Safety results from a phase III study (TURANDOT trial by CECOG) of first-line bevacizumab in combination with capecitabine or paclitaxel for HER-2-negative locally recurrent or metastatic breast cancer

Eribulin combined with antiangiogenic agents in women with HER2-negative metastatic breast cancer: a retrospective multicenter study

Background

The relative lack of specifically targeted agents for HER2-negative metastatic breast cancer (MBC) makes the need for new agents or combination therapies to maximize clinical benefit while reducing toxicity critical.

Objectives

To retrospectively analyze the efficacy and safety of eribulin combined with antiangiogenic drugs in the treatment of Chinese women with HER2-negative MBC.

Methods

A total of 85 consecutive MBC patients with HER2-negative who were treated with eribulin + antiangiogenic agents between October 2020 and April 2023 in four institutions were retrospectively included in this study. Patients received eribulin 1.4 mg/m2 (day 1 and 8) plus bevacizumab 7.5 mg/kg (day 1, 64 patients) or anlotinib 10 mg daily (day 1-14, 16 patients) or apatinib 250 mg daily (5 patients) on a 21-day cycle until progression or unacceptable toxicity. The primary end-point was progression-free survival (PFS), according to Response Evaluation Criteria in Solid tumors (RECIST) 1.1. Secondary end-points included toxicities, objective response rate (ORR), disease control rate (DCR), and overall survival (OS). Adverse events (AEs) were graded according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

Results

The study included 85 HER2-negative MBC patients, with 41 patients (48.2%) in the first to second line group and 44 patients (51.8%) in the greater than or equal to third line group. The median age was 54.0 years. Thirty patients in the first to second line group and 14 patients in the greater than or equal to third line group had triple-negative breast cancer (TNBC). The ORR and DCR were 34.1% (29/85) and 75.3% (64/85). The median PFS (mPFS) of total population was 6.0 months (95% CI: 4.3-7.7), and median OS (mOS) was immature. The mPFS was 7.7 and 4.3 months in the first to second and greater than or equal to third line treatment (p = 0.003), respectively. TNBC patients in first to second line therapy showed a significantly longer PFS (6.5 months versus 2.0 months, p = 0.021) compared to greater than or equal to third line. The incidences of cardiovascular toxicity were 29.4% in grades 1-2 and no grades 3-4. Hematologic toxicity (leukopenia and neutropenia) was the most common grade ⩾3 AEs, and AEs were more common in patients in greater than or equal to third line.

Conclusion

The results suggest that eribulin combined with antiangiogenic therapy has a meaningful clinical activity and an acceptable safety profile in HER2-negative MBC.

Redefining the Incidence and Profile of Fluoropyrimidine-Associated Cardiotoxicity in Cancer Patients: A Systematic Review and Meta-Analysis

Aim: The cardiac toxicity that occurs during administration of anti-tumor agents has attracted increasing concern. Fluoropyrimidines have been used for more than half a century, but their cardiotoxicity has not been well clarified. In this study, we aimed to assess the incidence and profile of fluoropyrimidine-associated cardiotoxicity (FAC) comprehensively based on literature data. Methods: A systematic literature search was performed using PubMed, Embase, Medline, Web of Science, and Cochrane library databases and clinical trials on studies investigating FAC. The main outcome was a pooled incidence of FAC, and the secondary outcome was specific treatment-related cardiac AEs. Random or fixed effects modeling was used for pooled meta-analyses according to the heterogeneity assessment. PROSPERO registration number: (CRD42021282155). Results: A total of 211 studies involving 63,186 patients were included, covering 31 countries or regions in the world. The pooled incidence of FAC, by meta-analytic, was 5.04% for all grades and 1.5% for grade 3 or higher. A total of 0.29% of patients died due to severe cardiotoxicities. More than 38 cardiac AEs were identified, with cardiac ischemia (2.24%) and arrhythmia (1.85%) being the most frequent. We further performed the subgroup analyses and meta-regression to explore the source of heterogeneity, and compare the cardiotoxicity among different study-level characteristics, finding that the incidence of FAC varied significantly among different publication decades, country/regions, and genders. Patients with esophagus cancer had the highest risk of FAC (10.53%), while breast cancer patients had the lowest (3.66%). The treatment attribute, regimen, and dosage were significantly related to FAC. When compared with chemotherapeutic drugs or targeted agents, such a risk was remarkably increased (χ2 = 10.15, p < 0.01; χ2 = 10.77, p < 0.01). The continuous 5-FU infusion for 3–5 consecutive days with a high dosage produced the highest FAC incidence (7.3%) compared with other low-dose administration patterns. Conclusions: Our study provides comprehensive global data on the incidence and profile of FAC. Different cancer types and treatment appear to have varying cardiotoxicities. Combination therapy, high cumulative dose, addition of anthracyclines, and pre-existing heart disease potentially increase the risk of FAC.

Venous Thromboembolism in Cancer Patients Undergoing Chemotherapy: A Systematic Review and Meta-Analysis

Objective: Venous thromboembolism (VTE) is a life-threatening complication that may exacerbate cancer prognosis. Whilst some studies indicate an increased risk of VTE in cancer patients undergoing chemotherapy, the prevalence estimates on the pooled prevalence of VTE in cancer patients undergoing chemotherapy are not known. This study aims to calculate the pooled prevalence of VTE in chemotherapy-treated cancer patients. Methods: Studies on VTE occurrence in cancer patients undergoing chemotherapy were retrieved after database search. The terms used included “cancer”, “chemotherapy”, and “venous thromboembolism”. A random-effects meta-analysis was conducted to obtain a pooled estimate of VTE prevalence in cancer patients undergoing chemotherapy. Results: A total of 102 eligible studies involving 30,671 patients (1773 with VTE, 28,898 without) were included in the meta-analysis. The pooled estimate of VTE prevalence was found to be 6%, ranging from 6% to 7% (ES 6%; 95% CI 6−7%; z = 18.53; p < 0.001). Conclusions: The estimated pooled prevalence rate of VTEs was 6% in cancer patients undergoing CRT, which was higher than the overall crude prevalence rate (5.78%). Comprehensive cancer care should consider stratified VTE risk assessment based on cancer phenotype, given that certain phenotypes of cancer such as bladder, gastric and ovarian posing particularly high risks of VTE.

Capecitabine for hormone receptor-positive versus hormone receptor-negative breast cancer

BACKGROUND

Retrospective analyses suggest that capecitabine may carry superior activity in hormone receptor-positive relative to hormone receptor-negative metastatic breast cancer. This review examined the veracity of that finding and explored whether this differential activity extends to early breast cancer.

OBJECTIVES

To assess effects of chemotherapy regimens containing capecitabine compared with regimens not containing capecitabine for women with hormone receptor-positive versus hormone receptor-negative breast cancer across the three major treatment scenarios: neoadjuvant, adjuvant, metastatic.

SEARCH METHODS

On 4 June 2019, we searched the Cochrane Breast Cancer Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 5) in the Cochrane Library; MEDLINE; Embase; the World Health Organization International Clinical Trials Registry Platform; and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials looking at chemotherapy regimens containing capecitabine alone or in combination with other agents versus a control or similar regimen without capecitabine for treatment of breast cancer at any stage. The primary outcome measure for metastatic and adjuvant trials was overall survival (OS), and for neoadjuvant studies pathological complete response (pCR).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias and certainty of evidence using the GRADE approach. Hazard ratios (HRs) were derived for time-to-event outcomes, and odds ratios (ORs) for dichotomous outcomes, and meta-analysis was performed using a fixed-effect model.

MAIN RESULTS

We included 26 studies with outcome data by hormone receptor: 12 metastatic studies (n = 4325), 6 neoadjuvant trials (n = 3152), and 8 adjuvant studies (n = 13,457). Capecitabine treatment was added in several different ways across studies. These could be classified as capecitabine alone compared to another treatment, capecitabine substituted for part of the control chemotherapy, and capecitabine added to control chemotherapy. In the metastatic setting, the effect of capecitabine was heterogenous between hormone receptor-positive and -negative tumours. For OS, no difference between capecitabine-containing and non-capecitabine-containing regimens was observed for all participants taken together (HR 1.01, 95% confidence interval (CI) 0.98 to 1.05; 12 studies, 4325 participants; high-certainty evidence), for those with hormone receptor-positive disease (HR 0.93, 95% CI 0.84 to 1.04; 7 studies, 1834 participants; high-certainty evidence), and for those with hormone receptor-negative disease (HR 1.00, 95% CI 0.88 to 1.13; 8 studies, 1577 participants; high-certainty evidence). For progression-free survival (PFS), a small improvement was seen for all people (HR 0.89, 95% CI 0.82 to 0.96; 12 studies, 4325 participants; moderate-certainty evidence). This was largely accounted for by a moderate improvement in PFS for inclusion of capecitabine in hormone receptor-positive cancers (HR 0.82, 95% CI 0.73 to 0.91; 7 studies, 1594 participants; moderate-certainty evidence) compared to no difference in PFS for hormone receptor-negative cancers (HR 0.96, 95% CI 0.83 to 1.10; 7 studies, 1122 participants; moderate-certainty evidence). Quality of life was assessed in five studies; in general there did not seem to be differences in global health scores between the two treatment groups at around two years' follow-up. Neoadjuvant studies were highly variable in design, having been undertaken to test various experimental regimens using pathological complete response (pCR) as a surrogate for disease-free survival (DFS) and OS. Across all patients, capecitabine-containing regimens resulted in little difference in pCR in comparison to non-capecitabine-containing regimens (odds ratio (OR) 1.12, 95% CI 0.94 to 1.33; 6 studies, 3152 participants; high-certainty evidence). By subtype, no difference in pCR was observed for either hormone receptor-positive (OR 1.22, 95% CI 0.76 to 1.95; 4 studies, 964 participants; moderate-certainty evidence) or hormone receptor-negative tumours (OR 1.28, 95% CI 0.61 to 2.66; 4 studies, 646 participants; moderate-certainty evidence). Four studies with 2460 people reported longer-term outcomes: these investigators detected no difference in either DFS (HR 1.02, 95% CI 0.86 to 1.21; high-certainty evidence) or OS (HR 0.97, 95% CI 0.77 to 1.23; high-certainty evidence). In the adjuvant setting, a modest improvement in OS was observed across all participants (HR 0.89, 95% CI 0.81 to 0.98; 8 studies, 13,547 participants; moderate-certainty evidence), and no difference in OS was seen in hormone receptor-positive cancers (HR 0.86, 95% CI 0.68 to 1.09; 3 studies, 3683 participants), whereas OS improved in hormone receptor-negative cancers (HR 0.72, 95% CI 0.59 to 0.89; 5 studies, 3432 participants). No difference in DFS or relapse-free survival (RFS) was observed across all participants (HR 0.93, 95% CI 0.86 to 1.01; 8 studies, 13,457 participants; moderate-certainty evidence). As was observed for OS, no difference in DFS/RFS was seen in hormone receptor-positive cancers (HR 1.03, 95% CI 0.91 to 1.17; 5 studies, 5604 participants; moderate-certainty evidence), and improvements in DFS/RFS with inclusion of capecitabine were observed for hormone receptor-negative cancers (HR 0.74, 95% CI 0.64 to 0.86; 7 studies, 3307 participants; moderate-certainty evidence). Adverse effects were reported across all three scenarios. When grade 3 or 4 febrile neutropenia was considered, no difference was seen for capecitabine compared to non-capecitabine regimens in neoadjuvant studies (OR 1.31, 95% CI 0.97 to 1.77; 4 studies, 2890 participants; moderate-certainty evidence), and a marked reduction was seen for capecitabine in adjuvant studies (OR 0.55, 95% CI 0.47 to 0.64; 5 studies, 8086 participants; moderate-certainty evidence). There was an increase in diarrhoea and hand-foot syndrome in neoadjuvant (diarrhoea: OR 1.95, 95% CI 1.32 to 2.89; 3 studies, 2686 participants; hand-foot syndrome: OR 6.77, 95% CI 4.89 to 9.38; 5 studies, 3021 participants; both moderate-certainty evidence) and adjuvant trials (diarrhoea: OR 2.46, 95% CI 2.01 to 3.01; hand-foot syndrome: OR 13.60, 95% CI 10.65 to 17.37; 8 studies, 11,207 participants; moderate-certainty evidence for both outcomes).

AUTHORS' CONCLUSIONS

In summary, a moderate PFS benefit by including capecitabine was seen only in hormone receptor-positive cancers in metastatic studies. No benefit of capecitabine for pCR was noted overall or in hormone receptor subgroups when included in neoadjuvant therapy. In contrast, the addition of capecitabine in the adjuvant setting led to improved outcomes for OS and DFS in hormone receptor-negative cancer. Future studies should stratify by hormone receptor and triple-negative breast cancer (TNBC) status to clarify the differential effects of capecitabine in these subgroups across all treatment scenarios, to optimally guide capecitabine inclusion.

Trial Watch: Tumor-targeting monoclonal antibodies in cancer therapy

In 1997, for the first time in history, a monoclonal antibody (mAb), i.e., the chimeric anti-CD20 molecule rituximab, was approved by the US Food and Drug Administration for use in cancer patients. Since then, the panel of mAbs that are approved by international regulatory agencies for the treatment of hematopoietic and solid malignancies has not stopped to expand, nowadays encompassing a stunning amount of 15 distinct molecules. This therapeutic armamentarium includes mAbs that target tumor-associated antigens, as well as molecules that interfere with tumor-stroma interactions or exert direct immunostimulatory effects. These three classes of mAbs exert antineoplastic activity via distinct mechanisms, which may or may not involve immune effectors other than the mAbs themselves. In previous issues of OncoImmunology, we provided a brief scientific background to the use of mAbs, all types confounded, in cancer therapy, and discussed the results of recent clinical trials investigating the safety and efficacy of this approach. Here, we focus on mAbs that primarily target malignant cells or their interactions with stromal components, as opposed to mAbs that mediate antineoplastic effects by activating the immune system. In particular, we discuss relevant clinical findings that have been published during the last 13 months as well as clinical trials that have been launched in the same period to investigate the therapeutic profile of hitherto investigational tumor-targeting mAbs.

Targeting the Breast Cancer Kinome

Protein kinases are highly tractable targets for the treatment of many cancers including breast cancer, due to their essential role in tumor cell proliferation and survival. Sequencing of the breast cancer genome and transcriptome has defined breast cancer as a heterogeneous disease that is classified into five molecular subtypes: luminal A, luminal B, HER2-enriched, basal-like, and claudin-low. Each subtype displays a unique expression profile of protein kinases that can be targeted by small molecule kinase inhibitors or biologics. An understanding of genomic changes, including mutations or copy number variations, for specific protein kinases and dependencies on kinases across breast cancer subtypes is allowing for a more rational design of targeted breast cancer therapies. While specific kinase inhibitors have had success in the clinic, including the CDK4/6 inhibitor palbociclib in combination with aromatase inhibitors in luminal breast cancer, patients often become resistant to treatment. An understanding of the mechanisms allowing cells to bypass targeted kinase inhibition has led to the development of combination therapies that are more durable in pre-clinical studies. However, the heterogeneity of resistance mechanisms and rapid adaptability of the kinome through feedback regulation greatly inhibit the long-term efficacy of combination kinase inhibitor therapies. It is becoming apparent that epigenetic inhibitors, such as HDAC and BET bromodomain inhibitors can block the transcriptional adaptability of tumor cells to kinase inhibitors and prevent the onset of resistance. Such novel combination therapies are currently showing promise in preclinical studies to markedly increase the durability of kinase inhibitors in breast cancer. J. Cell. Physiol. 232: 53-60, 2017. © 2016 Wiley Periodicals, Inc.

Bevacizumab: a review of its use in advanced cancer

The humanized monoclonal antibody bevacizumab (Avastin(®)) has been available in the EU since 2005. Results of phase III trials demonstrate that adding intravenous bevacizumab to antineoplastic agents improves progression-free survival and/or overall survival in patients with advanced cancer, including when used as first- or second-line therapy in metastatic colorectal cancer, as first-line therapy in advanced nonsquamous non-small cell lung cancer, as first-line therapy in metastatic renal cell carcinoma, as first-line therapy in metastatic breast cancer, and as first-line therapy in epithelial ovarian, fallopian tube or primary peritoneal cancer or in recurrent, platinum-sensitive or platinum-resistant disease. Results of these studies are supported by the findings of routine oncology practice studies conducted in real-world settings. The tolerability profile of bevacizumab is well defined and adverse events associated with its use (e.g. hypertension, proteinuria, haemorrhage, wound healing complications, arterial thromboembolism, gastrointestinal perforation) are generally manageable. In conclusion, bevacizumab remains an important option for use in patients with advanced cancer.

Paclitaxel and bevacizumab with or without capecitabine as first-line treatment for HER2-negative locally recurrent or metastatic breast cancer: a multicentre, open-label, randomised phase 2 trial

BACKGROUND

The addition of bevacizumab to paclitaxel or capecitabine has demonstrated improved progression-free survival (PFS) and objective response rate (ORR) as compared with chemotherapy alone in patients with HER2-negative locally recurrent or metastatic breast cancer (LR/MBC). We evaluated the efficacy and safety of first-line therapy of paclitaxel and bevacizumab with or without capecitabine in patients with HER2-negative LR/MBC.

METHODS

In this multicentre, open-label, randomised phase II trial, women with HER2-negative LR/MBC were randomly assigned in a 1:1 ratio to paclitaxel (90 mg/m2 intravenously [IV] on days 1, 8, and 15) and bevacizumab (10 mg/kg IV on days 1 and 15) every 4 weeks for six cycles, followed by bevacizumab (15 mg/kg IV on day 1) every 3 weeks (AT) or to paclitaxel (90 mg/m2 IV on days 1 and 8), bevacizumab (15 mg/kg IV on day 1) and capecitabine (825 mg/m2 orally twice daily on days 1–14) every 3 weeks for eight cycles, followed by bevacizumab and capecitabine at the same doses every 3 weeks (ATX). The primary end-point was investigator-assessed PFS. Secondary end-points included ORR, duration of response, overall survival (OS) and safety. Exploratory analyses were conducted to evaluate the impact of capecitabine on OS and to validate a novel prognostic model. This trial is registered with EudraCT, number 2006-006058-83.

FINDINGS

Median PFS was significantly longer in ATX as compared with AT (11.2 months versus 8.4 months; stratified hazard ratio (HR), 0.52; 95% confidence interval (CI), 0.41–0.67; p < 0.0001). The ORR in ATX patients with measurable disease (n = 268) was higher than that in AT (69% versus 51%; p = 0.01). The median duration of response was 6.8 versus 5.4 months for, respectively, ATX and AT (p < 0.0001). Median OS was 24.2 months for ATX and 23.1 months for AT (p = 0.53). The increased rate of grade 3–4 adverse events related to the addition of capecitabine, being hand-foot syndrome (34% versus 0% for AT) and neutropenia (20% versus 12% for AT), generally did not preclude continuation of treatment. Exploratory analyses indicated that (1) patients receiving capecitabine at some line for treatment have significantly improved OS and (2) a prognostic model can classify patients into three risk groups associated with OS.

INTERPRETATION

In patients with HER2-negative LR/MBC, addition of capecitabine to paclitaxel and bevacizumab significantly improved PFS, ORR and response duration. This combination was reasonably well tolerated and may be considered of use as first-line treatment in rapidly progressive disease.

FUNDING

F. Hoffmann-La Roche Ltd, the Netherlands.

[New targeted therapies in breast cancer]

Trastuzumab improves care of patients with HER2+ breast cancer and allows a major gain in terms of survival. T-DM1 and pertuzumab are two new treatments, which give very encouraging results in metastatic breast cancer. Their place in neo-adjuvant and adjuvant setting still remains to be defined. Bevacizumab have its place in metastatic breast cancer. In adjuvant setting, results are disappointing and in neo-adjuvant setting, we need more studies on subgroups, which can benefit more. Development of the PARP inhibitors was slowed down by recent negative results in metastatic breast cancer but studies continue with more targeted patient's. Finally, everolimus, inhibitor of mTOR, allows to by pass the hormono-resistance in metastatic phase. Its toxicity must be taken into account in particular in adjuvant setting.

The life, death, and attempted rebirth of bevacizumab in breast cancer

Breast cancer is the leading cause of cancer in women. In recent years, there has been immense drug discovery and development in the field of breast cancer. Most recently, the role of vascular endothelial growth factor has moved to the treatment forefront with bevacizumab immersed into the literature as well as the media. Bevacizumab, a vascular endothelial growth factor inhibitor FDA approved for the treatment of other cancers, was first studied in metastatic breast cancer. Its use in human epidermal growth factor receptor 2–negative metastatic breast cancer ultimately failed to show an improvement in overall survival in landmark trials (E2100, AVADO, RIBBON-1 and RIBBON-2) despite its positive impact on progression-free survival. The role is yet to be determined in triple negative breast cancer as well as in the adjuvant and neoadjuvant settings. Trends begin to emerge as bevacizumab is combined with other chemotherapeutic drugs in terms of toxicities. The addition of bevacizumab is associated with an increase in the dose-limiting toxicities of the drugs combined in the regimen. As previous literature suggest, hypertension and proteinuria were also seen with the addition of bevacizumab, both of which are known adverse events. Lastly, there is a trend towards increased incidence of heart failure when bevacizumab is combined with another cardiotoxic medication, doxorubicin. This toxicity has been shown to be reversible in the majority of the cases and has a low incidence in the currently published literature.

Present status and problems on molecular targeted therapy of cancer

Numerous clinical trials of molecular targeted drugs for cancer have been conducted, with remarkable results for certain drugs and accumulation of "negative data" causing a hitch in the development plan for some other compounds. Five recent issues and problems of molecular targeted therapies were discussed critically. Drug discovery and effects against driver mutations (activating mutations) and problems: possibility for circumventing inherent and acquired resistance with the aim of achieving radical cure. Synthetic lethality: reasonable patient selection in individualized treatment strategy. Response rate and progression-free survival improvement with or without overall survival benefit and enhancement of toxicity in bevacizumab therapy: best endpoints for the evaluation of effect of antiangiogenic therapy. Negative data on small-molecule targeted therapy, primarily vascular endothelial growth factor tyrosine kinase inhibitors: loose GO or NO-GO decision criteria for further development of new compounds in early clinical trials. Effect of immunotherapy: difficulty to verify by proof of principle study. We are faced to many questions for the development of efficient personalized therapy. Accumulation of scientific global preclinical and clinical evidences is essential to use these new therapeutic modalities for the improvement of oncologic health care.

Bevacizumab: a review of its use in combination with paclitaxel or capecitabine as first-line therapy for HER2-negative metastatic breast cancer

Bevacizumab (Avastin™) is a humanized monoclonal antibody directed against vascular endothelial growth factor. In patients with human epidermal growth factor receptor type 2 (HER2)-negative metastatic breast cancer, bevacizumab is indicated as first-line therapy in combination with paclitaxel, or in combination with capecitabine when treatment with other chemotherapy options, including taxanes or anthracyclines, is not considered appropriate. This article reviews the efficacy and tolerability of these combination therapies in the first-line treatment of patients with metastatic breast cancer, and summarizes the pharmacological properties of bevacizumab. In randomized, controlled, phase III trials in patients with predominantly HER2-negative metastatic or locally recurrent breast cancer, the addition of bevacizumab to paclitaxel or capecitabine significantly prolonged progression-free survival (PFS; investigator assessment) by a median of 5.9 and 2.9 months, respectively, relative to paclitaxel or capecitabine alone. It also significantly increased the objective response rate, but not overall survival. Independent reviews of data supported the results of the primary analyses of investigator-assessed PFS. However, as the efficacy of bevacizumab in combination with capecitabine appears to be less than that of other available options, it should be used only if treatment with other chemotherapy options are not considered appropriate. The addition of bevacizumab to paclitaxel had no significant adverse effects on health-related quality of life. Efficacy data from two routine clinical practice studies were generally consistent with those from the phase III trials. Bevacizumab had generally acceptable tolerability when administered in combination with paclitaxel or capecitabine as first-line therapy in these studies, and adverse events were consistent with the known tolerability profiles of the individual agents. The most common adverse events associated with bevacizumab combination therapy in phase III trials were sensory neuropathy and grade ≥3 hypertension, occurring more frequently with combination therapy than with chemotherapy alone. Potentially life-threatening events, such as venous thromboembolism, gastrointestinal perforation, arterial thromboembolism, haemorrhage and left ventricular dysfunction, occurred in ≤5% of patients receiving combination therapy in these trials. In conclusion, bevacizumab administered in combination with paclitaxel, or in combination with capecitabine if other chemotherapy regimens are not appropriate, may be considered as an option for the first-line treatment of patients with HER2-negative metastatic breast cancer.