Immunotherapy using sublingual tablets containing house dust mite allergen extended the interval until patients developed a moderate asthma exacerbation in a manufacturer-sponsored clinical trial reported online April 26 in JAMA.
However, patients’ scores on both the Asthma Control Questionnaire and the Asthma Quality of Life Questionnaire showed no difference between active treatment and placebo. And 25%-27% of the study participants dropped out of the study, usually citing asthma exacerbations, adverse events, or “withdrawal of consent.” Further studies are needed to assess long-term efficacy and safety, said Dr. J. Christian Virchow of the department of pulmonology/intensive care medicine, University of Rostock (Germany), and his associates.
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The trial, involving 834 adults with asthma related to house dust mite allergy that was not well controlled by inhaled corticosteroids and short-acting beta-agonists, was performed at 109 sites in 13 European countries during a 2-year period. These participants were randomly assigned to receive add-on daily sublingual tablets containing low-dose dust-mite extract (275 patients), high-dose extract (282 patients), or placebo (277 patients) for 7-12 months. During the final 6 months of the intervention, corticosteroids were reduced by half for 3 months and then withdrawn for 3 months.
The primary efficacy outcome (time to the first asthma exacerbation) was extended by both doses of active drug, compared with placebo, with hazard ratios of 0.69 for the lower dose and 0.66 for the higher dose, the investigators said (JAMA. 2016 Apr 26;315[16]:1715-25).
Adverse events were significantly more frequent with active treatment, affecting 39% of patients receiving the lower dose and 46% of those receiving the higher dose of active immunotherapy, compared with only 17% of patients receiving placebo. However, this study was not adequately powered to compare adverse events across groups, Dr. Virchow and his associates noted.
The most frequently reported adverse events were oral pruritus, mouth edema, and throat irritation, which developed within a median of 1-2 minutes of taking the first dose on day 1 and persisted for a median of 4-23 days. There were 32 serious adverse events, including erosive esophagitis, hepatocellular injury, arthralgia, laryngeal edema, and asthma.
This trial was limited in that treatment duration was much shorter than that for a standard course of immunotherapy, which is often 3 years. This prevents drawing conclusions regarding the sustained effect of the treatment. “Furthermore, because the ultimate aim of allergen immunotherapy is disease modification beyond the duration of treatment, a follow-up after the end of treatment would have been relevant,” the investigators said.
This study was sponsored by the Danish pharmaceutical company ALK. Dr. Virchow reported ties to 31 industry sources; his associates also reported ties to numerous industry sources.