Safety Study of Sublingual Immunotherapy Tablets of House Dust Mite Allergen Extracts in Adolescents

Inclusion Criteria: * Written informed consent from patient and parent(s)/legal representative. * Male or female patient from 12 to 17 years. * Diagnosed rhinitis with medical history consistent with HDM-induced allergic rhinitis for at least 1 year before visit 1 * Positive Skin Prick Test to House Dust Mites(HDM)and HDM-specific IgE serum value ≥ 0.7 kUnit/L. * Concommittant controlled asthma allowed up to GINA 1 or 2 treatment step * Spirometry with best FEV1 \> 80% of predicted FEV1. Exclusion Criteria: * Patient with a nasal or oral disease that could interfere with the safety assessments * Patient has undergone recent nasal surgery * Patient with asthma receiving therapy consistent with GINA (Global INitiative for Asthama) treatment step 3, 4, or 5. * Patient with partially controlled or uncontrolled asthma * 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. * Female patient pregnant or breast-feeding/lactating. * Female patient of childbearing potential planning a pregnancy during this trial or not using a medically accepted contraceptive method. * Patient treated with beta-blockers, tricyclic antidepressants or monoamine oxidase inhibitors (MAOIs). * Patient who received allergy specific immunotherapy for house dust mites for more than 1 month in the 5 years before screening or who is currently receiving immunotherapy with any allergen. * patient with a history of anaphylaxis * patient having participated in any clinical study within the 12 weeks before visit 1