The purpose of this study is to determine whether the oral administration of grass pollen peptides to treat allergic rhinitis is safe and well tolerated.

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