Safety of ToleroMune Ragweed to Treat Ragweed Allergy in Ragweed Allergic Subjects With Rhinoconjunctivitis

This study is designed as a randomised, double-blind, placebo-controlled study to evaluate the safety and tolerability of escalating multiple doses of ToleroMune Ragweed in subjects with a documented history of allergic rhinoconjunctivitis on exposure to ragweed pollen. The efficacy of ToleroMune Ragweed will also be explored in these subjects using the LPSR, EPSR, CPT and levels of ragweed specific IgE. A single centre will be initiated first, with a second centre included as a backup, if needed, to enable recruitment numbers to be met.

The study will consist of 3 study periods. In Period 1, Screening will be performed up to a maximum of 8 weeks before randomisation and may consist of one or two visits to the clinic, at the Investigator's discretion. Baseline Challenge will consist of a single visit 1 to 4 weeks before randomisation.

Period 2 (Treatment Period) will consist of 4 visits (Visits 3A-3D) two weeks apart (14±2 days). Subjects who comply with the inclusion/exclusion criteria will be assigned to one of 5 dose groups. The first dose group will receive 4 administrations of ToleroMune Ragweed. Successive dose groups will increasing doses given as 4 administrations of ToleroMune Ragweed, provided the first administration of the previous dose was safe and well tolerated.

In Period 3, Post-treatment Challenge will take place 19-25 weeks after the first administration in the Treatment Period and will be timed to be outside the Ragweed season. However in the event that the Ragweed season lasts beyond 26th October 2009, the PTC will take place 22-28 weeks after the first administration in the Treatment Period. Assessments performed will be identical to those at the Baseline Challenge. Follow-up will be conducted 3-10 days after PTC.