title: A retrospective study of serum KL-6 levels during treatment with biological disease-modifying antirheumatic drugs in rheumatoid arthritis patients: a report from the Ad Hoc Committee for Safety of Biological DMARDs of the Japan College of Rheumatology.
abstract: OBJECTIVE
  We investigated associations between treatment with methotrexate (MTX) or biological disease-modifying antirheumatic drugs (DMARDs) and elevation of serum Krebs von den Lungen-6 (KL-6) levels in Japanese patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Using a standardized form, data were collected retrospectively from medical records and analyzed descriptively.
  
  
  RESULTS
  Of a total of 198 RA patients with KL-6 serum levels measured at initiation of treatment (month 0) and two or more times by month 12, 27 (17.9 %) of 151 RA patients treated with biological DMARDs, including infliximab, etanercept, adalimumab, and tocilizumab (the biological DMARDs group), and 5 (10.6 %) of 47 patients treated without biological DMARDs but with MTX (MTX group), met criterion B (max. KL-6 ≥500 U/ml and >1.5-fold from baseline) by 12 months. The majority of patients (n = 28) meeting criterion B had no apparent interstitial lung disease or malignancy. Of these 28 patients, 21 had serum KL-6 levels available after reaching their maximum level, and 13 (61.9 %) of the 21 then met criterion R [decrease to less than 500 U/ml or to less than (baseline + 0.5 × (maximum - baseline))] by month 12.
  
  
  CONCLUSIONS
  Serum KL-6 levels may increase during treatment with MTX or these biological DMARDs without significant clinical events.
authors.affiliation: Department of Medicine and Rheumatology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Akito
authors.initials: A
authors.lastname: Takamura
authors.forename: Shintaro
authors.initials: S
authors.lastname: Hirata
authors.forename: Hayato
authors.initials: H
authors.lastname: Nagasawa
authors.forename: Hideto
authors.initials: H
authors.lastname: Kameda
authors.forename: Yohei
authors.initials: Y
authors.lastname: Seto
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Atsumi
authors.forename: Makoto
authors.initials: M
authors.lastname: Dohi
authors.forename: Takao
authors.initials: T
authors.lastname: Koike
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Miyasaka
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Harigai
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000188:drug therapy*; D001688:Biological Products / Q000009:adverse effects / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008727:Methotrexate / Q000009:adverse effects / Q000627:therapeutic use; D008875:Middle Aged; D018396:Mucin-1 / Q000097:blood*; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D018501:Antirheumatic Agents; D001688:Biological Products; C060192:MUC1 protein, human; D018396:Mucin-1; D008727:Methotrexate