The objective of this study is to investigate the safety, tolerability, and pharmacokinetics of MT-2990 in patients with Japanese cedar pollen-induced seasonal allergic rhinitis (JC-SAR). Additional objective of the study is to investigate the efficacy and pharmacodynamics profile of MT-2990 in an environmental exposure chamber (EEC) on Day 8, 29, 57, and 85.

Inclusion Criteria:

• A body weight of 40 to 100 kg for female or 45 to 100 kg for male
• A body mass index of 18 to 30 kg/m2
• Subjects who have current history of JC-SAR in previous 2 consecutive years.
• Presence (CAP-RAST: ≥2) of IgE specific to Japanese cedar pollens and absence (CAP-RAST: ≤1) of IgE specific to other 4 allergens
• Presence of at least 2 symptoms, which are moderate to very severe, in 4 nasal symptoms (runny nose, sneezing, blocked nose, itchy nose) at any time point during allergen exposure in EEC at screening period

Exclusion Criteria:

• Presence of any symptoms of allergic rhinitis within 1 year except scattering season of cedar pollen or cypress pollen
• Subjects who have persistent symptom caused by allergen exposure in EEC at screening period until Day 1 (pre-dose)
• Underwent nasal surgery (include laser surgery) to improve nasal symptoms within 2 years
• Underwent specific immunotherapy or non-specific immunotherapy within 5 years
• Underwent medication of anti-histamine, oral mast cell stabilizer, leukotriene receptor antagonist, prostaglandin D2/thromboxane A2 receptor antagonist, Th2 cytokine inhibitor, corticosteroid (oral form, intra-nasal form, ocular form), or vasoconstrictor within 4 weeks
• Underwent medication of corticosteroid (injection form) or anti-IgE antibody within 6 months
• Subject who is concerned about exacerbation of the physical condition due to allergen exposure in EEC