Data Suggests Efficacy Of Advair, Serevent Is Not Impacted By Genetic Profile
Data presented by GlaxoSmithKline showed that genetic differences at the site of the beta-2 adrenergic receptor gene in asthma patients did not lead to different responses to Advair Diskus (fluticasone propionate and salmeterol inhalation powder) or Serevent Diskus (salmeterol xinofoate inhalation powder).
Past prospective clinical trials have found that the use of short-acting beta-agonists, such as albuterol, were linked to worse outcomes in patients with asthma with the Arg/Arg genotype of the beta-2 adrenergic receptor gene. In the research presented today, those patients with the Arg/Arg profile responded to Advair (the combination of an inhaled corticosteroid and a long-acting beta-agonist) or Serevent (a long-acting beta-agonist) treatment as well as those patients with the two other forms of the gene (Arg/Gly and Gly/Gly).
The data (abstract #554) was presented by Eugene R. Bleecker, M.D., a professor of medicine and co-director of the Center for Human Genomics at the Wake Forest University School of Medicine at the 2008 American Academy of Allergy, Asthma and Immunology annual meeting in Philadelphia.
"This study was the largest prospective study of the impact of genetic differences in the beta-2 adrenergic receptor on response to asthma therapy, and we were encouraged to see that patients with the Arg/Arg gene variation responded to Advair and Serevent therapy just as well as patients without that variation," said Dr. Bleecker. "This study is a large step forward in furthering our knowledge of the interplay between genetics and therapy in asthma."
The 544-patient trial evaluated three groups of patients: those with the Arg/Arg genotype, those with the Arg/Gly genotype and those with the Gly/Gly genotype. Patients were treated for 16 weeks with either Advair or Serevent.
The results showed that there was no significant difference between any of the three genotype groups for the primary endpoint, morning peak expiratory flow rate, and all genotype groups showed sustained improvement on treatment with Advair or Serevent. There was also no difference between the improvement recorded for each of the three groups on the secondary endpoints of forced expiratory volume in 1 second (FEV1), symptom-free days or use of a rescue inhaler.
A sub-analysis of that trial was also presented today at the AAAAI meeting (abstract #509) by Harold Nelson, M.D., professor of medicine at National Jewish Medical and Research Center in Denver. Dr. Nelson's analysis found that the incidence of asthma exacerbations, defined as worsening asthma requiring ED-visit/hospitalization or any medication beyond protocol, did not differ by genetic profile, further suggesting that having a genetic variation in the beta-2 adrenergic receptor does not have an effect on response to Advair or Serevent.
Further research on the same group of patients (abstract #552) was also presented, examining more closely any link between genetic differences in the beta-2 adrenergic receptor gene and response to therapy. That trial looked at 11 different genetic polymorphisms or haplotypes on that gene and found that no single variation was associated with a differential response to Advair or Serevent.
Advair Diskus combines two medications in one device to help prevent and control asthma symptoms. Asthma causes inflammation (swelling in the airways) and airway constriction (the tightening of muscles that surround the airways), and Advair contains both an inhaled corticosteroid, fluticasone propionate, to reduce inflammation; and an inhaled long-acting bronchodilator, salmeterol, to help prevent and reduce airway constriction. Advair is for people who still have symptoms on another asthma controller, or whose disease severity clearly warrants treatment with two maintenance therapies.