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Dose-range finding of natural birch pollen exposure in patients with seasonal allergic rhinitis in the Fraunhofer Environmental Challenge Chamber

: Lüer, Katrin; Windt, Horst; Schwarz, Katharina; Badorrek, Philipp; Sebastian, Ramona; Haefner, Dietrich; Koch, Wolfgang; Krug, Norbert; Hohlfeld, Jens Michael

Allergy. European journal of allergy and clinical immunology 69 (2014), Supplement 99, pp.73, Abstr. 163
ISSN: 0105-4538
ISSN: 1398-9995
European Acadamy of Allergy and Clinical Immunology (EAACI Congress) <33, 2014, Copenhagen>
Fraunhofer ITEM ()

Introduction: Exposure to natural grass pollen in the Fraunhofer Environmental Challenge Chamber (ECC) has been validated and extensively applied for clinical development of investigational new drugs. Efficacy testing of immunotherapy using ECC needs allergen-specific exposures. The aim of this study was to test the safety and efficacy with dose-range finding and reproducibility of birch pollen challenge in subjects with seasonal allergic rhinitis in the Fraunhofer ECC.
Methods: In a monocenter, single-blind, placebo-controlled, six period dose escalation pilot study 18 subjects with seasonal allergic rhinitis and sensitisation to birch pollen were exposed to clean air (placebo) or birch pollen (Allergon AB, Sweden) at either 1000, 2000, 4000, and 8000 grains/m3 for 4 h in the Fraunhofer ECC 7 days apart. The dose of 4000 grains /m3 was repeated to investigate reproducibility. Efficacy (total nasal symptom score (TNSS), nasal flow rate, nasal secretion) and safety (adverse events, lung function) were assessed prior to and during the exposures.
Results: While symptoms were absent prechallenge (TNSS = 0), exposure to birch pollen increased TNSS (mean of last 2 h ±SD) to 3.5± 0.2, 4.0± 0.2, 4.3± 0.2, and 4.3 ± 0.2 at 1000, 2000, 4000, and 8000 grains/m3, respectively, while air alone had little effect on TNSS (1.4 ± 0.2). Repeated exposure to 4000 grains/m³ induced a mean TNSS of 4.3 \'03 0.3 which was not statistically different compared to the same previous dose. Objective measures of nasal flow and nasal secretions were in line with clinical symptoms. Exposure to birch pollen was safe with no relevant change in FEV1.
Conclusion: Exposure to natural birch pollen at increasing concentrations in patients with allergic rhinitis in the Fraunhofer ECC was safe and induced symptoms of allergic rhinitis with a narrow doseresponse and evidence of saturation. A dose of 4000 grains/m3 was effective, reproducible and can therefore be used in future clinical trials.