The Role of Mammalian Target of Rapamycin (mTOR) Inhibition in the Treatment of Advanced Breast Cancer

Antitumor response and quality of life: is there a need to sacrifice? Clinical observation: long-term and safe control of the disease using a combination of ribociclib with letrozole. Case report

Metastatic luminal B HER2-negative breast cancer (HR+/HER2- mBC) occupies a leading place in the global structure of morbidity and mortality among women. The current gold standard of first-line treatment is the combination of CDK4/6 inhibitors with aromatase inhibitors, among which ribociclib with letrozole is distinguished. According to the MONALEESA-2 study, the addition of ribociclib to letrozole significantly increased the median overall survival to 63.9 months, reducing the risk of death by 24%. The safety profile of the combination is manageable, and the development of adverse events led to the interruption of therapy only in 7.5% of cases. A study of the actual clinical practice of CompLEEment-1 also confirmed the safety and effectiveness of the combination. Maintaining and improving the quality of life is one of the main tasks in the treatment of patients with HR+/HER2- mBC. According to the MONALEESA-2 study, the addition of ribociclib significantly affects the maintenance of quality of life and leads to a decrease in the intensity of pain syndrome. The published data allowed us to assign a combination of ribociclib and letrozole 4 points on the ESMO-MCBS scale. The safety of long-term use of the combination in the first line of treatment illustrated by clinical observation. The patient's progression-free survival during therapy was 40 months, which significantly exceeds the data of the MONALEESA-2 and CompLEEment-1 studies. The maximum effect (partial response according to RECIST 1.1 -40%) achieved after 24 weeks and persisted for 24 months. Clinically, the patient noted a decrease in the severity of the pain syndrome after 8 weeks of therapy. Against the background of therapy, it was possible to maintain the quality of life without sacrificing antitumor efficacy.

Real-Life Analysis of Efficacy and Safety of Everolimus Plus Exemestane in Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor-2-Negative Metastatic Breast Cancer Patients: A Turkish Oncology Group (TOG) Study

PURPOSE

This study evaluated the efficacy and safety of everolimus (EVE) plus exemestane (EXE) in hormone-receptor positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) metastatic breast cancer (MBC) patients in real-life settings.

METHODS

Overall, 204 HR+, HER2- MBC patients treated with EVE + EXE after progressing following prior endocrine treatment were included. Overall survival (OS) and progression-free survival (PFS) and safety data were analyzed.

RESULTS

The objective response rate, median PFS, and median OS were 33.4%, 8.9 months, and 23.4 months, respectively. Multivariate analysis revealed that negative progesterone receptor status was a significant determinant of poor treatment response (p = 0.035) and PFS (p = 0.024). The presence of bone-only metastasis was associated with better treatment response (p = 0.002), PFS (p < 0.001), and OS (p = 0.001).

CONCLUSION

We confirmed the favorable efficacy and safety profile of EVE + EXE for HR+, HER - MBC patients.

Synthesis and validation of [18F]mBPET-1, a fluorine-18 labelled mTOR inhibitor derivative based on a benzofuran backbone

Background

Targeted therapy of HER2 positive breast cancer has led to clinical success in some cases with primary and secondary resistance being major obstacles. Due to the substantial involvement of mTOR kinase in cell growth and proliferation pathways it is now targeted in combination treatments to counteract HER2 targeted therapy resistance. However, the selection of receptive patient populations for a specific drug combination is crucial. This work aims to develop a molecular probe capable of identifying patients with tumour populations which are receptive to RAD001 combination therapy. Based on the structure of a mTOR inhibitor specific for mTORC1, we designed, synthesised and characterised a novel benzofuran based molecular probe which suits late stage fluorination via Click chemistry.

Results

Synthesis of the alkyne precursor 5 proceeded in 27.5% yield over 7 linear steps. Click derivatisation gave the non-radioactive standard in 25% yield. Radiosynthesis of [¹⁸F]1-((1-(2-Fluoroethyl)-1H-1,2,3-triazol-4-yl) methyl)-4-((5-methoxy-2-phenylbenzofuran-4-yl) methyl) piperazine ([¹⁸F]mBPET-1) proceeded over two steps which were automated on an iPhase FlexLab synthesis module. In the first step, 2-[¹⁸F]fluoroethylazide ([¹⁸F]6) was produced, purified by automated distillation in 60% non-decay-corrected yield and subjected to Click conditions with 5. Semi-preparative RP-HPLC purification and reformulation gave [¹⁸F]mBPET-1 in 40% ± 5% (n = 6) overall RCY with a process time of 90 min. Radiochemical purity was ≥99% at end of synthesis (EOS) and ≥ 98% after 4 h at room temperature. Molar activities ranged from typically 24.8 GBq/μmol (EOS) to a maximum of 78.6 GBq/μmol (EOS). Lipophilicity of [¹⁸F]mBPET-1 was determined at pH 7.4 (logD_7.4 = 0.89). [¹⁸F]mBPET-1 showed high metabolic stability when incubated with mouse S9 liver fractions which resulted in a 0.8% drop in radiochemical purity after 3 h. Cell uptake assays showed 1.3–1.9-fold increased uptake of the [¹⁸F]mBPET-1 in RAD001 sensitive compared to insensitive cells across a panel of 4 breast cancer cell lines.

Conclusion

Molecular targeting of mTOR with [¹⁸F]mBPET-1 distinguishes mTOR inhibitor sensitive and insensitive cell lines. Future studies will explore the ability of [¹⁸F]mBPET-1 to predict response to mTOR inhibitor treatment in in vivo models.

Mono-(2-ethylhexyl) phthalate induced ROS-dependent autophagic cell death in human vascular endothelial cells

Mono-(2-ethylhexyl) phthalate (MEHP) is an active metabolite of di-(2-ethylhexyl) phthalate (DEHP). MEHP has toxic effects on cardiovascular system, but the possible molecular mechanisms are not completely elucidated. In our study, 3-methyladenine (3-MA), an autophagosome formation inhibitor, protected the EA.hy926 cells against MEHP cytotoxicity, and rapamycin, an autophagosome formation stimulator, further decreased the cell viability in the MEHP-treated EA.hy926 cells. Thus, autophagy may play an important role in MEHP-induced toxicity. MEHP increased the autophagosome number in EA.hy926 cells detected under transmission electron microscope. Collapses of ΔΨm and reactive oxygen species (ROS) level were increased in a dose-dependent manner under treatment with 0-200μM MEHP for 24h. N-acetyl-l-cysteine (NAC), a ROS inhibitor, protected against MEHP-induced cytotoxicity and decreased the protein expression of LC3-II. These findings suggested that MEHP-induced autophagic cell death was ROS-dependent in EA.hy926 cells. Knockdown of Akt1 with Akt1 siRNA aggravated MEHP-induced cell death, and insulin, an Akt1 activator, alleviated MEHP-induced cell death. These results were consistent with the expression of LC3-II using western blot. The phospho-Akt1^(Ser473) (p-Akt1) level was enhanced after pretreatment with NAC. In conclusion, it is possible that ROS elicited autophagy through Akt1 pathway in the MEHP-treated EA.hy926 cells.

Everolimus Plus Exemestane in Advanced Breast Cancer: Safety Results of the BALLET Study on Patients Previously Treated Without and with Chemotherapy in the Metastatic Setting

BACKGROUND

The BALLET study was an open-label, multicenter, expanded access study designed to allow treatment with everolimus plus exemestane in postmenopausal women with hormone receptor-positive metastatic breast cancer progressed following prior endocrine therapy. A post hoc analysis to evaluate if previous chemotherapy in the metastatic setting affects the safety profile of the combination regimen of everolimus and exemestane was conducted on the Italian subset, as it represented the major part of the patients enrolled (54%).

PATIENTS AND METHODS

One thousand one hundred and fifty-one Italian patients were included in the present post hoc analysis, which focused on two sets of patients: patients who never received chemotherapy in the metastatic setting (36.1%) and patients who received at least one chemotherapy treatment in the metastatic setting (63.9%).

RESULTS

One thousand one hundred and sixteen patients (97.0%) prematurely discontinued the study drug, and the main reasons reported were disease progression (39.1%), local reimbursement of everolimus (31.1%), and adverse events (AEs) (16.1%). The median duration of study treatment exposure was 139.5 days for exemestane and 135.0 days for everolimus. At least one AE was experienced by 92.5% of patients. The incidence of everolimus-related AEs was higher (83.9%) when compared with those that occurred with exemestane (29.1%), and the most commonly reported everolimus-related AE was stomatitis (51.3%). However, no significant difference in terms of safety related to the combination occurred between patients without and with chemotherapy in the metastatic setting.

CONCLUSION

Real-life data of the Italian patients BALLET-related cohort were an adequate setting to state that previous chemotherapy did not affect the safety profile of the combination regimen of everolimus and exemestane.

IMPLICATIONS FOR PRACTICE

With the advent of new targeted agents for advanced or metastatic breast cancer, multiple lines of therapy may be possible, and components of the combined regimens can overlap from one line to another. Thus, it is important to assess even the potential of cumulative and additive toxic effects among the drugs. Previous chemotherapy did not affect the safety profile of the combination regimen of everolimus and exemestane. The continuous monitoring of the safety signals of this drug combination from general clinical practice is important, in particular for stomatitis.

Phase II, randomized, placebo-controlled study of dovitinib in combination with fulvestrant in postmenopausal patients with HR+, HER2- breast cancer that had progressed during or after prior endocrine therapy

Background

Overexpression of fibroblast growth factor receptor 1 (FGFR1), found in ≤8% of hormone receptor–positive (HR⁺), human epidermal growth factor receptor 2–negative (HER2⁻) breast cancer cases, is correlated with decreased overall survival and resistance to endocrine therapy (ET). Dovitinib, a potent FGFR inhibitor, has demonstrated antitumor activity in heavily pretreated patients with FGFR pathway–amplified breast cancer.

Methods

In this randomized, placebo-controlled phase II trial, we evaluated whether the addition of dovitinib to fulvestrant would improve outcomes in postmenopausal patients with HR⁺, HER2⁻ advanced breast cancer that had progressed during or after prior ET. Patients were stratified by FGF pathway amplification and presence of visceral disease, and they were randomized 1:1 to receive fulvestrant plus dovitinib or placebo. The primary endpoint was progression-free survival (PFS).

Results

From 15 May 2012 to 26 November 2014, 97 patients from 36 centers were enrolled. The frequency of FGF pathway amplification was lower than anticipated, and the study was terminated early owing to slow accrual of patients with FGF pathway amplification. The median PFS (95% CI) was 5.5 (3.8–14.0) months vs 5.5 (3.5–10.7) months in the dovitinib vs placebo arms, respectively (HR, 0.68; did not meet predefined efficacy criteria). For the FGF pathway–amplified subgroup (n = 31), the median PFS (95% CI) was 10.9 (3.5–16.5) months vs 5.5 (3.5–16.4) months in the dovitinib vs placebo arms, respectively (HR, 0.64; met the predefined superiority criteria). Frequently reported adverse events in the dovitinib (diarrhea, nausea, vomiting, asthenia, and headache) and placebo (diarrhea, fatigue, nausea, and asthenia) arms were mostly low grade.

Conclusions

The safety profile of dovitinib plus fulvestrant was consistent with the known safety profile of single-agent dovitinib. Dovitinib in combination with fulvestrant showed promising clinical activity in the FGF pathway–amplified subgroup. However, the data reported herein should be interpreted with caution, given that fewer PFS events occurred in the FGF pathway–amplified patients than was expected and that an effect of dovitinib regardless of FGR pathway amplification status cannot be excluded, because the population was smaller than expected.

Trial registration

ClinicalTrials.gov identifier: NCT01528345. Registered 31 January 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0807-8) contains supplementary material, which is available to authorized users.

17β-Estradiol Promotes Schwann Cell Proliferation and Differentiation, Accelerating Early Remyelination in a Mouse Peripheral Nerve Injury Model

Estrogen induces oligodendrocyte remyelination in response to demyelination in the central nervous system. Our objective was to determine the effects of 17β-estradiol (E2) on Schwann cell function and peripheral nerve remyelination after injury. Adult male C57BL/6J mice were used to prepare the sciatic nerve transection injury model and were randomly categorized into control and E2 groups. To study myelination in vitro, dorsal root ganglion (DRG) explant culture was prepared using 13.5-day-old mouse embryos. Primary Schwann cells were isolated from the sciatic nerves of 1- to 3-day-old Sprague–Dawley rats. Immunostaining for myelin basic protein (MBP) expression and toluidine blue staining for myelin sheaths demonstrated that E2 treatment accelerates early remyelination in the “nerve bridge” region between the proximal and distal stumps of the transection injury site in the mouse sciatic nerve. The 5-bromo-2′-deoxyuridine incorporation assay revealed that E2 promotes Schwann cell proliferation in the bridge region and in the primary culture, which is blocked using AKT inhibitor MK2206. The in vitro myelination in the DRG explant culture determined showed that the MBP expression in the E2-treated group is higher than that in the control group. These results show that E2 promotes Schwann cell proliferation and myelination depending on AKT activation.

Rapamycin Does Not Impede Survival or Induction of Antibody Responses to Primary and Heterosubtypic Influenza Infections in Mice

Impairment of immune defenses can contribute to severe influenza infections. Rapamycin is an immunosuppressive drug often used to prevent transplant rejection and is currently undergoing clinical trials for treating cancers and autoimmune diseases. We investigated whether rapamycin has deleterious effects during lethal influenza viral infections. We treated mice with two concentrations of rapamycin and infected them with A/Puerto Rico/8/1934 (A/PR8), followed by a heterosubtypic A/Hong Kong/1/68 (A/HK68) challenge. Our data show similar morbidity, mortality, and lung viral titer with both rapamycin treatment doses compared to untreated controls, with a delay in morbidity onset in rapamycin high dose recipients during primary infection. Rapamycin treatment at high dose also led to increase in percent cytokine producing T cells in the spleen. However, all infected animals had similar serum antibody responses against A/PR8. Post-A/HK68 challenge, rapamycin had no impeding effect on morbidity or mortality and had similar serum antibody levels against A/PR8 and A/HK68. We conclude that rapamycin treatment does not adversely affect morbidity, mortality, or antibody production during lethal influenza infections.

Safety of everolimus plus exemestane in patients with hormone-receptor-positive, HER2-negative locally advanced or metastatic breast cancer progressing on prior non-steroidal aromatase inhibitors: primary results of a phase IIIb, open-label, single-arm, expanded-access multicenter trial (BALLET)

BACKGROUND

This European phase IIIb, expanded-access multicenter trial evaluated the safety of EVE plus EXE in a patient population similar to BOLERO-2.

PATIENTS AND METHODS

Post-menopausal women aged ≥18 years with hormone receptor-positive, human epidermal growth factor-receptor-2-negative advanced breast cancer (ABC) recurring/progressing during/after prior non-steroidal aromatase inhibitors were enrolled. The primary objective was safety of EVE plus EXE based on frequency of adverse events (AEs), and serious AEs (SAEs). The secondary objective was to evaluate AEs of grade 3/4 severity.

RESULTS

The median treatment duration was 5.1 months [95% confidence interval (CI) 4.8-5.6] for EVE and 5.3 months (95% CI 4.8-5.6) for EXE. Overall, 2131 patients were included in the analysis; 81.8% of patients experienced EVE- or EXE-related or EVE/EXE-related AEs (investigator assessed); 27.2% were of grade 3/4 severity. The most frequently reported non-hematologic AEs were (overall %, % EVE-related) stomatitis (52.8%; 50.8%) and asthenia (22.8%; 14.6%). The most frequently reported hematologic AEs were (overall %, % EVE-related) anemia (14.4%; 8.1%) and thrombocytopenia (5.9%; 4.6%). AE-related treatment discontinuations were higher in elderly (≥70 years) versus non-elderly patients (23.8% versus 13.0%). The incidence of EVE-related AEs in both elderly and non-elderly patients appeared to be lower in first-line ABC versus later lines. The incidence of AEs (including stomatitis/pneumonitis) was independent of BMI status (post hoc analysis). Overall, 8.5% of patients experienced at least one EVE-related SAE. Of the 121 on-treatment deaths (5.7%), 66 (3.1%) deaths were due to disease progression and 46 (2.2%) due to AEs; 4 deaths were suspected to be EVE-related.

CONCLUSIONS

This is the largest ever reported safety dataset on a general patient population presenting ABC treated with EVE plus EXE and included a sizeable elderly subset. Although the patients were more heavily pretreated, the safety profile of EVE plus EXE in BALLET was consistent with BOLERO-2.

CLINICAL TRIAL REGISTRATION

EudraCT Number: 2012-000073-23.

Everolimus restrains the paracrine pro-osteoclast activity of breast cancer cells

Background

Breast cancer (BC) cells secrete soluble factors that accelerate osteoclast (OC) differentiation, leading to the formation of osteolytic bone metastases. In the BOLERO-2 trial, BC patients with bone involvement who received Everolimus had a delayed tumor progression in the skeleton as a result of direct OC suppression through the inhibition of mTOR, in addition to the general suppressor effect on the cancer cells. Here, we explored the effect of Everolimus, as mTOR inhibitor, on the pro-OC paracrine activity of BC cells.

Methods

Both MDA-MB-231 and MCF-7 BC cell lines were incubated with sub-lethal amounts of Everolimus, and their conditioned supernatants were assessed for their capacity to differentiate OCs from PBMC from healthy donors, as well as to interfere with their bone resorbing activity shown on calcium phosphate slices. We also measured the mRNA levels of major pro-OC factors in Everolimus-treated BC cells and their secreted levels by ELISA, and evaluated by immunoblotting the phosphorylation of transcription factors enrolled by pathways cooperating with the mTOR inhibition. Finally, the in vivo pro-OC activity of these cells was assessed in SCID mice after intra-tibial injections.

Results

We found that Everolimus significantly inhibited the differentiation of OCs and their in vitro bone-resorbing activity, and also found decreases of both mRNA and secreted pro-OC factors such as M-CSF, IL-6, and IL-1β, whose lower ELISA levels paralleled the defective phosphorylation of NFkB pathway effectors. Moreover, when intra-tibially injected in SCID mice, Everolimus-treated BC cells produced smaller bone metastases than the untreated cells.

Conclusions

mTOR inhibition in BC cells leads to a suppression of their paracrine pro-OC activity by interfering with the NFkB pathway; this effect may also account for the delayed progression of bone metastatic disease observed in the BOLERO-2 trial.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1717-8) contains supplementary material, which is available to authorized users.

Potential of overcoming resistance to HER2-targeted therapies through the PI3K/Akt/mTOR pathway

Human epidermal growth factor receptor 2 (HER2) overexpression occurs in up to 30% of breast cancers and is a marker of aggressive disease. While HER2-targeted therapies have improved outcomes in these tumors, resistance to these agents develops in a large proportion of patients. Determining molecular mechanisms underlying resistance might help improve outcomes for patients with HER2-positive disease by allowing development of strategies to overcome resistance. Activation of signaling pathways involving the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway might contribute to the development of resistance to HER2-targeted therapies. Several inhibitors of this pathway are under investigation in this disease setting and phase 3 data for everolimus in combination with trastuzumab and chemotherapy in trastuzumab-refractory, advanced disease are promising. In this review, molecular mechanisms underlying resistance to HER2-targeted therapies are considered and evidence for strategies to manage resistance is evaluated, including the use of inhibitors of the PI3K/Akt/mTOR pathway.

A Case of Disease Improvement after Treatment with Everolimus plus Exemestane in a Patient with Hormone Receptor-Positive Metastatic Breast Cancer with Bone Metastases

Breast cancer is one of the most frequently diagnosed cancers and a leading cause of death in women worldwide. Despite significant advances in the treatment of hormone receptor-positive breast cancer, tumor metastasis occurs frequently and is associated with poor long-term prognosis. The mammalian target of rapamycin (mTOR) pathway plays a central role in cancer cell growth, proliferation, and resistance to endocrine therapies. Therefore, mTOR inhibitors such as everolimus in combination with nonsteroidal aromatase inhibitors might reverse endocrine resistance and improve clinical outcomes in patients. Here, we report on a case of infiltrating lobular carcinoma of the breast with metastases to the bone. Histopathologic analysis showed that the patient was estrogen and progesterone receptor positive and human epidermal growth factor-2 negative. This case represents the clinical spectrum of complications caused by metastasis: the patient experienced a considerable amount of skeletal-related complications, had previously received chemotherapy, and experienced disease progression while taking nonsteroidal aromatase inhibitors. After treatment with oral everolimus 10 mg daily plus oral exemestane 25 mg daily, the patient's disease was ameliorated. Combination therapy was well tolerated, with minimal adverse effects that were manageable with concomitant medications. Although further analyses in larger populations are necessary, the addition of everolimus to exemestane might provide an effective new treatment option for patients with bone metastasis.

Management of patients with hormone receptor-positive breast cancer with visceral disease: challenges and treatment options

Endocrine therapy is an important treatment option for women with hormone receptor-positive (HR+) advanced breast cancer (ABC), yet many tumors are either intrinsically resistant or develop resistance to these therapies. Treatment of patients with ABC presenting with visceral metastases, which is associated with a poor prognosis, is also problematic. There is an unmet need for effective treatments for this patient population. Although chemotherapy is commonly perceived to be more effective than endocrine therapy in managing visceral metastases, patients who are not in visceral crisis might benefit from endocrine therapy, avoiding chemotherapy-associated toxicities that might affect quality of life. To improve outcomes, several targeted therapies are being investigated in combination with endocrine therapy for patients with endocrine-resistant, HR+ ABC. Although available data have considered patients with HR+ ABC as a whole, there are promising data from a prespecified analysis of a Phase III study of everolimus (Afinitor(®)), a mammalian target of rapamycin (mTOR) inhibitor, in combination with exemestane (Aromasin(®)) in patients with visceral disease progressing after nonsteroidal aromatase inhibitor therapy. In this review, challenges and treatment options for management of HR+ ABC with visceral disease, including consideration of therapeutic approaches undergoing clinical investigation, will be assessed.

Citreoviridin induces ROS-dependent autophagic cell death in human liver HepG2 cells

Citreoviridin (CIT) is one of toxic mycotoxins derived from fungal species in moldy cereals. Whether CIT exerts hepatotoxicity and the precise molecular mechanisms of CIT hepatotoxicity are not completely elucidated. In this study, the inhibitor of autophagosome formation, 3-methyladenine, protected the cells against CIT cytotoxicity, and the autophagy stimulator rapamycin further decreased the cell viability of CIT-treated HepG2 cells. Knockdown of Atg5 with Atg5 siRNA alleviated CIT-induced cell death. These finding suggested the hypothesis that autophagic cell death contributed to CIT-induced cytotoxicity in HepG2 cells. CIT increased the autophagosome number in HepG2 cells observed under a transmission electron microscope, and this effect was confirmed by the elevated LC3-II levels detected through Western blot. Reduction of P62 protein levels and the result of LC3 turnover assay indicated that the accumulation of autophagosomes in the CIT-treated HepG2 cells was due to increased formation rather than impaired degradation. The pretreatment of HepG2 cells with the ROS inhibitor NAC reduced autophagosome formation and reversed the CIT cytotoxicity, indicating that CIT-induced autophagic cell death was ROS-dependent. In summary, ROS-dependent autophagic cell death of HpeG2 cells described in this study may help to elucidate the underlying mechanism of CIT cytotoxicity.

Everolimus plus exemestane as first-line therapy in HR⁺, HER2⁻ advanced breast cancer in BOLERO-2

The present exploratory analysis examined the efficacy, safety, and quality-of-life effects of everolimus (EVE) + exemestane (EXE) in the subgroup of patients in BOLERO-2 whose last treatment before study entry was in the (neo)adjuvant setting. In BOLERO-2, patients with hormone-receptor-positive (HR⁺), human epidermal growth factor receptor-2-negative (HER2⁻) advanced breast cancer recurring/progressing after a nonsteroidal aromatase inhibitor (NSAI) were randomly assigned (2:1) to receive EVE (10 mg/day) + EXE (25 mg/day) or placebo (PBO) + EXE. The primary endpoint was progression-free survival (PFS) by local assessment. Overall, 137 patients received first-line EVE + EXE (n = 100) or PBO + EXE (n = 37). Median PFS by local investigator assessment nearly tripled to 11.5 months with EVE + EXE from 4.1 months with PBO + EXE (hazard ratio = 0.39; 95 % CI 0.25–0.62), while maintaining quality of life. This was confirmed by central assessment (15.2 vs 4.2 months; hazard ratio = 0.32; 95 % CI 0.18–0.57). The marked PFS improvement in patients receiving EVE + EXE as first-line therapy for disease recurrence during or after (neo)adjuvant NSAI therapy supports the efficacy of this combination in the first-line setting. Furthermore, the results highlight the potential benefit of early introduction of EVE + EXE in the management of HR⁺, HER2⁻ advanced breast cancer in postmenopausal patients.