title: Antibodies to infliximab and adalimumab in patients with rheumatoid arthritis in clinical remission: a cross-sectional study.
abstract: Objective. To investigate if antibodies towards biological TNF-α inhibitors (anti-TNFi Abs) are present in patients with rheumatoid arthritis (RA) in clinical remission and to relate any anti-TNFi Abs to circulating level of TNF-α inhibitor (TNFi). Methods. Patients with RA, treated with infliximab or adalimumab, and in clinical remission (DAS28(CRP) < 2.6) were included from 6 out-patient clinics. In blood samples, presence of anti-TNFi Abs was determined by radioimmunoassay, and concentration of bioactive TNFi was measured by a cell-based reporter gene assay. Results. Anti-TNFi Abs were present in 8/44 patients (18%) treated with infliximab and 1/49 patients (2%) treated with adalimumab (p = 0.012). In the former group, anti-TNFi Abs corresponded with low levels of TNFi (p = 0.048). Anti-TNFi Ab-positive patients had shorter disease duration at initiation of TNFi therapy (p = 0.023) but were similar for the rest of the compared parameters. Conclusions. In RA patients in clinical remission, anti-TNFi Abs occur frequently in patients treated with infliximab, while they occur rarely in patients treated with adalimumab. Presence of anti-infliximab Abs is accompanied by low or undetectable levels of infliximab. These data suggest that continued infliximab treatment may be redundant in a proportion of RA patients treated with infliximab and in clinical remission.
authors.affiliation: Department of Clinical Biochemistry, Copenhagen University Hospital at Køge, 4600 Køge, Denmark ; Department of Rheumatology, Copenhagen University Hospital at Køge, 4600 Køge, Denmark ; The Parker Institute, Department of Rheumatology, Copenhagen University Hospitals at Frederiksberg and Bispebjerg, 2000 Copenhagen F, Denmark.
authors.forename: Grith P
authors.initials: GP
authors.lastname: Eng
authors.affiliation: Institute for Inflammation Research (IIR), Rigshospitalet University Hospital, 2100 Copenhagen, Denmark.
authors.forename: Klaus
authors.initials: K
authors.lastname: Bendtzen
authors.affiliation: The Parker Institute, Department of Rheumatology, Copenhagen University Hospitals at Frederiksberg and Bispebjerg, 2000 Copenhagen F, Denmark.
authors.forename: Henning
authors.identifier: 0000-0002-7951-1668
authors.initials: H
authors.lastname: Bliddal
authors.affiliation: Department of Rheumatology, Copenhagen University Hospital at Køge, 4600 Køge, Denmark ; DANBIO registry, Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, 2600 Glostrup, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Stoltenberg
authors.affiliation: Department of Rheumatology, Copenhagen University Hospital at Køge, 4600 Køge, Denmark.
authors.forename: Marcin
authors.initials: M
authors.lastname: Szkudlarek
authors.affiliation: Department of Rheumatology, Copenhagen University Hospital Glostrup, 2600 Glostrup, Denmark.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Fana
authors.affiliation: Department of Rheumatology, Odense University Hospital, 5000 Odense, Denmark.
authors.forename: Hanne M
authors.initials: HM
authors.lastname: Lindegaard
authors.affiliation: Department of Rheumatology, Copenhagen University Hospitals at Frederiksberg and Bispebjerg, 2000 Frederiksberg, Denmark.
authors.forename: Emina
authors.initials: E
authors.lastname: Omerovic
authors.affiliation: Department of Rheumatology, Copenhagen University Hospital at Gentofte, 2900 Gentofte, Denmark.
authors.forename: Pil
authors.initials: P
authors.lastname: Højgaard
authors.affiliation: Department of Rheumatology, Copenhagen University Hospital at Holbæk, 4300 Holbæk, Denmark.
authors.forename: Elmo K
authors.initials: EK
authors.lastname: Jensen
authors.affiliation: Department of Clinical Biochemistry, Copenhagen University Hospital at Køge, 4600 Køge, Denmark.
authors.forename: Pierre N
authors.initials: PN
authors.lastname: Bouchelouche