Key Inclusion Criteria:

• Male or female patients 12 years of age and older, as of the Screening Visit (SV).
• General good health, and free of any concomitant conditions or treatment that could interfere with study conduct, influence the interpretation of study observations/results, or put the patient at increased risk during the study.
• A history of SAR to relevant seasonal allergen (tree/grass pollen) for a minimum of two years immediately preceding the study Screening Visit (SV).

The SAR must have been of sufficient severity to have required treatment (either continuous or intermittent) in the past and in the investigator's judgment is expected to be exposed to the allergen and require treatment throughout the entire study period.

• A demonstrated sensitivity to relevant tree/grass pollen known to produce SAR through a standard skin prick test. A positive test is defined as a wheal diameter at least 3 mm larger than the control wheal for the skin prick test. Documentation of a positive result within 12 months prior to Screening Visit (SV) is acceptable.
• Other criteria apply

Key Exclusion Criteria:

• Participation in any investigational drug study within the 30 days preceding the Screening Visit (SV) or planned participation in another investigational drug study at any time during this study.
• History of physical findings of nasal pathology, including nasal polyps or other clinically significant respiratory tract malformations, recent nasal biopsy, nasal trauma or surgery, atrophic rhinitis, or rhinitis medicamentosa (all within the last 60 days prior to the SV).
• History of a respiratory infection or disorder [including, but not limited to bronchitis, pneumonia, chronic sinusitis, influenza, severe acute respiratory syndrome (SARS)] within the 14 days preceding the Screening Visit (SV), or development of a respiratory infection during the Run-in Period.
• Use of any prohibited concomitant medications within the prescribed (per protocol) time since the last dosing period prior to the Screening Visit (SV) and/or plans for use during the entire treatment duration.
• Other criteria apply