Current asthma therapies can effectively control symptoms and the ongoing inflammatory process but do not affect the underlying dysregulated immune response. Thus they are very limited in controlling the progression of the disease. Immunotherapy can make some difference in the treatment of asthma allergy.
Few specifically designed studies evaluated allergy immunotherapy in asthmatic patients, and only 1 had a formal sample size calculation. In addition, no consensus exists on the optimal end points, with pulmonary function or asthma exacerbations or control assessed as the primary outcome only sporadically. Several double-blind, placebo-controlled trials and meta-analysis (potentially hampered by the heterogeneity of the trials included) have confirmed that both subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) are of value in patients with allergic asthma associated with allergic rhinitis. An effectiveness and safety reviewconducted by the US Food and Drug Administration showed moderate to high (somewhat weaker in children) evidence for the efficacy of both SCIT and SLIT in asthmatic patients, with weak evidence for assessing the superiority of either route. One Cochrane review reported a significant reduction in symptom scores, medication use, and allergen-specific airway hyperreactivity and a limited reduction in nonspecific airway hyperreactivity. The effects on lung function were not consistent among trials. The most recent systematic review up to May 2013 concluded that SCIT significantly reduces asthma symptoms and medication use. Because most of the published evidence for SLIT comes from studies primarily in patients with rhinitis, they are not adequately powered. A systematic review on SLIT reports strong evidence for improvement in asthma symptoms versus the comparator but only moderate evidence for a decrease in use of asthma medication.
A potential steroid-sparing effect of allergy immunotherapy is of utmost importance to avoid the potential side effects of inhaled corticosteroids in asthmatic patients. For both SCIT and SLIT, a reduction of the inhaled corticosteroid dose needed to maintain asthma control was demonstrated.
Ongoing phase 3 confirmatory double-blind, placebocontrolled trials with both SCIT and SLIT in patients with perennial HDM allergic asthma will provide more robust evidence (data from ClinicalTrials.gov, EU Clinical Trials Register, Japan Pharmaceutical Information Center: Clinical Trials Information).
More and more progress will be made in the immunotherapy for asthma allergy.
Jutel M et al. International consensus on allergy immunotherapy[J]. Journal of Allergy and Clinical Immunology, 2015, 136(3): 556-568.