Allergen immunotherapy (AIT) is an important treatment in patients with house dust mite (HDM)-driven allergic asthma. The available research has mainly focused on sublingual AIT for D. pteronyssinus and D. farinae. However, the expected effects of such treatment are not always obtained and are dependent on many factors. Moreover, there has been some evidence that the addition of omalizumab for desensitization may enhance the effects of AIT. However, these observations have not been completely confirmed.

The aim of the study was to present the effectiveness of treatment with Purethal mites in combination with or without omalizumab (compared to a placebo treatment) in patients with HDM-driven allergic asthma.

This double-blind, placebo-controlled trial was conducted with 43 patients with HDM-driven asthma who were individually randomized in comparable numbers to one of three parallel groups: 12-month perennial AIT with the use of Purethal Mites or Purethal Mites and omalizumab or placebo. The following parameters were analysed: total asthma symptom score (TASS), combined total symptom score (TSS), total medication score (TMS) and mean serum concentrations of allergen-specific IgG4 to D. pteronyssinus and D. farinae and Der p1 and Der p2. Purethal was administered on a standard, perennial therapy protocol. Omalizuab was administered as follows: an initial dose of 150 mg every two weeks; after 6 weeks, 150 mg monthly doses for the rest of the year.

Fourteen patients after Purethal treatment, 12 patients after the combined Purethal and omalizumab therapy treatment and 13 placebo treatment subjects who completed the study protocol were included in the final analysis. Significant reductions in TASS during 12 months of treatment were observed in patients after therapy with Purethal (from 4.08±1.65 to 1.71±0.55, p<0.05) and after therapy with Purethal+omalizumab (from 4.34±2.01 to 0.97±0.44, p<0.05), in comparison to the placebo group (from 4.76±1.44 to 3.82± 1.77, p>0.05). However, TASS was observed to be more significantly decreased in patients with combined therapy than in those patients who received only Purethal (p<0.05). The other parameters (TSS and TMS) in both groups with the use of Purethal therapy also exhibited significantly decreased levels (p<0.05). Serum-specific IgG4 against D. pteronyssinus, D. farinae, Der p1 and Der p2 were observed to increase during the AIT trial in both groups after Purethal therapy (alone or with omalizumab). 

AIT to HDM allergens was more effective in reducing asthmatic symptoms when omalizumab was added in patients with HDM-driven asthma. Further studies are necessary.