A Dose-response Evaluation of the SQ Tree SLIT-tablet Using an Environmental Exposure Chamber

Inclusion Criteria: * Written informed consent obtained before any trial related procedures are performed * Male or female aged 18 to 65 years * Female subjects of child-bearing potential must have a negative urine pregnancy test and be willing to practise contraceptive methods * History of moderate-to-severe rhinoconjunctivitis induced by pollens from the birch group with or without asthma despite having received treatment with symptom relieving medication during the previous 2 tree pollen seasons * Positive SPT response (wheal diameter ≥ 3 mm) to Betula verrucosa * Positive specific IgE against Bet v1 (≥ IgE Class 2; ≥0.70 kU/L) * Willing and able to comply with the trial protocol * Minimum level of rhinoconjunctivitis symptoms, defined as a TSS of at least 7 (of 18), at one timepoint during birch baseline EEC session. Exclusion Criteria: * Symptoms induced by interfering allergens that are expected to be present during the periods where the subject attends the EEC sessions * Rhinoconjunctivitis caused by animal hair and dander to which the subject is regularly exposed. * Allergic symptoms induced by perennial allergens such as house dust mites, and moulds * A clinical history of uncontrolled asthma within 3 months prior to screening * Reduced lung function FEV1 (\< 70% of predicted value after adequate pharmacological treatment) * Asthma requiring treatment with inhaled corticosteroid within the past 3 months prior to screening * Previous treatment with any allergy immunotherapy product with tree pollen allergens or a cross-reacting allergen within the past 5 years * Ongoing treatment with any allergy immunotherapy product * Immunosuppressive treatment within 3 months prior to the screening visit * Treatment with tricyclic antidepressants, catecholamine-O-methyltransferase inhibitors, mono amine oxidase inhibitors and beta-blockers * Treatment with antidepressant medication with antihistaminic effect * Treatment with antipsychotic medications with antihistaminic effect * Treatment with anti-IgE drugs within 130 days/5 half-lives of the drug (which ever longest) * Treatment with an investigational drug within 30 days/5 half-lives of the drug (which ever longest) prior to screening * Severe oral inflammation or oral wounds at randomisation * Symptoms of or treatment for upper respiratory tract infection, acute sinusitis, acute otitis media or other relevant infections that have not resolved 1-week prior to the baseline birch and oak Environmental Exposure Chamber sessions and at the randomisation visit * Clinically relevant nasal polyps * A history of paranasal sinus surgery * A history of surgery of nasal turbinates * A history of anaphylaxis with cardiorespiratory symptoms * A history of recurrent (defined as two or more episodes) generalised urticaria during the last 2 years * A history of drug-induced (incl. Allergy Immunotherapy) facial angioedema or a family (parents and siblings) history of hereditary angioedema * Any clinically relevant chronic disease (≥3 months duration) that in the opinion of the investigator would interfere with the trial assessments or the safety of the subject * An uncontrolled systemic disease affecting the immune system (e.g. insulin-dependent diabetes, autoimmune disease, immune complex disease, or immune deficiency disease whether acquired or not) * A history of allergy, hypersensitivity or intolerance to the investigational medicinal product (except Betula verrucosa) or any of the symptomatic medications provided in this trial * Being immediate family of the investigator or trial staff, defined as the investigator's/staff's spouse, parent, child, grandparent or grandchild.