Evaluation of covariate effects using forest plots and introduction to the coveffectsplot R package

The current tutorial describes why forest plots are needed for an effective communication of covariates effects, how they are constructed, and how they should be presented. Simulation-based methodologies allowing the user to evaluate the marginal impact of changing one covariate at a time or by considering the joint effects of correlated covariates are introduced along with graphical tools for an optimal assessment of the covariate effects. The R package coveffectsplot and an associated R Shiny application are provided to facilitate the design and construction of forest plots for the visualization of covariate effects. All codes and materials are available on a public Github repository.

Population Pharmacokinetics and Pharmacodynamics of Ontamalimab (SHP647), a Fully Human Monoclonal Antibody Against Mucosal Addressin Cell Adhesion Molecule-1 (MAdCAM-1), in Patients With Ulcerative Colitis or Crohn's Disease

Ontamalimab (SHP647) is a fully human, immunoglobulin G₂, antihuman mucosal addressin cell adhesion molecule‐1 (MAdCAM‐1) monoclonal antibody being developed for the treatment of ulcerative colitis (UC) and Crohn's disease (CD). A population pharmacokinetic/pharmacodynamic (PK/PD) analysis was conducted using clinical phase 2 study data to evaluate the PK and PD of ontamalimab following subcutaneous administrations of 7.5, 22.5, 75, and 225 mg every 4 weeks in patients with moderate to severe UC or CD. A total of 440 patients with UC (n = 249; 56.6%) or CD (n = 191; 43.4%) were included in the analysis. A 2‐compartment model with parallel linear and nonlinear elimination adequately characterized concentration‐time profiles of ontamalimab. The apparent clearance and volume of distribution were 0.0127 L/h (0.305 L/day) and 6.53 L, respectively. Apparent clearance and volume of distribution were mainly dependent on baseline albumin and body weight, respectively. No differences in the PK properties of ontamalimab were observed between patients with UC or CD. The presence of antidrug antibodies did not impact the PK of ontamalimab. Nonlinear elimination occurred at very low concentrations and was unlikely to contribute to the elimination half‐life under steady‐state conditions. A linear PK/PD model described the relationship between ontamalimab and free MAdCAM‐1. Minimum concentrations of ontamalimab at steady state following 75 mg every 4 weeks were associated with >95% suppression of circulating free MAdCAM‐1. The PK/PD properties characterized support phase 3 testing in UC and CD.

An evaluation of the pharmacokinetics of treprostinil diolamine in subjects with hepatic impairment

WHAT IS KNOWN AND OBJECTIVE

Treprostinil diolamine (oral treprostinil) is a prostacyclin analogue under evaluation for the treatment for pulmonary arterial hypertension (PAH). This study assessed the pharmacokinetics (PK) and safety of treprostinil following oral administration of a single sustained-release 1 mg dose in subjects with hepatic impairment.

METHODS

Four cohorts, including healthy volunteers, and subjects with mild, moderate and severe hepatic impairment were enrolled. Thirty subjects completed the study. Mean treprostinil clearance values (CL/F) decreased with the severity of hepatic impairment. The decrease in CL/F resulted in a marked increase in exposure levels of treprostinil. Relative to healthy subjects, mean area under the curve from time zero to 24 h after dosing interval (AUC0-24) values in subjects with mild, moderate and severe hepatic impairment increased by approximately 2·2-, 4·9- and 7·6-fold, respectively. The most frequent adverse events (AEs) exhibited in this study were similar to those seen with prostacyclin and its analogues and with AEs seen in other clinical studies with oral treprostinil (e.g. headache, diarrhoea and nausea). The overall incidence of all AEs and the specific events of headache and nausea increased with severity of hepatic impairment.

WHAT IS NEW AND CONCLUSION

Based on these results, dosage adjustments should be performed in subjects with hepatic impairment.