Everolimus for the treatment of lymphangioleiomyomatosis: a phase II study.

Lymphangioleiomyomatosis is a rare, progressive cystic lung disorder characterised by dysregulated activation of mammalian target of rapamycin (mTOR) signalling.This was a phase IIa, multicentre, open-label study of the mTOR inhibitor everolimus (2.5 mg·day(-1) escalated to 10 mg·day(-1)) in 24 women with lymphangioleiomyomatosis. Primary endpoints were safety, pharmacokinetics and serum vascular endothelial growth factor-D (VEGF-D) levels; secondary endpoints were measures of lung function.Following 26 weeks of everolimus treatment, forced vital capacity exhibited stability, while forced expiration volume in 1 s improved from baseline, with mean changes (95% confidence interval) of 10 mL (-111-132) and 114 mL (11-217), respectively; 6-min walk distance improved by 47 m. Median VEGF-D and collagen IV levels decreased from baseline, from 1730 pg·mL(-1) to 934.5 pg·mL(-1), and 103 ng·mL(-1) to 80.5 ng·mL(-1), respectively. Adverse events were mostly grade 1-2; mouth ulceration, headache, nausea, stomatitis and fatigue were common. Serious adverse events suspected to be treatment related included peripheral oedema, pneumonia, cardiac failure and Pneumocystis jirovecii infection. Everolimus blood levels increased dose proportionally.In this study, everolimus improved some measures of lung function and exercise capacity and reduced serum VEGF-D and collagen IV. Side effects were generally consistent with known toxicities of mTOR inhibitors, although some were severe.

Sotrastaurin single-dose pharmacokinetics in de novo liver transplant recipients.

Sotrastaurin is a protein kinase C inhibitor in development for prevention of rejection after liver transplantation. In a pharmacokinetic study, 13 de novo liver transplant recipients received 100 mg sotrastaurin once between days 1-3 and once between days 5-8 post-transplant. Sotrastaurin absorption based on the area under the concentration-time curve (AUC) of total drug in blood (3544 ± 1434 ng·h/ml) was similar to that of healthy subjects in a previous study (4531 ± 1650 ng·h/ml). However, the sotrastaurin binding protein, α1-acid glycoprotein, was nominally higher in patients (1.07 ± 0.28 vs. 0.87 ± 0.16 g/l, P = 0.13) yielding a 60% lower AUC based on free drug versus that in healthy subjects (27 ± 13 vs. 62 ± 15 ng·h/ml, P < 0.0001). There was minor excretion of sotrastaurin in drained bile (1% of dose) consistent with the fact that sotrastaurin is extensively metabolized leaving little unchanged drug to excrete. In the first week after liver transplantation, sotrastaurin is bioavailable after oral administration. However, patients with elevated α1-acid glycoprotein levels may have lower free drug concentrations. Whether a higher dose of sotrastaurin is needed to compensate for this in the short-term after surgery will be addressed in future clinical trials.

Overview of sotrastaurin clinical pharmacokinetics.

Sotrastaurin (AEB071) is an investigational immunosuppressant that blocks T-lymphocyte activation through protein kinase C inhibition. It is currently in Phase II of clinical development for the prevention of acute rejection after solid organ transplantation. In renal transplant clinical trials, sotrastaurin has been administered at doses of 200 to 300 mg twice daily. Using a validated liquid chromatography method with tandem mass spectrometry, steady-state predose blood concentrations averaged approximately 600 and 900 ng/mL at these dose levels, respectively. Sotrastaurin is primarily metabolized through CYP3A4. There is one active metabolite, N-desmethyl-sotrastaurin, that is present at low blood concentrations (less than 5% of the parent exposure). The elimination half-life of sotrastaurin averages 6 hours. Clinical drug interaction studies to date have demonstrated that sotrastaurin increases the area under the concentration-time curve of everolimus 1.2-fold and of tacrolimus twofold. Conversely, sotrastaurin area under the concentration-time curve is increased up to 1.8-fold by cyclosporine and 4.6-fold by ketoconazole. Blood samples from renal transplant patients receiving sotrastaurin were stimulated ex vivo by protein kinase C-dependent pathways. Inhibition of cytokine production, expression of CD69, and thymidine uptake served as biomarkers that demonstrated the ability of sotrastaurin to inhibit T-cell activation and proliferation at the doses used in these studies. Phase II trials have paired sotrastaurin with tacrolimus, mycophenolic acid, or everolimus. The clinical and pharmacokinetic results of these and upcoming trials will determine the optimal immunosuppressive regimen to benefit from sotrastaurin's novel mechanism of action and whether therapeutic drug monitoring will be beneficial.

Sotrastaurin and cyclosporine drug interaction study in healthy subjects.

INTRODUCTION: Sotrastaurin is an immunosuppressant that inhibits protein kinase C and blocks T-lymphocyte activation. The authors determined the effect of combining sotrastaurin with the calcineurin inhibitor cyclosporine on the pharmacokinetics and biomarker responses to both drugs. METHODS: This was a randomized, 4-period, crossover study in 20 healthy subjects who received single oral doses of (1) sotrastaurin 100 mg, (2) cyclosporine 400 mg, (3) 100 mg sotrastaurin with 100 mg cyclosporine and (4) 100 mg sotrastaurin with 400 mg cyclosporine. Blood samples were collected to measure drug levels and biomarkers of T-lymphocyte activation (interleukin-2 and tumor necrosis factor producing T-cells and interleukin-2 messenger RNA levels) and of T-lymphocyte proliferation (thymidine uptake). RESULTS: Sotrastaurin did not alter cyclosporine AUC; however, low-dose and high-dose cyclosporine increased sotrastaurin AUC by 1.2-fold [90% confidence interval, 1.1-1.4] and 1.8-fold [1.6-2.1], respectively. Adding high-dose cyclosporine to a low-therapeutic dose of sotrastaurin significantly enhanced the inhibition of cytokine production by 31% [95% confidence interval, 25-36%], of interleukin-2 messenger RNA levels by 13% [7-19%], and of thymidine uptake by 37% [32-42%] compared with sotrastaurin alone. Addition of low-dose cyclosporine elicited slightly lower enhancements in inhibition by 21% [14-28%], 6% [-4-16%], and 26% [21-30%], respectively, compared with sotrastaurin alone. CONCLUSIONS: Sotrastaurin did not alter the pharmacokinetics of cyclosporine, but cyclosporine increased sotrastaurin AUC up to 1.8-fold. The combined drugs elicited a significantly greater inhibition of T-cell activation and proliferation than sotrastaurin alone.

Ketoconazole increases fingolimod blood levels in a drug interaction via CYP4F2 inhibition.

The sphingosine-1-phosphate receptor modulator fingolimod is predominantly hydroxylated by cytochrome CYP4F2. In vitro experiments showed that ketoconazole significantly inhibited the oxidative metabolism of fingolimod by human liver microsomes and by recombinant CYP4F2. The authors used ketoconazole as a putative CYP4F2 inhibitor to quantify its influence on fingolimod pharmacokinetics in healthy subjects. In a 2-period, single-sequence, crossover study, 22 healthy subjects received a single 5-mg dose of fingolimod in period 1. In period 2, subjects received ketoconazole 200 mg twice daily for 9 days and a single 5-mg dose of fingolimod coadministered on the 4th day of ketoconazole treatment. Ketoconazole did not affect fingolimod t(max) or half-life, but there was a weak average increase in C(max) of 1.22-fold (90% confidence interval, 1.15-1.30). The AUC over the 5 days of ketoconazole coadministration increased 1.40-fold (1.31-1.50), and the full AUC to infinity increased 1.71-fold (1.53-1.91). The AUC of the active metabolite fingolimod-phosphate was increased to a similar extent by 1.67-fold (1.50-1.85). Ketoconazole predose plasma levels were not altered by fingolimod. The magnitude of this interaction suggests that a proactive dose reduction of fingolimod is not necessary when adding ketoconazole to a fingolimod regimen. The clinician, however, should be aware of this interaction and bear in mind the possibility of a fingolimod dose reduction based on clinical monitoring.

The effect on sotrastaurin pharmacokinetics of strong CYP3A inhibition by ketoconazole.

AIMS: Sotrastaurin is an immunosuppressant that reduces T-lymphocyte activation via protein kinase C inhibition. The effect of CYP3A4 inhibition by ketoconazole on the pharmacokinetics of sotrastaurin, a CYP3A4 substrate, was investigated. METHODS: This was a two-period, single-sequence crossover study in 18 healthy subjects. They received a single 50 mg oral dose of sotrastaurin in period 1 followed by a 14-day inter-treatment phase. In period 2 they received ketoconazole 200 mg twice daily for 6 days and a single 50 mg dose of sotrastaurin on the fourth day of ketoconazole administration. RESULTS: Co-administration of single-dose sotrastaurin during steady-state ketoconazole increased sotrastaurin C(max) by 2.5-fold (90% confidence interval 2.2, 2.9) from 285 +/- 128 to 678 +/- 189 ng ml(-1) and increased AUC by 4.6-fold (4.1, 5.2) from 1666 +/- 808 to 7378 +/- 3011 ng ml(-1) h. Sotrastaurin half-life was nearly doubled from 5.9 +/- 1.7 to 10.6 +/- 2.5 h. The AUC of the active metabolite N-desmethyl-sotrastaurin was increased by 6.8-fold. Sotrastaurin did not alter ketoconazole steady-state predose plasma concentrations. CONCLUSIONS: The strong CYP3A4 inhibitor ketoconazole increased sotrastaurin AUC by 4.6-fold. A compensatory reduction in the dose of sotrastaurin is warranted when strong CYP3A4 inhibitors are co-administered.

A mechanistic study to assess whether isoproterenol can reverse the negative chronotropic effect of fingolimod.

The sphingosine-1-phosphate receptor modulator fingolimod (FTY720) elicits a negative chronotropic effect at treatment initiation that attenuates thereafter. The authors determined whether isoproterenol can counteract this effect. In this randomized, crossover study, 14 healthy subjects received 5 infusions of isoproterenol (titrated to increase heart rate to 100-120 bpm) or intravenous placebo. The first infusion was 2 hours before and the other 4 infusions were between 3 and 6 hours after a 5-mg oral dose of fingolimod. Telemetry and pharmacokinetic data were collected for 24 hours. During isoproterenol infusion 1 (before fingolimod administration), heart rate was increased 80% from preinfusion 68 +/- 9 bpm to a maximum 122 +/- 15 bpm. Administration of fingolimod decreased heart rate from 73 +/- 11 bpm predose to a nadir of 57 +/- 8 bpm. The subsequent isoproterenol infusion 2 in the presence of fingolimod increased mean heart rate by 85% to a maximum 105 +/- 21 bpm. A 41% higher total isoproterenol dose was needed to increase heart rate to the target range with fingolimod (97 +/- 6 mcg) compared with isoproterenol alone (69 +/- 27 mcg). Isoproterenol infusions 3 to 5 had similar effects on heart rate as infusion 2. Fingolimod had no significant influence on blood pressure responses to isoproterenol. Isoproterenol did not alter the pharmacokinetics of fingolimod. The pure beta-agonist isoproterenol can reverse the heart rate reduction that occurs transiently after initiating fingolimod treatment.

The ability of atropine to prevent and reverse the negative chronotropic effect of fingolimod in healthy subjects.

AIMS: The authors determined whether intravenous atropine can prevent or counteract the negative chronotropic effect of the immunomodulator fingolimod. METHODS: In this randomized, placebo-controlled, two-period, crossover study, 12 healthy subjects received 5 mg fingolimod orally concurrently with intravenous atropine (titrated to a heart rate of 110-120 beats min(-1)) or intravenous placebo. A second group of 12 subjects received atropine/placebo 4 h after the fingolimod dose. Continuous telemetry measurements were made for 24 h after each fingolimod dose. RESULTS: Fingolimod administration alone yielded a heart rate nadir of 51 +/- 5 beats min(-1) at a median 4 h postdose with heart rate remaining depressed at 51-64 beats min(-1) over the rest of the day. Concurrent administration of fingolimod and atropine yielded a nadir of 66 +/- 6 beats min(-1) resulting in an atropine: placebo ratio (90% confidence interval) of 1.30 (1.22, 1.36). When atropine was administered at the time of the nadir, it was able to reverse the negative chronotropic effect of fingolimod from a heart rate of 56 +/- 9 beats min(-1) (placebo) to 64 +/- 8 beats min(-1) (atropine) resulting in an atropine: placebo ratio of 1.15 (1.04, 1.26). Atropine had no influence on the pharmacokinetics of fingolimod. CONCLUSIONS: Atropine administered concurrently with fingolimod prevented the heart rate nadir that typically occurs 4 h postdose. Atropine administered at the time of the heart rate nadir was able to reverse the negative chronotropic effect of fingolimod.

Cyclosporine pharmacokinetics and blood pressure responses after conversion to once-daily dosing in maintenance liver transplant patients.

In this six-month randomized multicenter trial, we characterized cyclosporine pharmacokinetics and blood pressure profiles in maintenance liver transplant patients converting from twice-daily to once-daily cyclosporine dosing. A total of 60 patients were randomized as follows: group A (n = 14) maintained twice-daily dosing; group B (n = 24) converted to once-daily dosing at the same total daily dose as pre-conversion; and group C (n = 22) was treated the same as group B but with a 25% reduction in dose and C2 at two to three wk post-conversion. After conversion to once-daily dosing in groups B and C, trough blood levels (C0) did not change; whereas, C2 nearly doubled. The total daily area under the concentration-time curve AUC(0-24) increased by 29%. After the dose reduction in group C, the AUC(0-24) was similar to the pre-conversion value. Hence, a 25-30% dose reduction can be considered after conversion to once-daily dosing. In the study observation period in weeks 4-15, the median (25-75 percentile) C2 was 568 (469-750) ng/mL for group A; 1055 (840-1224) ng/mL for group B; and 764 (575-959) ng/mL for group C. Conversion to once-daily dosing was associated with a decrease in nighttime mean arterial blood pressure.

The effect on heart rate of combining single-dose fingolimod with steady-state atenolol or diltiazem in healthy subjects.

OBJECTIVE: The sphingosine-1-phosphate receptor modulator fingolimod (FTY720) is known to elicit a negative chronotropic effect at treatment initiation that attenuates over time with continued dosing. The authors determined the effect of combining a single dose of fingolimod with steady-state atenolol or diltiazem on heart rate and mean arterial pressure. METHODS: In a partially randomized, single-blind, placebo-controlled, three-period, crossover study, 25 healthy subjects received (1) a single oral 5-mg dose of fingolimod, (2) either 50 mg atenolol or 240 mg diltiazem once daily for 5 days, and (3) the antihypertensive for 5 days and a single dose of fingolimod on day 5. Telemetry and pharmacokinetic data were collected. RESULTS: The daytime mean heart rate nadir was 15% lower when fingolimod was combined with atenolol (42 +/- 7 bpm) compared with fingolimod alone (51 +/- 9 bpm) yielding a combination/monotherapy ratio of 0.85 (90%CI, 0.79-0.92). The daytime mean heart rate nadir from fingolimod alone (55 +/- 5 bpm) was not altered when combined with diltiazem (56 +/- 8 bpm) yielding a ratio of 0.99 (0.94-1.05). There was no clinically relevant change in mean arterial pressure when fingolimod was administered with atenolol or diltiazem compared with administration of the drugs alone in normotensive subjects. The pharmacokinetics of the drugs were not altered during coadministration. CONCLUSION: Adding fingolimod to a beta-blocker such as atenolol resulted in a moderately lower mean heart rate nadir compared with fingolimod alone. However, subjects who had a stronger negative chronotropic response to fingolimod alone (nadir < 50 bpm) had minimal or no further reduction in heart rate with the drug combination. Adding fingolimod to a calcium channel blocker such as diltiazem did not further lower the heart rate compared to fingolimod alone.

α4-integrin receptor desaturation and disease activity return after natalizumab cessation.

OBJECTIVE: To describe the time course of α4-integrin receptor desaturation and disease activity return in patients with relapsing-remitting MS who discontinued natalizumab and to investigate baseline and on-study predictors for the recurrence of disease activity. METHODS: In the course of TOFINGO, a 32-week, patient- and rater-blinded multicenter, parallel-group study, we performed MRI, counted relapses, and measured α4-integrin receptor occupancy (RO) at baseline and 8, 12, 16, 20, and 24 weeks. The relationship between RO and total number of new T1 gadolinium-enhancing (Gd+) lesions was modeled using Poisson linear regression. RESULTS: Patients (N = 142) were randomized (1:1:1) to 8-, 12-, or 16-week washout (WO) groups. At randomization, the median RO in the 8-, 12-, and 16-week WO groups was 94.5%, 92.4%, and 90.9%, which declined to 79.8%, 30.7%, and 8.7% after 8, 12, and 16 weeks of WO, respectively. The percentage of patients with new T1 Gd+ lesions increased with longer WO period before commencing fingolimod: 2.1% (8 weeks), 9.1% (12 weeks), and 50.0% (16 weeks). Overall, 71% of patients with first relapse between weeks 6 and 18 had RO values below the time-matched population median. Higher T2 lesion volume (LV) at baseline predicted a higher number of new T1 Gd+ lesions. CONCLUSIONS: A faster decline in natalizumab RO, longer WO period, and higher T2 LV at baseline were associated with an increased risk for return of inflammatory disease activity. These results provide a mechanistic rationale and, together with the main outcomes of the TOFINGO study, support initiation of fingolimod within 8 weeks of natalizumab discontinuation. CLINICALTRIALSGOV IDENTIFIER: NCT01499667.

FTY720: placebo-controlled study of the effect on cardiac rate and rhythm in healthy subjects.

The purpose of this double-blind, placebo-controlled study was to measure the effects of FTY720, a novel immunomodulator, on heart rate and rhythm in healthy volunteers. Subjects (n = 66) were randomized to FTY720 1.25 mg or 5 mg or placebo administered once daily for 7 days. Continuous telemetry revealed an acute, dose-dependent decrease in mean heart rate (10-bpm decrease vs placebo) following the first dose of FTY720, with a nadir generally 4 hours postdose. Although a persistent FTY720-related decrease in heart rate was measured from day 2 to day 7, additional doses of FTY720 after day 2 resulted in no further incremental decreases. Mean PR interval increased by approximately 8 to 10 msec in FTY720-treated subjects on day 1. FTY720 did not increase the QRS or QT interval. These results confirm that the first dose of FTY720 has a mild to moderate negative chronotropic effect.

Fingolimod (FTY720) in severe hepatic impairment: pharmacokinetics and relationship to markers of liver function.

The authors assessed the impact of severe hepatic impairment on the disposition of fingolimod--a sphingosine-1-phosphate receptor immunomodulator primarily metabolized by CYP4F2--in 6 patients and 6 matched healthy controls who received a single 5-mg oral dose. Compared with healthy controls, severe hepatic-impaired subjects had a doubled area under the concentration time curve (AUC) and 50% prolonged elimination half-life but a similar peak blood concentration. When these data were combined with those from a previous study in mild and moderate hepatic-impaired subjects, there were significant positive correlations between fingolimod AUC versus bilirubin (r = 0.683) and prothrombin time (r = 0.777) and a significant negative correlation versus albumin (r = 0.578), confirming the importance of liver function for fingolimod clearance. For patients with severe hepatic impairment (Child-Pugh class C), a standard first dose of fingolimod could be given followed by a maintenance dose that is reduced by half from the normal maintenance dose.

Cyclosporine pharmacokinetics and dose monitoring after lung transplantation: comparison between cystic fibrosis and other conditions.

BACKGROUND: In cystic fibrosis (CF), absorption of cyclosporine A (CsA) through the gastrointestinal tract is often impaired because of fat malabsorption. The aim of this study was to compare the steady-state pharmacokinetics of CsA and the inter- and intrasubject variability of CsA exposure in stable lung transplant recipients with and without CF and to determine the best single-time predictors of the area under the curve (AUC). METHODS: Ten lung transplant recipients without CF and 10 lung transplant recipients with CF were studied. All patients received Neoral twice daily. Blood samples were obtained predose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, and 12 h postdose on three separate days within a 5-day period. RESULTS: CsA exposure and pharmacokinetic variables were similar in the two groups, although exposure-per-milligram-per-dose was approximately 25% lower in CF patients. Coefficients of intersubject variability were numerically higher in CF patients, but the difference between groups did not reach significance. On the other hand, the maximum concentration (Cmax), the concentration 2 hours after administration (C2), AUC0-12, and AUC0-4 showed a twofold greater intrasubject variability in CF patients. CsA trough concentration did not predict accurately the AUC, but C2 was a good predictor of the AUC0-4 in both CF (r2=0.90) and non-CF (r2=0.78) patients. CONCLUSION: Compared to patients without CF, patients with CF show a lower bioavailability of CsA and a greater intrasubject variability of Cmax, C2, and AUC. C2 is the best single-point predictor of the AUC0-4 in lung transplant recipients with and without CF.

Exposure-response relationships for everolimus in de novo kidney transplantation: defining a therapeutic range.

BACKGROUND: Exposure, safety, and efficacy data from the two everolimus randomized, double-blind phase 3 trials were evaluated to identify a therapeutic concentration range applicable in de novo kidney transplantation. METHODS: A total of 695 evaluable everolimus-treated patients received either 0.75 or 1.5 mg bid in addition to corticosteroids and cyclosporine (troughs 150-400 ng/ml in month 1 and 100-300 ng/ml thereafter). A total of 3355 everolimus trough levels (Cmin) were obtained in weeks 1 and 2 and months 1, 2, 3, and 6 after transplantation. Each patient's average Cmin was calculated and the values were divided into quintiles: 1.0-3.4, 3.5-4.5, 4.6-5.7, 5.8-7.7, 7.8-15.0 ng/ml (139 patients per quintile). Efficacy was freedom from biopsy-confirmed acute rejection. Safety measures were maximum total cholesterol and triglyceride levels and minimum leukocyte and platelet counts. A sigmoid exposure-response model was used to test the significance of these Cmin-efficacy and Cmin-safety relationships. RESULTS: Freedom from acute rejection was significantly related to Cmin with an incidence of 68% at 1.0-3.4 ng/ml, 81-86% at 3.5-7.7 ng/ml, and 91% at 7.8-15.0 ng/ml (P=0.03). The incidence of hypercholesterolemia, defined as >6.5 mmol/liter, ranged from 76 to 87% over the exposure range without a significant relation to Cmin (P=0.37). The incidence of hypertriglyceridemia, defined as >2.9 mmol/liter, rose from 59 to 77% across the exposure groups (P=0.02). Leukocytopenia, defined as <4x10(9)/liter, occurred in 11-19% of patients across the exposure quintiles showing no relationship to Cmin (P=0.76). The incidence of thrombocytopenia, defined as <100x10(9)/liter, occurred in

Everolimus in pediatric de nova renal transplant patients.

BACKGROUND: The steady-state pharmacokinetics of everolimus were longitudinally assessed in pediatric de novo kidney allograft recipients during a 6-month period. METHODS: Nineteen patients received everolimus 0.8 mg/m2 (maximum 1.5 mg) twice daily as a dispersible tablet in water in addition to cyclosporine and corticosteroids. Everolimus and cyclosporine trough concentrations were obtained on days 3, 5, 6, and 7 and at months 1, 2, 3, and 6; an everolimus pharmacokinetic profile was obtained on day 7 and month 3. RESULTS: There were 9 boys and 10 girls with a median age of 9.9 (range, 1-16) years. Steady-state pharmacokinetic parameters were as follows (median, range): C(min) (trough level), 4.7 (2.3- 9.5) ng/mL; peak concentration, 13.5 (5.9-22.2) ng/mL; area under the concentration-time curve (AUC), 77 (53-147) ng x hr/mL; and apparent oral clearance, 10.2 (5.5-15.6) L/hr/m2. Clearance (unadjusted for demographic factors) was positively correlated with age (r=0.66), body surface area (r=0.68), and weight (r=0.67). There were no trends in C(min) or AUC versus patient age when everolimus was dosed on a mg/m2 basis. Everolimus C(min) were stable over time with median values of 3.9, 3.4, and 3.1 ng/mL at months 1, 3, and 6, respectively. Intra- and interpatient variability in AUC was 29% and 35%, similar to that in adults. During the observation period, eight patients maintained stable AUCs and nine patients had increases or decreases, generally between 30% and 50% compared with the AUC at week 1. The concurrent median cyclosporine C(min) were generally at the lower end of conventional target ranges: 156, 83, and 69 ng/mL at months 1, 3, and 6, respectively. There were no graft losses and only three mild or moderate, reversible rejection episodes occurred. Everolimus was generally safe and well tolerated. CONCLUSIONS: These data support the use of body surface area-adjusted dosing for everolimus in pediatric patients. Although exposure is generally stable over time with moderate variability in AUC, therapeutic monitoring would be a helpful adjunct for individualizing everolimus exposure, assessing regimen adherence, and adjusting doses as the child matures.

A rational dosing algorithm for basiliximab (Simulect) in pediatric renal transplantation based on pharmacokinetic-dynamic evaluations.

BACKGROUND: The pharmacokinetics and immunodynamics of basiliximab were assessed in 39 pediatric de novo kidney allograft recipients to rationally chose a dose regimen for this age group. METHODS: In study part 1, patients were given 12 mg/m(2) of basiliximab by bolus intravenous injection before surgery and on day 4. An interim pharmacokinetic evaluation supported a fixed-dose approach for study part 2 in which infants and children received two 10-mg doses and adolescents received two 20-mg doses. Blood samples were collected over a 12-week period for analysis of basiliximab and soluble interleukin-2 receptor concentrations, flow cytometry, and screening for anti-idiotype antibodies. RESULTS: Basiliximab clearance in infants and children (n=25) was reduced by approximately half compared with adults from a previous study and was independent of age (1-11 years), weight (9-37 kg), and body surface area (0.44-1.20 m(2) ). Clearance in adolescents (12-16 years, n=14) approached or reached adult values. CD25-saturating basiliximab concentrations were maintained for 31+/-12 days in study part 1 with mg/m(2) dosing and for 36+/-14 days in study part 2 based on the fixed-dose regimen ( P=0.31). A single patient experienced a rejection episode during CD25 saturation. The duration of CD25 saturation in patients who experienced a rejection episode after desaturation did not differ from those who remained rejection-free for the full 6-month period: 34+/-6 days (n=6) vs. 35+/-14 days (n=33 patients); P=0.74. Anti-idiotype antibodies were detected in two patients; however, this did not influence the clearance of basiliximab or the duration of CD25 saturation. CONCLUSIONS: To achieve similar basiliximab exposure as is efficacious in adults, pediatric patients <35 kg should receive two 10-mg doses and those > or =35 kg should receive two 20-mg doses of basiliximab by intravenous infusion or bolus injection. The first dose is given before surgery and the second on day 4 after transplantation.

Everolimus in de novo cardiac transplantation: pharmacokinetics, therapeutic range, and influence on cyclosporine exposure.

We evaluated exposure, safety, and efficacy data from an international Phase 3 trial of everolimus in de novo heart transplantation to characterize the longitudinal pharmacokinetics of everolimus and cyclosporine and to identify a therapeutic concentration range for everolimus. We randomized 634 patients to receive either 0.75 mg everolimus twice daily, 1.5 mg everolimus twice daily, or azathioprine in addition to corticosteroids and cyclosporine. At 8 visits during the first 6 months after transplantation, we obtained 2,328 everolimus trough levels (Cmin) and 129 area-under-the-curve (AUC) profiles over the dosing interval in patients treated with everolimus; we collected 3,258 cyclosporine trough concentrations and 174 profiles in all 3 treatment arms. We used median-effect analysis to characterize exposure-response associations between everolimus average Cmin vs freedom from biopsy-confirmed acute rejection; maximum cholesterol, low density lipoprotein, triglyceride, and creatinine levels; and minimum leukocyte and platelet counts. Everolimus Cmins averaged 5.2 +/- 3.8 ng/ml and 9.4 +/- 6.3 ng/ml at the lower and upper dose levels. A 17% underproportionality was noted in Cmins; however, peak exposure and AUC were consistent with dose proportionality. Everolimus exposure was stable during the 6-month period. Interindividual variability was 37% for AUC and 40% for Cmin. The latter parameter was not influenced to a clinically relevant extent by sex, age, or weight. The Cmin was well correlated with AUC (r2 = 0.81). Everolimus Cmin was significantly related to freedom from rejection (p = 0.02) with 3 ng/ml being an informative lower threshold for efficacy. Thrombocytopenia, defined as <75 x 10(9)/liter, was related significantly to Cmin (p = 0.03); however, the incidence in this study was too low to establish an upper end for the therapeutic range. Lower doses of cyclosporine (by 15% to 19%) were used in patients treated with everolimus to achieve cyclosporine Cmins and AUCs similar to those in patients treated with azathioprine. Everolimus exposure was dose proportional and stable during the first 6 months after transplantation. Interindividual pharmacokinetic variability was high but not influenced by common demographic covariates. We observed a significantly increased risk of acute rejection at everolimus trough levels <3 ng/ml, which constitutes the lower therapeutic concentration limit when everolimus is used with conventionally dosed cyclosporine. Everolimus-related adverse events were manageable up to the highest troughs (22 ng/ml) observed in this population. We could not derive a precise upper therapeutic concentration limit from these data.

Multiple-dose FTY720: tolerability, pharmacokinetics, and lymphocyte responses in healthy subjects.

FTY720 is a sphingosine-1-phosphate receptor agonist being developed as an immunomodulator for acute rejection prophylaxis after organ transplantation. This study was performed to characterize the pharmacokinetics of and lymphocyte response to multiple-dose FTY720. In this randomized, double-blind study, three groups of 20 healthy subjects each received either placebo, 1.25 mg/day FTY720, or 5 mg/day FTY720 for 7 consecutive days. FTY720 blood concentrations and lymphocyte counts were assessed over the weeklong treatment phase and over a month-long washout phase. The relationship between FTY720 blood concentrations and lymphocyte counts was explored by an inhibitory E(max) model. First-dose exposure was consistent with dose proportionality between the low- and high-dose groups. Blood levels accumulated fivefold over the treatment period. Exposure on day 7 was dose proportional for C(max) (5.0 +/- 1.0 vs. 18.2 +/- 4.1 ng/mL) and for AUC (109 +/- 24 vs. 399 +/- 85 ng.h/mL). Washout pharmacokinetics after the last dose indicated an elimination half-life averaging 8 days. Lymphocyte counts decreased by 80% in subjects receiving the lower dose to a nadir of 0.4 +/- 0.1 x 10(9)/L and by 88% in subjects receiving the upper dose to a nadir of 0.2 +/- 0.1 x 10(9)/L. Descriptive exposure-response modeling estimated that the lymphocyte response at 5 mg/day is near the maximal response achievable. By the end-of-study evaluation on day 35, lymphocyte counts had recovered to within 75% and 50% of baseline in the low- and high-dose groups, respectively. In summary, systemic exposure to FTY720 was consistent with dose-proportionality after both single- and multiple-dose administration. Total lymphocyte counts decreased from baseline by 80% and 88% at regimens of 1.25 and 5 mg/day, respectively. Exposure-response modeling provided evidence that 5 mg/day FTY720 resulted in a near-maximal dynamic effect of this drug on lymphocytes.

Differential influence of two cyclosporine formulations on everolimus pharmacokinetics: a clinically relevant pharmacokinetic interaction.

Everolimus is an immunosuppressant intended for use with cyclosporine in acute-rejection prophylaxis following organ transplantation. The possibility of a drug interaction of cyclosporine on everolimus was assessed. In this randomized, two-period, crossover study, 24 healthy subjects received a single oral dose of 2 mg everolimus alone and with one of two cyclosporine formulations: either 175 mg Neoral or 300 mg Sandimmune. The single doses of Neoral and Sandimmune were chosen to yield similar average areas under the concentration-time curve (AUC). Treatments were separated by a 14-day washout period. Cyclosporine AUCs were similar for both formulations (p = 0.53), whereas the peak concentration (Cmax) was significantly higher for Neoral (p = 0.02). Simultaneous administration of Neoral with everolimus increased everolimus Cmax and AUC by 82% and 168%, respectively (p = 0.0001). Coadministration of Sandimmune with everolimus did not affect everolimus Cmax (p = 0.59) but increased everolimus AUC by 74% on average (p = 0.0001). Everolimus elimination half-lives were unchanged in the presence of both cyclosporine formulations. The everolimus AUC increase with Neoral coadministration was significantly greater than the AUC increase with Sandimmune (p = 0.008). However, there was no apparent association between cyclosporine Cmax and the change in everolimus AUC with cyclosporine coadministration. If Neoral or Sandimmune is removed from an everolimus-cyclosporine immunosuppressive regimen, a two- to three-fold decrease in everolimus exposure is expected. Therapeutic monitoring of everolimus concentrations would be helpful after the removal of cyclosporine to individually titrate everolimus exposure.