Systemic Therapy for Estrogen Receptor-Positive, HER2-Negative Breast Cancer

Quantitative evaluation of the efficacy and safety profiles of two types of targeted inhibitors combined with endocrine therapy in ER+/HER2- metastatic breast cancer

PURPOSE

The aim of this study was to quantitatively compare the efficacy and safety of CDK4/6 inhibitors and PI3K/AKT/mTOR inhibitors for ER+/HER2- metastatic breast cancer.

METHODS

A parametric survival function was used to analyze the time course of overall survival (OS) and progression-free survival (PFS). The objective response rate (ORR) and the incidence of any grade and grade 3-4 adverse events were summarized using the random-effects model of a single-arm meta-analysis.

RESULTS

This study included 44 arms from 48 publications, with a total sample size of 7881 patients. Our study revealed that CDK4/6 inhibitors had a median OS of 40.7 months, a median PFS of 14.8 months, and an ORR of 40%, whereas PI3K/AKT/mTOR inhibitors had a median OS of 29.8 months, a median PFS of 8.3 months, and an ORR of 20%. Additionally, this study also found that the proportion of patients with visceral metastases and specific endocrine therapy used in combination significantly impact OS and PFS. In terms of adverse events, CDK4/6 inhibitors exhibited a relatively high incidence of hematological adverse events.

CONCLUSION

Our study provides solid quantitative evidence for the first-line recommendation of CDK4/6 inhibitors combined with endocrine therapy for ER+/HER2- metastatic breast cancer in clinical guidelines.

Fulfilling the Role of a Parent While Undergoing Treatment for Cancer: A Review of the Literature and the Potential Impact of Childcare Support on Cancer Outcomes

Breast cancer is the most prevalent malignancy among adolescents and young adults (AYAs). Despite the efficacy of chemotherapy, AYA patients contend with psychosocial challenges, including psychological distress and financial toxicity, exacerbated further by those with dependent children. Parenting responsibilities intersect with cancer care, impacting both family dynamics and treatment adherence. Despite recognized needs, however, the impact of parenting concerns or even parenting status and the presence of dependents has not been systematically addressed and there is a paucity of interventional research regarding patients with cancer as concomitant caregivers. A feasibility study conducted by the Brown University Oncology Cooperative Group demonstrated the potential benefits of providing financial assistance for childcare, both improving treatment adherence and reducing distress among participants. Similar interventions have shown promise in addressing financial hardships for AYA patients with cancer who are concomitant caregivers. Ultimately, parenting concerns have a significant impact on medical decision-making, and further interventional research on childcare support is required to examine the ways in which health systems can improve family stability, stress, and quality of life.

PTX-RPPR, a conjugate of paclitaxel and NRP-1 peptide inhibitor to prevent tumor growth and metastasis

Paclitaxel, a potent anti-tumor drug widely recognized for its therapeutic efficacy, has faced limitations in clinical application due to its poor solubility. The use of Cremophor EL (CrEL) as a cosolvent in paclitaxel injections has been associated with hypersensitivity reactions in some patients. To overcome these challenges, we have developed a novel conjugate by linking a neuropilin-1 targeting peptide, RPPR, to paclitaxel, resulting in PTX-RPPR. This innovative approach has significantly enhanced the solubility of paclitaxel, achieving a 3.8 mg/mL concentration, a remarkable 90-fold increase over the native drug. PTX-RPPR has shown potent anti-tumor activity, inhibiting tumor cell proliferation with an IC50 ranging from 0.26 to 1.64 μM and effectively suppressing migration, invasion, and angiogenesis at a concentration of 75 nM. Notably, in a 4T1 mammary carcinoma model, PTX-RPPR administered at a dose of 0.7 μmol/kg exhibited tumor growth inhibition comparable to that of paclitaxel at a higher dose of 3.5 μmol/kg, with superior efficacy in preventing lung metastasis. Furthermore, PTX-RPPR effectively reduced NRP-1 expression in both tumors and lungs post-treatment. In contrast to paclitaxel formulated with CrEL, PTX-RPPR did not induce IL-6 expression, suggesting a safer profile in terms of immunological response. Characterized by a particle size of 200 nm and a zeta potential of +30 mV, the nano-formulation of PTX-RPPR demonstrated remarkable stability over seven days. This study introduced PTX-RPPR as a promising peptide-drug conjugate that addresses the solubility and hypersensitivity issues associated with paclitaxel, offering a safer therapeutic strategy for cancer treatment.

Clinical efficacy of tumor organoid-guided cancer therapy for locally advanced unresectable or metastatic breast cancer

Patient-derived organoids (PDOs) may facilitate treatment selection. This retrospective cohort study evaluated the feasibility and clinical benefit of using PDOs to guide personalized treatment in metastatic breast cancer (MBC). Patients diagnosed with MBC were recruited between January 2019 and August 2022. PDOs were established and the efficacy of customized drug panels was determined by measuring cell mortality after drug exposure. Patients receiving organoid-guided treatment (OGT) were matched 1:2 by nearest neighbor propensity scores with patients receiving treatment of physician's choice (TPC). The primary outcome was progression-free survival. Secondary outcomes included objective response rate and disease control rate. Targeted gene sequencing and pathway enrichment analysis were performed. Forty-six PDOs (46 of 51, 90.2%) were generated from 45 MBC patients. PDO drug screening showed an accuracy of 78.4% (95% CI 64.9%-91.9%) in predicting clinical responses. Thirty-six OGT patients were matched to 69 TPC patients. OGT was associated with prolonged median progression-free survival (11.0 months vs. 5.0 months; hazard ratio 0.53 [95% CI 0.33-0.85]; p = .01) and improved disease control (88.9% vs. 63.8%; odd ratio 4.26 [1.44-18.62]) compared with TPC. The objective response rate of both groups was similar. Pathway enrichment analysis in hormone receptor-positive, human epidermal growth factor receptor 2-negative patients demonstrated differentially modulated pathways implicated in DNA repair and transcriptional regulation in those with reduced response to capecitabine/gemcitabine, and pathways associated with cell cycle regulation in those with reduced response to palbociclib. Our study shows that PDO-based functional precision medicine is a feasible and effective strategy for MBC treatment optimization and customization.

Elacestrant in the treatment landscape of ER-positive, HER2-negative, ESR1-mutated advanced breast cancer: a contemporary narrative review

Introduction

Estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer with ESR1 mutations presents a significant therapeutic challenge due to its adaptive resistance mechanisms to chemotherapy, especially endocrine treatment. Elacestrant, a novel oral selective estrogen receptor degrader (SERD), has emerged as a promising agent in this treatment-resistant era.

Method

A comprehensive search was conducted on pivotal clinical trials, including the RAD1901-005 Trial, EMERALD TRIAL, ELIPSE, and ELEVATE, focusing on their methodologies, patient populations, treatment regimens, and outcomes.

Discussion

This narrative review describes the available preclinical and clinical evidence on elacestrant, focusing on its pharmacodynamics, pharmacokinetics, efficacy, and safety within the existing literature. Elacestrant has demonstrated excellent activity against ESR1 mutations associated with resistance to first-line endocrine therapies. Clinical trials have shown improved progression-free survival in patients with advanced ER+/HER2-, ESR1-mutated breast cancer. Safety profiles indicate a tolerable side effect spectrum consistent with other agents. Its oral bioavailability offers a convenient alternative to injectable SERDs, with potential implications for patient adherence and quality of life. The review also discusses the comparative efficacy of elacestrant relative to existing endocrine therapies and its possible use in combination regimens.

Conclusion

Ongoing clinical trials assessing elacestrant and other SERDs will yield data that might aid clinicians in determining the optimal selection and order of endocrine treatment drugs for ER+ breast cancer. The integration of targeted and immunotherapeutic agents with traditional chemotherapy represents a pivotal shift in Breast Cancer treatment, moving towards more personalized and effective regimens.

Brain metastasis risk prediction model in females with hormone receptor-positive breast cancer

BACKGROUND

Breast cancer is a leading cause of cancer-related deaths in females, and the hormone receptor-positive subtype is the most frequent. Breast cancer is a common source of brain metastases; therefore, we aimed to generate a brain metastases prediction model in females with hormone receptor-positive breast cancer.

METHODS

The primary cohort included 3,682 females with hormone receptor-positive breast cancer treated at a single center from May 2009 to May 2020. Patients were randomly divided into a training dataset (n = 2,455) and a validation dataset (n = 1,227). In the training dataset, simple logistic regression analyses were used to measure associations between variables and the diagnosis of brain metastases and to build multivariable models. The model with better calibration and discrimination capacity was tested in the validation dataset to measure its predictive performance.

RESULTS

The variables incorporated in the model included age, tumor size, axillary lymph node status, clinical stage at diagnosis, HER2 expression, Ki-67 proliferation index, and the modified Scarff-Bloom-Richardson grade. The area under the curve was 0.81 (95 % CI 0.75-0.86), p < 0.001 in the validation dataset. The study presents a guide for the clinical use of the model.

CONCLUSION

A brain metastases prediction model in females with hormone receptor-positive breast cancer helps assess the individual risk of brain metastases.

Design and synthesis of phosphoryl-substituted steroidal pyridazines (Pho-STPYRs) as potent estrogen receptor alpha inhibitors: targeted treatment of hormone-dependent breast cancer cells

Estrogen receptor alpha (ERα) is an important target for the discovery of new therapeutic drugs against hormone-dependent breast cancer. A series of phosphoryl-substituted steroidal pyridazines (Pho-STPYRs) were synthesized and biologically evaluated as potent ERα inhibitors. Pho-STPYRs showed cytotoxicity against breast cancer cells with IC50 values of 5.9 μM and higher. Pho-STPYRs 33 and 34 [IC50 (MCF7) = 6.5 and 5.9 μM, respectively] were found to block the expression of ERα, the main driver of breast cancer growth, and modulate the ERK, cyclin D1, and CDK4 pathways. Compound 34 showed selectivity, anti-estrogenic potency and high antiproliferative efficacy in combination with the AKT inhibitor. Molecular docking was used to more accurately define the binding mode of lead compounds 33 and 34 to ERα. The selectivity analysis showed that lead compounds 33 and 34 produce no effects on cytochromes P450, including CYP7A1, CYP7B1, CYP17A1, CYP19A1, and CYP21A2. In a word, Pho-STPYRs 33 and 34 are promising ERα inhibitors for the treatment of hormone-dependent breast cancer.

Molecular and Pathobiology of Canine Mammary Tumour: Defining a Translational Model for Human Breast Cancer

Canine mammary tumours (CMT) have histological, clinicopathological and molecular resemblances to human breast cancer (HBC), positioning them as viable models for studying the human disease. CMT initiation and progression occur spontaneously in immune-competent animals, which challenge the suggested limitations of genetically modified mice, also enabling the evaluation of immunotherapies in canine patients. Dogs have shorter life expectancy compared to humans, and cancer advances more rapidly in this species. This makes it possible to perform studies about the clinical efficacy of new therapeutic modalities in a much shorter time than in human patients. The identification of biomarkers for tumour subtypes, progression and treatment response paves the way for the development of novel therapeutic and diagnostic approaches. This review addresses the similarities between CMT and HBC and the molecular signatures identified in CMT samples that have been explored to date. We proposed a detailed molecular exploration of the CMT stroma using state-of-the-art methods in transcriptomics and proteomics. Using CMT as an analog for HBC not only helps to understand the complexities of the disease, but also to advance comparative oncology to the next level to prove the claim of dogs as a valid translational model.

A Comprehensive Review of HER2 in Cancer Biology and Therapeutics

Human epidermal growth factor receptor 2 (HER2), a targetable transmembrane glycoprotein receptor of the epidermal growth factor receptor (EGFR) family, plays a crucial role in cell proliferation, survival, and differentiation. Aberrant HER2 signaling is implicated in various cancers, particularly in breast and gastric cancers, where HER2 overexpression or amplification correlates with aggressive tumor behavior and poor prognosis. HER2-activating mutations contribute to accelerated tumorigenesis and metastasis. This review provides an overview of HER2 biology, signaling pathways, mechanisms of dysregulation, and diagnostic approaches, as well as therapeutic strategies targeting HER2 in cancer. Understanding the intricate details of HER2 regulation is essential for developing effective targeted therapies and improving patient outcomes.

Efficacy and safety of neoadjuvant therapy for HR-positive/HER2-negative early breast cancer: a Bayesian network meta-analysis

BACKGROUND

Neoadjuvant treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer is controversial and requires a comprehensive analysis for optimal therapy assessment. Therefore, a two-step Bayesian network meta-analysis (NMA) was performed to compare the efficacy and safety of different neoadjuvant regimens.

RESEARCH DESIGN AND METHODS

Phase II/III randomized clinical trials comparing various neoadjuvant therapies for HR+/HER2- breast cancer were included. NMA and pairwise meta-analyses were conducted using Stata (version 14), R (version 4.2.3), and Review Manager 5.4.

RESULTS

Twenty-eight studies (5,625 patients) were eligible. NMA of objective response rate (ORR) indicated the highest SUCRA for chemotherapy (CT) and chemotherapy with anthracycline (CT(A)). Pathologic complete response (PCR) NMA demonstrated significant PCR improvement with chemotherapy regimens containing programmed cell death protein-1 and programmed cell death ligand-1 inhibitors (PD-1i/PD-L1i) and poly ADP-ribose polymerase inhibitors (PARPi). Combined analysis considering both the ORR and safety highlighted CT(A)'s efficacy and toxicity balance.

CONCLUSIONS

CT(A) and CT showed improved ORR compared with alternative regimens. CT(A) combined with PD-1/PD-L1 or PARP inhibitors significantly increased PCR rates. Comprehensive assessment of both ORR and safety indicated that CT(A) represents an optimal neoadjuvant therapy for HR+/HER2- breast cancer, whereas AI + CDK4/6 inhibitors rank solely behind chemotherapy.

REGISTRATION

PROSPERO Registration: CRD42024538948. International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY) registration number INPLASY202440092.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

DREAM On, DREAM Off: A Review of the Estrogen Paradox in Luminal A Breast Cancers

It is generally assumed that all estrogen-receptor-positive (ER+) breast cancers proliferate in response to estrogen and, therefore, examples of the estrogen-induced regression of ER+ cancers are paradoxical. This review re-examines the estrogen regression paradox for the Luminal A subtype of ER+ breast cancers. The proliferative response to estrogen is shown to depend on the level of ER. Mechanistically, a window of opportunity study of pre-operative estradiol suggested that with higher levels of ER, estradiol could activate the DREAM-MMB (Dimerization partner, Retinoblastoma-like proteins, E2F4, and MuvB-MYB-MuvB) pathway to decrease proliferation. The response of breast epithelium and the incidence of breast cancers during hormonal variations that occur during the menstrual cycle and at the menopausal transition, respectively, suggest that a single hormone, either estrogen, progesterone or androgen, could activate the DREAM pathway, leading to reversible cell cycle arrest. Conversely, the presence of two hormones could switch the DREAM-MMB complex to a pro-proliferative pathway. Using publicly available data, we examine the gene expression changes after aromatase inhibitors and ICI 182,780 to provide support for the hypothesis. This review suggests that it might be possible to integrate all current hormonal therapies for Luminal A tumors within a single theoretical schema.

Retrospective registry of patients with locally advanced/metastatic HR+/HER2- breast cancer treated in clinical practice in Andalusia

BACKGROUND

Limited data are available regarding the real-world effectiveness and safety of Cyclin Dependent Kinase 4/6 inhibitor (CDK4/6i) (palbociclib/ribociclib) just as a first-line treatment for patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR + /HER2‒) metastatic breast cancer (MBC).

OBJECTIVE

To assess whether clinical or demographic characteristics limit access to first-line CDK4/6i treatment in clinical practice in the Autonomous Community of Andalusia (Spain) between November 2017 and April 2020. In addition, effectiveness will be described in an exploratory analysis.

METHODS

Physicians from 12 centers participated in selecting demographic and clinical characteristics, treatment, and outcome data from women with HR + /HER2- MBC treated with or without CDK4/6i in addition to hormonal in the first-line setting, in a 3:1 proportion. Kaplan-Meier analysis estimated progression-free rates (PFRs) and survival rates (SRs).

RESULTS

A total of 212 patients were included, of whom 175 (82.5%) were in the CDK4/6i treatment group and 37 (17.5%) were in the non-CDK4/6i treatment group (control group). Patients in the CDK 4/6i treatment group were younger (p = 0.0011), the biopsies of the metastatic site at the moment of the relapse were most commonly performed (p = 0.0454), and had multiple metastatic sites (p = 0.0025). The clinical benefit rate (CBR) was 82.3% in the CDK4/6i group and 67.8% in the control group. Median time to a progression event or death (PFS) was 20.4 months (95%CI 15.6-28) in the CDK4/6i group and 12.1 months (95%CI 7.9-not reached) in the control group.

CONCLUSIONS

Younger patients, biopsies of metastatic disease and with multiple metastatic sites were more frequently treated with CDK4/6i in our daily clinical practice.

Circulating tumor DNA: from discovery to clinical application in breast cancer

Breast cancer (BC) stands out as the cancer with the highest incidence of morbidity and mortality among women worldwide, and its incidence rate is currently trending upwards. Improving the efficiency of breast cancer diagnosis and treatment is crucial, as it can effectively reduce the disease burden. Circulating tumor DNA (ctDNA) originates from the release of tumor cells and plays a pivotal role in the occurrence, development, and metastasis of breast cancer. In recent years, the widespread application of high-throughput analytical technology has made ctDNA a promising biomarker for early cancer detection, monitoring minimal residual disease, early recurrence monitoring, and predicting treatment outcomes. ctDNA-based approaches can effectively compensate for the shortcomings of traditional screening and monitoring methods, which fail to provide real-time information and prospective guidance for breast cancer diagnosis and treatment. This review summarizes the applications of ctDNA in various aspects of breast cancer, including screening, diagnosis, prognosis, treatment, and follow-up. It highlights the current research status in this field and emphasizes the potential for future large-scale clinical applications of ctDNA-based approaches.

Progression from ductal carcinoma in situ to invasive breast cancer: molecular features and clinical significance

Ductal carcinoma in situ (DCIS) represents pre-invasive breast carcinoma. In untreated cases, 25-60% DCIS progress to invasive ductal carcinoma (IDC). The challenge lies in distinguishing between non-progressive and progressive DCIS, often resulting in over- or under-treatment in many cases. With increasing screen-detected DCIS in these years, the nature of DCIS has aroused worldwide attention. A deeper understanding of the biological nature of DCIS and the molecular journey of the DCIS-IDC transition is crucial for more effective clinical management. Here, we reviewed the key signaling pathways in breast cancer that may contribute to DCIS initiation and progression. We also explored the molecular features of DCIS and IDC, shedding light on the progression of DCIS through both inherent changes within tumor cells and alterations in the tumor microenvironment. In addition, valuable research tools utilized in studying DCIS including preclinical models and newer advanced technologies such as single-cell sequencing, spatial transcriptomics and artificial intelligence, have been systematically summarized. Further, we thoroughly discussed the clinical advancements in DCIS and IDC, including prognostic biomarkers and clinical managements, with the aim of facilitating more personalized treatment strategies in the future. Research on DCIS has already yielded significant insights into breast carcinogenesis and will continue to pave the way for practical clinical applications.

Therapeutic significance of long noncoding RNAs in estrogen receptor-positive breast cancer

About 70% of cases of breast cancer are compromised by Estrogen-positive breast cancer. Through its regulation of several processes, including cell proliferation, cell cycle progression, and apoptosis, Estrogen signaling plays a pivotal role in the genesis and progression of this particular kind of breast cancer. One of the best treatment strategies for treating Estrogen-positive breast cancer is blocking Estrogen signaling. However, patients' treatment failure is mainly caused by the emergence of resistance and metastases, necessitating the development of novel therapeutic targets. Numerous studies have shown long noncoding RNAs (lncRNAs) to play a role in Estrogen-mediated carcinogenesis. These lncRNAs interact with co-regulators and the Estrogen signaling cascade components, primarily due to Estrogen activation. Vimentin and E-cadherin are examples of epithelial-to-mesenchymal transition markers, and they regulate genes involved in cell cycle progression, such as Cyclins, to affect the growth, proliferation, and metastasis of Estrogen-positive breast cancer. Furthermore, a few of these lncRNAs contribute to developing resistance to chemotherapy, making them more desirable targets for enhancing results. Thus, to shed light on the creation of fresh approaches for treating this cancer, this review attempts to compile recently conducted studies on the relationship between lncRNAs and the advancement of Estrogen-positive breast cancer.

RBP7 functions as a tumor suppressor in HR + breast cancer by inhibiting the AKT/SREBP1 pathway and reducing fatty acid

BACKGROUND

Increasing evidence proves that RBP7 plays a significant role in breast cancer (BC). The present study was aimed to investigate the mechanism of RBP7.

METHODS

Western Blotting and qRT-PCR were performed for evaluating the expression levels. CCK8, colony forming, xenograft mouse model, wound healing and transwell assays were conducted to examine cell ability of proliferation, invasion and migration. Nile red staining and Oil red O staining were used for testing the lipid.

RESULTS

RBP7 was related to overall survival (OS) in patients with HR + BC. RBP7 protein was significantly decreased in HR + BC tissues and cells. RBP7 suppressed HR + BC cell proliferation in vitro and in vivo, and inhibited migration and invasion. RBP7 reduced fatty acid in HR + BC cells by inhibiting the AKT/SREBP1 pathway.

CONCLUSIONS

RBP7 may function as a tumor suppressor in HR + BC by inhibiting the AKT/SREBP1 pathway and reducing fatty acid.

Invasive papillary carcinoma of the breast

Invasive papillary carcinoma is a rare form of breast cancer that is more likely to occur in postmenopausal women. Previous studies have been limited to case reports and small retrospective studies, leading to low awareness of this type of tumor and difficult clinical management. According to the available literature, invasive papillary carcinoma exhibits unique pathological features and biological behaviors. Invasive papillary carcinoma is mostly luminal type, with a low rate of lymph node metastasis, which underlies its favorable prognosis. The effectiveness of adjuvant therapy in reducing tumor burden and improving prognosis in patients with invasive papillary carcinoma remains uncertain. Due to the rarity of the lesion, conducting prospective clinical trials is impractical. The use of biological models, such as organoids, can help alleviate the impact of the scarcity of this condition on research. In addition, invasive papillary carcinoma is affected by specific genomic events, and more extensive studies of gene expression profiling may provide molecular-level insights to make optimal therapeutic decisions.

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.

Fine-Tuning Adjuvant Endocrine Therapy for Early-Stage Breast Cancer: An Expert Consensus on Open Issues for Future Research

After decades of research, improving the efficacy of adjuvant endocrine therapy (ET) for early-stage breast cancer becomes increasingly difficult. Beyond technological breakthroughs and the availability of new classes of drugs, further improvement of adjuvant ET will require applying a rigorous research approach in poorly investigated areas. We critically discuss some key principles that should inform future research to improve ET efficacy, including identifying specific subgroups of patients who can benefit from escalating or de-escalating approaches, optimizing available and new treatment strategies for different clinical contexts, and dissecting the direct and indirect biological effects of therapeutic interventions. Four main issues regarding adjuvant ET were identified as relevant areas, where a better application of such principles can provide positive results in the near future: (i) tailoring the optimal duration of adjuvant ET, (ii) optimizing ovarian function suppression for premenopausal women, (iii) dissecting the biological effects of estrogen receptor manipulation, and (iv) refining the selection of patients to candidate for treatments escalation.

The Role of Ki-67 in HR+/HER2- Breast Cancer: A Real-World Study of 956 Patients

Objective

This study determined the cut-off value of Ki-67 expression and discussed the interaction between Ki-67 and histological grade, further explored the prognostic role of Ki-67 in hormone receptor-positive and human epidermal growth factor receptor 2 negative (HR+/HER2-) breast cancer;.

Materials and Methods

We assessed the Ki-67 expression of 956 patients with HR+/HER2 breast cancer diagnosed in the General Hospital of Ningxia Medical University from 2015 to 2019 by immunohistochemistry (IHC), The disease-free survival (DFS) was defined as the time from postoperative to the first local recurrence, distant metastasis or death of the disease. The follow-up by means of inpatient or outpatient medical records and telephone.

Results

22.5% was used as the cut-off for low/high Ki-67 expression in HR+/HER2- breast cancer. Compared with the value of 14%, which is commonly used in clinic at present, the consistency of the two values is moderate (Kappa = 0.484, P<0.001). The expression of Ki-67 was increased with the grade. (Median: G1:10%; G2:20%; G3:40%. Mean: G1:13%; G2:23%; G3:39%, P <0.001). Survival analysis was based on all patients for a median of 51 months (24-89 months), 63 cases had recurrence or metastasis during the follow-up, which 21 cases had low expression of Ki-67 and 42 cases had high expression. The patients with Ki-67 ≥ 22.5% had a 2.969 higher risk of early recurrence and metastasis than the patients with Ki-67 < 22.5%. There were 4 cases of local recurrence, 7 cases of regional lymph node metastasis, and 52 cases of distant metastasis in all patients, the common distant metastases were bone, liver, and lung, and rare metastases were adrenal gland, bone marrow, and pericardium.

Conclusion

In HR+/HER2- breast cancer, patients with Ki-67 > 22.5% have a worse prognosis and are more likely to have early recurrence and metastasis.

Factors Associated With Node-Positive Disease in Estrogen Receptor-Positive Breast Cancer Patients

INTRODUCTION

Larger tumor size and shorter tumor-to-nipple distance at diagnosis are associated with greater risk of lymph node involvement in breast cancer. However, the relationship between receptor subtype status and lymph node metastasis remains unclear. Our objective was to examine the association between primary tumor size, location, and nodal metastasis across estrogen receptor (ER)+/ progesterone receptor (PR)+/ human epidermal growth factor receptor 2 (HER2)-, ER+/PR-/HER2-, ER+/PR+/HER2+, and ER+/PR-/HER2+ tumors.

METHODS

A single-institution retrospective chart review was conducted of breast cancer patients diagnosed between 1998 and 2019 who underwent nodal evaluation during primary surgery. Neoadjuvant chemotherapy, pure ductal carcinoma in situ, inflammatory, recurrent, metastatic, bilateral, multicentric, and multifocal disease were excluded. Descriptive statistics (proportions and frequencies for categorical variables and medians [Q1-Q3] for continuous variables) were used to summarize patient characteristics. Kruskal-Wallis test was applied to test the association of outcome variables and continuous variables. Chi-square test or Fisher exact test was applied to test the association of outcome variables and categorical variables.

RESULTS

Six hundred eighteen ER + patients had a median tumor size of 1.7 cm (1.1-2.5 cm). Two hundred ninety six out of 618 (47.9%) were node-positive and 188/618 (30.4%) had axillary dissection. Eighty four point three percent of patients were ER+/PR+/HER2-, 6.31% were ER+/PR-/HER2-, 6.96% were ER+/PR+/HER2+, and 1.13% were ER+/PR-/HER2+. Median tumor size was significantly larger in node-positive cases compared to node-negative cases in ER+/PR+/HER2-, ER+/PR+/HER2+, and ER+/PR-/HER2- subgroups. In ER+/PR+/HER2-patients, median tumor-nipple distance was significantly shorter in node-positive patients compared to node-negative patients. Upper outer quadrant location was significantly associated with nodal positivity in ER+/PR-/HER2- patients.

CONCLUSIONS

Across ER + patients, the significance between tumor size, location, and lymph node positivity varied significantly when differentiating by PR and HER2 status.

Activity and safety of enobosarm, a novel, oral, selective androgen receptor modulator, in androgen receptor-positive, oestrogen receptor-positive, and HER2-negative advanced breast cancer (Study G200802): a randomised, open-label, multicentre, multinational, parallel design, phase 2 trial

BACKGROUND

The androgen receptor is a tumour suppressor in oestrogen receptor-positive breast cancer. The activity and safety of enobosarm, an oral selective androgen receptor modulator, was evaluated in women with oestrogen receptor (ER)-positive, HER2-negative, and androgen receptor (AR)-positive disease.

METHODS

Women who were postmenopausal (aged ≥18 years) with previously treated ER-positive, HER2-negative, locally advanced or metastatic breast cancer with an Eastern Cooperative Oncology Group performance status of 0-2 were enrolled in a randomised, open-label, multicentre, multinational, parallel design, phase 2 trial done at 35 cancer treatment centres in nine countries. Participants were stratified on the setting of immediately preceding endocrine therapy and the presence of bone-only metastasis and randomly assigned (1:1) to 9 mg or 18 mg oral enobosarm daily using an interactive web response system. The primary endpoint was clinical benefit rate at 24 weeks in those with centrally confirmed AR-positive disease (ie, the evaluable population). This trial is registered with ClinicalTrials.gov (NCT02463032).

FINDINGS

Between Sept 10, 2015, and Nov 28, 2017, 136 (79%) of 172 patients deemed eligible were randomly assigned to 9 mg (n=72) or 18 mg (n=64) oral enobosarm daily. Of these 136 patients, 102 (75%) patients formed the evaluable population (9 mg, n=50; 18 mg, n=52). The median age was 60·5 years (IQR 52·3-69·3) in the 9 mg group and 62·5 years (54·0-69·3) in the 18 mg group. The median follow-up was 7·5 months (IQR 2·9-14·1). At 24 weeks, 16 (32%, 95% CI 20-47) of 50 in the 9 mg group and 15 (29%, 17-43) of 52 in the 18 mg group had clinical benefit. Six (8%) of 75 patients who received 9 mg and ten (16%) of 61 patients who received 18 mg had grade 3 or grade 4 drug-related adverse events, most frequently increased hepatic transaminases (three [4%] of 75 in the 9 mg group and two [3%] of 61 in the 18 mg group), hypercalcaemia (two [3%] and two [3%]), and fatigue (one [1%] and two [3%]). Four deaths (one in the 9 mg group and three in the 18 mg group) were deemed unrelated to the study drug.

INTERPRETATION

Enobosarm has anti-tumour activity in patients with ER-positive, HER2-negative advanced breast cancer, showing that AR activation can result in clinical benefit, supporting further clinical investigation of selective AR activation strategies for the treatment of AR-positive, ER-positive, HER2-negative advanced breast cancer.

FUNDING

GTx.

Adjuvant Chemotherapy in Premenopausal Patients With Hormone-Positive Breast Cancer With a Recurrence Score of 16-25: A Retrospective Analysis Using the National Cancer Database

PURPOSE

Results from the TAILORx trial revealed that the use of adjuvant chemotherapy along with endocrine therapy had no survival advantage in patients with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2-negative (HER2-), node-negative (N0) breast cancer (BC) with an intermediate (11-25) 21-gene recurrence score (RS) in the overall population. However, in patients under age 50 years, adjuvant chemotherapy demonstrated a progression-free survival benefit when the RS ranged from 16-25. We studied this cohort with the population-based national database.

METHODS

The 2010-2018 National Cancer Database was used to include patients with BC age 18-50 years, N0, M0, RS 16-25, ER+/progesterone receptor±, and HER2-. Patients were divided into two groups on the basis of adjuvant chemotherapy use, and the survival between them was compared.

RESULTS

Adjuvant chemotherapy use was noted in 4,808/15,792 (30.45%) patients. Median RS was 18 and 21 in patients without and with adjuvant chemotherapy, respectively. Factors associated with adjuvant chemotherapy use were higher T stage, poor and moderately differentiated tumors, age <40 years, care at an academic center, Caucasian race, patients undergoing mastectomy, regional lymph node surgery, and radiation therapy. Kaplan-Meier survival at 10 years was better with adjuvant chemotherapy (96.2% v 91.6%). Patients without adjuvant chemotherapy had more adverse outcomes (hazard ratio [HR], 1.683 [95% CI, 1.392 to 2.036]; P < .0001). Subgroup analysis showed that the benefit was significant in patients with RS scores 21-25 (HR, 1.953 [95% CI, 1.295 to 2.945]), ductal histology (HR, 1.521 [95% CI, 1.092 to 2.118]), Caucasian race (HR, 1.655 [95% CI, 1.180 to 2.322]), and 41-50 years age group (HR, 1.732 [95% CI, 1.244 to 2.411]).

CONCLUSION

Our study showed an overall survival benefit for adjuvant chemotherapy use in patients with ER-positive, N0 premenopausal BC patients, age less than 50 years, with an intermediate RS score, particularly 21-25.

A novel bystander effect in tamoxifen treatment: PPIB derived from ER+ cells attenuates ER- cells via endoplasmic reticulum stress-induced apoptosis

Tamoxifen (TAM) is the frontline therapy for estrogen receptor-positive (ER+) breast cancer in premenopausal women that interrupts ER signaling. As tumors with elevated heterogeneity, amounts of ER-negative (ER-) cells are present in ER+ breast cancer that cannot be directly killed by TAM. Despite complete remissions have been achieved in clinical practice, the mechanism underlying the elimination of ER- cells during TAM treatment remains an open issue. Herein, we deciphered the elimination of ER- cells in TAM treatment from the perspective of the bystander effect. Markable reductions were observed in tumorigenesis of ER- breast cancer cells by applying both supernatants from TAM-treated ER+ cells and a transwell co-culture system, validating the presence of a TAM-induced bystander effect. The major antitumor protein derived from ER+ cells, peptidyl-prolyl cis-trans isomerase B (PPIB), is the mediator of the TAM-induced bystander effect identified by quantitative proteomics. The attenuation of ER- cells was attributed to activated BiP/eIF2α/CHOP axis and promoted endoplasmic reticulum stress (ERS)-induced apoptosis, which can also be triggered by PPIB independently. Altogether, our study revealed a novel TAM-induced bystander effect in TAM treatment of ER+ breast cancer, raising the possibility of developing PPIB as a synergistic antitumor agent or even substitute endocrine therapy.

Aromatase Inhibitor Therapy Increases the Risk of New-Onset Atrial Fibrillation in Patients With Breast Cancer

Background

Previous studies suggest that aromatase inhibitors (AIs) increase the risk of adverse cardiovascular events and cardiac arrhythmias in patients with breast cancer, but it is unclear whether AIs also increase the risk of new-onset atrial fibrillation (AF).

Objectives

The purpose of this study was to investigate whether the use of AIs was associated with an increased risk of new-onset AF in patients with breast cancer.

Methods

We performed a retrospective analysis involving 5,707 patients with breast cancer (mean age 63.9 ± 11.2 years and 99.9% women) who received adjunctive hormone therapy with an AI (AI group, n = 4,878) or tamoxifen (tamoxifen group, n = 829) in Hong Kong between January 1, 1999, and December 31, 2020. After propensity score matching, there were 1,658 and 829 patients with balanced characteristics in the AI group and tamoxifen group, respectively.

Results

After 8,863 patient-years of follow-up, patients who were prescribed AI had a trend toward more new-onset arrhythmias compared with those prescribed tamoxifen (0.62 vs 0.30 per 100 patient-years; crude HR: 2.05; P = 0.053). The difference in arrhythmic risk was mainly driven by a higher incidence rate of new-onset AF in the AI group (0.59 vs 0.27 per 100 patient-years; crude HR: 2.18; P = 0.046). The use of AIs was confirmed to be an independent risk factor for new-onset AF on multivariate analysis (adjusted HR: 2.75; P = 0.01).

Conclusions

Among breast cancer patients prescribed adjunctive hormonal therapy, AI was associated with an increased risk of new-onset AF. Regular surveillance for new-onset AF should be considered in breast cancer patients treated with an AI.

Is controlled ovarian stimulation safe in patients with hormone receptor-positive breast cancer receiving neoadjuvant chemotherapy?

INTRODUCTION

Controlled ovarian stimulation (COS) for oocyte/embryo cryopreservation is the method of choice for fertility preservation (FP) in young patients diagnosed with early-stage breast cancer (eBC). Nevertheless, some challenges still question its role, particularly in the neoadjuvant setting, where concerns arise about potential delay in the onset of anticancer treatment, and in hormone receptor-positive (HR+) disease, as cancer cells may proliferate under the estrogenic peak associated with stimulation. Therefore, this review aims to examine the available evidence on the safety of COS in eBC patients eligible for neoadjuvant treatment (NAT), particularly in HR+ disease.

METHODS

A comprehensive literature search was conducted to identify studies evaluating the feasibility and safety of COS in eBC and including patients referred to NAT and/or with HR+ disease. Time to NAT and survival outcomes were assessed.

RESULTS

Of the three matched cohort studies assessing the impact of COS on time to start NAT, only one reported a significant small delay in the cohort undergoing COS compared with the control group, whereas the other studies found no difference. Regarding survival outcomes, overall, no increased risk of recurrence or death was found, either in patients undergoing COS in the neoadjuvant setting regardless of HR expression or in HR+ disease regardless of the timing of COS relative to surgery. However, there are no data on the safety of COS in the specific combined scenario of HR+ disease undergoing NAT.

CONCLUSION

Neither the indication to NAT nor the HR positivity constitutes per se an a priori contraindication to COS. Shared decision making between clinicians and patients is essential to carefully weigh the risks and benefits in each individual case. Prospective studies designed to specifically investigate this issue are warranted.

International multidisciplinary consensus on the integration of radiotherapy with new systemic treatments for breast cancer: European Society for Radiotherapy and Oncology (ESTRO)-endorsed recommendations

Novel systemic therapies for breast cancer are being rapidly implemented into clinical practice. These drugs often have different mechanisms of action and side-effect profiles compared with traditional chemotherapy. Underpinning practice-changing clinical trials focused on the systemic therapies under investigation, thus there are sparse data available on radiotherapy. Integration of these new systemic therapies with radiotherapy is therefore challenging. Given this rapid, transformative change in breast cancer multimodal management, the multidisciplinary community must unite to ensure optimal, safe, and equitable treatment for all patients. The aim of this collaborative group of radiation, clinical, and medical oncologists, basic and translational scientists, and patient advocates was to: scope, synthesise, and summarise the literature on integrating novel drugs with radiotherapy for breast cancer; produce consensus statements on drug-radiotherapy integration, where specific evidence is lacking; and make best-practice recommendations for recording of radiotherapy data and quality assurance for subsequent studies testing novel drugs.

Reviewing the significance of dendritic cell vaccines in interrupting breast cancer development

Breast cancer is a heterogeneous disease and is the most prevalent cancer in women. According to the U.S breast cancer statistics, about 1 in every 8 women develop an invasive form of breast cancer during their lifetime. Immunotherapy has been a significant advancement in the treatment of cancer with multiple studies reporting favourable patient outcomes by modulating the immune response to cancer cells. Here, we review the significance of dendritic cell vaccines in treating breast cancer patients. We discuss the involvement of dendritic cells and oncodrivers in breast tumorigenesis, highlighting the rationale for targeting oncodrivers and neoantigens using dendritic cell vaccine therapy. We review different dendritic cell subsets and maturation states previously used to develop vaccines and suggest the use of DC vaccines for breast cancer prevention. Further, we highlight that the intratumoral delivery of type 1 dendritic cell vaccines in breast cancer patients activates tumor antigen-specific CD4+ T helper cell type 1 (Th1) cells, promoting an anti-tumorigenic immune response while concurrently blocking pro-tumorigenic responses. In summary, this review provides an overview of the current state of dendritic cell vaccines in breast cancer highlighting the challenges and considerations necessary for an efficient dendritic cell vaccine design in interrupting breast cancer development.

Mechanisms of Traditional Chinese medicine/natural medicine in HR-positive Breast Cancer: A comprehensive Literature Review

ETHNOPHARMACOLOGICAL RELEVANCE

With the emergence of endocrine resistance, the survival and good prognosis of HR-positive breast cancer (HR + BC) patients are threatened. As a common complementary and alternative therapy in cancer treatment, traditional Chinese medicine (TCM) has been widely used, and its internal mechanisms have been increasingly explored.

AIM OF THE REVIEW

In this review, the development status and achievements in understanding of the mechanisms related to the anti-invasion and anti-metastasis effects of TCM against HR + BC and the reversal of endocrine drug resistance by TCM in recent years have been summarized to provide ideas for antitumour research on the active components of TCM/natural medicine.

METHODS

We searched the electronic databases PubMed, Web of Science, and China National Knowledge Infrastructure database (CNKI) (from inception to July 2023) with the key words "HR-positive breast cancer" or "HR-positive breast carcinoma", "HR + BC" and "traditional Chinese medicine", "TCM", or "natural plant", "herb", etc., with the aim of elucidating the intrinsic mechanisms of traditional Chinese medicine and natural medicine in the treatment of HR + BC.

RESULTS

TCM/natural medicine monomers and formulas can regulate the expression of related genes and proteins through the PI3K/AKT, JAK2/STAT3, MAPK, Wnt and other signalling pathways, inhibit the proliferation and metastasis of HR + BC tumours, play a synergistic role in combination with endocrine drugs, and reverse endocrine drug resistance.

CONCLUSION

The wide variety of TCM/natural medicine components makes the research and development of new methods of TCM for BC treatments more selective and innovative. Although progress has been made on research on TCM/natural medicine, there are still many problems in clinical and basic experimental designs, and more in-depth scientific explorations and research are still needed.

Imaging Molecular Targets and Metabolic Pathways in Breast Cancer for Improved Clinical Management: Current Practice and Future Perspectives

Breast cancer is the most frequently diagnosed cancer and leading cause of cancer-related deaths worldwide. Timely decision-making that enables implementation of the most appropriate therapy or therapies is essential for achieving the best clinical outcomes in breast cancer. While clinicopathologic characteristics and immunohistochemistry have traditionally been used in decision-making, these clinical and laboratory parameters may be difficult to ascertain or be equivocal due to tumor heterogeneity. Tumor heterogeneity is described as a phenomenon characterized by spatial or temporal phenotypic variations in tumor characteristics. Spatial variations occur within tumor lesions or between lesions at a single time point while temporal variations are seen as tumor lesions evolve with time. Due to limitations associated with immunohistochemistry (which requires invasive biopsies), whole-body molecular imaging tools such as standard-of-care [18F]FDG and [18F]FES PET/CT are indispensable in addressing this conundrum. Despite their proven utility, these standard-of-care imaging methods are often unable to image a myriad of other molecular pathways associated with breast cancer. This has stimulated interest in the development of novel radiopharmaceuticals targeting other molecular pathways and processes. In this review, we discuss validated and potential roles of these standard-of-care and novel molecular approaches. These approaches' relationships with patient clinicopathologic and immunohistochemical characteristics as well as their influence on patient management will be discussed in greater detail. This paper will also introduce and discuss the potential utility of novel PARP inhibitor-based radiopharmaceuticals as non-invasive biomarkers of PARP expression/upregulation.

Therapeutic evolution in HR+/HER2- breast cancer: from targeted therapy to endocrine therapy

Breast cancer, a complex and varied disease, has four distinct subtypes based on estrogen receptor and human epidermal growth factor receptor 2 (HER2) levels, among which a significant subtype known as HR+/HER2-breast cancer that has spurred numerous research. The prevalence of breast cancer and breast cancer-related death are the most serious threats to women's health worldwide. Current progress in treatment strategies for HR+/HER2-breast cancer encompasses targeted therapy, endocrine therapy, genomic immunotherapy, and supplementing traditional methods like surgical resection and radiotherapy. This review article summarizes the current epidemiology of HR+/HER2-breast cancer, introduces the classification of HR+/HER2-breast cancer and the commonly used treatment methods. The mechanisms of action of various drugs, including targeted therapy drugs and endocrine hormone therapy drugs, and their potential synergistic effects are deeply discussed. In addition, clinical trials of these drugs that have been completed or are still in progress are included.

Efficacy of a physiotherapy, yoga and patient education programme for patients with breast cancer and hormone therapy-induced pain: a multicentre randomised study protocol (SKYPE 2)

INTRODUCTION

Osteoarticular pain is experienced by approximately 50% of patients with breast cancer under hormone therapy and can increase the risk of therapy discontinuation. Among complementary therapies, yoga has shown efficacy regarding reduction of fatigue, anxiety, pain due to hormone therapy and inflammation. Personalised patient education programmes increase engagement and motivation, and induce effective behavioural changes. The SKYPE programme, an integrated intervention combining physiotherapy, yoga and patient education, showed promising efficacy on hormone therapy-induced pain in a previous pilot study. In this study, we hypothesised that using theory-based patient education favour learning and practising 15 min of at-home yoga every day to decrease hormone therapy-induced pain.

METHODS AND ANALYSIS

This multicentre randomised study will assess the efficacy of the SKYPE programme on pain reduction compared with standard care in patients with breast cancer reporting osteoarticular pain due to hormone therapy. Main secondary objectives will describe pain evolution and characteristics, patient adhesion to yoga sessions and home practice, forward flexibility, quality of life, fatigue, anxiety and compliance to hormone therapy. Patients in the intervention group will participate in 1 weekly educational yoga session of 90 min for 6 weeks, supervised by physiotherapists (period 1). They will also perform daily at-home 15 min yoga sessions for 12 weeks, the total duration of the intervention (periods 1 and 2). Pain will be evaluated during physiotherapy check-ups at baseline (T0), at 6 weeks (T1) and at 12 weeks (T2).

ETHICS AND DISSEMINATION

This study was approved by the ethics committee (CPP Ile de France 8 on 22 June 2020). The results will be disseminated to patients and healthcare professionals, and published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT04457895.

A prospective study on tumour response assessment methods after neoadjuvant endocrine therapy in early oestrogen receptor-positive breast cancer

BACKGROUND

Neoadjuvant endocrine therapy (NET) in oestrogen receptor-positive (ER+) /HER2-negative (HER2-) breast cancer allows real-time evaluation of drug efficacy as well as investigation of the biological and molecular changes that occur after estrogenic deprivation. Clinical and pathological evaluation after NET may be used to obtain prognostic and predictive information of tumour response to decide adjuvant treatment. In this setting, clinical scales developed to evaluate response after neoadjuvant chemotherapy are not useful and there are not validated biomarkers to assess response to NET beyond Ki67 levels and preoperative endocrine prognostic index score (mPEPI).

METHODS

In this prospective study, we extensively analysed radiological (by ultrasound scan (USS) and magnetic resonance imaging (MRI)) and pathological tumour response of 104 postmenopausal patients with ER+ /HER2- resectable breast cancer, treated with NET for a mean of 7 months prior to surgery. We defined a new score, tumour cellularity size (TCS), calculated as the product of the residual tumour cellularity in the surgical specimen and the tumour pathological size.

RESULTS

Our results show that radiological evaluation of response to NET by both USS and MRI underestimates pathological tumour size (path-TS). Tumour size [mean (range); mm] was: path-TS 20 (0-80); radiological-TS by USS 9 (0-31); by MRI: 12 (0-60). Nevertheless, they support the use of MRI over USS to clinically assess radiological tumour response (rad-TR) due to the statistically significant association of rad-TR by MRI, but not USS, with Ki67 decrease (p = 0.002 and p = 0.3, respectively) and mPEPI score (p = 0.002 and p = 0.6, respectively). In addition, we propose that TCS could become a new tool to standardize response assessment to NET given its simplicity, reproducibility and its good correlation with existing biomarkers (such as ΔKi67, p = 0.001) and potential added value.

CONCLUSION

Our findings shed light on the dynamics of tumour response to NET, challenge the paradigm of the ability of NET to decrease surgical volume and point to the utility of the TCS to quantify the scattered tumour response usually produced by endocrine therapy. In the future, these results should be validated in independent cohorts with associated survival data.

A Research Protocol for a Phase II Single-Arm Clinical Trial Assessing the Feasibility and Efficacy of Neoadjuvant Anastrozole in Patients With Luminal Breast Cancer and Low Proliferative Index: The ANNE Trial

INTRODUCTION

Neoadjuvant endocrine therapy (NET) is recommended for the treatment of invasive breast cancer (BC), particularly luminal subtypes, in locally advanced stages. Previous randomized studies have demonstrated the benefits of aromatase inhibitors in this context. However, NET is typically reserved for elderly or frail patients who may not tolerate neoadjuvant chemotherapy. Identifying non-responsive patients early and extending treatment for responsive ones would be ideal, yet optimal strategies are awaited.

AIMS

This non-randomized phase 2 clinical trial aims to assess NET feasibility and efficacy in postmenopausal stage II and III luminal BC patients, identifying predictive therapeutic response biomarkers. Efficacy will be gauged by patients with Ki67 ≤ 10% after 4 weeks and Preoperative Endocrine Prognostic Index (PEPI) scores 0 post-surgery. Study feasibility will be determined by participation acceptance rate (recruitment rate ≥50%) and inclusion rate (>2 patients/month).

METHODS

Postmenopausal women with luminal, HER2-tumors in stages II and III undergo neoadjuvant anastrozole treatment, evaluating continuing NET or receiving chemotherapy through early Ki67 analysis after 2 to 4 weeks. The study assesses NET extension for up to 10 months, using serial follow-ups with standardized breast ultrasound and clinical criteria-based NET suspension. Clinical and pathological responses will be measured overall and in the luminal tumor A subgroup. Toxicity, health-related quality of life, and circulating biomarkers predicting early NET response will also be evaluated.

Cost-effectiveness analysis of elacestrant versus standard endocrine therapy for second-/third-line treatment of patients with HR+/HER2- advanced or metastatic breast cancer: a US payer perspective

Background

This study evaluated the cost-effectiveness of elacestrant (ELA) and standard-of-care (SOC) as second-/third-line treatment for pretreated estrogen receptor (ER)- positive/human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer (A/MBC) in the US.

Methods

The 3 health states partitioned survival model (PSM) was conducted from the perspective of the US third-party payers. The time horizon for the model lasted 10 years. Effectiveness and safety data were derived from the EMERALD trial (NCT03778931). Costs were derived from the pricing files of Medicare and Medicaid Services, and utility values were derived from published studies. One-way sensitivity analysis as well as probabilistic sensitivity analysis were performed to observe model stability.

Result

ELA led to an incremental cost-effectiveness ratio (ICER) of $8,672,360/quality-adjusted life year (QALY) gained compared with SOC in the overall population and $2,900,560/QALY gained compared with fulvestrant (FUL) in the ESR1(estrogen receptor 1) mutation subgroup. The two ICERs of ELA were significantly higher than the willingness-to-pay (WTP) threshold values of $150,000/QALY.

Conclusions

ELA was not cost-effective for the second-/third-line treatment of patients with ER+/HER2-A/MBC compared with SOC in the US.

Deep learning-enabled breast cancer endocrine response determination from H&E staining based on ESR1 signaling activity

Estrogen receptor (ER) positivity by immunohistochemistry has long been a main selection criterium for breast cancer patients to be treated with endocrine therapy. However, ER positivity might not directly correlate with activated ER signaling activity, which is a better predictor for endocrine therapy responsiveness. In this study, we investigated if a deep learning method using whole-slide H&E-stained images could predict ER signaling activity. First, ER signaling activity score was determined using RNAseq data available from each of the 1082 breast cancer samples in the TCGA Pan-Cancer dataset based on the Hallmark Estrogen Response Early gene set from the Molecular Signature Database (MSigDB). Then the processed H&E-stained images and ER signaling activity scores from a training cohort were fed into ResNet101 with three additional fully connected layers to generate a predicted ER activity score. The trained models were subsequently applied to an independent testing cohort. The result demonstrated that ER + /HER2- breast cancer patients with a higher predicted ER activity score had longer progression-free survival (p = 0.0368) than those with lower predicted ER activity score. In conclusion, a convolutional deep neural network can predict prognosis and endocrine therapy response in breast cancer patients based on whole-slide H&E-stained images. The trained models were found to robustly predict the prognosis of ER + /HER2- patients. This information is valuable for patient management, as it does not require RNA-seq or microarray data analyses. Thus, these models can reduce the cost of the diagnosis workflow if such information is required.

Bibliometric analysis and visualization of endocrine therapy for breast cancer research in the last two decade

Background

Breast cancer endocrine therapy research has become a crucial domain in oncology since hormone receptor-positive breast cancers have been increasingly recognized, and targeted therapeutic interventions have been advancing over the past few years. This bibliometric analysis attempts to shed light on the trends, dynamics, and knowledge hotspots that have shaped the landscape of breast cancer endocrine therapy research between 2003 and 2022.

Methods

In this study, we comprehensively reviewed the scientific literature spanning the above-mentioned period, which included publications accessible through the database of the Web of Science (WOS) and the National Center for Biotechnology Information (NCBI). Next, a systematic and data-driven analysis supported by sophisticated software tools was conducted, such that the core themes, prolific authors, influential journals, prominent countries, and critical citation patterns in the relevant research field can be clarified.

Results

A continuous and substantial expansion of breast cancer endocrine therapy research was revealed over the evaluated period. A total of 1,317 scholarly articles were examined. The results of the analysis suggested that research on endocrine therapy for breast cancer has laid a solid basis for the treatment of hormone receptor-positive breast cancer. From a geographical perspective, the US, the UK, and China emerged as the most active contributors, illustrating the global impact of this study. Furthermore, our analysis delineated prominent research topics that have dominated the discourse in the past two decades, including drug therapy, therapeutic efficacy, molecular biomarkers, and hormonal receptor interactions.

Conclusion

This comprehensive bibliometric analysis provides a panoramic view of the ever-evolving landscape of breast cancer endocrine therapy research. The findings highlight the trajectory of past developments while signifying an avenue of vast opportunities for future investigations and therapeutic advancements. As the field continues to burgeon, this analysis will provide valuable guidance for to researchers toward pertinent knowledge hotspots and emerging trends, which can expedite the discoveries in the realm of breast cancer endocrine therapy.

Adoption and use of immunotherapy in breast cancer management in Africa: barriers and prospect - a narrative review

Breast cancer (BC) is the world's most frequently diagnosed cancer in women, with 7.8 million women diagnosed with BC in the past 5 years. BC has the highest incidence rate of all cancers in women worldwide (1.67 million), accounting for over 500 000 deaths annually. In Africa, BC accounts for 28% of all cancers and 20% of all cancer deaths in women. The African continent has recorded an alarming increase in incidence, with the highest mortality rate globally. Despite BC being a major health concern in Africa, there is limited access to adequate healthcare services to combat the growing need. Immunotherapy, a promising treatment approach that harnesses the immune system's power to fight cancer, has shown great potential in BC management. However, in the face of the growing body of evidence supporting its effectiveness, the adoption and use of immunotherapy in BC management in Africa remain limited. Hence, this review aimed to explore the barriers and prospects of immunotherapy adoption and use in BC management in Africa. A comprehensive search across various databases and sources using specific keywords related to immunotherapy and BC to achieve the study aim was conducted. The criteria for including data in the study were based on relevance and availability in English, with no publication year restrictions. The collected data underwent narrative analysis, supplemented by information from sources like country reports, newsletters, commentaries, policy briefs, and direct Google searches. By identifying the challenges and opportunities, this review provided insights into how healthcare providers, policymakers, and other stakeholders can work together to improve the availability and accessibility of immunotherapy to BC patients in Africa.

The CDK4/6 inhibitors biomarker landscape: The most relevant biomarkers of response or resistance for further research and potential clinical utility

Cyclin-Dependent Kinase 4/6 inhibitors (CDK4/6is) in combination with Endocrine Therapy (ET) represent the standard frontline therapy for patients with Hormone Receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic Breast Cancer (mBC). Clinical activity and efficacy of CDK4/6is-based therapies have been proven both in the endocrine sensitive and resistant settings. Therapy resistance eventually underpins clinical progression to any CDK4/6is-based therapies, yet there is a lack of validated molecular biomarkers predictive of either intrinsic or acquired resistance to CDK4/6is in clinical practice. As the "post-CDK4/6is" landscape for the management of HR-positive/HER2-negative mBC is rapidly evolving with the introduction of novel therapies, there is an urgent need for the definition of clinically relevant molecular biomarkers of intrinsic/acquired resistance mechanisms to CDK4/6is. This narrative review outlines the role of currently approved CDK4/6is-based therapies, describes the most relevant molecular biomarkers of CDK4/6is-resistance, and ultimately provides a perspective on the clinical and research scenario.

ESR1 mutations in HR+/HER2-metastatic breast cancer: Enhancing the accuracy of ctDNA testing

Activating mutations of the estrogen receptor alpha gene (ESR1) are common mechanisms of endocrine therapy (ET) resistance in hormone receptor-positive (HR + )/Human Epidermal Growth Factor Receptor 2 (HER2)-negative metastatic breast cancer (MBC). Recent clinical findings emphasize that both old and new generations of selective ER degraders (SERDs) demonstrate enhanced clinical effectiveness in patients with MBC who have detectable ESR1 mutations via liquid biopsy. This stands in contrast to individuals with MBC carrying these mutations and undergoing conventional endocrine monotherapies like aromatase inhibitors (AIs). Liquid biopsy, particularly the analysis of circulating tumor DNA (ctDNA), has emerged as a promising, minimally invasive alternative to conventional tissue-based testing for identifying ESR1 mutations. Within the context of the PADA-1 and EMERALD trials, distinct molecular methodologies and assays, specifically digital droplet PCR (ddPCR) and next-generation sequencing (NGS), have been employed to evaluate the mutational status of ESR1 within ctDNA. This manuscript critically examines the advantages and indications of various ctDNA testing methods on liquid biopsy for HR+/HER2-negative MBC. Specifically, we delve into the capabilities of ddPCR and NGS in identifying ESR1 mutations. Each methodology boasts unique strengths and limitations: ddPCR excels in its analytical sensitivity for pinpointing hotspot mutations, while NGS offers comprehensive coverage of the spectrum of ESR1 mutations. The significance of meticulous sample handling and timely analysis is emphasized, acknowledging the transient nature of cfDNA. Furthermore, we underscore the importance of detecting sub-clonal ESR1 mutations, as these variants can exert a pivotal influence on predicting both endocrine therapy resistance and responsiveness to SERDs. In essence, this work discusses the role of ctDNA analysis for detecting ESR1 mutations and their implications in tailoring effective therapeutic strategies for HR+/HER2- MBC.

GRPR-targeting radiotheranostics for breast cancer management

Breast Cancer (BC) is the most common cancer worldwide and, despite the advancements made toward early diagnosis and novel treatments, there is an urgent need to reduce its mortality. The Gastrin-Releasing Peptide Receptor (GRPR) is a promising target for the development of theranostic radioligands for luminal BC with positive estrogen receptor (ER) expression, because GRPR is expressed not only in primary lesions but also in lymph nodes and distant metastasis. In the last decades, several GRPR-targeting molecules have been evaluated both at preclinical and clinical level, however, most of the studies have been focused on prostate cancer (PC). Nonetheless, given the relevance of non-invasive diagnosis and potential treatment of BC through Peptide Receptor Radioligand Therapy (PRRT), this review aims at collecting the available preclinical and clinical data on GRPR-targeting radiopeptides for the imaging and therapy of BC, to better understand the current state-of-the-art and identify future perspectives and possible limitations to their clinical translation. In fact, since luminal-like tumors account for approximately 80% of all BC, many BC patients are likely to benefit from the development of GRPR-radiotheranostics.

Epidemiology trends and progress in breast cancer survival: earlier diagnosis, new therapeutics

PURPOSE OF REVIEW

In this review we will critically appraise the latest evidence on breast cancer (BC) survival trends and discuss how these may reflect breakthroughs in early diagnosis and treatment approaches. We will address the wide global inequalities in BC survival and review the ongoing initiatives aimed at improving cancer control worldwide.

RECENT FINDINGS

BC outcomes have improved in high-income countries during the last decades, following the implementation of strategies for early detection and optimal multimodality treatment. Novel therapeutics, such as anti-HER2 targeted treatments, have also contributed to the progress in BC survival. However, BC mortality is still high in low-income countries, due to the lack of optimal healthcare infrastructures. In the context of marked inequities in BC management across world regions, international collaborations such as the Global Breast Cancer Initiative and the Global Initiative for Cancer Registry Development work to foster capacity-building in developing countries, tackle the burden of BC and deliver the Sustainable Development Goals by 2030.

SUMMARY

Collection of robust, high-quality data from population-based cancer registries is crucial to drive and refine public health interventions. Population-based data are also the litmus paper to evaluate the real-world impact of clinical advances and monitor progress.

Nanoparticle-based materials in anticancer drug delivery: Current and future prospects

The past decade has witnessed a breakthrough in novel strategies to treat cancer. One of the most common cancer treatment modalities is chemotherapy which involves administering anti-cancer drugs to the body. However, these drugs can lead to undesirable side effects on healthy cells. To overcome this challenge and improve cancer cell targeting, many novel nanocarriers have been developed to deliver drugs directly to the cancerous cells and minimize effects on the healthy tissues. The majority of the research studies conclude that using drugs encapsulated in nanocarriers is a much safer and more effective alternative than delivering the drug alone in its free form. This review provides a summary of the types of nanocarriers mainly studied for cancer drug delivery, namely: liposomes, polymeric micelles, dendrimers, magnetic nanoparticles, mesoporous nanoparticles, gold nanoparticles, carbon nanotubes and quantum dots. In this review, the synthesis, applications, advantages, disadvantages, and previous studies of these nanomaterials are discussed in detail. Furthermore, the future opportunities and possible challenges of translating these materials into clinical applications are also reported.

Understanding breast cancer complexity to improve patient outcomes: The St Gallen International Consensus Conference for the Primary Therapy of Individuals with Early Breast Cancer 2023

The 18th St Gallen International Breast Cancer Conference held in March 2023, in Vienna, Austria, assessed significant new findings for local and systemic therapies for early breast cancer with a focus on the evaluation of multimodal treatment options. The emergence of more effective, innovative agents in both the preoperative (primary or neoadjuvant) and post-operative (adjuvant) settings has underscored the pivotal role of a multidisciplinary approach in treatment decision making, particularly when selecting systemic therapy for an individual patient. The importance of multidisciplinary discussions regarding the clinical benefits of interventions was explicitly emphasized by the consensus panel as an integral part of developing an optimal treatment plan with the 'right' degree of intensity and duration. The panelists focused on controversies surrounding the management of common ductal/no special type and lobular breast cancer histology, which account for the vast majority of breast tumors. The expert opinion of the panelists was based on interpretations of available data, as well as current practices in their professional environments, personal and socioeconomic factors affecting patients, and cognizant of varying reimbursement and accessibility constraints around the world. The panelists strongly advocated patient participation in well-designed clinical studies whenever feasible. With these considerations in mind, the St Gallen Consensus Conference aims to offer guidance to clinicians regarding appropriate treatments for early-stage breast cancer and assist in balancing the realistic trade-offs between treatment benefit and toxicity, enabling patients and clinicians to make well-informed choices through a shared decision-making process.

Validity of Using Pathological Response as a Surrogate for Overall Survival in Neoadjuvant Studies for Esophageal Cancer: A Systematic Review and Meta-analysis

BACKGROUND

Pathological response is a critical factor in predicting long-term survival of patients with esophageal cancer after preoperative therapy. However, the validity of using pathological response as a surrogate for overall survival (OS) for esophageal cancer has not yet been established. In this study, a literature-based meta-analysis was conducted to evaluate pathological response as a proxy endpoint for survival in esophageal cancer.

METHODS

Three databases were systematically searched to identify relevant studies investigating neoadjuvant treatment for esophageal cancer. The correlation between pathological complete response (pCR) and OS were assessed using a weighted multiple regression analysis at the trial level, and the coefficient of determination (R2) was calculated. The research design and histological subtypes were considered in the performance of subgroup analysis.

RESULTS

In this meta-analysis, a total of 40 trials, comprising 43 comparisons and 55,344 patients were qualified. The surrogacy between pCR and OS was moderate (R2 = 0.238 in direct comparison, R2 = 0.500 for pCR reciprocals, R2 = 0.541 in log settings). pCR could not serve as an ideal surrogate endpoint in randomized controlled trials (RCTs) (R2 = 0.511 in direct comparison, R2 = 0.460 for pCR reciprocals, R2 = 0.523 in log settings). A strong correlation was observed in studies comparing neoadjuvant chemoradiotherapy and neoadjuvant chemotherapy (R2 = 0.595 in direct comparison, R2 = 0.840 for pCR reciprocals, R2 = 0.800 in log settings).

CONCLUSIONS

A lack of surrogacy of pathological response for long-term survival at trial level is established in this study. Hence, caution should be exercised when using pCR as the primary endpoint in neoadjuvant studies for esophageal cancer.

ESR1 Gene Mutations and Liquid Biopsy in ER-Positive Breast Cancers: A Small Step Forward, a Giant Leap for Personalization of Endocrine Therapy?

The predominant forms of breast cancer (BC) are hormone receptor-positive (HR+) tumors characterized by the expression of estrogen receptors (ERs) and/or progesterone receptors (PRs). Patients with HR+ tumors can benefit from endocrine therapy (ET). Three types of ET are approved for the treatment of HR+ BCs and include selective ER modulators, aromatase inhibitors, and selective ER downregulators. ET is the mainstay of adjuvant treatment in the early setting and the backbone of the first-line treatment in an advanced setting; however, the emergence of acquired resistance can lead to cancer recurrence or progression. The mechanisms of ET resistance are often related to the occurrence of mutations in the ESR1 gene, which encodes the ER-alpha protein. As ESR1 mutations are hardly detectable at diagnosis but are present in 30% to 40% of advanced BC (ABC) after treatment, the timeline of testing is crucial. To manage this resistance, ESR1 testing has recently been recommended; in ER+ HER2- ABC and circulating cell-free DNA, so-called liquid biopsy appears to be the most convenient way to detect the emergence of ESR1 mutations. Technically, several options exist, including Next Generation Sequencing and ultra-sensitive PCR-based techniques. In this context, personalization of ET through the surveillance of ESR1 mutations in the plasma of HR+ BC patients throughout the disease course represents an innovative way to improve the standard of care.

Tailoring Potential Natural Compounds for the Treatment of Luminal Breast Cancer

Breast cancer (BC) is the most diagnosed cancer worldwide, mainly affecting the epithelial cells from the mammary glands. When it expresses the estrogen receptor (ER), the tumor is called luminal BC, which is eligible for endocrine therapy with hormone signaling blockade. Hormone therapy is essential for the survival of patients, but therapeutic resistance has been shown to be worrying, significantly compromising the prognosis. In this context, the need to explore new compounds emerges, especially compounds of plant origin, since they are biologically active and particularly promising. Natural products are being continuously screened for treating cancer due to their chemical diversity, reduced toxicity, lower side effects, and low price. This review summarizes natural compounds for the treatment of luminal BC, emphasizing the activities of these compounds in ER-positive cells. Moreover, their potential as an alternative to endocrine resistance is explored, opening new opportunities for the design of optimized therapies.

Proposing a novel molecular subtyping scheme for predicting distant recurrence-free survival in breast cancer post-neoadjuvant chemotherapy with close correlation to metabolism and senescence

Background

High relapse rates remain a clinical challenge in the management of breast cancer (BC), with distant recurrence being a major driver of patient deterioration. To optimize the surveillance regimen for distant recurrence after neoadjuvant chemotherapy (NAC), we conducted a comprehensive analysis using bioinformatics and machine learning approaches.

Materials and methods

Microarray data were retrieved from the GEO database, and differential expression analysis was performed with the R package 'Limma'. We used the Metascape tool for enrichment analyses, and 'WGCNA' was utilized to establish co-expression networks, selecting the soft threshold power with the 'pickSoftThreshold' algorithm. We integrated ten machine learning algorithms and 101 algorithm combinations to identify key genes associated with distant recurrence in BC. Unsupervised clustering was performed with the R package 'ConsensusCluster Plus'. To further screen the key gene signature of residual cancer burden (RCB), multiple knockdown studies were analyzed with the Genetic Perturbation Similarity Analysis (GPSA) database. Single-cell RNA sequencing (scRNA-seq) analysis was conducted through the Tumour Immune Single-cell Hub (TISCH) database, and the XSum algorithm was used to screen candidate small molecule drugs based on the Connectivity Map (CMAP) database. Molecular docking processes were conducted using Schrodinger software. GMT files containing gene sets associated with metabolism and senescence were obtained from GSEA MutSigDB database. The GSVA score for each gene set across diverse samples was computed using the ssGSEA function implemented in the GSVA package.

Results

Our analysis, which combined Limma, WGCNA, and machine learning approaches, identified 16 RCB-relevant gene signatures influencing distant recurrence-free survival (DRFS) in BC patients following NAC. We then screened GATA3 as the key gene signature of high RCB index using GPSA analysis. A novel molecular subtyping scheme was developed to divide patients into two clusters (C1 and C2) with different distant recurrence risks. This molecular subtyping scheme was found to be closely associated with tumor metabolism and cellular senescence. Patients in cluster C2 had a poorer DRFS than those in cluster C1 (HR: 4.04; 95% CI: 2.60-6.29; log-rank test p < 0.0001). High GATA3 expression, high levels of resting mast cell infiltration, and a high proportion of estrogen receptor (ER)-positive patients contributed to better DRFS in cluster C1. We established a nomogram based on the N stage, RCB class, and molecular subtyping. The ROC curve for 5-year DRFS showed excellent predictive value (AUC=0.91, 95% CI: 0.95-0.86), with a C-index of 0.85 (95% CI: 0.81-0.90). Entinostat was identified as a potential small molecule compound to reverse high RCB after NAC. We also provided a comprehensive review of the EDCs exposures that potentially impact the effectiveness of NAC among BC patients.

Conclusion

This study established a molecular classification scheme associated with tumor metabolism and cancer cell senescence to predict RCB and DRFS in BC patients after NAC. Furthermore, GATA3 was identified and validated as a key gene associated with BC recurrence.

Human basal-like breast cancer is represented by one of the two mammary tumor subtypes in dogs

BACKGROUND

About 20% of breast cancers in humans are basal-like, a subtype that is often triple-negative and difficult to treat. An effective translational model for basal-like breast cancer is currently lacking and urgently needed. To determine whether spontaneous mammary tumors in pet dogs could meet this need, we subtyped canine mammary tumors and evaluated the dog-human molecular homology at the subtype level.

METHODS

We subtyped 236 canine mammary tumors from 3 studies by applying various subtyping strategies on their RNA-seq data. We then performed PAM50 classification with canine tumors alone, as well as with canine tumors combined with human breast tumors. We identified feature genes for human BLBC and luminal A subtypes via machine learning and used these genes to repeat canine-alone and cross-species tumor classifications. We investigated differential gene expression, signature gene set enrichment, expression association, mutational landscape, and other features for dog-human subtype comparison.

RESULTS

Our independent genome-wide subtyping consistently identified two molecularly distinct subtypes among the canine tumors. One subtype is mostly basal-like and clusters with human BLBC in cross-species PAM50 and feature gene classifications, while the other subtype does not cluster with any human breast cancer subtype. Furthermore, the canine basal-like subtype recaptures key molecular features (e.g., cell cycle gene upregulation, TP53 mutation) and gene expression patterns that characterize human BLBC. It is enriched in histological subtypes that match human breast cancer, unlike the other canine subtype. However, about 33% of canine basal-like tumors are estrogen receptor negative (ER-) and progesterone receptor positive (PR+), which is rare in human breast cancer. Further analysis reveals that these ER-PR+ canine tumors harbor additional basal-like features, including upregulation of genes of interferon-γ response and of the Wnt-pluripotency pathway. Interestingly, we observed an association of PGR expression with gene silencing in all canine tumors and with the expression of T cell exhaustion markers (e.g., PDCD1) in ER-PR+ canine tumors.

CONCLUSIONS

We identify a canine mammary tumor subtype that molecularly resembles human BLBC overall and thus could serve as a vital translational model of this devastating breast cancer subtype. Our study also sheds light on the dog-human difference in the mammary tumor histology and the hormonal cycle.