- Phase 1 will enroll 10 cockroach sensitive adults with asthma who will undergo a nasal allergen challenge with increasing doses of cockroach allergen. Phase 1 will consist of two parts, Phase 1a and Phase 1b. In Phase 1a, participants will undergo a nasal allergen challenge. In Phase 1b, participants will undergo a repeat nasal allergen challenge to assess reproducibility of the NAC with cockroach allergen in a population with asthma. The data from Phase 1a will be used to identify a range of doses that is safe and elicits a threshold of nasal symptoms (TNSS ≥8).