Recombinant Alpha-1 Antitrypsin-Fc Fusion Protein INBRX-101 in Adults With Alpha-1 Antitrypsin Deficiency: A Phase 1 Study.

Background: Alpha-1 antitrypsin deficiency (AATD) is characterized by low alpha-1 antitrypsin (AAT) levels, predisposing individuals to lung disease. The standard of care, plasma-derived AAT (pdAAT), is delivered as weekly infusions to maintain serum AAT concentrations ≥11µM (≈50% of those in healthy individuals). INBRX-101, a recombinant human AAT-Fc fusion protein, was designed to have a longer half-life and achieve higher AAT levels than pdAAT. Methods: In this phase 1 dose-escalation study (N=31), adults with AATD received 1 dose (part 1) or 3 doses (part 2) of 10 (part 1), 40, 80, or 120mg/kg INBRX-101 every 3 weeks (Q3W) via intravenous infusion. The primary endpoint was safety and tolerability. Secondary endpoints were pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of INBRX-101. Results: INBRX-101 was well tolerated. Most treatment-emergent adverse events were grade ≤2. In part 2 (n=18; each dose, n=6), dose-related increases in serum functional AAT (fAAT) were observed; mean fAAT levels remained above the 21 µM target for up to 4 weeks after the final dose in the 120-mg/kg cohort. Antidrug antibodies had no meaningful impact on PK or PD. INBRX-101 was detected in pulmonary epithelial lining fluid (PELF) from all patients assessed (n=11), and PELF fAAT increased after dosing. PK/PD modeling projected steady-state serum fAAT ≥21µM at 120 mg/kg Q3W (average concentration ≈43µM; trough concentration ≈28µM) and Q4W (≈34µM; ≈21µM). Conclusion: The favorable safety profile and ability to maintain serum fAAT levels >21µM with extended-interval dosing, support a phase 2 trial evaluating Q3W and Q4W dosing of INBRX-101.

Mechanistic Pharmacokinetic/Pharmacodynamic Modeling in Support of a Patient-Convenient, Longer Dosing Interval for Carfilzomib, a Covalent Inhibitor of the Proteasome.

BACKGROUND: Carfilzomib is an irreversible second-generation proteasome inhibitor that has a short elimination half-life but much longer pharmacodynamic (PD) effect based on its irreversible mechanism of action, making it amenable to longer dosing intervals. A mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model was built using a bottom-up approach, based on the mechanism of action of carfilzomib and the biology of the proteasome, to provide further evidence of the comparability of once-weekly and twice-weekly dosing. METHODS: The model was qualified using clinical data from the phase III ENDEAVOR study, where the safety and efficacy of bortezomib (a reversible proteasome inhibitor) and carfilzomib were compared. Simulations were performed to compare the average proteasome inhibition across five cycles of treatment for the 20/70 mg/m2 once-weekly (70 QW) and 20/56 mg/m2 twice-weekly (56 BIW) regimens. RESULTS: Results indicated that while 70 QW had a higher maximum concentration (Cmax) and lower steady-state area under the concentration-time curve (AUC) than 56 BIW, the average proteasome inhibition after five cycles of treatment between the regimens was comparable. Presumably, the higher Cmax of carfilzomib from 70 QW compensates for the lower overall AUC compared with 56 BIW, and hence 70 QW is expected to have comparable proteasome inhibition, and therefore comparable efficacy, to 56 BIW. The comparable model-predicted proteasome inhibition between 70 QW and 56 BIW also translated to comparable clinical response, in terms of overall response rate and progression-free survival. CONCLUSION: This work provides a framework for which mechanistic PK/PD modeling can be used to guide optimization of dosing intervals for therapeutics with significantly longer PD effects than PK, and help further justify patient-convenient, longer dosing intervals.

Systematic Evaluation of the Effect of Formulation Variables on In Vitro Performance of Mometasone Furoate Suspension-Metered Dose Inhalers.

The therapeutic benefits of metered dose inhalers (MDIs) in pulmonary disorders are mainly driven by aerosol performance, which depends on formulation variables (drug and excipients), device design, and patient interactions. The present study provides a comprehensive investigation to better understand the effect of formulation variables on mometasone furoate (MF) suspension-based MDI product performance. The effects of MF particle size (volume median diameter; X50) and excipient concentration (ethanol and oleic acid, cosolvent, and surfactant, respectively) on selected critical quality attributes (delivered dose (DD), fine particle dose of particles lesser than 5 µm (FPD < 5), ex-throat dose and median dissolution time (MDT)) were studied. Eight MF-MDI formulations (one per batch) were manufactured based on a reduced factorial design of experiment (DOE) approach, which included relevant formulation levels with varying X50 (1.1 and 2 µm), concentration of ethanol (0.45, 0.9, 1.8, and 3.6%w/w), and oleic acid (0.001 and 0.025%w/w). The in vitro evaluation of these MF-MDI formulations indicated the importance of drug particle's X50, oleic acid, and ethanol canister concentration as critical formulation variables governing the performance of MF suspension-based MDI products. The effect of these formulation variables on DD, FPD < 5, ex-throat dose, and MDT was subsequently utilized to develop empirical relationships linking formulation factors with effects on in vitro performance measures. The developed strategy could be useful for predicting MF-MDI product performance during MDI product development and manufacturing. The systematic DOE approach utilized in this study may provide insights into the understanding of the formulation variables governing the MF-MDI product performance.

Optimization of the Transwell® System for Assessing the Dissolution Behavior of Orally Inhaled Drug Products through In Vitro and In Silico Approaches.

The aim of this study was to further evaluate and optimize the Transwell® system for assessing the dissolution behavior of orally inhaled drug products (OIDPs), using fluticasone propionate as a model drug. Sample preparation involved the collection of a relevant inhalable dose fraction through an anatomical mouth/throat model, resulting in a more uniform presentation of drug particles during the subsequent dissolution test. The method differed from previously published procedures by (1) using a 0.4 µm polycarbonate (PC) membrane, (2) stirring the receptor compartment, and (3) placing the drug-containing side of the filter paper face downwards, towards the PC membrane. A model developed in silico, paired with the results of in vitro studies, suggested that a dissolution medium providing a solubility of about 5 µg/mL would be a good starting point for the method's development, resulting in mean transfer times that were about 10 times longer than those of a solution. Furthermore, the model suggested that larger donor/receptor and sampling volumes (3, 3.3 and 2 mL, respectively) will significantly reduce the so-called "mass effect". The outcomes of this study shed further light on the impact of experimental conditions on the complex interplay of dissolution and diffusion within a volume-limited system, under non-sink conditions.

Predicting Pulmonary Pharmacokinetics from In Vitro Properties of Dry Powder Inhalers.

PURPOSE: The ability of two semi-mechanistic simulation approaches to predict the systemic pharmacokinetics (PK) of inhaled corticosteroids (ICSs) delivered via dry powder inhalers (DPIs) was assessed for mometasone furoate, budesonide and fluticasone propionate. METHODS: Both approaches derived the total lung doses and the central to peripheral lung deposition ratios from clinically relevant cascade impactor studies, but differed in the way the pulmonary absorption rate was derived. In approach 1, the rate of in vivo drug dissolution/absorption was predicted for the included ICSs from in vitro aerodynamic particle size distribution and in vitro drug solubility estimates measured in an in vivo predictive dissolution medium. Approach 2 derived a first order absorption rate from the mean dissolution time (MDT), determined for the test formulations in an in vitro Transwell® based dissolution system. RESULTS: Approach 1 suggested PK profiles which agreed well with the published pharmacokinetic profiles. Similarly, within approach 2, input parameters for the pulmonary absorption rate constant derived from dissolution rate experiments were able to reasonably predict the pharmacokinetic profiles published in literature. CONCLUSION: Approach 1 utilizes more complex strategies for predicting the dissolution/absorption process without providing a significant advantage over approach 2 with regard to accuracy of in vivo predictions.

Evaluation of the Transwell System for Characterization of Dissolution Behavior of Inhalation Drugs: Effects of Membrane and Surfactant.

Assessing the dissolution behavior of orally inhaled drug products (OIDs) has been proposed as an additional in vitro test for the characterization of innovator and generic drug development. A number of suggested dissolution methods (e.g., commercially available Transwell or Franz cell systems) have in common a membrane which provides the separation between the donor compartment, containing nondissolved drug particles, and an acceptor (sampling) compartment into which dissolved drug will diffuse. The goal of this study was to identify and overcome potential pitfalls associated with such dissolution systems using the inhaled corticosteroids (ICS), viz., budesonide, ciclesonide, and fluticasone propionate, as model compounds. A respirable fraction (generally stage 4 of a humidity, flow, and temperature controlled Andersen Cascade Impactor (ACI) or a Next Generation Impactor (NGI)) was collected for the tested MDIs. The dissolution behavior of these fractions was assessed employing the original and an adapted Transwell system using dissolution media which did or did not contain surfactant (0.5% sodium dodecyl sulfate). The rate with which the ICS transferred from the donor to the acceptor compartment was assessed by HPLC. Only a modified system that incorporated faster equilibrating membranes instead of the original 0.4 µm Transwell membrane resulted in dissolution and not diffusion being the rate-limiting step for the transfer of drug from the donor to the acceptor compartment. Experiments evaluating the nature of the dissolution media suggested that the presence of a surfactant (e.g., 0.5% SDS) is essential to obtain rank order of dissolution rates (e.g., for budesonide, fluticasone propionate, and ciclesonide) that is in agreement with absorption rates of these ICS obtained in studies of human pharmacokinetics. Using the optimized procedure, the in vitro dissolution behavior of budesonide, ciclesonide, and fluticasone propionate agreed approximately with descriptors of in vivo absorption. The optimized procedure, using membranes with increased permeability and surfactant containing dissolution medium, represents a good starting point to further evaluate in vitro/in vivo correlations.