Incidence and time course of everolimus-related adverse events in postmenopausal women with hormone receptor-positive advanced breast cancer: insights from BOLERO-2

Breast cancer treatment-induced cardiotoxicity

INTRODUCTION

Breast cancer is the most frequent cancer affecting women worldwide. In every setting, the majority of women are treated with an evergrowing arsenal of therapeutic agents that have greatly improved their outcomes. However, these therapies can also be associated with significant adverse events. Areas covered: This review aims to thoroughly describe the current state of the evidence regarding the potential cardiotoxicity of agents commonly used in the treatment of breast cancer. These include chemotherapeutic agents, anti-HER2 therapies and CDK4/6 and mTOR inhibitors. Furthermore, issues related to the risk stratification and monitoring tools are explored. Expert opinion: Anthracycline- and trastuzumab-related cardiac toxicities have been extensively studied. Substantial evidence is now available concerning additional anti-HER2 agents such as pertuzumab, T-DM1 and tyrosine kinase inhibitors; overall, the cardiotoxicity profile is reassuring. Cardiac events due to endocrine therapy are mostly ischemic and, in the context of prolonged therapy, need specific attention. Novel agents implicated in the treatment of hormone receptor-positive disease are potentially arrhythmogenic and the exact risk will need to be further refined. As for today, assessment of baseline risk factors prior to treatment initiation and cardiac imaging before and during treatment remains the optimal way to prevent cardiac dysfunction. Cardioprotective therapy in primary prevention is still a matter of debate.

Advances in the treatment of advanced oestrogen-receptor-positive breast cancer

Oestrogen-receptor-positive breast cancer is the most common subtype of breast cancer. Endocrine therapies that target the dependence of this subtype on the oestrogen receptor have substantial activity, yet the development of resistance to therapy is inevitable in advanced cancer. Major progress has been made in identifying the drivers of oestrogen-receptor-positive breast cancer and the mechanisms of resistance to endocrine therapy. This progress has translated into major advances in the treatment of advanced breast cancer, with several targeted therapies that enhance the efficacy of endocrine therapy; inhibitors of mTOR and inhibitors of the cyclin-dependent kinases CDK4 and CDK6 substantially improve progression-free survival. A new wave of targeted therapies is being developed, including inhibitors of PI3K, AKT, and HER2, and a new generation of oestrogen-receptor degraders. Considerable challenges remain in patient selection, deciding on the most appropriate order in which to administer therapies, and establishing whether cross-resistance occurs between therapies.

New Frontiers in the Pathobiology and Treatment of Cancer Regimen-Related Mucosal Injury

Mucositis is a common complication of chemotherapy, radiotherapy and targeted agents. It often affects compliance to anticancer therapies as it frequently causes schedule delays, interruptions or discontinuations of treatment. Moreover, the economic impact related to the management of mucositis is topical and several estimations of additional hospital costs due to this clinical condition have been recently reported. The ability to determine risk factors for mucositis, to early detect its onset, to assess correctly the degree of this toxicity and to plan its multidisciplinary management are all key elements to guarantee the quality of life of patients and to avoid useless dose reduction or interruption of treatment. The pathogenesis of mucositis is multifactorial and it is classily subdivided into oral and gastrointestinal mucositis according to its anatomic presentation. Treatment and patients’ related factors might help in predicting the frequency and the potential degree of symptoms onset. Here we discuss about clinical presentation and pathogenesis of mucositis in relation to different kinds of treatments. Moreover, we focus on therapeutic and prevention strategies, describing past and present management according to international guidelines and the most promising new data about agents potentially able to further improve the treatment of mucositis in the next future.

Dose intensity and efficacy of the combination of everolimus and exemestane (EVE/EXE) in a real-world population of hormone receptor-positive (ER+/PgR+), HER2-negative advanced breast cancer (ABC) patients: a multicenter Italian experience

AIM

This retrospective analysis focused on the effect of treatment with EVE/EXE in a real-world population outside of clinical trials. We examined the efficacy of this combination in terms of PFS and RR related to dose intensity (5 mg daily versus 10 mg daily) and tolerability.

METHODS

163 HER2-negative ER+/PgR+ ABC patients, treated with EVE/EXE from May 2011 to March 2016, were included in the analysis. The primary endpoints were the correlation between the daily dose and RR and PFS, as well as an evaluation of the tolerability of the combination. Secondary endpoints were RR, PFS, and OS according to the line of treatment. Patients were classified into three different groups, each with a different dose intensity of everolimus (A, B, C).

RESULTS

RR was 29.8% (A), 27.8% (B) (p = 0.953), and not evaluable (C). PFS was 9 months (95% CI 7-11) (A), 10 months (95% CI 9-11) (B), and 5 months (95% CI 2-8) (C), p = 0.956. OS was 38 months (95% CI 24-38) (A), median not reached (B), and 13 months (95% CI 10-25) (C), p = 0.002. Adverse events were stomatitis 57.7% (11.0% grade 3-4), asthenia 46.0% (6.1% grade 3-4), hypercholesterolemia 46.0% (0.6% grade 3-4), and hyperglycemia 35.6% (5.5% grade 3-4). The main reason for discontinuation/interruption was grade 2-3 stomatitis.

CONCLUSIONS

No correlation was found between dose intensity (5 vs. 10 mg labeled dose) and efficacy in terms of RR and PFS. The tolerability of the higher dose was poor in our experience, although this had no impact on efficacy.

Towards therapeutic drug monitoring of everolimus in cancer? Results of an exploratory study of exposure-effect relationship

INTRODUCTION

Therapeutic drug monitoring (TDM) of everolimus is not performed in oncology and no trough level (C₀) target has been yet defined. The aim of this study was to determine everolimus C₀ target for toxicity and efficacy.

MATERIALS AND METHODS

Clinical, biological and radiologic data from 54 patients were collected. Toxicity event was defined by termination, temporary interruption and/or dose reduction of everolimus while efficacy was defined as progression-free survival. C₀ values were dichotomized by ROC curve analysis and the association between exposure and outcome was determined using Cox models for repeated events (toxicity) or Cox model censured at the first event (progression free survival).

RESULTS

Among the 42 patients (77.8%) with breast cancer, 10 (18.5%) kidney cancer and 2 (3.7%) neuroendocrine cancer, adverse events were reported in 75.9% of the patients (everolimus termination in 25.9% patients). C₀ everolimus higher than 26.3ng/mL (Sen=0.38,Spe=0.88) were associated with a 4-fold increased risk of toxicity (HR=4.12, IC95%=[1.48-11.5], p=0.0067) whereas C₀ lower than 11.9ng/mL were associated with a 3-fold increased risk of progression (HR=3.2, IC95%=[1.33-7.81],p=0.001).

DISCUSSION

Further studies are required to evaluate the everolimus C₀ threshold proposed for toxicity (26.3ng/mL) and for progression (11.9ng/mL) especially with a large number of patients and more homogeneous types of cancer. However, these results are in favour of TDM for everolimus in oncology.

Role of everolimus in the treatment of metastatic HER2-negative/HR-positive breast cancer

Metastatic breast cancer (mBC) is a leading cause of mortality for women around the world. The response to hormonotherapy of the patients with HER2-negative/HR-positive mBC is usually limited, and many strategies are in place to contrast the hormonotherapy resistance. Since efficacy and effectiveness of everolimus have been established by many trials, this review is aimed to give a structured synthesis to define the everolimus clinical role among the treatment options for mBC. Key aspects of everolimus dosing and safety profile, drawn up by relevant findings, are included, as well as the role of biomarkers to identify subgroups of mBC patients who may best benefit from everolimus treatment.

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.

Anti-tumor effects of everolimus and metformin are complementary and glucose-dependent in breast cancer cells

Background

Clinical efficacy of the mTOR inhibitor everolimus is limited in breast cancer and regularly leads to side-effects including hyperglycemia. The AMPK inhibitor and anti-diabetic drug metformin may counteract everolimus-induced hyperglycemia, as well as enhancing anti-cancer efficacy. We investigated the glucose-dependent growth-inhibitory properties of everolimus, metformin and the combination in breast cancer cell lines.

Methods

The breast cancer cell lines MCF-7, MDA-MB-231 and T47D were cultured in media containing 11 mM or 2.75 mM glucose with 21% or 1% oxygen. Everolimus and metformin treated cells were subjected to cytotoxicity and clonogenic assays, western blotting, FACS and metabolic measurements.

Results

Everolimus was less effective in MCF7 cells under low glucose conditions compared to high glucose conditions (IC₅₀ of >50 nM vs 29.1 ± 1.4 nM) in a short-term survival assay, while sensitivity of MDA-MB-231 and T47D cells to everolimus was lost under low glucose conditions. In contrast, metformin was more effective in low than in high glucose conditions in MCF7 (IC₅₀ of 1.8 ± 1.2 mM vs >5 mM) and MDA-MB231 cells (1.5 ± 1.3 mM vs 2.6 ± 1.2 mM). Metformin sensitivity of T47D cells was independent of glucose concentrations. Everolimus combined with metformin additively inhibited cell survival, clonogenicity, mTOR signaling activity and mitochondrial respiration. These effects were not the result of enhanced autophagy or apoptosis induction. Similar results were observed under hypoxic conditions.

Conclusion

Metformin-induced effects are additive to the anti-proliferative and colony inhibitory properties of everolimus through inhibition of mitochondrial respiration and mTOR signaling. These results warrant further in vivo investigation of everolimus combined with metformin as a putative anti-cancer therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3230-8) contains supplementary material, which is available to authorized users.

Efficacy and safety of everolimus in Chinese metastatic HR positive, HER2 negative breast cancer patients: a real-world retrospective study

Background

Everolimus combined with endocrine therapy has been proved to be effective among postmenopausal women with hormone receptor-positive human epidermal growth factor receptor-2 negative (HR+/HER2-) metastatic breast cancer (MBC). We aimed to evaluate the efficacy and safety of everolimus plus endocrine therapy in Chinese real-world practice for the first time, and investigate factors associated with efficacy.

Methods

Seventy-five HR+/HER2- MBC patients were included in this retrospective study who received everolimus plus endocrine therapy after progression on prior endocrine therapy in Fudan University Shanghai Cancer Center (FUSCC) between June 2013 and February 2016. Main outcome measures are progression free survival (PFS), overall survival (OS), objective response rate (ORR), clinical benefit rate (CBR) and safety profile.

Results

After a median follow up of 10.3 (range: 2.1-32.2) months, median PFS was 5.9 months (95%CI 4.6-7.2), and median OS was not reached. The CBR was 38.8% (95%CI, 26.8-50.8) and ORR was 9.0% (95%CI, 2.0-16.0). Most common all-grade adverse events were stomatitis (57.1%), fatigue (25.7%), infection (24.3%) and hyperglycemia (21.4%). The most common ≥3 grade adverse events were stomatitis (9.3 %) and thrombocytopenia (5.7%). No treatment-related death was documented during and one month after the drug administration.

Conclusions

The combination of everolimus and endocrine therapy proved to be effective in Chinese population. The safety profiles were similar to previous studies but incidences were lower. In conclusion, everolimus combined with endocrine therapy provides a reasonable option for Chinese HR+/HER2- metastatic breast cancer patients.

Oral mucosal changes induced by anticancer targeted therapies and immune checkpoint inhibitors

Development of biological targeted therapies and immune checkpoint inhibitors has redefined the treatment for many cancers; however, the increasing use of new protocols has led to physicians observing a new spectrum of toxicities. To date, oral adverse events induced by these new anticancer therapies have been mainly reported using nonspecific terminology ("stomatitis," "mucosal inflammation," "mucositis") and remain poorly characterized, with the exception of mammalian target of rapamycin (mTOR) inhibitor-associated stomatitis. Oral toxicities of targeted therapies often display very characteristic features which clearly differ from classic oral injuries observed with cytotoxic chemotherapy and/or radiotherapy. In addition, they frequently affect more than 20% of treated patients and can lead to a significant morbidity or permanent treatment discontinuation. Oral mucosal toxicities described in this review include mTOR inhibitor-associated stomatitis (mIAS); stomatitis, benign migratory glossitis, and osteonecrosis of the jaw associated with multi-targeted kinase inhibitors of the VEGF and PDGF receptors; mucositis induced by EGFR inhibitors (in monotherapy or in combination with head and neck radiotherapy and/or chemotherapy); hyperkeratotic lesions with BRAF inhibitors; pigmentary changes and lichenoid reactions secondary to imatinib; and more recent data on the "Osler-Weber-Rendu-like syndrome" described with the antibody-drug conjugate, TDM-1. Finally, we provide, to our knowledge, the first available structured data on oral toxicities induced by the new recently FDA- and EMA-approved monoclonal antibodies targeting PD-1. Clinical management of these targeted therapy-related oral changes is also discussed.

Stomatitis Associated With Use of mTOR Inhibitors: Implications for Patients With Invasive Breast Cancer

BACKGROUND

The mammalian target of rapamycin (mTOR) inhibitor everolimus is approved (in combination with exemestane) for the treatment of postmenopausal women with advanced hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer resistant to endocrine therapy. Stomatitis is among the most frequently reported dose-limiting adverse events associated with everolimus use, often requiring treatment interruption or dose reduction.

OBJECTIVES

This article aims to educate nurses on the identification and management of stomatitis associated with mTOR inhibitors in hormone receptor-positive advanced breast cancer and to assist nurses with additional management techniques to improve patient outcomes.

METHODS

An evaluation of the literature highlighting the incidence, identification, and management of stomatitis in cancer was performed with a particular focus on breast cancer. In addition, the experiences of the authors' cancer center on managing stomatitis are described.

FINDINGS

A growing body of clinical evidence shows the benefits of adding steroid-based mouth rinses to the treatment plan. Clinical experience provides additional insight into stomatitis preventive and management strategies for patients with breast cancer receiving treatment with everolimus.

Improving Response to Hormone Therapy in Breast Cancer: New Targets, New Therapeutic Options

The majority of breast cancer expresses the estrogen and or progesterone receptors (ER and PR). In tumors without concomitant HER2 amplification, hormone therapy is a major treatment option for all disease stages. Resistance to hormonal therapy is associated with disease recurrence and progression. Recent studies have identified a number of resistance mechanisms leading to estrogen-independent growth of hormone receptor-positive (HR+) breast cancer as a result of genetic and epigenetic alterations, which could be exploited as novel therapeutic targets. These include acquired mutations in ER-alpha (ESR1) in response to endocrine deprivation; constitutive activation of cyclin-dependent kinases (CDK) 4 and 6; cross talk between ER and growth factor receptor signaling such as HER family members, fibroblast growth factor receptor (FGFR) pathways, intracellular growth, and survival signals PI3K/Akt/mTOR; and epigenetic modifications by histone deacetylase (HDAC) as well as interactions with tumor microenvironment and host immune response. Inhibitors of these pathways are being developed to improve efficacy of hormonal therapy for treatment of both metastatic and early-stage disease. Two agents are currently approved in the United States for the treatment of metastatic HR+ breast cancer, including the mTOR inhibitor everolimus and the CDK4/6 inhibitor palbociclib. Management of toxicity is a critical aspect of treatment; the primary toxicity of everolimus is stomatitis (treated with topical steroids) and of palbociclib is neutropenia (treated with dose reduction/delay). Many agents are in clinical trials, primarily in combination with hormone therapy; novel combinations are under active investigation.

Safety, Efficacy, and Patient Acceptability of Everolimus in the Treatment of Breast Cancer

Everolimus combined with exemestane is an important treatment option for patients suffering from estrogen receptor-positive, human epidermal growth factor receptor 2-negative, advanced breast cancer (ABC) who have been previously treated with a nonsteroidal aromatase inhibitor (NSAI). After presentation of phase III registration trial BOLERO-2, several phase IIIb trials have been started to evaluate this regimen in a more real-world setting. Here, we review the efficacy and safety data published or presented at selected international meetings. These studies confirmed the outcome observed in the BOLERO-2 trial. Patient acceptance rate is also discussed by focusing on the permanent everolimus discontinuation rate in these trials. Factors influencing the safety profile are also reported, including the impact of age. The optimal sequence of combined therapy approaches associating targeted and endocrine therapy (ET) has yet to be determined as new treatment options such as cyclin-dependent kinase inhibitors become available. However, everolimus-exemestane remains an important treatment option with a major impact on progression-free survival (PFS) and an acceptable safety profile.

The Role of mTOR Inhibitors in the Treatment of Patients with Tuberous Sclerosis Complex: Evidence-based and Expert Opinions

Tuberous sclerosis complex (TSC) is a genetic disorder arising from mutations in the TSC1 or TSC2 genes. The resulting over-activation of the mammalian target of rapamycin (mTOR) signalling pathway leaves patients with TSC susceptible to the growth of non-malignant tumours in multiple organs. Previously, surgery was the main therapeutic option for TSC. However, pharmacological therapy with mTOR inhibitors such as everolimus and sirolimus is now emerging as an alternate approach. Everolimus and sirolimus have already been shown to be effective in treating subependymal giant cell astrocytoma (SEGA) and renal angiomyolipoma (AML), and everolimus is currently being evaluated in treating TSC-related epilepsy. In November 2013 a group of European experts convened to discuss the current options and practical considerations for treating various manifestations of TSC. This article provides evidence-based recommendations for the treatment of SEGA, TSC-related epilepsy and renal AML, with a focus on where mTOR inhibitor therapy may be considered alongside other treatment options. Safety considerations regarding mTOR inhibitor therapy are also reviewed. With evidence of beneficial effects in neurological and non-neurological TSC manifestations, mTOR inhibitors may represent a systemic treatment for TSC.

Enhancing Endocrine Therapy Combination Strategies for the Treatment of Postmenopausal HR+/HER2- Advanced Breast Cancer

Breast cancer (BC) is the most common malignancy in women worldwide, with approximately two-thirds having hormone receptor-positive (HR+) tumors. New endocrine therapy (ET) strategies include combining ET agents as well as adding inhibitors targeting growth factors, angiogenesis, the mechanistic target of rapamycin, phosphoinositide 3-kinase (PI3K), or cyclin-dependent kinase 4/6 to ET. Level 1 evidence supports use of fulvestrant plus anastrozole or palbociclib plus letrozole as first-line therapy for HR+/HER- advanced BC with special consideration for the former in ET-naïve patients, as well as everolimus plus exemestane or palbociclib plus fulvestrant as second-line therapy with special consideration in select first-line patients. Although the safety profiles of these combinations are generally predictable and manageable, both everolimus and palbociclib are associated with an increased risk of potentially serious or early-onset toxicities requiring individualized a priori adverse event risk stratification, earlier and more rigorous agent-specific monitoring, and patient education. Although each of these combinations improves progression-free survival, none with the exception of anastrazole plus fulvestrant have demonstrated improved overall survival. PI3K catalytic-α mutations assessed from circulating tumor DNA represent the first potentially viable serum biomarker for the selection of ET combinations, and new data demonstrate the feasibility of this minimally invasive technique as an alternative to traditional tissue analysis. Therapeutic ratios of select ET combinations support their use in first- and second-line settings, but optimal sequencing has yet to be determined.

THE ONCOLOGIST

2017;22:12-24 IMPLICATIONS FOR PRACTICE: Emerging data show that new endocrine therapy (ET) combinations can improve progression-free and overall survival outcomes in patients with hormone receptor-positive, HER2-negative (HR+/HER-) advanced breast cancer. Level 1 evidence supports consideration of dual ET regimens, particularly in ET-naïve patients, or palbociclib plus letrozole as first-line therapy, as well as the addition of mTOR or CDK4/6 inhibitors to established ET in the second-line setting and in select first-line patients. Some combinations are associated with increased risk of class-specific toxicities that will require individualized risk stratification, earlier and more rigorous agent-specific monitoring, and patient education. Recent data on a noninvasive biomarker assay that predicts response to a phosphoinositide 3-kinase inhibitor demonstrates the feasibility of this minimally invasive technique as an alternative to traditional tissue analysis.

Topical Application of a Galenical Formulation for the Management of Everolimus-Induced Mucositis in Patients with Metastatic Cancer: a Retrospective Study

INTRODUCTION

Stomatitis is a common and potentially dose-limiting adverse event of the mammalian target of rapamycin (mTOR) inhibitor therapy. To minimize dose reductions or treatment delays that may affect therapeutic outcomes, management includes patient education, pain management strategies, and drug treatment. The aim of this study was to evaluate the effectiveness of a topically-applied galenical preparation to minimize the impact of everolimus-associated oral mucositis in patients with advanced cancer.

METHODS

Patients receiving everolimus plus exemestane for advanced breast cancer or everolimus alone for advanced renal cancer were eligible for inclusion. All patients were advised on procedures to maintain good oral hygiene and directed to use a dexamethasone-containing galenical preparation at the first signs of mucositis. Questionnaires were administered at baseline, and after cycles one, two, and three to evaluate the presence, duration, and intensity of oral mucositis.

RESULTS

Of the 19 patients included in the study (mean age 66 years; 16% male), mucositis developed in 10.5%, 47.4%, and 52.6% of patients after the first, second, and third cycles of everolimus, respectively. The median time to development of mucositis was 18.0 days, and the median time to mucositis resolution was 30.0 days. After the first, second, and third cycles of therapy, 5.3%, 10.5%, and 10.5% of patients required interruption of everolimus therapy; however, no dosage reductions for mucositis were necessary.

CONCLUSIONS

Patient education and the provision of an effective galenical preparation can minimize the effect of mTOR inhibitor-related mucositis.

CE: A Review of Common Oral Treatments for Breast Cancer: Improving Patient Safety in Nononcology Settings

: Breast cancer patients are living longer with the disease than ever before. According to the National Cancer Institute, more than 3 million women in the United States are currently living with a breast cancer diagnosis, and many seek care in nononcology settings, whether for treatment, acute symptoms and complaints related to their cancer diagnosis, or unrelated concerns. Yet many nononcology providers are unfamiliar with the various oral agents used to treat breast cancer, and their possible adverse effects and drug interactions. It is imperative that all providers be aware of these agents and know when a patient is currently taking or has taken them. This article provides an overview of the most common oral treatments for breast cancer and discusses common adverse effects and management.

Diabetology and oncology meet in a network model: union is strength

Diabetes and cancer are increasingly common conditions, and the management of cancer patients with diabetes is often challenging. Diabetes in cancer patients poses several complex clinical issues, including which treatment is suitable to control hyperglycemia, how to better counteract glucocorticoid-induced hyperglycemia, and how to manage nutritional problems of cachectic patients and glucose variability linked to artificial nutrition. A key aspect to consider is the patients' position on the trajectory of the oncologic disease, both to establish which level of glycemic control should be pursued and to decide the most suitable antidiabetic treatment to recommend. Endocrinologists are rarely involved in the management of patients with advanced cancer. Furthermore, lack of guidelines results in a "trial-and-error" approach, often with suboptimal disease management. Lastly, cancer survivors represent a frequently underestimated category of patients at higher cardiometabolic risk. A practical solution for these challenges lies in the implementation of care networks based on a close partnership and ongoing communication between oncologists, endocrinologists, and nutritionists, placing the patient at the center of the care process. At the same time, universities and scientific societies should play a key role in promoting research into areas of intersection of oncology and endocrinology, in raising awareness of common possibilities of primary and secondary prevention of metabolic and oncologic diseases, as well as specific challenges of managing diabetes and cancer, and proper training of health workers, while also supporting the shared implementation of effective management strategies.

Safety analysis, association with response and previous treatments of everolimus and exemestane in 181 metastatic breast cancer patients: A multicenter Italian experience

PURPOSE

The everolimus and exemestane combination represents a treatment option for the endocrine sensitive metastatic breast cancer (MBC) patients. The toxicity profile reported in the Bolero 2 trial showed the feasibility in the selected patients. Few data are available for the unselected population.

METHODS

In order to evaluate the safety in the unselected population of the clinical practice and to evaluate a possible association of toxicities with previous treatments, clinical data from 181 consecutive patients were retrospectively collected.

RESULTS

Due to toxic events, everolimus dosage was reduced to 5 mg in 27% of patients. No association was found in the analysis between toxicity and number of prior therapies, neither between toxicity and response. In the multivariate analysis the previous exposure to anthracyclines for advanced disease represents the only predictive factor of developing grade ≥2 toxicity (OR = 2.85 CI 95% 1.07-7.59, p = 0.036).

CONCLUSIONS

The association of everolimus and exemestane has confirmed to be a safe and effective treatment for endocrine sensitive MBC patients even in routine clinical practice. The rate of treatment discontinuation due to toxicity is low and none association between previous number of treatments and response or between toxicity and response was found.

Over-treatment in metastatic breast cancer

Metastatic breast cancer is an incurable disease and the main goals of treatment are prolongation of survival and preservation/improvement of quality of life. Thus the main philosophy of treatment should be to use the least toxic methods, as long as they provide sufficient disease control. In ER-positive tumours this can be in many cases achieved by endocrine therapy; in HER2-positive cancers efficacy of backbone therapy can be enhanced by an anti-HER2 agent. In patients requiring chemotherapy, consecutive single agent regimen provide disease control of a duration at least comparable to multidrug regimen, at a cost of significantly lower toxicity and are a preferred strategy in the majority of cases. Available data demonstrate, however, that aggressive chemotherapy is still overused in many metastatic breast cancer patients. The objective of this manuscript is to critically review available data on treatment choices and sequence in metastatic breast cancer across all breast cancer subtypes in relation to possible overtreatment, including therapies which are not recommended by current guidelines or not even approved. Our aim is to provide guidance on applying these data to clinical practice, but also to describe various, often non-scientific factors influencing therapeutic decisions in an aim to identify areas requiring educational and possibly political actions.

Treatment challenges for community oncologists treating postmenopausal women with endocrine-resistant, hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer

Community-based oncologists are faced with challenges and opportunities when delivering quality patient care, including high patient volumes and diminished resources; however, there may be the potential to deliver increased patient education and subsequently improve outcomes. This review discusses the treatment of postmenopausal women with endocrine-resistant, hormone receptor-positive, human epidermal growth factor receptor 2- negative advanced breast cancer in order to illustrate considerations in the provision of pertinent quality education in the treatment of these patients and the management of therapy-related adverse events. An overview of endocrine-resistant breast cancer and subsequent treatment challenges is also provided. Approved treatment options for endocrine-resistant breast cancer include hormonal therapies and mammalian target of rapamycin inhibitors. Compounds under clinical investigation are also discussed.

Oral mucosal injury caused by mammalian target of rapamycin inhibitors: emerging perspectives on pathobiology and impact on clinical practice

In recent years oral mucosal injury has been increasingly recognized as an important toxicity associated with mammalian target of rapamycin (mTOR) inhibitors, including in patients with breast cancer who are receiving everolimus. This review addresses the state-of-the-science regarding mTOR inhibitor-associated stomatitis (mIAS), and delineates its clinical characteristics and management. Given the clinically impactful pain associated with mIAS, this review also specifically highlights new research focusing on the study of the molecular basis of pain. The incidence of mIAS varies widely (2-78%). As reported across multiple mTOR inhibitor clinical trials, grade 3/4 toxicity occurs in up to 9% of patients. Managing mTOR-associated oral lesions with topical oral, intralesional, and/or systemic steroids can be beneficial, in contrast to the lack of evidence supporting steroid treatment of oral mucositis caused by high-dose chemotherapy or radiation. However, steroid management is not uniformly efficacious in all patients receiving mTOR inhibitors. Furthermore, technology does not presently exist to permit clinicians to predict a priori which of their patients will develop these lesions. There thus remains a strategic need to define the pathobiology of mIAS, the molecular basis of pain, and risk prediction relative to development of the clinical lesion. This knowledge could lead to novel future interventions designed to more effectively prevent mIAS and improve pain management if clinically significant mIAS lesions develop.

Real-World Analysis of Medical Costs and Healthcare Resource Utilization in Elderly Women with HR+/HER2- Metastatic Breast Cancer Receiving Everolimus-Based Therapy or Chemotherapy

INTRODUCTION

The objective of this study was to analyze medical costs and healthcare resource utilization (HRU) associated with everolimus-based therapy or chemotherapy among elderly women with hormone-receptor-positive, human-epidermal-growth-factor-receptor-2-negative (HR+/HER2-) metastatic breast cancer (mBC).

METHODS

Elderly women (≥65 years) with HR+/HER2- mBC who failed a non-steroidal-aromatase-inhibitor and subsequently began a new line of treatment with everolimus-based therapy or chemotherapy for mBC (index therapy) during July 20, 2012 to March 31, 2014 were identified from two large commercial claims databases. All-cause, BC-, and adverse event (AE)-related medical costs (2014 USD), and all-cause and AE-related HRU per patient per month (PPPM) were compared between patients treated with everolimus-based therapy and chemotherapy across their first four lines of therapy for mBC. Adjusted costs and HRU differences were estimated by pooling all lines and using multivariable models adjusted for differences in patient characteristics.

RESULTS

In total, 925 elderly patients (mean age approximately 73 years) with HR+/HER2- mBC met the inclusion criteria; 230 received everolimus-based therapy (240 lines) and 737 received chemotherapy (939 lines). Compared with chemotherapy, everolimus-based therapy was associated with significantly lower total all-cause PPPM medical services costs (adjusted mean difference: $4007), driven by lower inpatient ($1994) and outpatient ($1402) costs; lower BC-related medical services costs ($3129), driven by both BC-related inpatient ($1883) and outpatient costs ($913); and lower AE-related medical services costs ($1873; all P < 0.01). Additionally, compared to patients treated with chemotherapy, patients treated with everolimus-based therapy had fewer all-cause outpatient visits (adjusted incidence rate ratio = 0.69), BC-related outpatient visits (0.66), other-medical-service visits (0.65), and AE-related HRU (0.59), which was driven by significantly fewer AE-related outpatient visits (0.56; all P < 0.01). Subgroup analyses comparing medical costs of everolimus-based therapy with capecitabine monotherapy showed consistent results overall.

CONCLUSION

This retrospective claims database analysis of elderly women with HR+/HER2- mBC in the United States showed that everolimus-based therapy was associated with significantly lower all-cause, BC-related, and AE-related medical services costs and less use of healthcare resources compared with chemotherapy.

FUNDING

Novartis.

Epithelial to mesenchymal transition is associated with rapamycin resistance

Rapamycin analogues have antitumor efficacy in several tumor types, however few patients demonstrate tumor regression. Thus, there is a pressing need for markers of intrinsic response/resistance and rational combination therapies. We hypothesized that epithelial-to-mesenchymal transition (EMT) confers rapamycin resistance. We found that the epithelial marker E-cadherin protein is higher in rapamycin sensitive (RS) cells and mesenchymal breast cancer cell lines selected by transcriptional EMT signatures are less sensitive to rapamycin. MCF7 cells, transfected with constitutively active mutant Snail, had increased rapamycin resistance (RR) compared to cells transfected with wild-type Snail. Conversely, we transfected two RR mesenchymal cell lines-ACHN and MDA-MB-231-with miR-200b/c or ZEB1 siRNA to promote mesenchymal-to-epithelial transition. This induced E-cadherin expression in both cell lines, and ACHN demonstrated a significant increase in RS. Treatment of ACHN and MDA-MB-231 with trametinib modulated EMT in ACHN cells in vitro. Treatment of MDA-MB-231 and ACHN xenografts with trametinib in combination with rapamycin resulted in significant growth inhibition in both but without an apparent effect on EMT. Future studies are needed to determine whether EMT status is predictive of sensitivity to rapalogs and to determine whether combination therapy with EMT modulating agents can enhance antitumor effects of PI3K/mTOR inhibitors.

Endocrine Therapy for Hormone Receptor-Positive Metastatic Breast Cancer: American Society of Clinical Oncology Guideline

PURPOSE

To develop recommendations about endocrine therapy for women with hormone receptor (HR) -positive metastatic breast cancer (MBC).

METHODS

The American Society of Clinical Oncology convened an Expert Panel to conduct a systematic review of evidence from 2008 through 2015 to create recommendations informed by that evidence. Outcomes of interest included sequencing of hormonal agents, hormonal agents compared with chemotherapy, targeted biologic therapy, and treatment of premenopausal women. This guideline puts forth recommendations for endocrine therapy as treatment for women with HR-positive MBC.

RECOMMENDATIONS

Sequential hormone therapy is the preferential treatment for most women with HR-positive MBC. Except in cases of immediately life-threatening disease, hormone therapy, alone or in combination, should be used as initial treatment. Patients whose tumors express any level of hormone receptors should be offered hormone therapy. Treatment recommendations should be based on type of adjuvant treatment, disease-free interval, and organ function. Tumor markers should not be the sole criteria for determining tumor progression; use of additional biomarkers remains experimental. Assessment of menopausal status is critical; ovarian suppression or ablation should be included in premenopausal women. For postmenopausal women, aromatase inhibitors (AIs) are the preferred first-line endocrine therapy, with or without the cyclin-dependent kinase inhibitor palbociclib. As second-line therapy, fulvestrant should be administered at 500 mg with a loading schedule and may be administered with palbociclib. The mammalian target of rapamycin inhibitor everolimus may be administered with exemestane to postmenopausal women with MBC whose disease progresses while receiving nonsteroidal AIs. Among patients with HR-positive, human epidermal growth factor receptor 2-positive MBC, human epidermal growth factor receptor 2-targeted therapy plus an AI can be effective for those who are not chemotherapy candidates.

The therapeutic potential of mTOR inhibitors in breast cancer

Rapamycin and modified rapamycins (rapalogs) have been used to prevent allograft rejection after organ transplant for over 15 years. The mechanistic target of rapamycin (mTOR) has been determined to be a key component of the mTORC1 complex which consists of the serine/threonine kinase TOR and at least five other proteins which are involved in regulating its activity. Some of the best characterized substrates of mTORC1 are proteins which are key kinases involved in the regulation of cell growth (e.g., p70S6K) and protein translation (e.g., 4E-BP1). These proteins may in some cases serve as indicators to sensitivity to rapamycin-related therapies. Dysregulation of mTORC1 activity frequently occurs due to mutations at, or amplifications of, upstream growth factor receptors (e.g., human epidermal growth factor receptor-2, HER2) as well as kinases (e.g., PI3K) and phosphatases (e.g., PTEN) critical in the regulation of cell growth. More recently, it has been shown that certain rapalogs may enhance the effectiveness of hormonal-based therapies for breast cancer patients who have become resistant to endocrine therapy. The combined treatment of certain rapalogs (e.g., everolimus) and aromatase inhibitors (e.g., exemestane) has been approved by the United States Food and Drug Administration (US FDA) and other drug regulatory agencies to treat estrogen receptor positive (ER+) breast cancer patients who have become resistant to hormonal-based therapies and have progressed. This review will summarize recent basic and clinical research in the area and evaluate potential novel therapeutic approaches.

Occurrence and characterization of everolimus adverse events during first and subsequent cycles in the treatment of metastatic breast cancer

PURPOSE

Endocrine therapy remains the standard therapy for patients with metastatic hormone receptor (HR)-positive breast cancer. The novel combination of everolimus and exemestane has been shown to prolong progression-free survival but with increased adverse events compared to exemestane alone. In this study, we aimed to describe the frequency and timing of everolimus dose reductions and/or interruptions due to adverse events.

METHODS

This is a single-center retrospective case series including all patients who received everolimus in combination with exemestane from May 1, 2012, through July 31, 2013. The primary objective was to determine the incidence of first-cycle interruptions or dose reductions with everolimus.

RESULTS

Forty-six patients were included in the analysis. First-cycle dose reductions or interruptions were observed in 21 (45.6 %) patients. The most common adverse events leading to dose reduction or interruption was stomatitis (57.1 %), fatigue (14.3 %), and diarrhea (14.3 %). The median time to dose reduction was 14 days, and the median duration of the interruption was 14 days. The median progression-free survival was 6.2 months, and the median time to treatment failure was 4.4 months.

CONCLUSIONS

In this case series, almost half of the patients treated with everolimus and exemestane required a dose reduction or interruption of everolimus during the first cycle of treatment. This early onset of adverse events requires thorough patient education and close clinical monitoring during the first 28 days of therapy.

Molecular Pathways: Increased Susceptibility to Infection Is a Complication of mTOR Inhibitor Use in Cancer Therapy

As one of the earliest examples of "chemical biology," the M: echanistic T: arget of R: apamycin (mTOR) protein and its chemical inhibitors have been extensively studied across a spectrum of physiologic and pathologic processes at the molecular, organismal, and patient population levels. There are several FDA-approved mTOR inhibitors (sirolimus, everolimus, and temsirolimus) with indications for cancer treatment and for prevention of solid organ rejection. Dozens of mTOR inhibitors are currently being evaluated in hundreds of ongoing clinical trials across a spectrum of diseases, including numerous cancer indications, autoimmune diseases, and a number of congenital disorders. As many of the approved and investigational indications for mTOR inhibitors require long-term treatment, the magnitude and incidence of particular side effects differ from those observed in shorter-term treatments. Here, we focus on the increased risk of infections in patients being treated with mTOR inhibitors. While increased infection rates might be expected from a class of drugs approved as posttransplant immunosuppressants, we review reports from clinical, mechanistic, and genetically engineered mouse model studies detailing a much more nuanced view of mTOR inhibitor drug action and target biology.

Current management of mTOR inhibitor-associated stomatitis

mTOR inhibitor-associated stomatitis (mIAS) is an adverse event associated with mTOR inhibitor treatment for advanced cancers. mIAS tends to occur within 2 weeks of treatment start and resolve within weeks of symptom onset. mIAS is usually mild in severity and often self-limiting. Nevertheless, inadequately controlled mIAS can negatively affect patient function and treatment adherence. This review summarizes efficacy and mIAS safety data of mTOR inhibitors, and discusses prevention and treatment of mIAS. Patient cases are used to illustrate important practice points. Although mIAS has been recognized as a cancer treatment-related adverse event only in the last decade, several clinical studies are ongoing. This raises the expectation that management of mIAS in the future will be guided by strong evidence.

Dosing and Safety Implications for Oncologists When Administering Everolimus to Patients With Hormone Receptor-Positive Breast Cancer

Aberrations in the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway are common abnormalities in breast cancer and are associated with the development of resistance to endocrine- and human epidermal growth factor receptor (HER)2-targeted therapies. Because of the significant improvement in progression-free survival for everolimus plus exemestane compared with exemestane plus placebo, everolimus, an mTOR inhibitor, was approved in the United States for the treatment of patients with hormone receptor-positive (HR+), HER-negative, advanced breast cancer whose disease had progressed while receiving letrozole or anastrozole. To provide optimal prevention and management strategies, it is crucial that clinicians are aware of the adverse events (AEs) associated with mTOR inhibition. Understanding the appropriate dose modifications will help reduce toxicity and improve drug tolerance, thus achieving the optimal benefit from everolimus. Analyses of data from the Breast Cancer Trials of Oral Everolimus 2 trial have shown that, despite a greater frequency of AEs in the everolimus plus exemestane treatment arm, the AEs were effectively managed with temporary dose reductions or interruptions. In some cases, the full dose of everolimus could be resumed. Despite a lower mean dose and duration of exposure in patients aged ≥ 70 versus < 70 years, everolimus plus exemestane was similarly efficacious, suggesting that appropriate dose reductions for toxicity will not adversely impact efficacy. Appropriate modification of the everolimus dose and dose delay according to the severity of AEs, with resumption of the optimal dose of everolimus when toxicity has improved, will positively affect patient outcomes in HR+ advanced breast cancer.

A phase I dose-escalation study to assess safety, tolerability, pharmacokinetics, and preliminary efficacy of the dual mTORC1/mTORC2 kinase inhibitor CC-223 in patients with advanced solid tumors or multiple myeloma

BACKGROUND

The mammalian target of rapamycin (mTOR) pathway is essential for tumor development, yet mTOR inhibitors have yielded modest results. This phase 1 study investigated the mTORC1/mTORC2 inhibitor CC-223 in patients with advanced cancer.

METHODS

Patients with advanced solid tumors or multiple myeloma received an initial dose of 7.5-60 mg of CC-223, followed by oral daily dosing in 28-day cycles until disease progression. The primary objective was to determine the safety, tolerability, nontolerated dosage, maximum tolerated dosage (MTD), and preliminary pharmacokinetic profile. Secondary objectives were to evaluate pharmacodynamic effects and to describe preliminary efficacy.

RESULTS

Twenty-eight patients were enrolled and received ≥1 dose of CC-223. The most common treatment-related grade 3 adverse events were hyperglycemia, fatigue, and rash. Four patients had dose-limiting toxicities, including hyperglycemia, rash, fatigue, and mucositis. Therefore, 45 mg/d was determined to be the MTD. The pharmacokinetics of CC-223 demonstrated a mean terminal half-life ranging from 4.86 to 5.64 hours and maximum observed plasma concentration ranging from 269 to 480 ng/mL in patients who received CC-223 ≥45 mg/d. Phosphorylation of mTORC1/mTORC2 pathway biomarkers in blood cells was inhibited by CC-223 ≥30 mg/d with an exposure-response relationship. Best responses included 1 partial response (breast cancer; response duration 220 days; 30-mg/d cohort), stable disease (8 patients across ≥15 mg/d cohorts; response duration range, 36-168 days), and progressive disease (12 patients). The disease control rate was 32%.

CONCLUSIONS

CC-223 was tolerable, with manageable toxicities. Preliminary antitumor activity, including tumor regression, and evidence of mTORC1/mTORC2 pathway inhibition were observed.

Everolimus-Based Therapy versus Chemotherapy among Patients with HR+/HER2- Metastatic Breast Cancer: Comparative Effectiveness from a Chart Review Study

Objective. To compare the real-world effectiveness of everolimus-based therapy and chemotherapy in postmenopausal women with hormone-receptor-positive/human-epidermal-growth-factor-receptor-2-negative (HR+/HER2−) metastatic breast cancer (mBC). Methods. This retrospective chart review examined a nationwide sample of postmenopausal HR+/HER2− mBC women in community-based oncology practices. Patients received everolimus-based therapy or chemotherapy for mBC between 07/01/2012 and 04/15/2013, after failure of a non-steroidal aromatase inhibitor. Overall survival (OS), progression-free survival (PFS), and time on treatment (TOT) were compared using Kaplan-Meier analysis and Cox proportional hazards models adjusting for line of therapy and baseline characteristics. Results. 234 and 137 patients received everolimus-based therapy and chemotherapy. Patients treated with everolimus-based therapy tended to have less aggressive mBC than patients treated with chemotherapy. Multivariate-adjusted Cox models showed that everolimus-based therapy was associated with significantly longer OS [hazard ratio (HR) = 0.37, 95% confidence interval (CI): 0.22–0.63], PFS (HR = 0.70, 95% CI = 0.50–0.97), and TOT (HR = 0.34, 95% CI: 0.25–0.45) than chemotherapy. Adjusted comparative effectiveness results were generally consistent across lines of therapy. Conclusion. In this retrospective chart review of postmenopausal HR+/HER2− mBC patients, treatment with everolimus-based therapy was associated with longer OS, PFS, and TOT than chemotherapy.

Combination of everolimus with trastuzumab plus paclitaxel as first-line treatment for patients with HER2-positive advanced breast cancer (BOLERO-1): a phase 3, randomised, double-blind, multicentre trial

BACKGROUND

mTOR inhibition reverses trastuzumab resistance via the hyperactivated PIK/AKT/mTOR pathway due to PTEN loss, by sensitising PTEN-deficient tumours to trastuzumab. The BOLERO-1 study assessed the efficacy and safety of adding everolimus to trastuzumab and paclitaxel as first-line treatment for patients with HER2-positive advanced breast cancer.

METHODS

In this phase 3, randomised, double-blind trial, patients were enrolled across 141 sites in 28 countries. Eligible patients were aged 18 years or older, with locally assessed HER2-positive advanced breast cancer, with Eastern Cooperative Oncology Group (ECOG) performance status of 0-1, who had not received previous trastuzumab or chemotherapy for advanced breast cancer within 12 months of randomisation, had measurable disease as per Response Evaluation Criteria in Solid Tumors (RECIST) or bone lesions in the absence of measurable disease, without previous systemic treatment for advanced disease except endocrine therapy. Patients were randomly assigned (2:1) with an interactive voice and web response system to receive either 10 mg everolimus once a day orally or placebo plus weekly trastuzumab intravenously at 4 mg/kg loading dose on day 1 with subsequent weekly doses of 2 mg/kg of each 4 week cycle plus paclitaxel intravenously at a dose of 80 mg/m(2) on days 1, 8, and 15 of each 4 week cycle. Randomisation was stratified according to previous use of trastuzumab and visceral metastasis. Patients and investigators were masked to the assigned treatments. Identity of experimental treatments was concealed by use of everolimus and placebo that were identical in packaging, labelling, appearance, and administration schedule. The two primary objectives were investigator-assessed progression-free survival in the full study population and in the subset of patients with hormone receptor-negative breast cancer at baseline; the latter was added during the course of the study, before unmasking based on new clinical and biological findings from other studies. All efficacy analyses were based on the intention-to-treat population. Enrolment for this trial is closed and results of the final progression-free survival analyses are presented here. This trial is registered with ClinicalTrials.gov, number NCT00876395.

FINDINGS

Between Sept 10, 2009, and Dec 16, 2012, 719 patients were randomly assigned to receive everolimus (n=480) or placebo (n=239). Median follow-up was 41·3 months (IQR 35·4-46·6). In the full population, median progression-free survival was 14·95 months (95% CI 14·55-17·91) with everolimus versus 14·49 months (12·29-17·08) with placebo (hazard ratio 0·89, 95% CI 0·73-1·08; p=0·1166). In the HR-negative subpopulation (n=311), median progression-free survival with everolimus was 20·27 months (95% CI 14·95-24·08) versus 13·08 months (10·05-16·56) with placebo (hazard ratio 0·66, 95% CI 0·48-0·91; p=0·0049); however, the protocol-specified significance threshold (p=0·0044) was not crossed. The most common adverse events with everolimus were stomatitis (314 [67%] of 472 patients in the everolimus group vs 77 [32%] of 238 patients in the placebo group), diarrhoea (267 [57%] vs 111 [47%] patients), and alopecia (221 [47%] vs 125 [53%]). The most frequently reported grade 3 or 4 adverse events in the everolimus group versus the placebo group were neutropenia (117 [25%] vs 35 [15%]), stomatitis (59 [13%] vs three [1%]), anaemia (46 [10%] vs six [3%]) and diarrhoea (43 [9%] vs 10 [4%]) On-treatment adverse event-related deaths were reported in 17 (4%) patients in the everolimus group and none in the placebo group.

INTERPRETATION

Although progression-free survival was not significantly different between groups in the full analysis population, the 7·2 months prolongation we noted with the addition of everolimus in the HR-negative, HER2-positive population warrants further investigation, even if it did not meet prespecified criteria for significance. The safety profile was generally consistent with what was previously reported in BOLERO-3. Proactive monitoring and early management of adverse events in patients given everolimus and chemotherapy is crucial.

FUNDING

Novartis Pharmaceuticals.

Everolimus plus exemestane for the treatment of advanced breast cancer: a review of subanalyses from BOLERO-2

Hormone receptor-positive breast cancer is typically managed with endocrine therapies. However, resistance to endocrine therapy results in disease progression in a large proportion of breast cancers. Through the understanding of the mechanisms of endocrine resistance, identification of implicated pathways and targets has led to the development of novel agents targeting these pathways. Phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway aberrations are common in breast cancer, with increased PI3K/AKT/mTOR signaling associated with resistance to endocrine and human epidermal growth factor receptor 2 (HER2)-targeted therapies. The mTOR inhibitor everolimus, in combination with exemestane, has been approved for patients with advanced hormone receptor-positive/HER2-negative breast cancer who progress on prior nonsteroidal aromatase inhibitor therapy based on results reported in the Breast Cancer Trials of Oral Everolimus-2 (BOLERO-2) study. This review will summarize the overall findings from BOLERO-2 and will consider available subanalyses by age, Asian origin, visceral or bone metastases, and prior therapy, with the aim of identifying populations most likely to benefit from everolimus therapy. The review will also summarize safety findings and their management and the effects of everolimus on quality of life.

Novel agents and associated toxicities of inhibitors of the pi3k/Akt/mtor pathway for the treatment of breast cancer

The pi3k/Akt/mtor (phosphatidylinositol 3 kinase/ Akt/mammalian target of rapamycin) signalling pathway is an established driver of oncogenic activity in human malignancies. Therapeutic targeting of this pathway holds significant promise as a treatment strategy. Everolimus, an mtor inhibitor, is the first of this class of agents approved for the treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer. Everolimus has been associated with significant improvements in progression-free survival; however, it is also associated with increased toxicity related to its specific mechanism of action.

METHODS

A comprehensive review of the literature conducted using a focused medline search was combined with a search of current trials at http://ClinicalTrials.gov/. Summary tables of the toxicities of the various classes of pi3k/Akt/mtor inhibitors were created. A broad group of Canadian health care professionals was assembled to review the data and to produce expert opinion and summary recommendations for possible best practices in managing the adverse events associated with these pathway inhibitors.

RESULTS

Differing toxicities are associated with the various classes of pi3k/Akt/mtor pathway inhibitors. The most common unique adverse events observed in everolimus clinical trials in breast cancer include stomatitis (all grades: approximately 60%), noninfectious pneumonitis (15%), rash (40%), hyperglycemia (15%), and immunosuppression (40%). To minimize grades 3 and 4 toxicities and to attempt to attain optimal outcomes, effective management of those adverse events is critical. Management should be interdisciplinary and should use approaches that include education, early recognition, active intervention, and potentially prophylactic strategies.

DISCUSSION

Everolimus likely represents the first of many complex oral targeted therapies for the treatment of breast cancer. Using this agent as a template, it is essential to establish best practices involving and integrating multiple disciplines for the management of future pi3k/Akt/mtor signalling pathway inhibitors.

A new era of improving progression-free survival with dual blockade in postmenopausal HR(+), HER2(-) advanced breast cancer

Disease progression despite existing endocrine therapies remains a major challenge to the effective management of hormone-receptor-positive (HR(+)), human epidermal growth factor receptor-2-negative (HER2(-)), advanced breast cancer. Recent advances in elucidating the molecular mechanisms of disease progression have identified the existence of adaptive "cross-talk" between the estrogen receptor (ER) and various growth factor receptor and intracellular signaling pathways, allowing breast cancer cells to escape the inhibitory effects of endocrine therapy. These findings provide the clinical rationale for enhancing or extending endocrine sensitivity by combining endocrine therapy with a targeted agent against a compensatory pathway. In BOLERO-2, adding the mTOR inhibitor everolimus to endocrine therapy significantly improved progression-free survival (PFS) in patients with HR(+) advanced breast cancer previously treated with nonsteroidal aromatase inhibitor therapy. Notably, PFS benefits were comparable in subgroup analyses of first- and later-line settings. These results contrast with those of the large first-line HORIZON study, wherein adding the mTOR inhibitor temsirolimus to endocrine therapy did not improve PFS. Therefore, it is unclear whether a targeted agent should only be combined with endocrine therapy to restore endocrine sensitivity or whether it may also prevent or delay resistance in hormone-sensitive advanced breast cancer. Numerous additional targeted agents are currently being evaluated in combination with endocrine therapies, including PI3K, cyclin-dependent kinase 4/6, SRC, and histone deacetylase inhibitors. Appropriate patient selection based on prior treatment history will become increasingly important in maximizing the incremental benefit derived from these new agents combined with existing endocrine therapies in HR(+) advanced breast cancer.

Everolimus plus exemestane for hormone-receptor-positive, human epidermal growth factor receptor-2-negative advanced breast cancer: overall survival results from BOLERO-2†

BACKGROUND

The BOLERO-2 study previously demonstrated that adding everolimus (EVE) to exemestane (EXE) significantly improved progression-free survival (PFS) by more than twofold in patients with hormone-receptor-positive (HR(+)), HER2-negative advanced breast cancer that recurred or progressed during/after treatment with nonsteroidal aromatase inhibitors (NSAIs). The overall survival (OS) analysis is presented here.

PATIENTS AND METHODS

BOLERO-2 is a phase III, double-blind, randomized international trial comparing EVE 10 mg/day plus EXE 25 mg/day versus placebo (PBO) + EXE 25 mg/day in postmenopausal women with HR(+) advanced breast cancer with prior exposure to NSAIs. The primary end point was PFS by local investigator assessment; OS was a key secondary end point.

RESULTS

At the time of data cutoff (3 October 2013), 410 deaths had occurred and 13 patients remained on treatment. Median OS in patients receiving EVE + EXE was 31.0 months [95% confidence interval (CI) 28.0-34.6 months] compared with 26.6 months (95% CI 22.6-33.1 months) in patients receiving PBO + EXE (hazard ratio = 0.89; 95% CI 0.73-1.10; log-rank P = 0.14). Poststudy treatments were received by 84% of patients in the EVE + EXE arm versus 90% of patients in the PBO + EXE arm. Types of poststudy therapies were balanced across arms, except for chemotherapy (53% EVE + EXE versus 63% PBO + EXE). No new safety concerns were identified.

CONCLUSIONS

In BOLERO-2, adding EVE to EXE did not confer a statistically significant improvement in the secondary end point OS despite producing a clinically meaningful and statistically significant improvement in the primary end point, PFS (4.6-months prolongation in median PFS; P < 0.0001). Ongoing translational research should further refine the benefit of mTOR inhibition and related pathways in this treatment setting.

TRIAL REGISTRATION NUMBER

NCT00863655.