Letrozole in advanced breast cancer: the PO25 trial

Catalysts of Healing: A Symphony of Synthesis and Clinical Artistry in Small-Molecule Agents for Breast Cancer Alleviation

Breast cancer, characterized by its molecular intricacy, has witnessed a surge in targeted therapeutics owing to the rise of small-molecule drugs. These entities, derived from cutting-edge synthetic routes, often encompassing multistage reactions and chiral synthesis, target a spectrum of oncogenic pathways. Their mechanisms of action range from modulating hormone receptor signaling and inhibiting kinase activity, to impeding DNA damage repair mechanisms. Clinical applications of these drugs have resulted in enhanced patient survival rates, reduction in disease recurrence, and improved overall therapeutic indices. Notably, certain molecules have showcased efficacy in drug-resistant breast cancer phenotypes, highlighting their potential in addressing treatment challenges. The evolution and approval of small-molecule drugs have ushered in a new era for breast cancer therapeutics. Their tailored synthetic pathways and defined mechanisms of action have augmented the precision and efficacy of treatment regimens, paving the way for improved patient outcomes in the face of this pervasive malignancy. The present review embarks on a detailed exploration of small-molecule drugs that have secured regulatory approval for breast cancer treatment, emphasizing their clinical applications, synthetic pathways, and distinct mechanisms of action.

Cellular and molecular basis of therapeutic approaches to breast cancer

In recent decades, there has been a significant amount of research into breast cancer, with some important breakthroughs in the treatment of both primary and metastatic breast cancers. It's a well-known fact that treating breast cancer is still a challenging endeavour even though physicians have a fantastic toolset of the latest treatment options at their disposal. Due to limitations of current clinical treatment options, traditional chemotherapeutic drugs, and surgical options are still required to address this condition. In recent years, there have been several developments resulting in a wide range of treatment options. This review article discusses the cellular and molecular foundation of chemotherapeutic drugs, endocrine system-based treatments, biological therapies, gene therapy, and innovative techniques for treating breast cancer.

Meta-analyses of visceral versus non-visceral metastatic hormone receptor-positive breast cancer treated by endocrine monotherapies

Endocrine therapy (ET) is recommended as first-line therapy for the majority of patients with hormone receptor-positive (HR+), human epidermal growth factor 2-negative advanced breast cancer (ABC); however, the efficacy of ET in patients with visceral metastases (VM) versus patients whose disease is limited to non-visceral metastases (non-VM) is debated. Meta-analyses including available data from randomised controlled trials of first- and second-line endocrine monotherapies for patients with HR+ ABC were performed to address this question. In one and two-stage meta-analyses, progression-free survival (PFS), overall survival (OS), clinical benefit rate (CBR) and duration of clinical benefit (DoCB) outcomes were analysed. In the first-line meta-analysis (seven trials; n = 1988) tamoxifen and fulvestrant significantly improved PFS, OS and CBR for patients with non-VM versus those whose disease included VM. The most substantial hazard ratios were observed for fulvestrant 500 mg; 0.56 (95% confidence interval [CI] 0.45-0.70) and 0.55 (95% CI 0.42-0.72) for PFS and OS, respectively. In the second-line meta-analysis (seven trials; n = 2324), all ET combined was more effective (in terms of PFS, OS and DoCB) for non-VM versus VM. In both meta-analyses, patients with non-liver VM had better clinical outcomes than patients with liver VM for all types of ET. Patients whose disease included non-VM sites had better clinical outcomes with endocrine monotherapy compared with patients whose disease included VM. These findings may facilitate better informed treatment decision-making.

Preferences of Patients With HR+ and HER2- Breast Cancer Regarding Hormonal and Targeted Therapies in the First Line of Their Metastatic Stage: A Discrete Choice Experiment

OBJECTIVE

Some hormonal and targeted treatment options are available in the first line of metastatic HR+ & HER2- breast cancer. This study aimed to quantify the preferences of Iranian breast cancer patients regarding the levels of attributes of hypothetical treatment options.

METHODS

The discrete choice experiment included 16 orthogonally designed scenarios. A novel method (named "the World Cup") was used to offer the scenarios to the respondents. Each choice task had 2 hypothetical treatments. A conditional logit regression model was used to obtain preference estimates, based on an expected utility model without interactions between attributes.

RESULTS

A total of 78 patients with breast cancer participated in the survey. The effectiveness was the main concern of the patient, which was followed by monthly cost. Participant patients significantly preferred to avoid adverse events; preference dummy-coded estimates were reported.

CONCLUSION

Followed by the effectiveness and cost, the risk of neutropenia, stomatitis, and arthralgia was least prioritized by the respondents. The estimation for the levels of the attribute "administration mode" is not significant (P = .690). Patients with breast cancer were willing to pay significant amounts to gain the benefit of the treatments and showed a significant willingness to accept to avoid the adverse events of the treatments.

Towards an Integral Therapeutic Protocol for Breast Cancer Based upon the New H+-Centered Anticancer Paradigm of the Late Post-Warburg Era

A brand new approach to the understanding of breast cancer (BC) is urgently needed. In this contribution, the etiology, pathogenesis, and treatment of this disease is approached from the new pH-centric anticancer paradigm. Only this unitarian perspective, based upon the hydrogen ion (H+) dynamics of cancer, allows for the understanding and integration of the many dualisms, confusions, and paradoxes of the disease. The new H+-related, wide-ranging model can embrace, from a unique perspective, the many aspects of the disease and, at the same time, therapeutically interfere with most, if not all, of the hallmarks of cancer known to date. The pH-related armamentarium available for the treatment of BC reviewed here may be beneficial for all types and stages of the disease. In this vein, we have attempted a megasynthesis of traditional and new knowledge in the different areas of breast cancer research and treatment based upon the wide-ranging approach afforded by the hydrogen ion dynamics of cancer. The concerted utilization of the pH-related drugs that are available nowadays for the treatment of breast cancer is advanced.

A New and Integral Approach to the Etiopathogenesis and Treatment of Breast Cancer Based upon Its Hydrogen Ion Dynamics

Despite all efforts, the treatment of breast cancer (BC) cannot be considered to be a success story. The advances in surgery, chemotherapy and radiotherapy have not been sufficient at all. Indeed, the accumulated experience clearly indicates that new perspectives and non-main stream approaches are needed to better characterize the etiopathogenesis and treatment of this disease. This contribution deals with how the new pH-centric anticancer paradigm plays a fundamental role in reaching a more integral understanding of the etiology, pathogenesis, and treatment of this multifactorial disease. For the first time, the armamentarium available for the treatment of the different types and phases of BC is approached here from a Unitarian perspective-based upon the hydrogen ion dynamics of cancer. The wide-ranged pH-related molecular, biochemical and metabolic model is able to embrace most of the fields and subfields of breast cancer etiopathogenesis and treatment. This single and integrated approach allows advancing towards a unidirectional, concerted and synergistic program of treatment. Further efforts in this line are likely to first improve the therapeutics of each subtype of this tumor and every individual patient in every phase of the disease.

Understanding the benefits and challenges of first-line cyclin-dependent kinases 4 and 6 inhibitors in advanced breast cancer among postmenopausal women

Endocrine therapy (ET) has been regarded for many years as the standard treatment for patients with hormone receptor-positive (ER+), HER2-negative (HER2-) advanced breast cancer (ABC) without visceral crisis. However, the efficacy of single-agent ET is constrained by the development of resistance, attributed to alterations in several intracellular signaling pathways, including those related to cell cycle dysregulation. The cyclin-dependent kinases 4 and 6 (CDK4/6) are principal regulators of cell cycle progression from the G1-phase into the DNA synthesis (S)-phase. In vitro inhibition of CDK4/6 activity has potent antiproliferative properties against luminal breast cancer cell lines, which are enhanced when combined with traditional ET. This has led to a substantial interest in targeting this pathway to overcome endocrine resistance in the clinic. Three selective CDK4/6 inhibitors (palbociclib, ribociclib, and abemaciclib) have been approved as first-line therapy in combination with an aromatase inhibitor, or fulvestrant in the case of ribociclib in patients with ER+/HER2- ABC. To date, there is no clue as to which subgroup of patients might benefit most from these combinations. Here, we outline some of the established approaches to overcome endocrine resistance, with special emphasis on the unique mechanism of action of CDK4/6 inhibitors.

Recent advances in breast cancer research impacting clinical diagnostic practice

During the last decade, the genomics revolution has driven critical advances in molecular oncology and pathology, and a deeper appreciation of heterogeneity that is beginning to reshape our thinking around diagnostic classification. Recent developments have seen existing classification systems modified and improved where possible, gene-based diagnostics implemented and tumour-immune interactions modulated. We present a detailed discussion of this progress, including advances in the understanding of breast tumour classification, e.g. mixed ductal-lobular tumours and the spectrum of triple-negative breast cancer. The latest information on clinical trials and the implementation of gene-based diagnostics, including MammaPrint and Oncotype Dx and others, is synthesised, and emerging targeted therapies, as well as the burgeoning immuno-oncology field, and their relevance in breast cancer, are discussed. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Fulvestrant plus goserelin versus anastrozole plus goserelin versus goserelin alone for hormone receptor-positive, HER2-negative tamoxifen-pretreated premenopausal women with recurrent or metastatic breast cancer (KCSG BR10-04): a multicentre, open-label, three-arm, randomised phase II trial (FLAG study)

BACKGROUND

We investigated the efficacy and safety of fulvestrant plus goserelin (F + G) versus anastrozole plus goserelin (A + G) in comparison with goserelin (G) alone in premenopausal women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), tamoxifen-pretreated metastatic breast cancer (MBC).

PATIENTS AND METHODS

In this multicentre, open-label, randomised phase II study, premenopausal women aged ≥18 years with HR+, HER2-, tamoxifen-pretreated MBC were randomly assigned (1:1:1) to F + G, A + G or G alone. The primary end-point was time to progression (TTP). Secondary end-points included overall survival, overall response rate, clinical benefit rate and toxicity.

RESULTS

Of 138 eligible patients, 44 were randomly assigned to receive F + G, 47 to A + G and 47 to G alone. The median follow-up duration was 32.2 months (interquartile range: 23.69-40.86) and the median age was 43.0 years (range 23.0-55.0). The median TTP was 16.3 months (95% confidence interval [CI] 7.5-25.1) for F + G, 14.5 months (95% CI 11.0-18.0) for A + G and 13.5 months (95% CI 10.3-16.8) for G alone. Compared with G alone, the hazard ratios were 0.608 for F + G (95% CI, 0.370-0.998; p = 0.049) and 0.982 for A + G (95% CI, 0.624-1.546; p = 0.937). In terms of visceral metastasis, a stratification factor, there were no TTP differences according to treatment arm. Grade III or IV toxicities were rarely observed. Of the common adverse events, grade I arthralgia and joint stiffness were more frequently observed in the F + G than in the A + G or G-alone groups (p < 0.05, respectively).

CONCLUSIONS

F + G provides a promising new option for the treatment of premenopausal women with HR+, HER2-, tamoxifen-pretreated MBC.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT01266213 and Korean Cancer Study Group (KCSG) Breast cancer protocol number BR10-04.

Efficacy and safety of endocrine monotherapy as first-line treatment for hormone-sensitive advanced breast cancer: A network meta-analysis

BACKGROUND

Endocrine therapy was recommended as the preferred first-line treatment for hormone receptor-positive (HR+, i.e., ER+ and/or PgR+), human epidermal growth factor receptor-2-negative (HER2-) postmenopausal advanced breast cancer (ABC), but which endocrine monotherapy is optimal lacks consensus. We aimed to identify the optimal endocrine monotherapy with a network meta-analysis.

METHODS

We performed a network meta-analysis for a comprehensive analysis of 6 first-line endocrine monotherapies (letrozole, anastrozole, exemestane, tamoxifen, fulvestrant 250 mg and 500 mg) for HR+ HER2- metastatic or locally advanced breast cancer in postmenopausal patients. The main outcomes were objective response rate (ORR), time to progression (TTP), and progression-free survival (PFS). Secondary outcomes were adverse events.

RESULTS

We identified 27 articles of 8 randomized controlled trials including 3492 patients in the network meta-analysis. For ORR, the treatments ranked in descending order of effectiveness were letrozole > exemestane > anastrozole > fulvestrant 500 mg > tamoxifen > fulvestrant 250 mg. For TTP/PFS, the order was fulvestrant 500 mg > letrozole > anastrozole > exemestane > tamoxifen > fulvestrant 250 mg. We directly compared adverse events and found that tamoxifen produced more hot flash events than fulvestrant 250 mg.

CONCLUSIONS

Fulvestrant 500 mg and letrozole might be optimal first-line endocrine monotherapy choices for HR+ HER2- ABC because of efficacious ORR and TTP/PFS, with a favorable tolerability profile. However, direct comparisons among endocrine monotherapies in the first-line therapy setting are still required to robustly demonstrate any differences among these endocrine agents. Clinical choices should also depend on the specific disease situation and duration of endocrine therapy.

Progression-Free Survival and Time to Progression as Real Surrogate End Points for Overall Survival in Advanced Breast Cancer: A Meta-Analysis of 37 Trials

BACKGROUND

Progression-free survival (PFS) and time to progression (TTP) have been reported to correlate with overall survival (OS) in several cancer types. To our knowledge, however, the correlation between them is unclear.

METHODS

A literature-based meta-analysis was performed to assess whether PFS and TTP can be considered reliable surrogate end points for OS in a phase 3 clinical trial of advanced breast cancer (ABC). The median hazard ratios of PFS/TTP and OS were analyzed by determining their nonparametric Spearman rank correlation coefficients (Rs).

RESULTS

A total of 37 trials with 38 treatment arms and 14,966 patients were selected for analysis. The Rs between the median PFS/TTP and OS was 0.405 (95% confidence interval [CI], 0.191-0.582; P = .003), and the correlation coefficient between the hazard ratios of PFS/TTP and OS was 0.555 (95% CI, 0.277-0.748; P = .003). PFS/TTP was closely correlated with OS in the trials of targeted therapy-based treatment (Rs = 0.872; 95% CI, 0.619-0.962; P = .0001) and of PFS/TTP or OS benefit (Rs = 0.753 and Rs = 0.821, respectively) for ABC.

CONCLUSIONS

Both PFS and TTP can be considered valid surrogate end points for OS in the trials of targeted therapy-based treatments and clinical benefits for ABC. Further research is necessary to clarify the surrogacy of PFS/TTP for OS in other trials of targeted therapy-based treatments for ABC.

Molecular Biomarkers for Prediction of Targeted Therapy Response in Metastatic Breast Cancer: Trick or Treat?

In recent years, the study of genomic alterations and protein expression involved in the pathways of breast cancer carcinogenesis has provided an increasing number of targets for drugs development in the setting of metastatic breast cancer (i.e., trastuzumab, everolimus, palbociclib, etc.) significantly improving the prognosis of this disease. These drugs target specific molecular abnormalities that confer a survival advantage to cancer cells. On these bases, emerging evidence from clinical trials provided increasing proof that the genetic landscape of any tumor may dictate its sensitivity or resistance profile to specific agents and some studies have already showed that tumors treated with therapies matched with their molecular alterations obtain higher objective response rates and longer survival. Predictive molecular biomarkers may optimize the selection of effective therapies, thus reducing treatment costs and side effects. This review offers an overview of the main molecular pathways involved in breast carcinogenesis, the targeted therapies developed to inhibit these pathways, the principal mechanisms of resistance and, finally, the molecular biomarkers that, to date, are demonstrated in clinical trials to predict response/resistance to targeted treatments in metastatic breast cancer.

Efficacy of Letrozole as First-Line Treatment of Postmenopausal Women with Hormone Receptor-Positive Metastatic Breast Cancer in Korea

Purpose

Letrozole showed efficacy and generally favorable toxicities, along with the convenience of oral administration in postmenopausal patients with hormone receptor (HR)–positive metastatic breast cancer (MBC). To the best of our knowledge, there have been no reports of the clinical outcomes in Korean patients, although letrozole is widely used in practice. Therefore, this studywas conducted to affirm the efficacy and toxicities of letrozole in Korean patients.

Materials and Methods

This study retrospectively analyzed 84 HR-positive MBC patients who had been treated with letrozole from January 2001 to December 2012. Clinicopathological characteristics and treatment history were extracted from medicalrecords. All patients received 2.5 mg letrozole once a day until there were disease progressions or unacceptable toxicity. Progression-free survival (PFS) was the primary endpoint, and secondary endpoints were overall survival (OS), objective response rate (ORR), and toxicity.

Results

The median age of the subjects was 59.3 years. Letrozole treatment resulted in a median PFS of 16.8 months (95% confidence interval [CI], 9.8 to 23.8) and a median OS of 56.4 months (95% CI, 38.1 to 74.7). The ORR was 36.9% for the 84 patients with measurable lesions. Multivariate analysis revealed symptomatic visceral disease (hazard ratio, 3.437; 95% CI, 1.576 to 7.495; p=0.002) and a disease-free interval ≤ 2 years (hazard ratio, 2.697; 95% CI, 1.262 to 5.762; p=0.010) were independently associated with shorter PFS. However, sensitivity to adjuvant hormone treatment was not related to PFS. Letrozole was generally well tolerated.

Conclusion

Letrozole showed considerable efficacy and tolerability as a first-line treatment in postmenopausal patients with HR-positive MBC.

Review of hormone-based treatments in postmenopausal patients with advanced breast cancer focusing on aromatase inhibitors and fulvestrant

Background

Endocrine therapy constitutes a central modality in the treatment of oestrogen receptor (ER)-positive advanced breast cancer.

Purpose

To evaluate the evidence for endocrine treatment in postmenopausal patients with advanced breast cancer focusing on the aromatase inhibitors, letrozole, anastrozole, exemestane and fulvestrant.

Methods

A review was carried out using PubMed. Randomised phase II and III trials reporting on ≥100 patients were included.

Results

35 trials met the inclusion criteria. If not used in the adjuvant setting, a non-steroid aromatase inhibitor was the optimal first-line option. In general, the efficacy of the different aromatase inhibitors and fulvestrant was similar in tamoxifen-refractory patients. A randomised phase II trial of palbociclib plus letrozole versus letrozole alone showed significantly increased progression-free survival (PFS) when compared with endocrine therapy alone in the first-line setting (20.2 vs 10.2 months). Furthermore, the addition of everolimus to exemestane in the Breast Cancer Trials of OraL EveROlimus-2 (BOLERO-2) study resulted in an extension of median PFS by 4.5 months after recurrence/progression on a non-steroid aromatase inhibitor. However, overall survival was not significantly increased.

Conclusion

Conventional treatment with an aromatase inhibitor or fulvestrant may be an adequate treatment option for most patients with hormone receptor-positive advanced breast cancer. Mammalian target of rapamycin (mTOR) inhibition and cyclin-dependent kinase 4/6 (CDK4/6) inhibition might represent substantial advances for selected patients in some specific settings. However, there is an urgent need for prospective biomarker-driven trials to identify patients for whom these treatments are cost-effective.

Phase III trial evaluating the addition of bevacizumab to endocrine therapy as first-line treatment for advanced breast cancer: the letrozole/fulvestrant and avastin (LEA) study

PURPOSE

To test whether combining bevacizumab, an anti-vascular endothelial growth factor treatment, with endocrine therapy (ET) could potentially delay the emergence of resistance to ET.

PATIENTS AND METHODS

A multicenter, randomized, open-label, phase III, binational (Spain and Germany) study added bevacizumab (15 mg/kg every 3 weeks) to ET (ET-B; letrozole or fulvestrant) as first-line therapy in postmenopausal patients with human epidermal growth factor receptor 2 (HER2) -negative and hormone receptor-positive advanced breast cancer. We compared progression-free survival (PFS), overall survival (OS), overall response rate (ORR), response duration (RD), time to treatment failure (TTF), clinical benefit rate (CBR), and safety.

RESULTS

From 380 patients recruited (2007 to 2011), 374 were analyzed by intent to-treat (184 patients on ET and 190 patients on ET-B). Median age was 65 years, 270 patients (72%) had Eastern Cooperative Oncology Group performance status of 0, 178 patients (48%) had visceral metastases, and 171 patients (46%) and 195 patients (52%) had received prior chemotherapy or ET, respectively. Median PFS was 14.4 months in the ET arm and 19.3 months in the ET-B arm (hazard ratio, 0.83; 95% CI, 0.65 to 1.06; P = .126). ORR, CBR, and RD with ET versus ET-B were 22% versus 41% (P < .001), 67% versus 77% (P = .041), and 13.3 months versus 17.6 months (P = .434), respectively. TTF and OS were comparable in both arms. Grade 3 to 4 hypertension, aminotransferase elevation, and proteinuria were significantly higher in the ET-B arm. Eight patients (4.2%) receiving ET-B died during study or within 30 days of end of treatment.

CONCLUSION

The addition of bevacizumab to ET in first-line treatment failed to produce a statistically significant increase in PFS or OS in women with HER2-negative/hormone receptor-positive advanced breast cancer.

Current status of hormone therapy in patients with hormone receptor positive (HR+) advanced breast cancer

The natural history of HR+ breast cancer tends to be different from hormone receptor-negative disease in terms of time to recurrence, site of recurrence and overall aggressiveness of the disease. The developmental strategies of hormone therapy for the treatment of breast cancer have led to the classes of selective estrogen receptor modulators, selective estrogen receptor downregulators, and aromatase inhibitors. These therapeutic options have improved breast cancer outcomes in the metastatic setting, thereby delaying the need for chemotherapy. However, a subset of hormone receptor-positive breast cancers do not benefit from endocrine therapy (intrinsic resistance), and all HR+ metastatic breast cancers ultimately develop resistance to hormonal therapies (acquired resistance). Considering the multiple pathways involved in the HR network, targeting other components of pathologically activated intracellular signaling in breast cancer may prove to be a new direction in clinical research. This review focuses on current and emerging treatments for HR+ metastatic breast cancer.

Alopecia with endocrine therapies in patients with cancer

BACKGROUND

Whereas the frequency of alopecia to cytotoxic chemotherapies has been well described, the incidence of alopecia during endocrine therapies (i.e., anti-estrogens, aromatase inhibitors) has not been investigated. Endocrine agents are widely used in the treatment and prevention of many solid tumors, principally those of the breast and prostate. Adherence to these therapies is suboptimal, in part because of toxicities. We performed a systematic analysis of the literature to ascertain the incidence and risk for alopecia in patients receiving endocrine therapies.

METHODS

An independent search of citations was conducted using the PubMed database for all literature as of February 2013. Phase II-III studies using the terms "tamoxifen," "toremifene," "raloxifene," "anastrozole," "letrozole," "exemestane," "fulvestrant," "leuprolide," "flutamide," "bicalutamide," "nilutamide," "fluoxymesterone," "estradiol," "octreotide," "megestrol," "medroxyprogesterone acetate," "enzalutamide," and "abiraterone" were searched.

RESULTS

Data from 19,430 patients in 35 clinical trials were available for analysis. Of these, 13,415 patients had received endocrine treatments and 6,015 patients served as controls. The incidence of all-grade alopecia ranged from 0% to 25%, with an overall incidence of 4.4% (95% confidence interval: 3.3%-5.9%). The highest incidence of all-grade alopecia was observed in patients treated with tamoxifen in a phase II trial (25.4%); similarly, the overall incidence of grade 2 alopecia by meta-analysis was highest with tamoxifen (6.4%). The overall relative risk of alopecia in comparison with placebo was 12.88 (p < .001), with selective estrogen receptor modulators having the highest risk.

CONCLUSION

Alopecia is a common yet underreported adverse event of endocrine-based cancer therapies. Their long-term use heightens the importance of this condition on patients' quality of life. These findings are critical for pretherapy counseling, the identification of risk factors, and the development of interventions that could enhance adherence and mitigate this psychosocially difficult event.

Effects of femara and tamoxifen on proliferation of FM3A cells in culture

In this study, antiproliferative effects of the selective estrogen receptor modulator Tamoxifen and the aromatase inhibitor letrozole (Femara) were evaluated and compared using the FM3A cell line, originating from a C3H mouse mammary carcinoma and positive in terms of estrogen receptor (ER) expression. Cell kinetic parameters including labelling index, mitotic index and labelling index were assessed after exposure of the. FM3A cell line to 0.001μg/ml of Tamoxifen and 0.25μg/ml of Femara for 4, 8, 16 and 32 h for all parameters. The results showed that cell growth was inhibited by both agents. There was a significant decrease in labelling index and mitotic index and significant increase in apoptotic index for all experimental groups. The differences between control and all experimental groups were statistically significant (p<0.001) for all applications.

A randomized trial to assess the biological activity of short-term (pre-surgical) fulvestrant 500 mg plus anastrozole versus fulvestrant 500 mg alone or anastrozole alone on primary breast cancer

INTRODUCTION

Fulvestrant shows dose-dependent biological activity. Greater estrogen-receptor (ER) blockade may feasibly be achieved by combining fulvestrant with anastrozole. This pre-surgical study compared fulvestrant plus anastrozole versus either agent alone in patients with ER-positive breast cancer.

METHODS

In this double-blind, multicenter trial, 121 patients received fulvestrant 500 mg on Day 1 plus anastrozole 1 mg/day for 14 to 21 days (F + A); fulvestrant plus anastrozole placebo (F); or fulvestrant placebo plus anastrozole (A), 2 to 3 weeks before surgery. ER, progesterone-receptor (PgR) and Ki67 expression were determined from tumor biopsies before treatment and at surgery.

RESULTS

A total of 103 paired samples were available (F, n = 35; F+A, n = 31; A, n = 37). All treatments significantly reduced mean ER expression from baseline (F: -41%, P = 0.0001; F + A: -39%, P = 0.0001; A: -13%, P = 0.0034). F and F + A led to greater reductions in ER versus A (both P = 0.0001); F + A did not lead to additional reductions versus F. PgR and Ki67 expression were significantly reduced with all treatments (means were -34% to -45%, and -75% to -85%, respectively; all P = 0.0001), with no differences between groups.

CONCLUSIONS

In this short-term study, all treatments reduced ER expression, although F and F + A showed greater reductions than A. No significant differences were detected between the treatment groups in terms of PgR and Ki67 expression. No additional reduction in tumor biomarkers with combination treatment was observed, suggesting that F + A is unlikely to have further clinical benefit over F alone.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00259090.

Ganitumab with either exemestane or fulvestrant for postmenopausal women with advanced, hormone-receptor-positive breast cancer: a randomised, controlled, double-blind, phase 2 trial

BACKGROUND

Insulin-like growth factors (IGF-1 and IGF-2) bind to the IGF-1 receptor (IGF-1R), increasing cell proliferation and survival. Ganitumab is a monoclonal IgG1 antibody that blocks IGF-1R. We tested the efficacy and safety of adding ganitumab to endocrine treatment for patients with hormone-receptor-positive breast cancer.

METHODS

We did this phase 2 trial in outpatient clinics and hospitals. We enrolled postmenopausal women with hormone-receptor-positive, locally advanced or metastatic breast cancer previously treated with endocrine treatment. They were randomly assigned (2:1) with a central randomisation schedule to receive intravenous ganitumab 12 mg per kg bodyweight or placebo in combination with open-label intramuscular fulvestrant (500 mg on day 1, then 250 mg on days 15, 29, and every 28 days) or oral exemestane (25 mg once daily) on a 28-day cycle. Patients, investigators, study monitors, and the sponsor staff were masked to treatment allocation. Response was assessed every 8 weeks. The primary endpoint was median progression-free survival in the intention-to-treat population. We analysed overall survival as one of our secondary endpoints. The study is registered at ClinicalTrials.gov, number NCT00626106.

FINDINGS

We screened 189 patients and enrolled 156 (106 in the ganitumab group and 50 in the placebo group). Median progression-free survival did not differ significantly between the ganitumab and placebo groups (3·9 months, 80% CI 3·6-5·3 vs 5·7 months, 4·4-7·4; hazard ratio [HR] 1·17, 80% CI 0·91-1·50; p=0·44). However, overall survival was worse in the the ganitumab group than in the placebo group (HR 1·78, 80% CI 1·27-2·50; p=0·025). With the exception of hyperglycaemia, adverse events were generally similar between groups. The most common grade 3 or higher adverse event was neutropenia-reported by six of 106 (6%) patients in the ganitumab group and one of 49 (2%) in the placebo group. Hyperglycaemia was reported by 12 of 106 (11%) patients in the ganitumab group (with six patients having grade 3 or 4 hyperglycaemia) and none of 49 in the placebo group. Serious adverse events were reported by 27 of 106 (25%) patients in the ganitumab group and nine of 49 (18%) patients in the placebo group.

INTERPRETATION

Addition of ganitumab to endocrine treatment in women with previously treated hormone-receptor-positive locally advanced or metastatic breast cancer did not improve outcomes. Our results do not support further study of ganitumab in this subgroup of patients.

FUNDING

Amgen.

Treatment algorithms for hormone receptor-positive advanced breast cancer: applying the results from recent clinical trials into daily practice—insights, limitations, and moving forward

Hormone receptor-positive (HR+) breast cancer is the most prevalent subtype of breast cancer in both early- and advanced-stage disease. Thus, the treatment of HR+ breast cancer has had the greatest global influence in improving clinical outcomes overall. Although the first-line metastatic breast cancer (MBC) trials comparing a third-generation aromatase inhibitor (AI) to tamoxifen have favored the AI, one of the challenges in translating these findings into clinical practice stems from the influence of prior adjuvant endocrine therapy, particularly the increasing use of adjuvant AIs today, on the choice of endocrine agent in the advanced setting because of the development of acquired resistance. Because the majority of patients enrolled into these studies were either endocrine-treatment naïve or exposed to tamoxifen only, the "real-life" applicability of the evidence is unclear. Because a superior dose of the selective estrogen receptor (ER) downregulator fulvestrant has now been established, its role as first-line therapy is being re-established. We are now starting to see the promise realized with blocking cross-talking growth factor pathways in addition to the ER pathway. The greatest efficacy is seen with the mammalian target of rapamycin (mTOR) inhibitor everolimus in combination with exemestane and, perhaps to a lesser extent, anti-HER2-directed therapy in combination with an AI. Future gains will likely involve a greater understanding of the redundancy and compensation induced by blocking these pathways, trials involving blocking multiple pathways in addition to hormonal agents, and the molecular interrogation of the individual's tumor in search of predictive biomarkers and "actionable" genomic aberrations.

Systematic review of lapatinib in combination with letrozole compared with other first-line treatments for hormone receptor positive(HR+) and HER2+ advanced or metastatic breast cancer(MBC)

BACKGROUND

Third-generation aromatase inhibitors (letrozole, anastrozole) have shown superior efficacy in early and advanced breast cancer compared with tamoxifen. For HR+, HER2+ MBC, combination of an AI with an anti-HER2 agent (lapatinib or trastuzumab) has shown clinical benefit.

METHODS

Six databases were searched until January 2009 for randomized controlled clinical trials, assessing the safety and efficacy of first-line treatments for postmenopausal women with HR+ and HER2 (ErbB2) positive MBC, who have not received prior therapy for advanced or metastatic disease. Relevant interventions were lapatinib, aromatase inhibitors, tamoxifen, and trastuzumab. Outcomes included overall survival (OS), progression-free-survival (PFS), time-to-progression (TTP), and objective response rate (ORR).

RESULTS

Eighteen studies (62 papers) were included. Lapatinib + letrozole was significantly superior to letrozole alone based on a direct head-to-head study in terms of PFS/TTP and ORR. Using a network meta-analysis, compared with lapatinib + letrozole, tamoxifen (HR = 0.45 (95% CI: 0.32, 0.65) and anastrozole (HR = 0.53 (0.36, 0.80)) scored significantly worse in terms of PFS/TTP and ORR (tamoxifen: OR = 0.25 (0.12, 0.53), anastrozole: OR = 0.27 (0.12, 0.58). The combination also seemed significantly superior to exemestane in terms of PFS/TTP (HR = 0.52 (0.34, 0.79)). Lapatinib + letrozole also seemed better, although not significantly, in terms of OS versus tamoxifen: HR = 0.74 (0.49, 1.12), anastrozole: HR = 0.71 (0.45, 1.14) and exemestane: HR = 0.65 (0.39, 1.11). When compared with trastuzumab + anastrozole, lapatinib + letrozole seemed to be better in terms of OS (HR = 0.85 (0.47, 1.54)), PFS/TTP (HR = 0.89 (0.54, 1.47)) and ORR (OR = 0.92 (0.24, 3.48)), although, none of these results were significant.

DISCUSSION

Lapatinib + letrozole was significantly superior to letrozole in terms of PFS/TTP and ORR based on a direct head-to-head study. Indirect comparisons appeared to favor lapatinib + letrozole versus other first-line treatments used in this patient population in terms of three main outcomes: OS, PFS/TTP and ORR. Indirect comparison results are based on a network analysis for which the basic assumptions of homogeneity, similarity and consistency were not fulfilled. Therefore, despite the fact that these are the best available data, the results need to be interpreted with caution.

mTOR inhibitors in the management of hormone receptor-positive breast cancer: the latest evidence and future directions

BACKGROUND

There is an unmet therapeutic need in endocrine-resistant, hormone receptor (HR)-positive, human epidermal growth factor receptor 2-negative advanced breast cancer (BC). Preclinical studies support the hypothesis that the mammalian target of rapamycin (mTOR) inhibition could potentially overcome resistance to endocrine therapy.

MATERIALS AND METHODS

A literature review regarding BC and mTOR inhibitors was undertaken. The reference lists from retrieved manuscripts were reviewed to identify further studies.

RESULTS

Phase II studies have reported that the combination of mTOR inhibitors with endocrine therapy shows efficacy in patients with advanced disease that progressed after treatment with aromatase inhibitors. The recent findings of the phase III BOLERO-2 confirmed that everolimus in combination with exemestane significantly improved progression-free survival and response rate, with a manageable safety profile.

CONCLUSIONS

The addition of everolimus to exemestane for women with HR-positive metastatic BC is now considered a new therapeutic strategy. However, a word of caution should be added regarding toxic effects, which might limit practical use and compliance. It is essential that clinicians are educated about key recommendations for toxicity management and specific guideline dose modifications. Additional research efforts with the addition of these compounds in the early-stage setting is greatly needed to improve the survival of patients with HR-positive BC.

Clinical profiles predict early nonadherence to adjuvant endocrine treatment in a prospective breast cancer cohort

Nonadherence to adjuvant endocrine breast cancer treatment adversely affects disease-free and overall survival. Clinical predictors of nonadherence may allow for specific interventions to reduce nonadherence and improve survival. The aim was to investigate whether clinical characteristics predict nonadherence. Clinical characteristics and information on adherence were obtained from 417 patients with breast cancer in a population-based prospective cohort from southern Sweden using patient charts, pathology reports, and questionnaires filled out at the 1- and 2-year follow-up visits. At the 1- and 2-year follow-up visits, 36 (8.6%) and 33 (9.7%) patients were nonadherent, respectively. Thirteen of the nonadherent patients declined treatment and were never prescribed endocrine treatment. A body mass index (BMI) < 25 kg/m(2), preoperative current smoking, and drinking alcohol less often than twice a month predicted nonadherence at the 1-year [relative risk (RR), 5.24; 95% confidence interval (CI), 2.75-9.97] and the 2-year visits (RR, 4.07; 95% CI, 2.11-7.84) in patients with at least two of these clinical characteristics. When low histologic grade (I) was added to the model, having at least two of these four clinical characteristics predicted nonadherence at the 1-year (RR, 4.94; 95% CI, 2.46-10.00) and the 2-year visits (RR, 4.74; 95% CI, 2.28-9.87), the two profiles had a sensitivity ranging from 60.6% to 72.7%, whereas the specificity ranged from 68.0% to 78.4%. Nonadherence at the 1-year visit was associated with an increased risk for early breast cancer events (HR, 2.97; 95% CI, 1.08-8.15), adjusted for age and tumor characteristics. In conclusion, two clinical profiles predicted early nonadherence and may allow for targeted interventions to increase adherence if validated in an independent cohort.

Impact of the introduction of government use licenses on the drug expenditure on seven medicines in Thailand

OBJECTIVES

To assess the budget impact of the government use licenses policy, a form of compulsory licensing used by the government, on seven patented drugs, namely, efavirenz, lopinavir/ritonavir combination, clopidogrel, letrozole, docetaxel, erlotinib, and imatinib, in Thailand between 2006 and 2008.

METHODS

By using government's perspective, budget impact was estimated within a 5-year period after the introduction of the policy. The number of patients who need treatment with each drug and the costs of treatments by both original and generic versions were obtained from Thai government agencies. Probabilistic sensitivity analysis was used to determine the impact of uncertainty surrounding parameters such as the numbers of patients and the health-care costs.

RESULTS

The study indicated that the use of generic drugs under the policy could save the government budget approximately $370 million over 5 years. It was also found that each drug had a different effect on budget saving depending on the number of patients treated, the difference in drug costs between original and generic drugs, and the lag time from the introduction of the policy to the availability of the generic drugs on the market.

CONCLUSION

The study showed that the introduction of the government use licenses policy in Thailand would provide significant benefits for the study timeframe; however, there are several issues that should be taken into account when the government use licenses policy is adopted.

A shift in the treatment of hormone receptor and human epidermal growth factor receptor 2-positive metastatic breast cancer

Historically, postmenopausal women with estrogen receptor (ER)-positive metastatic breast cancer (MBC) with a long disease-free interval and small volume disease have received an aromatase inhibitor. However, the advent of human epidermal growth factor receptor 2 (HER2) testing and its recognition as a poor prognostic indicator has led to the first line use of anti-HER2 directed therapy in combination with chemotherapy. The optimal treatment for those who are both hormone receptor and HER2 receptor positive is less clear. Tumors rich in ER are considered to be less responsive to chemotherapy, and hormone therapy has the benefit of being less toxic than chemotherapy. However, preclinical evidence suggests that HER2 overexpression may confer resistance to endocrine therapy, even in the presence of hormone receptors, due to crosstalk between the two pathways. This review summarizes the evidence from three clinical trials for combining endocrine therapy with anti-HER2 therapy in MBC. The trials raise the possibility of a new treatment approach to co-positive tumors in patients with good performance status and low tumor burden, and a means to potentially delay the need for chemotherapy.

Systematic review of aromatase inhibitors in the first-line treatment for hormone sensitive advanced or metastatic breast cancer

To undertake a systematic review of three first-line treatments (letrozole, anastrozole and exemestane) for hormone sensitive advanced or metastatic breast cancer (MBC) in post-menopausal women. We searched six databases from inception up to January 2009 for relevant trials regardless of language or publication status. Randomised controlled clinical trials assessing the safety and efficacy of first-line AIs for post-menopausal women with hormone receptor-positive (HR+, i.e. ER+ and/or PgR+) with or without ErbB2 (HER2)-positive MBC, who have not received prior therapy for advanced or metastatic disease were included. Where meta-analysis using direct or indirect comparisons was considered unsuitable for some or all of the data, we employed a narrative synthesis method. Four studies (25 papers) met the inclusion criteria. From the available evidence, it was possible to directly compare the three AIs with tamoxifen. In addition, by using a network meta-analysis it was possible to compare the three AIs with each other. Based on direct evidence, letrozole seemed to be significantly better than tamoxifen in terms of time-to-progression (TTP) (HR = 0.70 (95% CI: 0.60, 0.82)), objective response rate (RR = 0.65 (95% CI: 0.52, 0.82)) and quality-adjusted time without symptoms or toxicity (Q-Twist difference = 1.5; P < 0.001). Exemestane seemed significantly superior to tamoxifen in terms of objective response rate (RR = 0.68 (95% CI: 0.53, 0.89)). Anastrozole seemed significantly superior to tamoxifen in terms of TTP in one trial (HR = 1.42 (95% CI: 1.15, NR)), but not in the other (HR = 1.01 (95% CI: 0.87, NR)). In terms of adverse events, no significant differences were found between letrozole and tamoxifen. Tamoxifen was associated with significantly more serious adverse events in comparison with exemestane (OR = 0.61 (95% CI: 0.38, 0.97)); while exemestane was associated with significantly more arthralgia in comparison with tamoxifen (OR = 2.33 (95% CI: 1.07, 5.11)). Anastrozole was associated with significantly more total adverse events (OR = 1.04 (95% CI: 1.00, 1.09)) and hot flushes (OR = 1.39 (95% CI: 1.03, 1.89)) in comparison with tamoxifen in one trial; however, the other trial showed no significant differences in adverse events between anastrozole and tamoxifen. The indirect comparison of AIs with each other in women with post-menopausal, hormone sensitive advanced or MBC showed that letrozole and exemestane were better in terms of objective response rate than anastrozole; while the more clinically relevant outcomes overall survival (OS) and progression-free survival (PFS) showed no significant differences between AIs. OS and PFS showed no significant differences between AIs and hence based on these results a class effect for all AIs is possible. However, these results are based on indirect comparisons and a network analysis for which the basic assumptions of homogeneity, similarity and consistency were not fulfilled. Therefore, despite the fact that these are the best available data, the results need to be interpreted with appropriate caution. Head-to-head comparisons between letrozole, anastrozole and exemestane in the first-line MBC setting are warranted.

Letrozole

IMPORTANCE OF THE FIELD

Aromatase is an enzyme which converts adrenal androgens to estrogens in postmenopausal women. Given the importance of estrogens in breast cancer growth, aromatase inhibitors are used to treat breast cancer in different settings. This review focuses on letrozole, a third generation aromatase inhibitor, encompassing pharmacodynamic and pharmacokinetic aspects as well as its clinical efficacy and safety.

AREAS COVERED IN THIS REVIEW

A literature search and review of the studies published on letrozole were carried out using the MEDLINE database up to November 2009.

WHAT THE READER WILL GAIN

The paper provides the reader with information about pharmacodynamic and pharmacokinetic aspects of letrozole, its preclinical and clinical efficacy and its safety.

TAKE HOME MESSAGE

Letrozole is a well-tolerated and effective drug in metastatic breast cancer in postmenopausal women. Two clinical trials conducted in early breast cancer have confirmed its role in the adjuvant setting in postmenopausal women. More recently, data have confirmed its efficacy as neoadjuvant treatment in breast cancer. Future developments include the combination of letrozole with new biologic agents and tailoring of treatment with gene expression profiling studies.

Aromatase inhibitors for treatment of advanced breast cancer in postmenopausal women

BACKGROUND

Endocrine therapy removes the influence of oestrogen on breast cancer cells and so hormonal treatments such as tamoxifen, megestrol acetate and medroxyprogesterone acetate have been in use for many years for advanced breast cancer. Aromatase inhibitors (AIs) inhibit oestrogen synthesis in the peripheral tissues and have a similar tumour-regressing effect to other endocrine treatments. Aminoglutethimide was the first AI in clinical use and now the third generation AIs, anastrozole, exemestane and letrozole, are in current use. Randomised trial evidence on response rates and side effects of these drugs is still limited.

OBJECTIVES

To compare AIs to other endocrine therapy in the treatment of advanced breast cancer in postmenopausal women.

SEARCH STRATEGY

For this update, the Cochrane Breast Cancer Group Specialised Register and the Cochrane Central Register of Controlled Trials (CENTRAL) and relevant conference proceedings were searched (to 30 June 2008).

SELECTION CRITERIA

Randomised controlled trials in postmenopausal women comparing the effects of any AI versus other endocrine therapy, no endocrine therapy, or a different AI in the treatment of advanced (metastatic) breast cancer. Non-English language publications, comparisons of the same AI at different doses, AIs used as neoadjuvant treatment, or outcomes not related to tumour response were excluded.

DATA COLLECTION AND ANALYSIS

Data from published trials were extracted independently by two review authors and cross-checked by a third. Hazard ratios (HR) were derived for analysis of time-to-event outcomes (overall and progression-free survival). Odds ratios (OR) were derived for objective response, clinical benefit, and toxicity.

MAIN RESULTS

Thirty-seven trials were identified, 31 of which were included in the main analysis of any AI versus any other treatment (11,403 women). No trials were excluded due to inadequate allocation concealment. The pooled estimate showed a significant survival benefit for treatment with an AI over other endocrine therapies (HR 0.90, 95% CI 0.84 to 0.97). A subgroup analysis of the three commonly prescribed AIs (anastrozole, exemestane, letrozole) also showed a similar survival benefit (HR 0.88, 95% CI 0.80 to 0.96). There were very limited data to compare one AI with a different AI, but these suggested an advantage for letrozole over anastrozole.AIs have a different toxicity profile to other endocrine therapies. For those currently prescribed, and for all AIs combined, they had similar levels of hot flushes and arthralgia; increased risks of rash, nausea, diarrhoea and vomiting; but a 71% decreased risk of vaginal bleeding and 47% decrease in thromboembolic events compared with other endocrine therapies.

AUTHORS' CONCLUSIONS

In women with advanced (metastatic) breast cancer, aromatase inhibitors including those in current clinical use show a survival benefit when compared to other endocrine therapy.

Endocrine therapy of metastatic breast cancer

Breast cancer growth and dissemination is regulated by estrogen and different growth factor receptor signalling pathways. The increasing knowledge of the biology of breast cancer regarding the interaction of these signalling pathways provides a tool to understand endocrine therapies response and resistance mechanisms. In patients with slowly progressive disease, no visceral involvement, and minimal symptoms, endocrine therapy could be the strategy of choice, even if the tumor has low estrogen receptor expression. Ovarian suppression and tamoxifen are recommended for premenopausal patients whether aromatase inhibitors are the option for postmenopausal ones. Chemotherapy still remains as the right alternative for hormone unresponsive or resistant patients. This is a review focused on the different strategies and combinations of endocrine therapies for metastatic breast cancer patients considering the potential strategies clinically tested to overcome resistance and the different treatments of choice available for each scenario of disseminated disease.