Considerations for Industry-Preparing for the FDA Model-Informed Drug Development (MIDD) Paired Meeting Program.

A recent industry perspective published in this journal describes the benefits received by drug companies from participation in the MIDD Pilot Program. Along with the primary objectives of supporting good decision-making in drug development, there were substantial savings in time and development costs. Furthermore, many sponsors reported qualitative benefits such as new learnings and clarity on MIDD strategies and methodology that could be applied to other development programs. Based on the success of the Pilot Program, the FDA recently announced the continuation of the MIDD Paired Meeting Program as part of the Prescription Drug User Fee Act (PDUFA VII). In this report, we describe the collective experiences of industry participants in the MIDD Program to date, including all aspects of the process from meeting request submission to follow-up actions. The purpose is to provide future participants with information to optimize the value of the MIDD Program.

Pharmacokinetic and pharmacodynamic properties of once-weekly insulin icodec in individuals with type 1 diabetes.

AIMS: To investigate the pharmacokinetic/pharmacodynamic properties of once-weekly insulin icodec in individuals with type 1 diabetes (T1D). MATERIALS AND METHODS: In this randomized, open-label, two-period crossover trial, 66 individuals with T1D (age 18-64 years; glycated haemoglobin ≤75 mmol/mol [≤ 9%]) were to receive once-weekly icodec (8 weeks) and once-daily insulin glargine U100 (2 weeks) at individualized fixed equimolar total weekly doses established during up to 10 weeks' run-in with glargine U100 titrated to pre-breakfast plasma glucose (PG) of 4.4-7.2 mmol/L (80-130 mg/dL). Insulin aspart was used as bolus insulin. Blood sampling for icodec pharmacokinetics was performed from the first icodec dose until 35 days after the last dose. The glucose infusion rate at steady state was assessed in glucose clamps (target 6.7 mmol/L [120 mg/dL]) at 16-52 h and 138-168 h after the last icodec dose and 0-24 h after the last glargine U100 dose. Icodec pharmacodynamics during 1 week were predicted by pharmacokinetic-pharmacodynamic modelling. Hypoglycaemia was recorded during the treatment periods based on self-measured PG. RESULTS: Icodec reached pharmacokinetic steady state on average within 2-3 weeks. At steady state, model-predicted daily proportions of glucose infusion rate during the 1-week dosing interval were 14.3%, 19.6%, 18.3%, 15.7%, 13.1%, 10.6% and 8.4%, respectively. Rates and duration of Level 2 hypoglycaemic episodes (PG <3.0 mmol/L [54 mg/dL]) were 32.8 versus 23.9 episodes per participant-year of exposure and 33 ± 25 versus 30 ± 18 min (mean ± SD) for icodec versus glargine U100. CONCLUSIONS: The pharmacokinetic/pharmacodynamic properties of icodec suggest its potential to provide basal coverage in a basal-bolus insulin regimen in people with T1D.

Pharmacokinetic and Pharmacodynamic Characteristics of Insulin Icodec After Subcutaneous Administration in the Thigh, Abdomen or Upper Arm in Individuals with Type 2 Diabetes Mellitus.

BACKGROUND AND OBJECTIVE: Individuals with diabetes mellitus may prefer different body regions for subcutaneous insulin administration. This trial investigated whether choice of injection region affects exposure and glucose-lowering effect of once-weekly basal insulin icodec. METHODS: In a randomised, open-label, crossover trial, 25 individuals with type 2 diabetes received single subcutaneous icodec injections (5.6 U/kg) in the thigh, abdomen or upper arm (9-13 weeks' washout). Pharmacokinetic blood sampling occurred frequently until 35 days post-dose. Partial glucose-lowering effect was assessed 36-60 h post-dose in a glucose clamp (target 7.5 mmol/L). Steady-state pharmacokinetics following multiple once-weekly dosing were simulated using a two-compartment pharmacokinetic model. RESULTS: Total icodec exposure (area under the curve from zero to infinity after single dose; AUC0-∞,SD) was similar between injection in the thigh, abdomen and upper arm (estimated AUC0-∞,SD ratios [95% confidence interval]: abdomen/thigh 1.02 [0.96-1.09], p = 0.473; upper arm/thigh 1.04 [0.98-1.10], p = 0.162; abdomen/upper arm 0.98 [0.93-1.05], p = 0.610). Maximum icodec concentration (Cmax) after single dose was higher for abdomen (by 17%, p = 0.002) and upper arm (by 24%, p < 0.001) versus thigh. When simulated to steady state, smaller differences in Cmax were seen for abdomen (by 11%, p = 0.004) and upper arm (by 16%, p < 0.001) versus thigh. Geometric mean [coefficient of variation] glucose-lowering effect 36-60 h post-dose was comparable between the thigh (1961 mg/kg [51%]), abdomen (2130 mg/kg [52%]) and upper arm (2391 mg/kg [40%]). CONCLUSION: Icodec can be administered subcutaneously in the thigh, abdomen or upper arm with no clinically relevant difference in exposure and with a similar glucose-lowering effect. GOV IDENTIFIER: NCT04582448.

Dose/exposure-response modeling in dose titration trials: Overcoming the titration paradox.

Response-based dose individualization or dose titration is a powerful approach to achieve precision dosing. Yet, titration as an individualization strategy is underused in drug development and therefore not reflected in labeling, possibly partly because of the data analysis challenges associated with assessing dose/exposure-response under dose titration, where there is an inherent risk of selection bias because poor responders would get high doses, whereas good responders would get low doses. In a recent article, this issue of selection bias was termed the "titration paradox." In this study, we demonstrate by means of simulation that the titration paradox may be overcome if longitudinal data from dose titration trials is analyzed using a population approach that accounts for the fact that dose/exposure-response relationships differ between individuals. We show that with an appropriate sample size and missing data missing at random, stepwise dose/exposure-response modeling based on data obtained under dose titration is not by definition subject to model selection bias or bias in parameter estimates. We also illustrate the challenges of graphical exploration of data obtained under dose titration and discuss the use of model diagnostic tools with such data. Our study shows that if, at every timepoint in the course of a trial, there is a clear causal relationship between the response and the dose/exposure level, and a population approach is used, it will in many cases be possible to develop, estimate, and appropriately qualify a dose/exposure-response model also for data obtained under dose titration, thus overcoming the titration paradox.

Molecular and pharmacological characterization of insulin icodec: a new basal insulin analog designed for once-weekly dosing.

INTRODUCTION: Insulin icodec is a novel, long-acting insulin analog designed to cover basal insulin requirements with once-weekly subcutaneous administration. Here we describe the molecular engineering and the biological and pharmacological properties of insulin icodec. RESEARCH DESIGN AND METHODS: A number of in vitro assays measuring receptor binding, intracellular signaling as well as cellular metabolic and mitogenic responses were used to characterize the biological properties of insulin icodec. To evaluate the pharmacological properties of insulin icodec in individuals with type 2 diabetes, a randomized, double-blind, double-dummy, active-controlled, multiple-dose, dose escalation trial was conducted. RESULTS: The long half-life of insulin icodec was achieved by introducing modifications to the insulin molecule aiming to obtain a safe, albumin-bound circulating depot of insulin icodec, providing protracted insulin action and clearance. Addition of a C20 fatty diacid-containing side chain imparts strong, reversible albumin binding, while three amino acid substitutions (A14E, B16H and B25H) provide molecular stability and contribute to attenuating insulin receptor (IR) binding and clearance, further prolonging the half-life. In vitro cell-based studies showed that insulin icodec activates the same dose-dependent IR-mediated signaling and metabolic responses as native human insulin (HI). The affinity of insulin icodec for the insulin-like growth factor-1 receptor was proportionately lower than its binding to the IR, and the in vitro mitogenic effect of insulin icodec in various human cells was low relative to HI. The clinical pharmacology trial in people with type 2 diabetes showed that insulin icodec was well tolerated and has pharmacokinetic/pharmacodynamic properties that are suited for once-weekly dosing, with a mean half-life of 196 hours and close to even distribution of glucose-lowering effect over the entire dosing interval of 1 week. CONCLUSIONS: The molecular modifications introduced into insulin icodec provide a novel basal insulin with biological and pharmacokinetic/pharmacodynamic properties suitable for once-weekly dosing. TRIAL REGISTRATION NUMBER: NCT02964104.

Insulin degludec's ultra-long pharmacokinetic properties observed in adults are retained in children and adolescents with type 1 diabetes.

Insulin degludec (IDeg) is a basal insulin with an ultra-long pharmacokinetic profile in adults that at steady-state produces remarkably flat and stable insulin levels; however, no studies have yet reported on the pharmacokinetic properties of IDeg in subjects younger than 18 years of age. This was a single-centre, randomised, single-dose, double-blind, two-period crossover trial conducted in children (6-11 years), adolescents (12-17 years), and adults (18-65 years) with type 1 diabetes. Subjects received a single subcutaneous dose of 0.4 U/kg IDeg or insulin glargine (IGlar), respectively, on two separate dosing visits, with pharmacokinetic blood sampling up to 72-h postdose. A total of 37 subjects (12 children, 13 adolescents, and 12 adults) completed the trial. Total exposure of IDeg after a single dose (AUCIDeg ,0-∞, SD ) was higher in children compared to adults [estimated ratio children/adults 1.48 (95% confidence interval, CI: 0.98; 2.24)] and in adolescents compared to adults [estimated ratio adolescents/adults 1.33 (95% CI: 1.08; 1.64)]; however, the difference was only statistically significant for the latter comparison. No statistically significant difference in maximum concentration of IDeg (Cmax, IDeg , SD ) was observed. Estimated ratios for Cmax, IDeg , SD were (children/adults) 1.20 (95% CI: 0.90; 1.60) and (adolescents/adults) 1.23 (95% CI: 1.00; 1.51). Simulated mean steady state pharmacokinetic profiles supported a flat and stable IDeg exposure across a 24-h dosing interval. IDeg was detectable in serum for at least 72 h (end of blood sampling period) in all subjects following single dose. In conclusion, the ultra-long pharmacokinetic properties of IDeg observed in adults are preserved in children and adolescents with type 1 diabetes.

Clearance of rFVIIa and NN1731 after intravenous administration to Beagle dogs.

AIM: NN1731 is a recombinant activated factor VII (rFVIIa) analogue with enhanced activity. The objective of the present study was to evaluate the clearance mechanisms of rFVIIa and NN1731 after intravenous administration to Beagle dogs. METHODS: The study was performed in Beagle dogs administered with a single dose of 5.4 nmol/kg rFVIIa or NN1731 intravenously. Plasma samples collected up to 12-h post-administration were analysed using three different assays to determine FVIIa clot activity (FVIIa:C), total FVIIa antigen, and levels of FVIIa-antithrombin (AT) complexes. Pharmacokinetic parameters were determined by use of standard non-compartmental and non-linear mixed effects methods. RESULTS: For both compounds, complex formation with AT accounted for the observed difference between the activity and the antigen curves and constituted 60-70% of the total clearance. The clearance of rFVIIa and NN1731 was estimated to be 73 and 214 mL/h/kg, respectively, accordingly, AT complex formation occurred around three times faster for NN1731. The difference in activity observed in the initial phase, resulting in distribution half-lives of 0.71 and 0.22 h for rFVIIa and NN1731, was mainly caused by the 3-fold difference in clearance. The terminal half-life of rFVIIa and NN1731 was estimated to be 2.1 and 2.5 h, respectively. The non-compartmental analysis resulted in almost identical parameters. CONCLUSION: The present study demonstrates that the difference between the activity and the antigen profiles of rFVIIa and NN1731 in Beagle dogs is the result of complex formation with AT which constitutes a major pathway for the clearance of rFVIIa activity.

Population stochastic modelling (PSM)--an R package for mixed-effects models based on stochastic differential equations.

The extension from ordinary to stochastic differential equations (SDEs) in pharmacokinetic and pharmacodynamic (PK/PD) modelling is an emerging field and has been motivated in a number of articles [N.R. Kristensen, H. Madsen, S.H. Ingwersen, Using stochastic differential equations for PK/PD model development, J. Pharmacokinet. Pharmacodyn. 32 (February(1)) (2005) 109-141; C.W. Tornøe, R.V. Overgaard, H. Agersø, H.A. Nielsen, H. Madsen, E.N. Jonsson, Stochastic differential equations in NONMEM: implementation, application, and comparison with ordinary differential equations, Pharm. Res. 22 (August(8)) (2005) 1247-1258; R.V. Overgaard, N. Jonsson, C.W. Tornøe, H. Madsen, Non-linear mixed-effects models with stochastic differential equations: implementation of an estimation algorithm, J. Pharmacokinet. Pharmacodyn. 32 (February(1)) (2005) 85-107; U. Picchini, S. Ditlevsen, A. De Gaetano, Maximum likelihood estimation of a time-inhomogeneous stochastic differential model of glucose dynamics, Math. Med. Biol. 25 (June(2)) (2008) 141-155]. PK/PD models are traditionally based ordinary differential equations (ODEs) with an observation link that incorporates noise. This state-space formulation only allows for observation noise and not for system noise. Extending to SDEs allows for a Wiener noise component in the system equations. This additional noise component enables handling of autocorrelated residuals originating from natural variation or systematic model error. Autocorrelated residuals are often partly ignored in PK/PD modelling although violating the hypothesis for many standard statistical tests. This article presents a package for the statistical program R that is able to handle SDEs in a mixed-effects setting. The estimation method implemented is the FOCE(1) approximation to the population likelihood which is generated from the individual likelihoods that are approximated using the Extended Kalman Filter's one-step predictions.

Using stochastic differential equations for PK/PD model development.

A method for PK/PD model development based on stochastic differential equation models is proposed. The new method has a number of advantages compared to conventional methods. In particular, the new method avoids the exhaustive trial-and-error based search often conducted to determine the most appropriate model structure, because it allows information about the appropriate model structure to be extracted directly from data. This is accomplished through quantification of the uncertainty of the individual parts of an initial model, by means of which tools for performing model diagnostics can be constructed and guidelines for model improvement provided. Furthermore, the new method allows time-variations in key parameters to be tracked and visualized graphically, which allows important functional relationships to be revealed. Using simulated data, the performance of the new method is demonstrated by means of two examples. The first example shows how, starting from a simple assumption of linear PK, the method can be used to determine the correct nonlinear model for describing the PK of a drug following an oral dose. The second example shows how, starting from a simple assumption of no drug effect, the method can be used to determine the correct model for the nonlinear effect of a drug with known PK in an indirect response model.