A growing number of population pharmacokinetic analyses of therapeutic monoclonal antibodies (mAbs) have been published in the scientific literature. The aims of this article are to summarize the findings from these studies and to relate the findings to the general pharmacokinetic and structural characteristics of therapeutic mAbs. A two-compartment model was used in the majority of the population analyses to describe the disposition of the mAb. Population estimates of the volumes of distribution in the central (V(1)) and peripheral (V(2)) compartments were typically small, with median (range) values of 3.1 (2.4-5.5) L and 2.8 (1.3-6.8) L, respectively. The estimated between-subject variability in the V(1) was usually moderate, with a median (range) coefficient of variation (CV) of 26% (12-84%). Between-subject variability in other distribution-related parameters such as the V(2) and intercompartmental clearance were often not estimated. Although the pharmacokinetic models used most frequently in the population analyses were models with linear clearance, other models with nonlinear, or parallel linear and nonlinear clearance pathways were also applied, as many therapeutic mAbs are eliminated via saturable target-mediated mechanisms. Population estimates of the maximum elimination rate (V(max)) and the mAb concentration at which elimination was at half maximum for Michaelis-Menten-type elimination pathways varied considerably among the different therapeutic mAbs. However, estimates of the total clearance (CL) of mAbs with linear clearance characteristics and of the clearance of mAbs via the linear clearance pathway (CL(L)) with parallel linear and nonlinear clearance were quite similar for the different mAbs and typically ranged from 0.2 to 0.5 L/day, which is relatively close to the estimated clearance of endogenous IgG of 0.21 L/day. The between-subject variability in the V(max), CL and CL(L) was moderate to high, with estimated CVs ranging from 15% to 65%. Measures of body size were the covariates most commonly identified as influencing the pharmacokinetics of therapeutic mAbs. In summary, many features of the population pharmacokinetics of currently used therapeutic mAbs are similar, despite differences in their pharmacological targets and studied patient populations.

SummaryBackgroundVedolizumab, an anti‐α4β7 integrin monoclonal antibody (mAb), is indicated for treating patients with moderately to severely active ulcerative colitis (UC) and Crohn's disease (CD). As higher therapeutic mAb concentrations have been associated with greater efficacy in inflammatory bowel disease, understanding determinants of vedolizumab clearance may help to optimise dosing.AimsTo characterise vedolizumab pharmacokinetics in patients with UC and CD, to identify clinically relevant determinants of vedolizumab clearance, and to describe the pharmacokinetic–pharmacodynamic relationship using population modelling.MethodsData from a phase 1 healthy volunteer study, a phase 2 UC study, and 3 phase 3 UC/CD studies were included. Population pharmacokinetic analysis for repeated measures was conducted using nonlinear mixed effects modelling. Results from the base model, developed using extensive phase 1 and 2 data, were used to develop the full covariate model, which was fit to sparse phase 3 data.ResultsVedolizumab pharmacokinetics was described by a 2‐compartment model with parallel linear and nonlinear elimination. Using reference covariate values, linear elimination half‐life of vedolizumab was 25.5 days; linear clearance (CLL) was 0.159 L/day for UC and 0.155 L/day for CD; central compartment volume of distribution (V c) was 3.19 L; and peripheral compartment volume of distribution was 1.66 L. Interindividual variabilities (%CV) were 35% for CLL and 19% for V c; residual variance was 24%. Only extreme albumin and body weight values were identified as potential clinically important predictors of CLL.ConclusionsPopulation pharmacokinetic parameters were similar in patients with moderately to severely active UC and CD. This analysis supports use of vedolizumab fixed dosing in these patients. Clinicaltrials.gov Identifiers: NCT01177228; NCT00783718 (GEMINI 1); NCT00783692 (GEMINI 2); NCT01224171 (GEMINI 3).

Higher vedolizumab serum concentrations were associated with higher remission rates after induction therapy in patients with moderately to severely active UC or CD. This relationship is affected by several factors, including previous TNFα antagonist use. Prospective studies are needed to assess vedolizumab dose individualisation and optimisation.

Vedolizumab is a humanized anti-α4β7 integrin monoclonal antibody that selectively blocks trafficking of memory T cells to inflamed gut tissue by inhibiting the α4β7-mucosal addressin cell adhesion molecule-1 (MAdCAM-1) interaction. Approved for treating patients with moderately to severely active ulcerative colitis (UC) or Crohn’s disease (CD), vedolizumab is administered as a 300 mg intravenous infusion. Vedolizumab undergoes a rapid, saturable, non-linear, target-mediated elimination process at low concentrations and a slower, linear, non-specific elimination process at higher concentrations. At therapeutic concentrations, vedolizumab primarily undergoes linear elimination. From population pharmacokinetic modeling, the vedolizumab terminal elimination half-life (t ½ β) was estimated to be 25.5 days; linear clearance (CLL) was similar for patients with UC (0.159 L/day) and CD (0.155 L/day). Extreme low albumin concentrations and extreme high body weight values were potentially clinically important predictors of vedolizumab CLL. Other factors, including concomitant therapy use (methotrexate, azathioprine, mercaptopurine, or aminosalicylates) or prior tumor necrosis factor-α (TNF-α) antagonist use, had no clinically relevant effects on CLL. A positive exposure–efficacy relationship for clinical remission and clinical response was apparent for vedolizumab induction therapy in patients with UC or CD. On average, patients with higher albumin, lower fecal calprotectin (UC only), lower C-reactive protein (CD only), and no prior TNF-α antagonist use had a higher probability of remission. Off drug, 10% of patients with UC or CD were positive for anti-drug antibodies. This article provides a comprehensive review of the clinical pharmacokinetics, pharmacodynamics, exposure–efficacy relationships, and immunogenicity of vedolizumab.

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Cetuximab is a monoclonal antibody directed against the epidermal growth factor receptor and is indicated in the treatment of squamous cell carcinoma of the head and neck. The population pharmacokinetics of cetuximab were characterized by nonlinear mixed effects modeling (NONMEM V) using a total of 912 concentrations from 143 patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck enrolled in 2 phase I/II studies. Cetuximab pharmacokinetics were best described by a 2-compartment model with Michaelis-Menten-type saturable elimination. Population estimates (between-subject variability, percent coefficient of variation) of the pharmacokinetic parameters were V(max) 4.38 mg/h (15.4%), K(m) 74 mug/mL, central compartment volume V(1) 2.83 L (18.6%), peripheral compartment volume 2.43 L (56.4%), and intercompartmental clearance 0.103 L/h (97.2%). Ideal body weight and white blood cell count were identified as predictors of V(max) and total body weight as a predictor of V(1). Clinical dose adjustments beyond the approved body surface area-based dosing of cetuximab may be warranted in patients with extreme deviations of their actual body weight from ideal body weight. Agreement between simulated and measured concentrations monitored for up to 43 weeks of therapy indicates that cetuximab pharmacokinetic parameters remained constant during prolonged therapy.

Summary Background Prospectively designed studies assessing the exposure‐response profile of vedolizumab are lacking. Observational exposure‐response data for vedolizumab are limited and have not been adjusted for potential confounding factors, particularly those that may affect vedolizumab clearance. Aims To (a) investigate the vedolizumab exposure‐response relationship after adjusting for potential confounding variables; (b) propose potential target serum vedolizumab concentrations for future study; (c) ascertain whether early vedolizumab serum concentrations were associated with short‐ and long‐term clinical outcomes in adults with ulcerative colitis in GEMINI 1. Methods Propensity‐score‐based case‐matching analysis was performed using data from GEMINI 1 and an earlier large population pharmacokinetic study, with vedolizumab clearance or concentration as predictors of clinical remission and response, adjusted for age, weight, anti‐tumour necrosis factor alpha therapy history, serum albumin and faecal calprotectin concentrations. Potential vedolizumab concentration targets at weeks 6, 14 and steady state were proposed. Association between early vedolizumab concentrations at weeks 2, 4 and 6 and clinical remission at weeks 14 and 52 was evaluated. Results Among 693 patients with pharmacokinetic data at week 6, potential target vedolizumab concentrations at weeks 6, 14 and steady state were 37.1, 18.4 and 12.7 µg/mL respectively. Week 6 was identified as the earliest time at which vedolizumab concentrations were consistently associated with clinical remission at weeks 14 and 52. Conclusions In this comprehensively adjusted analysis, vedolizumab concentrations at week 6 were associated with short‐ and long‐term remission. Potential induction and maintenance target concentrations were proposed for further study.

mediates lymphocyte trafficking to gastrointestinal mucosa and gut-associated lymphoid tissue through mucosal addressin cell adhesion molecule-1 (MAdCAM 1). 1 The novel mechanism of action of vedolizumab allows it to bind exclusively to the α 4 β 7 integrin, antagonizing its adherence to MAdCAM-1 and thereby impairing the migration of leukocytes into gastrointestinal mucosa. 1 The gut-selective, anti-inflammatory activity of vedolizumab enables targeted therapy without generalized immunosuppression. Vedolizumab intravenous (IV), a lyophilized formulation of vedolizumab intended for IV infu