Stem cell-like transcriptional reprogramming mediates metastatic resistance to mTOR inhibition

Inhibitors of the mechanistic target of rapamycin (mTOR) are currently used to treat advanced metastatic breast cancer. However, whether an aggressive phenotype is sustained through adaptation or resistance to mTOR inhibition remains unknown. Here, complementary studies in human tumors, cancer models and cell lines reveal transcriptional reprogramming that supports metastasis in response to mTOR inhibition. This cancer feature is driven by EVI1 and SOX9. EVI1 functionally cooperates with and positively regulates SOX9, and promotes the transcriptional upregulation of key mTOR pathway components (REHB and RAPTOR) and of lung metastasis mediators (FSCN1 and SPARC). The expression of EVI1 and SOX9 is associated with stem cell-like and metastasis signatures, and their depletion impairs the metastatic potential of breast cancer cells. These results establish the mechanistic link between resistance to mTOR inhibition and cancer metastatic potential, thus enhancing our understanding of mTOR targeting failure.

Population pharmacokinetic modeling for intravenous temsirolimus and sirolimus metabolite in subjects with various solid tumors

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Background: Temsirolimus (TEMSR) is an mTOR inhibitor approved for treatment of patients with advanced renal cell carcinoma, and under development for relapsed/refractory mantle cell lymphoma (MCL). In MCL, TEMSR showed a dose-related increase in median progression-free survival [4.8 vs. 3.4 mo] and objective response rate [22% vs 6%] for 175 mg x 3 wks then 75 or 25 mg weekly regimens (175/75-mg and 175/25-mg), respectively. We aim to characterize the population pharmacokinetic exposure, covariate influence, and differences afforded by these regimens. Methods: Nonlinear mixed-effects models of TEMSR and sirolimus (SIR; major active metabolite) blood concentrations were defined in healthy subjects and patients. Modeling for TEMSR employed a 4-compartment model with saturable distribution to red cells and peripheral tissue, and modeling for SIR utilized a linear 2- compartment model with factor for dose. Covariates included demographic factors, clinical labs, and disease condition. Following validation, simulations with variability were used to evaluate effects of covariates on exposure. Results: Final datasets comprised 1342 observations from 150 subjects (TEMSR) and 1648 observations from 279 subjects (SIR). In a typical patient (56-year-old male weighing 76.5 kg), disease affected TEMSR clearance (62.4 L/h in MCL, 92.1 L/h in breast cancer vs. 112 L/h for other subjects). Dose, single vs. multiple, and body weight affected SIR apparent clearance. Simulations for the 175/75-mg regimen indicate that significant covariates yield only modest differences on blood exposures. For MCL (175/75-mg regimen), TEMSR Cmax (week 3) was 2574 ng/mL and SIR Ctrough (week 6) was 10.7 ng/mL. AUC for the 75-mg maintenance arm was ∼2.3-fold (TEMSR) and ∼3.5-fold higher (SIR) than respective values of the 25-mg arm. Correlation of average AUC to clinical response was not apparent. Conclusions: No significant differential effects were observed for age, gender, race, or hepatic and renal laboratory measures. Covariates of disease, while significant, have only modest effects on the exposure profile. Higher clinical responses observed with the 175/75-mg regimen as compared with the 175/25-mg regimen may critically derive from differences in exposure.

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A single-dose, placebo- and moxifloxacin-controlled 3-period study of the effects of temsirolimus on cardiac repolarization in healthy subjects

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Background: Temsirolimus (CCI-779) is a novel selective inhibitor of the mammalian target of rapamycin (mTOR) approved by the US FDA for the treatment of patients with advanced renal cell carcinoma. This study was designed to assess the effect of a single dose of 25 mg IV temsirolimus on the corrected QT interval (QTc) in healthy subjects. Methods: Fifty-eight (58) healthy subjects were enrolled in this 3-period crossover study. In periods 1 and 2, subjects were administered IV placebo either alone or with open-label oral moxifloxacin. In period 3, subjects were administered 25 mg IV temsirolimus. Serial ECGs were digitally captured in triplicate and manually over read by a central vendor. The primary statistical objective was to estimate the effect of temsirolimus compared with placebo on change from time-matched baseline QTc at the end of infusion (0.5 hour time point). Secondary endpoints and objectives included estimates of effect at 12 additional time points, population PKPD analyses, and categorical summaries of interval data. Assay sensitivity was evaluated by the effect of moxifloxacin on change from time-matched baseline QTc as compared with placebo. Results: Temsirolimus had no effect on the QTc interval in the primary analysis. At 11 of 12 secondary time points, the upper bound for the temsirolimus QTc 90% CIs for the time-matched change from baseline difference from placebo was less than 10 msec without evidence of QTc trends or relationship to temsirolimus or sirolimus whole blood concentrations. Mean concentrations were comparable to those observed in patients with renal cell carcinoma following administration of 25 mg IV temsirolimus. Moxifloxacin produced a statistically significant increase in the QTc interval as compared with placebo. No relevant PKPD relationship was seen using linear or Emax models. No subject in this study had a QTc interval exceeding 450 msec and no subjects had a change from baseline >30 msec. Conclusions: We conclude that therapeutic exposures of temsirolimus are not associated with changes in QTc interval that reach the level of regulatory significance, according to ICH E14 guidance. The findings are consistent with the lack of QTc interval prolongation observed in studies of cancer patients.

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Phase II trial of temsirolimus (CCI-779) in recurrent glioblastoma multiforme: a North Central Cancer Treatment Group Study

BACKGROUND

Temsirolimus (CCI-779) is a small-molecule inhibitor of the mammalian target of rapamycin (mTOR) and represents a rational therapeutic target against glioblastoma multiforme (GBM).

METHODS

Recurrent GBM patients with < or = 1 chemotherapy regimen for progressive disease were eligible. Temsirolimus was administered in a 250-mg intravenous dose weekly.

RESULTS

Sixty-five patients were treated. The incidence of grade 3 or higher nonhematologic toxicity was 51%, and consisted mostly of hypercholesterolemia (11%), hypertriglyceridemia (8%), and hyperglycemia (8%). Grade 3 hematologic toxicity was observed in 11% of patients. Temsirolimus peak concentration (Cmax), and sirolimus Cmax and area under the concentration-time curve were decreased in patients receiving p450 enzyme-inducing anticonvulsants (EIACs) by 73%, 47%, and 50%, respectively, but were still within the therapeutic range of preclinical models. Twenty patients (36%) had evidence of improvement in neuroimaging, consisting of decrease in T2 signal abnormality +/- decrease in T1 gadolinium enhancement, on stable or reduced steroid doses. Progression-free survival at 6 months was 7.8% and median overall survival was 4.4 months. Median time to progression (TTP) for all patients was 2.3 months and was significantly longer for responders (5.4 months) versus nonresponders (1.9 months). Development of grade 2 or higher hyperlipidemia in the first two treatment cycles was associated with a higher percentage of radiographic response (71% v 31%; P = .04). Significant correlation was observed between radiographic improvement and high levels of phosphorylated p70s6 kinase in baseline tumor samples (P = .04).

CONCLUSION

Temsirolimus is well tolerated in recurrent GBM patients. Despite the effect of EIACs on temsirolimus metabolism, therapeutic levels were achieved. Radiographic improvement was observed in 36% of temsirolimus-treated patients, and was associated with significantly longer TTP. High levels of phosphorylated p70s6 kinase in baseline tumor samples appear to predict a patient population more likely to derive benefit from treatment. These findings should be validated in other studies of mTOR inhibitors.

Population-based pharmacokinetics of the soluble TNFr etanercept: a clinical study in 43 patients with ankylosing spondylitis compared with post hoc data from patients with rheumatoid arthritis

OBJECTIVE

The purpose of this study was to evaluate the pharmacokinetics of etanercept in patients with ankylosing spondylitis (AS) in a phase 3 study.

METHODS

Serum etanercept concentrations were analyzed from samples obtained at weeks 4 and 12 from 43 patients with AS (median age: 45 years; median body weight: 75 kg; white/non-white: 40/3; male/female: 34/9) receiving 25 mg subcutaneously twice weekly for 12 weeks. A population pharmacokinetics analysis using NONMEM was conducted to estimate individual etanercept pharmacokinetic parameters. Initially, appropriate base and covariate population pharmacokinetic models were built based on data from 10 prior clinical studies of etanercept administered subcutaneously or intravenously to healthy subjects (n = 53) and to patients with rheumatoid arthritis (RA) (n = 212). The influence of demographic characteristics on the pharmacokinetics of etanercept was thoroughly evaluated. The stability of the final model was evaluated using both internal (bootstrapping) and external (data splitting) validation approaches. Finally, the selected final population covariate model was used to estimate the Bayesian pharmacokinetic parameters for the patients with AS.

RESULTS

The data from the 10 prior clinical studies were optimally fitted to a 2-compartment linear population covariate model. Both age (< 17 years) and body weight (< 60 kg) were found to be important covariates on clearance. Both bootstrapping and data splitting validated the population model. The mean Bayesian-predicted etanercept clearance and steady-state trough concentration were 0.072 l/h and 2,004 ng/ml, respectively. The pharmacokinetic parameters of etanercept in the patients with AS were similar to those observed in the patients with RA.

CONCLUSIONS

The pharmacokinetics of etanercept in patients with AS were similar to those in patients with RA. The AS disease state does not appear to alter the disposition of etanercept.

Phase I and pharmacokinetic study of CCI-779, a novel cytostatic cell-cycle inhibitor, in combination with 5-fluorouracil and leucovorin in patients with advanced solid tumors

BACKGROUND

CCI-779 is a novel ester of the immunosuppressive agent sirolimus that exerts cytostatic effects by the inhibition of the translation of cell-cycle regulatory proteins. We investigated the maximum tolerated dose (MTD) and pharmacokinetics (PK) of CCI-779 in combination with leucovorin (LV) and 5-fluorouracil (5-FU) in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients were treated with LV at 200 mg/m(2) as a 1-h i.v. infusion directly followed by continuous 24-h i.v. infusion of 5-FU, in the first patient at 2000 mg/m(2) and in subsequent patients at 2600 mg/m(2). CCI-779 was administered directly prior to LV as a 30-min i.v. infusion at a starting dose of 15 mg/m(2) beginning at day 8 and escalated in subsequent cohorts of patients. One cycle consisted of six weekly administrations followed by 1 week of rest. Blood samples were drawn to assess PK of CCI-779 as well as its effect on steady-state 5-FU exposures.

RESULTS

Twenty-eight patients entered the study, the majority having tumor types for which 5-FU is used as a treatment. CCI-779 doses of 15, 25, 45 and 75 mg/m(2) were investigated. Skin toxicity (rash) was prominent at all dose levels examined. Stomatitis was the dose-limiting toxicity (DLT) for 75 mg/m(2) doses of CCI-779. Subsequently the cohort at 45 mg/m(2) was expanded to a total of 15 patients, and at this dose level two treatment-related deaths occurred due to mucositis with bowel perforation. Based on the toxicities observed, it was decided to discontinue the study. Partial responses were observed in three patients with gastrointestinal tumors. No pharmacokinetic interaction between CCI-779 and 5-FU was observed.

CONCLUSIONS

The safety profiles of CCI-779 and 5-FU/LV suggest an overlap of drug-related toxicities, and the administration of these drugs at these doses and schedule resulted in unacceptable toxicity and therefore cannot be recommended. If CCI-779 is to be used in combination with 5-FU/LV, other doses or schedules of administration will need to be explored.

Pharmacokinetic and pharmacodynamic action of etodolac in patients after oral surgery

The objective of this double-blind, randomized, parallel-group study was to evaluate the pharmacokinetics of etodolac and the pharmacodynamic response of pain in patients following oral surgery who had received 200 or 400 mg of etodolac immediate release (IR), 400 or 1200 mg of etodolac extended release (ER), or a placebo. Etodolac concentrations in 441 plasma samples from 187 patients were analyzed for population pharmacokinetics using the NONMEM program. A one-compartment pharmacokinetic model with first-order absorption described the observed data. For etodolac IR, the population mean (%CV) estimates were 3.01 L/h (5.3%) for clearance, 13.6 L (6.8%) for volume of distribution, and 2.31 h-1 (33%) for ka. Respective values for etodolac ER were 3.68 L/h (11%) for clearance, 24.3 L (22%) for volume of distribution, and 0.172 h-1 (24%) for ka. These values generally agreed with previously reported values in healthy adults. Pharmacodynamic assessments included collection of a four-level categorical rating of pain intensity for up to 24 hours after treatment. Pain intensity difference scores were temporally related to etodolac concentrations and were described using an indirect response model. Mean (%CV) pharmacodynamic parameters were IC50 of 14.0 mg/L (9.5%), kout of 1.62 h-1 (13%), FR of 0.56 (8.2%), and Hill coefficients that ranged from 1.26 to 3.34 units. A single 1200 mg dose of etodolac ER given once daily was shown to provide substantial efficacy for 13 hours after dose, modest effect through 24 hours, and a more sustained duration of action than the IR dosage form.

Steady-state pharmacokinetics of idebenone in healthy volunteers

An open study was conducted with 12 healthy male Caucasian volunteers to determine the single dose and steady-state pharmacokinetics in plasma after a total daily dose of 90 mg of idebenone administered as 45 mg twice daily for 10 consecutive days. In the dose regimen investigated, multiple daily doses of 90 mg of idebenone were well tolerated by healthy male volunteers and were not associated with any clinically relevant changes in ECG or clinical laboratory parameters. The results of the physical examinations after study termination revealed normal findings in all volunteers. To evaluate the single dose and steady-state pharmacokinetic profile, blood samples were collected at predetermined time points during the study. In those subjects examined, generally good systemic exposure with rapid absorption of idebenone was obtained throughout the entire dosing period. Exposures to idebenone and its metabolites after both single and repeated oral doses of idebenone were comparable in magnitude. Further, the exposures attained were generally consistent with those observed in a previous study after 30 mg three times daily. All pharmacokinetic assessments were associated with a low to moderate degree of inter-subject variability.

T cell hybridomas define the class II MHC-restricted response to vesicular stomatitis virus infection

T cell hybridomas with specificity for VSV (vesicular stomatitis virus)-infected cells were generated in an attempt to better define the la-restricted helper T cell response to VSV. The hybridomas were created by fusing BALB/c (H-2d) anti-VSV immune spleen cells to the murine thymoma BW 5147. These hybridomas produce IL-2 when stimulated with VSV-infected spleen cells. They were found to recognize viral antigens in association with I-Ad and, in addition, could also be stimulated by VSV-infected A20 cells (an Ia-positive B cell lymphoma of H-2d origin). The purified viral membrane glycoprotein, G protein, and Gs (secreted G protein that lacks the hydrophobic and intracytoplasmic domains) both stimulated IL-2 production when added to cultures of A20 and the hybridomas. These hybridomas therefore recognize a viral antigenic determinant on G protein. Since chemically-fixed antigen-presenting cells fail to stimulate the hybridomas after exogenous addition of purified G protein we can conclude that these T cell hybridomas recognize a processed form of the G protein. Stimulator cells created by expression in A20 of a transfected cDNA encoding G protein were also recognized. Recognition in this case was I-Ad-restricted, as anti-I-Ad monoclonal antibodies blocked stimulation, and an Ia-negative cell (P815) expressing a transfected G protein gene failed to stimulate the hybridomas. Even after paraformaldehyde fixation, G gene-transfected, Ia-positive cells could stimulate the hybridomas, suggesting that processing of this endogenously-synthesized antigen has occurred.

Contamination of illicit phencyclidine with 1-piperidinocyclohexanecarbonitrile

A retrospective study of illicit phencyclidine (PCP), which consisted of 94 different cases or 213 individual samples, has shown that one third of both the powder/tablets and green plant material contained the synthetic contaminant 1-piperidinocyclohexanecarbonitrile (PCC). The mole % PCC/PCP ranged from 1 to 68%. The method of analysis was gas chromatography (3% OV-7, 205 degrees C) and in preparation for analysis the sample was dissolved directly in chloroform or extracted from a strongly acidic solution (0.1 N HCl). Using these extraction conditions PCC was found not to undergo measurable decomposition.