2170 Preliminary Evaluation of the Red Maple Trials Allergen Challenge Theatre for Grass Pollen

Thursday, 15 October 2015
Hall D1 Foyer (Floor 3) (Coex Convention Center)

William Yang, MD , Red Maple Trials Inc., Ottawa, ON, Canada

Suzanne Kelly, PhD , Red Maple Trials Inc., Ottawa, ON, Canada

Rob Perrins, P.Eng. , Red Maple Trials Inc., Ottawa, ON, Canada

Jacob Karsh, MDCM , Red Maple Trials Inc., Ottawa, ON, Canada

Jimmy Yang, MBA , Red Maple Trials Inc., Ottawa, ON, Canada

Rationale: Allergen challenge chambers expose allergen-sensitive subjects to a predetermined concentration of allergen in a closed, controlled environment and provide a mechanism to induce clinical symptoms and measure the effect of medication.

Methods:  The Red Maple Trials (RMT) Allergen Challenge Theatre (ACT) is a 4-zone facility holding up to 100 seats in a series of elevated rows. Grass pollen (Phleum pratense) was injected into the air supply and blown into the facility through ducts located across the top of the front wall.  A technical validation was performed to determine stability and uniformity of pollen concentrations in the room.  Pollen counts were measured by a laser particle counter (LPC) positioned 5 ft above floor level and by impact samplers (IS) set at face level.  IS were installed in 5 sections of a T-shaped quadrant and measurements taken every 30 minutes for 180 minutes.  To evaluate the clinical response to grass pollen exposure, subjects with a history of grass allergy and positive skin prick test underwent two 3-hour challenges to grass pollen. Nasal and ocular symptom scores were recorded at baseline and every 30 min during the challenge. 

Results:  For the technical validation, pollen counts measured by LPC were stable for 3 hours at 4,800 ± 500 g/m3.  LPC pollen counts correlated well with IS counts over a range from 1,500 to 7,500 g/m3 (LPC =0.849IS -269.0, r2=0.85). Mean pollen counts in each of the 5 sections of the quadrant ranged from 2,821 ±303 to 5,726 ±249.  For the clinical validation, 17/32 patients had at least one Total Nasal Symptom Score (TNSS) ≥5 at challenge 1.  In these subjects, mean change from baseline TNSS was 4.35±2.32 for challenge 1 and 4.94±2.41 at challenge 2, p=0.48.  Total ocular symptom scores (TOSS) were 1.29±1.31 and 2.29±2.17, p=0.029, respectively.

Conclusion:  The Red Maple Trials ACT demonstrated the capacity to achieve and maintain a stable grass pollen concentration associated with the ability to induce nasal and ocular symptoms of appropriate intensity upon a three-hour allergen challenge.