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

The rapamycin analog Everolimus reversibly impairs male germ cell differentiation and fertility in the mouse†

Sirolimus, also known as rapamycin, and its closely related rapamycin analog (rapalog) Everolimus inhibit "mammalian target of rapamycin complex 1" (mTORC1), whose activity is required for spermatogenesis. Everolimus is Food and Drug Administration approved for treating human patients to slow growth of aggressive cancers and preventing organ transplant rejection. Here, we test the hypothesis that rapalog inhibition of mTORC1 activity has a negative, but reversible, impact upon spermatogenesis. Juvenile (P20) or adult (P>60) mice received daily injections of sirolimus or Everolimus for 30 days, and tissues were examined at completion of treatment or following a recovery period. Rapalog treatments reduced body and testis weights, testis weight/body weight ratios, cauda epididymal sperm counts, and seminal vesicle weights in animals of both ages. Following rapalog treatment, numbers of differentiating spermatogonia were reduced, with concomitant increases in the ratio of undifferentiated spermatogonia to total number of remaining germ cells. To determine if even low doses of Everolimus can inhibit spermatogenesis, an additional group of adult mice received a dose of Everolimus ∼6-fold lower than a human clinical dose used to treat cancer. In these animals, only testis weights, testis weight/body weight ratios, and tubule diameters were reduced. Return to control values following a recovery period was variable for each of the measured parameters and was duration and dose dependent. Together, these data indicate rapalogs exerted a dose-dependent restriction on overall growth of juvenile and adult mice and negative impact upon spermatogenesis that were largely reversed; following treatment cessation, males from all treatment groups were able to sire offspring.

Significance of tumor microenvironment in acquiring resistance to vascular endothelial growth factor-tyrosine kinase inhibitor and recent advance of systemic treatment of clear cell renal cell carcinoma

The development of systemic therapies, including vascular endothelial growth factor-tyrosine kinase inhibitors (VEGF-TKI) and mammalian target of rapamycin (mTOR) inhibitors, represents a major breakthrough in the treatment of patients with renal cell carcinoma (RCC). However, inherent resistance is observed in some patients and acquired resistance commonly develops in many patients within several months of the initiation of systemic therapies. Since these treatments rarely cure patients, their aim is to suppress tumor progression and prolong survival. Therefore, the establishment of dependable criteria that predict responses and resistance to systemic therapies is clinically important, and the underlying molecular mechanisms also need to be elucidated for the future development of more effective therapies. We herein review recent advances in research on the molecular mechanisms underlying resistance, with a focus on morphological characteristics, tumor angiogenesis, and the tumor immune microenvironment in RCC and their relationships with VEGF-TKI treatments. Recent therapies using immune checkpoint inhibitors (ICI) and newly developed VEGF-TKI also appear to be effective for advanced RCC, with stable and durable responses to ICI being observed in some RCC patients. These new drugs and their outcomes have been briefly described.

mTOR and mTOR phosphorylation status in primary and metastatic renal cell carcinoma tissue: differential expression and clinical relevance

PURPOSE

Impaired regulation of the Akt/mammalian target of rapamycin (mTOR) pathway has been implicated in mechanisms related to neoplastic transformation in renal cell cancer (RCC) through enhancement of cell proliferation and survival and mTOR activation has been reported to occur due to phosphorylation of mTOR. To further determine the relevance of mTOR expression and activation and to analyze their putative role as a biomarker for systemic treatment in metastatic RCC, we investigated the expression of mTOR and phospho(p)-mTOR in primary RCC and metastases and correlated levels with pathological variables and clinical outcome.

METHODS

Tissue microarrays (TMA) from paraffin-embedded tissue from 342 patients with primary clear cell renal cell carcinoma and 90 patients undergoing surgical resection for metastases were immunohistochemically stained for mTOR and p-mTOR and expression was quantified with immunoreactivity scores. Clinical patient characteristics and follow-up were recorded. Comparative evaluation of protein expression levels and association of expression with clinical variables and survival was performed.

RESULTS

mTOR staining revealed differential expression in benign, primary and RCC metastasis (average staining score: 1.64, 0.78, and 1.44, respectively). Average staining of p-mTOR was 0.99 in benign kidney tissue, 0.73 in primary RCC and 1.14 in RCC metastasis tissue. Elevated mTOR expression in primary RCC tissue was associated with the presence of tumor necrosis, while a high level of p-mTOR was significantly correlated with advanced T-stage, high Fuhrman grade, the presence of tumor necrosis and sarcomatoid features. An elevated ratio of p-mTOR/mTOR was significantly correlated with advanced stage and sarcomatoid histology. mTOR expression was not predictive of overall survival (OS), while high p-mTOR levels were associated with impaired OS (p = 0.0046) and cancer-specific survival (p = 0.0067). In univariate analysis, advanced stage (HR 3.78), high Fuhrman grade (HR 4.0), the presence of tumor necrosis (HR 1.99), and sarcomatoid features (HR 5.12) were significant predictors of OS. Moreover, elevated levels of p-mTOR (HR 1.67) and an elevated ratio of p-mTOR/mTOR ratio (HR 1.73) were significantly predictive of OS. In the multivariate regression model only the presence of locally advanced tumors (HR 2.44) was of independent prognostic value for OS, while there was a trend for impaired OS for patients with a high p-mTOR (HR 1.27, p = 0.21).

CONCLUSIONS

Phosphorylated mTOR is differentially expressed in localized RCC and metastasis. Elevated phosphorylation of mTOR is associated with aggressive pathologic features and unfavorable outcome. Whether these findings portend to relevance for mTOR inhibition treatment for metastatic RCC should be objective of further investigations.

Efficacy and safety of everolimus treatment in a hemodialysis patient with metastatic atypical bronchial carcinoid: case report and literature review

Background

Everolimus was recently approved for the treatment of neuroendocrine tumors. However, its efficacy and tolerability in hemodialysis patients with end-stage renal disease is not established.

Case presentation

We describe the case of a 47-year-old man with end-stage renal disease who received everolimus plus Lanreotide for 9 months for the management of metastatic atypical bronchial carcinoid.

Conclusions

Everolimus is a treatment option for hemodialysis patients with metastatic atypical bronchial carcinoid. Based on our case report and review of literature, Everolimus does not require any dose reductions and is overall well tolerated in hemodialysis patients.

Risk of hyperglycemia attributable to everolimus in cancer patients: A meta-analysis

Everolimus has been used widely in cancer patients and is associated with the development of hyperglycemia. Due to confounding factors, its specific impact on hyperglycemia has not been well understood. We performed a meta-analysis of randomized controlled trials to determine the risk of hyperglycemia attributable to everolimus in cancer patients of varying tumor types.

MATERIAL AND METHODS

PubMed and American Society of Clinical Oncology conference abstracts up to June 2015 were systematically searched. Eligible studies included randomized controlled trials (RCTs) in which everolimus was compared to placebo in cancer patients with or without other agents. Heterogeneity tests were performed to examine between-study differences in hyperglycemia, and the incidence and relative risk of all- and high-grade hyperglycemia attributable to everolimus were determined using both random- or fixed-effects models.

RESULTS

A total of seven phase III and two phase II RCTs with various tumors, encompassing a total of 3879 cancer patients, were included in our analysis. Everolimus significantly increased the risk of all-grade (RR =2.60, 95% CI 2.03-3.31, p < 0.001) and high-grade (RR =3.0, 95% CI 1.72-5.23; p < 0.001) hyperglycemia. The incidences of all- and high-grade hyperglycemia attributable to everolimus were 6.8% (95% CI 3.4-13.2%) and 2.5% (95% CI 1.2-4.9%), respectively. The everolimus-specific risk of all-grade hyperglycemia varied significantly with tumor types (p < 0.001), with the highest incidence seen in renal cell carcinoma (RCC) (27.2%, 95% CI 22.2-32.8%) and the lowest in breast cancer (3.3%, 95% CI 1.3-8.2%). No significant variation was found between everolimus alone or everolimus in combination with other agents. Similar results were also found for the risk of high-grade hyperglycemia attributable to everolimus.

CONCLUSION

The specific risk of hyperglycemia attributable to everolimus may vary significantly with tumor types. Close monitoring should be given to patients at high risk, such as RCC.

Safe handling of oral antineoplastic medications: Focus on targeted therapeutics in the home setting

Introduction With the growing number of oral targeted therapies being approved for use in cancer therapy, the potential for long-term administration of these drugs to cancer patients is expanding. The use of these drugs in the home setting has the potential to expose family members and caregivers to them either through direct contact with the drugs or indirectly by exposure to the parent compounds and/or their active metabolites in contaminated patients' waste. Methods A systematic literature review was performed and the known adverse health effect of 32 oral targeted therapeutics is summarized. In particular, the carcinogenicity, genotoxicity, and embryo-fetal toxicity, along with the route of excretion were evaluated. Results Carcinogenicity testing has not been performed on most of the oral targeted therapeutics and the genotoxicity data are mixed. However, the majority of these drugs exhibit adverse reproductive effects, some of which are severe. Currently, available data does not permit the possibility of a health hazard from inappropriate handling of drugs and contaminated patients waste to be ignored, especially in a long-term home setting. Further research is needed to understand these issues. Conclusions With the expanding use of targeted therapies in the home setting, family members and caregivers, especially those of reproductive risk age, are, potentially at risk. Overall basic education and related precautions should be taken to protect family members and caregivers from indirect or direct exposure from these drugs. Further investigations and discussion on this subject are warranted.

Metformin reverses multidrug resistance in human hepatocellular carcinoma Bel‑7402/5‑fluorouracil cells

Metformin exhibits anti‑proliferative effects in tumor cells in vitro and in vivo. The present study investigated the ability of metformin to reverse multidrug resistance (MDR) in human hepatocellular carcinoma Bel‑7402/5‑fluorouracil (5‑Fu; Bel/Fu) cells. The synergistic anti‑proliferative effect of metformin combined with 5‑Fu was evaluated using a Cell Counting kit‑8 assay. The variation in apoptotic rates and cell cycle distribution were evaluated using a flow cytometric assay and variations in target gene and protein expression were monitored using reverse transcription‑polymerase chain reaction and western blot analysis. The results demonstrated that metformin had a synergistic anti‑proliferative effect with 5‑Fu in the Bel/Fu cells. The variations in the number of apoptotic cells and distribution of the cell cycle were consistent with the variability in cell viability. Metformin targeted the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway, suppressed the expression of hypoxia‑inducible factor‑1α (HIF‑1α) and transcriptionally downregulated the expression of multidrug resistance protein 1/P‑glycoprotein (P‑gp) and multidrug resistance‑associated protein 1 (MRP1). Collectively, these findings suggested that metformin may target the AMPK/mTOR/HIF‑1α/P‑gp and MRP1 pathways to reverse MDR in hepatocellular carcinoma.

Outcomes of patients with metastatic renal cell carcinoma and end-stage renal disease receiving dialysis and targeted therapies: a single institution experience

INTRODUCTION

Limited data are available regarding patients with renal cell carcinoma and ESRD treated with TTs. The objective of this study was to explore the tolerability and safety of TT in patients with mRCC and ESRD.

PATIENTS AND METHODS

We retrospectively identified patients with mRCC and ESRD treated at the University of Texas M.D. Anderson Cancer Center from 2002 to 2012. Patient characteristics including demographic, histology, treatment, and adverse events are reported. Duration of treatment (TOT) was determined from date of drug initiation to discontinuation. Overall survival (OS) was determined from initiation of TT to death. Statistics are descriptive.

RESULTS

Fourteen patients were identified. Ten patients had clear-cell histology and 4 had papillary histology. The median number of TTs per patient was 3 (range, 1-4) with median TOT of 28 months for all TTs. Eighty-eight percent of all toxicities were Grade 1 to 2; no Grade 4 toxicities were noted. Treatment discontinuations included 3 patients treated with sorafenib due to hand-foot syndrome, intolerable fatigue, and squamous cell skin cancer development; 2 patients treated with pazopanib due to intolerable fatigue and increased transaminase levels; and 1 patient treated with everolimus due to pneumonitis. Eight patients died from progressive disease. Median OS from initiation of TT was 28.5 months and 35 months from time of diagnosis.

CONCLUSION

Toxicities were mild to moderate and consistent with those reported in previous studies. TTs appear to be safe, well tolerated and produce antitumor response in patients with mRCC and ESRD receiving dialysis.

Everolimus: a new treatment option for advanced pancreatic neuroendocrine tumors

OBJECTIVE

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

DATA SOURCES

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

STUDY SELECTION AND DATA EXTRACTION

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

DATA SYNTHESIS

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

CONCLUSIONS

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

3rd Pavia international symposium on advanced kidney cancer

Kidney cancers' natural history has radically changed in the past few years, due to the development of novel targeted agents. Despite these improvements, several unanswered questions still remain on the table, regarding the best first-line treatment, the ideal sequence of treatments, the management of specific subgroups of patients (e.g., elderly patients or those with comorbidities) and the relevance of prognostic factors, among many others. To foster discussions among clinicians and investigators working in this field, and to exchange different viewpoints concerning the newest advances in kidney cancer pathogenesis and treatment, the 3rd Pavia International Symposium on Advanced Kidney cancer was held in Pavia (Italy) between 30 June and 1 July 2011. The aim of this report is to summarize the most significant advances in the different disciplines applied to advanced kidney cancer, which were presented and discussed during the meeting, and how these advances will be changing the perspective of patients with this disease.