Treatment Experience of Early-Stage Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer in a Real-World Setting: European Patients’ Perspectives

Cyclin-dependent kinase 4/6 inhibitors, which act by inhibiting progression from the G1 to S phases of the cell cycle, include palbociclib, ribociclib, abemaciclib, and trilaciclib. Palbociclib and ribociclib are currently food and drug administration-approved for use in combination with aromatase inhibitors in postmenopausal women with metastatic hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer. Palbociclib is also food and drug administration-approved for use in combination with fulvestrant in hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer progressing after endocrine therapy. Abemaciclib is the newest cyclin-dependent kinase 4/6 inhibitor to gain Food and Drug Administration (FDA) approval, specifically as monotherapy for hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer previously treated with chemotherapy and endocrine therapy. Abemaciclib also shares a similar indication with palbociclib for use in combination with fulvestrant in hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer progressing after endocrine therapy. Trilaciclib use remains largely investigational at this time. However, despite FDA-approval for only metastatic hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer, all four cyclin-dependent kinase 4/6 inhibitors have shown promise in hematologic malignancies and non-breast solid tumors. Although further research is needed, cyclin-dependent kinase 4/6 inhibitors represent intriguing developments in the treatment of various malignancies, including those with such poor prognoses as glioblastoma multiforme, mantle cell lymphoma, and metastatic melanoma. We discuss the approved indications, current research, and areas of future exploration for palbociclib, ribociclib, abemaciclib, and trilaciclib.

Estradiol is a key factor for tumorigenesis and prognosis of hormone receptor-positive breast cancer. Adipocytes are one source of estradiol in patients with breast cancer. Recent studies have shown that phosphorylated ribosomal protein S6 kinase-1 plays a critical role in adipogenesis. Therefore, estrogen depletion therapy might have beneficial effects in phosphorylated ribosomal protein S6 kinase-1-positive breast cancer. This study was conducted to evaluate the value of phosphorylated ribosomal protein S6 kinase-1 as a marker for gonadotropin-releasing hormone agonist treatment, a form of estrogen depletion therapy, for premenopausal patients with HR-positive, human epidermal growth factor receptor 2-negative breast cancer. We reviewed the medical records of 296 premenopausal patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative primary invasive breast cancer treated between 2008 and 2015. Phosphorylated ribosomal protein S6 kinase-1 positivity was defined by immunohistochemical staining scores of 1+, 2+ and 3+, whereas a score of 0 was considered negative. Phosphorylated ribosomal protein S6 kinase-1-positive tumors were found in 74.0% of the patients. In the phosphorylated ribosomal protein S6 kinase-1-positive group, disease-free survival of patients treated with a gonadotropin-releasing hormone agonist was significantly longer than that of patients treated without a gonadotropin-releasing hormone agonist (mean 106.7 months vs mean 91.1 months, P = 0.018). Phosphorylated ribosomal protein S6 kinase-1 is a potential biomarker for predicting the efficacy of gonadotropin-releasing hormone agonist therapy in premenopausal patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer.

Introduction: This systematic literature review sought to determine the concordance of PIK3CA mutations in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC) patients. Methods: A comprehensive search of PubMed/MEDLINE, EMBASE, Cochrane Central, and select conference abstracts was performed by two independent researchers that included, but was not limited to, keywords: “breast neoplasm,” “PIK3CA protein,” “hormone receptor positive,” and “metastases.” Databases were searched for English-language publications in HR+, HER2- mBC published between January 1993 through August 2017. Studies were included if results reported were specific to patients with HR+, HER2- mBC and reported data comparing PIK3CA mutations from liquid biopsies versus tumor biopsies or primary tumor samples versus metastatic lesion samples. Concordance was assessed between tissue samples (mutations found in primary tumors versus those from metastatic lesions) and between biopsy methods (i.e., tumor biopsy versus liquid biopsy) when the assessment was done at a variety of time points including time of initial diagnosis and time of diagnosis at disease progression. Content analysis was employed to quantify collected data elements. Results: Of 558 studies included for full-text review, four met inclusion criteria (number of patient samples [n]=358). One study (n = 9) found the concordance between the mutation status of primary breast tumors to the mutation status of metastatic lesions to be 100%. Three studies (n = 47; n = 55; n = 247) determined the concordance of PIK3CA mutations between tumor biopsies and liquid biopsies with concordance ranging from 70.4% to 94%. One study found that the concordance of circulating tumor DNA (ctDNA) against tumor biopsy was higher among metastatic lesions only (81.6%) relative to using all tumor samples (either primary or metastatic lesions) (70.4%). Conclusions: Available evidence suggested high level of concordance across sampling methods as well as across time. However, additional evidence is needed to increase study generalizability as well as to assess other possible confounding factors, such as differential timing between tumor and liquid biopsies. Citation Format: Alejandra Aguilar, Joni Dean, Elizabeth Anderson, Lea Mollon, Lisa Davis, Terri Warholak, Ayal Aizer, Emma Platt, Aditya Bardiya, Derek Tang. Concordance of PIK3CA mutations in hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer: A systematic literature review [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2217.

Conditional progression-free survival in patients with metastatic hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer treated with first-line ribociclib and endocrine therapy: real-world data from the RIBANNA study.

Quality-Assured Analysis of PIK3CA Mutations in Hormone Receptor–Positive/Human Epidermal Growth Factor Receptor 2–Negative Breast Cancer Tissue

Dysregulation of the cyclin D-CDK4/6-INK4-RB pathway, which leads to uncontrolled cell proliferation, is frequently observed in breast cancer. Recently, 3 CDK4/6 inhibitors have been FDA approved as first-line treatment for patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer. Despite promising clinical results, the metabolic response to treatment with these new drugs has not been elaborately demonstrated yet. Herein, we presented a patient with hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer who demonstrated a complete metabolic response on 18F-FDG PET/CT to treatment with a CDK4/6 inhibitor (ribociclib).

The addition of palbociclib (a cyclin-dependent kinase 4/6 inhibitor) to endocrine therapy (ET) has been shown to significantly improve progression-free survival (PFS) and overall survival (OS) among patients with hormone receptor-positive (HR+) advanced breast cancer. The current study presents the local experience of using palbociclib at two cancer centers in Saudi Arabia. Electronic data of patients with metastatic HR+ and human epidermal growth factor receptor 2-negative breast cancer who progressed after prior ET and received at least one cycle of palbociclib plus ET, were retrospectively reviewed. A total of 97 patients were identified, and their data were included in the analysis. The median age of the patients was 55 years. Patients were heavily pretreated in the metastatic setting (55% received systemic chemotherapy and 49% received two or more lines of prior ET). In total, 29 (30%) and 50 (52%) patients achieved an objective response and clinical benefit, respectively. The median follow-up time was 31.0 months [95% confidence interval (CI), 16.9-44.9] and the median PFS time was 16.3 months (95% CI, 11.4-21.2), with 58% of patients remaining progression-free at 12 months. Upon multivariate regression analysis, liver involvement was the only significant independent variable that predicted a greater risk of progression or death (hazard ratio, 2.32; 95% CI, 1.22-4.40; P=0.010). The median OS time was 19.6 months (95% CI, 18.1-20.9), with 12- and 24-month OS rates of 75 and 30%, respectively. Overall, real-world data showed that administration of palbociclib in combination with ET in patients with advanced HR+ breast cancer achieved a favorable outcome that was comparable to that reported in clinical trials.

BackgroundThis was a Japanese subpopulation analysis of MONARCH 2, a double-blind, randomized, placebo-controlled, phase 3 study of abemaciclib plus fulvestrant in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer (ABC).MethodsEligible women had progressed on (neo)adjuvant endocrine therapy (ET), ≤ 12 months from end of adjuvant ET, or on first-line ET for ABC, and had not received chemotherapy for ABC. Patients were randomized 2:1 to receive abemaciclib or placebo plus fulvestrant. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), pharmacokinetics (PK), health-related quality of life (HRQoL), and safety.ResultsIn Japan, 95 patients were randomized (abemaciclib, n = 64; placebo, n = 31). At final PFS analysis (February 14, 2017), median PFS was 21.2 and 14.3 months, respectively, in the abemaciclib and placebo groups (hazard ratio: 0.672; 95% confidence interval: 0.380–1.189). Abemaciclib had a higher objective response rate (37.5%) than placebo (12.9%). PK and safety profiles for Japanese patients were consistent with those of the overall population, without clinically meaningful differences across most HRQoL dimensions evaluated. The most frequent adverse events in the abemaciclib versus placebo groups were diarrhea (95.2 versus 25.8%), neutropenia (79.4 versus 0%), and leukopenia (66.7 versus 0%). At a second data cutoff (June 20, 2019), median OS was not reached with abemaciclib and 47.3 months with placebo (hazard ratio: 0.755; 95% confidence interval: 0.390–1.463).ConclusionsResults of the Japanese subpopulation were consistent with the improved clinical outcomes and manageable safety profile observed in the overall population.Clinical trial registrationNCT02107703; U.S. National Library of Medicine: https://clinicaltrials.gov/ct2/show/NCT02107703.

Simple SummaryHormone therapy for breast cancer targets estrogen receptors to inhibit the growth of cancer cells. We previously reported that neural precursor cell-expressed developmentally downregulated 4–1 (NEDD4) promotes the degradation of the estrogen receptor α. Therefore, NEDD4 may affect the efficacy of hormone therapy and prognosis in hormone receptor-positive breast cancer patients. The prognosis of patients receiving perioperative neoadjuvant or adjuvant hormone therapy for 5–10 years could be particularly affected by NEDD4. This study revealed that patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer with low NEDD4 expression had a good outcome. Additionally, the association of NEDD4 with estrogen receptor α in breast cancer cells was also investigated to reveal the biological mechanisms that influenced clinical results. NEDD4 expression appears to be a predictive factor of the response to hormone therapy.Neural precursor cell-expressed developmentally downregulated 4–1 (NEDD4) is an E3 ligase that leads to the degradation of proteins, including estrogen receptor α. We evaluated whether the expression level of NEDD4 affected the outcome of breast cancer patients. We performed a retrospective cohort study enrolling 143 patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer. Of the 66 patients with high NEDD4 mRNA levels (high NEDD4 group) and 77 patients with low NEDD4 mRNA levels (low NEDD4 group), 98.4% and 96.1%, respectively, of the patients had received neoadjuvant/adjuvant hormone therapy. Disease-free survival and overall survival were significantly longer in the low NEDD4 group than in the high NEDD4 group (p = 0.048 and p = 0.022, respectively). Western blotting revealed a high expression of estrogen receptor α in the NEDD4-knockdown culture cells. The proliferation of NEDD4-knockdown cells treated with tamoxifen or estradiol deprivation was suppressed, compared with that of NEDD4-expressing cells. Knockdown of NEDD4 in breast cancer cells induced the accumulation of estrogen receptor α and increased sensitivity to hormone therapy. In summary, this mechanism may lead to a better prognosis in hormone receptor-positive breast cancer patients with a low expression of NEDD4.

Male breast cancer, comprising approximately 1% of all breast cancer cases, often leads to the exclusion of male patients as a criterion in clinical trials. While the efficacy of Cyclin-dependent kinases 4 and 6 (CDK 4/6) inhibitors has been established in metastatic hormone receptor-positive (HR +) and human epidermal growth factor receptor 2-negative (HER2 -) breast cancer in women, limited data exist on their effectiveness in male patients. We aimed to evaluate the efficacy and safety of palbociclib or ribociclib in male patients with breast cancer. This study is a multicenter, retrospective study. We included male patients with HR + and HER2-metastatic breast cancer who received palbociclib or ribociclib as first-line treatment. Our primary endpoints were progression-free survival (PFS), overall response rates (ORR), and drug-related adverse effects. A total of 46 male patients from 27 institutions were enrolled. The median age at initiation of CDK 4/6 inhibitors was 63.64 ± 13.69years, with a median follow-up of 21.33 (95% CI 14.92-27.74) months. The ORR were 84% for palbociclib and 76.2% for ribociclib. The mPFS for the entire cohort was 28.06months (95% CI 18.70-37.42). No significant difference in PFS was observed between palbociclib and ribociclib (mPFS: 24.46months (95% CI 11.51-37.42) vs 28.33months (95% CI 14.77-41.88), respectively, p = 0.211). No new adverse events were reported. This study demonstrates that palbociclib and ribociclib are effective and safe options for first-line treatment in male patients with HR + /HER2 - metastatic breast cancer. However, further prospective studies are warranted to establish their efficacy in this population.

Breast cryoablation for palliative and curative treatment of breast cancer has been performed for decades. Although there is a recent resurgence of interest in breast cryoablation with curative intent for...

Tucidinostat, which is a subtype-selective histone deacetylase inhibitor, has been approved in China for the treatment of hormone receptor-positive (HR+) human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC). However, existing evidence mainly stemmed from randomized controlled trials, and might have limitations in representing the complexities of clinical practice and diverse patient populations. Therefore, there is a need to explore the efficacy and optimal therapeutic modality for tucidinostat in real-world clinical settings. The objective of this real-world study was to analyze the clinical data of 47 patients with HR+/HER2- ABC who received tucidinostat treatment at West China Hospital, Sichuan University, between August 2020 and May 2023. The primary outcomes were progression-free survival (PFS) and clinical benefit rate [CBR; defined as partial response (PR) and stable disease (SD) for ≥6 months on clinical evaluation]. A total of 47 patients were included, and the median follow-up time was 18.20 months. The median line of tucidinostat therapy was 3 (range, 1-9). In all, 52.17% patients were treated with tucidinostat plus fulvestrant, while 38.30% were treated with tucidinostat plus aromatase inhibitors. Notably, 10.64% of the patients with rapidly progressing visceral metastases received tucidinostat plus endocrine therapy as maintenance treatment after achieving disease control with chemotherapy. The median PFS was 4.43 months [95% confidence interval (CI), 2.77-10.53], and the median overall survival was 19.57 months (95% CI, 12.83-not reached). The 6-month CBR for the overall population was 41.86%. Patients undergoing maintenance therapy demonstrated a significantly longer PFS than did those who did not receive it as maintenance therapy (14.13 vs. 3.93 months; P=0.01). Univariate Cox regression analysis showed that use of tucidinostat in lines 1-2, use of tucidinostat plus fulvestrant, presence of one metastatic site, and lack of brain metastasis were favorable factors for PFS. Thrombocytopenia was the most frequently reported adverse event, with an incidence rate of 31.91% at all grades and 14.89% at grade ≥3. Four (8.51%) patients discontinued the treatment. For patients with HR+/HER2- ABC, tucidinostat combination therapy offers certain survival benefits with controllable safety. Furthermore, compared with non-maintenance therapy, maintenance therapy after chemotherapy may have promising efficacy.

Long-term survival varies among hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer patients and is seriously impaired by metastasis. Chromosomal instability (CIN) was one of the key drivers of breast cancer metastasis. Here we evaluate CIN and 10-year invasive disease-free survival (iDFS) and overall survival (OS) in HR+/HER2-- breast cancer. In this large-scale, multiple-site, retrospective study, 354 HR+/HER2- breast cancer patients were recruited. Of these, 204 patients were used for internal training, 70 for external validation, and 80 for cross-validation. All medical records were carefully reviewed to obtain the disease recurrence information. Formalin-fixed paraffin-embedded tissue samples were collected, followed by low-pass whole-genome sequencing with a median genome coverage of 1.86X using minimal 1 ng DNA input. CIN was then assessed using a customized bioinformatics workflow. Three or more instances of CIN per sample was defined as high CIN and the frequency was 42.2% (86/204) in the internal cohort. High CIN correlated significantly with increased lymph node metastasis, vascular invasion, progesterone receptor negative status, HER2 low, worse pathological type, and performed as an independent prognostic factor for HR+/- breast cancer. Patients with high CIN had shorter iDFS and OS than those with low CIN [10-year iDFS 11.1% versus 82.2%, hazard ratio (HR) = 11.12, p < 0.01; 10-year OS 45.7% versus 94.3%, HR = 14.17, p < 0.01]. These findings were validated in two external cohorts with 70 breast cancer patients. Moreover, high CIN could predict the prognosis more accurately than Adjuvant! Online score (10-year iDFS 11.1% versus 48.6%, HR = 2.71, p < 0.01). Cross-validation analysis found that high consistency (83.8%) was observed between CIN and MammaPrint score, while only 45% between CIN and Adjuvant! Online score. In conclusion, high CIN is an independent prognostic indicator for HR+/HER2- breast cancer with shorter iDFS and OS and holds promise for predicting recurrence and metastasis.

To evaluate the clinical characteristics, pathological response, and prognostic significance of hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer (BC) after neoadjuvant chemotherapy (NAC). A survival analysis was performed to detect the factors related to recurrence and death in 3070 consecutive patients with HR+/HER2- BC who received NAC from 2011 to 2022. All patients received current "standard of care" following neoadjuvant therapy based on guidelines, including surgery and adjuvant endocrine therapy. HER2-low was defined as immunohistochemistry (IHC) 1+ or IHC 2+ and fluorescence in-situ hybridization-negative. The complete pathological response (pCR) (ypT0/is ypN0) rate was 14.5%. The clinical tumor size (cT), ER scores, PR status, and Ki67 levels were related to pCR. The 5-year disease-free survival (DFS) and overall survival (OS) rates were 82.6% and 90.4%, respectively. PR, Ki67 levels, and postmastectomy radiotherapy were independent factors for DFS and OS, and the extranodal extension (ENE) correlated with DFS. However, pCR and HER2 status were related to OS. The pCR rate in PR negativity BC was significantly higher than that in PR positivity BC (21.1% vs. 12.2%, p = 0.000), but PR negativity BC had a poorer prognosis than PR positivity BC. HER2-low BC showed high ER scores (over 50%), PR positivity, large ypT, ENE, and lymphovascular invasion but a lower pCR rate than HER2-zero BC. Patients with HER2-low BC had shorter OS than those with HER2-zero BC (p = 0.037). However, there was no difference in DFS. Depending on PR status and HER2 status, patients with ER positivity and HER2 negativity exhibit different pathologic complete response rates to neoadjuvant chemotherapy and long-term outcomes, especially patients with PR negativity or HER2-low status.

Neoadjuvant chidamide combined with chemotherapy in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer (MUKDEN 05): a multicentre, single-arm, phase 2 trial