9 January 2013
An inexpensive genetic test could identify which childhood asthma sufferers are unlikely to benefit from a common treatment and would experience better outcomes using an alternative, new research suggests.
The study published in Clinical Science looked at 62 children with a particular variant of the beta-2 adrenergic receptor gene that is carried by around one in seven asthma sufferers. The researchers had shown in previous work that those with the variant are usually unresponsive to the drug salmeterol, which is taken as a ‘second-line’ therapy by children whose asthma cannot be controlled with the standard blue inhaler. Salmeterol is ineffective for them because the variant alters the shape of the beta-2 receptors that the drug acts upon.
Half of the children in the study were given salmeterol, and half an alternative asthma drug, montelukast for one year. The effectiveness of the treatments was measured by comparing school absence rates between the two groups, as well as their reported symptoms and quality of life. The study found that montelukast was associated with better outcomes, and concludes that it may be a more suitable second-line therapy for children with the variant. Lead author of the study, Professor Somnath Mukhopadhyay, said "We've shown for the first time that personalised medicine can work in the field of childhood asthma".
Comment: This was a small study, but one with potentially large implications. Since patients who have the variant could be identified via a simple ‘spit test’ costing around £15, it could be a very cost-effective way to allocate asthma sufferers the best treatment. The work would need to be replicated robustly and on a much larger scale before incorporating its findings into clinical guidelines though. One possible area of weakness of the study is that a primary indicator for response to treatment was school absence rates, which may not necessarily accurately reflect severity of symptoms or efficacy of treatment.