Efficacy and safety of a glutaraldehyde-modified house dust mite extract in allergic rhinitis

Modification of allergens by glutaraldehyde in extracts used for immunotherapy reduces the risk for side effects, but therapeutic efficacy of such extracts requires further evaluation. The aim of this study was to evaluate the efficacy and safety of immunotherapy with PURETHAL Mites (PM), a single-strength glutaraldehyde-modified aluminum hydroxide-adsorbed extract of house-dust mites (HDM).

In a multicenter, randomized, placebo-controlled double-blind setting, HDM-allergic subjects (n = 140) were treated with modified allergen extract or placebo over a 1-year period. The primary outcome parameter was a combined symptom and medication score (clinical index score [CIS]). Secondary efficacy parameters were the result of a titrated conjunctival provocation test (CPT), rhinitis/rhinoconjunctivitis quality of life (RQL) score, and serum concentrations of IgE and IgG against specific HDM allergens and a documentation of adverse events (AE).

We evaluated 140 patients (66 treatment and 74 placebo) for clinical efficacy. The allergoid treatment for 1 year resulted in significantly greater CIS improvement and higher RQL scores. The response threshold in the titrated CPT (p = 0.009) and the serum concentrations of IgG4 (p < 0.001) against Dermatophagoides pteronyssinus allergens after treatment were also significantly different between groups. In total, 88 patients (46 PM/42 placebo) out of a safety population of 145 reported 278 (158 PM/120 placebo) AE. Except for local reactions, no specific AE appeared to be associated with PURETHAL Mites (HAL-Allergy, Leiden, The Netherlands).

The findings of this study indicate that allergen injection therapy with modified HDM extract is superior to placebo in allergic rhinitis therapy. The treatment was well tolerated and no serious drug-related AE were observed.