Efficacy and safety of brodalumab, an anti-IL17RA monoclonal antibody, in patients with axial spondyloarthritis: 16-week results from a randomised, placebo-controlled, phase 3 trial.

OBJECTIVE: To investigate the efficacy and safety of brodalumab, a fully human anti-interleukin-17 receptor A monoclonal antibody, in patients with axial spondyloarthritis (axSpA). METHODS: In a multicentre, placebo-controlled phase 3 study (NCT02985983) conducted at 48 sites across Japan, Korea and Taiwan, patients with axSpA were randomised 1:1 to receive subcutaneous brodalumab 210 mg (n=80) or placebo (n=79) at baseline, weeks 1 and 2 and every 2 weeks thereafter, during the 16-week double-blind period. The primary endpoint was the proportion of patients with Assessment of SpondyloArthritis International Society (ASAS) 40 response at week 16. Secondary endpoints included the proportion of patients with ASAS 20 response and change in Ankylosing Spondylitis Disease Activity Score using C-reactive protein (ASDAS-CRP) at week 16 and safety. RESULTS: ASAS 40 response rate (n/N; 95% CI) was 43.8% (35/80; 32.7, 55.3) with brodalumab vs 24.1% (19/79; 15.1, 35.0) with placebo (rate difference, 19.7% (5.3, 34.1); p=0.018 by stratified Cochran-Mantel-Haenszel test). ASAS 20 response rate (n/N; 95% CI) was 67.5% (54/80; 56.1, 77.6) vs 41.8% (33/79; 30.8, 53.4) and least squares mean change (95% CI) from baseline (brodalumab, 2.660; placebo, 2.716) in ASDAS-CRP was -1.127 (-1.322, -0.931) with brodalumab vs -0.672 (-0.872, -0.473) with placebo at week 16. Treatment-emergent adverse events were reported in 44 (55%) and 45 (57%) patients in the brodalumab and placebo groups, respectively. CONCLUSION: Brodalumab demonstrated a significant improvement at week 16 in patients with active axSpA. Safety of brodalumab was consistent with that reported in previous global/Japanese psoriasis studies.

Influence of the cytochrome P450 2D6 *10/*10 genotype on the pharmacokinetics of paroxetine in Japanese patients with major depressive disorder: a population pharmacokinetic analysis.

OBJECTIVE: Although the reduced function of the cytochrome P450 2D6*10 (CYP2D6*10) allele is common among Asian populations, existing evidence does not support paroxetine therapy adjustments for patients who have the CYP2D6*10 allele. In this study, we attempted to evaluate the degree of the impact of different CYP2D6 genotypes on the pharmacokinetic (PK) variability of paroxetine in a Japanese population using a population PK approach. METHODS: This retrospective study included 179 Japanese patients with major depressive disorder who were being treated with paroxetine. CYP2D6*1, *2, *5, *10, and *41 polymorphisms were observed. A total of 306 steady-state concentrations for paroxetine were collected from the patients. A nonlinear mixed-effects model identified the apparent Michaelis-Menten constant (Km) and the maximum velocity (Vmax) of paroxetine; the covariates included CYP2D6 genotypes, patient age, body weight, sex, and daily paroxetine dose. RESULTS: The allele frequencies of CYP2D6*1, *2, *5, *10, and *41 were 39.4, 14.5, 4.5, 41.1, and 0.6%, respectively. There was no poor metabolizer who had two nonfunctional CYP2D6*5 alleles. A one-compartment model showed that the apparent Km value was decreased by 20.6% in patients with the CYP2D6*10/*10 genotype in comparison with the other CYP2D6 genotypes. Female sex also influenced the apparent Km values. No PK parameters were affected by the presence of one CYP2D6*5 allele. CONCLUSION: Unexpectedly, elimination was accelerated in individuals with the CYP2D6*10/*10 genotype. Our results show that the presence of one CYP2D6*5 allele or that of any CYP2D6*10 allele may have no major effect on paroxetine PKs in the steady state.

Pregnane X receptor and hepatocyte nuclear factor 4α polymorphisms are cooperatively associated with carbamazepine autoinduction.

OBJECTIVE: We attempted to clarify the influence of polymorphisms of nuclear receptors on carbamazepine therapy. PARTICIPANTS AND METHODS: The common polymorphisms of nuclear receptors--a tentative pregnane X receptor (PXR)*1B, hepatocyte nuclear factor 4α (HNF4α) rs2071197 (c.115+308G>A), and cytochrome P450 3A5*3 polymorphisms--were genotyped in 168 Japanese patients with epilepsy. The associations of these polymorphisms with the disposition, clinical efficacy, and incidence of adverse effects of carbamazepine treatment were retrospectively investigated in 104 patients treated with carbamazepine alone. The associations with disposition were also assessed in 64 patients treated with carbamazepine and other antiepileptic drugs, which constituted the internal replication group, and in the combined 168 patients. RESULTS: Neither polymorphism alone affected the carbamazepine disposition, but a significant interactive effect of PXR*1B and HNF4α rs2071197 polymorphisms on the concentration-to-dose (C/D) ratios was observed (P=0.027). The C/D ratios among patients with the HNF4α G/G genotype were higher in PXR*1B carriers than in PXR*1B noncarriers, which was confirmed in the internal replication and combined groups. In patients with the HNF4α G/G genotype, the rate of freedom from seizures until 3 months after starting carbamazepine therapy was significantly greater and the time required to reach the dose required for seizure freedom was shorter in PXR*1B carriers than in PXR*1B noncarriers. CONCLUSION: These results suggest that PXR*1B, in combination with HNF4α rs2071197, might be associated with the C/D ratios and the duration to reach the maintenance dose of carbamazepine therapy, thus indicating an influence upon the autoinduction of the carbamazepine metabolism.

Effects of CYP2C19 and P450 oxidoreductase polymorphisms on the population pharmacokinetics of clobazam and N-desmethylclobazam in japanese patients with epilepsy.

BACKGROUND: Clobazam (CLB) is a 1,5-benzodiazepine with antiepileptic properties. More than 70% of administered CLB is dealkylated to yield N-desmethylclobazam (N-CLB), a pharmacologically active metabolite, by cytochrome P450 (CYP) 3A4 and CYP2C19. The subsequent inactivation of N-CLB is primarily catalyzed by CYP2C19. Meanwhile, P450 oxidoreductase (POR) is the obligatory electron donor to all microsomal CYP enzymes. The aim of this study was to evaluate the impact of the CYP2C19 and POR genotypes on the pharmacokinetic parameters of CLB and N-CLB. METHODS: This retrospective study included 85 Japanese patients with epilepsy who were treated with CLB. CYP2C19*2, *3, and P450 oxidoreductase (POR) *28 (rs1057868C>T) polymorphisms were evaluated. A total of 128 steady-state concentrations for both CLB and N-CLB were collected from the patients. A nonlinear mixed-effects model identified the pharmacokinetics of CLB and N-CLB; the covariates included CYP2C19 and POR genotypes, weight, gender, daily CLB dose, and coadministered antiepileptic drugs. RESULTS: Among the 85 patients, the allele frequencies of CYP2C19*2, CYP2C19*3, and POR*28 were 27.6%, 12.9%, and 41.2%, respectively. A one-compartment model with first-order absorption and/or elimination showed that the clearance of CLB and N-CLB was significantly lower by 18.1% and 84.9%, respectively, in the CYP2C19 poor metabolizers compared with the homozygous extensive metabolizers. The CLB clearance was 44% higher in subjects homozygous for the POR*28 T allele than in those homozygous for the POR*28 C allele, although the genotypes did not affect the N-CLB clearance. The concomitant use of phenobarbital, phenytoin, and zonisamide significantly affected the CLB clearance, whereas that of carbamazepine, phenytoin, and valproic acid affected the N-CLB clearance. The weight also significantly influenced the CLB clearance and volume of distribution of both CLB and N-CLB. CONCLUSIONS: Our results showed that the CYP2C19 and/or POR genotypes have an impact on the CLB and/or N-CLB clearance. These results suggest that determining the CYP2C19 and/or POR genotypes is helpful for obtaining appropriate serum CLB and N-CLB concentrations and preventing an overdose when starting CLB therapy.

Possible association between moderate intellectual disability and weight gain in valproic acid-treated patients with epilepsy.

BACKGROUND: Although patients with moderate intellectual disability (ID) are known to have higher rates of being overweight and obese than those without ID, there are no current data regarding the relationship between ID and weight gain in epilepsy patients treated with valproic acid (VPA). PATIENTS AND METHODS: The possible association between moderate ID and an overweight status at the time of initiation of VPA therapy (baseline) was investigated using a logistic regression analysis in 143 patients with epilepsy. Among the 119 nonoverweight patients at baseline, the longitudinal association between moderate ID and the weight status during VPA therapy was retrospectively examined using a Cox hazards regression analysis and the generalized estimating equations approach, while also paying careful attention to associations with other patient characteristics. RESULTS: The proportion of patients with moderate ID was 52.4% among the 143 study subjects. The presence of moderate ID was not associated with an overweight status at baseline (P=0.762). Among the nonoverweight patients at baseline, 16 subjects were newly diagnosed as being overweight during treatment with VPA (3.6±2.1 years). The presence of moderate ID was significantly associated with the incidence of an overweight status after starting VPA therapy (adjusted hazard ratio =6.72, P=0.007). The patient age at baseline and treatment with co-administered carbamazepine, clobazam, and zonisamide significantly influenced the degree of weight fluctuation during VPA therapy among the patients with moderate ID (P<0.001, P<0.001, P=0.002, and P=0.028, respectively), whereas only patient age at baseline affected this parameter among the patients without moderate ID (P=0.022). CONCLUSION: The present findings suggest that the weight status should be carefully monitored in VPA-treated patients with moderate ID, especially those receiving other co-administered antiepileptic drugs that facilitate weight gain, such as carbamazepine.

Determination of the Optimal Concentration of Valproic Acid in Patients with Epilepsy: A Population Pharmacokinetic-Pharmacodynamic Analysis.

Valproic acid (VPA) is one of the most widely prescribed antiepileptic drugs for the treatment of epileptic seizures. Although it is well known that the doses of VPA and its plasma concentrations are highly correlated, the plasma concentrations do not correlate well with the therapeutic effects of the VPA. In this study, we developed a population-based pharmacokinetic (PK)-pharmacodynamic (PD) model to determine the optimal concentration of VPA according to the clinical characteristics of each patient. This retrospective study included 77 VPA-treated Japanese patients with epilepsy. A nonlinear mixed-effects model best represented the relationship between the trough concentrations of VPA at steady-state and an over 50% reduction in seizure frequency. The model was fitted using a logistic regression model, in which the logit function of the probability was a linear function of the predicted trough concentration of VPA. The model showed that the age, seizure locus, the sodium channel neuronal type I alpha subunit rs3812718 polymorphism and co-administration of carbamazepine, clonazepam, phenytoin or topiramate were associated with an over 50% reduction in the seizure frequency. We plotted the receiver operating characteristic (ROC) curve for the logit(Pr) value of the model and the presence or absence of a more than 50% reduction in seizure frequency, and the areas under the curves with the 95% confidence interval from the ROC curve were 0.823 with 0.793-0.853. A logit(Pr) value of 0.1 was considered the optimal cut-off point (sensitivity = 71.8% and specificity = 80.4%), and we calculated the optimal trough concentration of VPA for each patient. Such parameters may be useful to determine the recommended therapeutic concentration of VPA for each patient, and the procedure may contribute to the further development of personalized pharmacological therapy for epilepsy.

Possible impact of the CYP2D6*10 polymorphism on the nonlinear pharmacokinetic parameter estimates of paroxetine in Japanese patients with major depressive disorders.

It has been suggested that the reduced function allele with reduced cytochrome P450 (CYP) 2D6 activity, CYP2D6*10, is associated with the interindividual differences in the plasma paroxetine concentrations, but there is no data presently available regarding the influence of the CYP2D6*10 polymorphism on the pharmacokinetic parameters, eg, Michaelis-Menten constant (Km) and maximum velocity (Vmax), in Asian populations. The present study investigated the effects of the CYP2D6 polymorphisms, including CYP2D6*10, on the pharmacokinetic parameters of paroxetine in Japanese patients with major depressive disorders. This retrospective study included 15 Japanese patients with major depressive disorders (four males and eleven females) who were treated with paroxetine. The CYP2D6*2, CYP2D6*4, CYP2D6*5, CYP2D6*10, CYP2D6*18, CYP2D6*39, and CYP2D6*41 polymorphisms were evaluated. A total of 56 blood samples were collected from the patients. The Km and Vmax values of paroxetine were estimated for each patient. The allele frequencies of CYP2D6*2, CYP2D6*4, CYP2D6*5, CYP2D6*10, CYP2D6*18, CYP2D6*39, and CYP2D6*41 were 6.7%, 0%, 10.0%, 56.7%, 0%, 26.7%, and 0%, respectively. The mean values of Km and Vmax were 50.5±68.4 ng/mL and 50.6±18.8 mg/day, respectively. Both the Km and Vmax values were significantly smaller in CYP2D6*10 allele carriers than in the noncarriers (24.2±18.3 ng/mL versus 122.5±106.3 ng/mL, P=0.008; 44.2±16.1 mg/day versus 68.3±15.0 mg/day, P=0.022, respectively). This is the first study to demonstrate that the CYP2D6*10 polymorphism could affect the nonlinear pharmacokinetic parameter estimates of paroxetine in Asian populations. The findings of this study suggest that the CYP2D6*10 polymorphism may be associated with the smaller values of both the Km and Vmax in Japanese patients with major depressive disorders, and these results need to be confirmed in further investigations with a larger number of patients.

Impact of the superoxide dismutase 2 Val16Ala polymorphism on the relationship between valproic acid exposure and elevation of γ-glutamyltransferase in patients with epilepsy: a population pharmacokinetic-pharmacodynamic analysis.

BACKGROUND: There has been accumulating evidence that there are associations among γ-glutamyltransferase (γ-GT) elevation and all-cause mortality, cardiovascular diseases and metabolic diseases, including nonalcoholic fatty liver disease. The primary objective of this study was to evaluate the impact of the most common and potentially functional polymorphisms of antioxidant enzyme genes, i.e. superoxide dismutase 2 (SOD2), glutathione S-transferase M1 and glutathione S-transferase T1, on the γ-GT elevation during valproic acid (VPA) therapy. METHODS AND FINDINGS: This retrospective study included 237 and 169 VPA-treated Japanese patients with epilepsy for population pharmacokinetic and pharmacokinetic-pharmacodynamic analyses, respectively. A nonlinear mixed-effect model represented the pharmacokinetics of VPA and the relationships between VPA exposure and γ-GT elevation. A one-compartment model of the pharmacokinetic parameters of VPA adequately described the data; while the model for the probability of the γ-GT elevation was fitted using a logistic regression model, in which the logit function of the probability was a linear function of VPA exposure. The SOD2 Val16Ala polymorphism and complication with intellectual disability were found to be significant covariates influencing the intercept of the logit function for the probability of an elevated γ-GT level. The predicted mean percentages of the subjects with γ-GT elevation were about 2- to 3-fold, 3- to 4-fold and 4- to 8-fold greater in patients with the SOD2 Val/Val genotype but without any intellectual disability, those with the SOD2 Val/Ala or Ala/Ala genotype and intellectual disability and those with the SOD2 Val/Val genotype and intellectual disability, respectively, compared to those with the SOD2 Val/Ala or Ala/Ala genotype without intellectual disability. CONCLUSION: Our results showed that the SOD2 Val16Ala polymorphism has an impact on the relationship between VPA exposure and γ-GT elevation in patients with epilepsy. These results suggest that determining the SOD2 genotype could be helpful for preventing the VPA-induced γ-GT elevation.

Superoxide dismutase 2 Val16Ala polymorphism is a risk factor for the valproic acid-related elevation of serum aminotransferases.

The association between the superoxide dismutase 2 (SOD2) Val16Ala polymorphism and the serum aminotransferase levels was retrospectively investigated in 207 valproic acid-treated patients with epilepsy. The Val/Val genotype tended to show elevated alanine aminotransferase levels (odds ratio=3.5; P=0.056). In addition, an elevated γ-glutamyltransferase level was associated with the Val/Val genotype (odds ratio=3.1; P=0.022). The SOD2 Val/Val genotype may therefore contribute to a valproic acid-induced elevation in the serum aminotransferase levels.