title: Determination of adalimumab and etanercept trough levels and drug antibodies in long-term psoriasis treatment: a single-centre cohort study.
abstract: BACKGROUND
  An algorithm based on measurement of a serum tumour necrosis factor antagonists (anti-TNF) and antidrug antibodies (ADA) has been proposed previously to guide dose escalation or therapy switching in the early (i.e. the first months of) treatment of psoriasis by anti-TNF. In long-term treatment of responding patients with psoriasis, it is usual to empirically reduce standard doses of anti-TNF to reduce exposure while maintaining clinical response. The relationship between serum anti-TNF, ADA levels and clinical efficacy in long-term treated patients with psoriasis has not yet been determined, so the potential role of these parameters in guiding dose escalation in this scenario is unknown.
  
  
  OBJECTIVE
  To evaluate the relationship between drug/ADA levels and clinical efficacy in a group of patients with psoriasis undergoing long-term treatment with adalimumab or etanercept.
  
  
  METHODS
  This was a single-centre, prospective, cohort study of patients with psoriasis receiving adalimumab or etanercept for a minimum of 48 weeks. All patients were started on the standard dose, but some adalimumab users had a reduced frequency of administration. Clinical efficacy was measured using the Psoriasis Area and Severity Index. Serum concentrations were measured by ELISA. Clinical assessment and blood sample collection were carried out simultaneously within 24 h before the next drug administration.
  
  
  RESULTS
  In total, 21 patients were enrolled (67 simultaneous clinical and serum determinations: 38 receiving adalimumab, 29 receiving etanercept). We did not find any association between serum anti-TNF levels and clinical response. None of the patients developed ADA.
  
  
  CONCLUSIONS
  ADA and anti-TNF levels are not related to clinical effectiveness in patients with psoriasis undergoing long-term treatment with adalimumab or etanercept.
authors.affiliation: Department of Dermatology, Pontificia Universidad Catolica de Chile, Santiago, Chile.
authors.forename: J
authors.initials: J
authors.lastname: Manriquez
authors.affiliation: Department of Dermatology, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Alsina-Gibert
mesh_terms: D000068879:Adalimumab / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics*; D000328:Adult; D000368:Aged; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics; D000906:Antibodies / Q000276:immunology*; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D000068800:Etanercept / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011565:Psoriasis / Q000188:drug therapy; D013997:Time Factors; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000097:blood*
chemical_list: D000893:Anti-Inflammatory Agents; D000906:Antibodies; D007166:Immunosuppressive Agents; D014409:Tumor Necrosis Factor-alpha; D000068879:Adalimumab; D000068800:Etanercept