title: OnabotulinumtoxinA for treatment of chronic migraine: results from the double-blind, randomized, placebo-controlled phase of the PREEMPT 2 trial.
abstract: OBJECTIVE
  This is the second of a pair of studies designed to evaluate the efficacy and safety of onabotulinumtoxinA (BOTOX) for prophylaxis of headaches in adults with chronic migraine.
  
  
  METHODS
  PREEMPT 2 was a phase 3 study, with a 24-week, double-blind, placebo-controlled phase, followed by a 32-week, open-label phase. Subjects were randomized (1:1) to injections of onabotulinumtoxinA (155U-195U; n = 347) or placebo (n = 358) every 12 weeks for two cycles. The primary efficacy endpoint was mean change in headache days per 28 days from baseline to weeks 21-24 post-treatment.
  
  
  RESULTS
  OnabotulinumtoxinA was statistically significantly superior to placebo for the primary endpoint, frequency of headache days per 28 days relative to baseline (-9.0 onabotulinumtoxinA/-6.7 placebo, p < .001). OnabotulinumtoxinA was significantly favoured in all secondary endpoint comparisons. OnabotulinumtoxinA was safe and well tolerated, with few treatment-related adverse events. Few patients (3.5% onabotulinumtoxinA/1.4% placebo) discontinued due to adverse events.
  
  
  CONCLUSIONS
  The results of PREEMPT 2 demonstrate that onabotulinumtoxinA is effective for prophylaxis of headache in adults with chronic migraine. Repeated onabotulinumtoxinA treatments were safe and well tolerated.
authors.affiliation: University of Essen, Germany. hans.diener@uni-duisburg-essen.de
authors.forename: H C
authors.initials: HC
authors.lastname: Diener
authors.forename: D W
authors.initials: DW
authors.lastname: Dodick
authors.forename: S K
authors.initials: SK
authors.lastname: Aurora
authors.forename: C C
authors.initials: CC
authors.lastname: Turkel
authors.forename: R E
authors.initials: RE
authors.lastname: DeGryse
authors.forename: R B
authors.initials: RB
authors.lastname: Lipton
authors.forename: S D
authors.initials: SD
authors.lastname: Silberstein
authors.forename: M F
authors.initials: MF
authors.lastname: Brin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D002908:Chronic Disease; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000188:drug therapy*; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A