Fulvestrant 500 milligrams as endocrine therapy for endocrine sensitive advanced breast cancer patients in the real world: the Ful500 prospective observational trial

Efficacy of Fulvestrant in Women with Hormone-Resistant Metastatic Breast Cancer (mBC): A Canadian Province Experience

Simple Summary

Fulvestrant is a medication that is approved as first and second-line treatment in patients with hormone receptor positive advanced breast cancer. In clinical practice, fulvestrant is still used beyond the second line of treatment. This study investigated the use of fulvestrant in a Saskatchewan population of women with advanced breast cancer. We found that fulvestrant is effective when used in both the early and later lines of treatment, although the benefit is more pronounced in the earlier line of therapy. Women with disease affecting their visceral organs such as lung, liver or peritoneum had decreased disease control and survival on fulvestrant. Women who had received chemotherapy after fulvestrant and had a clinical response to fulvestrant had better survival.

Abstract

Introduction: Fulvestrant has demonstrated efficacy in hormone receptor positive (HR+) metastatic breast cancer (mBC), both in first-and second-line settings. In clinical practice, however, fulvestrant has been used as a later-line therapy. This study assessed the efficacy of fulvestrant in women with mBC in early-versus later-line therapy. Methods: This retrospective cohort study assessed Saskatchewan women with HR+ mBC who received fulvestrant between 2003–2019. A multivariate Cox proportional survival analysis was performed. Results: One hundred and eighty-six women with a median age of 63.5 years were identified—178 (95.6%) had hormone-resistant mBC, 57.5% had visceral disease, and 43.0% had received chemotherapy before fulvestrant. 102 (54.8%) women received ≤2-line-therapy, and 84 (45.2%) received ≥3 line-therapy before fulvestrant. The median time to progression (TTP) was 12 months in the early-treatment vs. 6 months in the later-treatment group, p = 0.015. Overall survival (OS) from the start of fulvestrant was 26 months in the early-treatment group vs. 16 months in the later-treatment group, p = 0.067. On multivariate analysis, absence of visceral metastasis, HR: 0.70 (0.50–0.99), was significantly correlated with better TTP, whereas post-fulvestrant chemotherapy, HR: 0.32 (0.23–0.47), clinical benefit from fulvestrant, HR: 0.44 (0.30–0.65), and absence of visceral metastasis, HR: 0.70 (0.50–0.97), were correlated with better OS. Conclusions: Fulvestrant has demonstrated efficacy as both early-and later-line therapy in hormone-resistant mBC. Our results show that women with clinical benefit from fulvestrant, who received post-fulvestrant chemotherapy, or had non-visceral disease, had better survival.

Optimal duration of prior endocrine therapy predicts the efficacy of Fulvestrant in a real-world study for patients with hormone receptor-positive and HER2-negative advanced breast cancer

Fulvestrant 500 mg is standard of care for endocrine therapy-naive or pretreated women with hormone receptor-positive (HR+) metastatic breast cancer (MBC). This study was conducted to explore the potential factors and duration of last endocrine therapy as predictors for the efficacy of fulvestrant 500 mg on Chinese patients in real-world practice. Two hundred and fifty-two MBC patients who were treated with fulvestrant 500 mg consecutively between January 2011 and December 2015 in our institute were included in this study. Efficacy outcomes included progression-free survival (PFS), overall survival (OS), and clinical benefit rate (CBR). The optimal cut-off value for duration of last endocrine therapy was determined by survival ROC analysis. Adverse events were graded according to NCI-CTC AE 4.0. Fulvestrant 500 mg demonstrated a median PFS of 5.8 months (95%CI 4.6-6.9), and a median OS of 35.9 months (95%CI 30.2-41.4). CBR was 41.3% (95%CI 35-47). Liver metastasis, bone alone metastasis, lines of endocrine therapy for MBC, and sensitivity to last endocrine therapy were statistically significant in the Cox multivariate analysis (P values of 0.022, 0.02, 0.03, and 0.038, respectively). The optimal cut-off values for duration of last endocrine therapy to predict the efficacy of fulvestrant 500 mg were 25.08 months for adjuvant endocrine therapy and 5.17 months for first-line endocrine therapy, which showed no difference in prediction power with ABC clinical definition. Patients with prior adjuvant endocrine therapy ≥25.08 months or first-line therapy≥5.17 months reached a longer PFS of fulvestrant (p = 0.04). Six patients discontinued the treatment due to intolerable adverse events. Patients with the duration of prior endocrine therapy longer than optimal cut-off points indicate better PFS of fulvestrant. Liver metastasis, bone alone metastasis, line of fulvestrant, and sensitivity to last endocrine therapy were also predictors for response of fulvestrant. ClinicalTrials.gov Identifier: NCT03708432.

Prediction of fulvestrant efficacy in patients with advanced breast cancer: retrospective-prospective evaluation of the predictive potential of a multigene expression assay

BACKGROUND

Fulvestrant is a selective oestrogen receptor (ER) degrader used as monotherapy and combination therapy for ER positive HER2 negative advanced breast cancer (ABC) in postmenopausal women. The drug response predictor (DRP), is a mathematical algorithm based on the expression of multiple genes in the tumour. The fulvestrant DRP algorithm has previously shown effect in BC. In this study, we investigated the DRP's potential in predicting fulvestrant benefit.

METHOD

Among 695 patients with ABC prospectively included in a Danish Breast Cancer Cooperative Group (DBCG) cohort we retrospectively included 226 patients who received fulvestrant as monotherapy. The DRP result was based on mRNA extracted from tumour biopsies and analysed using Affymetrix array. Primary endpoint was time to progression (TTP).

RESULTS

For patients who received fulvestrant in line one to four and were previously unexposed to adjuvant endocrine therapy, we identified a hazard ratio (HR) of 0.44 (90% confidence interval (90% CI) upper limit of 1.08, one sided p = 0.066) for a predicted positive vs negative outcome. A weaker association was seen when including patients exposed to adjuvant endocrine treatment or received fulvestrant in fifth or later lines. Exploratory analyses showed that the DRP was efficient when using recent biopsies for DRP estimate and among recently treated patients.

CONCLUSION

The DRP showed a potential in predicting fulvestrant treatment but was not significant in the overall analysis. Use of older biopsies, long-term endocrine treatment and multiple therapies between biopsy used for analysis and fulvestrant treatment, probably affect the predictive accuracy.

Multicenter Observational Study of Fulvestrant 500 mg in Postmenopausal Japanese Women with Estrogen Receptor-Positive Advanced or Recurrent Breast Cancer after Prior Endocrine Treatment (SBCCSG29 Study)

BACKGROUND

Fulvestrant 500 mg has been an option for endocrine therapy for advanced or recurrent breast cancer after prior endocrine treatment since November 2011 in Japan. This study aimed to clarify the effectiveness and safety of fulvestrant 500 mg in clinical settings.

METHODS

This was a multicenter, both prospective and retrospective, observational study of 132 postmenopausal women (median age 66) with locally advanced or metastatic breast cancer, who had been treated with fulvestrant. Information from medical records was retrospectively obtained from 9 hospitals (Saitama Breast Cancer Clinical Study Group: SBCCSG) in Saitama prefecture, Japan, from October 2012 to April 2014. The primary end point was time to treatment failure (TTF). The secondary end points were overall survival (OS), objective response rate (ORR), clinical benefit rate (CBR), and adverse events (AE) (CTCAE ver. 4). The choice of subsequent therapy after fulvestrant was also evaluated.

RESULTS

The median TTF was 6.1 months. Median OS was 28.5 months (the starting date was the first day of fulvestrant). ORR was 12.9% and CBR was 45.5%. The most common AEs were injection site reactions (9.1%). The rate of grade 3 AE was only 2.3% (3/132). The number of patients who underwent subsequent therapy after fulvestrant were 54 (55.7%) receiving chemotherapy, 42 (43.3%) receiving non-fulvestrant endocrine therapy, and 1 (1%) receiving mammalian target of rapamycin inhibitor (mTORi) + endocrine therapy (ET).

CONCLUSION

Fulvestrant 500 mg is an effective and safe treatment for patients with advanced or recurrent breast cancer after prior endocrine treatment.

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

Background:

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

Patients and methods:

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

Results:

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

Conclusions:

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

Treatment after Progression on Fulvestrant among Metastatic Breast Cancer Patients in Clinical Practice: a Multicenter, Retrospective Study

Fulvestrant (Ful) is an effective and widely used agent for first- and second-line treatment of hormone receptor-positive, human epidermal growth factor receptor-2-negative (HR+/HER2-) metastatic breast cancer (MBC). However, there is no evidence of treatment after progression on Ful. Our study aimed to investigate the profile of daily practice regarding therapy after Ful. A consecutive series of 131 HR+, HER2- MBC patients who failed Ful 500 mg as first-line or second-line therapy from June 2014 to June 2017 in 6 institutions were included and analysed. Among 131 patients who failed Ful with similar baseline characteristics, 31 (23.7%) received endocrine therapy (ET), and 100 (76.3%) were treated with chemotherapy (CT). The most frequently applied CT regimen was capecitabine (32%), and the ET regimen was exemestane + everolimus (35.5%). Multivariate analysis showed that patients with bone-only metastasis were associated with lower CT use (OR = 7.97, 95% CI 1.51-41.84, P = 0.01). Among patients who received CT and ET as subsequent treatments, the median progression-free survival (PFS) was 7.5 months (95% CI 6.2-8.8) and 6.0 months (95% CI 4.1-7.9), respectively (p = 0.03). Among patients who were resistant to Ful (PFS < 6 months), the PFS on CT was significantly longer than that on ET (7.1 months vs 3.9 months, p = 0.024, HR = 0.5, 95% CI 0.26-0.97); however, among patients with a PFS ≥6 months on Ful, the efficacy of CT and ET was similar. Additionally, among patients with an older age, bone-only metastasis and ≥3 metastatic sites, no significant difference was observed between the CT and ET groups. Moreover, ET was much more tolerated than CT in terms of the incidence of grade 3/4 toxicities (9.6% vs 27%, P < 0.05). Median overall survival (OS) was not reached. Thus, our findings reveal the pattern of post-Ful treatment in current clinical practice and provide evidence on the efficacy, safety and choice of these treatments.

Metastases to extraocular muscles from breast cancer: case report and up-to-date review of the literature

Background

Unilateral or bilateral metastases to extraocular muscles are very rare in breast cancer.

Case presentation

We describe a case of inferior rectus extraocular muscle involved by ductal luminal B/Her-2 neu negative breast cancer, observed in a cohort of 580 patients. Our patient had received chemotherapy and hormonal therapy (tamoxifen for 3 years and letrozole in the following 3 years) for her primary cancer and developed an orbital metastasis while she was under aromatase inhibitor-based therapy. Diagnosis was confirmed by MRI and biopsy. Orbital radiotherapy, combined with fulvestrant, resulted in shrinking of the secondary mass. A third line hormonal therapy using palbociclib was then started. Twelve-months later, MRI showed no residual tumor mass. Currently, the patient is alive and in good general conditions after 20 months.

Conclusions

Literature review yielded 57 patients with extraocular muscle metastases from breast cancer, mostly due to the invasive lobular subtype of carcinoma. In addition to the present case, only 4 other extraocular muscles metastases from invasive ductal carcinoma has been reported, pointing out to the rarity of ductal type spread to the orbit in the natural history of breast cancer. Surgery may be used as a single treatment, despite no improvement of symptoms. Radiotherapy alone or combined with chemotherapy, or with chemotherapy plus hormonal therapy are available options. Results are, however, missing or poor. The present case is the first one with complete and stable response after 20 months to radiotherapy, antiestrogen drug fulvestrant and selective inhibitor of CDK4 /CDK6 palbociclib. In this subset of patients, with unusual metastatic sites and frequent multi-organ metastatic impairment, a multidisciplinary approach is indicated in order to achieve the best therapeutic management and long-term surveillance.

Endoxifen, 4-Hydroxytamoxifen and an Estrogenic Derivative Modulate Estrogen Receptor Complex Mediated Apoptosis in Breast Cancer

Estrogen therapy was used to treat advanced breast cancer in postmenopausal women for decades until the introduction of tamoxifen. Resistance to long-term estrogen deprivation (LTED) with tamoxifen and aromatase inhibitors used as a treatment of breast cancer inevitably occurs, but unexpectedly low-dose estrogen can cause regression of breast cancer and increase disease-free survival in some patients. This therapeutic effect is attributed to estrogen-induced apoptosis in LTED breast cancer. Here, we describe modulation of the estrogen receptor (ER) liganded with antiestrogens (endoxifen and 4-hydroxytamoxifen) and an estrogenic triphenylethylene (TPE), ethoxytriphenylethylene (EtOXTPE), on estrogen-induced apoptosis in LTED breast cancer cells. Our results show that the angular TPE estrogen (EtOXTPE) is able to induce the ER-mediated apoptosis only at a later time compared with planar estradiol in these cells. Using real-time polymerase chain reaction, chromatin immunoprecipitation, western blotting, molecular modeling, and X-ray crystallography techniques, we report novel conformations of the ER complex with an angular estrogen EtOXTPE and endoxifen. We propose that alteration of the conformation of the ER complexes, with changes in coactivator binding, governs estrogen-induced apoptosis through the protein kinase regulated by RNA-like endoplasmic reticulum kinase sensor system to trigger an unfolded protein response.

Chemotherapeutic agents for the treatment of metastatic breast cancer: An update

Breast cancer is the second greatest cause of death among women worldwide; it comprises a group of heterogeneous diseases that evolves due to uncontrolled cellular growth and differentiation and the loss of normal programmed cell death. There are different molecular sub-types of breast cancer; therefore, various options are selected for treatment of different forms of metastatic breast cancer. However, the use of chemotherapeutic drugs is usually accompanied by deleterious side effects and the development of drug resistance when applied for a longer period. This review offers a classification of these chemotherapeutic agents according to their modes of action and therefore improves the understanding of molecular targets that are affected during treatment. Overall, it will allow the clinician to identify more specific targets to increase the effectiveness of a drug and to reduce general toxicity, resistance and other side effects.