title: Assessment of inhibitory antibodies in patients with hereditary angioedema treated with plasma-derived C1 inhibitor.
abstract: Limited data are available regarding C1 inhibitor (C1-INH) administration and anti-C1-INH antibodies.
  
  
  
  To assess the incidence of antibody formation during treatment with pasteurized, nanofiltered plasma-derived C1-INH (pnfC1-INH) in patients with hereditary angioedema with C1-INH deficiency (C1-INH-HAE) and the comparative efficacy of pnfC1-INH in patients with and without antibodies.
  
  
  
  In this multicenter, open-label study, patients with C1-INH-HAE (≥12 years of age) were given 20 IU/kg of pnfC1-INH per HAE attack that required treatment and followed up for 9 months. Blood samples were taken at baseline (day of first attack) and months 3, 6, and 9 and analyzed for inhibitory anti-C1-INH antibody (iC1-INH-Ab) and noninhibitory anti-C1-INH antibodies (niC1-INH-Abs).
  
  
  
  The study included 46 patients (69.6% female; mean age, 38.9 years; all white) who received 221 on-site pnfC1-INH infusions; most patients received 6 or fewer infusions. No patient tested positive (titer ≥1:50) for iC1-INH-Ab at any time during the study. Thirteen patients (28.2%) had detectable niC1-INH-Abs in 1 or more samples. Nine patients (19.6%) had detectable niC1-INH-Abs at baseline; 3 of these had no detectable antibodies after baseline. Of 10 patients (21.7%) with 1 or more detectable result for niC1-INH-Abs after baseline, 6 had detectable niC1-INH-Abs at baseline. Mean times to symptom relief onset and complete symptom resolution per patient were similar for those with or without anti-niC1-INH-Abs.
  
  
  
  Administration of pnfC1-INH was not associated with iC1-INH-Ab formation in this population. Noninhibitory antibodies were detected in some patients but fluctuated during the study independently of pnfC1-INH administration and appeared to have no effect on pnfC1-INH efficacy.
  
  
  
  clinicaltrials.gov Identifier: NCT01467947.
authors: Semmelweis University, Budapest, Hungary.
authors: Henriette
authors: H
authors: Farkas
authors: Semmelweis University, Budapest, Hungary.
authors: Lilian
authors: L
authors: Varga
authors: University of Medicine and Pharmacy Tîrgu-Mureş, Romania.
authors: Dumitru
authors: D
authors: Moldovan
authors: Jagiellonian University, Krakow, Poland.
authors: Krystyna
authors: K
authors: Obtulowicz
authors: MHAT "TsaritsaYoanna - ISUL", Sofia, Bulgaria.
authors: Todor
authors: T
authors: Shirov
authors: CSL Behring, Marburg, Germany.
authors: Thomas
authors: T
authors: Machnig
authors: CSL Behring, Marburg, Germany.
authors: Henrike
authors: H
authors: Feuersenger
authors: CSL Behring, King of Prussia, Pennsylvania.
authors: Jonathan
authors: J
authors: Edelman
authors: CSL Behring, King of Prussia, Pennsylvania.
authors: Debora
authors: D
authors: Williams-Herman
authors: CSL Behring, King of Prussia, Pennsylvania. Electronic address: mikhail.rojavin@cslbehring.com.
authors: Mikhail
authors: M
authors: Rojavin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D054179:Angioedemas, Hereditary / Q000097:blood* / Q000188:drug therapy* / Q000276:immunology; D000906:Antibodies / Q000097:blood*; D050718:Complement C1 Inhibitor Protein / Q000627:therapeutic use*; D051056:Complement Inactivating Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000906:Antibodies; D050718:Complement C1 Inhibitor Protein; D051056:Complement Inactivating Agents