An Exploratory Study of PQ Grass 27600 SU

PQGrass309 is a randomised, double-blind, placebo-controlled exploratory study to explore the efficacy and safety of PQ Grass 27600 SU in subjects with seasonal allergic rhinitis and/or rhinoconjunctivitis (SAR) induced by grass pollen exposure. The study is expected to be conducted in the United States (US) and the European Union (EU). The aim of this exploratory field study is to explore amongst others the following: * The efficacy and safety (up to 6 months following treatment) of a cumulative dose of 27600 standardised units (SU) of PQ Grass in the treatment of grass pollen allergy. * The expected average treatment effect on combined symptom and medication score.