Impact of immunogenicity on pharmacokinetics, efficacy and safety of adalimumab in adult patients with moderate to severe chronic plaque psoriasis

BackgroundAdalimumab is a tumour necrosis factor-alpha antibody approved for treatment of moderate to severe chronic plaque psoriasis. ObjectiveTo characterise population pharmacokinetics of adalimumab 40 mg every other week dosing regimen and impact of immunogenicity on pharmacokinetics, efficacy and safety in psoriasis patients. MethodsPatients were enrolled in a Phase 3 study comprising a 16-week double-blind, placebo-controlled period, a 17-week open-label period for Week 16 Psoriasis Area and Severity Index (PASI) 75 responders, and a 19-week double-blind, placebo-controlled period for Week 33 PASI 75 responders. Serum adalimumab and anti-adalimumab antibody (AAA) concentrations were measured and a population pharmacokinetic model devleoped to identify patient/disease factors affecting adalimumab pharmacokinetics. Impact of immunogenicity on treatment efficacy and safety was also assessed. ResultsWeek 33 mean adalimumab concentration was 5.2 g/mL. Week 16 responders had higher adalimumab concentrations than non-responders (6.3 vs. 2.2 g/mL). Bodyweight and study were significant covariates in population pharmacokinetic model with weight accounting for 19% and 29% of variability in adalimumab clearance and volume of distribution, respectively. A total of 8.8% of adalimumab-treated patients tested AAA positive and had twofold higher adalimumab clearance. PASI 75 response rate was comparable between AAA+ and AAA- patients at Weeks 33 and 52 (Week 33: 36% vs. 22.5%, Week 52: 21.1% vs. 17.8%) and adverse events incidence was similar between the two groups. ConclusionsPatient weight and study significantly affect adalimumab clearance and volume of distribution in psoriasis patients. Development of AAAs result in lower adalimumab exposure and efficacy with no effect on adverse events incidence.