Standardising Nasal Allergen Challenge in Adult With Hay Fever

Allergic Rhinitis Clinical Trial

Official title: Nasal Allergen Challenge: Standardisation as a Surrogate for Hay Fever

Status Completed

Clinical Trial Summary

Hay fever affects 1 in 4 of the UK population and has significant effects on the quality of life of sufferers. Allergy to grass pollen is the most common cause. A detailed understanding of the mechanisms involved during allergic reactions to pollens in hay fever sufferers may provide improvements in diagnosis, drug treatment and assessment of their response to treatment. Controlled exposures to allergens such as grass pollen can provide important information on the mechanisms of allergic inflammation and may be used to assess the success of anti-allergy treatments. Nasal allergen challenge (NAC) is a useful tool in the investigation of allergic rhinitis, including grass pollen-induced seasonal allergic rhinitis (hay fever). NAC is performed by installation of a very small amount of grass pollen extract into the nose in order to reproduce mild and short-lived symptoms such as nasal itch, sneezing, runny nose and nasal congestion that you experience in a more severe form during natural exposure to grass pollen during the summer. Nasal allergen challenge has allowed us to explore the mechanism of hay fever and to provide a rapid and reliable method for investigating new potential treatments for hay fever. Nasal allergen Challenge is a very well-standardised and safe procedure that has been performed within the department of Allergy and Clinical Immunology at Imperial College and Royal Brompton Hospital for many years. Unfortunately the grass pollen extract ('Aquagen') that we have routinely used for nasal challenge has been discontinued and is therefore no longer available. The present study involves testing an alternative source of the grass pollen extract in the form of 'Grazax' which is a freeze-dried tablet that is highly standardised and should enable us to give an identical amount of grass pollen extract for the purpose of nasal challenge. We plan a 'head-to-head' comparison of the two extracts in nasal challenge in order to confirm that the two sources of allergen are equivalent thereby enabling us to use Grazax as the source of grass pollen extract for our nasal challenge studies in the future.

Clinical Trial Description

Nasal allergen challenge (NAC) is a useful tool in the investigation of allergic rhinitis, including grass pollen-induced seasonal allergic rhinitis (hay fever). We have experience in using NAC to investigate the clinical and immunological effects of allergen exposure and in using NAC as a surrogate outcome to assess the efficacy of treatments for allergic rhinitis. The procedure is safe and well tolerated. In order for NAC to be a valid tool, it is essential that the allergen extracts used are standardised in terms of concentration and stability in solution. We have previously used an extract of Timothy Grass (Phleum pratense) pollen, Aquagen (ALK-Abello, Denmark). Aquagen is supplied as a dry powder, to be reconstituted prior to use by dissolving in an albumin-based diluent. Unfortunately, Aquagen production has been discontinued, but the identical allergen is now available as Timothy Grass lyophilisate tablet, Grazax (ALK-Abello), an approved and licensed product for treatment of severe seasonal allergic rhinitis. Grazax consists of purified, freeze-dried Timothy Grass pollen extract, plus only three excipients, gelatin (from fish), mannitol and sodium hydroxide. Preliminary investigations have shown that Grazax tablets can be dissolved in saline to produce identical concentrations of allergen to Aquagen, with the same stability profile in vitro. We anticipate therefore, that the clinical effect when used for nasal allergen challenges would be equivalent to the use of Aquagen for a given allergen concentration. In this study we intend to confirm that nasal symptoms produced during the NAC with either Aquagen or Grazax will be equivalent. We will recruit volunteers with grass pollen-induced hay fever to undergo NAC with each allergen source, sequentially. In an open, randomised-order, cross-over study. The primary outcome will be patient-reported nasal symptoms (according to a standardised scoring system) in the 60 minutes after each nasal challenge. ;

Related Conditions & MeSH terms

• Allergic Rhinitis
• Rhinitis
• Rhinitis, Allergic

• NCT number: NCT04078009
• Study type: Interventional
• Source: Imperial College London
• Status: Completed
• Phase: N/A
• Start date: September 26, 2019
• Completion date: August 28, 2020