Everolimus plus octreotide long-acting repeatable for the treatment of advanced neuroendocrine tumours associated with carcinoid syndrome (RADIANT-2): a randomised, placebo-controlled, phase 3 study

[Advanced research of mTOR and lung carcinoid tumors]

Mammalian target of rapamycin (mTOR), a main protein kinase in the phosphoinositide 3-kinase (PI3K)/AKT/mTOR signaling pathway, is an important intracellular mediator involved in multiple celluar functions including proliferation, differentiation, apoptosis, tumorigenesis, and angiogenesis. Recently, the high expression of mTOR and mTOR-related kinase have been found in neuroendocrin tumors. Therefore, mTOR pathway represents an attractive target for new anticancer therapies except surgery.

Improving the diagnosis and management of neuroendocrine tumors: utilizing new advances in biomarker and molecular imaging science

Neuroendocrine tumors (NET) are malignant solid tumors that arise in hormone-secreting tissue of the diffuse neuroendocrine system or endocrine glands. Although traditionally understood to be a rare disease, the incidence and prevalence of NET have increased greatly in the past 3 decades. However, during this time, progress in diagnosis and outcome of NET has generally been modest. In order to achieve improved outcome in NET, a better understanding of NET biology combined with more reliable serum markers and better techniques to identify tumor localization and small lesions are needed. Although some NET biomarkers exist, sensitive and specific markers that predict tumor growth and behavior are generally lacking. In addition, the integration of new molecular imaging technologies in patient diagnosis and follow-up has the potential to enhance care. To discuss developments and issues required to improve diagnostics and management of NET patients, with specific focus on the latest advances in molecular imaging and biomarker science, 17 global leaders in the fields of NET, molecular imaging and biomarker technology gathered to participate in a 2-day meeting hosted by Prof. Kjell Öberg at the University of Uppsala in Sweden. During this time, findings were presented regarding methods with potential prognostic and treatment applications in NET or other types of cancers. This paper describes the symposium presentations and resulting discussions.

Treatment of metastatic neuroendocrine tumors of the thymus with capecitabine and temozolomide: a case series

BACKGROUND

Metastatic neuroendocrine tumors of the thymus are exceedingly rare with an annual incidence of approximately 0.2 per 1,000,000. They are highly resistant to therapy and there have been no reports of an objective radiographic response to treatment.

MATERIALS AND METHODS

The authors retrospectively evaluated 3 patients with progressive, metastatic neuroendocrine tumors of the thymus who were treated with a combination of capecitabine and temozolomide. Radiographic scans were evaluated and response assessed using RECIST criteria.

RESULTS

One patient experienced a partial radiographic response, another patient experienced a minor response and the third patient experienced stable disease as the best response to treatment.

CONCLUSION

The combination of capecitabine and temozolomide appears to be active in a rare neuroendocrine malignancy that is generally refractory to systemic therapy. Prospective multicenter trials are needed to validate this strategy.

Translation of molecular pathways into clinical trials of neuroendocrine tumors

Current treatment options for neuroendocrine tumors (NET) include somatostatin analogs, interferon-α, peptide receptor-targeted therapy and cytotoxic chemotherapy. Most patients undergo sequential therapies since these drugs are active only in subpopulations of patients and for a limited period of time. There is a need for novel drugs that are capable of amelioration of symptomatology (syndromic control) and/or tumor growth control. A number of diverse signaling pathways are involved in the pathogenesis of NET and tumor growth, thus many potential targets are available for drug targeting. Targeted therapies therefore represent an appropriate developmental therapeutic strategy given the multiplicity of potential targets in NET. These include but are not limited to: inhibitory or activating G protein-coupled receptors, receptor tyrosine kinases, ligands, and intracellular targets such as the mammalian target of rapamycin (mTOR). Numerous drugs that utilize single or multiple targets are currently in clinical development. Recently, two target-directed agents, the multiple tyrosine kinase inhibitor sunitinib and the mTOR inhibitor everolimus, have been approved for the treatment of progressive pancreatic NET. This review provides a broad overview of established and potential molecular targets in NET, summarizes data from phase II and III clinical trials with targeted drugs and outlines future therapeutic directions.

Targeting LKB1 signaling in cancer

The serine/threonine kinase LKB1 is a master kinase involved in cellular responses such as energy metabolism, cell polarity and cell growth. LKB1 regulates these crucial cellular responses mainly via AMPK/mTOR signaling. Germ-line mutations in LKB1 are associated with the predisposition of the Peutz-Jeghers syndrome in which patients develop gastrointestinal hamartomas and have an enormously increased risk for developing gastrointestinal, breast and gynecological cancers. In addition, somatic inactivation of LKB1 has been associated with sporadic cancers such as lung cancer. The exact mechanisms of LKB1-mediated tumor suppression remain so far unidentified; however, the inability to activate AMPK and the resulting mTOR hyperactivation has been detected in PJS-associated lesions. Therefore, targeting LKB1 in cancer is now mainly focusing on the activation of AMPK and inactivation of mTOR. Preclinical in vitro and in vivo studies show encouraging results regarding these approaches, which have even progressed to the initiation of a few clinical trials. In this review, we describe the functions, regulation and downstream signaling of LKB1, and its role in hereditary and sporadic cancers. In addition, we provide an overview of several AMPK activators, mTOR inhibitors and additional mechanisms to target LKB1 signaling, and describe the effect of these compounds on cancer cells. Overall, we will explain the current strategies attempting to find a way of treating LKB1-associated cancer.

Everolimus plus octreotide long-acting repeatable in patients with colorectal neuroendocrine tumors: a subgroup analysis of the phase III RADIANT-2 study

INTRODUCTION

The incidence of colorectal neuroendocrine tumors (NETs) is increasing, and patients with this disease have particularly poor prognoses. Treatment options are limited, and survival times have not improved in the past decade.

METHODS

A post hoc analysis of the efficacy and tolerability of everolimus plus octreotide long-acting repeatable (LAR) was conducted in patients with colorectal NETs enrolled in the phase III RAD001 in Advanced Neuroendocrine Tumors, Second Trial (RADIANT-2) study. The primary endpoint (progression-free survival [PFS]), secondary endpoints (including objective response rate), and safety were assessed.

RESULTS

Patients with colorectal NETs receiving everolimus plus octreotide LAR had a significantly longer median PFS (29.9 months; n = 19) than did those receiving placebo plus octreotide LAR (6.6 months; n = 20). Everolimus plus octreotide LAR treatment also significantly reduced the risk for disease progression (hazard ratio: 0.34; 95% confidence interval: 0.13-0.89; p = .011). Although no objective responses were observed, tumor shrinkage was more frequently noted in the everolimus plus octreotide LAR arm than in the placebo plus octreotide LAR arm (67% vs. 37%, respectively). The combination of everolimus plus octreotide LAR was generally well tolerated by patients with colorectal NETs; rash and stomatitis were the most commonly reported adverse events.

CONCLUSIONS

Everolimus plus octreotide LAR treatment had significant benefits and improved outcomes for patients with advanced colorectal NETs compared with placebo plus octreotide LAR treatment. Results of this exploratory analysis are consistent with those reported from the RADIANT-2 primary analysis. These findings support additional investigations of everolimus plus octreotide LAR in patients with colorectal NETs.

Novel molecular targets for the treatment of gastroenteropancreatic endocrine tumors: answers and unsolved problems

As more knowledge on molecular alterations favoring carcinogenesis and spreading of gastroenteropancreatic endocrine tumors has become available, a number of targeted agents interfering with key growth and angiogenic pathways have been explored in preclinical and clinical studies. The mTOR inhibitor Everolimus, and the multi-target antiangiogenetic agent Sunitinib, have been shown to be effective and thus have been approved by the FDA for treatment of pancreatic endocrine tumors. However, there is little data on the primary resistance to targeted agents on these tumors. The goals of the present review are to elucidate the possible advantage of combined treatments in overcoming induced resistances, and to identify biomarkers able to predict clinical efficacy. Moreover, the role of interesting targets for which a strong biological rationale exists, and specific inhibitors are available, such as the Src Family Kinases and the Hedgehog Pathway, are discussed. There is now need for more preclinical studies on cell lines and animal models to provide a stronger preclinical background in this field, as well as clinical trials specifically comparing one targeted therapy with another or combining different targeted agents.

mTOR: on target for novel therapeutic strategies in the nervous system

The mammalian target of rapamycin (mTOR), the key component of the protein complexes mTORC1 and mTORC2, plays a critical role in cellular development, tissue regeneration, and repair. mTOR signaling can govern not only stem cell development and quiescence but also cell death during apoptosis or autophagy. Recent studies highlight the importance of both traditional and newly recognized interactors of mTOR, such as p70S6K, 4EBP1, GSK-3β, REDD1/RTP801, TSC1/TSC2, growth factors, wingless, and forkhead transcription factors, that influence Alzheimer's disease, Parkinson's disease, Huntington's disease, tuberous sclerosis, and epilepsy. Targeting mTOR in the nervous system can offer exciting new avenues of drug discovery, but crucial to this premise is elucidating the complexity of mTOR signaling for robust and safe clinical outcomes.

Colonic and rectal NET's

Neuroendocrine tumours of the Colon and Rectum are rare but are increasing in incidence as a result of greater investigation with endoscopy and improved histological reporting. Classification with the 2010 WHO TNM staging system as well as grading based on the Ki-67 index has led to improved prognostic assessment. The use of Endoanal Ultrasound has increased the sensitivity of detection of depth of invasion and lymphovascular involvement, which is associated with a poor prognosis. Standard polypectomy has largely been replaced by endoscopic mucosal resection of smaller polyps, although newer techniques such as band ligation or endoscopic submucosal dissection are likely to be associated with less residual disease. The management of advanced disease remains a challenge but new treatments such as Peptide Receptor Targeted therapy and molecular targeted treatments offer hope of improved progression free survival in non-resectable disease.

Neuroendocrine tumours of the small intestine

The prevalence of intestinal neuroendocrine tumours, also known as carcinoid tumours, has increased significantly over the past three decades. Tumours of the distal small intestine (midgut) are often indolent, but are characterized by a high potential to metastasize to the small-bowel mesentery and liver. Patients with distant metastases are prone to development of the carcinoid syndrome, a constellation of symptoms which includes flushing, diarrhoea, and valvular heart disease. The carcinoid syndrome is caused by secretion of serotonin and other vasoactive substances into the systemic circulation. Treatment options for metastatic intestinal NETs have expanded in recent years. Of particular importance has been the development of somatostatin-analogue therapies. Somatostatin analogues were originally introduced for palliation of the carcinoid syndrome; however recent clinical trials have demonstrated that they can exert an inhibitory effect on tumour growth. Other novel agents targeting the VEGF and mTOR pathways have recently been evaluated in phase III trials, however their role in the management of small-intestinal NETs remains controversial. This article examines the biological characteristics of small intestinal NETs, summarizes current guidelines on classification, staging and grading, and reviews developments in locoregional and systemic therapy.

Intervention in gastro-enteropancreatic neuroendocrine tumours

Neuroendocrine tumours require dedicated interventions to control their capacity to secrete hormones but also, antitumour growth strategies. Recommendations for early interventions in NET include the management of hormone-related symptoms and poorly differentiated neuroendocrine carcinomas. In contrast, prognostic heterogeneity is a key feature of well differentiated NET that complexified the antitumour strategy whatever the stage in this subgroup of tumour. In this review, timely therapeutic interventions to control hormone-related symptoms and tumour growth in GEP NET patients are discussed. The necessity of controlling hormone-related symptoms as the first step of any strategy affects also the tumour growth control strategy. In the absence of cure at the metastatic stage, progresses are expected in the recognition of well differentiated NET subgroups that display either excellent or poor prognosis.

Selecting patients for cytotoxic therapies in gastroenteropancreatic neuroendocrine tumours

Gastroenteropancreatic neuroendocrine tumours (GEP-NET) have heterogenic clinical presentations. The majority of GEP-NET tumours have an indolent behaviour, but patients will eventually develop symptoms of tumour progression or hormone secretion that may require systemic medical interventions. Cytotoxic chemotherapy has been tested in GEP-NETs since the 80s, but treatment recommendations are controversial in many instances. Patient selection is mandatory for optimal use of chemotherapy. Important prognostic factors such as primary tumour site, tumour differentiation, tumour staging and proliferation index have been identified and validated in retrospective and prospective series. The combination of those factors and the natural history of GEP-NET provide valuable information with respect to treatment planning. In this report we provide treatment recommendations to improve systemic therapy in patients with advanced GEP-NETs based on a comprehensive review of the literature.

Outcome of surgery for ileojejunal neuroendocrine tumors

PURPOSE

Neuroendocrine tumors (NET) of the ileum/jejunum are rare and may require different treatment options to provide long-term survival. The purpose of the study was to evaluate the outcome of surgery for ileojejunal NET.

METHODS

A database of patients that underwent surgery for ileojejunal NETs between 1999 and 2010 was retrospectively analyzed regarding the clinical characteristics, surgical therapy, survival and prognostic factors.

RESULTS

Only six of 97 patients with ileojejunal NET who underwent surgery had localized tumors (stage I/II), 29 had lymph node involvement (stage III) and 62 had distant metastases (stage IV) at the initial presentation. All stage I/II tumors were cured, in comparison to 69% of stage III and 0% of stage IV tumors (p = 0.01). Palliative surgery in combination with sequential multimodal treatment regimens resulted in a 5-year survival rate of 63% in patients with stage IV tumors. A multivariate analysis showed that incomplete resection (HR 2.87; CI 1.18-6.98; p = 0.04) and distant metastases (HR 5.39; 95% CI 1.23-23.57; p = 0.02) were associated with worse disease-specific survival.

CONCLUSIONS

Localized and regionally restricted ileojejunal NETs have an excellent prognosis after surgical treatment. Although stage IV tumors cannot be cured, an aggressive surgical approach in combination with medical or interventional treatment can provide long-term survival.

A Critical Kinase Cascade in Neurological Disorders: PI 3-K, Akt, and mTOR

Neurodegenerative disorders lead to disability and death in a significant proportion of the world's population. However, many disorders of the nervous system remain with limited effective treatments. Kinase pathways in the nervous system that involve phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), and the mammalian target of rapamycin (mTOR) offer exciting prospects for the understanding of neurodegenerative pathways and the development of new avenues of treatment. PI 3-K, Akt, and mTOR pathways are vital cellular components that determine cell fate during acute and chronic disorders, such as Huntington's disease, Alzheimer's disease, Parkinson's disease, epilepsy, stroke, and trauma. Yet, the elaborate relationship among these kinases and the variable control of apoptosis and autophagy can lead to unanticipated biological and clinical outcomes. Crucial for the successful translation of PI 3-K, Akt, and mTOR into robust and safe clinical strategies will be the further elucidation of the complex roles that these kinase pathways hold in the nervous system.

New drugs in the therapy of neuroendocrine tumors

Neuroendocrine tumors (NET) are a rare and heterogeneous group of neoplasms of a relatively indolent nature whose incidence and prevalence are increasing. Despite the advances made in the field of NET over the past years, these tumors eventually progress to metastatic disease in most of the patients, with a fatal outcome in the majority. Traditional cytotoxic agents remain of limited efficacy; however, recently, a better understanding of molecular pathways has provided clues to potential molecular targets for new therapeutic strategies. Somatostatin analogs are well known to be useful for the control of symptoms in functioning tumors, and it was recently demonstrated that they can inhibit tumor progression in certain disease settings. Moreover, the recently published randomized trials with the multi-TKI sunitinib and with the mTOR-inhibitor everolimus have demonstrated, for the first time, their ability to positively impact the natural history of pancreatic NET (PNET). In this short review, we will discuss available data on newer molecular targeted agents for the treatment of advanced well-differentiated gastro-entero- pancreatic NET (GEP-NET). A possible algorithm for the use of these treatments in the context of the extreme heterogeneity of GEP-NET presentation will be proposed.

Shedding new light on neurodegenerative diseases through the mammalian target of rapamycin

Neurodegenerative disorders affect a significant portion of the world's population leading to either disability or death for almost 30 million individuals worldwide. One novel therapeutic target that may offer promise for multiple disease entities that involve Alzheimer's disease, Parkinson's disease, epilepsy, trauma, stroke, and tumors of the nervous system is the mammalian target of rapamycin (mTOR). mTOR signaling is dependent upon the mTORC1 and mTORC2 complexes that are composed of mTOR and several regulatory proteins including the tuberous sclerosis complex (TSC1, hamartin/TSC2, tuberin). Through a number of integrated cell signaling pathways that involve those of mTORC1 and mTORC2 as well as more novel signaling tied to cytokines, Wnt, and forkhead, mTOR can foster stem cellular proliferation, tissue repair and longevity, and synaptic growth by modulating mechanisms that foster both apoptosis and autophagy. Yet, mTOR through its proliferative capacity may sometimes be detrimental to central nervous system recovery and even promote tumorigenesis. Further knowledge of mTOR and the critical pathways governed by this serine/threonine protein kinase can bring new light for neurodegeneration and other related diseases that currently require new and robust treatments.

The somatostatin analogue octreotide inhibits growth of small intestine neuroendocrine tumour cells

Octreotide is a widely used synthetic somatostatin analogue that significantly improves the management of neuroendocrine tumours (NETs). Octreotide acts through somatostatin receptors (SSTRs). However, the molecular mechanisms leading to successful disease control or symptom management, especially when SSTRs levels are low, are largely unknown. We provide novel insights into how octreotide controls NET cells. CNDT2.5 cells were treated from 1 day up to 16 months with octreotide and then were profiled using Affymetrix microarray analysis. Quantitative real-time PCR and western blot analyses were used to validate microarray profiling in silico data. WST-1 cell proliferation assay was applied to evaluate cell growth of CNDT2.5 cells in the presence or absence of 1 µM octreotide at different time points. Moreover, laser capture microdissected tumour cells and paraffin embedded tissue slides from SI-NETs at different stages of disease were used to identify transcriptional and translational expression. Microarrays analyses did not reveal relevant changes in SSTR expression levels. Unexpectedly, six novel genes were found to be upregulated by octreotide: annexin A1 (ANXA1), rho GTPase-activating protein 18 (ARHGAP18), epithelial membrane protein 1 (EMP1), growth/differentiation factor 15 (GDF15), TGF-beta type II receptor (TGFBR2) and tumour necrosis factor (ligand) superfamily member 15 (TNFSF15). Furthermore, these novel genes were expressed in tumour tissues at transcript and protein levels. We suggest that octreotide may use a potential novel framework to exert its beneficial effect as a drug and to convey its action on neuroendocrine cells. Thus, six novel genes may regulate cell growth and differentiation in normal and tumour neuroendocrine cells and have a role in a novel octreotide mechanism system.

Oxidant stress and signal transduction in the nervous system with the PI 3-K, Akt, and mTOR cascade

Oxidative stress impacts multiple systems of the body and can lead to some of the most devastating consequences in the nervous system especially during aging. Both acute and chronic neurodegenerative disorders such as diabetes mellitus, cerebral ischemia, trauma, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and tuberous sclerosis through programmed cell death pathways of apoptosis and autophagy can be the result of oxidant stress. Novel therapeutic avenues that focus upon the phosphoinositide 3-kinase (PI 3-K), Akt (protein kinase B), and the mammalian target of rapamycin (mTOR) cascade and related pathways offer exciting prospects to address the onset and potential reversal of neurodegenerative disorders. Effective clinical translation of these pathways into robust therapeutic strategies requires intimate knowledge of the complexity of these pathways and the ability of this cascade to influence biological outcome that can vary among disorders of the nervous system.

Phase I-II study of radiopeptide 177Lu-octreotate in combination with capecitabine and temozolomide in advanced low-grade neuroendocrine tumors

Abstract We conducted a phase I-II clinical trial to assess the safety and efficacy of combining lutetium-177 ((177)Lu)-octreotate with capecitabine and temozolomide in treating advanced low-grade neuroendocrine tumors (NETs). All 35 patients received fixed activities of 7.8 GBq (177)Lu-octreotate each 8 weeks, with 14 days of capecitabine 1500 mg/m(2) for 4 cycles. In phase I, successive cohorts of patients received escalating doses of temozolomide in groupings of 100, 150, and 200 mg/m(2) in the last 5 days of each capecitabine cycle. In phase II, patients were treated with 200 mg/m(2) temozolomide. Treatment was well tolerated in all dosage groups. No dose-limiting grade 2, 3, or 4 toxicities were seen in cohorts 1 (100 mg/m(2)) or 2 (150 mg/m(2)). Twenty-eight patients completed treatment at the 200 mg/m(2) temozolomide level. Adverse events were mild to moderate. The commonest toxicities were transient nausea grade 2 (18%), grade 3 (3%), thrombocytopenia grade 2 (24%), and neutropenia grade 3 (6%). There were no grade 4 events. Thirty-four patients were evaluable for tumor response. Overall, complete response (CR) was achieved in 15% (95% CI 3-27); partial response (PR), in 38% (95% CI 22-55); stable disease (SD), in 38% (95% CI 22-55); and 3 patients failed to respond to treatment. Median progression free survival (PFS) was 31 months (95% CI 21-33), and median overall survival (OS) has not been reached with 90% surviving at 24 months follow-up (range 21-30). Overall objective response rate (ORR) in patients with gastroenteropancreatic NETs showed CR 16% (95% CI 3-28), PR 41% (95% CI 24-58), SD 37% (95% CI 21-54), and PD 6% (95% CI 0-15). Response rates were higher in patients with gastropancreatic NETs than in those with bowel primaries (enteric-NETs); CR 18% versus 13%, PR 64% versus 13%, SD 12% versus 67%. (177)Lu-octreotate, in combination with capecitabine and temozolomide, is well tolerated in patients with advanced low-grade NETs, and shows substantial tumor control rates.

Risk of de novo cancers after transplantation: results from a cohort of 7217 kidney transplant recipients, Italy 1997-2009

To assess incidence and risk factors for de novo cancers (DNCs) after kidney transplant (KT), we carried out a cohort investigation in 15 Italian KT centres. Seven thousand two-hundred seventeen KT recipients (64.2% men), transplanted between 1997 and 2007 and followed-up until 2009, represented the study group. Person years (PY) were computed from 30 days after transplant to cancer diagnosis, death, return to dialysis or to study closure. The number of observed DNCs was compared to that expected in the general population of Italy through standardised incidence ratios (SIR) and 95% confidence intervals (CI). To identify risk factors, incidence rate ratios (IRR) were computed. Three-hundred ninety five DNCs were diagnosed during 39.598PYs, with Kaposi's sarcoma (KS), post-transplant lymphoproliferative disorders (PTLD), particularly non-Hodgkin' lymphoma (NHL), lung, kidney and prostate as the most common types. The overall IR was 9.98/1.000PY, with a 1.7-fold augmented SIR (95% CI: 1.6-1.9). SIRs were particularly elevated for KS (135), lip (9.4), kidney carcinoma (4.9), NHL (4.5) and mesothelioma (4.2). KT recipients born in Southern Italy were at reduced risk of kidney cancer and solid tumors, though at a higher KS risk, than those born in Northern Italy. Use of mTOR inhibitors (mTORi) exerted, for all cancers combined, a 46% significantly reduced risk (95% CI: 0.4-0.7). Our study findings confirmed, in Italy, the increased risks for cancer following KT, and they also suggested a possible protective effect of mTORi in reducing the frequency of post transplant cancers.

Treatment of liver metastases in patients with digestive neuroendocrine tumors

BACKGROUND

Liver metastases are a strong prognostic indicator in patients with gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs). Therapeutic options for metastatic NETs are expanding and not mutually exclusive.

AIMS

This paper reviews the literature relating to multidisciplinary approach towards GEP-NET metastases, to highlight advances in knowledge regarding these tumors, and to understand the interdisciplinary management of individual patients.

METHODS

A PubMed search was performed for English-language publications from 1995 through 2012. Reference lists from studies selected were manually searched to identify further relevant reports. Manuscripts comparing different therapeutic options and advances for GEP-NET-related liver metastases were selected.

RESULTS

There is considerable controversy regarding the optimal management of GEP-NET metastases. Although radical surgery still remains the gold standard, a variety of other therapeutic options are available for metastatic GEP-NETs, including loco-regional chemotherapy/radiotherapy, radioembolization, systemic peptide receptor radionuclide therapy, biotherapy, and chemotherapy. In selected patients, liver transplantation should also be considered. Systemic somatostatin analogues and/or interferon show anti-proliferative effects, representing an appropriate first-line treatment for most patients. In advanced metastatic NETs, recent options include targeted therapies (i.e., everolimus and sunitinib).

CONCLUSIONS

It is evident that multidisciplinary care and multimodality treatments remain the cornerstone of management of NET patients. Since NETs often show a more indolent behavior compared to other malignancies, physicians should aim to preserve a satisfactory quality of life for the patient by personalizing the therapeutic approach according to the tumor's features and prognostic factors.

Phase I study of pasireotide (SOM 230) and everolimus (RAD001) in advanced neuroendocrine tumors

Octreotide and everolimus have demonstrated efficacy in neuroendocrine tumors. Pasireotide is a somatostatin analog with binding affinity to a broader range of somatostatin receptor subtypes than octreotide. We performed a phase I study to evaluate the safety and feasibility of combining pasireotide with everolimus in patients with advanced neuroendocrine tumors. Cohorts of patients with advanced neuroendocrine tumors were treated with escalating doses of pasireotide (600-1200  μg s.c. b.i.d., followed by pasireotide LAR 40-60  mg i.m. monthly) and everolimus (5-10  mg daily). Twenty-one patients were treated. Dose-limiting toxicities consisting of grade 3 rash and grade 3 diarrhea were observed. Twelve patients were safely treated at the maximum protocol-defined dose level of pasireotide LAR 60  mg i.m. monthly and everolimus 10  mg daily. Hyperglycemia was common; other observed toxicities were consistent with the known toxicities of either agent alone. Partial tumor response was observed in one patient; 17 (81%) patients experienced at least some tumor regression as their best response to therapy. In conclusion, pasireotide LAR 60  mg i.m. monthly in combination with everolimus 10  mg daily is feasible and associated with preliminary evidence of antitumor activity in patients with advanced neuroendocrine tumors. Further studies evaluating this combination are warranted.

The FGFR4-G388R single-nucleotide polymorphism alters pancreatic neuroendocrine tumor progression and response to mTOR inhibition therapy

Pancreatic neuroendocrine tumors (pNET), also known as islet cell tumors, exhibit a wide range of biologic behaviors ranging from long dormancy to rapid progression. Currently, there are few molecular biomarkers that can be used to predict recurrence/metastasis or response to therapy. This study examined the predictive and prognostic value of a single nucleotide polymorphism substituting an arginine (R) for glycine (G) in codon 388 of the FGFR4 transmembrane domain. We established the FGFR4 genotype of 71 patients with pNETs and correlated genotype with biologic behavior. We created an in vivo model of pNET with BON1 cells and transfected them with either FGFR4-G388 or FGFR4-R388 to determine the mechanism of action and to examine response to the mTOR inhibitor everolimus. We then validated the predictive results of experimental studies in a group of patients treated with everolimus. FGFR4-R388 is associated with more aggressive clinical behavior in patients with pNETs with a statistically significant higher risk of advanced tumor stage and liver metastasis. Using an orthotopic mouse xenograft model, we show that FGFR4-R388 promotes tumor progression by increasing intraperitoneal spread and metastatic growth within the liver. Unlike FGFR4-G388, FGFR4-R388 BON1 tumors exhibited diminished responsiveness to everolimus. Concordantly, there was a statistically significant reduction in response to everolimus in patients with FGFR4-R388. Our findings highlight the importance of the FGFR4 allele in pNET progression and identify a predictive marker of potential therapeutic importance in this disease.

A drug safety evaluation of everolimus in kidney transplantation

INTRODUCTION

Calcineurin inhibitors (CNI) have greatly reduced the rate of acute rejection and improved short-term graft survival after organ transplantation, however, long-term survival has hardly changed since their introduction. CNIs are believed to contribute to graft fibrosis, have side effects that adversely affect cardiovascular risk, and are associated with an increased rate of post-transplant malignancies. Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, is not associated with graft fibrosis, has a superior cardiovascular risk profile to CNI therapy and has shown potential for the prevention and treatment of diverse forms of cancer.

AREAS COVERED

This review summarizes key aspects of everolimus, including its mechanism of action, pharmacokinetics, pharmacodynamics, drug-drug interactions and pivotal clinical studies with a focus on safety and efficacy.

EXPERT OPINION

Everolimus is effective in improving graft function in selected kidney transplant patients. Most adverse events are present for a short time after the introduction of everolimus, and are manageable. Everolimus has the potential to become an important agent in de novo and maintenance immunotherapy in kidney transplant recipients.

Everolimus: a new treatment option for advanced pancreatic neuroendocrine tumors

OBJECTIVE

To present the current clinical evidence on everolimus for use in pancreatic neuroendocrine tumors (pNET).

DATA SOURCES

A literature search was performed using PubMed and MEDLINE (1946-March 2012). Search terms were everolimus, RAD001, mTOR inhibitor, and pancreatic neuroendocrine tumors. Abstracts from the American Society of Clinical Oncology 2000-2012 meetings and Food and Drug Administration (FDA) reviews were searched to obtain otherwise unpublished data. The national clinical trials registry was searched for current and future studies of everolimus in pNET.

STUDY SELECTION AND DATA EXTRACTION

Clinical studies available in the English language describing the pharmacology, pharmacokinetics, clinical activity, and safety of everolimus in pNET were included. All peer-reviewed, clinically relevant publications were reviewed for inclusion.

DATA SYNTHESIS

Everolimus is an oral mammalian target of rapamycin (mTOR) inhibitor approved by the FDA in May 2011 for the treatment of progressive, advanced pNET. Everolimus exerts its effect by inhibiting multiple downstream pathways of mTOR, which decreases cell proliferation, survival, and angiogenesis. Its pNET indication was based on the results of RADIANT-3, a Phase 3 trial demonstrating increased median progression-free survival (11 months) with everolimus 10 mg orally once daily compared to placebo (4.6 months). Everolimus was well tolerated in clinical trials. The most commonly reported adverse events included stomatitis, rash, diarrhea, fatigue, infections, nausea, and decreased appetite. Grade 3/4 events including anemia, thrombocytopenia, pneumonitis, and hyperglycemia occurred in approximately 5% of patients.

CONCLUSIONS

Based on review of the available literature, everolimus is a safe and effective treatment option for patients with low- to intermediate-grade, unresectable or metastatic pNET that have progressed on prior therapies. Until results of head-to-head, randomized controlled trials are conducted to compare everolimus to other treatment options, it cannot be said whether everolimus is more efficacious or tolerable than other treatment options.

Why RECIST works and why it should stay--counterpoint

Assessing that the efficacy of a cancer therapeutic is an integral part of its path to regulatory approval, we review the history that led to our current assessment method, Response Evaluation Criteria in Solid Tumors (RECIST). We describe the efforts of Moertel and Hanley to standardize response assessments in lymphoid malignancies and how this was adapted in the World Health Organization (WHO) criteria. Two decades later, RECIST was advanced to streamline WHO and improve its reproducibility. We describe the ways in which thresholds established by Moertel and Hanley to provide accuracy and reproducibility evolved to become measures of efficacy and why they have been valuable. While we recognize RECIST is far from perfect-in need of modification as a measure of efficacy for some agents and in some diseases-for the majority of solid tumors, it is very valuable. We argue that over time, the efficacy thresholds established by WHO and then RECIST have proved their worth, and we summarize 10 years of U.S. Food and Drug Administration (FDA) approvals in solid tumors to support our position that current RECIST thresholds should be retained.

Incidence and risk of pulmonary toxicity in patients treated with mTOR inhibitors for malignancy. A meta-analysis of published trials

BACKGROUND

mTOR inhibitors are currently used in the treatment of solid malignancies. Since their approval, several cases of pulmonary toxicity (PT) have been described. This analysis aims to report the incidence and the risk of PT in published randomized controlled trials.

MATERIAL AND METHODS

PubMed and Scopus were reviewed for phase II-III randomized controlled trials with temsirolimus and everolimus. The characteristic of each study and incidence of all- and high-grades PT were collected.

RESULTS

A total of 2233 patients were available for meta-analysis: 989 had breast cancer, 833 had neuroendocrine tumor and 411 had metastatic renal cell carcinoma. In patients taking mTOR inhibitors, the incidence of all- and high-grades PT was 10.4% and 2.4%, respectively. Compared to controls, the relative risk for all- and high-grades PT was 31- and 8.8-folds, respectively. No significant heterogeneity was observed between the studies. Not any relationship was found between the incidence of lung metastases, treatment exposure and the incidence of PT.

CONCLUSIONS

The high grade PT is a rare event and 10% of patients may experience mild grade toxicity with a worsening of quality of life and interruption of therapy in some cases. We recommend monitoring of PT in patients treated with mTOR inhibitors.

Therapy of metastatic pancreatic neuroendocrine tumors (pNETs): recent insights and advances

Neuroendocrine tumors (NETs) [carcinoids, pancreatic neuroendocrine tumors (pNETs)] are becoming an increasing clinical problem because not only are they increasing in frequency, but they can frequently present with advanced disease that requires diagnostic and treatment approaches different from those used in the neoplasms that most physicians are used to seeing and treating. In the past few years there have been numerous advances in all aspects of NETs including: an understanding of their unique pathogenesis; specific classification systems developed which have prognostic value; novel methods of tumor localization developed; and novel treatment approaches described. In patients with advanced metastatic disease these include the use of newer chemotherapeutic approaches, an increased understanding of the role of surgery and cytoreductive methods, the development of methods for targeted delivery of cytotoxic agents, and the development of targeted medical therapies (everolimus, sunitinib) based on an increased understanding of the disease biology. Although pNETs and gastrointestinal NETs share many features, recent studies show they differ in pathogenesis and in many aspects of diagnosis and treatment, including their responsiveness to different therapies. Because of limited space, this review will be limited to the advances made in the management and treatment of patients with advanced metastatic pNETs over the past 5 years.

Carcinoid heart disease

Carcinoid tumors are rare, indolent neuroendocrine tumors that are often associated with a syndrome characterized by episodic flushing, secretory diarrhea, bronchospasm, and hypotension-the carcinoid syndrome. Cardiac involvement occurs in one-half to two-thirds of patients with carcinoid syndrome and is associated with a worse clinical outcome. Carcinoid heart disease is characterized by endocardial plaque-like deposits found predominantly on right-sided heart valves, leading to the combination of valvular stenosis and regurgitation. Left-sided cardiac involvement can also occur in <10% of patients. Somatostatin analogs form the therapeutic cornerstone in the medical management of these patients. Cytotoxic chemotherapy has had only limited success in the treatment of metastatic carcinoid tumors. Hepatic resection or palliative cytoreduction may be of benefit in patients with limited hepatic disease. Hepatic artery embolization is usually applied if a patient is not eligible for surgical debulking. The development and progression of carcinoid heart disease are associated with an unfavorable outcome. In those patients having severe cardiac involvement and well-controlled systemic disease, valve replacement surgery has been found to be an effective treatment that can both relieve intractable symptoms and contribute to improved clinical outcomes.

The role of mTOR signaling pathway in spinal cord injury

The mammalian target of rapamycin (mTOR) signaling pathway plays an important role in multiple cellular functions, such as cell metabolism, proliferation and survival. Many previous studies have shown that mTOR regulates both neuroprotective and neuroregenerative functions in trauma and various diseases in the central nervous system (CNS). Recently, we reported that inhibition of mTOR using rapamycin reduces neural tissue damage and locomotor impairment after spinal cord injury (SCI) in mice. Our results demonstrated that the administration of rapamycin at four hours after injury significantly increases the activity of autophagy and reduces neuronal loss and cell death in the injured spinal cord. Furthermore, rapamycin-treated mice show significantly better locomotor function in the hindlimbs following SCI than vehicle-treated mice. These findings indicate that the inhibition of mTOR signaling using rapamycin during the acute phase of SCI produces neuroprotective effects and reduces secondary damage at lesion sites. However, the role of mTOR signaling in injured spinal cords has not yet been fully elucidated. Various functions are regulated by mTOR signaling in the CNS, and multiple pathophysiological processes occur following SCI. Here, we discuss several unresolved issues and review the evidence from related articles regarding the role and mechanisms of the mTOR signaling pathway in neuroprotection and neuroregeneration after SCI.

Profiling mTOR pathway in neuroendocrine tumors

The serine/threonine kinase mammalian target of rapamycin (mTOR) plays a central role in regulating critical cellular processes such as growth, proliferation, and protein synthesis. The study of cancer predisposing syndromes within which neuroendocrine tumors (NETs) may arise has furnished clues on the involvement of mTOR pathway in sporadic diseases so far. Recent comprehensive analyses have definitely shown activation of mTOR pathway in both experimental and human sporadic NETs. Upstream regulators of mTOR (PTEN and TSC2) have been found mutated in sporadic pNETs. Activation of mTOR pathways in NETs is already demonstrated by expression profiles analysis that revealed downregulation of TSC2 gene and alterations of TSC2 and PTEN protein expression in the vast majority of well-differentiated tumors. Moreover, a global microRNA expression analysis revealed the overexpression, in highly aggressive tumors, of a microRNA (miR-21) that targets PTEN reducing its expression and therefore leading to mTOR activation as well. Overall, these clues have furnished the rationale for the use of mTOR inhibitors the treatment of pNETs. With the recent approval of Everolimus (mTOR-targeted drug) for the treatment of advanced pNETs, this paradigm has been effectively translated into the clinical setting. In this review, we discuss mTOR pathway involvement in NETs, the clinical evidence supporting the use of mTOR inhibitors in cancer treatment, and the current clinical issues that remain to be elucidated to improve patient management.

Profiling mTOR pathway in neuroendocrine tumors

The serine/threonine kinase mammalian target of rapamycin (mTOR) plays a central role in regulating critical cellular processes such as growth, proliferation, and protein synthesis. The study of cancer predisposing syndromes within which neuroendocrine tumors (NETs) may arise has furnished clues on the involvement of mTOR pathway in sporadic diseases so far. Recent comprehensive analyses have definitely shown activation of mTOR pathway in both experimental and human sporadic NETs. Upstream regulators of mTOR (PTEN and TSC2) have been found mutated in sporadic pNETs. Activation of mTOR pathways in NETs is already demonstrated by expression profiles analysis that revealed downregulation of TSC2 gene and alterations of TSC2 and PTEN protein expression in the vast majority of well-differentiated tumors. Moreover, a global microRNA expression analysis revealed the overexpression, in highly aggressive tumors, of a microRNA (miR-21) that targets PTEN reducing its expression and therefore leading to mTOR activation as well. Overall, these clues have furnished the rationale for the use of mTOR inhibitors the treatment of pNETs. With the recent approval of Everolimus (mTOR-targeted drug) for the treatment of advanced pNETs, this paradigm has been effectively translated into the clinical setting. In this review, we discuss mTOR pathway involvement in NETs, the clinical evidence supporting the use of mTOR inhibitors in cancer treatment, and the current clinical issues that remain to be elucidated to improve patient management.

Inhibition of mTOR in carcinoid tumors

Neuroendocrine neoplasms (NEN) are a heterogeneous group of tumors, whose incidence and prevalence are increasing. The clinical behavior of NEN is variable, ranging from well-differentiated slow growing tumors to highly aggressive poorly differentiated neuroendocrine carcinomas. The term carcinoid is commonly used for the more benign variants of these neoplasms. Most frequently, carcinoids have their origin in the small intestine, followed by in the lung and other sites. Some of these tumors are associated with the carcinoid syndrome. The use of somatostatin analogs has revolutionized the clinical management of patients with carcinoids. However, although symptomatic relief and stabilization of tumor growth for various periods of time are observed in many patients treated with somatostatin analogs, tumor regression is rare. Currently, there is no other powerful antiproliferative agent available for carcinoids. Mammalian target of rapamycin (mTOR), a main protein kinase in the phosphoinositide 3-kinase/Akt/p70S6K signaling pathway, is an important intracellular mediator involved in multiple cellular functions including proliferation, differentiation, apoptosis, tumorigenesis, and angiogenesis. Alterations of the normal activity of mTOR and of mTOR-related kinases in this pathway have been found in a diversity of human tumors, including NEN; therefore, mTOR pathway represents an attractive target for new anticancer therapies. While mTOR inhibitors, such as everolimus, are established therapy in pancreatic NEN, results from recent clinical trials indicate that mTOR inhibitors may be also of value in the management of carcinoids. However, further clinical trials will have to confirm efficacy and elucidate, in which subtypes and in which setting, these drugs might be most usefully applied.

Systemic therapy of neuroendocrine tumors of the lung

SUMMARY Pulmonary neuroendocrine tumors (pNETs) are normally included in trials comprising neuroendocrine tumors (NETs) of different organs of origin. Typical and atypical carcinoids are regarded as low-grade NETs and show low proliferation rates and minor responses with classic chemotherapy regimens. Somatostatin analogs were traditionally applied in patients with carcinoid syndrome and recently also demonstrated tumor response. Recently, novel agents such as sunitinib and everolimus showed improved survival in randomized studies. These trials contained only low numbers of pNETs. Another promising field of targeted therapy in low-grade NETs includes peptide receptor radionuclide therapy. High-grade pNETs include large-cell neuroendocrine carcinoma and small-cell lung cancer. We will discuss large-cell neuroendocrine carcinoma and will address small-cell lung cancer at the end of this review.

Efficacy of everolimus, a novel mTOR inhibitor, against basal-like triple-negative breast cancer cells

Patients with triple-negative breast cancers (TNBCs) typically have a poor prognosis because such cancers have no effective therapeutic targets, such as estrogen receptors for endocrine therapy or human epidermal growth factor receptor 2 (HER2) receptors for anti-HER2 therapy. As the phosphatidylinositol 3' kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) cascade is activated in TNBCs, mTOR is a potential molecular target for anticancer therapy. In this study, we investigated the antitumor activities of everolimus, an oral mTOR inhibitor, in nine TNBC cell lines. Everolimus effectively inhibited cell growth at concentrations under 100 nM (IC(50)) in five cell lines and even in the 1-nM range in three of the five cell lines. To identify specific characteristics that could be used as predictive markers of efficacy, we evaluated the expressions of proteins in the mTOR cascade, basal markers, and cancer stem cell markers using western blotting, fluorescent in situ hybridization (FISH), or immunohistochemistry. All five of the sensitive cell lines were categorized as a basal-like subtype positive for either epidermal growth factor receptor (EGFR) or CK5/6, although resistant cell lines were not of this subtype and tended to exhibit the characteristics of cancer stem cells, with decreased E-cadherin and the increased expression of Snail or Twist. In vivo assays demonstrated antitumor activity in a mouse xenograft model of basal-like breast cancer, rather than non-basal breast cancer. These results suggest that everolimus has favorable activity against basal-like subtypes of TNBCs. Epidermal growth factor receptor and CK5/6 are positive predictive markers of the TNBC response to everolimus, while cancer stem cell markers are negative predictive markers.

Treatment of pulmonary neuroendocrine tumours: state of the art and future developments

The current classification of pulmonary neuroendocrine tumours includes four subtypes: low-grade typical carcinoid tumour (TC), intermediate-grade atypical carcinoid tumour (AC), and two high-grade malignancies: large cell neuroendocrine carcinoma and small cell lung cancer (SCLC). Unfortunately, with the exclusion of SCLC, no large phase II and III trials for pulmonary neuroendocrine tumours have been published. Thus, several treatment approaches are available for their treatment but none of them has been validated in appropriately designed and adequately sized clinical trials. The main problem of the published studies is that they include neuroendocrine tumours from various sites of origin with different clinical behaviour. It is important that future studies consider these tumours separately. In this regard, increased awareness and referral of these patients to tertiary centres, in which a multidisciplinary management is available, may be of value. The aim of this review is to evaluate the state of the art and discuss future developments in the management of pulmonary neuroendocrine tumours excluding SCLC which we consider should be addressed in a different issue.

Temozolomide and unusual indications: review of literature

Temozolomide (TMZ) was first known to be useful as a radiosensitiser in both primary brain tumours like glioblastoma multiforme and oligodendroglioma. Later, TMZ proved its efficacy in the treatment of melanoma. Multiple publications have demonstrated the benefit of TMZ in terms of efficacy and tolerance (used as mono-therapy or as adjuvant chemotherapy) compared to the "gold standard" treatment of this kind of tumours. Furthermore, several recent clinical trials have shown the particular importance of TMZ in other types of cancer. This publication deals with the use of TMZ in cancers which are not formal indications for TMZ (excluding glioblastoma multiforme, oligodendroglioma and melanoma). It also includes a necessary review of recent literature about the role of TMZ in the treatment of brain metastases, lymphomas, refractory leukaemia, neuroendocrine tumours, pituitary tumours, Ewing's sarcoma, primitive neuroectodermal tumours, lung cancer and other tumours.

Current status and perspectives of targeted therapy in well-differentiated neuroendocrine tumors

Although neuroendocrine tumors (NET) are a relatively rare malignancy, the reported incidence is increasing, and some of the current treatment options are limited in their efficacy. Standard first-line therapy for metastatic small bowel NET includes somatostatin analogs. Although these agents can provide symptom relief and can delay disease progression in many patients, ultimately, new treatments are required for patients with progressive disease. In recent years, there has been considerable interest in developing agents specifically targeted against some of the pathways known to be involved in cancer cell growth, survival and invasion. In 2011, the mammalian target of rapamycin (mTOR) inhibitor everolimus and the tyrosine kinase inhibitor sunitinib were approved for the treatment of pancreatic NET. Clinical trials evaluating novel targeted agents are ongoing, both as single agents and in combination regimens. We review the current clinical status of these potential new treatments and highlight those with particular promise for the management of well-differentiated NET.

Phase 2 study of everolimus monotherapy in patients with nonfunctioning neuroendocrine tumors or pheochromocytomas/paragangliomas

BACKGROUND

The current study was conducted to evaluate the efficacy and safety of everolimus in the treatment of patients with nonfunctioning neuroendocrine tumors (NETs) or pheochromocytomas/paragangliomas.

METHODS

Patients with histologically confirmed nonfunctioning NETs or pheochromocytomas/paragangliomas and with documented disease progression before study enrollment were eligible for the current study. Everolimus was administered daily at a dose of 10 mg for 4 weeks. Response was assessed by Response Evaluation Criteria In Solid Tumors (RECIST; version 1.0) every 8 weeks. The primary endpoint was the 4-month progression-free survival rate (PFSR). The hypothesis of the current study was that the 4-month PFSR would increase from 50% to 65%. Safety was evaluated using the National Cancer Institute's Common Terminology Criteria for Adverse Events (version 3.0).

RESULTS

A total of 34 patients were enrolled. Of these, 27 patients had nonfunctioning NETs, 5 had pheochromocytomas, and 2 had paragangliomas. The 4-month PFSR was 78%. Partial response (PR) was observed in 3 patients. Twenty-eight patients had stable disease (SD) and 2 patients developed progressive disease (PD). The response rate (RR) and overall disease control rate (DCR) were 9.0% (95% confidence interval [95% CI], 0%-18.6%) and 93.9% (95% CI, 85.8%-100%), respectively. The PFS was 15.3 months (95% CI, 4.6 months-26.0 months). Of the patients with nonfunctioning NETs, 3 achieved a PR and 23 had SD (RR, 11.1%; DCR, 100%); the PFS was 17.1 months (95% CI, 11.1 months-23.0 months) and the 4-month PFSR was 90.0%. Twenty-one patients (80.8%) demonstrated tumor shrinkage. In 7 patients with pheochromocytomas/paragangliomas, 5 achieved SD, and 2 developed PD. The PFS was 3.8 months (95% CI, 0.5 months-7.0 months) and the 4-month PFSR was 42.9%. Four patients demonstrated tumor shrinkage. The major grade 3/4 adverse events were thrombocytopenia (14.7%), hyperglycemia (5.9%), stomatitis (5.9%), and anemia (5.9%).

CONCLUSIONS

Everolimus was associated with high therapeutic efficacy and tolerability in patients with nonfunctioning NETs, and demonstrated modest efficacy in patients with pheochromocytomas/paragangliomas.

Perifosine-mediated Akt inhibition in neuroendocrine tumor cells: role of specific Akt isoforms

The majority of neuroendocrine tumors (NETs) of the gastroenteropancreatic system show aberrant Akt activity. Several inhibitors of the phosphoinositide 3-kinase (PI(3)K)-Akt-mTOR signaling pathway are currently being evaluated in clinical phase II and III studies for the treatment of NETs with promising results. However, the molecular mechanisms and particularly the role of different Akt isoforms in NET signaling are not fully understood. In this study, we examine the effect of Akt inhibition on NET cells of heterogeneous origin. We show that the Akt inhibitor perifosine effectively inhibits Akt phosphorylation and cell viability in human pancreatic (BON1), bronchus (NCI-H727), and midgut (GOT1) NET cells. Perifosine treatment suppressed the phosphorylation of Akt downstream targets such as GSK3α/β, MDM2, and p70S6K and induced apoptosis. To further investigate the role of individual Akt isoforms for NET cell function, we specifically blocked Akt1, Akt2, and Akt3 via siRNA transfection. In contrast to Akt2 knockdown, knockdown of Akt isoforms 1 and 3 decreased phosphorylation levels of GSK3α/β, MDM2, and p70S6K and suppressed NET cell viability and colony-forming capacity. The inhibitory effect of simultaneous downregulation of Akt1 and Akt3 on tumor cell viability was significantly stronger than that caused by downregulation of all Akt isoforms, suggesting a particular role for Akt1 and Akt3 in NET signaling. Akt3 siRNA-induced apoptosis while all three isoform-specific siRNAs impaired BON1 cell invasion. Together, our data demonstrate potent antitumor effects of the pan-Akt inhibitor perifosine on NET cells in vitro and suggest that selective targeting of Akt1 and/or Akt3 might improve the therapeutic potential of Akt inhibition in NET disease.

Hitting the target: where do molecularly targeted therapies fit in the treatment scheduling of neuroendocrine tumours?

Neuroendocrine tumours (NETs) are a rare and heterogeneous group of tumours whose incidence is increasing and their prevalence is now greater than that of any other upper gastrointestinal tumour. Diagnosis can be challenging, and up to 25% of patients present with metastatic disease. Following the recent FDA approval of two new molecularly targeted therapies for the treatment of advanced pancreatic NETs (pNETs), the first in 25 years, we review all systemic therapies and suggest where these newer targeted therapies fit in the treatment schedule for these challenging tumours. Clinical trial data relating to the routine use of sunitinib and everolimus in low-intermediate-grade pNETs are summarised alongside newer molecularly targeted agents undergoing clinical assessment in NETs. We particularly focus on the challenge of optimal scheduling of molecularly targeted treatments around existing systemic and localised treatment such as chemotherapy or radiotargeted therapy. We also discuss application of current evidence to subgroups of patients who have not so far been directly addressed such as those with poorer performance status or patients receiving radical surgery who may benefit from adjuvant treatment.

Antitumor effects of somatostatin analogs in neuroendocrine tumors

BACKGROUND

For decades, somatostatin analogs (including octreotide and lanreotide) have been indicated for relief of the symptoms of flushing, diarrhea, and wheezing associated with secretory neuroendocrine tumors (NETs). Recently, it has been suggested that somatostatin analogs may provide direct and indirect antitumor effects in secretory and nonsecretory NETs in addition to symptom control in secretory NETs.

METHODS

A systematic review of MEDLINE was conducted to identify studies that investigated the antitumor effects of octreotide or lanreotide for patients with NETs. Additional studies not published in the peer-reviewed literature were identified by searching online abstracts. Results. In all, 17 octreotide trials and 11 lanreotide trials that included antitumor effects were identified. Partial response rates were between 0% and 31%, and stable disease rates were between 15% and 89%. Octreotide was the only somatostatin analog for which results of a phase III, randomized, placebo-controlled clinical trial that investigated antitumor effects were published. After 6 months of treatment in this randomized phase III trial, stable disease was observed in 67% of patients (hazard ratio for time to disease progression: 0.34; 95% confidence interval: 0.20-0.59; p = .000072).

CONCLUSIONS

In addition to symptom control for NETs, the data support an antitumor effect of somatostatin analogs and suggest that they may slow tumor growth. Long-acting repeatable octreotide has been shown to have an antitumor effect in a randomized phase III trial in midgut NETs, whereas results are pending in a corresponding controlled trial with lanreotide for patients with intestinal and pancreatic primary NETs.