Phase II randomized study of neoadjuvant everolimus plus letrozole compared with placebo plus letrozole in patients with estrogen receptor-positive breast cancer

Erlotinib, erlotinib-sulindac versus placebo: a randomized, double-blind, placebo-controlled window trial in operable head and neck cancer

PURPOSE

The EGF receptor (EGFR) and COX2 pathways are upregulated in head and neck squamous cell carcinoma (HNSCC). Preclinical models indicate synergistic antitumor activity from dual blockade. We conducted a randomized, double-blind, placebo-controlled window trial of erlotinib, an EGFR inhibitor; erlotinib plus sulindac, a nonselective COX inhibitor; versus placebo.

EXPERIMENTAL DESIGN

Patients with untreated, operable stage II-IVb HNSCC were randomized 5:5:3 to erlotinib, erlotinib-sulindac, or placebo. Tumor specimens were collected before and after seven to 14 days of treatment. The primary endpoint was change in Ki67 proliferation index. We hypothesized an ordering effect in Ki67 reduction: erlotinib-sulindac > erlotinib > placebo. We evaluated tissue microarrays by immunohistochemistry for pharmacodynamic modulation of EGFR and COX2 signaling intermediates.

RESULTS

From 2005-2009, 47 patients were randomized for the target 39 evaluable patients. Thirty-four tumor pairs were of sufficient quality to assess biomarker modulation. Ki67 was significantly decreased by erlotinib or erlotinib-sulindac (omnibus comparison, two-sided Kruskal-Wallis, P = 0.04). Wilcoxon pairwise contrasts confirmed greater Ki67 effect in both erlotinib groups (erlotinib-sulindac vs. placebo, P = 0.043; erlotinib vs. placebo, P = 0.027). There was a significant trend in ordering of Ki67 reduction: erlotinib-sulindac > erlotinib > placebo (two-sided exact Jonckheere-Terpstra, P = 0.0185). Low baseline pSrc correlated with greater Ki67 reduction (R(2) = 0.312, P = 0.024).

CONCLUSIONS

Brief treatment with erlotinib significantly decreased proliferation in HNSCC, with additive effect from sulindac. Efficacy studies of dual EGFR-COX inhibition are justified. pSrc is a potential resistance biomarker for anti-EGFR therapy, and warrants investigation as a molecular target.

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

BACKGROUND

In the BOLERO-2 trial, everolimus (EVE), an inhibitor of mammalian target of rapamycin, demonstrated significant clinical benefit with an acceptable safety profile when administered with exemestane (EXE) in postmenopausal women with hormone receptor-positive (HR(+)) advanced breast cancer. We report on the incidence, time course, severity, and resolution of treatment-emergent adverse events (AEs) as well as incidence of dose modifications during the extended follow-up of this study.

PATIENTS AND METHODS

Patients were randomized (2:1) to receive EVE 10 mg/day or placebo (PBO), with open-label EXE 25 mg/day (n = 724). The primary end point was progression-free survival. Secondary end points included overall survival, objective response rate, and safety. Safety evaluations included recording of AEs, laboratory values, dose interruptions/adjustments, and study drug discontinuations.

RESULTS

The safety population comprised 720 patients (EVE + EXE, 482; PBO + EXE, 238). The median follow-up was 18 months. Class-effect toxicities, including stomatitis, pneumonitis, and hyperglycemia, were generally of mild or moderate severity and occurred relatively early after treatment initiation (except pneumonitis); incidence tapered off thereafter. EVE dose reduction and interruption (360 and 705 events, respectively) required for AE management were independent of patient age. The median duration of dose interruption was 7 days. Discontinuation of both study drugs because of AEs was higher with EVE + EXE (9%) versus PBO + EXE (3%).

CONCLUSIONS

Most EVE-associated AEs occur soon after initiation of therapy, are typically of mild or moderate severity, and are generally manageable with dose reduction and interruption. Discontinuation due to toxicity was uncommon. Understanding the time course of class-effect AEs will help inform preventive and monitoring strategies as well as patient education.

TRIAL REGISTRATION NUMBER

NCT00863655.

Targeting the PI3K/AKT/mTOR pathway in estrogen receptor-positive breast cancer

Approximately 70-75% of breast cancers express the estrogen receptor (ER), indicating a level of dependence on estrogen for growth. Endocrine therapy is an important class of target-directed therapy that blocks the growth-promoting effects of estrogen via ER. Although endocrine therapy continues to be the cornerstone of effective treatment of ER-positive (ER+) breast cancer, many patients with advanced ER+ breast cancer encounter de novo or acquired resistance and require more aggressive treatment such as chemotherapy. Novel approaches are needed to augment the benefit of existing endocrine therapies by prolonging time to disease progression, preventing or overcoming resistance, and delaying the use of chemotherapy. The phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway is a key intracellular signaling system that drives cellular growth and survival; hyperactivation of this pathway is implicated in the tumorigenesis of ER+ breast cancer and in resistance to endocrine therapy. Moreover, preclinical and clinical evidence show that PI3K/AKT/mTOR pathway inhibition can augment the benefit of endocrine therapy in ER+ breast cancer, from the first-line setting and beyond. This article will review the fundamental role of the PI3K/AKT/mTOR pathway in driving ER+ breast tumors, and its inherent interdependence with ER signaling. In addition, ongoing strategies to combine PI3K/AKT/mTOR pathway inhibitors with endocrine therapy for improved clinical outcomes, and methods to identify patient populations that would benefit most from inhibition of the PI3K/AKT/mTOR pathway, will be evaluated.

Open-label randomized clinical trial of standard neoadjuvant chemotherapy with paclitaxel followed by FEC versus the combination of paclitaxel and everolimus followed by FEC in women with triple receptor-negative breast cancer†

BACKGROUND

Everolimus synergistically enhances taxane-induced cytotoxicity in breast cancer cells in vitro and in vivo in addition to demonstrating a direct antiproliferative activity. We aim to determine pharmacodynamics changes and response of adding everolimus to standard neoadjuvant chemotherapy in triple-negative breast cancer (TNBC).

PATIENTS AND METHODS

Phase II study in patients with primary TNBC randomized to T-FEC (paclitaxel 80 mg/m(2) i.v. weekly for 12 weeks, followed by 5-fluorouracil 500 mg/m(2), epirubicin 100 mg/m(2), and cyclophosphamide 500 mg/m(2) every 3 weeks for four cycles) versus TR-FEC (paclitaxel 80 mg/m(2) i.v. and everolimus 30 mg PO weekly for 12 weeks, followed by FEC). Tumor samples were collected to assess molecular changes in the PI3K/AKT/mTOR pathway, at baseline, 48 h, 12 weeks, and at surgery by reverse phase protein arrays (RPPA). Clinical end points included 12-week clinical response rate (12-week RR), pathological complete response (pCR), and toxicity.

RESULTS

Sixty-two patients were registered, and 50 were randomized, 27 received T-FEC, and 23 received TR-FEC. Median age was 48 (range 31-75). There was downregulation of the mTOR pathway at 48 h in the TR-FEC arm. Twelve-week RR by ultrasound were 29.6% versus 47.8%, (P = 0.075), and pCR were 25.9% versus 30.4% (P = 0.76) for T-FEC and TR-FEC, respectively. mTOR downregulation at 48 h did not correlate with 12-week RR in the TR-FEC group (P = 0.58). Main NCI grade 3/4 toxicities included anemia, neutropenia, rash/desquamation, and vomiting in both arms. There was one case of grade 3 pneumonitis in the TR-FEC arm. No grade 3/4 stomatitis occurred.

CONCLUSION

The addition of everolimus to paclitaxel was well tolerated. Everolimus downregulated mTOR signaling but downregulation of mTOR at 48 h did not correlate with 12-week RR in the TR-FEC group.

CLINICAL TRIAL NUMBER

NCT00499603.

Phase II randomized trial of neoadjuvant metformin plus letrozole versus placebo plus letrozole for estrogen receptor positive postmenopausal breast cancer (METEOR)

Background

Neoadjuvant endocrine therapy with an aromatase inhibitor has shown efficacy comparable to that of neoadjuvant chemotherapy in patients with postmenopausal breast cancer. Preclinical and clinical studies have shown that the antidiabetic drug metformin has anti-tumor activity. This prospective, multicenter, phase II randomized, placebo controlled trial was designed to evaluate the direct anti-tumor effect of metformin in non-diabetic postmenopausal women with estrogen-receptor (ER) positive breast cancer.

Methods/Design

Patients meeting the inclusion criteria and providing written informed consent will be randomized to 24 weeks of neoadjuvant treatment with letrozole (2.5 mg/day) and either metformin (2000 mg/day) or placebo. Target accrual number is 104 patients per arm. The primary endpoint will be clinical response rate, as measured by calipers. Secondary endpoints include pathologic complete response rate, breast conserving rate, change in Ki67 expression, breast density change, and toxicity profile. Molecular assays will be performed using samples obtained before treatment, at week 4, and postoperatively.

Discussion

This study will provide direct evidence of the anti-tumor effect of metformin in non-diabetic, postmenopausal patients with ER-positive breast cancer.

Trial registration

ClinicalTrials.gov Identifier NCT01589367

Double-blind, placebo-controlled, multicenter, randomized, phase IIb neoadjuvant study of letrozole-lapatinib in postmenopausal hormone receptor-positive, human epidermal growth factor receptor 2-negative, operable breast cancer

PURPOSE

This is a randomized, double-blind, placebo-controlled study aimed to evaluate the clinical and biologic effects of letrozole plus lapatinib or placebo as neoadjuvant therapy in hormone receptor (HR) -positive/human epidermal growth factor receptor 2 (HER2) -negative operable breast cancer.

METHODS

Ninety-two postmenopausal women with stage II to IIIA primary breast cancer were randomly assigned to preoperative therapy consisting of 6 months of letrozole 2.5 mg orally daily plus lapatinib 1,500 mg orally daily or placebo. Surgery was performed within 2 weeks from the last study medication. Clinical response was assessed by ultrasonography. Pre- and post-treatment samples were evaluated for selected biomarkers. Fresh-frozen tissue samples were collected for genomic analyses.

RESULTS

Numerically similar clinical response rates (partial + complete response) were observed (70% for letrozole-lapatinib and 63% for letrozole-placebo). Toxicities were generally mild and manageable. A significant decrease in Ki-67 and pAKT expression from baseline to surgery was observed in both arms. Overall, 34 patients (37%) had a mutation in PIK3CA exon 9 or 20. In the letrozole-lapatinib arm, the probability of achieving a clinical response was significantly higher in the presence of PIK3CA mutation (objective response rate, 93% v 63% in PIK3CA wild type; P = .040).

CONCLUSION

The combination of letrozole-lapatinib in early breast cancer was feasible, with expected and manageable toxicities. In unselected estrogen receptor-positive/HER2-negative patients, letrozole-lapatinib and letrozole-placebo resulted in a similar overall clinical response rate and similar effect on Ki-67 and pAKT. Our secondary end point findings of a significant correlation between PIK3CA mutation and response to letrozole-lapatinib in HR-positive/HER2-negative early breast cancer must now be independently confirmed.

Neoadjuvant endocrine therapy in breast cancer

SUMMARY Preoperative therapy in breast cancer was initially considered a therapeutic tool to downstage large tumors. In the last few years, neoadjuvant endocrine therapy has emerged as an active approach for the treatment of locally advanced estrogen receptor-positive breast cancer. Moreover, the parallel results obtained with neoadjuvant and adjuvant endocrine trials suggest that rationale for future adjuvant designs should be based on previously confirmed positive outcomes obtained in neoadjuvant studies. Ki-67, a proliferation-associated antigen determined by serial biopsies during therapy, has been validated as a biomarker and can provide useful information to define prognosis and establish therapeutic decisions. This review focuses on the classical indications of neoadjuvant endocrine therapy, the parallelism between adjuvant and neoadjuvant studies and the potential role of this approach to predict outcomes based on short-term molecular markers in estrogen receptor-positive breast cancer.

Clinical development of mTOR inhibitors in breast cancer

The mammalian target of rapamycin (mTOR) pathway is a central pathway that regulates mRNA translation, protein synthesis, glucose metabolism, lipid synthesis and autophagy, and is involved in malignant transformation. Several randomized trials have shown that the use of mTOR inhibitors could improve patient outcome with hormone receptor-positive or human epidermal growth factor receptor-2-positive breast cancer. This review analyzes new perspectives from these trials. Preclinical studies have suggested that the mTOR pathway may play a role in the resistance to hormone therapy, trastuzumab and chemotherapy for breast cancer. This concept has been tested in clinical trials for neoadjuvant treatment and for metastatic breast cancer patients. Also, much effort has gone into the identification of biomarkers that will allow for more precise stratification of patients. Findings from these studies will provide indispensable tools for the design of future clinical trials and identify new perspectives and challenges for researchers and clinicians.

Development and validation of a gene expression score that predicts response to fulvestrant in breast cancer patients

Fulvestrant is a selective estrogen receptor antagonist. Based on the measured growth inhibition of 60 human cancer cell lines (NCI60) in the presence of fulvestrant, as well as the baseline gene expression of the 60 cell lines, a gene expression score that predicts response to fulvestrant was developed. The score is based on 414 genes, 103 of which show increased expression in sensitive cell lines, while 311 show increased expression in the non-responding cell lines. The sensitivity genes primarily sense signaling through estrogen receptor alpha, whereas the resistance genes modulate the PI3K signaling pathway. The latter genes suggest that resistance to fulvestrant can be overcome by drugs targeting the PI3K pathway. The level of this gene expression score and its correlation with fulvestrant response was measured in a panel of 20 breast cancer cell lines. The predicted sensitivity matched the measured sensitivity well (CC = -0.63, P = 0.003). The predictor was applied to tumor biopsies obtained from a Phase II clinical trial. The sensitivity of each patient to treatment with fulvestrant was predicted based on the RNA profile of the biopsy taken before neoadjuvant treatment and without knowledge of the subsequent response. The prediction was then compared to clinical response to show that the responders had a significantly higher sensitivity prediction than the non-responders (P = 0.01). When clinical covariates, tumor grade and estrogen receptor H-score, were included in the prediction, the difference in predicted senstivity between responders and non-responders improved (P = 0.003). Using a pre-defined cutoff to separate patients into predicted sensitive and predicted resistant yielded a positive predictive value of 88% and a negative predictive value of 100% when compared to clinical data. We conclude that pre-screening patients with the new gene expression predictor has the potential to identify those postmenopausal women with locally advanced, estrogen-receptor-positive breast cancer most likely to respond to fulvestrant.

Using multiple targeted therapies in oncology: considerations for use, and progress to date in breast cancer

There has been significant progress in our basic understanding of drugs and targets in the management of breast cancer. Recent breast cancer clinical trials have examined whether combinations of drugs targeting transmembrane receptors or their downstream effectors involved in cell signal transduction can increase response rates and overcome acquired and/or de novo drug resistance compared to a single targeted agent with or without systemic chemotherapy. We reviewed published clinical trials and conference proceedings examining combinations of targeted therapies across different breast cancer subtypes. Improvements in pathological complete response (pCR) rates and progression free survival (PFS) in preoperatively treated and metastatic human epidermal growth factor 2 (HER2)-positive breast cancer, respectively, have been observed with combinations of anti-HER2 therapies given concomitantly. Promising results were also observed in estrogen receptor (ER)-positive, HER2-negative breast cancer using a mammalian target of rapamycin inhibitor with tamoxifen or an aromatase inhibitor (AI) in the preoperative setting and for patients with metastatic breast cancer that had previously progressed on endocrine therapy alone. A recent phase II trial reported a statistically significant improvement in PFS with the addition of an oral inhibitor of cyclin-dependent kinase 4/6 to letrozole compared to letrozole alone (26.1 versus 7.5 months). A phase III study is planned for early 2013. On the basis of preclinical data, clinical trials have examined combinations of hormonal agents such as fulvestrant with an AI. However, the results are conflicting. Early data indicated that poly (ADP-ribose) polymerase (PARP) inhibitors exploiting the concept of synthetic lethality would offer improved outcomes for patients with ER-negative, progesterone receptor (PR)-negative, HER2-negative breast cancer often referred to as triple negative breast cancer (TNBC); however, data in the phase III setting failed to confirm these findings but this may be because the drug was not a true PARP inhibitor. Chemotherapy continues to be the mainstay of treatment for TNBC until specific drugs and their associated targets are identified. As advances in medical technologies continue to identify multiple molecularly distinct breast cancer subgroups that are predicted to respond to combinations of targeted agents new challenges have arisen. In particular, how do we evaluate the safety and efficacy of these new drug combinations in relatively small subgroups of patients? Novel clinical trial designs will be required and increasingly regulatory agencies will require companion diagnostic tests that can identify the subgroups likely to respond to these therapies. The US Food and Drug Administration is assessing the role of pCR in breast cancer studies as a surrogate endpoint to predict clinical benefit in the accelerated drug approval process.

Everolimus in combination with exemestane: a review of its use in the treatment of patients with postmenopausal hormone receptor-positive, HER2-negative advanced breast cancer

Oral everolimus (Afinitor(®)) in combination with exemestane is indicated for the treatment of hormone receptor-positive, human epidermal growth factor receptor (HER) 2-negative advanced breast cancer in postmenopausal women after failure of treatment with letrozole or anastrozole (in the USA) or after recurrence of progression following a nonsteroidal aromatase inhibitor (AI) in women without symptomatic visceral disease (in the EU). Everolimus, a selective inhibitor of mammalian target of rapamycin (mTOR), inhibits the downstream signalling events of the mTOR pathway. This review summarizes the pharmacology of everolimus and reviews its efficacy and tolerability when administered in combination with exemestane in postmenopausal women with oestrogen receptor-positive, HER2-negative advanced breast cancer refractory to nonsteroidal AIs. In the well-designed BOLERO-2 study, the addition of everolimus to exemestane was shown to significantly prolong progression-free survival in this patient population. However, treatment-emergent adverse events and treatment discontinuations occurred more frequently with combination therapy than with exemestane alone, suggesting a need for careful benefit/risk assessment prior to initiating therapy. Mature survival data from this study are awaited and additional studies would help to further demonstrate the benefit of combination therapy. Nevertheless, current evidence suggests that everolimus plus exemestane combination therapy may be a useful treatment option in patients with postmenopausal hormone receptor-positive, HER2-negative, advanced breast cancer refractory to nonsteroidal AIs.

Breast cancer: current and future endocrine therapies

Endocrine therapy forms a central modality in the treatment of estrogen receptor positive breast cancer. The routine use of 5 years of adjuvant tamoxifen has improved survival rates for early breast cancer, and more recently has evolved in the postmenopausal setting to include aromatase inhibitors. The optimal duration of adjuvant endocrine therapy remains an active area of clinical study with recent data supporting 10 years rather than 5 years of adjuvant tamoxifen. However, endocrine therapy is limited by the development of resistance, this can occur by a number of possible mechanisms and numerous studies have been performed which combine endocrine therapy with agents that modulate these mechanisms with the aim of preventing or delaying the emergence of resistance. Recent trial data regarding the combination of the mammalian target of rapamycin (mTOR) inhibitor, everolimus with endocrine therapy have resulted in a redefinition of the clinical treatment pathway in the metastatic setting. This review details the current endocrine therapy utilized in both early and advanced disease, as well as exploring potential new targets which modulate pathways of resistance, as well as agents which aim to modulate adrenal derived steroidogenic hormones.

The phosphoinositide-3-kinase-Akt-mTOR pathway as a therapeutic target in breast cancer

The phosphoinositide-3-kinase (PI3-kinase)-Akt-mTOR pathway is a central signal transduction pathway that regulates many critical aspects of normal and cancer physiology, including cell proliferation, apoptosis, cell morphology and migration, protein synthesis, and integration of metabolism. In breast cancer, somatic mutations that activate the pathway occur in more than 50% of tumors, underscoring the potentially broad impact of targeting the pathway for therapy. A vast body of preclinical data demonstrates the efficacy of pathway inhibition on tumor growth, and evidence also shows that activation of the pathway occurs in models of acquired resistance to hormonal therapy. This preclinical work led to the investigation of allosteric mTOR inhibitors, everolimus and temsirolimus, in metastatic hormone receptor-positive breast cancer. The recent BOLERO-2 trial comparing everolimus plus exemestane versus placebo plus exemestane in women with resistance to nonsteroidal aromatase inhibitors demonstrated a 6-month improvement in progression-free survival and led to FDA approval of everolimus for this indication in the United States. This landmark trial is the first demonstration of significant clinical benefit using drugs targeting this pathway in breast cancer. Many questions remain about the role of everolimus and other pathway-targeting drugs in clinical development in breast cancer treatment. This article reviews the role of the PI3-kinase-Akt-mTOR pathway in breast cancer biology and the clinical trial evidence available to date.

Targeting multiple pathways in breast cancer

SUMMARY Breast cancer (BC) is a highly prevalent disease. Worldwide, it is the most common cancer diagnosed and the leading cause of cancer death in women, making this disease a very important focus of interest and research. There is great heterogeneity in clinical outcomes among women diagnosed with BC, possibly indicating that biological heterogeneity is a major factor interfering with tumor development and progression. Presently, it is known that specific genetic expression patterns divide BC into distinct molecular subtypes. In fact, a better understanding of molecular profiles in BC and more advances in biological technology has divided each BC subtype further into additional subcategories. This means that more pathways are being recognized as important drivers or contributors to BC development and progression. The implication in BC treatment and management can be enormous. A more complete knowledge of the biology of the tumor has many implications. Development of therapies that specifically target the activated pathways can allow the delivery of more effective treatments and spare patients from treatments that would only cause side effects. This article will focus on exploring and reviewing the different molecular pathways involved in each clinically relevant BC subtype, namely hormone receptor-positive, HER2-positive and triple-negative BC. For each BC subtype, novel targeted therapies that are already incorporated in clinical practice, as well as drugs in clinical development, will be described, including the safety profiles of each one. We will highlight the major molecular pathways involved in each BC subtype, providing a rationale for the development of specific targeted therapies. Mechanisms of resistance to conventional therapies by pathway activation will be discussed. Strategies to overcome resistance are also a major focus of this review.

Everolimus: a new hope for patients with breast cancer

BACKGROUND

Breast cancer cells can develop resistance to standard hormonal treatment and chemotherapy with the activation of the mTOR pathway; this is supported by results of preclinical and clinical studies. In clinical trials, the addition of everolimus to hormonal treatment or anti-HER2 treatment improved the outcomes of breast cancer patients. The aim of this review is to discuss the efficacy and safety data of everolimus in all categories of breast cancer in recent published studies.

SCOPE

Everolimus showed positive results in clinical studies. A literature search was made from PubMed, ASCO and San Antonio Breast Cancer Symposium Meeting abstracts by using the following search key words: 'everolimus', 'RAD001', 'mTOR inhibitor', 'breast cancer' 'endocrine therapy resistance' and 'HER-2 targeted therapies'. The last search was on June 10, 2013. The most important limitation of our review is that most of the data on everolimus rely on phase I and II trials.

FINDINGS

Preclinical studies showed that mTOR activation can be the responsible mechanism in all subgroups of breast cancer. Results of both the TAMRAD and BOLERO-2 studies have showed that mTOR inhibition in combination with endocrine therapy can be a new treatment strategy for MBC patients who are resistant to aromatase inhibitors. In the BOLERO-2 study, time to deterioration in health-related quality of life was also significantly higher in the everolimus and exemestane arm compared to the exemestane plus placebo arm. The recently completed BOLERO-3 study showed that mTOR inhibition in combination with trastuzumab plus vinorelbine treatment significantly improved PFS compared to trastuzumab plus vinorelbine alone in trastuzumab-resistant MBC patients.

CONCLUSION

Recent trials have shown that everolimus has produced promising anti-tumor activity in combination with trastuzumab in HER2-positive metastatic breast cancer and in combination with exemestane in patients with hormone-receptor-positive metastatic breast cancer who had recurrence or progression while receiving a nonsteroidal aromatase inhibitor. Results of ongoing studies with everolimus show evidence that using everolimus in earlier stages of the disease, namely in the adjuvant and neoadjuvant settings, could be benefical.

Everolimus

Everolimus (RAD001, Afinitor®) is an oral protein kinase inhibitor of the mammalian target of rapamycin (mTOR) serine/threonine kinase signal transduction pathway. The mTOR pathway regulates cell growth, proliferation, and survival and is frequently deregulated in cancer. Everolimus has been approved by the FDA and the EMA for the treatment of advanced renal cell carcinoma (RCC), subependymal giant cell astrocytoma (SEGA) associated with tuberous sclerosis (TSC), pancreatic neuroendocrine tumors (PNET), in combination with exemestane in advanced hormone-receptor (HR)-positive, HER2-negative breast cancer. Everolimus shows promising clinical activity in additional indications. Multiple phase 2 and phase 3 trials of everolimus alone or in combination are ongoing and will help to further elucidate the role of mTOR in oncology. For a review on everolimus as immunosuppressant, please consult other sources.

Hematologic toxicities associated with mTOR inhibitors temsirolimus and everolimus in cancer patients: a systematic review and meta-analysis

BACKGROUND

Mammalian target of rapamycin (mTOR) inhibitors, temsirolimus and everolimus, are currently approved for the treatment of several malignancies. Hematological toxicities have been reported with these drugs, but overall incidence and relative risk remains undefined. We perform an up-to-date meta-analysis to determine the incidence and risk of hematologic toxicities associated with mTOR inhibitors.

METHODS

Several databases were searched, including PubMed, Embase and Cochrane databases. Eligible studies included prospective phase II and III trials of temsirolimus and everolimus with adequate safety data profile reporting anemia, leucopenia, neutropenia or thrombocytopenia. Overall incidence rates, relative risk (RR), and 95% confidence intervals (CI) were calculated by using either random effects or fixed effects models according to the heterogeneity of included studies.

RESULTS

A total of 5436 patients with a variety of solid tumors from 26 clinical trials were included for the meta-analysis. The overall incidences of mTOR inhibitor associated all-grade and high-grade hematologic toxicities were, respectively: anemia--38.8% and 7.5%; leucopenia--19.6% and 1.8%; neutropenia--14.9% and 5.6%; thrombocytopenia--33.1% and 3.6%. Compared to placebo/control arms, mTOR inhibitors were associated with a significantly increased risk of all-grade (RR 2.05, 95% CI: 1.52-2.77; p < 0.001) and high-grade anemia (RR 1.57, 95% CI: 1.20-2.05; p = 0.001), all-grade (RR 6.03, 95% CI: 2.76-13.14; p < 0.001) and high-grade thrombocytopenia (RR 2.73, 95% CI: 1.87-3.99; p < 0.001). Additionally, a non-significantly increased risk of all-grade leucopenia (RR 1.46, 95% CI: 0.66-3.23; p = 0.34) and neutropenia (RR 1.77, 95% CI: 0.80-3.93; p = 0.16) was observed in the mTOR inhibitor group, while the risk of high-grade leucopenia (RR 0.53, 95% CI: 0.31-0.90, p = 0.019) and neutropenia (RR 0.96, 95% CI: 0.62-1.51; p = 0.87) did not increase. Similar results were also observed in sub-group analysis according to mTOR inhibitor based regimens.

CONCLUSIONS

The use of mTOR inhibitors is associated with a significant increase in the risk of developing all-grade and high-grade anemia and thrombocytopenia compared with placebo/control arms.

Overview of diagnostic/targeted treatment combinations in personalized medicine for breast cancer patients

Breast cancer includes a body of molecularly distinct subgroups, characterized by different presentation, prognosis, and sensitivity to treatments. Significant advances in our understanding of the complex architecture of this pathology have been achieved in the last few decades, thanks to new biotechnologies that have recently come into the research field and the clinical practice, giving oncologists new instruments that are based on biomarkers and allowing them to set up a personalized approach for each individual patient. Here we review the main treatments available or in preclinical development, the biomolecular diagnostic and prognostic approaches that changed our perspective about breast cancer, giving an overview of targeted therapies that represent the current standard of care for these patients. Finally, we report some examples of how new technologies in clinical practice can set in motion the development of new drugs.

Neoadjuvant therapy as a platform for drug development and approval in breast cancer

The traditional drug development process in breast cancer based on large phase III studies has serious limitations and needs a major overhaul. Searching for new approaches, the testing of novel agents in the preoperative (neoadjuvant) setting approach offers a potentially rapid and efficient strategy for drug development utilizing pathologic complete response (path CR), a surrogate marker for survival, as the primary endpoint. In addition, neoadjuvant studies allow the assessment of drug effects on the target (pharmacodynamic response) and the development of predictive biomarkers of response. Molecular profiling of the residual tumor in the surgical specimen may also provide insights into actionable mechanisms of resistance. Recognizing the potential of neoadjuvant trials for drug development, the U.S. Food and Drug Administration (FDA) recently announced consideration of neoadjuvant trials for accelerated drug approval in early breast cancer, particularly for tumors with high risk of recurrence and unfavorable prognosis, and provided accelerated approval to neoadjuvant pertuzumab in September 2013. The FDA has emphasized that while improvement in path CR could be utilized for "accelerated" approval, improvement in survival will still need to be demonstrated for "regular" approval. Key considerations in conduct of such neoadjuvant drug development trials include (i) study design such as utilization of biomarker stratified design to evaluate a biomarker that could enrich response, (ii) definition of path CR, (iii) distribution of factors that influence path CR between the treatment arms, (iv) prespecified plan for follow-up to obtain data on survival, and (v) safety as it involves a patient population with curable disease. In the years to come, we anticipate an increase in the number of neoadjuvant trials testing novel therapies that hopefully will open a new path in bringing efficacious new therapies to patients with breast cancer.

Targeted cancer therapy--are the days of systemic chemotherapy numbered?

Targeted therapy or molecular targeted therapy has been defined as a type of treatment that blocks the growth of cancer cells by interfering with specific cell molecules required for carcinogenesis and tumor growth, rather than by simply interfering with all rapidly dividing cells as with traditional chemotherapy. There is a growing number of FDA approved monoclonal antibodies and small molecules targeting specific types of cancer suggestive of the growing relevance of this therapeutic approach. Targeted cancer therapies, also referred to as "Personalized Medicine", are being studied for use alone, in combination with other targeted therapies, and in combination with chemotherapy. The objective of personalized medicine is the identification of patients that would benefit from a specific treatment based on the expression of molecular markers. Examples of this approach include bevacizumab and olaparib, which have been designated as promising targeted therapies for ovarian cancer. Combinations of trastuzumab with pertuzumab, or T-DM1 and mTOR inhibitors added to an aromatase inhibitor are new therapeutic strategies for breast cancer. Although this approach has been seen as a major step in the expansion of personalized medicine, it has substantial limitations including its high cost and the presence of serious adverse effects. The Cancer Genome Atlas is a useful resource to identify novel and more effective targets, which may help to overcome the present limitations. In this review we will discuss the clinical outcome of some of these new therapies with a focus on ovarian and breast cancer. We will also discuss novel concepts in targeted therapy, the target of cancer stem cells.

Room for improvement in breast cancer clinical trial design: taking advantage of the preoperative setting

Achieving approval of new oncologic drugs in breast cancer (BC) is lengthy and costly. After approval in a randomized Phase III trial in metastatic BC, an agent is then evaluated in stage I-III BC. It can take a decade for drug approval in early-stage BC, given the large sample size and long follow-up to detect improvements in disease-free or overall survival. One way to reduce this time period is conducting preoperative trials. In neoadjuvant BC trials, improvements in pathologic complete response in randomized trials of chemotherapy with and without a new agent can lead to accelerated approval. In exploratory investigational new drug trials, such as Phase 0 trials, new drugs can be evaluated for a limited time prior to traditional dose escalation trials. The US FDA has released guidelines for utilization of preoperative trials. The goal is to administer a new agent to the right subset of BC patients quicker and more effectively.

Immunosuppressants in cancer prevention and therapy

Rapalogs such as rapamycin (sirolimus), everolimus, temserolimus, and deforolimus are indicated for the treatment of some malignancies. Rapamycin is the most effective cancer-preventive agent currently known, at least in mice, dramatically delaying carcinogenesis in both normal and cancer-prone murine strains. In addition, rapamycin and everolimus decrease the risk of cancer in patients receiving these drugs in the context of immunosuppressive regimens. In general, the main concern about the use of immunosuppressants in humans is an increased risk of cancer. Given that rapalogs are useful in cancer prevention and therapy, should they be viewed as immunosuppressants or immunostimulators? Or should we reconsider the role of immunity in cancer altogether? In addition to its anti-viral, anti-inflammatory, anti-angiogenic and anti-proliferative effects, rapamycin operates as a gerosuppressant, meaning that it inhibits the cellular conversion to a senescent state (the so-called geroconversion), a fundamental process involved in aging and age-related pathologies including cancer.

Differentiating mTOR inhibitors in renal cell carcinoma

PI3K/Akt/mTOR signalling is dysregulated in many cancers, including renal cell carcinoma (RCC), and activation of this pathway has been suggested to correlate with aggressive behavior and poor prognosis in RCC tumors. mTOR inhibition plays a principal role in the targeted treatment of many cancer types, including RCC. Although mTOR inhibitors share the same mechanism of action, differences in metabolism, formulation and dosing schedule underpin distinct PK/PD profiles such that they may be differentiated for use in a variety of treatment niches. Approved mTOR inhibitors temsirolimus and everolimus serve as important therapeutic options within the current RCC treatment paradigm, although their recommended applications differ in setting and patient population characteristics. Clinical practice guidelines recommend temsirolimus for use in treatment-naive patients with poor-prognosis metastatic RCC of any histology (predominant clear cell or non-clear cell histology). Everolimus provides a standard-of-care therapy for patients with metastatic RCC whose disease has progressed after previous vascular endothelial growth factor receptor-tyrosine kinase inhibitor therapy. As therapeutic failure impacts the vast majority of patients with RCC, sequencing strategies of available agents or simultaneous targeting of multiple members of the PI3K/Akt/mTOR pathway may provide additional clinical benefit. Various classes of agents targeting the PI3K/Akt/mTOR pathway are currently being investigated, including mTORC1/mTORC2 kinase domain inhibitors, mTOR/PI3K dual inhibitors, PI3K-selective inhibitors, and programmed cell death 6 modulators. Clinical trials of mTOR inhibitors in a variety of tumor types are ongoing, and the role of mTOR inhibitors continues to evolve across the RCC treatment landscape.

Health-related quality of life and disease symptoms in postmenopausal women with HR(+), HER2(-) advanced breast cancer treated with everolimus plus exemestane versus exemestane monotherapy

OBJECTIVE

Everolimus (EVE)+exemestane (EXE; n = 485) more than doubled median progression-free survival versus placebo (PBO) + EXE (n = 239), with a manageable safety profile and no deterioration in health-related quality-of-life (HRQOL) in patients with hormone-receptor-positive (HR(+)) advanced breast cancer (ABC) who recurred or progressed on/after nonsteroidal aromatase inhibitor (NSAI) therapy. To further evaluate EVE + EXE impact on disease burden, we conducted additional post-hoc analyses of patient-reported HRQOL.

RESEARCH DESIGN AND METHODS

HRQOL was assessed using EORTC QLQ-C30 and QLQ-BR23 questionnaires at baseline and every 6 weeks thereafter until treatment discontinuation because of disease progression, toxicity, or consent withdrawal. Endpoints included the QLQ-C30 Global Health Status (QL2) scale, the QLQ-BR23 breast symptom (BRBS), and arm symptom (BRAS) scales. Between-group differences in change from baseline were assessed using linear mixed models with selected covariates. Sensitivity analysis using pattern-mixture models determined the effect of study discontinuation on/before week 24. Treatment arms were compared using differences of least squares mean (LSM) changes from baseline and 95% confidence intervals (CIs) at each timepoint and overall.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov: NCT00863655.

MAIN OUTCOME MEASURES

Progression-free survival, survival, response rate, safety, and HRQOL.

RESULTS

Linear mixed models (primary model) demonstrated no statistically significant overall difference between EVE + EXE and PBO + EXE for QL2 (LSM difference = -1.91; 95% CI = -4.61, 0.78), BRBS (LSM difference = -0.18; 95% CI = -1.98, 1.62), or BRAS (LSM difference = -0.42; 95% CI = -2.94, 2.10). Based on pattern-mixture models, patients who dropped out early had worse QL2 decline on both treatments. In the expanded pattern-mixture model, EVE + EXE-treated patients who did not drop out early had stable BRBS and BRAS relative to PBO + EXE.

KEY LIMITATIONS

HRQOL data were not collected after disease progression.

CONCLUSIONS

These analyses confirm that EVE + EXE provides clinical benefit without adversely impacting HRQOL in patients with HR(+) ABC who recurred/progressed on prior NSAIs versus endocrine therapy alone.

Primary therapy in breast cancer: what have we learned from landmark trials?

Primary anticancer therapy is currently accepted as a therapeutic option for patients with early-stage breast cancer. Its objectives are to increase the chance of achieving a conservative surgery and, similar to adjuvant chemotherapy, to reduce the risk of distant recurrence. The prognostic significance of obtaining a pathological complete response has been evaluated in several randomized clinical trials and meta-analyses. Growing evidence suggests that pathological complete response may act as a valid predictor of overall survival. Of note, a significant association between pathological complete response and outcome has especially been observed in patients with HER2-positive and triple-negative (hormonal receptors negative and HER2-negative) breast cancer. This review focuses on recent trials of neoadjuvant treatment with specific attention to HER2-negative disease.

Tumour hypoxia determines the potential of combining mTOR and autophagy inhibitors to treat mammary tumours

BACKGROUND

Hypoxia can activate autophagy, a self-digest adaptive process that maintains cell turnover. Mammalian target of rapamycin (mTOR) inhibitors are used to treat cancer but also stimulate autophagy.

METHODS

Human mammary cancer cells and derived xenografts were used to examine whether hypoxia could exacerbate autophagy-mediated resistance to the mTOR inhibitor rapamycin.

RESULTS

Rapamycin exerted potent antitumour effects in MCF-7 and MDA-MB-231 mammary tumours through a marked inhibition of angiogenesis, but the autophagy inhibitor chloroquine (CQ) failed to further sensitise tumours to mTOR inhibition. Rapamycin treatment actually led to tumour reoxygenation, thereby preventing the development of autophagy. Chloroquine alone, however, blocked the growth of MCF-7 tumours and in vitro blunted the hypoxia-induced component of autophagy in these cells. Finally, when initiating CQ treatment in large, hypoxic tumours, a robust antitumour effect could be observed, which also further increased the antiproliferative effects of rapamycin.

CONCLUSION

The mTOR inhibitor rapamycin significantly contributes to tumour growth inhibition and normalisation of the tumour vasculature through potent antiangiogenic effects. The resulting reduction in hypoxia accounts for a lack of sensitisation by the autophagy inhibitor CQ, except if the tumours are already at an advanced stage, and thus largely hypoxic at the initiation of the combination of rapamycin and CQ treatment.

Everolimus plus exemestane in postmenopausal patients with HR(+) breast cancer: BOLERO-2 final progression-free survival analysis

Introduction

Effective treatments for hormone-receptor-positive (HR⁺) breast cancer (BC) following relapse/progression on nonsteroidal aromatase inhibitor (NSAI) therapy are needed. Initial Breast Cancer Trials of OraL EveROlimus-2 (BOLERO-2) trial data demonstrated that everolimus and exemestane significantly prolonged progression-free survival (PFS) versus placebo plus exemestane alone in this patient population.

Methods

BOLERO-2 is a phase 3, double-blind, randomized, international trial comparing everolimus (10 mg/day) plus exemestane (25 mg/day) versus placebo plus exemestane in postmenopausal women with HR⁺ advanced BC with recurrence/progression during or after NSAIs. The primary endpoint was PFS by local investigator review, and was confirmed by independent central radiology review. Overall survival, response rate, and clinical benefit rate were secondary endpoints.

Results

Final study results with median 18-month follow-up show that median PFS remained significantly longer with everolimus plus exemestane versus placebo plus exemestane [investigator review: 7.8 versus 3.2 months, respectively; hazard ratio = 0.45 (95% confidence interval 0.38–0.54); log-rank P < 0.0001; central review: 11.0 versus 4.1 months, respectively; hazard ratio = 0.38 (95% confidence interval 0.31–0.48); log-rank P < 0.0001] in the overall population and in all prospectively defined subgroups, including patients with visceral metastases, patients with recurrence during or within 12 months of completion of adjuvant therapy, and irrespective of age. The incidence and severity of adverse events were consistent with those reported at the interim analysis and in other everolimus trials.

Conclusion

The addition of everolimus to exemestane markedly prolonged PFS in patients with HR⁺ advanced BC with disease recurrence/progression following prior NSAIs. These results further support the use of everolimus plus exemestane in this patient population. ClinicalTrials.gov #NCT00863655.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-013-0060-1) contains supplementary material, which is available to authorized users.

PIK3CA and AKT1 mutations have distinct effects on sensitivity to targeted pathway inhibitors in an isogenic luminal breast cancer model system

PURPOSE

Activating mutations in the phosphoinositide-3-kinase (PI3K)/AKT/mTOR pathway are present in the majority of breast cancers and therefore are a major focus of drug development and clinical trials. Pathway mutations have been proposed as predictive biomarkers for efficacy of PI3K-targeted therapies. However, the precise contribution of distinct PI3K pathway mutations to drug sensitivity is unknown.

EXPERIMENTAL DESIGN

We describe the creation of a physiologic human luminal breast cancer cell line model to study the phenotype of these mutations using the MCF-7 cell line. We used somatic cell gene targeting to "correct" PIK3CA E545K-mutant alleles in MCF-7 cells to wild-type sequence. The AKT1 E17K hotspot mutation was knocked in on this wild-type background.

RESULTS

Loss of mutant PIK3CA dramatically reduced phosphorylation of AKT proteins and several known AKT targets, but other AKT target proteins and downstream effectors of mTOR were not affected. PIK3CA wild-type cells exhibited reduced proliferation in vitro and in vivo. Knockin of the AKT1 E17K hotspot mutation on this PIK3CA wild-type background restored pathway signaling, proliferation, and tumor growth in vivo. PIK3CA, but not AKT1 mutation, increased sensitivity to the PI3K inhibitor GDC-0941 and the allosteric AKT inhibitor MK-2206.

CONCLUSIONS

AKT1 E17K is a bona fide oncogene in a human luminal breast cancer context. Distinct PI3K pathway mutations confer differential sensitivity to drugs targeting the pathway at different points and by distinct mechanisms. These findings have implications for the use of tumor genome sequencing to assign patients to targeted therapies.

Everolimus for compassionate use in multiple Basal cell carcinomas

Everolimus is an inhibitor of the mammalian target of rapamycin (mTOR) and has been shown to have antineoplastic activity in addition to its use as an immunosuppressive agent for the prevention of organ transplant rejection. We report the use of everolimus for the compassionate treatment of four elderly, nontransplant patients presenting with multiple basal cell carcinomas (BCC). All patients had a long history of BCC, had refused surgery as a current treatment option, and did not respond to alternative treatments (including topical 5-fluorouracil and imiquimod). Patients were treated with oral everolimus (1.5-3.0 mg daily) for 12 months or longer: a complete and sustained response was seen in one case, and partial responses were seen in two other cases. Everolimus was well tolerated in these elderly patients. These promising preliminary data suggest that further dose-finding, controlled clinical studies are warranted to evaluate the antineoplastic effects of everolimus in patients affected by BCC who cannot or will not undergo surgery.

Emerging targeted combinations in the management of breast cancer

The number of targeted treatments has risen exponentially over the last few years and is an important concept in the fight against cancer. This review will concentrate on some of the main treatments targeting aberrant pathways which have been tested mainly in the Phase I/II setting. These include human epidermal growth factor receptor 2 inhibitors, drug-antibody conjugates, epidermal growth factor receptor inhibitors, vascular endothelial growth factor inhibitors, reticular activating system, mammalian target of rapamycin and multi-kinase inhibitors. Further knowledge of these pathways and the predictors of response to them will enable personalized medicine to become a reality.

Everolimus: side effect profile and management of toxicities in breast cancer

Everolimus is an orally available inhibitor of the mammalian target of rapamycin (mTOR), which has been approved in combination with exemestane for hormone receptor-positive (HR) breast cancer after failure of treatment with non-steroidal aromatase inhibitors. Everolimus is generally very well tolerated with most common side effects including stomatitis, rash, fatigue, hyperglycemia, hyperlipidemia, and myelosuppression. Most of these side effects are mild and resolve with dose interruptions or dose reductions. Symptomatic non-infectious pneumonitis is a relatively uncommon class effect of mTOR inhibitors, which can be life threatening. Given the efficacy of everolimus in HR-positive metastatic breast cancer, it is crucial for physicians to recognize toxicities related to everolimus and start timely interventions. This review will focus on the adverse events reported with everolimus in breast cancer trials and will provide practical guidelines for the management of these adverse events.

Endocrine therapy: is the first generation of targeted drugs the last?

Hormonal therapy for breast cancer is the first targeted therapy used in any type of cancer. It was used successfully without a known target for more than 50 years before Jensen described the oestrogen receptor (ER) in the 1960s. Subsequently, it was found that endocrine therapy was effective only in those patients whose tumours expressed the ER; more recently, it has been recognized that this therapy can also be effective in some patients whose tumours are ERα-negative but ERβ-positive. However, in spite of the ER being present, many tumours develop either primary or secondary resistance to various endocrine approaches. ER-containing tumours may also be classified by molecular markers as luminal A (highly hormone responsive) or luminal B (high degree of proliferation and less hormone responsiveness). Furthermore, the expression of ER, progesterone receptor and human epidermal growth factor receptor 2 (HER2) may change over time as tumours metastasize and progress. The addition of anti-HER2 agents such as trastuzumab and lapatinib to hormonal therapies has improved outcomes but it is unclear whether these approaches are additive or synergistic. Now, mammalian target of rapamycin (mTOR) inhibitors are being successfully used in similar scenarios but once again it is unclear whether the effect of this combination therapy is synergistic; however, mTOR inhibitors produce little response as single agents. In particular, the addition of the mTOR inhibitor everolimus has improved disease-free and overall survival in randomized studies in metastatic disease when added either to an aromatase inhibitor or to tamoxifen. To date, however, no specific biomarkers for the use of everolimus have been reported. Further studies are needed to identify and validate targets of therapy in endocrine-responsive breast cancer.

Luminal breast cancer: from biology to treatment

Oestrogen receptor (ER)-positive--or luminal--tumours represent around two-thirds of all breast cancers. Luminal breast cancer is a highly heterogeneous disease comprising different histologies, gene-expression profiles and mutational patterns, with very varied clinical courses and responses to systemic treatment. Despite adjuvant endocrine therapy and chemotherapy treatment for patients at high risk of relapse, both early and late relapses still occur, a fact that highlights the unmet medical needs of these patients. Ongoing research aims to identify those patients who can be spared adjuvant chemotherapy and who will benefit from extended adjuvant hormone therapy. This research also aims to explore the role of adjuvant bisphosphonates, to interrogate new agents for targeting minimal residual disease, and to address endocrine resistance. Data from next-generation sequencing studies have given us new insight into the biology of luminal breast cancer and, together with advances in preclinical models and the availability of newer targeted agents, have led to the testing of rationally chosen combination treatments in clinical trials. However, a major challenge will be to make sense of the large amount of patient genomic data that is becoming increasingly available. This analysis will be critical to our understanding how intertumour and intratumour heterogeneity can influence treatment response and resistance.

Pulmonary complications with the use of mTOR inhibitors in targeted cancer therapy: a systematic review and meta-analysis

Mammalian target of rapamycin (mTOR) inhibitors have gained regulatory approval for use in several cancer types. Pulmonary adverse events associated with mTOR inhibitors are well recognized but their frequency has varied considerably among trials. PubMed and ASCO abstracts were searched to identify clinical trials of mTOR inhibitors in solid tumors. Twenty-two eligible trials on which 4,242 patients were treated met the criteria for inclusion in this systematic review and meta-analysis. Adverse event data were extracted and used to determine the incidence rate and incidence rate ratio for pneumonitis, dyspnea, and cough. The incidence rate of any grade pneumonitis in patients with solid tumors treated with mTOR inhibitors was 0.11 (95% confidence interval (CI), 0.06-0.17) per patient, while the incidence of grade 3-4 pneumonitis was 0.03 (95% CI, 0.01-0.04) per patient. The incidence rate ratio (IRR) of any grade pneumonitis with mTOR inhibitors relative to controls was 19.0 (95% CI, 6.5-55.4), and for grade 3-4 pneumonitis was 8.0 (95% CI, 2.6-24.1). The incidence rate for any grade and grade 3-4 cough was 0.23 (95% CI, 0.20-0.27) per patient and 0.01 (95% CI, 0.00-0.01) per patient, respectively. The incidence rate for any grade and grade 3-4 dyspnea was 0.15 (95% CI, 0.10-0.21) per patient and 0.03 (95% CI, 0.02-0.04) per patient, respectively. Compared to control, treatment with mTOR inhibitors were associated with a significant increase in any grade cough [IRR = 1.9 (95% CI, 1.6-2.4)] and grade 3-4 dyspnea [IRR = 2.0 (95% CI, 1.2-3.3)]. This study provides an estimation of the risk of pulmonary adverse events in solid tumor patients treated with mTOR inhibitors. While pulmonary adverse events are relatively common with mTOR inhibitors, most are low grade and asymptomatic.

mTOR signaling for biological control and cancer

Mammalian target of rapamycin (mTOR) is a major intersection that connects signals from the extracellular milieu to corresponding changes in intracellular processes. When abnormally regulated, the mTOR signaling pathway is implicated in a wide spectrum of cancers, neurological diseases, and proliferative disorders. Therefore, pharmacological agents that restore the regulatory balance of the mTOR pathway could be beneficial for a great number of diseases. This review summarizes current understanding of mTOR signaling and some unanswered questions in the field. We describe the composition of the mTOR complexes, upstream signals that activate mTOR, and physiological processes that mTOR regulates. We also discuss the role of mTOR and its downstream effectors in cancer, obesity and diabetes, and autism.

Tailoring adjuvant treatments for the individual patient with luminal breast cancer

Estrogen Receptor-positive/HER-2 negative breast cancers represent a heterogeneous group of tumors. Luminal A and B tumor subtypes can be identified through immunohistochemical assessment of estrogen and progesterone receptor, Ki-67 and HER-2 status. Patients with high levels of expression of steroid hormone receptors and low proliferation (Luminal A) are commonly cured with endocrine therapy alone. Patients with doubtful endocrine responsiveness or with high proliferation index (Luminal B/Her-negative) require the addition of chemotherapy to the best endocrine therapy. Controversies still exist on the identification of those patients who do not benefit from chemotherapy. Tailored adjuvant treatments should be considered in the therapeutic algorithm of patients with luminal tumors.

Incidence and risk of treatment-related mortality with mTOR inhibitors everolimus and temsirolimus in cancer patients: a meta-analysis

Background

Two novel mammalian targets of rapamycin (mTOR) inhibitors everolimus and temsirolimus are now approved by regulatory agencies and have been widely investigated among various types of solid tumors, but the risk of fatal adverse events (FAEs) with these drugs is not well defined.

Methods

We searched PubMed, EMBASE, and Cochrane library databases for relevant trials. Eligible studies included prospective phase II and III trials evaluating everolimus and temsirolimus in patients with all malignancies and data on FAEs were available. Statistical analyses were conducted to calculate the summary incidence, RRs and 95% confidence intervals (CIs) by using either random effects or fixed effect models according to the heterogeneity of the included studies.

Results

A total of 3322 patients with various advanced solid tumors from 12 trials were included. The overall incidence of mTOR inhibitors associated FAEs was 1.8% (95%CI: 1.3–2.5%), and the incidences of everolimus related FAEs were comparable to that of temsirolimus (1.7% versus 1.8%). Compared with the controls, the use of mTOR inhibitors was associated with an increased risk of FAEs, with a RR of 3.24 (95%CI: 1.21–8.67, p = 0.019). On subgroup analysis, a non-statistically significant increase in the risk of FAEs was found according to different mTOR inhibitors, tumor types or controlled therapy. No evidence of publication bias was observed.

Conclusion

With the present evidence, the use of mTOR inhibitors seems to increase the risk of FAEs in patients with advanced solid tumors. More high quality trials are still needed to investigate this association.