House dust mite sublingual immunotherapy is safe in patients with mild-to-moderate, persistent asthma: a clinical trial

Background The safety of allergen immunotherapy (AIT) in asthma has not always been sufficiently documented; accordingly, fear of asthma exacerbations has made physicians somewhat reluctant to prescribe AIT in this context. In a double-blind, placebo-controlled, randomized clinical trial, house dust mite (HDM) sublingual AIT was found to be efficacious in moderate, persistent asthma. The trial's safety results are now reported in detail. Methods Asthmatic adults were randomized 2 : 1 to twelve months of daily treatment with a sublingual solution of Dermatophagoides pteronyssinus and Dermatophagoides farinae extracts or a placebo. Adverse events (AEs) at least possibly related to the investigational product were classified by the investigators as adverse drug reactions (ADRs). Results Overall, the patients in the safety analysis set (n = 484; active treatment: n = 322; placebo: n = 162) had mostly well-controlled, persistent asthma [mild in 290 patients (59.9%), moderate in 183 (37.8%) and severe in 11 (2.3%)]. No treatment-related serious AEs were reported. A total of 87.0% and 75.9% of the patients in the active and placebo groups, respectively, experienced at least one AE (mostly mild), and 78.9% and 48.1% experienced an ADR (mostly mild or moderate oral reactions). The incidence of asthma exacerbations (symptoms requiring a short course of oral corticosteroids) during the study was similar in the active treatment group (3.7%) and the placebo group (4.3%). There were no significant intergroup differences or intragroup changes over time in respiratory AEs, lung function or asthma-related quality of life. Conclusions HDM sublingual AIT was safe and well tolerated in adult patients with mild-to-moderate, persistent asthma (ClinicalTrials.gov: NCT00660452).