A phase III study to assess the efficacy and safety of sublingual immunotherapy with STALORAL dust mites solution compared with placebo for reduction of asthma symptoms.

Inclusion Criteria:

1. Male or female outpatients aged 16 to 50 years (inclusive).
2. House dust mite-induced allergic asthma with or without perennial allergic rhinitis for at least 1 year.
3. Sensitised to D. pteronyssinus and D.farinae (positive skin prick test (SPT) with wheal diameter ≥ 4 mm and specific IgE level ≥ 0.70 kU/L
4. Patients treated with inhaled corticosteroids (ICS) before the screening visit at a dose ≥ 200 µg and < 1,000 µg equivalent budesonide/day.

Exclusion Criteria:

1. Mild intermittent asthma needed to be treated only with β2-agonist (GINA level 1).
2. Severe asthma needed to be treated with inhaled corticosteroids with a dose ≥ 1,000 µg/day equivalent budesonide.
3. FEV1 < 70% of predicted value at Visit 1.
4. Co-sensitisation to other inhalant allergens than dust mites leading to clinically relevant allergic asthma and proven by a positive skin prick test with wheal diameter ≥ 4 mm and serum specific IgE ≥ 0.70 KU/L .
5. Patients with a past or current disease, which as judged by the investigator, may affect the patient's participation in or the outcome of the study. These diseases include, but are not limited to, past or current cardiovascular disease, malignancy, hepatic disease, renal disease, haematological disease, neurological disease, immunological disease and endocrine disease.