Everolimus: an update on the mechanism of action, pharmacokinetics and recent clinical trials

A Narrative Review of Chromatographic Bioanalytical Methods for Quantifying Everolimus in Therapeutic Drug Monitoring Applications

BACKGROUND

Methods for measuring drug levels in the body are crucial for improving therapeutic drug monitoring (TDM) and personalized medicine. In solid-organ transplants, TDM is essential for the management of immunosuppressive drugs to avoid toxicity and organ rejection. Everolimus is a commonly used immunosuppressant with a small range of safe doses; therefore, it is important to adjust the dose according to each patient's needs. Therefore, reliable methods are required to accurately measure everolimus levels. This study aims to conduct a comprehensive and updated narrative review of chromatographic bioanalytical methods for everolimus quantification.

METHODS

The authors searched for original research articles published between 2013 and 2023 in Scopus and PubMed and found 295 articles after removing duplicates. Based on their titles and summaries, 30 articles were selected for a detailed review and 25 articles were included in the final analysis.

RESULTS

Among the 25 studies, 16 used protein precipitation, mainly with methanol, to prepare the samples, 12 used high-performance liquid chromatography, 11 used ultra-performance liquid chromatography, and 2 used both. Almost all the studies (24 of 25) used tandem mass spectrometry for detection, whereas only 1 used ultraviolet.

CONCLUSIONS

This comprehensive review of bioanalytical methods for measuring everolimus using chromatography is a useful resource for researchers developing bioanalytical methods for TDM applications. Future trends in everolimus measurement include achieving lower detection limits, owing to the trend of reducing drug doses in therapy by improving sample extraction techniques and using more sensitive methods.

Dosing-time, feeding, and sex-dependent variations of everolimus pharmacokinetics in mice

BACKGROUND

Everolimus is an oral mammalian target of rapamycin (mTOR) inhibitor used as an immunosuppressant and anticancer. Its pharmacokinetics is highly variable, it has a narrow therapeutic window and shows chronotoxicity with the best time at ZT13 and worst time at ZT1 (ZT; Zeitgeber time, time after light onset) in the preclinical setting.

OBJECTIVES

In the present study, we aimed to investigate whether the pharmacokinetics of everolimus vary according to dosing time and whether sex and feeding status interfere with the chronopharmacokinetics.

METHOD

A single dosage of 5 mg/kg everolimus was administered orally to C57BL/6J male and female mice, in fed or fasted states at ZT1-rest and ZT13-activity times and blood and tissue samples were collected at 0.5, 1, 2, 4, 12, and 24 h following drug administration. Ileum, liver, plasma, and thymus concentrations of everolimus were determined.

RESULTS

Females had a greater ileum AUC0-24h than males when fed (P = 0.043). Everolimus AUC0-24h in the liver was substantially greater at ZT1 than at ZT13 in a fasted state (P = 0.001). Plasma Cmax, AUC0-24h, and AUCtotal were not statistically significant between the groups (P = 0.098). In one of the target organs of everolimus, the thymus, males had considerably higher amounts at ZT1 than females (P = 0.029).

CONCLUSION

Our findings imply that the pharmacokinetics of everolimus in mice may differ according to dosing time, sex, and feeding. Greater tissue distribution of everolimus at ZT1 may be associated with the worst tolerated time of everolimus. Our research suggests that oral chronomodulated everolimus therapy may be more effective and safer for cancer patients.

Aggressive pituitary tumors and carcinomas: medical treatment beyond temozolomide

Aggressive pituitary tumors are a subset of pituitary neoplasms, characterized by unusually fast growth rate, invasiveness and overall resistance to optimized standard treatment. When metastases are present, the term pituitary carcinoma is employed. After failure of standard treatments, current guidelines recommend first-line temozolomide monotherapy. However, a significant number of patients do not respond to temozolomide, or experience disease progression following its discontinuation; in these latter cases, re-challenge with temozolomide is generally advised, although the reported outcomes have been less satisfactory. Although no alternative therapies have been formally recommended after temozolomide failure, growing evidence regarding potential second- or third-line therapeutic strategies has emerged. In the present work, we reviewed the available evidence published up to April 2023 involving the most relevant therapies employed so far, namely immune checkpoint inhibitors, bevacizumab, peptide radionuclide receptor therapy, tyrosine kinase inhibitors and mTOR inhibitors. For each treatment, we report efficacy and safety outcomes, along with data regarding potential predictors of response. Overall, immune checkpoint inhibitors and bevacizumab are showing the most promise as therapeutic options after temozolomide failure. The former showed better responses in pituitary carcinomas. Peptide radionuclide receptor therapy has also showed some efficacy in these tumors, while tyrosine kinase inhibitors and mTOR inhibitors have exhibited so far limited or no efficacy. Further studies, as well as an individualized, patient-tailored approach, are clearly needed. In addition, we report an unpublished case of a silent corticotroph pituitary carcinoma that progressed under dual immunotherapy, and then showed stable disease under a combination of lomustine and bevacizumab.

Preclinical Evaluation of an Everolimus-Eluting Bioresorbable Vascular Scaffold Via a Long-Term Rabbit Iliac Artery Model

BACKGROUND

Biodegradable poly (l-lactic acid) (PLLA), a bio safe polymer with a large elastic modulus, is widely used in biodegradable medical devices. However, because of its poor mechanical properties, a PLLA strut must be made twice as thick as a metal strut for adequate blood vessel support. Therefore, the mechanical properties of a drug-eluting metal-based stents (MBS) and a bioresorbable vascular scaffolds (BVS) were evaluated and their safety and efficacy were examined via a long-term rabbit iliac artery model.

METHODS

The surface morphologies of the MBSs and BVSs were investigated via optical and scanning electron microscopy. An everolimus-eluting (EE) BVS or an EE-MBS was implanted into rabbit iliac arteries at a 1.1:1 stent-to-artery ratio. Twelve months afterward, stented iliac arteries from each group were analyzed via X-ray angiography, optical coherence tomography (OCT), and histopathologic evaluation.

RESULTS

Surface morphology analysis of the EE coating on the MBS confirmed that it was uniform and very thin (4.7 μm). Comparison of the mechanical properties of the EE-MBS and EE-BVS showed that the latter outperformed the former in all aspects (radial force (2.75 vs. 0.162 N/mm), foreshortening (0.24% vs. 1.9%), flexibility (0.52 vs. 0.19 N), and recoil (3.2% vs. 6.3%). At all time points, the percent area restenosis was increased in the EE-BVS group compared to the EE-MBS group. The OCT and histopathological analyses indicate no significant changes in strut thickness.

CONCLUSION

BVSs with thinner struts and shorter resorption times should be developed. A comparable long-term safety/efficacy evaluation after complete absorption of BVSs should be conducted.

Everolimus for the treatment of epithelioid hemangioma: a case report

Epithelioid hemangioma is a rare benign vascular tumor manifested as slow-growing subcutaneous or dermal nodules. A previously therapeutic strategy involved surgical excision and sclerotherapy. However, no standard treatment has been established. Here, we reported an atypical case of epithelioid hemangioma that had a locally aggressive behavior and was successfully treated with everolimus, a rapamycin analog used for cancer therapy. A 1-year-old boy presented with an ulcerated lump in the left palmar region. The imaging test results, confirmed through histopathologic examination, suggested a diagnosis of epithelioid hemangioma. Targeted therapy with everolimus was administered orally because of a minimal response to initial transarterial sclerotherapy. The patient achieved a satisfactory response with a significantly reduced lesion size and improved hand function after a 2-year follow-up. This finding showed that patients with locally aggressive forms of epithelioid hemangioma may significantly benefit from everolimus as a potential targeted therapy.

Autofluorescence Imaging of Treatment Response in Neuroendocrine Tumor Organoids

Gastroenteropancreatic neuroendocrine tumors (GEP-NET) account for roughly 60% of all neuroendocrine tumors. Low/intermediate grade human GEP-NETs have relatively low proliferation rates that animal models and cell lines fail to recapitulate. Short-term patient-derived cancer organoids (PDCOs) are a 3D model system that holds great promise for recapitulating well-differentiated human GEP-NETs. However, traditional measurements of drug response (i.e., growth, proliferation) are not effective in GEP-NET PDCOs due to the small volume of tissue and low proliferation rates that are characteristic of the disease. Here, we test a label-free, non-destructive optical metabolic imaging (OMI) method to measure drug response in live GEP-NET PDCOs. OMI captures the fluorescence lifetime and intensity of endogenous metabolic cofactors NAD(P)H and FAD. OMI has previously provided accurate predictions of drug response on a single cell level in other cancer types, but this is the first study to apply OMI to GEP-NETs. OMI tested the response to novel drug combination on GEP-NET PDCOs, specifically ABT263 (navitoclax), a Bcl-2 family inhibitor, and everolimus, a standard GEP-NET treatment that inhibits mTOR. Treatment response to ABT263, everolimus, and the combination were tested in GEP-NET PDCO lines derived from seven patients, using two-photon OMI. OMI measured a response to the combination treatment in 5 PDCO lines, at 72 h post-treatment. In one of the non-responsive PDCO lines, heterogeneous response was identified with two distinct subpopulations of cell metabolism. Overall, this work shows that OMI provides single-cell metabolic measurements of drug response in PDCOs to guide drug development for GEP-NET patients.

Opportunistic and Serious Infections in Patients with Neuroendocrine Tumors Treated with Everolimus: A Multicenter Study of Real-World Patients

INTRODUCTION

The incidence of infections is poorly studied in patients with neuroendocrine tumors (NET) treated with everolimus outside of clinical trials. We aimed to evaluate the frequency of and risk factors for opportunistic infections (Opl) or any serious infection in eligible patients.

METHODS

This was a retrospective multicenter study of a Latin American cohort of consecutive patients with advanced NET treated with everolimus. Duration of everolimus, comorbidities, Charlson comorbidity score, type of prior treatment, institution, and concurrent immunosuppressive conditions were tested for possible associations with serious (grade 3-5) infections in univariate and multivariable logistic regression models.

RESULTS

One hundred eleven patients from 5 centers were included. The median duration of everolimus was 8.9 months. After a median follow-up of 32.9 months, 34 patients (30.6%; 95% CI 22.2-40.1) experienced infections of any grade, with 24 (21.6%; 95% CI 14.8-30.4) having a serious infection and 7 (6.3%; 95% CI 2.6-12.6) having at least 1 OpI (Candida sp., Toxoplasma gondi, Pneumocystis sp., Herpes sp., and Cryptococcus sp.). Four patients (3.6%) died from infections, but only 2 deaths (1.8%) were deemed to be related to everolimus. The multivariable analysis identified everolimus duration (every 6-month increase; OR = 1.28; 95% CI 1.02-1.60; p = 0.03) as an independent risk factor for serious infection.

CONCLUSION

Infections are more frequent in NET patients using everolimus than previously reported in clinical trials. Patients on everolimus should be closely monitored for infections, especially those receiving it for several months.

Dose-Dependent Acute Effects of Everolimus Administration on Immunological, Neuroendocrine and Psychological Parameters in Healthy Men

The rapamycin analogue everolimus (EVR) is a potent inhibitor of the mammalian target of rapamycin (mTOR) and clinically used to prevent allograft rejections as well as tumor growth. The pharmacokinetic and immunosuppressive efficacy of EVR have been extensively reported in patient populations and in vitro studies. However, dose-dependent ex vivo effects upon acute EVR administration in healthy volunteers are rare. Moreover, immunosuppressive drugs are associated with neuroendocrine changes and psychological disturbances. It is largely unknown so far whether and to what extend EVR affects neuroendocrine functions, mood, and anxiety in healthy individuals. Thus, in the present study, we analyzed the effects of three different clinically applied EVR doses (1.5, 2.25, and 3 mg) orally administered 4 times in a 12-hour cycle to healthy male volunteers on immunological, neuroendocrine, and psychological parameters. We observed that oral intake of medium (2.25 mg) and high doses (3 mg) of EVR efficiently suppressed T cell proliferation as well as IL-10 cytokine production in ex vivo mitogen-stimulated peripheral blood mononuclear cell. Further, acute low (1.5 mg) and medium (2.25 mg) EVR administration increased state anxiety levels accompanied by significantly elevated noradrenaline (NA) concentrations. In contrast, high-dose EVR significantly reduced plasma and saliva cortisol as well as NA levels and perceived state anxiety. Hence, these data confirm the acute immunosuppressive effects of the mTOR inhibitor EVR and provide evidence for EVR-induced alterations in neuroendocrine parameters and behavior under physiological conditions in healthy volunteers.

Circulating delta-like Notch ligand 1 is correlated with cardiac allograft vasculopathy and suppressed in heart transplant recipients on everolimus-based immunosuppression

Cardiac allograft vasculopathy (CAV) causes heart failure after heart transplantation (HTx), but its pathogenesis is incompletely understood. Notch signaling, possibly modulated by everolimus (EVR), is essential for processes involved in CAV. We hypothesized that circulating Notch ligands would be dysregulated after HTx. We studied circulating delta-like Notch ligand 1 (DLL1) and periostin (POSTN) and CAV in de novo HTx recipients (n = 70) randomized to standard or EVR-based, calcineurin inhibitor-free immunosuppression and in maintenance HTx recipients (n = 41). Compared to healthy controls, plasma DLL1 and POSTN were elevated in de novo (P < .01; P < .001) and maintenance HTx recipients (P < .001; P < .01). Use of EVR was associated with a treatment effect for DLL1. For de novo HTx recipients, a change in DLL1 correlated with a change in CAV at 1 (P = .021) and 3 years (P = .005). In vitro, activation of T cells increased DLL1 secretion, attenuated by EVR. In vitro data suggest that also endothelial cells and vascular smooth muscle cells (VSMCs) could contribute to circulating DLL1. Immunostaining of myocardial specimens showed colocalization of DLL1 with T cells, endothelial cells, and VSMCs. Our findings suggest a role of DLL1 in CAV progression, and that the beneficial effect of EVR on CAV could reflect a suppressive effect on DLL1. Trial registration numbers-SCHEDULE trial: ClinicalTrials.gov NCT01266148; NOCTET trial: ClinicalTrials.gov NCT00377962.

Everolimus, a mammalian target of rapamycin inhibitor, ameliorated streptozotocin-induced learning and memory deficits via neurochemical alterations in male rats

Everolimus (EVR), as a rapamycin analog, is a selective inhibitor of the mammalian target of rapamycin (mTOR) kinase and its associated signaling pathway. mTOR is a serine/threonine protein kinase and its hyperactivity is involved in the pathophysiology of Alzheimer's disease (AD) and associated cognitive deficits. The present study evaluated the impact of EVR, on cognitive functions, hippocampal cell loss, and neurochemical parameters in the intracerebroventricular streptozotocin (icv-STZ) model of AD rats. EVR (1 and 5 mg/kg) was administered for 21 days following the single administration of STZ (3 mg/kg, icv) or for 7 days on days 21-28 post-STZ injection after establishment of cognitive dysfunction. Cognitive deficits (passive avoidance and spatial memory), oxidative stress parameters, acetylcholinesterase (AChE) activity, and percentage of cell loss were evaluated in the hippocampus. Chronic administration (1 and 5 mg/kg for 21 days from the day of surgery and icv-STZ infusion) or acute injection (5 mg/kg for 7 days after establishment of cognitive impairment) of EVR significantly attenuated cognitive dysfunction, neuronal loss, oxidative stress and AChE activity in the hippocampus of STZ-AD rats. In conclusion, our study showed that EVR could prevent or improve deteriorations in behavioral, biochemical and histopathological features of the icv-STZ rat model of AD. Therefore, inhibition of the hyperactivated mTOR may be an important therapeutic target for AD.

Efficacy and Safety of Everolimus for Maintenance Immunosuppression of Kidney Transplantation: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Conversion to everolimus is often used in kidney transplantation to overcome calcineurin inhibitor (CNI) nephrotoxicity but there is conflicting evidence for this approach.

OBJECTIVES

To investigate the benefits and harm from randomized clinical trials (RCTs) involving the conversion from CNI to everolimus after kidney transplantation.

METHODS

Databases were searched up to March 2016. Two reviewers independently assessed trials for eligibility and quality, and extracted data. Results are expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

RESULTS

Eleven RCTs, with a total of 1,633 patients, met the final inclusion criteria. Patients converted to everolimus had improved renal function at 1 year posttransplant with an estimated glomerular filtration rate (eGFR) of 5.36 mL/min per 1.73 m2 greater than patients remaining on CNI (p = 0.0005) and the longer-term results (> 1 year) of renal function was identical to that of 1 year. There was not a substantial difference in graft loss, mortality, and the occurrence of adverse events (AEs) or serious AEs. However, the risks of acute rejection and trial termination due to AEs with everolimus are respectively 1.82 and 2.63 times greater than patients staying on CNI at 1 year posttransplant (p = 0.02, p = 0.03, respectively). Further, those patients who converted to everolimus had a substantially greater risk of anemia, hyperlipidemia, hypercholesterolemia, hypokalemia, proteinuria, stomatitis, mouth ulceration, and acne.

CONCLUSIONS

Conversion from CNI to everolimus after kidney transplantation is associated with improved renal function in the first 5 years posttransplant but increases the risk of acute rejection at 1 year posttransplant and may not be well endured.

Long-term cross-validation of everolimus therapeutic drug monitoring assays: the Zortracker study

BACKGROUND

This ongoing academic collaboration was initiated for providing support to set up, validate, and maintain everolimus therapeutic drug monitoring assays and to study long-term interlaboratory performance.

METHODS

This study was based on EDTA whole blood samples collected from transplant patients treated with everolimus in a prospective clinical trial. Samples were handled under controlled conditions during collection, storage and were shipped on dry ice to minimize freeze-thaw cycles. For more than 1.5 years, participating laboratories received a set of 3 blinded samples on a monthly basis. Among others, these samples included individual patient samples, patient sample pools to assess long-term performance, and patient samples pools enriched with isolated everolimus metabolites.

RESULTS

The results between liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and the everolimus Quantitative Microsphere System (QMS, Thermo Fisher) assay were comparable. The monthly interlaboratory variability (coefficient of variation %) for cross-validation samples ranged from 6.5% to 23.2% (average of 14.8%) for LC-MS/MS and 4.2% to 26.4% (average of 11.1%) for laboratories using the QMS assay. A blinded long-term pool sample was sent to the laboratories for 13 months. The result was 5.31 ± 0.86 ng/mL (range, 2.9-7.8 ng/mL) for the LC-MS/MS and 5.20 ± 0.54 ng/mL (range, 4.0-6.8 ng/mL) for QMS laboratories. Enrichment of patient sample pools with 5-25 ng/mL of purified everolimus metabolites (46-hydroxy everolimus and 39-O-desmethyl everolimus) did not affect the results of either LC-MS/MS or QMS assays.

CONCLUSIONS

Both LC-MS/MS and QMS assays gave similar results and showed similar performance, albeit with a trend toward higher interlaboratory variability among laboratories using LC-MS/MS than the QMS assay.

Chronic Renal Transplant Rejection and Possible Anti-Proliferative Drug Targets

The global prevalence of renal transplants is increasing with time, and renal transplantation is the only definite treatment for end-stage renal disease. We have limited the acute and late acute rejection of kidney allografts, but the long-term survival of renal tissues still remains a difficult and unanswered question as most of the renal transplants undergo failure within a decade of their transplantation. Among various histopathological changes that signify chronic allograft nephropathy (CAN), tubular atrophy, fibrous thickening of the arteries, fibrosis of the kidney interstitium, and glomerulosclerosis are the most important. Moreover, these structural changes are followed by a decline in the kidney function as well. The underlying mechanism that triggers the long-term rejection of renal transplants involves both humoral and cell-mediated immunity. T cells, with their related cytokines, cause tissue damage. In addition, CD 20+ B cells and their antibodies play an important role in the long-term graft rejection. Other risk factors that predispose a recipient to long-term graft rejection include HLA-mismatching, acute episodes of graft rejection, mismatch in donor-recipient age, and smoking. The purpose of this review article is the analyze current literature and find different anti-proliferative agents that can suppress the immune system and can thus contribute to the long-term survival of renal transplants. The findings of this review paper can be helpful in understanding the long-term survival of renal transplants and various ways to improve it.

Sirolimus for treatment of autosomal-dominant polycystic kidney disease: a meta-analysis of randomized controlled trials

BACKGROUND

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common form of cystic kidney disease. The mammalian target of rapamycin (mTOR) pathway is associated with progressive kidney enlargement. The drug sirolimus suppresses mTOR signaling but plays an uncertain role in the treatment of ADPKD. The objective of our study was to conduct a meta-analysis of randomized controlled trials (RCTs) to present an objective appraisal of the efficacy and safety of sirolimus therapy in patients with ADPKD.

METHODS

We conducted a meta-analysis of RCTs performed in adults with ADPKD, and compared the effect of sirolimus on total kidney volume (TKV), glomerular filtration rate (GFR), cyst volume, and daily urinary protein excretion. Safety was evaluated based on analysis of blood pressure, lipid profile, complete blood count, infection, and other reported adverse events.

RESULTS

Four RCTs were included. The sirolimus therapy group had smaller TKV than the control group. The mean difference (MD) of TKV post-treatment compared with the control group was -234.74 (P = .01). However, GFR did not reach a statistically significant difference between groups. Standard mean difference (SMD) of GFR after therapy was 0.24 (95% confidence interval [CI], 0.05-0.52; P = .11), but sirolimus seemed to increase urine protein excretion (P = .002). There was no statically significant difference in leukocytes, hemoglobin, platelets, and blood pressure between groups. Aphthous stomatits and pharyngitis are reported more commonly in the sirolimus therapy group compared with the control group (P < .000001).

CONCLUSIONS

In ADPKD patients, treatment with sirolimus is safe and can effectively slow kidney growth, but it seems not to slow down the decrease of GFR.

Rash to the mTOR inhibitor everolimus: systematic review and meta-analysis

BACKGROUND

Everolimus is a mammalian target of rapamycin (mTOR) inhibitor approved for treatment of renal cell carcinoma, subependymal giant cell astrocytoma, breast cancer, and progressive neuroendocrine tumors of pancreatic origin. Its use may be hindered because of adverse events, including rash. The reported incidence and risk of a rash to everolimus varies widely and has not been closely investigated. Therefore, we conducted a systematic review and meta-analysis of the literature to determine the incidence and risk of developing a rash.

METHODS

We searched PubMed and Web of Science databases and abstracts presented at the American Society of Clinical Oncology from 1998 to December 2011 using the keyword "everolimus" to identify relevant clinical trials. Eligible studies included prospective phase II and III clinical trials of cancer patients on 10 mg of everolimus daily with available data on incidence of rash. The summary incidence and relative risk (RR) of rash were calculated using either the random-effects or fixed-effects model, depending on the heterogeneity of the constituent studies.

RESULTS

A total of 2242 patients with various malignancies from 13 clinical trials were included in the analysis. The summary incidences of all-grade and high-grade rash in patients on everolimus were 28.6% [95% confidence interval (CI), 20.8-38.0] and 1.0% (95% CI, 0.6-1.8), respectively. Everolimus was associated with a statistically significant increased risk of all-grade rash (RR=3.853, 95% CI, 2.470-6.013, P=0.000), but the RR for high-grade rash (RR=2.997, 95% CI, 0.633-14.185) was not statistically significant, with a P value of 0.166.

CONCLUSIONS

Everolimus is associated with a significant risk of developing a rash. Management of rash to everolimus is critical to prevent dose modifications and decreased quality of life, both of which can negatively affect overall clinical outcomes.

Salvage therapy with everolimus reduces the severity of treatment-refractory chronic GVHD without impairing disease control: a dual center retrospective analysis

Chronic GVHD (cGVHD) remains the most important cause of late non-relapse mortality post allogeneic hematopoietic SCT (HSCT). Although first-line treatment of cGVHD with steroids is well established, evidence for second-line treatment remains limited. Here, we report a dual center retrospective analysis of the off-label salvage treatment of steroid-refractory cGVHD with everolimus. Out of 80 patients with a median age of 50 (17-70) years, 14 (17%) suffered from mild, 39 (49%) from moderate and 27 (34%) from severe cGVHD. At the final analysis, median follow-up after introduction of everolimus was 724 (14-2205) days. Thirty-four patients (43%) required the addition of further immunosuppression during everolimus-based therapy. Global NIH Severity Score improved in 34 patients (43%), remained stable in 37 patients (46%) and worsened in 9 patients (11%). The total sum of Global NIH Severity Scores in all patients assessable was significantly reduced after treatment with everolimus (P<0.0001). Most frequent grade 3/4 toxicities included infections (n=30) and thrombocytopenia (n=15). There was a single case of relapse. Everolimus-based salvage treatment of refractory cGVHD results in significant improvement of the NIH Severity Score without impairing control of the malignant disease. Finally, these preliminary results demand further verification in prospective trials.

Racial comparisons of everolimus pharmacokinetics and pharmacodynamics in adult kidney transplant recipients

BACKGROUND

There is limited data analyzing the pharmacokinetic (PK) and pharmacodynamic (PD) properties of everolimus (EVR) between African Americans and Caucasians. The purpose of this study was to determine and compare the EVR PKs and concentration-associated efficacy and toxicity in African American and Caucasian adult kidney transplant recipients.

METHODS

This was a retrospective PK and PD analysis of all patients who received EVR at the Medical University of South Carolina Transplant Center between 2006 and 2012.

RESULTS

Forty-three patients received EVR (22 African Americans, 21 Caucasians). Baseline demographics, immunosuppression, and immunologic risk were similar between races, except for preexisting hypertension, deceased donor type, and cold ischemic time, which were higher in African American patients. PK analysis revealed that African American patients received higher initial EVR doses (2.1 ± 0.8 versus 1.6 ± 0.6 mg/d, P = 0.036), leading to higher early EVR concentrations (EVR >6 ng/mL during the first 60 days: 36% versus 10%, P = 0.037). Efficacy analysis demonstrated similar EVR effects on acute rejection rates (9% versus 10%, P = 0.961), chronic allograft changes (18% versus 14%, P = 0.729), and renal function, with both groups having improved creatinine clearance with EVR therapy (ΔeGFR: 27 versus 12 mL·min·1.73 m). Toxicity analysis demonstrated that African American patients had a trend toward higher rates of EVR discontinuation (46% versus 19%, P = 0.065) and significantly more diarrhea/gastrointestinal intolerance (73% versus 38%, P = 0.022).

CONCLUSIONS

These results demonstrate EVR therapy is effective at preventing rejection and improving graft function in both African American and Caucasian adult renal transplant patients. Conflicting with previous mammalian target of rapamycin PK/PD analyses in African American patients, this study cohort demonstrated higher early EVR levels in the African American patients.

Influence of proliferation signal inhibitors on vascular endothelial growth factor production in heart transplant recipients - preliminary report

Proliferation signal inhibitors (PSI) are especially beneficial for heart transplant recipients, but are rarely used due to frequent side effects. As they may be caused by vascular endothelial growth factor (VEGF), we performed a prospective cross-sectional pilot study to assess the influence of PSI and/or calcineurin inhibitors (CNI) presence in immunosuppressive protocols of heart transplant recipients on VEGF secretion. All electively screened heart transplant recipients willing to participate were enrolled in the study. The preliminary report was based on the results of the first 89 serum samples. The study group (n = 84) consisted of the PSI group (n = 14) further divided into the PSI + CNI subgroup (n = 10) and PSIw/oCNI subgroup (n = 4) based on concomitant CNI use, and the CNIw/oPSI group (n = 70) receiving CNI without PSI. The control group (n = 5) consisted of patients not requiring immunosuppression. VEGF was present in serum of 70 (83%) study group patients: median (range) 18 (0-316) pg/mL, mean 35 ± 57 pg/mL; in 13 (93%) PSI group patients: 22 (0-110) pg/mL, 28 ± 28 pg/mL, with 19 (8-20) pg/mL, 16 ± 6 pg/mL in the PSI + CNI subgroup, and 29 (0-110) pg/mL, 32 ± 32 pg/mL in the PSIw/oCNI subgroup. In the CNIw/oPSI group VEGF was present in 57 (81%) patients: 16 (0-316) pg/mL, 37 ± 62 pg/mL, and in the control group in 3 (60%) patients: 4 (0-110) pg/mL, 32 ± 48 pg/mL. None of the differences observed between any compared groups and/or subgroups was significant (χ² and Mann-Whitney U test). In conclusion, differences of VEGF concentration observed among groups imply the influence of PSI and CNI on VEGF production, but further studies involving higher numbers of participants are needed to prove it.

Breast cancer: current and future endocrine therapies

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

Everolimus in heart transplantation: an update

The evidence base relating to the use of everolimus in heart transplantation has expanded considerably in recent years, providing clinically relevant information regarding its use in clinical practice. Unless there are special considerations to take into account, all de novo heart transplant patients can be regarded as potential candidates for immunosuppression with everolimus and reduced-exposure calcineurin inhibitor therapy. Caution about the use of everolimus immediately after transplantation should be exercised in certain patients with the risk of severe proteinuria, with poor wound healing, or with uncontrolled severe hyperlipidemia. Initiation of everolimus in the early phase aftertransplant is not advisable in patients with severe pretransplant end-organ dysfunction or in patients on a left ventricular assist device beforetransplant who are at high risk of infection or of wound healing complications. The most frequent reason for introducing everolimus in maintenance heart transplant patients is to support minimization or withdrawal of calcineurin inhibitor therapy, for example, due to impaired renal function or malignancy. Due to its potential to inhibit the progression of cardiac allograft vasculopathy and to reduce cytomegalovirus infection, everolimus should be initiated as soon as possible after heart transplantation. Immediate and adequate reduction of CNI exposure is mandatory from the start of everolimus therapy.

Effects of immunosuppression on alpha and beta cell renewal in transplanted mouse islets

AIMS/HYPOTHESIS

Immunosuppressive drugs used in human islet transplantation interfere with the balance between beta cell renewal and death, and thus may contribute to progressive graft dysfunction. We analysed the influence of immunosuppressants on the proliferation of transplanted alpha and beta cells after syngeneic islet transplantation in streptozotocin-induced diabetic mice.

METHODS

C57BL/6 diabetic mice were transplanted with syngeneic islets in the liver and simultaneously abdominally implanted with a mini-osmotic pump delivering BrdU alone or together with an immunosuppressant (tacrolimus, sirolimus, everolimus or mycophenolate mofetil [MMF]). Glycaemic control was assessed for 4 weeks. The area and proliferation of transplanted alpha and beta cells were subsequently quantified.

RESULTS

After 4 weeks, glycaemia was significantly higher in treated mice than in controls. Insulinaemia was significantly lower in mice treated with everolimus, tacrolimus and sirolimus. MMF was the only immunosuppressant that did not significantly reduce beta cell area or proliferation, albeit its levels were in a lower range than those used in clinical settings.

CONCLUSIONS/INTERPRETATION

After transplantation in diabetic mice, syngeneic beta cells have a strong capacity for self-renewal. In contrast to other immunosuppressants, MMF neither impaired beta cell proliferation nor adversely affected the fractional beta cell area. Although human beta cells are less prone to proliferate compared with rodent beta cells, the use of MMF may improve the long-term outcome of islet transplantation.

Prognostic significance of AKT/mTOR and MAPK pathways and antitumor effect of mTOR inhibitor in NF1-related and sporadic malignant peripheral nerve sheath tumors

PURPOSE

Malignant peripheral nerve sheath tumor (MPNST) is a rare soft tissue sarcoma with poor prognosis. MPNSTs occur frequently in patients with neurofibromatosis type 1 (NF1), in which NF1 gene deficiency leads to Ras hyperactivation. Ras activation causes the subsequent activation of the AKT/mTOR and Raf/MEK/ERK pathways and regulates cellular functions. However, the activation profiles of the AKT/mTOR and MAPK pathways in MPNSTs are poorly understood. The purposes of this study are to examine the correlation between the activation of these pathways and clinicopathologic or prognostic factors and to identify candidate target molecules in MPNST. Moreover, we assessed the antitumor effects of the inhibitor of candidate target.

EXPERIMENTAL DESIGN

Immunohistochemistry was conducted to evaluate the activation profiles of AKT/mTOR and MAPK pathways using 135 tumor specimens. Immunohistochemical expressions were confirmed by Western blotting. Then, an in vitro study was conducted to examine the antitumor effect of the mTOR inhibitor on MPNST cell lines.

RESULTS

Phosphorylated-AKT (p-AKT), p-mTOR, p-S6RP, p-p70S6K, p-4E-BP1, p-MEK1/2, and p-ERK1/2 expressions were positive in 58.2%, 47.3%, 53.8%, 57.1%, 62.6%, 93.4%, and 81.3% of primary MPNSTs, respectively. Positivity for each factor showed no difference between NF1-related and sporadic MPNSTs. Univariate prognostic analysis revealed that p-AKT, p-mTOR, and p-S6RP expressions were associated with poor prognosis. Furthermore, activation of each p-mTOR and p-S6RP was an independent poor prognostic factor by multivariate analysis. mTOR inhibition by Everolimus showed antitumor activity on MPNST cell lines in vitro.

CONCLUSION

mTOR inhibition is a potential treatment option for both NF1-related and sporadic MPNSTs.

Everolimus: targeted therapy on the horizon for the treatment of breast cancer

The mammalian target of rapamycin (mTOR) is a signaling kinase of the phosphatidylinositol 3-kinase/protein kinase B (also known as Akt) signaling pathway that mediates cell growth and metabolism. Dysregulation of the mTOR pathway creates a favorable environment for the development and progression of many cancers, including breast cancer, and is associated with the development of resistance to endocrine therapy and to the anti-human epidermal growth factor receptor-2 (HER2) monoclonal antibody trastuzumab. Therefore, the addition of mTOR inhibitors to conventional breast cancer therapy has the potential to enhance therapeutic efficacy and/or overcome innate or acquired resistance. Everolimus, an mTOR inhibitor with demonstrated preclinical activity against breast cancer cell lines, has been shown to reverse Akt-induced resistance to hormonal therapy and trastuzumab. Phase I-II clinical trials have demonstrated that everolimus has promising clinical activity in women with HER2-positive, HER2-negative, and estrogen receptor-positive breast cancer when combined with HER2-targeted therapy, cytotoxic chemotherapy, and hormonal therapy, respectively. Everolimus is generally well tolerated; hematologic abnormalities and stomatitis are most common adverse events when this drug is combined with cytotoxic chemotherapy. Based on these promising results, everolimus is currently under evaluation in a series of phase III Breast Cancer Trials of Oral Everolimus (BOLERO) trials of women with HER2-positive and estrogen receptor-positive breast cancer. Results of these trials will help to establish the role of everolimus in the treatment of clinically important breast cancer subtypes.

An investigator-driven study of everolimus in surgical lung biopsy confirmed idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

We evaluated the efficacy and safety of everolimus, a macrocyclic proliferation signal inhibitor with anti-fibroproliferative activity to prevent disease progression or death in patients with IPF, a progressive, fatal disease with no known effective therapy.

METHODS

Eighty-nine patients with surgical lung biopsy confirmed IPF were enrolled in a 3-year investigator-driven, placebo-controlled, double-blinded, multicentre study of everolimus.

RESULTS

The everolimus (n = 44) and placebo (n = 45) groups were matched for demographic variables (gender, P = 0.46) and baseline lung function parameters (FVC, P = 0.29; TLC, P = 0.45; DL(CO) , P = 0.41 and PaO(2) , P = 0.34). Independent risks for disease progression were everolimus (hazard ratio (HR) 2.37, 95% CI: 1.40-4.00, P < 0.01, log rank) and male gender (HR 2.76, 95% CI: 1.47-5.17, P < 0.01, log rank). Three-year transplant-free survival was 36 ± 7% (everolimus) versus 51 ± 8% (placebo) (Kaplan-Meier, P = 0.11, log rank). Independent risks for transplant-free survival were male gender (HR 2.33, 95% CI: 1.07-5.05, P = 0.03, log rank) and baseline DL(CO) (% predicted) (HR 0.96, 95% CI: 0.93-0.99, P = 0.02, log rank).

CONCLUSIONS

Everolimus use was associated with more rapid disease progression in a well-defined cohort of patients with IPF confirmed by surgical lung biopsy followed for 3 years.

Therapeutic drug monitoring in cancer chemotherapy

For a select number of drugs, proper management of patients includes monitoring serum or plasma concentrations of the drugs and adjusting the doses accordingly - this practice is referred to as therapeutic drug monitoring (TDM). The need for TDM arises when pharmacokinetic variability of drugs is not easily accounted for by common clinical parameters. Many chemotherapeutic drugs have large interindividual variability, yet TDM is not commonplace in chemotherapy management. This review will discuss pharmacokinetics in the context of chemotherapeutic drugs, examine the few instances where TDM is currently used in the field of oncology and propose other drugs where TDM might be useful for dose adjustments in the management of chemotherapy.

Evaluation of the novel protein kinase C inhibitor sotrastaurin as immunosuppressive therapy after renal transplantation

IMPORTANCE OF THE FIELD

The prevalence of acute renal allograft rejection has decreased substantially in past decades due to new and more specific immunosuppressive compounds but improvements in long-term graft function have not been achieved. There is a large need for new immunosuppressive agents that lack toxicity of current agents such as calcineurin inhibitors but show high synergistic efficiency in preventing rejection processes.

AREAS COVERED IN THIS REVIEW

This review summarizes data concerning the pharmacokinetics, pharmacodynamics and clinical efficacy of the new PKC inhibitor sotrastaurin with a focus on renal transplantation. The article contains information that has been presented at international transplant meetings and congresses and that has been published between 2006 and 2010. Additionally, current ongoing trials are described in detail.

WHAT THE READER WILL GAIN

Immunosuppressive regimens after kidney transplantation consist of a combination of several agents in order to minimize drug toxicity. Therefore, the reader is presented with the most up-to-date/current developments in sotrastaurin applications in Phase I and II trials with emphasis on data maintained from studies that combined sotrastaurin with established agents such as mycophenolic acid and tacrolimus.

TAKE HOME MESSAGE

Several trials are ongoing and planned to determine the optimal immunosuppressive regimen to benefit from sotrastaurin's distinct mechanism of action.

Everolimus for subependymal giant-cell astrocytomas in tuberous sclerosis

BACKGROUND

Neurosurgical resection is the standard treatment for subependymal giant-cell astrocytomas in patients with the tuberous sclerosis complex. An alternative may be the use of everolimus, which inhibits the mammalian target of rapamycin, a protein regulated by gene products involved in the tuberous sclerosis complex.

METHODS

Patients 3 years of age or older with serial growth of subependymal giant-cell astrocytomas were eligible for this open-label study. The primary efficacy end point was the change in volume of subependymal giant-cell astrocytomas between baseline and 6 months. We gave everolimus orally, at a dose of 3.0 mg per square meter of body-surface area, to achieve a trough concentration of 5 to 15 ng per milliliter.

RESULTS

We enrolled 28 patients. Everolimus therapy was associated with a clinically meaningful reduction in volume of the primary subependymal giant-cell astrocytoma, as assessed on independent central review (P<0.001 for baseline vs. 6 months), with a reduction of at least 30% in 21 patients (75%) and at least 50% in 9 patients (32%). Marked reductions were seen within 3 months and were sustained. There were no new lesions, worsening hydrocephalus, evidence of increased intracranial pressure, or necessity for surgical resection or other therapy for subependymal giant-cell astrocytoma. Of the 16 patients for whom 24-hour video electroencephalography data were available, seizure frequency for the 6-month study period (vs. the previous 6-month period) decreased in 9, did not change in 6, and increased in 1 (median change, -1 seizure; P=0.02). The mean (±SD) score on the validated Quality-of-Life in Childhood Epilepsy questionnaire (on which scores can range from 0 to 100, with higher scores indicating a better quality of life) was improved at 3 months (63.4±12.4) and 6 months (62.1±14.2) over the baseline score (57.8±14.0). Single cases of grade 3 treatment-related sinusitis, pneumonia, viral bronchitis, tooth infection, stomatitis, and leukopenia were reported.

CONCLUSIONS

Everolimus therapy was associated with marked reduction in the volume of subependymal giant-cell astrocytomas and seizure frequency and may be a potential alternative to neurosurgical resection in some cases, though long-term studies are needed. (Funded by Novartis; ClinicalTrials.gov number, NCT00411619.).

Zoledronic acid potentiates mTOR inhibition and abolishes the resistance of osteosarcoma cells to RAD001 (Everolimus): pivotal role of the prenylation process

Despite recent improvements in therapeutic management of osteosarcoma, ongoing challenges in improving the response to chemotherapy warrants new strategies still needed to improve overall patient survival. In this study, we investigated in vivo the effects of RAD001 (Everolimus), a new orally available mTOR inhibitor, on the growth of human and mouse osteosarcoma cells either alone or in combination with zoledronate (ZOL), an anti-osteoporotic drug used to treat bone metastases. RAD001 inhibited osteosarcoma cell proliferation in a dose- and time-dependent manner with no modification of cell-cycle distribution. Combination with ZOL augmented this inhibition of cell proliferation, decreasing PI3K/mTOR signaling compared with single treatments. Notably, in contrast to RAD001, ZOL downregulated isoprenylated membrane-bound Ras concomitantly with an increase of nonisoprenylated cytosolic Ras in sensitive and resistant osteosarcoma cell lines to both drugs. Moreover, ZOL and RAD001 synergized to decrease Ras isoprenylation and GTP-bound Ras levels. Further, the drug combination reduced tumor development in two murine models of osteoblastic or osteolytic osteosarcoma. We found that ZOL could reverse RAD001 resistance in osteosarcoma, limiting osteosarcoma cell growth in combination with RAD001. Our findings rationalize further study of the applications of mTOR and mevalonate pathway inhibitors that can limit protein prenylation pathways.