Population Pharmacokinetics of Nirsevimab in Preterm and Term Infants.

Nirsevimab, a monoclonal antibody with an extended half-life, is approved for the prevention of respiratory syncytial virus (RSV) disease in all infants in Canada, the EU, Great Britain, and the USA. A population pharmacokinetics (PK) model was built to describe the PK of nirsevimab in preterm and term infants, and to evaluate the influence of covariates, including body weight and age, in infants. Nirsevimab PK was characterized by a 2-compartment model with first-order clearance (CL) and first-order absorption following intramuscular (IM) administration. The typical CL in a 5 kg infant was 3.4 mL/day. Body weight and postmenstrual age were the primary covariates on CL, with minor effects for race, second RSV season, and antidrug antibody status (deemed not clinically relevant). Congenital heart disease (CHD) and chronic lung disease (CLD) did not significantly impact nirsevimab PK. The final population PK model, based on 8987 PK observations from 2683 participants across 5 clinical trials, successfully predicted PK in an additional cohort of 967 healthy infants. Weight-banded dosing (50 mg in infants <5 kg; 100 mg in infants ≥5 kg) was predicted to be appropriate for infants ≥1 kg in their first RSV season. Together, these data support weight-banded dosing of nirsevimab in all infants in their first RSV season, including in healthy infants, infants with CHD or CLD, and in infants born prematurely.

Molecular and phenotypic characteristics of RSV infections in infants during two nirsevimab randomized clinical trials.

Nirsevimab is a monoclonal antibody that binds to the respiratory syncytial virus (RSV) fusion protein. During the Phase 2b (NCT02878330) and MELODY (NCT03979313) clinical trials, infants received one dose of nirsevimab or placebo before their first RSV season. In this pre-specified analysis, isolates from RSV infections were subtyped, sequenced and analyzed for nirsevimab binding site substitutions; subsequently, recombinant RSVs were engineered for microneutralization susceptibility testing. Here we show that the frequency of infections caused by subtypes A and B is similar across and within the two trials. In addition, RSV A had one and RSV B had 10 fusion protein substitutions occurring at >5% frequency. Notably, RSV B binding site substitutions were rare, except for the highly prevalent I206M:Q209R, which increases nirsevimab susceptibility; RSV B isolates from two participants had binding site substitutions that reduce nirsevimab susceptibility. Overall, >99% of isolates from the Phase 2b and MELODY trials retained susceptibility to nirsevimab.

Efficacy and safety of AZD7594, an inhaled non-steroidal selective glucocorticoid receptor modulator, in patients with asthma: a phase 2a randomized, double blind, placebo-controlled crossover trial.

BACKGROUND: Inhaled corticosteroids reduce inflammation in asthma but chronic use may cause adverse effects. AZD7594, an inhaled non-steroidal selective glucocorticoid receptor modulator, has the potential of an improved risk-benefit profile. We investigated the safety and efficacy of AZD7594 in asthma. METHODS: This phase 2a multi-center, randomized, double-blind, placebo-controlled crossover study enrolled adults with asthma aged 18 to 75 years. Patients were treated with budesonide 200 µg twice daily for 2-3 3 weeks (run in part one). If controlled, as demonstrated by an asthma control questionnaire-5 score of < 1.5, patients entered a three-week run-in (part two) where they received a short acting bronchodilator alone. Thereafter, patients with a fractional exhaled nitric oxide (FENO) ≥25 ppb and pre-dose FEV1 40 to 90% predicted were randomized to one of nine treatment sequences. Each patient received placebo and two of three dose levels of AZD7594 (58, 250, 800 µg) once daily via inhalation, in 14-day treatment periods, separated by three-week washout periods. The primary endpoint was the change from baseline in morning trough FEV1 versus placebo on day 15. Secondary endpoints included measures of airway inflammation and asthma control. RESULTS: Fifty-four patients were randomized and received at least 1 dose of treatment, 48 patients completed the study. Overall 52 patients received placebo, 34 received AZD7594 58 µg, 34 received AZD7594 250 µg, and 34 received AZD7594 800 µg. AZD7594 800 µg demonstrated a significant improvement in Day 15 morning trough FEV1versus placebo (LS means difference 0.148 L 95% CI 0.035-0.261, p = 0.011), with a dose-dependent response seen in the 250 µg (0.076 L -0·036-0·188, p = 0.183) and 58 µg (0·027 L -0·086-0·140, p = 0.683). All secondary endpoints showed statistically significant improvement at the 800 µg dose. All doses demonstrated a significant reduction in FENO at day 15 p < 0.01. No statistically significant difference in plasma cortisol level was observed between AZD7594 and placebo at any dose. AZD7594 was considered safe and well tolerated. CONCLUSIONS: Two-week treatment with AZD7594 demonstrated a favorable risk-benefit profile in patients with mild to moderate asthma. Further clinical studies are needed to fully characterize AZD7594. TRIAL REGISTRATION: ClinicalTrials.gov number NCT02479412 .

Pharmacokinetics of the Inhaled Selective Glucocorticoid Receptor Modulator AZD5423 Following Inhalation Using Different Devices.

AZD5423 is a non-steroidal glucocorticoid receptor modulator, with low aqueous solubility, developed for treatment of asthma and COPD. In this work, we aim to evaluate and compare the absorption pharmacokinetics (PK) of AZD5423 after inhalation via four devices, (Spira®, I-neb®, Turbuhaler® and a new dry powder inhaler (new DPI)) with two formulations using differently sized primary particles, and to compare the pulmonary bioavailability with the predicted lung deposited dose. Plasma concentration-time data after intravenous, oral and inhaled administration via four devices were available from two clinical studies in healthy and asthmatic subjects. A population PK modelling approach was taken to sequentially incorporate each route of administration, assuming parallel absorption compartments for inhaled AZD5423. A non-compartmental analysis for derivation of PK parameters was performed for comparison. Pulmonary bioavailability varied between devices, with the lowest estimates for I-neb (27%) and Turbuhaler (30%) and the highest for the new DPI (46%) and Spira (35-49%). The pulmonary bioavailability was substantially lower than the predicted lung deposited dose (range 59-90%). Lung absorption was separated into a faster and a slower process in the model. The half-life of the faster absorption appeared formulation-dependent, while the slower absorption (half-life of 0.59-0.78 h) appeared independent of formulation. The large difference in the estimated pulmonary bioavailability and the predicted lung deposited dose for AZD5423 implies an impact of mucociliary clearance. The lung absorption half-life indicates that AZD5423 is retained in the lung for a relatively short time.

Pharmacokinetic-pharmacodynamic modeling of fostamatinib efficacy on ACR20 to support dose selection in patients with rheumatoid arthritis (RA).

R788 (fostamatinib) is an oral prodrug that is rapidly converted into a relatively selective spleen tyrosine kinase (SYK) inhibitor R406, evaluated for the treatment of rheumatoid arthritis (RA). This analysis aimed at developing a pharmacodynamic model for efficacy using pooled ACR20 data from two phase II studies in patients with rheumatoid arthritis (TASKi1 and TASKi2), describing the effect of fostamatinib as a function of fostamatinib exposure (dose, R406 plasma concentration) and other explanatory variables. The exposure-response relationship of fostamatinib was implemented into a continuous time Markov model describing the time course of transition probabilities between the three possible states of ACR20 non-responder, responder, and dropout at each visit. The probability of transition to the ACR20 response state was linearly (at the rate constant level) related to average R406 plasma concentrations and the onset of this drug effect was fast. Further, increases of fostamatinib dose resulted in increased dropout and subsequent loss of efficacy. This analysis provided an increased understanding of the exposure-response relationship, and provided support for fostamatinib 100 mg BID an appropriate dose regimen for further clinical evaluation.