Randomized phase II study of multiple dose levels of CCI-779, a novel mammalian target of rapamycin kinase inhibitor, in patients with advanced refractory renal cell carcinoma

microRNA-21 governs TORC1 activation in renal cancer cell proliferation and invasion

Metastatic renal cancer manifests multiple signatures of gene expression. Deviation in expression of mature miRNAs has been linked to human cancers. Importance of miR-21 in renal cell carcinomas is proposed from profiling studies using tumor tissue samples. However, the role of miR-21 function in causing renal cancer cell proliferation and invasion has not yet been shown. Using cultured renal carcinoma cells, we demonstrate enhanced expression of mature miR-21 along with pre-and pri-miR-21 by increased transcription compared to normal proximal tubular epithelial cells. Overexpression of miR-21 Sponge to quench endogenous miR-21 levels inhibited proliferation, migration and invasion of renal cancer cells. In the absence of mutation in the PTEN tumor suppressor gene, PTEN protein levels are frequently downregulated in renal cancer. We show that miR-21 targets PTEN mRNA 3'untranslated region to decrease PTEN protein expression and augments Akt phosphorylation in renal cancer cells. Downregulation of PTEN as well as overexpression of constitutively active Akt kinase prevented miR-21 Sponge-induced inhibition of renal cancer cell proliferation and migration. Moreover, we show that miR-21 Sponge inhibited the inactivating phosphorylation of the tumor suppressor protein tuberin and attenuated TORC1 activation. Finally, we demonstrate that expression of constitutively active TORC1 attenuated miR-21 Sponge-mediated suppression of proliferation and migration of renal cancer cells. Our results uncover a layer of post-transcriptional regulation of PTEN by transcriptional activation of miR-21 to force the canonical oncogenic Akt/TORC1 signaling conduit to drive renal cancer cell proliferation and invasion.

The role of mTOR inhibitors in the inhibition of growth and cortisol secretion in human adrenocortical carcinoma cells

Patients with adrenocortical carcinoma (ACC) need new treatment options. The aim of this study was to evaluate the effects of the mTOR inhibitors sirolimus and temsirolimus on human ACC cell growth and cortisol production. In H295, HAC15, and SW13 cells, we have evaluated mTOR, IGF2, and IGF1 receptor expressions; the effects of sirolimus and temsirolimus on cell growth; and the effects of sirolimus on apoptosis, cell cycle, and cortisol production. Moreover, the effects of sirolimus on basal and IGF2-stimulated H295 cell colony growth and on basal and IGF1-stimulated phospho-AKT, phospho-S6K1, and phospho-ERK in H295 and SW13 were studied. Finally, we have evaluated the effects of combination treatment of sirolimus with an IGF2-neutralizing antibody. We have found that H295 and HAC15 expressed IGF2 at a >1800-fold higher level than SW13. mTOR inhibitors suppressed cell growth in a dose-/time-dependent manner in all cell lines. SW13 were the most sensitive to these effects. Sirolimus inhibited H295 colony surviving fraction and size. These effects were not antagonized by IGF2, suggesting the involvement of other autocrine regulators of mTOR pathways. In H295, sirolimus activated escape pathways. The blocking of endogenously produced IGF2 increased the antiproliferative effects of sirolimus on H295. Cortisol production by H295 and HAC15 was inhibited by sirolimus. The current study demonstrates that mTOR inhibitors inhibit the proliferation and cortisol production in ACC cells. Different ACC cells have different sensitivity to the mTOR inhibitors. mTOR could be a target for the treatment of human ACCs, but variable responses might be expected. In selected cases of ACC, the combined targeting of mTOR and IGF2 could have greater effects than mTOR inhibitors alone.

The class I PI3K/Akt pathway is critical for cancer cell survival in dogs and offers an opportunity for therapeutic intervention

BACKGROUND

Using novel small-molecular inhibitors, we explored the feasibility of the class I PI3K/Akt/mTORC1 signaling pathway as a therapeutic target in canine oncology either by using pathway inhibitors alone, in combination or combined with conventional chemotherapeutic drugs in vitro.

RESULTS

We demonstrate that growth and survival of the cell lines tested are predominantly dependent on class I PI3K/Akt signaling rather than mTORC1 signaling. In addition, the newly developed inhibitors ZSTK474 and KP372-1 which selectively target pan-class I PI3K and Akt, respectively, and Rapamycin which has been well-established as highly specific mTOR inhibitor, decrease viability of canine cancer cell lines. All inhibitors demonstrated inhibition of phosphorylation of pathway members. Annexin V staining demonstrated that KP372-1 is a potent inducer of apoptosis whereas ZSTK474 and Rapamycin are weaker inducers of apoptosis. Simultaneous inhibition of class I PI3K and mTORC1 by ZSTK474 combined with Rapamycin additively or synergistically reduced cell viability whereas responses to the PI3K pathway inhibitors in combination with conventional drug Doxorubicin were cell line-dependent.

CONCLUSION

This study highlighted the importance of class I PI3K/Akt axis signaling in canine tumour cells and identifies it as a promising therapeutic target.

Sustained antitumor activity by co-targeting mTOR and the microtubule with temsirolimus/vinblastine combination in hepatocellular carcinoma

The mammalian target of rapamycin (mTOR) and the microtubules are prominent druggable targets for hepatocellular carcinoma (HCC). PI3K/Akt/mTOR activation is associated with resistance to microtubule inhibitors. Here, we hypothesized that co-targeting of mTOR (by mTOR inhibitor temsirolimus) and the microtubule (by microtubule-destabilizing agent vinblastine) would be more efficacious than single targeting in HCC models. In vitro studies showed that effective inhibition of mTOR signaling with temsirolimus alone was able to suppress HCC cell growth in a dose-dependent manner. Among five cell lines tested, Huh7 was the most temsirolimus-sensitive (IC(50)=1.27±0.06μM), while Hep3B was the most temsirolimus-resistant (IC(50)=52.95±17.14μM). We found that co-targeting of mTOR (by temsirolimus) and the microtubule (by vinblastine, at low nM) resulted in marked growth inhibition in Huh7 cells and synergistic growth inhibition in Hep3B cells (achieving maximal growth inhibition of 80-90%), demonstrating potent antitumor activity of this novel combination. In vivo studies showed that temsirolimus treatment alone for 1 week was able to inhibit the growth of Huh7 xenografts. Strikingly, the temsirolimus/vinblastine combination induced a significant and sustained antitumor activity (up to 27 days post-treatment), with effective reduction of tumor vessel density in both Huh7 and Hep3B xenograft models. Mechanistic investigation revealed that this marked antitumor effect was accompanied by specific and concerted down-regulation of several key anti-apoptotic/survival proteins (survivin, Bcl-2, and Mcl-1), which was not observed in single agent treatments. Our findings demonstrated that the potent anti-cancer activity of this co-targeting strategy was indeed mediated in parts by inhibition of these key survival/anti-apoptotic proteins.

Pneumonitis associated with mTOR inhibitors therapy in patients with metastatic renal cell carcinoma: incidence, radiographic findings and correlation with clinical outcome

BACKGROUND

Mammalian target of rapamycin (mTOR) inhibitors are approved for use in patients with metastatic renal cell carcinoma (mRCC) and are under investigation in several other malignancies. We assessed the incidence, clinical presentation and computed tomography (CT) findings of pneumonitis associated with mTOR inhibitors in mRCC. Correlation between radiological findings of pneumonitis and clinical outcome was also determined.

METHODS

We retrospectively reviewed the clinical data and serial CT scans from patients with mRCC treated with either temsirolimus or everolimus. Serial chest CT scans were reviewed in consensus, read by two independent radiologists for the presence of pneumonitis, and corresponding clinical data were reviewed for symptoms and clinical outcome. The baseline and follow up CTs were reviewed to assess outcome to therapy.

RESULTS

The study population consisted of 46 pts, 21 treated with temsirolimus and 25 with everolimus (M:F 2.5:1; median 63 years, range 31-79 years). CT evidence of pneumonitis was seen in 14/46 pts (30%), at a median of 56days on mTOR inhibitor treatment (range 31-214 days). Respiratory symptoms at the time of radiographically detected pneumonitis, were observed in 7pts. Stable disease (SD) by Response Evaluation Criteria in Solid Tumours (RECIST) was achieved in 12/14 pts (86%) who developed radiographic pneumonitis compared to 14/32 (44%) without pneumonitis (p=0.01) The mean change of tumour long axis size for target lesions by RECIST, normalised for 30 days on therapy was -2.9% in the pneumonitis group and +4.3% in the non-pneumonitis group (p=.002).

CONCLUSIONS

Preliminary data suggest that pneumonitis may be a marker of stable disease by RECIST and therefore, of therapeutic benefit. Careful patient assessment should be undertaken before the drug is discontinued.

DNA-PK mediates AKT activation and apoptosis inhibition in clinically acquired platinum resistance

Clinical resistance to chemotherapy is a frequent event in cancer treatment and is closely linked to poor outcome. High-grade serous (HGS) ovarian cancer is characterized by p53 mutation and high levels of genomic instability. Treatment includes platinum-based chemotherapy and initial response rates are high; however, resistance is frequently acquired, at which point treatment options are largely palliative. Recent data indicate that platinum-resistant clones exist within the sensitive primary tumor at presentation, implying resistant cell selection after treatment with platinum chemotherapy. The AKT pathway is central to cell survival and has been implicated in platinum resistance. Here, we show that platinum exposure induces an AKT-dependent, prosurvival, DNA damage response in clinically platinum-resistant but not platinum-sensitive cells. AKT relocates to the nucleus of resistant cells where it is phosphorylated specifically on S473 by DNA-dependent protein kinase (DNA-PK), and this activation inhibits cisplatin-mediated apoptosis. Inhibition of DNA-PK or AKT, but not mTORC2, restores platinum sensitivity in a panel of clinically resistant HGS ovarian cancer cell lines: we also demonstrate these effects in other tumor types. Resensitization is associated with prevention of AKT-mediated BAD phosphorylation. Strikingly, in patient-matched sensitive cells, we do not see enhanced apoptosis on combining cisplatin with AKT or DNA-PK inhibition. Insulin-mediated activation of AKT is unaffected by DNA-PK inhibitor treatment, suggesting that this effect is restricted to DNA damage-mediated activation of AKT and that, clinically, DNA-PK inhibition might prevent platinum-induced AKT activation without interfering with normal glucose homeostasis, an unwanted toxicity of direct AKT inhibitors.

Neurotoxicity of biologically targeted agents in pediatric cancer trials

Biologically targeted agents offer the promise of delivering specific anticancer effects while limiting damage to healthy tissue, including the central and peripheral nervous systems. During the past 5-10 years, these agents were examined in preclinical and adult clinical trials, and are used with increasing frequency in children with cancer. This review evaluates current knowledge about neurotoxicity from biologically targeted anticancer agents, particularly those in pediatric clinical trials. For each drug, neurotoxicity data are reviewed in adult (particularly studies of brain tumors) and pediatric studies when available. Overall, these agents are well tolerated, with few serious neurotoxic effects. Data from younger patients are limited, and more neurotoxicity may occur in the pediatric population because these agents target pathways that control not only tumorigenesis but also neural maturation. Further investigation is needed into long-term neurologic effects, particularly in children.

[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.

Relapsed and/or Refractory Mantle Cell Lymphoma: What Role for Temsirolimus?

Mantle Cell Lymphoma (MCL) is associated with a dismal prognosis. Recently, along with the improved understanding of the pathophysiology of this disease, new first line regimens have been established and in addition novel treatment options have entered the clinical arena. In consequence, prognosis of the disease has fortunately improved. We here focus on the rationale, current clinical knowledge and future concepts of Temsirolimus, an inhibitor of mTOR, in the treatment of MCL. At this time this drug has been shown to be effective as single agent for relapsed disease and early combination data show promising results. In addition, with a brief outline of other treatment options, we aim to guide at which place in the current treatment algorithms Temsirolimus can be integrated into the treatment of MCL patients.

Biologic rationale and clinical activity of mTOR inhibitors in gynecological cancer

Advanced recurrent gynecological malignancies have a poor prognosis despite systemic treatment, which is usually cytotoxic chemotherapy. Responses are generally short-lived and more effective treatments are needed. Rationally designed molecularly targeted therapy is an emerging and important option in this setting. The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase of the phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathway with a critical role in controlling cancer cellular growth, metabolism and cell cycle progression. Aberrant PI3K-dependent signaling occurs frequently in a wide range of tumor types, including ovarian, endometrial and cervical cancer. Early clinical studies of first-generation mTOR inhibitors have shown promising clinical activity in endometrial cancer. However, the molecular basis of sensitivity and resistance to these agents remains largely unknown. In this review, we will update the clinical and biological data underlying the development of first generation mTOR inhibitors in the treatment of gynecological tumors. The role of potential new combination regimens with mTOR inhibitors in gynecological cancers will also be discussed.

The PIM kinases in hematological cancers

The PIM genes represent a family of proto-oncogenes that encode three different serine/threonine protein kinases (PIM1, PIM2 and PIM3) with essential roles in the regulation of signal transduction cascades, which promote cell survival, proliferation and drug resistance. PIM kinases are overexpressed in several hematopoietic tumors and support in vitro and in vivo malignant cell growth and survival, through cell cycle regulation and inhibition of apoptosis. PIM kinases do not have an identified regulatory domain, which means that these proteins are constitutively active once transcribed. They appear to be critical downstream effectors of important oncoproteins and, when overexpressed, can mediate drug resistance to available agents, such as rapamycin. Recent crystallography studies reveal that, unlike other kinases, they possess a hinge region, which creates a unique binding pocket for ATP, offering a target for an increasing number of potent small-molecule PIM kinase inhibitors. Preclinical studies in models of various hematologic cancers indicate that these novel agents show promising activity and some of them are currently being evaluated in a clinical setting. In this review, we profile the PIM kinases as targets for therapeutics in hematologic malignancies.

An international expanded-access programme of everolimus: addressing safety and efficacy in patients with metastatic renal cell carcinoma who progress after initial vascular endothelial growth factor receptor-tyrosine kinase inhibitor therapy

BACKGROUND AND OBJECTIVES

The RECORD-1 trial established the clinical benefit of everolimus in patients with metastatic renal cell carcinoma (mRCC) after failure of initial vascular endothelial growth factor receptor-tyrosine kinase inhibitor (VEGFr-TKI) therapy. The REACT (RAD001 Expanded Access Clinical Trial in RCC) study was initiated to address an unmet medical need by providing everolimus prior to commercial availability, and also to further assess the safety and efficacy of everolimus in patients with VEGFr-TKI-refractory mRCC.

PATIENTS AND METHODS

REACT (Clinicaltrials.gov: NCT00655252) was a global, open-label, expanded-access programme in patients with mRCC who were intolerant of, or who had progressed on or after stopping treatment with, any available VEGFr-TKI therapy. Patients received everolimus 10mg once daily, with dose and schedule modifications allowed for toxicity. Patients were closely monitored for the development of serious and grades 3/4 adverse events (AEs). Response was assessed by RECIST every 3months for the first year and every 6months thereafter.

RESULTS

A total of 1367 patients were enroled. Safety findings and tumour responses were consistent with those observed in RECORD-1, with no new safety issues identified. The most commonly reported serious AEs were dyspnoea (5.0%), pneumonia (4.7%) and anaemia (4.1%), and the most commonly reported grades 3/4 AEs were anaemia (13.4%), fatigue (6.7%) and dyspnoea (6.5%). Best overall response was stable disease in 51.6% and partial response in 1.7% of patients. Median everolimus treatment duration was 14weeks.

CONCLUSION

Everolimus is well tolerated in patients with mRCC and demonstrates a favourable risk-benefit ratio.

Randomized study of autologous cytokine-induced killer cell immunotherapy in metastatic renal carcinoma

PURPOSE

The therapeutic benefit of the cytokine-induced killer (CIK) cells was unknown in the renal cell carcinoma (RCC). This prospectively randomized study was conducted to evaluate the effects of autologous CIK cell immunotherapy in patients with metastatic clear cell RCCs.

EXPERIMENTAL DESIGN

From June 2005 to June 2008, 148 patients with metastatic clear cell RCC were randomized to autologous CIK cell immunotherapy (arm 1, n = 74), or interleukin-2 treatment combination with IFN-α-2a (arm 2, n = 74). The primary endpoint was overall survival (OS) and secondary endpoint was progression-free survival (PFS) evaluated by Kaplan-Meier analyses and treatment HRs with the Cox proportional hazards model.

RESULTS

The 3-year PFS and OS in arm 1 were 18% and 61%, as compared with 12% and 23% in arm 2 (P = 0.031 and <0.001, respectively). The median PFS and OS in arm 1 were significantly longer than those in arm 2 (PFS, 12 vs. 8 months, P = 0.024; OS, 46 vs. 19 months, P < 0.001). Multivariate analyses indicated that the cycle count of CIK cell immunotherapy as a continuous variable was significantly associated with prolonged PFS [HR = 0.88; 95% confidence interval (CI), 0.84-0.93; P < 0.001] and OS (HR = 0.58; 95% CI, 0.48-0.69; P < 0.001) in arm 1.

CONCLUSION

The data suggested that CIK cell immunotherapy could improve the prognosis of metastatic clear cell RCC, and increased cycle count of CIK cell treatment could further enhance the beneficial effects.

Enhanced apoptosis and tumor growth suppression elicited by combination of MEK (selumetinib) and mTOR kinase inhibitors (AZD8055)

The mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase/AKT signaling pathways interact at multiple nodes in cancer, including at mTOR complexes, suggesting an increased likelihood of redundancy and innate resistance to any therapeutic effects of single pathway inhibition. In this study, we investigated the therapeutic effects of combining the MAPK extracellular signal-regulated kinase (MEK)1/2 inhibitor selumetinib (AZD6244) with the dual mTORC1 and mTORC2 inhibitor (AZD8055). Concurrent dosing in nude mouse xenograft models of human lung adenocarcinoma (non-small cell lung cancers) and colorectal carcinoma was well tolerated and produced increased antitumor efficacy relative to the respective monotherapies. Pharmacodynamic analysis documented reciprocal pathway inhibition associated with increased apoptosis and Bim expression in tumor tissue from the combination group, where key genes such as DUSP6 that are under MEK functional control were also modulated. Our work offers a strong rationale to combine selumetinib and AZD8055 in clinical trials as an attractive therapeutic strategy.

Managing stomatitis in patients treated with Mammalian target of rapamycin inhibitors

Mammalian target of rapamycin (mTOR) inhibitors are a class of targeted cancer therapeutic agents with clinical benefit for multiple tumor types. Oral ulcerations are a common side effect of mTOR inhibitors; however, the clinical findings resemble aphthous stomatitis rather than the mucositis seen with chemotherapy. Consequently, the appearance of aphthous-like oral ulcerations has been referred to as mTOR inhibitor-associated stomatitis (mIAS). The severity of mIAS can be minimized by following common preventive steps and initiating treatment at the first sign of mouth discomfort, thereby reducing the likelihood of treatment discontinuation. mIAS can be managed through prophylactic measures, such as patient education in oral hygiene and avoidance of triggers. Patients who develop mIAS may be treated topically using rinses or other local therapies, including corticosteroids. In severe cases, dose modifications may be required. Oncology nurses have an important role in the management of patients with cancer and are well positioned to offer strategies for minimizing the occurrence and impact of mIAS.

Predictors of response to targeted therapy in renal cell carcinoma

CONTEXT

The prognosis for patients with metastatic renal cell carcinoma is poor, with an average 5-year survival of approximately 10%. Use of traditional cytokine therapy, specifically high-dose interleukin 2, is limited by significant toxicity. Better understanding of the molecular pathogenesis of renal cell carcinoma has led to the development of targeted therapies to inhibit specific cellular pathways leading to tumorigenesis. These drugs provide improved survival with a more favorable toxicity profile. There is ongoing investigation of markers that predict response of an individual patient to different targeted therapies.

OBJECTIVE

To explain the molecular basis for vascular endothelial growth factor inhibitor (antiangiogenic) and mammalian target of rapamycin inhibitor therapies for renal cell carcinoma, summarize the clinical trials demonstrating the effectiveness of these drugs, and describe the biomarkers shown to correlate with outcome in patients treated with targeted therapy.

DATA SOURCES

All included sources are from peer-reviewed journals in PubMed (US National Library of Medicine).

CONCLUSION

Emerging evidence shows promise that biomarkers will be useful for predicting an individual patient's response to targeted therapy, leading to a more personalized approach to treating renal cell carcinoma.

Temsirolimus in combination with carboplatin and paclitaxel in patients with advanced solid tumors: a NCIC-CTG, phase I, open-label dose-escalation study (IND 179)

BACKGROUND

The purpose of the study was to assess the safety, tolerability, recommended phase II dose (RPTD), and preliminary antitumor activity of the combination of carboplatin-paclitaxel (Taxol)-temsirolimus.

MATERIALS AND METHODS

Patients with solid malignancies suitable for carboplatin-paclitaxel (CP) chemotherapy and two or less prior lines of chemotherapy received 15, 20, or 25 mg of temsirolimus per week with CP given every 21 days. Thirty-eight eligible patients were entered into six dose levels with the first two levels administering temsirolimus on days 8 and 15 and the subsequent four dose levels switching to days 1 and 8 temsirolimus administration.

RESULTS

Days 8 and 15 administration of temsirolimus was not feasible due to myelosuppression on day 15. CP on day 1 with temsirolimus on days 1 and 8 was well tolerated. Dose-limiting toxicity (DLT) was grade 4 thrombocytopenia (n=2) and grade 3 fatigue (n=1). Relative dose intensities for carboplatin, paclitaxel, and temsirolimus at the RPTD were 92%, 82%, and 56%, respectively. Non-DLT treatment-related adverse events occurring in >20% of patients included fatigue, mucositis, alopecia, neuropathy, nausea, neutropenia, thrombocytopenia, and infection. Grade 3/4 non-hematological toxicity was rare. Partial responses (PRs) and disease stabilization were seen in 46% and 49% of patients, respectively. Nine of 11 (82%) endometrial cancer patients had objective PRs.

CONCLUSION

Carboplatin-paclitaxel-temsirolimus is well tolerated and the RPTD is carboplatin area under the curve 5 mg/ml/min, paclitaxel 175 mg/m2, both given on day 1 with temsirolimus 25 mg on days 1 and 8.

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.

Safety and efficacy of temsirolimus in heavily pretreated patients with metastatic renal cell carcinoma

BACKGROUND

First line treatment with temsirolimus is considered standard of care in poor risk patients with metastatic renal cell carcinoma. The role of temsirolimus in pretreated patients with any risk profile is unclear. The aim of this retrospective analysis was to investigate the impact of temsirolimus in patients who had progressed on various treatment lines.

MATERIAL AND METHODS

From April 2007 to July 2009, all patients who had progressed on receptor-tyrosine kinase-inhibitors, VEGF-antibodies and other agents were treated with temsirolimus (25 mg weekly). Physical examination, white blood cell count and chemistry were obtained weekly and tumor response was assessed every 12 weeks.

RESULTS

Thirty patients with a median age of 68 years range (44-81) received treatment with temsirolimus. Most patients were categorized intermediate risk (60%) and the majority had three or more metastatic sites (56.7%). Temsirolimus was median the fourth (range 2-5) systemic treatment line. Grade 3 and 4 toxicities were rare and consisted of anemia, thrombocytopenia and hyperglycemia. Objective remission and stable disease were achieved in 13.3% and 60% of the patients, respectively. The median progression free survival was 4.9 months (2.93-6.81 95% CI).

CONCLUSION

Temsirolimus appears feasible, safe and active in heavily pretreated patients.

LY294002 and metformin cooperatively enhance the inhibition of growth and the induction of apoptosis of ovarian cancer cells

BACKGROUND

The phosphoinositide 3 kinase (PI3K)/v-akt murine thymoma viral oncogene homolog (AKT)/mammalian target of rapamycin (mTOR) pathway is frequently aberrantly activated in ovarian cancer and confers the chemoresistant phenotype of ovarian cancer cells. LY294002 (PI3K inhibitor) and metformin (5'-adenosine monophosphate [AMP]-activated protein kinase [AMPK] activator) are 2 drugs that were known to inhibit mTOR expression through the AKT-dependent and AKT-independent pathways, respectively. In this study, we explored the effectiveness of LY294002 and metformin in combination on inhibition of ovarian cancer cell growth.

METHODS

Western blotting was used to detect the changes of PI3K/AKT/mTOR and AMPK/acetyl-CoA carboxylase (ACC) signaling activities, cell cycle control, and apoptosis. Cell growth was evaluated by cell proliferation, colony formation, and soft agar assays. Flow cytometry was used to study cell cycle distribution and cell death upon drug treatment.

RESULTS

Our study showed that LY294002 and metformin in combination could simultaneously enhance the repression of the PI3K/AKT/mTOR pathway and the activation of the AMPK/ACC pathway. The downstream target of AKT and AMPK, mTOR, was cooperatively repressed when the drugs were used together. The cell cycle regulatory factors, p53, p27, and p21, were up-regulated. On the other hand, caspase 3 and poly (ADP-ribose) polymerase activities involved in apoptosis were also activated. Cell growth assays indicated that LY294002 and metformin could effectively inhibit ovarian cancer cell growth. Flow cytometry analysis showed that the treatment of the 2 drugs mentioned above induced cell cycle arrest at G1 phase and increased sub-G1 apoptotic cells.

CONCLUSION

The combinational use of LY294002 and metformin can enhance inhibition of the growth and induction of the apoptosis of ovarian cancer cells. Our results may provide significant insight into the future therapeutic regimens in ovarian cancer.

Everolimus in metastatic renal cell carcinoma: Subgroup analysis of patients with 1 or 2 previous vascular endothelial growth factor receptor-tyrosine kinase inhibitor therapies enrolled in the phase III RECORD-1 study

INTRODUCTION

In the phase III RECORD-1 trial (ClinicalTrials.gov: NCT00410124), patients with metastatic renal cell carcinoma (mRCC) who progressed on previous vascular endothelial growth factor receptor-tyrosine kinase inhibitor (VEGFr-TKI) therapy were randomised 2:1 to everolimus 10mg once daily (n=277) or placebo (n=139). Median progression-free survival (PFS) was 4.9months with everolimus and 1.9months with placebo (hazard ratio [HR], 0.33; P<.001). This preplanned, prospective sub-analysis evaluated PFS benefit of everolimus versus placebo in patients who had previously received 1 or 2 VEGFr-TKIs.

PATIENTS AND METHODS

Median PFS was estimated using the Kaplan-Meier method, and Cox proportional hazards model was used to analyse differences in PFS.

RESULTS

All patients (100%) received ⩾1 previous VEGFr-TKI; 26% of patients received 2 previous VEGFr-TKIs. Among patients who received 1 previous VEGFr-TKI, median PFS was 5.4months with everolimus and 1.9months with placebo (HR, 0.32; 95%confidence interval [CI], 0.24-0.43; P<.001). Among patients who received 2 previous VEGFr-TKIs, median PFS was 4.0months with everolimus and 1.8months with placebo (HR, 0.32; 95%CI, 0.19-0.54; P<.001). The everolimus safety profile was similar for both groups.

CONCLUSIONS

Everolimus was associated with prolonged PFS relative to placebo in patients who received 1 or 2 previous VEGFr-TKIs. Patients who received only 1 previous VEGFr-TKI had apparently longer PFS with everolimus in reference to those who received 2 previous VEGFr-TKIs. These results support the use of everolimus as the standard of care in patients who fail initial VEGFr-TKI therapy.

The risk of skin rash and stomatitis with the mammalian target of rapamycin inhibitor temsirolimus: a systematic review of the literature and meta-analysis

OBJECTIVE

We conducted a systematic review of the literature and performed a meta-analysis to determine the risk of developing skin rash and stomatitis among patients receiving temsirolimus.

METHODS

Databases from PubMed and Web of Science from January, 1998 until June, 2011 and abstracts presented at the American Society of Clinical Oncology annual meetings from 2004 through 2011 were searched to identify relevant studies. The incidence and relative risk (RR) of skin rash and stomatitis were calculated using random-effects or fixed-effects model depending on the heterogeneity of included studies.

RESULTS

A total of 779 patients from 10 clinical trials were included in this analysis. The overall incidence of all-grade rash was 45.8% (95% confidence interval (CI): 35.6-56.3%), with a RR of 7.6 (95%CI: 4.4-13.3; p<0.001). The overall incidence of high-grade rash was 3.3% (95%CI: 1.9-5.6%), with a RR of 13.70 (95%CI: 0.82-227.50, p=0.07). The overall incidence of all-grade stomatitis was 44.3% (CI: 32.1-57.1%), with a RR of 11.10, 95%CI: 5.60-22.00; p<0.001). The overall incidence of high-grade stomatitis was 3.2% (95%CI: 1.9-5.4%), with a RR of 13.2 (95%CI: 0.80-218.50, p=0.07).

CONCLUSION

There is a significant risk of developing skin rash and stomatitis in cancer patients receiving temsirolimus. The risk is independent of underlying tumour. Adequate monitoring and early intervention are recommended to prevent debilitating toxicity and suboptimal dosing.

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.

DNA-PK mediates AKT activation and apoptosis inhibition in clinically acquired platinum resistance

Clinical resistance to chemotherapy is a frequent event in cancer treatment and is closely linked to poor outcome. High-grade serous (HGS) ovarian cancer is characterized by p53 mutation and high levels of genomic instability. Treatment includes platinum-based chemotherapy and initial response rates are high; however, resistance is frequently acquired, at which point treatment options are largely palliative. Recent data indicate that platinum-resistant clones exist within the sensitive primary tumor at presentation, implying resistant cell selection after treatment with platinum chemotherapy. The AKT pathway is central to cell survival and has been implicated in platinum resistance. Here, we show that platinum exposure induces an AKT-dependent, prosurvival, DNA damage response in clinically platinum-resistant but not platinum-sensitive cells. AKT relocates to the nucleus of resistant cells where it is phosphorylated specifically on S473 by DNA-dependent protein kinase (DNA-PK), and this activation inhibits cisplatin-mediated apoptosis. Inhibition of DNA-PK or AKT, but not mTORC2, restores platinum sensitivity in a panel of clinically resistant HGS ovarian cancer cell lines: we also demonstrate these effects in other tumor types. Resensitization is associated with prevention of AKT-mediated BAD phosphorylation. Strikingly, in patient-matched sensitive cells, we do not see enhanced apoptosis on combining cisplatin with AKT or DNA-PK inhibition. Insulin-mediated activation of AKT is unaffected by DNA-PK inhibitor treatment, suggesting that this effect is restricted to DNA damage-mediated activation of AKT and that, clinically, DNA-PK inhibition might prevent platinum-induced AKT activation without interfering with normal glucose homeostasis, an unwanted toxicity of direct AKT inhibitors.

Temsirolimus, an mTOR inhibitor, in combination with lower-dose clofarabine as salvage therapy for older patients with acute myeloid leukaemia: results of a phase II GIMEMA study (AML-1107)

The mammalian target of rapamycin (mTOR) signalling pathway has emerged as an important therapeutic target for acute myeloid leukaemia (AML). This study assessed the combination of temsirolimus, an mTOR inhibitor, and lower-dose clofarabine as salvage therapy in older patients with AML. Induction consisted of clofarabine 20mg/m(2) on days 1-5 and temsirolimus 25mg (flat dose) on days 1, 8 and 15. Patients achieving complete remission with (CR) or without (CRi) full haematological recovery could receive monthly temsirolimus maintenance. In 53 evaluable patients, the overall remission rate (ORR) was 21% (8% CR, 13% CRi). Median disease-free survival was 3·5months, and median overall survival was 4months (9·1months for responders). The most common non-haematological severe adverse events included infection (48%), febrile neutropenia (34%) and transaminitis (11%). The 30-d all-cause induction mortality was 13%. Laboratory data from 25 patients demonstrated that a >50%in vivo inhibition of S6 ribosomal protein phosphorylation was highly correlated with response rate (75% with inhibition versus 0% without inhibition; P=0·0001), suggesting that targeting the mTOR pathway is clinically relevant. The acceptable safety profile and the predictive value of target inhibition encourage further investigation of this novel regimen.

Targeted therapy in renal cancer

Renal cell cancer (RCC) has an increasing incidence internationally and is a disease for which there have been limited therapeutic options until recently. The last decade has seen a vastly improved understanding of the biological and clinical factors that predict the outcome of this disease. We now understand some of the different molecular underpinnings of renal clear cell carcinoma by mutation or silencing of the von Hippel Lindau (VHL) gene and subsequent deregulated proliferation and angiogenesis. Survival in advanced disease is predicted by factors (performance status, anemia, hypercalcemia, and serum lactate dehydrogenase, time from diagnosis to recurrence) incorporated into the Memorial Sloan Kettering Cancer Center (MSKCC) criteria (also referred to as 'Motzer' criteria). These criteria allow classification of patients with RCC into good, intermediate and poor risk categories with median overall survivals of 22 months, 12 months and 5.4 months, respectively. Predicated upon these advances, six new targeted drugs (sorafenib, sunitinib, temsirolimus, everolimus, bevacizumab and pazopanib) have been tested in well-designed phase III trials, selected or stratified for MSKCC risk criteria, with positive results. All of these new drugs act at least in part through vascular endothelial growth factor (VEGF) mediated pathways with other potential therapeutic impact on platelet-derived growth factor (PDGF), raf kinase and mammalian target of rapamycin (mTOR) pathways. Importantly, data from each of these trials show a consistent doubling of progression-free survival (PFS) over prior standard of care treatments. In addition, sorafenib, sunitinib and temsirolimus, have demonstrated significant overall survival (OS) benefits as well; further follow-up is required to determine whether the disease control exhibited by everolimus and pazopanib will translate into a survival advantage. These drugs are generally well tolerated, as demonstrated by quality-of-life improvement in clinical trials, and result in clinical benefit for in excess of 70% of patients treated. They have challenged the traditional outcomes of clinical trial design by achieving their benefits with relatively few radiographic responses, but high rates of disease stability. The unique side-effect profile coupled with the chronicity of therapy requires increased vigilance to maximize exposure to the drugs while maintaining quality of life and minimizing toxicity. This review focuses on the background, clinical development and practical use of these new drugs in RCC.

Sequencing of agents for metastatic renal cell carcinoma: can we customize therapy?

CONTEXT

The expanding armamentarium of agents for the therapy of advanced clear cell renal cell carcinoma (RCC) warrants further investigation of optimal patient selection.

OBJECTIVE

To analyze the second and subsequent line of targeted therapies for advanced RCC while integrating clinical and molecular markers and imaging.

EVIDENCE ACQUISITION

Data were acquired from research published in peer-reviewed literature or presented at major conferences.

EVIDENCE SYNTHESIS

Following first-line vascular endothelial growth factor (VEGF) inhibitors, second-line therapy with everolimus, a mammalian target of rapamycin inhibitor, and axitinib, a VEGF receptor tyrosine kinase inhibitor, have demonstrated benefits in progression-free survival (PFS). Sorafenib, pazopanib, and axitinib have demonstrated extension of PFS following cytokines. Optimal patient selection based on biomarkers is undergoing investigation. Clinical trials evaluating novel agents and combinations should be preferred.

CONCLUSIONS

Currently, the sequence of therapy is based on patient and physician decision, which may be influenced by comorbidities and toxicity profiles.

How to select targeted therapy in renal cell cancer

Treatment of renal cell carcinoma has dramatically changed in the past 5 years, with the approval of six new drugs since 2006. Although treatment algorithms have been reported and updated every year since 2006, the choice of targeted therapy is not always easy. Selecting a targeted agent in metastatic renal cell carcinoma should take into account various parameters, including the status of the disease, the histology, the status of the patient and finally the availability of the drugs in each country. In addition, in front of every patient, the physician will need to raise important questions such as whether the patient should be treated, should receive surgery and also what is his prognosis. The different options are described here.

Targeting the PI3K/Akt/mTOR pathway in hepatocellular carcinoma

Despite recent advances in the understanding of the biologic basis of hepatocellular carcinoma (HCC) development, the clinical management of the disease remains a major challenge. Deregulation of the PI3K/Akt/mTOR pathway, which is a prototypic survival pathway, is increasingly implicated in HCC carcinogenesis. In this article, we detailed the role of this pathway in the pathogenesis of HCC and provide an update on the preclinical and clinical development of various agents targeting this key survival/proliferation pathway, which include various PI3K inhibitors, Akt inhibitors and mTOR inhibitors for HCC. In addition, we highlighted the therapeutic potential of combination strategy for mTOR inhibitors with conventional chemotherapy, in particular, antimicrotubule agents, other molecular targeting agents, as well as radiotherapy.

Phase II trial of the mTOR inhibitor, temsirolimus and evaluation of circulating tumor cells and tumor biomarkers in persistent and recurrent epithelial ovarian and primary peritoneal malignancies: a Gynecologic Oncology Group study

OBJECTIVE

Patients with persistent/recurrent epithelial ovarian cancer/primary peritoneal cancer (EOC/PPC) have limited treatment options. AKT and PI3K pathway activation is common in EOC/PPC, resulting in constitutive activation of downstream mTOR. The GOG conducted a phase II evaluation of efficacy and safety for the mTOR inhibitor, temsirolimus in EOC/PPC and explored circulating tumor cells (CTC) and AKT/mTOR/downstream tumor markers.

METHODS

Eligible women with measurable, persistent/recurrent EOC/PPC who had received 1-3 prior regimens were treated with 25mg weekly IV temsirolimus until progression or intolerable toxicity. Primary endpoints were progression-free survival (PFS) ≥6-months, tumor response, and toxicity. CellSearch® system was used to examine CTC, and AKT/mTOR/downstream markers were evaluated by archival tumor immunohistochemistry. Kendall's tau-b correlation coefficient (r) and Cox regression modeling were used to explore marker associations with baseline characteristics and outcome.

RESULTS

Sixty patients were enrolled in a two-stage sequential design. Of 54 eligible and evaluable patients, 24.1% (90% CI 14.9%-38.6%) had PFS ≥6 months (median 3.1 months), 9.3% (90% CI 3.7%-23.4%) experienced a partial response. Grade 3/4 adverse events included metabolic (8), gastrointestinal (8), pain (6), constitutional (5) and pulmonary (4). Suggested associations were between cyclin D1 and PFS ≥6 months, PFS or survival; positive CTC pre-treatment and lack of response; and high CTC expression of M30 and PFS ≥6 months/longer PFS.

CONCLUSIONS

Temsirolimus appears to have modest activity in persistent/recurrent EOC/PPC; however, PFS is just below that required to warrant inclusion in phase III studies in unselected patients. Cyclin D1 as a selection marker and CTC measures merit further study.

Inhibition of Akt (ser473) phosphorylation and rapamycin-resistant cell growth by knockdown of mammalian target of rapamycin with small interfering RNA in vascular endothelial growth factor receptor-1-targeting vector

Previously we developed dicetyl phosphate-tetraethylenepentamine-based polycation liposomes (TEPA-PCL) for use in small interfering RNA (siRNA) therapy. In the present study, mammalian target of rapamycin (mTOR) expression in cancer cells was silenced with mTOR-siRNA (simTOR) formulated in TEPA-PCL modified with Ala-Pro-Arg-Pro-Gly (APRPG), a peptide having affinity for vascular endothelial growth factor receptor-1 (VEGFR-1). We investigated the effects of inhibition of mTOR, focusing on the differences between cells treated with simTOR and those with rapamycin in terms of Akt (ser473) phosphorylation and antiproliferative effects. Rapamycin treatment is known to induce Akt (ser473) phosphorylation which attenuates the antiproliferative effects of rapamycin. As a result, knockdown of mTOR did not alter or only slightly reduced Akt (ser473) phosphorylation in phosphatase and tensin homolog deleted from chromosome 10 (PTEN)-null (LNCaP and MDA-MB-468 cells) and PTEN-positive (DU 145 and MDA-MB-231) cells, although rapamycin induced Akt (ser473) phosphorylation of these cells. Rapamycin suppressed the growth of PTEN-null cells, in which the rapamycin-sensitive mTOR complex 1 (mTORC1) is excessively activated. On the other hand, rapamycin did not suppress the growth of PTEN-positive cells possibly through a negative feedback mechanism via the rapamycin-insensitive mTOR complex 2 (mTORC2) signaling pathway. In contrast, simTOR significantly suppressed the growth of cancer cells regardless of the presence of PTEN, possibly through inhibition of both mTORC1 and mTORC2. These results indicate that mTOR knockdown using APRPG-TEPA-PCL/simTOR is likely to be an effective strategy for cancer siRNA therapy.

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.

Small-molecule inhibitors of the PI3K signaling network

The phosphoinositide 3-kinase (PI3K) signaling pathway controls a wide variety of cellular processes including cell death and survival, cell migration, protein synthesis and metabolism. Aberrant PI3K-dependent signaling, mediated by Akt kinase, has been implicated in many human diseases including cancer, inflammation, cardiovascular disease and metabolic diseases, making this pathway a principle target for drug development. In this article we will summarize the PI3K signaling network and discuss current strategies for pathway inhibition. We will also explore the importance and emerging relevance of Akt-independent PI3K signaling pathways and discuss attempts being made to harness these pathways by inhibiting the binding of a product of PI3K, phosphatidylinositol-(3,4,5)-trisphosphate, to effector pleckstrin homology domains.

Future directions in renal cell carcinoma: 2011 and beyond

Emerging from a largely cytokine-based era, the last several years have witnessed a dramatic change in the therapeutic landscape of renal cancer. Molecularly targeted and antiangiogenic agents now form the backbone of most therapeutic strategies for patients with advanced renal cell carcinoma (RCC). Although the next few years may not see such broad paradigm shifts, there remains significant room for improvement in the care of patients with RCC. This review discusses challenges that face physicians and researchers as well as innovations that may contribute to improving the therapeutic outcomes for patients with RCC.

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.

Fighting neurodegeneration with rapamycin: mechanistic insights

A growing number of studies point to rapamycin as a pharmacological compound that is able to provide neuroprotection in several experimental models of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease and spinocerebellar ataxia type 3. In addition, rapamycin exerts strong anti-ageing effects in several species, including mammals. By inhibiting the activity of mammalian target of rapamycin (mTOR), rapamycin influences a variety of essential cellular processes, such as cell growth and proliferation, protein synthesis and autophagy. Here, we review the molecular mechanisms underlying the neuroprotective effects of rapamycin and discuss the therapeutic potential of this compound for neurodegenerative diseases.