Introduction

Augmentation therapy with plasma-derived α₁-proteinase inhibitor (A1PI) products is currently the only approved disease-specific therapy for α₁-antitrypsin deficiency (AATD), a genetic disorder associated with decreased levels of A1PI. Systemic trough levels of A1PI in plasma or serum are widely accepted as a biochemical efficacy endpoint in clinical trials for A1PI products.

Methods

Retrospective analyses utilizing data from three clinical studies in patients with AATD were conducted to evaluate the pharmacokinetic(s) (PK) and biochemical efficacy comparability of Aralast NP and two other A1PI augmentation therapies, Aralast and Prolastin. All three A1PI products were administered as either single or multiple 60 mg/kg intravenous infusions. PK and biochemical efficacy comparability analyses were conducted by evaluating antigenic and functional A1PI serum or plasma concentration data from each of the three studies.

Results

Comparable PK parameters were demonstrated between the three products for antigenic A1PI levels following a single infusion, with baseline-corrected and uncorrected geometric mean ratios for peak and systemic exposure ranging from 89.0% to 99.6%, with 90% confidence intervals within the 80-125% reference interval for bioequivalence. Biochemical efficacy comparability analyses of Aralast and Prolastin after multiple infusions at steady state showed geometric mean ratios for uncorrected and baseline-corrected antigenic and functional A1PI trough concentrations over weeks 8-11, and for individual weeks, that ranged from 75.8% to 106.6%, with the majority of the 90% confidence intervals falling either within the 80-125% interval or in proximity to it. Nonparametric superpositioning at steady state suggested that predicted trough concentrations for Aralast NP were comparable to the observed concentrations for Aralast and Prolastin.

Conclusion

These retrospective analyses provide robust evidence that Aralast NP has biochemical efficacy and PK comparable to that of Aralast and Prolastin, supporting the use of any of these A1PI products for the treatment of patients with AATD.

Trial registration numbers

ClinicalTrials.gov identifiers, NCT00242385 and NCT00396006.

OBJECTIVE: Multifocal motor neuropathy is a rare chronic immune-mediated neuropathy with impaired grip strength representing a common symptom. While intravenous immunoglobulin G is an effective treatment for the disease, significant variation in treatment response has been observed but not well understood. This analysis characterized dose-exposure-response relationships in multifocal motor neuropathy, using grip strength as a clinical efficacy measure. METHODS: Serum immunoglobulin G trough concentrations and grip strength data for the more affected hand from a Phase 3, randomized, double-blind, placebo-controlled, crossover trial of intravenous immunoglobulin 10% in 44 patients with multifocal motor neuropathy (NCT00666263) were used to develop a population pharmacokinetic-pharmacodynamic model. RESULTS: The model adequately described the observed pharmacokinetic and pharmacodynamic data and relationships between intravenous immunoglobulin 10% dose, serum immunoglobulin G trough levels, grip strength, and inter-patient variabilities in multifocal motor neuropathy. Model-based simulations for various dosing regimens (0.4-2.0 g/kg every 2-4 weeks) indicated that ≥1.6 g/kg/month would achieve clinically meaningful improvements in grip strength (≥4 kg) in ≥70% of patients. More frequent dosing at an equivalent monthly dose led to a more consistent response in grip strength. Furthermore, splitting the dose over multiple days for high doses (>1 g/kg) did not impact grip strength. INTERPRETATION: These findings suggest that the majority of patients with multifocal motor neuropathy would respond rapidly to intravenous immunoglobulin 10% with a range of dosing regimens. Shorter dosing intervals may avoid the diminishing response seen with longer dosing intervals. Dose-splitting provided similar outcomes while offering flexibility and convenience.

INTRODUCTION: Intravenous immunoglobulin (IVIG) is the only approved treatment for multifocal motor neuropathy (MMN), a rare, chronic, immune-mediated demyelinating neuropathy. There is a significant gap in understanding of the role of serum immunoglobulin G (IgG) levels in the efficacy of IVIG in affected patients. We aimed to characterize the interplay between dose and exposure of IVIG and the effects of patient factors on individual variabilities. METHODS: Serum IgG trough concentration data from a phase 3, randomized, double-blind, placebo-controlled, crossover trial of IVIG 10% in 44 patients with MMN (NCT00666263) were analyzed using fit-for-purpose population PK modeling. Patient factors were tested as covariates, and IgG PK profiles following various dosing regimens were simulated. RESULTS: Serum IgG levels, with significant inter-patient variability, correlated with dose and treatment interruptions at the individual patient level. Simulated data for various dosing regimens (0.4-2 g/kg once every 1-4 weeks [Q1-4W]) revealed that more frequent dosing provided more stable IgG levels than less frequent dosing, and dose splitting over multiple days had no significant effects on PK. DISCUSSION: In patients with MMN, stable dosing and consistent serum IgG levels are crucial to avoid negative responses owing to treatment interruptions. Dosing intervals more frequent than Q4W may alleviate periodic symptom deterioration. Dose splitting potentially offers flexibility for patients requiring large volumes of IVIG without negatively affecting serum IgG PK, while maintaining treatment efficacy. Variability in serum IgG levels between patients suggests that individualizing IVIG treatment regimens and target IgG levels may play a key role in managing MMN.

Despite persistent public health initiatives, many women continue to smoke during pregnancy. Since maternal smoking has been linked to persisting sex-dependent neurobehavioral deficits in offspring, some consider nicotine to be a safer alternative to tobacco during pregnancy, and the use of electronic nicotine delivery systems is on the rise. We presently show, however, that sustained exposure to low doses of nicotine during fetal development, approximating plasma levels seen clinically with the nicotine patch, produces substantial changes in developing corticostriatal dopamine systems in adolescence. Briefly, pregnant dams were implanted on gestational day 4 with an osmotic minipump that delivered either saline (GS) or nicotine (3 mg/kg/day) (GN) for two weeks. At birth, pups were cross-fostered with treatment naïve dams and were handled daily. Biochemical analyses, signaling assays, and behavioral responses to cocaine were assessed on postnatal day 32, representative of adolescence in the rodent. GN treatment had both sex-dependent and sex-independent effects on prefrontal dopamine systems, altering Catechol-O-methyl transferase (COMT)-dependent dopamine turnover in males and norepinephrine transporter (NET) binding expression in both sexes. GN enhanced cocaine-induced locomotor activity in females, concomitant with GN-induced reductions in striatal dopamine transporter (DAT) binding. GN enhanced ventral striatal D2-like receptor expression and G-protein coupling, while altering the roles of D2 and D3 receptors in cocaine-induced behaviors. These data show that low-dose prenatal nicotine treatment sex-dependently alters corticostriatal dopamine system development, which may underlie clinical deficits seen in adolescents exposed to tobacco or nicotine in utero.