Immunotherapy for house-dust mite allergy

Background: Since the discovery of house-dust mites (HDM) in the 1960's, allergy immunotherapy trials that used extracts of these mites have been conducted, first by subcutaneous (SCIT) and later by the sublingual (SLIT) route. When reviewed in 2013, published studies of HDM immunotherapy were found to often be characterized by small sample size, widely varying doses, and poorly defined disease severity and outcomes. These trials were thought to to support the efficacy of HDM subcutaneous allergy immunotherapy but the evidence for efficacy of sublingual immunotherapy was less firm. Methods: This report will review a large number of well-designed studies reported since 2013, mostly of SLIT, and in particular, of two newly developed HDM sublingual tablets. In addition, other aspects of HDM immunotherapy will be addressed, including use in atopic dermatitis, optimum duration of treatment, evidence for disease modification and use with adjuvants. Results: Seventeen reports on 15 randomized, double-blind, placebo-controlled trials were identified as having been published since the cut-off date of the 2013 systematic review. Twelve of these reported results with the 2 HDM SLIT-tablets. These studies clearly established the appropriate doses and the efficacy and safety of these tablets in treating allergic rhinitis and asthma. Other reports offered support for use of HDM immunotherapy in selected patients with atopic dermatitis, for administration of HDM immunotherapy for 3 to 5 years, for anticipating disease modification after 3-5 years of treatment, and for the use of vitamin D and selected probiotics to enhance its efficacy. Conclusion: HDM SCIT and SLIT-tablet therapy have demonstrated effectiveness in allergic rhinitis and asthma. Appropriate dosing with HDM SLIT-liquid has not been established although a limited number of studies suggest it can be effective as well. HDM SCIT and HDM SLIT share efficacy in allergic rhinitis and asthma, disease modification and the duration of treatment required to produce persisting benefit.