Prescribing Asthma Controller Medication According to Gene Status to Improve Quality of Life in Young People With Asthma

Asthma is a common chronic illness in children and young people. It affects, for example, an average of two children in every UK classroom. Initial treatment usually consists of salbutamol used on demand at step 1 of British Thoracic Society (BTS) guidelines. At step 2, regular anti-inflammatory 'controller' therapy starts with the regular use of inhaled corticosteroids such as beclomethasone. Therapeutic efficacy with inhaled steroids usually peaks around 400 micrograms per day of beclomethasone (or equivalent). With inadequate asthma control at step 2, inhaled long-acting β2 agonists (LABA) such as salmeterol, or leukotriene receptor antagonists (LTRA) such as montelukast are added; this represents BTS step 3 for asthma management.

The improvement of asthma-related quality-of-life represents an important goal for the overall pharmacological management of asthma. Juniper has developed and validated questionnaires for the measurement of asthma-related quality-of-life and asthma control in both children and adults. Furthermore, Juniper has defined the minimum improvement in asthma-related quality-of-life that is clinically relevant for participants with this disease. In addition, Juniper has recently validated on-line versions of the asthma-related quality-of-life and asthma control questionnaires in children aged 12 and above. This could provide an opportunity for more long-term and cost-effective comparisons of different asthma treatments through the use of tools that measure asthma control without the need for clinic visits and the completion of paper-based forms.

Overall, in children with asthma managed on step 3, salmeterol appears to provide better asthma control than montelukast in the setting of a randomized controlled trial. However, in real life, the efficacy of salmeterol at step 3 for improving asthma control in individual children appears rather variable, and some children continue to experience day-to-day symptoms and exacerbations.

The investigators showed in a earlier study of 1182 UK children and young adults (4-22 years), 50% of those on regular salmeterol experienced asthma exacerbations over a 6-month period, and 18% required inhaled salbutamol at least daily for symptom relief. A step-wise increase was reported in the risk of asthma attacks related to each copy of the Arg16 allele on the β2 receptor gene (1.7-fold) in asthmatic children and young adults exposed to regular salmeterol in conjunction with inhaled corticosteroids. This led the investigators to hypothesize that, contrary to the observations on the overall population of children and young adults where salmeterol is superior in efficacy to montelukast at step 3, those possessing susceptible Arg16 β2 receptor genotype may experience better asthma control with the addition of montelukast rather than salmeterol as second-line controller medication, in addition to inhaled corticosteroids. As such the investigators elected to identify from their database those children with two copies of the Arg16 polymorphism [i.e. homozygous Arg genotype (∼15% of overall population) who would potentially be at greatest risk]. The mechanism for worse control with regular salmeterol involves a greater susceptibility to agonist-induced down-regulation and uncoupling of airway β2 receptors and associated sub-sensitivity of response in the Arg16 genotype.

The investigators therefore performed a proof-of-concept randomized controlled trial to determine whether genetically susceptible children with homozygous Arg16 genotype experience superior long-term asthma control with montelukast compared with salmeterol when used as tailored second-line controller therapy as add-on to the inhaled steroid fluticasone. The purpose of this preliminary study was to provide evidence to support the potential for personalised medicine based on the individual genotype to improve asthma-related quality-of-life and control. This study was published in 2013, and represents the first prospective randomized controlled study in children with asthma that addresses personalised medicine based on genotype. The results of this study showed that in children expressing the homozygous Arg 16 genotype, in comparison with salmeterol, adding montelukast to inhaled fluticasone significantly improved asthma-related quality-of-life and clinical symptoms, while reducing school absences and inhaled reliever use. The relative benefits of montelukast in comparison with salmeterol became evident within the first 3 months and persisted throughout the whole year.

Subsequently, the investigators systematically searched for other randomised controlled trials comparing the effects of salmeterol (or other long-acting beta2 agonist) with montelukast (or other leukotriene antagonist) within the context of Arg/Gly variation, in children with asthma. No studies could be identified. In particular, there were no trials in either adults or children that have studied quality-of-life, which is a key outcome of interest in the context of asthma-related disability, and which is often unrelated to outcomes such as lung function. The absence of other randomised trials, together with the strength of the investigators proof-of-concept evidence, underscores the need for this powered study.

Rationale:

Children with asthma inadequately controlled on inhaled steroids as 'controller' medication experience greater benefit in asthma-related quality-of-life from allocation of further drug therapy on the basis of their genetic status, in comparison to allocation on the basis of current method of doctor or nurse choice informed by the BTS guidelines.

Primary Objective:

Does the prescribing of asthma controller medication according to beta2 receptor gene status improve quality of life as determined by validated questionnaire (Juniper) in 12-18 year olds with asthma?

Secondary Objectives:

Asthma control, as determined by validated questionnaire 3, 6, 9 and 12 months and an evaluation of how many visits participants report to have attended their General Practitioner (GP) or asthma nurse (non- routine asthma review), A\&E or been hospitalised as a result of their asthma . Courses of oral steroids and any other medication taken will also be recorded.