use of hormonal therapy, which has shown promising results.

Systemic therapy for hormone receptor-positive/human epidermal growth factor receptor 2-negative early stage and metastatic breast cancer

Hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer is defined by the presence of the estrogen receptor and/or the progesterone receptor and the absence of HER2 gene amplification. HR-positive/HER2-negative breast cancer accounts for 65%-70% of all breast cancers, and incidence increases with increasing age. Treatment varies by stage, and endocrine therapy is the mainstay of treatment in both early stage and late-stage disease. Combinations with cyclin-dependent kinase 4/6 inhibitors have reduced distant recurrence in the early stage setting and improved overall survival in the metastatic setting. Chemotherapy is used based on stage and tumor biology in the early stage setting and after endocrine resistance for advanced disease. New therapies, including novel endocrine agents and antibody-drug conjugates, are now changing the treatment landscape. With the availability of new treatment options, it is important to define the optimal sequence of treatment to maximize clinical benefit while minimizing toxicity. In this review, the authors first discuss the pathologic and molecular features of HR-positive/HER2-negative breast cancer and mechanisms of endocrine resistance. Then, they discuss current and emerging therapies for both early stage and metastatic HR-positive/HER2-negative breast cancer, including treatment algorithms based on current data.

CDK4/6 inhibitors, PI3K/mTOR inhibitors, and HDAC inhibitors as second-line treatments for hormone receptor-positive, HER2-negative advanced breast cancer: a network meta-analysis

BACKGROUND

This study sought to compare the benefits and safety of agents including Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) inhibitors, and histone deacetylase (HDAC) inhibitors as second-line treatments for these patients by conducting a comprehensive systematic review and network meta-analysis.

METHODS

The Medline, Embase and Cochrane Library databases were searched for randomized trials comparing CDK4/6 inhibitors, PI3K/mTOR inhibitors, or HDAC inhibitors vs. placebo with the addition of exemestane or fulvestrant as second-line treatments in patients with HR + advanced breast cancer up to December 16, 2021. Outcomes of interest were progression-free survival (PFS), overall response rate (ORR), overall survival (OS), clinical benefit rate (CBR), and grade 3-4 adverse drug events (ADEs). The present study was conducted according to the Cochrane Collaboration and PRISMA statements. The overall effect was pooled using the random effects model.

RESULTS

Seventeen studies with a total of 9,100 participants were included in the current study. Compared with placebo plus fulvestrant, PFS was significantly improved by CDK4/6 inhibitor plus fulvestrant, mTOR inhibitor plus fulvestrant, mTOR inhibitor plus exemestane, and PI3K inhibitor plus fulvestrant, but not HDAC inhibitor plus exemestane. While mTOR inhibitor plus exemestane was the best regimen (SUCRA value 89.5%), the mTOR inhibitor plus exemestane regimen induced more severe adverse events (SAEs) than the HDAC inhibitor plus exemestane regimen [OR, 95% CI: 2.40 (1.40-4.10)].

CONCLUSION

mTOR inhibitor and CDK4/6 inhibitor-based regimens demonstrated superior clinical efficacy and comparable safety profiles as second-line treatment in patients with HR-positive, HER2-negative advanced breast cancer.

The Role of Obesity in Breast Cancer Pathogenesis

Research has shown that obesity increases the risk for type 2 diabetes mellitus (Type 2 DM) by promoting insulin resistance, increases serum estrogen levels by the upregulation of aromatase, and promotes the release of reactive oxygen species (ROS) by macrophages. Increased circulating glucose has been shown to activate mammalian target of rapamycin (mTOR), a significant signaling pathway in breast cancer pathogenesis. Estrogen plays an instrumental role in estrogen-receptor-positive breast cancers. The role of ROS in breast cancer warrants continued investigation, in relation to both pathogenesis and treatment of breast cancer. We aim to review the role of obesity in breast cancer pathogenesis and novel therapies mediating obesity-associated breast cancer development. We explore the association between body mass index (BMI) and breast cancer incidence and the mechanisms by which oxidative stress modulates breast cancer pathogenesis. We discuss the role of glutathione, a ubiquitous antioxidant, in breast cancer therapy. Lastly, we review breast cancer therapies targeting mTOR signaling, leptin signaling, blood sugar reduction, and novel immunotherapy targets.

Is Palbociclib a cost-effective strategy in the second-line treatment of metastatic breast cancer in Iran?

BACKGROUND & AIMS

This study evaluates the cost-effectiveness of Palbociclib in the second-line treatment of hormone receptor-positive (HR+) human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC) in Iran.

METHODS

The present economic evaluation used a partitioned survival model (PSM). This model compares lifetime costs and disease outcomes among groups receiving different medication combinations containing Palbociclib, Fulvestrant, Everolimus, Ribociclib, and Abemaciclib as the second-line therapy for HR+/HER2- MBC. The model was conducted from Iran's healthcare perspective, structured with 1-month cycles, and the evaluation time horizon in the base analysis was set to 180 cycles (15 years). Transition probabilities were extracted using the survival curves. The cost information was extracted based on the year 2020. The Quality Adjusted Life Years (QALY) was considered the final outcome unit, and the cost-effectiveness of different combinations is calculated as cost per QALY. The annual discount rate of 5% was considered for costs and QALYs. Two times Iran's GDP per capita (800,000,000 IRR = US$5934) was used as the threshold. Finally, due to the uncertainty of some parameters, deterministic and probabilistic sensitivity analyses were carried out.

RESULTS

The base case results showed that the highest cost was for the 'Ribociclib+ Fulvestrant' combination (US$89,629.56), and the lowest price was for the 'Iranian Everolimus + Fulvestrant' combination (US$10,740.09). 'Palbociclib + Fulvestrant' brings about the highest value of 1.456 incremental QALYs compared to other strategies. Finally, the 'Iranian Palbociclib + Fulvestrant' was the cost-effective combination, with an incremental cost-effectiveness ratio (ICER) of US$4,201 compared to other strategies. The base case results were supported by the probabilistic sensitivity analysis. Deterministic sensitivity analysis showed that the cost of Iranian Palbociclib has a threshold of US$582.99.

CONCLUSIONS

The 'Iranian Palbociclib + Fulvestrant' combination was cost-effective in second-line therapy for HR+ HER2- MBC in Iran.

Addition of PI3K/AKT/mTOR inhibitors to fulvestrant for advanced HR+/HER2- breast cancer: a systematic review and meta-analysis

Purpose: To analyze whether adding PI3K/AKT/mTOR inhibitors to fulvestrant could restore endocrine therapy sensitivity for the treatment of postmenopausal patients with HR+, HER2- breast cancer. Methods: This meta-analysis was performed using RevMan 5.4 analysis software. Results: Nine studies that included a total of 3199 patients were analyzed. Compared with fulvestrant alone, the addition of PI3K/AKT/mTOR inhibitors significantly prolonged progression-free survival, overall survival and objective response rate of patients in both the total and PI3K-pathway-activated population. The number of grade 3-5 adverse events was also significantly higher. Conclusion: The addition of PI3K/AKT/mTOR to fulvestrant resulted in potential benefits; however, there may be a higher risk, which needs to be carefully managed.

Evaluating everolimus for the treatment of breast cancer

INTRODUCTION

Everolimus is an oral drug that inhibits mTOR with immunosuppressive and antiproliferative characteristics. It is commonly used in association with exemestane in hormone receptor (HR)-positive advanced breast cancer (ABC).

AREAS COVERED

The current review summarizes the publications relating to everolimus from clinical research in breast cancer. Everolimus showed treatment efficacy and an acceptable safety tolerance with prevention of side effects in Phase II/III studies. BOLERO-2 study showed a progression-free survival improvement in patients with HR-positive ABC previously treated with aromatase inhibitors (AI) and leading to its acceptance in this indication. The absence of a post CDK4/6 inhibitor (CDK4/6i.) study and the arrival of new drugs may raise questions about its current place in the therapeutic strategy.

EXPERT OPINION

Everolimus is relevant in the management of HR-positive ABC. Because of its efficacy, acceptable tolerability and the absence of drugs that have shown a greater benefit, it remains a second-line treatment option in HR-positive, HER2 negative (score 0) patients without BRCA mutation or visceral crisis and can be discuss with fulvestrant in second line after CDK4-6i. It is likely that within 5 years this treatment will be replaced in second line HR-positive breast cancer by new emerging treatments: drug-conjugated antibodies, tyrosine kinase inhibitors or immunotherapy in combination with chemotherapy.

The role of TSC2 in breast cancer: a literature review

TSC2 is a tumor suppressor gene as well as a disease-causing gene for autosomal dominant disorder tuberous sclerosis complex (TSC). Research has found that some tumor tissues have lower TSC2 expression levels than normal tissues. Furthermore, low expression of TSC2 is associated with poor prognosis in breast cancer. TSC2 acts as a convergence point of a complex network of signaling pathways and receives signals from the PI3K, AMPK, MAPK, and WNT pathways. It also regulates cellular metabolism and autophagy through inhibition of a mechanistic target of rapamycin complex, which are processes relevant to the progression, treatment, and prognosis of breast cancer. In-depth study of TSC2 functions provides significant guidance for clinical applications in breast cancer, including improving the treatment efficacy, overcoming drug resistance, and predicting prognosis. In this review, protein structure and biological functions of TSC2 were described and recent advances in TSC2 research in different molecular subtypes of breast cancer were summarized.

An emerging generation of endocrine therapies in breast cancer: a clinical perspective

Anti-estrogen therapy is a key component of the treatment of both early and advanced-stage hormone receptor (HR)-positive breast cancer. This review discusses the recent emergence of several anti-estrogen therapies, some of which were designed to overcome common mechanisms of endocrine resistance. The new generation of drugs includes selective estrogen receptor modulators (SERMs), orally administered selective estrogen receptor degraders (SERDs), as well as more unique agents such as complete estrogen receptor antagonists (CERANs), proteolysis targeting chimeric (PROTACs), and selective estrogen receptor covalent antagonists (SERCAs). These drugs are at various stages of development and are being evaluated in both early and metastatic settings. We discuss the efficacy, toxicity profile, and completed and ongoing clinical trials for each drug and highlight key differences in their activity and study population that have ultimately influenced their advancement.

How I treat endocrine-dependent metastatic breast cancer

Estrogen receptor-positive (ER+)/HER2-negative (HER2-), the so-called luminal-type breast cancer, is the most frequent subset, accounting for around 70% of all breast cancer cases. Endocrine therapy (ET) combined with cyclin-dependent kinases (CDK) 4/6 inhibitors is the standard first option in the management of advanced luminal breast cancer independently of disease extension. Classically, patients undergo multiple lines of ET ± targeted treatments until endocrine resistance occurs and palliative chemotherapy is proposed. Understanding endocrine resistance mechanisms and development of novel ET options is one of the main challenges in current clinical research. Another area of utmost interest is the improvement of post-endocrine therapeutic approaches. Among others, the development of antibody-drug conjugates (ADCs) is very promising, and some of these drugs will probably soon become a part of the therapeutic arsenal against this incurable disease. This review paper provides an overview of currently available treatment options in ER+/HER2- metastatic breast cancer and extensively discusses new approaches in late clinical development.

Filling the Gap after CDK4/6 Inhibitors: Novel Endocrine and Biologic Treatment Options for Metastatic Hormone Receptor Positive Breast Cancer

The rise of cyclin-dependent kinase (CDK)4/6 inhibitors has rapidly reshaped treatment algorithms for hormone receptor (HR)-positive metastatic breast cancer, with endocrine treatment (ET) plus a CDK4/6-inhibitor currently representing the standard of care in the first line setting. However, treatment selection for those patients experiencing progression while on ET + CDK4/6-inhibitors remains challenging due to the suboptimal activity or significant toxicities of the currently available options. There is also a paucity of data regarding the efficacy of older regimens, such as everolimus + exemestane, post-CDK4/6 inhibition. In this setting of high unmet need, several clinical trials of novel drugs have recently reported encouraging results: the addition of the AKT-inhibitor capivasertib to fulvestrant demonstrated a significant improvement in progression-free survival (PFS); the oral selective estrogen receptor degrader (SERD) elacestrant prolonged PFS compared to traditional ET in a phase 3 trial, particularly among patients with detectable ESR1 mutations; finally, PARP inhibitors are available treatment options for patients with pathogenic BRCA1/2 germline mutations. Overall, a plethora of novel endocrine and biologic treatment options are finally filling the gap between first-line ET and later line chemotherapy. In this review article, we recapitulate the activity of these novel treatment options and their potential role in future treatment algorithms.

Drugging the PI3K/AKT/mTOR Pathway in ER+ Breast Cancer

The frequent activation of the PI3K/AKT/mTOR pathway and its crucial role in estrogen receptor-positive (ER+) breast cancer tumorigenesis and drug resistance has made it a highly attractive therapeutic target in this breast cancer subtype. Consequently, the number of new inhibitors in clinical development targeting this pathway has drastically increased. Among these, the PIK3CA isoform-specific inhibitor alpelisib and the pan-AKT inhibitor capivasertib were recently approved in combination with the estrogen receptor degrader fulvestrant for the treatment of ER+ advanced breast cancer after progression on an aromatase inhibitor. Nevertheless, the clinical development of multiple inhibitors of the PI3K/AKT/mTOR pathway, in parallel with the incorporation of CDK4/6 inhibitors into the standard of care treatment in ER+ advanced breast cancer, has led to a multitude of available therapeutic agents and many possible combined strategies which complicate personalizing treatment. Here, we review the role of the PI3K/AKT/mTOR pathway in ER+ advanced breast cancer, highlighting the genomic contexts in which the various inhibitors of this pathway may have superior activity. We also discuss selected trials with agents targeting the PI3K/AKT/mTOR and related pathways as well as the rationale supporting the clinical development of triple combination therapy targeting ER, CDK4/6 and PI3K/AKT/mTOR in ER+ advanced breast cancer.

[Therapeutic strategies for the treatment of endocrine resistant hormone receptor positive advanced breast cancer]

HR+ breast cancers are defined by the prominence of signaling pathways dependent on the estrogen receptor. Endocrine therapy is the standard treatment for these advanced diseases. Resistance to these treatments, called hormone resistance, appears invariably with biological mechanisms that have led to the development of therapeutic opportunities. An exhaustive literature review was carried out concerning the biology of the hormone resistance pathways, the therapeutic options before the era of CDK4/6 inhibitors, the rise of CDK4/6 inhibitors and the therapeutic prospects in a situation of hormone resistance. Various biological abnormalities have been identified in the mechanisms of hormone resistance such as changes in the estrogen receptor, mutations in the ESR1 gene, aberrant activation of the PI3K pathway or cell cycle deregulations. Historical strategies for circumventing this hormone resistance have been based on hormonal manipulation, on the development of new endocrine therapy such as fulvestrant (selective estrogen receptor inhibitor, SERD), on combinations of treatments such as everolimus, a mTOR inhibitor. This strategy combining endocrine therapy and targeted therapy has led to the development of combinations with CDK4/6 inhibitors which have now become a standard treatment in the hormone resistance phase. The future of this therapeutic era remains to be written with new combinations of hormone therapy and targeted therapy such as PI3K inhibitors or even with the positioning of new SERDs in clinical development.

Endocrine Therapy-Based Strategies for Metastatic Breast Cancer with Different Endocrine Sensitivity Statuses: A Systematic Review and Network Meta-Analysis

BACKGROUND

Novel endocrine therapies (ETs) and targeted therapeutic regimens have been developed to dramatically improve the outcome of hormone receptor-positive (HR+)/HER2-negative (HER2-) metastatic breast cancer (mBC).

METHODS

We performed a systematic search with a predefined search strategy in PubMed, Embase and Cochrane CENTRAL databases to perform a network meta-analysis and evaluate the relative efficacies of ET-based treatment regimens in HR+/HER2- mBC patients with different endocrine sensitivity statuses. The study was registered in the PROSPERO database (CRD42021235570).

RESULTS

A total of 47 trials (20,267 patients) were included. Analysis of progression-free survival (PFS) in endocrine therapy-sensitive (ETS) patients revealed cyclin-dependent kinases 4/6 inhibitors (CDK4/6i) + fulvestrant 500 mg (Ful 500) (random effect (RE): hazard ratio (HR), 0.46; 95% credibility interval (CrI), 0.27-0.78; surface under the cumulative ranking curve (SUCRA), 0.93; fixed effect (FE): HR, 0.48; 95% CrI, 0.40-0.58; SUCRA, 0.99) to be the best therapy followed by CDK4/6i + aromatase inhibitors (AIs) (RE: HR, 0.53; 95% CrI, 0.40-0.72; SUCRA, 0.86; FE: HR, 0.54; 95% CrI, 0.48-0.61; SUCRA, 0.91). Chemotherapy followed by CDK4/6i + Ful 500 appears to be the most effective option for the endocrine therapy-resistant (ETR) group. Analysis of overall survival revealed CDK4/6i + Ful 500 (SUCRA: 0.99) and AKTi + Ful 500 (SUCRA: 0.87) to be the first-rank regimen for the ETS group and ETR groups, respectively.

CONCLUSION

Our comprehensive analysis suggests that CDK4/6i combined with ETs may be the best treatment option in terms of PFS for ETS patients and chemotherapy for ETR patients with HR+/HER2- mBC. Different endocrine sensitivity statuses required various optimal treatment strategies, which may provide guidance for clinical practice.

Anti-Hormonal Therapy in Breast Cancer and Its Effect on the Blood-Brain Barrier

The molecular receptor status of breast cancer has implications for prognosis and long-term metastasis. Although metastatic luminal B-like, hormone-receptor-positive, HER2−negative, breast cancer causes brain metastases less frequently than other subtypes, though tumor metastases in the brain are increasingly being detected of this patient group. Despite the many years of tried and tested use of a wide variety of anti-hormonal therapeutic agents, there is insufficient data on their intracerebral effectiveness and their ability to cross the blood-brain barrier. In this review, we therefore summarize the current state of knowledge on anti-hormonal therapy and its intracerebral impact and effects on the blood-brain barrier in breast cancer.