Dose Ranging Study of SLIT Tablets of House Dust Mite Allergen Extracts (HDM) in Adults With HDM-associated Allergic Asthma

Inclusion Criteria: * Written informed consent. * Male or female from 18 to 50 years of age. * Diagnosed asthma and rhinitis with medical history consistent with HDM-induced allergic asthma and rhinitis. * Positive SPT to HDM and and HDM-specific IgE serum value ≥ 0.7 kU/L. * Stable asthma therapies. * Spirometry (pre-bronchodilator) with best FEV1 ≥ 70% of the predicted value. * Spirometry with reversibility in FEV1 of ≥ 12% and ≥ 200 mL. * Asthma Control Test™ (ACT) score ≤ 19. Exclusion Criteria: * Former smoker with \> 10 pack year history or current smoker. * Patient with a urine level of cotinine ≥ 500 ng/mL. * Co-sensitisation to any allergen possibly leading to clinically relevant symptoms likely to significantly change the asthma symptoms of the subject during the study. * Patient who received allergen immunotherapy for HDM within the past 10 years. * Ongoing immunotherapy for an aeroallergen other than house dust mite. * Patient with any oral condition that could confound the safety assessments or planning to have a dental extraction during the study. * Patient treated with beta-blockers, tricyclic antidepressants or monoamine oxidase inhibitors (MAOIs). * Pregnant women or breast-feeding/lactating. * Women with childbearing potential who are not using a medically accepted birth control method. * Patient with a past or current disease, which as judged by the Investigator, may affect the patient's participation in, or the outcome of this study.