A phase 2 study with a daily regimen of the oral mTOR inhibitor RAD001 (everolimus) in patients with metastatic clear cell renal cell cancer

[PI3K-AKT-mTOR pathway and cancer]

PI3K/AKT/mTOR pathway is an intracellular signalling pathway composed of different kinases. Many protein mutations are described in that pathway, and are responsible of dysregulation of cell growth, proliferation, survival and angiogenesis. Rapamycin is an antibiotic inhibiting mTOR. Different analogs of rapamycin are developed or being developed in antitumoral therapy, in which temsirolimus, everolimus and deforolimus, demonstrated antitumoral activity in renal cancer and mantle cell lymphoma, and many clinical trials are in progress in other tumors. In the future, predictive factors of response need to be identified; patient selection and associations with chemotherapy or with other targeted therapies should be explored.

Synergistic anti-tumor effects of RAD001 with MEK inhibitors in neuroendocrine tumors: a potential mechanism of therapeutic limitation of mTOR inhibitor

Mammalian target of rapamycin (mTOR) inhibitors have been clinically used as anticancer agents in several types of human malignancies including neuroendocrine tumor (NET) but the development of clinical resistances or their therapeutic limitations have been also reported. This clinical resistance has been proposed to be partly due to a compensatory activation of an mTOR upstream factor Akt and MEK/ERK pathway in NET cells but its details have not necessarily been reported. Therefore, in this study, we examined the effects of mTOR inhibitors on these activations and of the concomitant treatment of mTOR and MEK inhibitors in two NET cell lines, NCI-H727 and COLO320. We evaluated the effects of RAD001, mTOR inhibitor, and U0126, MEK inhibitor, on cell proliferation and migration of these cells. In addition, an alteration of the factors involved in Akt/mTOR and MEK/ERK pathways was also examined under administration of these agents. RAD001 and U0126 treatment significantly inhibited cell proliferation and their combined treatment synergistically decreased it in both cell lines. Additionally, these treatments above decreased the expression of cell cycle-related factors, suggestive of an involvement of cell cycle arrest in therapeutic effects. The combined treatment also inhibited the cell migration in NCI-H727 via the decrement of MMP2 and 9 in an additive manner. We demonstrated the potential synergistic/combined effects of inhibitors of mTOR and MEK on cell proliferation and migration. These results suggest the potential therapeutic efficacy of the combined therapy of mTOR and MEK inhibitors or a dual inhibitor for the treatment of NET patients.

Targeted therapies for renal cell carcinoma: review of adverse event management strategies

With the advent of targeted agents for the treatment of renal cell carcinoma (RCC), overall survival has improved, and patients are being treated continuously for increasingly long periods of time. This has raised challenges in the management of adverse events (AEs) associated with the six targeted agents approved in RCC-sorafenib, sunitinib, pazopanib, bevacizumab (in combination with interferon alpha), temsirolimus, and everolimus. Suggestions for monitoring and managing AEs have been published, but there are few consensus recommendations. In addition, there is a risk that patients will be subjected to multiple unnecessary investigations. In this review, we aimed to identify the level of supporting evidence for suggested AE management strategies to provide practical guidance on essential monitoring and management that should be undertaken when using targeted agents. Five databases were systematically searched for relevant English language articles (including American Society of Clinical Oncology abstracts) published between January 2007 and March 2011; European Society of Medical Oncology congress abstracts were hand searched. Strategies for AE management were summarized and categorized according to the level of recommendation. A total of 107 articles were identified that describe a large number of different investigations for monitoring AEs and interventions for AE management. We identify and summarize clear recommendations for the management of dermatologic, gastrointestinal, thyroid, cardiovascular, and other AEs, based predominantly on expert opinion. However, because the evidence for the suggested management strategies is largely anecdotal, there is a need for further systematic investigation of management strategies for AEs related to targeted therapies for RCC.

PI3Ks-drug targets in inflammation and cancer

Phosphoinositide 3-kinases (PI3Ks) control cell growth, proliferation, cell survival, metabolic activity, vesicular trafficking, degranulation, and migration. Through these processes, PI3Ks modulate vital physiology. When over-activated in disease, PI3K promotes tumor growth, angiogenesis, metastasis or excessive immune cell activation in inflammation, allergy and autoimmunity. This chapter will introduce molecular activation and signaling of PI3Ks, and connections to target of rapamycin (TOR) and PI3K-related protein kinases (PIKKs). The focus will be on class I PI3Ks, and extend into current developments to exploit mechanistic knowledge for therapy.

mTOR inhibitors in advanced renal cell carcinoma

Better understanding of the molecular biology of renal cell carcinoma (RCC) has led to the development of several targeted anti-cancer agents, several of which have since received approval for treatment of advanced disease. Two of these, the intravenous agent temsirolimus and the oral everolimus, exhibit antitumor effects through inhibition of the mammalian target of rapamycin (mTOR) pathway. This article reviews their mechanisms of action in the context of the current understanding of RCC pathophysiology, the clinical data leading to their approval, class-specific toxicities, potential molecular mechanisms behind treatment resistance and novel treatment approaches for RCC that incorporate mTOR blockade.

Emerging roles for mammalian target of rapamycin inhibitors in the treatment of solid tumors and hematological malignancies

PURPOSE OF REVIEW

The mammalian target of rapamycin (mTOR) is a key regulator of cell growth and survival in mammalian cells. mTOR pathways are frequently dysregulated in various malignancies, providing targets for new anticancer drugs and therapeutic strategies. Here, we summarize the clinical experience of trials using the first generation of mTOR inhibitors, the rapalogs, and highlight the development of the next generation of catalytic inhibitors of the pathway.

RECENT FINDINGS

mTOR inhibitors have shown major clinical activity in the treatment of renal cell carcinoma and two rapalogs have been approved for treatment of this malignancy. Recently, clinically significant trials with these agents were conducted in mantle cell lymphoma, pancreatic neuroendocrine tumors and astrocytomas. There are also promising results emerging in sarcomas, breast cancer and lung carcinoma. Multiple agents targeting mTOR, belonging to the new class of catalytic inhibitors with activity against both mTORC1 and mTORC2, are currently in various stages of preclinical and clinical development.

SUMMARY

The rapalogs are the first mTOR inhibitors to show promising, yet modest, antitumor effects. To fully exploit the potential of targeting this pathway, it will be important to better understand the mechanisms of action and precise targets of the various inhibitors. Moreover, definition of biomarkers of susceptibility and identification of predictors and/or correlates to drug resistance will substantially advance this area.

Potential Therapeutic Roles for Inhibition of the PI3K/Akt/mTOR Pathway in the Pathophysiology of Diabetic Retinopathy

Novel therapeutics such as inhibitors of PI3K/Akt/mTOR pathway presents a unique opportunity for the management of diabetic retinopathy (DR). Second generation mTOR inhibitors have the prospect to be efficacious in managing various stages of disease progression in DR. During early stages, the mTOR inhibitors suppress HIF-1α, VEGF, leakage, and breakdown of the blood-retinal barrier. These mTOR inhibitors impart a pronounced inhibitory effect on inflammation, an early component with diverse ramifications influencing the progression of DR. These inhibitors suppress IKK and NF-κB along with downstream inflammatory cytokines, chemokines, and adhesion molecules. In proliferative DR, mTOR inhibitors suppress several growth factors that play pivotal roles in the induction of pathological angiogenesis. Lead mTOR inhibitors in clinical trials for ocular indications present an attractive treatment option for chronic use in DR with favorable safety profile and sustained ocular pharmacokinetics following single dose. Thereby, reducing dosing frequency and risk associated with chronic drug administration.

Pharmacokinetic drug interaction between AEE788 and RAD001 causing thrombocytopenia in patients with glioblastoma

PURPOSE

Treating glioblastoma through the simultaneous inhibition of multiple transduction pathways may prove more effective than single-pathway inhibition. We evaluated the safety, biologic activity, and pharmacokinetic profile of oral AEE788, a selective inhibitor of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF), plus oral RAD001, a mammalian target of rapamycin inhibitor, in glioblastoma patients.

METHODS

This phase IB/II, open-label, multicenter, 2-arm, dose-escalation study enrolled adult glioblastoma patients at first or second recurrence/relapse. Primary objective was to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of AEE788 combined with RAD001. Secondary objectives included determining the safety/tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity of the combination.

RESULTS

Sixteen patients were enrolled (AEE788 200 mg/day + RAD001 5 mg/day, 2 patients; AEE788 150 mg/day + RAD001 5 mg every other day [qod], 14); all patients discontinued the study most commonly because of disease progression. Four patients experienced DLT (AEE788 200 mg/day + RAD001 5 mg/day, 1 patient; AEE788 150 mg/day + RAD001 5 mg qod, 3). Both patients receiving AEE788 (200 mg/day) plus RAD001 (5 mg/day) experienced clinically significant thrombocytopenia requiring a dose reduction/interruption. AEE788 appeared to inhibit the metabolism of RAD001. The study was terminated prematurely before an MTD was determined because of safety findings in other studies evaluating AEE788 monotherapy.

CONCLUSIONS

The coadministration of AEE788 and RAD001 in glioblastoma patients caused a clinically significant thrombocytopenia and a higher-than-expected RAD001 area under the curve concentration when dosed at 200 and 5 mg/day, respectively. After a dose reduction to AEE788 (150 mg/day) and RAD001 (5 mg qod), the combination appeared to be better tolerated.

Clinical presentation and management of mTOR inhibitor-associated stomatitis

Anti-cancer agents that inhibit the mTOR pathway are associated with a number of unique toxicities, with one of the most significant and potentially dose-limiting being stomatitis. The objective of this study was to report the clinical features and management outcomes of a series of cancer patients who developed painful mTOR inhibitor-associated stomatitis (mIAS). Seventeen cancer patients developed mIAS while being treated with everolimus- or ridaforolimus-containing protocols at the Dana-Farber Cancer Institute and were referred to the oral medicine clinic for evaluation and management. Clinical characteristics, toxicity management, and outcomes were summarized. In addition, the frequency and rationale for dose reductions and therapy discontinuation were assessed. The median duration of mTOR inhibitor therapy was 80 days (range 9-187 days). The median time to development of mouth ulcers was 10 days (range 4-25 days). Five patients required protocol-directed dose reductions due to grades 2 and 3 stomatitis and one patient discontinued cancer treatment due to mouth ulcers. Clinical improvement and pain relief was reported in 86.6% of patients following topical, intralesional, or systemic corticosteroid therapy, with side effects limited to secondary candidiasis (n=2). Mouth ulcers are a common and potentially dose limiting toxicity associated with the use of mTOR inhibitors in cancer treatment. This case series demonstrates that local and systemic corticosteroid therapy is an effective approach to managing patients with symptomatic mIAS. Prospective studies are necessary to evaluate the effectiveness of treatment and prevention strategies with the ultimate goal of improving overall cancer treatment outcomes.

Antroquinonol, a natural ubiquinone derivative, induces a cross talk between apoptosis, autophagy and senescence in human pancreatic carcinoma cells

Pancreatic cancer is a malignant neoplasm of the pancreas. A mutation and constitutive activation of K-ras occurs in more than 90% of pancreatic adenocarcinomas. A successful approach for the treatment of pancreatic cancers is urgent. Antroquinonol, a ubiquinone derivative isolated from a camphor tree mushroom, Antrodia camphorata, induced a concentration-dependent inhibition of cell proliferation in pancreatic cancer PANC-1 and AsPC-1 cells. Flow cytometric analysis of DNA content by propidium iodide staining showed that antroquinonol induced G1 arrest of the cell cycle and a subsequent apoptosis. Antroquinonol inhibited Akt phosphorylation at Ser(473), the phosphorylation site critical for Akt kinase activity, and blocked the mammalian target of rapamycin (mTOR) phosphorylation at Ser(2448), a site dependent on mTOR activity. Several signals responsible for mTOR/p70S6K/4E-BP1 signaling cascades have also been examined to validate the pathway. Moreover, antroquinonol induced the down-regulation of several cell cycle regulators and mitochondrial antiapoptotic proteins. In contrast, the expressions of K-ras and its phosphorylation were significantly increased. The coimmunoprecipitation assay showed that the association of K-ras and Bcl-xL was dramatically augmented, which was indicative of apoptotic cell death. Antroquinonol also induced the cross talk between apoptosis, autophagic cell death and accelerated senescence, which was, at least partly, explained by the up-regulation of p21(Waf1/Cip1) and K-ras. In summary, the data suggest that antroquinonol induces anticancer activity in human pancreatic cancers through an inhibitory effect on PI3-kinase/Akt/mTOR pathways that in turn down-regulates cell cycle regulators. The translational inhibition causes G1 arrest of the cell cycle and an ultimate mitochondria-dependent apoptosis. Moreover, autophagic cell death and accelerated senescence also explain antroquinonol-mediated anticancer effect.

Phase I and pharmacokinetic study of capecitabine and the oral mTOR inhibitor everolimus in patients with advanced solid malignancies

Background Everolimus is an oral mTOR-inhibitor. Preclinical data show synergistic effects of mTOR inhibition in combination with 5-fluorouracil-based anticancer therapy. The combination of everolimus with capecitabine seems therefore an attractive new, orally available, treatment regimen. Patients and methods Safety, preliminary efficacy and pharmacokinetics of everolimus in combination with capecitabine were investigated in patients with advanced solid malignancies. Patients were treated with fixed dose everolimus 10 mg/day continuously, plus capecitabine bid for 14 days in three-weekly cycles. Dose escalation of capecitabine proceeded according to the standard 3 × 3 phase I design in four predefined dose levels (500–1,000 mg/m² bid). Results In total, 18 patients were enrolled. Median (range) treatment duration with everolimus was 70 days (21–414). Capecitabine 1,000 mg/m² bid combined with 10 mg/day everolimus was declared the maximum tolerated dose, at which level one patient developed dose-limiting toxicity (stomatitis grade 3). Drug-related adverse events were mostly grade ≤2 and included mainly fatigue (56%), stomatitis (50%), and hand-foot syndrome (33%). Partial response was documented in three patients, and four had stable disease. There was no pharmacokinetic interaction between everolimus and capecitabine. Conclusion Everolimus 10 mg/day continuously combined with capecitabine 1,000 mg/m² bid for 14 days every 3 weeks is a patient-convenient, safe and tolerable oral treatment regimen. This is the first study to demonstrate feasibility of this combination at doses with proven single agent efficacy in a number of tumors. Prolonged clinical benefit was observed in an encouraging 39% of patients with advanced solid malignancies.

pS6 Expression in normal renal parenchyma, primary renal cell carcinomas and their metastases

In cancer therapy novel concepts focus on phosphoinositide-3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) inhibitors. In this context, phosphorylated S6 protein of the 40S ribosomal subunit (pS6) overexpression was previously shown to be associated with sensitivity to inhibitors of mTOR. The present study therefore evaluated pS6 expression in normal renal parenchyma (NRP), primary renal cell carcinomas (PRCC) and their metastases. pS6 and pmTOR expression was immunohistochemically analyzed in a tissue microarray (TMA) from localized primary renal cell carcinoma (lPRCC) (n = 35), metastasized primary renal cell carcinoma (mPRCC) (n = 45), their metastases (n = 45), and NRP (n = 45). pS6 expression was stronger in mPRCCs and metastases than in NRP and lPRCCs (p < 0.05). In mPRCCs high-grade and high-stage tumors showed higher pS6 levels. pS6 overexpression was more frequently found in metastases (40/45; 88.9%) than in mPRCC (24/45; 53.3%) (p < 0.05). Overexpression of pS6 in metastases without concomitant overexpression in their primary tumors was found in 16/45 (35.56%) cases. Patients with pS6 overexpression in mPRCCs but also in metastases showed a tendency to shorter overall survival. pS6 score and pmTOR score correlated positively in NRP and in tumorous tissue (mPRCC and metastases). In conclusion, the present study showed stronger pS6 expression and more frequent overexpression in metastases than in corresponding PRCCs. In approximately one-third of the cases pS6 overexpression was found exclusively in metastases, which is interesting with regard to the association between high pS6 expression and sensitivity to mTOR inhibitor therapy.

Clinical experience and critical evaluation of the role of everolimus in advanced renal cell carcinoma

The efficacy of sequential everolimus, an orally administered inhibitor of mammalian target of rapamycin (mTOR), was proven in a placebo-controlled phase III study, where median progression-free survival was 4.9 vs 1.9 months for placebo (hazard ratio: 0.33, P < 0.001). Placebo crossovers (80%) contaminated overall survival data. Adverse event discontinuation rate was of only 10% and health-adjusted quality-of-life was sustained. These data represent the first placebo-controlled evidence of efficacy for a sequentially used targeted agent. Everolimus resulted in the strongest hazard ratio ever recorded for progression-free survival, despite it being tested in a population with the most aggressive natural history ever recorded in all available phase III metastatic renal cell carcinoma trials. Everolimus use after exclusively one prior antivascular endothelial growth factor failure resulted in an even longer progression-free survival time (5.4 months) than in the entire population (4.9 months). These benefits should also be considered in the light of sustained and unimpaired health-related quality of life. Use in first line other than second or subsequent lines remains to be validated.

Research and innovation in the development of everolimus for oncology

INTRODUCTION

The critical role of increased activity of mammalian target of rapamycin (mTOR) in the pathophysiology of multiple diseases is well established. Inhibition of the mTOR pathway may block disease progression and improve patient outcomes. Everolimus, an mTOR inhibitor, began in clinical development as part of a regimen (Certican, Zortress) for prevention of organ transplant rejection and is now an approved oncology agent.

AREAS COVERED

The objective of this review is to discuss the history of key findings and innovative cancer research undertaken to successfully develop everolimus as an oncology therapy (Afinitor) now approved for patients with advanced renal cell carcinoma (RCC) and for subependymal giant cell astrocytomas (SEGAs) associated with tuberous sclerosis. In addition, data for the use of everolimus in the treatment of other cancers and rare diseases are also discussed. A PubMed search of English articles without time restrictions was conducted using the search terms 'everolimus or rapamycin' and 'cancer'. Bibliographies of retrieved articles were manually searched for additional relevant articles. Major cancer congresses were also searched.

EXPERT OPINION

The clinical efficacy of everolimus alone and in combination with other agents has been observed in recently completed Phase II-III studies in a wide spectrum of tumors, including RCC, neuroendocrine tumors, tuberous sclerosis complex, SEGAs and angiomyolipomas, lymphoma and gastric, breast and hepatocellular cancers. These findings emphasize the importance of mTOR in diverse cancers and rare diseases and underscore the potential role for everolimus as an effective agent in multiple indications.

Everolimus: a new mammalian target of rapamycin inhibitor for the treatment of advanced renal cell carcinoma

OBJECTIVE

To review clinical trials and main characteristics of everolimus, with focus on treatment of advanced renal cell carcinoma.

DATA SOURCES

Pertinent data were identified primarily through a search of MEDLINE and PubMed (1966-November 2010) using the primary search terms everolimus, RAD001, renal cell carcinoma, and mTOR inhibitors.

STUDY SELECTION AND DATA EXTRACTION

Studies evaluating the safety and efficacy of everolimus in patients with cancer were evaluated, including Phase 1, 2, and 3 trials. Preference was given to Phase 2 and 3 studies evaluating use of everolimus in patients with renal cell carcinoma.

DATA SYNTHESIS

Everolimus is an oral mammalian target of rapamycin (mTOR) inhibitor approved for the management of patients with advanced renal cell carcinoma who progressed on tyrosine kinase inhibitor therapy. Actions of everolimus within the mTOR pathway result in decreased protein synthesis and cell cycle arrest, as well as decreased angiogenesis. A usual starting dose for patients with renal cell carcinoma is 10 mg daily. Everolimus undergoes extensive hepatic metabolism, primarily through the CYP3A4 isoenzyme, which predisposes it to drug interactions with inducers and inhibitors of this enzyme. Most commonly reported adverse events associated with everolimus include anemia, hyperglycemia, hypercholesterolemia, mucositis, fatigue, and rash. Approval of everolimus was based on the results of a Phase 3 trial that demonstrated an increase in median progression-free survival by 2.1 months in patients receiving everolimus therapy as compared to placebo. The drug was recently added to the National Comprehensive Cancer Network guidelines as a treatment option for patients with advanced renal cell carcinoma who have progressed on tyrosine kinase therapy.

CONCLUSIONS

Based on a review of the currently available literature, everolimus provides a safe and efficacious treatment option for patients with renal cell carcinoma who have progressed on treatment with sunitinib and/or sorafenib.

Mammalian target of rapamycin: hitting the bull's-eye for neurological disorders

The mammalian target of rapamycin (mTOR) and its associated cell signaling pathways have garnered significant attention for their roles in cell biology and oncology. Interestingly,the explosion of information in this field has linked mTOR to neurological diseases with promising initial studies. mTOR, a 289 kDa serine/threonine protein kinase, plays an important role in cell growth and proliferation and is activated through phosphorylation in response to growth factors, mitogens and hormones. Growth factors, amino acids, cellular nutrients and oxygen deficiency can downregulate mTOR activity. The function of mTOR signaling is mediated primarily through two mTOR complexes: mTORC1 and mTORC2. mTORC1 initiates cap-dependent protein translation, a rate-limiting step of protein synthesis, through the phosphorylation of the targets eukaryotic initiation factor 4E-binding protein 1 (4EBP1) and p70 ribosomal S6 kinase (p70S6K). In contrast, mTORC2 regulates development of the cytoskeleton and also controls cell survival. Although closely tied to tumorigenesis, mTOR and the downstream signaling pathways are significantly involved in the central nervous system (CNS) with synaptic plasticity, memory retention, neuroendocrine regulation associated with food intake and puberty and modulation of neuronal repair following injury. The signaling pathways of mTOR also are believed to be a significant component in a number of neurological diseases, such as Alzheimer disease, Parkinson disease and Huntington disease, tuberous sclerosis, neurofibromatosis, fragile X syndrome, epilepsy, traumatic brain injury and ischemic stroke. Here we describe the role of mTOR in the CNS and illustrate the potential for new strategies directed against neurological disorders.

Updates of mTOR inhibitors

Mammalian target of rapamycin (mTOR) is a central controller of cell growth, proliferation, metabolism and angiogenesis. mTOR signaling is often dysregulated in various human diseases and thus attracts great interest in developing drugs that target mTOR. Currently it is known that mTOR functions as two complexes, mTOR complex 1/2 (mTORC1/2). Rapamycin and its analogs (all termed rapalogs) first form a complex with the intracellular receptor FK506 binding protein 12 (FKBP12) and then bind a domain separated from the catalytic site of mTOR, blocking mTOR function. Rapalogs are selective for mTORC1 and effective as anticancer agents in various preclinical models. In clinical trials, rapalogs have demonstrated efficacy against certain types of cancer. Recently, a new generation of mTOR inhibitors, which compete with ATP in the catalytic site of mTOR and inhibit both mTORC1 and mTORC2 with a high degree of selectivity, have been developed. Besides, some natural products, such as epigallocatechin gallate (EGCG), caffeine, curcumin and resveratrol, have been found to inhibit mTOR as well. Here, we summarize the current findings regarding mTOR signaling pathway and review the updated data about mTOR inhibitors as anticancer agents.

Long-term response with everolimus for metastatic renal cell carcinoma refractory to sunitinib

A 70-year-old man with metastatic renal cell carcinoma developed progressive liver metastases after 8 weeks of treatment with the multitargeted tyrosine kinase inhibitor (TKI) sunitinib. He then participated in the phase III placebo-controlled clinical trial of the oral mammalian target of rapamycin (mTOR) inhibitor everolimus, initially randomized to placebo (but had disease progression after 3 months) and crossed over to everolimus at time of unblinding. The patient had stable disease after 8 weeks (two cycles) of everolimus that was maintained until 28 months of therapy, at which time the patient had achieved a partial response. This case illustrates the potential for patients with metastatic renal cell carcinoma, a malignancy with historically poor prognosis, to derive long-term benefit from everolimus when used in a manner consistent with its approved indication (after TKI therapy with sunitinib or sorafenib).

Everolimus in the treatment of renal cell carcinoma and neuroendocrine tumors

Renal cell carcinoma (RCC) and neuroendocrine tumors (NET) are uncommon malignancies, highly resistant to chemotherapy, that have emerged as attractive platforms for evaluating novel targeted regimens. Everolimus is an oral rapamycin derivative within the mammalian target of rapamycin class of agents. Preclinical series have shown that everolimus exhibits anticancer effects in RCC and NET cell lines. A phase 3 placebo-controlled study in advanced clear-cell RCC, known as RECORD-1 (for "REnal Cell cancer treatment with Oral RAD001 given Daily"), documented that everolimus stabilizes tumor progression, prolongs progression-free survival and has acceptable tolerability in patients previously treated with the multikinase inhibitors sunitinib and/or sorafenib. Everolimus has been granted regulatory approval for use in sunitinib-pretreated and/or sorafenib-pretreated advanced RCC and incorporated into clinical practice guidelines, and the RECORD-1 safety data are being used to develop recommendations for managing clinically important adverse events in everolimus-treated patients. Ongoing clinical trials are evaluating everolimus as earlier RCC therapy (first-line for advanced disease and as neoadjuvant therapy), in non-clear-cell tumors, and in combination with various other approved or investigational targeted therapies for RCC. Regarding advanced NET, recently published phase 2 data support the ability of everolimus to improve disease control in patients with advanced NET as monotherapy or in combination with somatostatin analogue therapy, octreotide long-acting release (LAR). Forthcoming data from phase 3 placebo-controlled trials of everolimus, one focused on monotherapy for pancreatic NET and the other on combination use with octreotide LAR for patients with advanced NET and a history of carcinoid syndrome, will provide insight into its future place in NET therapy. The results of a number of ongoing phase 3 evaluations of everolimus will determine its broader applicability in treating breast cancer (in combination with chemotherapy and hormonal therapy), several advanced gastrointestinal cancers, hepatocellular carcinoma, and lymphoma (in the adjuvant setting), as well as the various lesions associated with the tuberous sclerosis complex tumor suppressor gene.

Treatment Options in Metastatic Renal Cell Carcinoma: Focus on mTOR Inhibitors

THE AGENTS CURRENTLY APPROVED FOR USE IN METASTATIC RENAL CELL CARCINOMA (MRCC) CAN BE DIVIDED BROADLY INTO TWO CATEGORIES: (1) vascular endothelial growth factor receptor (VEGFR)-directed therapies or (2) inhibitors of the mammalian target of rapamycin (mTOR). The latter category includes everolimus and temsirolimus, both approved for distinct indications in mRCC. Everolimus gained its approval on the basis of phase III data showing a benefit in progression-free survival relative to placebo in patients previously treated with sunitinib and/or sorafenib. In contrast, temsirolimus was approved on the basis of a phase III trial in treatment-naïve patients with poor-risk mRCC, demonstrating an improvement in overall survival relative to interferon-alfa. While these pivotal trials have created unique positions for everolimus and temsirolimus in current clinical algorithms, the role of mTOR inhibitors in mRCC is being steadily revised and expanded through ongoing trials testing novel sequences and combinations. The clinical development of mTOR inhibitors is outlined herein.

Everolimus: the first approved product for patients with advanced renal cell cancer after sunitinib and/or sorafenib

Everolimus (RAD001, Afinitor^® Novartis) is the first oral inhibitor of mTOR (mammalian target of rapamycin) to reach the oncology clinic. Everolimus 10 mg daily achieves complete inhibition of its target at below the maximum tolerable dose for most patients. A phase III randomized placebo-controlled trial has examined the impact of everolimus in patients with clear cell renal cancers and progressive disease on or within 6 months of the VEGFR tyrosine kinase inhibitors sunitinib and/or sorafenib. The primary endpoint of progression-free survival was increased from median 1.9 to 4.9 months (hazard ratio 0.33, P < 0.001) and 25% were still progression-free after 10 months of everolimus therapy. There was a delay in time to decline of performance status and trends to improvement in quality of life, disease-related symptoms, and overall survival despite crossover of the majority of patients assigned to placebo. In 2009, everolimus was approved in the US and Europe as the only validated option for this indication. Toxicities are usually mild to moderate and can be managed with dose reduction or interruption if necessary. Opportunistic infections and non-infectious pneumonitis are seen as a class effect. Management of common practical management issues are discussed. Clinical trials are in progress to examine additional roles for everolimus in renal cancer, alone and in combination with other agents.

Stable disease is a valid end point in clinical trials

For most clinical oncologists trained before the 1990s, a 20% or greater response rate is the convention for a drug to be considered active in phase II studies. However, this no longer holds true with several targeted therapies repeatedly achieving the regulatory criteria of progression-free and overall survival benefit with considerably lower objective response rates but a sizeable proportion of patients having stable disease. Considerable skepticism persists as to the value of stable disease as a valid outcome in early clinical trials of new agents. With a high percentage of new oncologic agents failing in phase III studies, the confidence one has in predicting later success in randomized studies when stable disease alone is observed is understandably low. Continued uncertainty of the value of stable disease is based on the lack of precision in defining this as a meaningful outcome. With the term stable disease encompassing a broad range from <20% enlargement to <30% reduction using standard response criteria response evaluation criteria in solid tumors, what one refers to as stable disease is open to diverse interpretation. The evidence that stable disease is a valid end point in many recent clinical trials is therefore discussed in this review and along with contemporary methods that bring some accuracy to the interpretation of stable disease within the context of clinical trial results.

Biomarker Development for the Clinical Activity of the mTOR Inhibitor Everolimus (RAD001): Processes, Limitations, and Further Proposals

The mTOR inhibitor everolimus (RAD001, Afinitor) is an orally active anticancer agent. Everolimus demonstrates growth-inhibitory activity against a broad range of tumor cell histotypes in vitro and has the capacity to retard tumor growth in preclinical tumor models in vivo through mechanisms directed against both the tumor cell and the solid tumor stroma components. These properties have rendered it to be a clinically active drug, with subsequent registration in renal cell carcinoma (Motzer et al. [2008]. Lancet372, 449-456) as well as showing strong potential as a combination partner (André F et al. [2008]. J Clin Oncol26. Abstract 1003). Although everolimus has a high specificity for its molecular target, the ubiquitous nature of mTOR and the multifactorial influence that mTOR signaling has on cell physiology have made studies difficult on the identification and validation of a biomarker set to predict and monitor drug sensitivity for clinical use. In this review, a summary of the preclinical and clinical data relevant to biomarker development for everolimus is presented, and the advantages and problems of current biomarkers are reviewed. In addition, alternative approaches to biomarker development are proposed on the basis of examples of a combination of markers and functional noninvasive imaging. In particular, we show how basal levels of pAKT and pS6 together could, in principle, be used to stratify patients for likely response to an mTOR inhibitor.

mTOR signaling and drug development in cancer

Mammalian target of rapamycin (mTOR) is a protein kinase of the PI3K/Akt signaling pathway. Activation of mTOR in response to growth, nutrient and energy signals leads to an increase in protein synthesis, which is required for tumor development. This feature makes mTOR an attractive target for cancer therapy. First-generation mTOR inhibitors are sirolimus derivatives (rapalogs), which have been evaluated extensively in cancer patients. Everolimus and temsirolimus are already approved for the treatment of renal-cell carcinoma. Temsirolimus is also approved for the treatment of mantle-cell lymphoma. These drugs, in addition to ridaforolimus (formerly deforolimus) and sirolimus, are currently being evaluated in clinical trials of various cancers. Second-generation mTOR inhibitors are small molecules that target the kinase domain, and have also entered clinical development. Clinical trials are underway to identify additional malignancies that respond to mTOR inhibitors, either alone or in combination with other therapies. Future research should evaluate the optimal drug regimens, schedules, patient populations, and combination strategies for this novel class of agents.

Everolimus (RAD001) in the treatment of advanced renal cell carcinoma: a review

This review describes the clinical development of everolimus in advanced renal cell carcinoma and the rationale for the use of mammalian target of rapamycin inhibitors after failure of vascular endothelial growth factor/vascular endothelial growth factor receptor inhibitors.

Historically, there have been few treatment options for patients with advanced renal cell carcinoma (RCC) besides immunotherapy with interleukin-2 and interferon (IFN)-α. Targeted therapies have improved clinical outcomes over the past several years. These include the vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors sunitinib and sorafenib, which inhibit angiogenic signaling in endothelial cells and vascular pericytes predominantly through VEGFR and platelet-derived growth factor receptor β. Also included is the anti-VEGF monoclonal antibody bevacizumab used in combination with IFN-α. These agents mediate their antitumor effects by interfering with the VEGF signaling pathway, thereby inhibiting angiogenesis and causing tumor shrinkage. However, ultimately, most patients develop resistance and experience disease progression during VEGF/VEGFR-targeted therapy, and until the recent approval of the mammalian target of rapamycin (mTOR) inhibitor everolimus (RAD001), there were no agents available with proven activity in this setting. This review describes the clinical development of everolimus in advanced RCC and the rationale for the use of mTOR inhibitors after failure of VEGF/VEGFR inhibitors.

Acute cholecystitis in a patient with metastatic renal cell carcinoma treated with everolimus

Everolimus (RAD001) is an orally administered inhibitor of the mammalian target of rapamycin (mTOR), a therapeutic target for metastatic renal cell carcinoma. A 58-year-old woman was treated with everolimus as a third-line therapy for metastatic clear-cell renal carcinoma. She was given oral everolimus 10 mg once daily. During the fourth week of her first cycle, the patient was admitted to our hospital because of an acute-onset, right upper quadrant pain associated with nausea and vomiting. She was diagnosed with acute cholecystitis, which was treated with broad-spectrum antibiotics, and everolimus therapy was discontinued. A follow-up computed tomography scan of the abdomen revealed a complete resolution of gallbladder changes. Our patient did not have major risk factors for developing a cholecystitis except for a relative immunosuppressed state secondary to her advanced renal cancer. The Naranjo adverse drug reaction probability scale score for this event was 5, indicating a probable association of the event with everolimus. Because the use of everolimus is expanding in clinical practice, we want to alert the oncology community about this uncommon and life-threatening complication in patients receiving everolimus or another agent with antiangiogenic activity. To our best knowledge, only one case of an acute cholangitis associated with everolimus in a metastatic renal cell carcinoma has been reported. We report herein the first case of a metastatic renal cell carcinoma developed everolimus-associated cholecystitis that was completely reversed after drug withdrawal.

mTOR pathway inhibition in renal cell carcinoma

Renal cell carcinoma therapy has changed in a very significant way in the last few years. Up to 5 new agents have been developed, improving the results previously achieved with cytokine therapy. Bevacizumab, sorafenib, sunitinib, temsirolimus, and everolimus are now part of the therapeutic arsenal for this illness. Particularly, this has been the first tumoral type in which inhibition of mammalian target of rapamycin (mTOR) has proved its efficacy in phase III trials, either as first-line therapy for poor prognosis patients (temsirolimus, CCI-779) or as second-line therapy after failure of tyrosine-kinase inhibitors (everolimus, RAD001). In this paper, we review the basis for mTOR inhibition in RCC, and discuss the results of the trials involving temsirolimus and everolimus for the treatment of this disease.

Noninfectious pneumonitis after everolimus therapy for advanced renal cell carcinoma

RATIONALE

Noninfectious pneumonitis is a known class effect of mammalian target of rapamycin (mTOR) inhibitors.

OBJECTIVES

To assess the incidence, radiographic patterns, management, and outcome of pneumonitis in patients with advanced renal cell carcinoma receiving everolimus.

METHODS

Clinical study data from 416 patients, randomized to receive everolimus versus placebo, were analyzed for adverse events of pneumonitis. Radiographic studies performed every 8 weeks were subject to a prospective, independent, blinded central review for the presence of findings indicative of pneumonitis.

MEASUREMENTS AND MAIN RESULTS

Of 274 patients receiving everolimus, clinical pneumonitis was suspected for 37 patients (13.5%) (none with placebo). Nine cases (3.3%) were grade 1 (asymptomatic), 18 (6.6%) were grade 2 (not interfering with daily living), and 10 (3.6%) were grade 3 (interfering with daily living or oxygen indicated). No grade 4 (life-threatening) pneumonitis was observed. Of the 10 patients with grade 3 pneumonitis, 5 had baseline radiological evidence of pneumonitis before everolimus therapy. Twenty of the 37 cases (54.0%) were reversible within the follow-up period; resolution followed dose reduction for 20 patients and treatment discontinuation in 10 patients. Corticosteroid therapy was initiated in 16 cases. Dedicated radiological review of available serial radiographic studies (245 patients receiving everolimus and 132 receiving placebo) found a higher percentage of new radiographic findings even in patients without a diagnosis of clinical pneumonitis who were receiving everolimus versus placebo (38.9 vs. 15.2%).

CONCLUSIONS

Early recognition, prompt intervention, and a conservative approach are important in managing the risk associated with noninfectious pneumonitis in association with everolimus. Clinical trial registered with www.clinicaltrials.gov (NCT 00410124).

Metastatic Renal Cancer: What Role for Everolimus?

Metastatic renal cell carcinoma is uncommon (only 3% of cancers worldwide) but of poor prognosis. Renal cell carcinoma has traditionally been treated with cytokines (interferon-α or interleukin-2). More recently, a more clear understanding of the molecular and cellular mechanisms of the disease, involving the VEGF receptor and mTOR, has led to the discovery of novel therapies. Therapeutic options in patients with advanced RCC include the VEGF receptor inhibitors Sunitinib and Sorafenib, the anti-VEGF monoclonal antibody Bevacizumab and the mTORC1 inhibitors Temsirolimus and Everolimus. In 2009, Everolimus was FDA-approved for the treatment of patients with advanced clear cell RCC which had progressed within 6 months of stopping treatment with Sunitinib or sorafenib, or both drugs. Everolimus resulted in a 70% reduction in the risk of disease recurrence or death. The purpose of this review is to update on the current knowledge of the role of Everolimus in metastatic renal cell carcinoma.

NUB1, an interferon-inducible protein, mediates anti-proliferative actions and apoptosis in renal cell carcinoma cells through cell-cycle regulation

Background:

NEDD8 ultimate buster 1 (NUB1) is an interferon (IFN)-inducible protein that downregulates NEDD8 expression and its conjugation system. Although overexpression of NUB1 induces a growth-inhibitory effect in cells, the mechanisms underlying the anti-mitogenic actions of NUB1 in cancer cells remain uncertain. We investigated the anti-cancer effects of NUB1 in human renal cell carcinoma (RCC) cells.

Methods:

Nine human RCC cells were used for this study. The proliferation of RCC cells exposed to IFN-α was measured by water-soluble tetrazolium salt assay. The expression level of NUB1 in cells was measured by quantitative reverse transcriptase PCR or western blot analysis. Apoptosis and cell-cycle analysis were performed by flow cytometry. Silencing of NUB1 was performed using a small interfering RNA.

Results:

Both NUB1 messenger RNA and protein were significantly induced by IFN-α in seven out of nine selected RCC cell lines, and the NUB1 expressions induced by IFN-α correlated positively with cell growth inhibition. Overexpression of NUB1 remarkably induced S-phase transition during cell cycle and apoptosis in IFN-α-resistant A498 cells, in which NUB1 is not induced by IFN-α. The expression levels of two cell-cycle regulator proteins, cyclin E and p27, were increased under the aforementioned conditions. The knockdown of NUB1 enhanced cell proliferation of IFN-α-resistant A498 cells and suppressed IFN-α-induced growth inhibition in IFN-α-sensitive 4TUHR cells.

Conclusion:

NUB1 may be a key factor involved not only in cell growth inhibition by IFN-α in RCC cells but also in the anti-cancer effect against IFN-α-resistant RCC cells.

Safety and clinical efficacy of everolimus in the treatment of advanced renal cell carcinoma (RCC)

Renal cell carcinoma (RCC) is one of the most lethal genitourinary malignancies. Recently, there has been a paradigm shift in the management of advanced RCC. New targeted therapies including vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) inhibitors have been developed which have shown promising results in a patient population who otherwise had very few options for treatment. The first mTOR inhibitor, temsirolimus, an intravenous prodrug, has shown improved overall survival in poor prognosis patients. More recently, an oral mTOR inhibitor, everolimus (RAD 001), has been developed which has been shown to delay disease progression in patients with metastatic RCC who have progressed on other targeted therapies. Although a survival advantage in phase III trials is seen with everolimus, associated systemic toxicities, while generally well tolerated, are not insignificant. These include mucositis, hyperglycemia, hyperlipidemia, and pneumonitis. Despite the side effects, emerging evidence points to everolimus as the optimal second-line treatment for patients with advanced renal cell carcinoma.