Could a severe asthma drug also ease hayfever symptoms?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: For inclusion in the study, all participants should fulfil the following criteria based on local regulations: 1. Must be able and willing to provide written informed consent. 2. Must be willing and able to comply with the study requirements. 3. People between the ages of 18 and 65. 4. Body weight greater than 45 kg. 5. A person of childbearing potential must be either abstinent or using a medically acceptable method of birth control (see Section 3.5) and produce a negative urine pregnancy test at the screening visit and again at each treatment visit. For inclusion in the study, non-allergic participants should fulfil the following additional criteria based on local regulations: 6. Negative skin prick test to all relevant aeroallergen at screening with a wheal diameter no larger than that produced by the negative control. 7. Specific IgE levels to a relevant allergen are undetectable. 8. Negative screening Nasal Allergen Challenge, defined by a TNSS response of ≤ 3 (on a 12-point scale) and a decrease in PNIF of ≤ 30% after 10 minutes in response to a nasal application of a relevant aeroallergen extract. For inclusion in the study, allergic participants should fulfil the following additional criteria based on local regulations: 9. A minimum 2-year documented history of rhinoconjunctivitis symptoms to a relevant aeroallergen. 10. Positive skin prick test to a relevant aeroallergen at screening (matching the history in IC2) with a wheal diameter at least 5 mm larger than that produced by the negative control. 11. A minimum 2-year documented history of asthma, controlled with either moderate or high dose inhaled corticosteroids with or without another controller medication (long-acting beta-agonists and/or montelukast and/or a long-acting muscarinic antagonist. 12. Positive screening Nasal Allergen Challenge, defined by a TNSS response of ≥ 7 (on a 12-point scale) and a decrease in PNIF of ≥ 50% after 10 minutes in response to a nasal application of a relevant aeroallergen extract. Exclusion Criteria: Participants should not enter the study if any of the following exclusion criteria are fulfilled: 1. Involvement in the planning and/or conduct of the study (applies to both Investigator staff and/or staff at the study site). 2. Is unlikely to cooperate with the requirements of the study including having the ability to communicate with the investigator appropriately. 3. Inability to attend study visits or adhere to the study protocol, in the judgment of the principal investigator. 4. Previous enrolment in the present study. 5. Participation in another clinical study with an investigational product during the last 30 days. 6. Known hypersensitivity to the investigational product. 7. Currently uses or is expected to use any of the prohibited medications or other treatments as listed in Section 7.7. 8. An upper respiratory tract infection within 14 days of the NAC portion of the screening visit or baseline NAC visit. 9. History of immunological disorders or other diseases (including, but not limited to malignancy, cardiovascular, gastrointestinal, hepatic, renal, haematological, neurological, endocrine or pulmonary disease) that in the opinion of the investigator may pose additional risk factors for participation. Participants with basal cell carcinoma or squamous cell carcinoma that has been excised in the past 5 years may still participate in the study. 10. Nasal conditions that, according to the opinion of the investigator, may affect the outcome of the study, i.e. nasal septal perforation, current nasal polyps, other nasal malformations or history of frequent nosebleeds. 11. A known history of positive test results for Hepatitis B, Hepatitis C, HIV or tuberculosis other than what would be anticipated following vaccination. 12. Participant has a known history of current or previous parasitic infection. 13. Participant that is pregnant, lactating or actively trying to become pregnant. 14. Participant with a clinically relevant abnormality on physical examination. 15. Participant is unable to communicate or to understand the requirements of the study, which would impair communication between the participant and the investigator. 16. Significant history of alcohol or drug abuse, in the judgment of the investigator. 17. Serious asthma exacerbation requiring a hospital visit and/ or treatment with oral steroids within 4 weeks prior to screening. 18. FEV1 \< 40 % predicted at screening. 19. Pre-NAC TNSS \> 4 at the screening and baseline NAC visit.