title: Effect of ADRB2 polymorphisms on response to longacting beta2-agonist therapy: a pharmacogenetic analysis of two randomised studies.
abstract: BACKGROUND
  New evidence has suggested that people with asthma who are homozygous for arginine at aminoacid 16 of the beta2-adrenergic receptor (ADRB2) might not benefit from longacting beta2-agonist therapy. We, therefore, investigated whether ADRB2 polymorphisms affect response to longacting beta2-agonists in combination with inhaled corticosteroids.
  
  
  METHODS
  Asthmatics were stratified by ADRB2 genotype in two studies to assess the effects of inhaled corticosteroids plus longacting beta2-agonists on asthma exacerbations. In study 1 (double-blind), 2250 asthmatics were randomly assigned to budesonide plus formoterol maintenance and reliever therapy, fixed-dose budesonide plus formoterol, or fixed-dose fluticasone plus salmeterol for 6 months. Study 2 (open-label) consisted of 405 asthmatics and compared an adjustable regimen of budesonide plus formoterol with fixed-dose budesonide plus formoterol and fixed-dose fluticasone plus salmeterol for 7 months. The relation between ADRB2 polymorphism, severe asthma exacerbations, and other asthma outcomes was analysed. Primary endpoints for studies 1 and 2 were severe asthma exacerbation and asthma control as assessed by measures of exacerbations, respectively.
  
  
  RESULTS
  In study 1, Gly16Arg genotype had no effect on the percentage of participants with severe exacerbations across all treatment groups (99 [12%] of 833 Gly/Gly, 110 [11%] of 1028 Gly/Arg, and 32 [9%] of 361 Arg/Arg participants). Secondary endpoints, including forced expiratory volume in 1 s, peak expiratory flow, use of as-needed medication, and number of nights with awakenings were similar between genotype groups. No relation was recorded between ADRB2 haplotype and primary and secondary endpoints. In study 2, the frequency of asthma exacerbations (15 [9%] of 168 Gly/Gly, 13 [8%] of 169 Gly/Arg, and 6 [9%] of 67 Arg/Arg participants) and other study endpoints were closely similar for all ADRB2 genotypes.
  
  
  CONCLUSIONS
  Since we showed no pharmacogenetic effect of ADRB2 variation on therapeutic response in asthma, patients, irrespective of their genotype, can continue to receive inhaled corticosteroids plus longacting beta2-agonists.
authors.affiliation: Center for Human Genomics, Wake Forest University School of Medicine, Winston-Salem, NC, USA. ebleeck@wfubmc.edu
authors.forename: Eugene R
authors.initials: ER
authors.lastname: Bleecker
authors.forename: Dirkje S
authors.initials: DS
authors.lastname: Postma
authors.forename: Rachael M
authors.initials: RM
authors.lastname: Lawrance
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Meyers
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Ambrose
authors.forename: Mitch
authors.initials: M
authors.lastname: Goldman
mesh_terms: D000318:Adrenergic beta-Agonists / Q000009:adverse effects / Q000627:therapeutic use; D000328:Adult; D000420:Albuterol / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000235:genetics; D019819:Budesonide / Q000009:adverse effects / Q000627:therapeutic use; D004983:Ethanolamines / Q000009:adverse effects / Q000627:therapeutic use; D005260:Female; D000068759:Formoterol Fumarate; D005838:Genotype; D006801:Humans; D008297:Male; D010366:Peak Expiratory Flow Rate / Q000187:drug effects; D010597:Pharmacogenetics; D011110:Polymorphism, Genetic; D016032:Randomized Controlled Trials as Topic; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics*; D000068299:Salmeterol Xinafoate
chemical_list: D000318:Adrenergic beta-Agonists; D004983:Ethanolamines; D018343:Receptors, Adrenergic, beta-2; D019819:Budesonide; D000068299:Salmeterol Xinafoate; D000420:Albuterol; D000068759:Formoterol Fumarate