Safety and Tolerance Study of Grass Pollen-derived Peptides to Treat Allergic Rhinitis

Inclusion Criteria: * Age between 18 and 50 years * The subjects are in good physical and mental health according to his/her medical history, vital signs, and clinical status * Male or non-pregnant, non-lactating females * A history of seasonal allergic rhinoconjunctivitis (SAR) during the grass pollen season during at least the last two years * A positive skin prick test to grass-pollen mixture * Specific IgE against grass pollen (RAST class 2 or IgE \> 0.7 kU/l) * Asymptomatic to perennial inhalant allergens Exclusion Criteria: * Subjects with current or past immunotherapy for SAR * Subjects requiring controller medication against asthma (bronchodilator nebulised drugs or local or systemic corticosteroids) * Documented evidence of acute or significant chronic sinusitis (as determined by individual investigator) * Subjects with a history of food allergy and consecutive anaphylaxis * Subjects with a history of hepatic or renal disease * Subject with malignant disease, autoimmune disease * Female subjects who are pregnant, lactating, or of child-bearing potential and not protected from pregnancy by a sufficiently reliable method (OCs, IUD). * Females unable to bear children must have documentation of such (i.e. tubal ligation, hysterectomy, or post menopausal \[defined as a minimum of one year since the last menstrual period\]) * Any chronic disease, which may impair the subject's ability to participate in the trial (i.e. severe congestive heart failure, active gastric or duodenal ulcer, uncontrolled diabetes mellitus, etc…) * Subjects with clinically relevant abnormal QTc intervals of the ECG : QTc \> 450 ms for man and \> 470 ms for women * Subjects requiring beta-blockers medication * Chronic use of concomitant medications that would affect assessment of the effectiveness of the study medication (e.g. tricyclic antidepressants) * Subject with febrile illness (\> 37.5°C, oral) * A known positive serology for HIV-1/2, HBs antigen or anti-HCV antibodies * The subject is immunocompromised by medication or illness, has received a vaccine, corticoids or immunosuppressive medications within 1 month before study entry * Receipt of blood or a blood derivative in the past 6 months preceding study entry * Regular consumption of corticoids (oral, topic or nasal) or of anti-histaminic drugs within 4 weeks preceding the study, any consumption of corticoids (oral, topic or nasal) or of anti-histaminic drugs within 1 week preceding the study * Use of long-acting antihistamines * Any condition which could be incompatible with protocol understanding and compliance * Subjects who have forfeited their freedom by administrative or legal award or who are under guardianship, * Participation in another clinical trial and/or treatment with an experimental drug within 1 month of study start * A history of hypersensitivity to the excipients