Immunotherapy Tablet for House Dust Mite Allergy Reduces Exacerbations

A house dust mite sublingual allergen immunotherapy (SLIT) may be a potential novel treatment option for this allergy–related asthma, according to a new study.

Persistent symptoms are common in many patients with house dust mite allergic disease, and treatment options include inhaled corticosteroids (ICS) and long-acting beta-agonists. Up to 30% of patients, however, remain symptomatic, uncontrolled, or both despite treatment, and uncontrolled asthma is a major risk factor for future exacerbations and poorer clinical outcomes, state the authors, led by J. Christian Virchow, MD, of the University of Rostock, Germany.

The house dust mite SLIT has previously proven to be effective in reducing the requirement for ICS and in reducing allergic rhinitis symptoms and need for pharmacotherapy among patients with house dust mite respiratory allergic disease, but has not been tested for its effect on risk of asthma exacerbations.

Virchow and colleagues investigated the efficacy of the SLIT among patients with house dust mite allergy–related asthma that was not well controlled by ICS, and with house dust mite allergy–related rhinitis. They reported their results April 26, 2016 in the Journal of the American Medical Association.

The double-blind, randomized, placebo-controlled trial in 109 European sites included 834 adults, mean age 33 years. They received once-daily treatment with lower-dose house dust mite SLIT (275 patients), higher-dose house dust mite SLIT (282 patients), or placebo (277 patients), in addition to ICS and the short-acting beta₂-agonist salbutamol. The primary objective was to evaluate efficacy measured by reducing the risk for an asthma exacerbation during a 6-month ICS reduction period.

Of the 693 patients who completed the study, both the lower and higher SLIT doses significantly reduced the risk of a moderate or severe asthma exacerbation compared with placebo. The absolute risk of first exacerbation was 26% for the lower dose group, 24% for the higher dose group, and 32% for the placebo group, primarily involving moderate rather than severe exacerbations. There was no significant difference between the two active treatment groups.

Mild to moderate adverse reactions were common. Mild to moderate oral pruritus occurred in 13% in the lower dose group and 20% in the higher dose group. There were no reports of severe systemic allergic reactions.

In conclusion, the researchers stated that “among adults with house dust mite allergy–related asthma not well controlled by ICS, the addition of house dust mite SLIT to maintenance medications improved time to first moderate or severe asthma exacerbation during ICS reduction, with an estimated absolute reduction at 6 months of 9 to 10 percentage points; the reduction was primarily due to an effect on moderate exacerbations.”

They noted that further studies are needed to assess long-term efficacy and safety.

The trial has limitations, they acknowledged. The establishment of a baseline and twice-daily diary recordings will have limited usability in clinical practice. Also, the trial had a shorter duration than a standard course of immunotherapy, which often is 3 years, did not include a follow-up of disease-modification afterward, and was not powered to assess a comparison of adverse events.

Source:

Virchow JC, Backer V, Kuna P, et al. Efficacy of a house dust mite sublingual allergen immunotherapy tablet in adults with allergic asthma: a randomized clinical trial. JAMA. 2016 Apr 26;315:1715-25. doi: 10.1001/jama.2016.3964.