Population Pharmacokinetics of Tralokinumab in Adult Subjects With Moderate to Severe Atopic Dermatitis.

Tralokinumab is the first biologic therapy for moderate-to-severe atopic dermatitis (AD) that specifically neutralizes interleukin-13 activity, a key driver of AD signs and symptoms. Tralokinumab is a human immunoglobulin G4 monoclonal antibody administered subcutaneously every 2 weeks (with possibility of maintenance dosing every 4 weeks). This population pharmacokinetic (PK) analysis aimed to identify sources of PK variability and relevant predictors of tralokinumab exposure in adults with moderate to severe AD. Nonlinear mixed-effect modeling, including covariate analysis, was used on a data set including 2561 subjects (AD, asthma, healthy) from 10 clinical trials. A 2-compartment model with first-order absorption and elimination adequately described the tralokinumab PK. Body weight was identified as a relevant predictor of tralokinumab exposure; other covariates including age, sex, race, ethnicity, disease type, AD severity, and renal and hepatic impairment were not. For body weight, the difference in exposure between the upper- and lower-weight quartiles in patients with AD was <2-fold, supporting the appropriateness of flat dosing (300 mg). Given the reduced exposure associated with higher body weight, coupled with the reduced exposure provided by dosing every 4 weeks, it is uncertain whether higher-weight patients will achieve sufficient exposure to maintain efficacy if dosed every 4 weeks instead of the standard every 2 weeks.

Population pharmacokinetics of brodalumab in patients with moderate to severe plaque psoriasis.

Brodalumab is a fully human monoclonal antibody targeting the IL-17 receptor A leading to an inhibition of the biological effect of IL-17A, IL-17F, IL-17A/F heterodimer, IL-17C and IL-17E isoforms. It has shown to be efficacious in the treatment of moderate to severe plaque psoriasis (210 mg administered subcutaneously at weeks 0, 1 and 2 followed by 210 mg every 2 weeks [Q2W+1]). A population pharmacokinetic model based on psoriasis patients only from six clinical trials was developed to describe the pharmacokinetics and identify sources of variability. In patients with psoriasis, Brodalumab exhibits non-linear pharmacokinetics due to target-mediated drug disposition resulting in concentration-dependent clearance. The pharmacokinetics was best described by a two-compartment model with linear absorption and combined linear and Michaelis-Menten elimination. The subcutaneous bioavailability of Brodalumab was 55%, absorption rate was 0.30 day-1 , and body-weight was found to affect the volume of distribution and clearance. For a reference patient with plaque psoriasis (body-weight of 90 kg), the estimates were 0.16 L/d for linear serum clearance, 6.1 mg/d for the maximum non-linear clearance rate, and 4.7 and 2.4 L for central and peripheral volume of distribution, respectively. For the approved dosing regimen, time to maximum concentration was 4 days and 90% of steady-state was achieved after 10 weeks for a reference patient. Following last dose at steady-state, 90% of the population of reference patients will reach serum concentrations below lower limit of quantification after 45 days.

Patient-specific modeling of the neuroendocrine HPA-axis and its relation to depression: Ultradian and circadian oscillations.

In the Western world approximately 10% of the population experience severe depression at least once in their lifetime and many more experience a mild form of depression. Depression has been associated with malfunctions in the hypothalamus-pituitary-adrenal (HPA) axis. We suggest a novel mechanistic non-linear model capable of showing both circadian as well as ultradian oscillations of the hormone concentrations related to the HPA-axis. The fast ultradian rhythm is assumed to originate from the hippocampus whereas the slower circadian rhythm is assumed to be caused by the circadian clock. The model is able to describe the oscillatory patterns in hormone concentration data from 29 patients and healthy controls. Using non-linear mixed effects modeling with statistical hypothesis testing, three of the model parameters are identified to be related to depression. These parameters represent underlying physiological mechanisms controlling the average levels as well as the ultradian frequencies and amplitudes of the hormones ACTH and cortisol. The results are promising since they point toward an exact etiology for depression. As a consequence new biomarkers and pharmaceutical targets may be identified.

Discovery and development of 11C-Lu AE92686 as a radioligand for PET imaging of phosphodiesterase10A in the brain.

UNLABELLED: Phosphodiesterase 10A (PDE10A) plays a key role in the regulation of brain striatal signaling, and several pharmaceutical companies currently investigate PDE10A inhibitors in clinical trials for various central nervous system diseases. A PDE10A PET ligand may provide evidence that a clinical drug candidate reaches and binds to the target. Here we describe the successful discovery and initial validation of the novel radiolabeled PDE10A ligand 5,8-dimethyl-2-[2-((1-(11)C-methyl)-4-phenyl-1H-imidazol-2-yl)-ethyl]-[1,2,4]triazolo[1,5-a]pyridine ((11)C-Lu AE92686) and its tritiated analog (3)H-Lu AE92686. METHODS: Initial in vitro experiments suggested Lu AE92686 as a promising radioligand, and the corresponding tritiated and (11)C-labeled compounds were synthesized. (3)H-Lu AE92686 was evaluated as a ligand for in vivo occupancy studies in mice and rats, and (11)C-Lu AE92686 was evaluated as a PET tracer candidate in cynomolgus monkeys and in humans. RESULTS: (11)C-Lu AE92686 displayed high specificity and selectivity for PDE10A-expressing regions in the brain of cynomolgus monkeys and humans. Similar results were found in rodents using (3)H-Lu AE92686. The binding of (11)C-Lu AE92686 and (3)H-Lu AE92686 to striatum was completely and dose-dependently blocked by the structurally different PDE10A inhibitor 2-[4-(1-methyl-4-pyridin-4-yl-1H-pyrazol-3-yl)-phenoxymethyl]-quinoline (MP-10) in rodents and in monkeys. In all species, specific binding of the radioligand was seen in the striatum but not in the cerebellum, supporting the use of the cerebellum as a reference region. The binding potentials (BPND) of (11)C-Lu AE92686 in the striatum of both cynomolgus monkeys and humans were evaluated by the simplified reference tissue model with the cerebellum as the reference tissue, and BPND was found to be high and reproducible-that is, BPNDs were 6.5 ± 0.3 (n = 3) and 7.5 ± 1.0 (n = 12) in monkeys and humans, respectively. CONCLUSION: Rodent, monkey, and human tests of labeled Lu AE92686 suggest that (11)C-Lu AE92686 has great potential as a human PET tracer for the PDE10A enzyme.